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General Discussion => Advanced Concepts => Topic started by: Chris Bergin on 02/18/2015 11:15 am

Title: The Reaction Engines Skylon Master Thread (5)
Post by: Chris Bergin on 02/18/2015 11:15 am
Fifth thread for Reaction Engines/Skylon.

Previous: The Reaction Engines Skylon Master Thread (4)
http://forum.nasaspaceflight.com/index.php?topic=34964.0

This has to be on topic and civil. This is for sensible debate and updates. Anything trivial or stupid will be deleted without notice.
Title: Yield (on bonds, investments, and so on)
Post by: jrc14 on 02/18/2015 02:47 pm
Just to clarify a point on 'yield' that seems to be causing misunderstanding, and responding to recent posts (in thread #4) by t43562, francesco nicoli and others ...

Why I think I know the answer: I have been working in investment banks building quant models (including models of bonds and other investments) for the past 25 years
Why it's important: thanks, in part, to imprecise wording in the investopedia article on 'Yield', forum readers might misunderstand how 'yield' is calculated - and so they'll get a wildly misleading view of how the Skylon business case works (or does not work)
What the answer is: when people quote 'bond yield' or 'return on investment' or 'interest' as a percentage figure, that is always an annual figure (its units being "quantity per cent per year").
The answer in tedious detail:
Suppose that somebody issues, and that I buy, a ten year bond paying a yield of 8%, and that I buy $100 of this bond.  The financial outcome is:
I pay today $100
I receive 1 year from now $8 (interest, also known as coupon)
I receive 2 years from now $8 (interest, also known as coupon)
...
I receive 10 years from now $108 (being repayment of my initial $100 plus $8, being the final interest payment)

So overall, I have paid out $100 and I have received $180.  Deciding whether this was a fair deal (for me or for the bond issuer) is a complex question, and for those wanting an answer the Wikipedia article on Discounting  (http://en.wikipedia.org/wiki/Discounting) is as good a place to start as any.
Bank account interest, loans, mortgages and so forth all follow this general pattern.  The interest rate is an annual amount, describing how much interest is paid each year.

[Note: to the pedants out there: yes, I am aware of semi-annual interest, compounding, daycount convention, the definition of IRR, the difference between nominal/coupon yield, current/OTR yield and redemption yield, the roles of exchanges, depositories and clearing houses, ... . I have simplified the explanation, for the sake of exposition.  If you know enough to challenge me on any of these details, you also know enough to agree with my central point, which is that yield is an annual amount]

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Impaler on 02/18/2015 05:28 pm
jrc14:  Thank you for for that well written post.  I hope this settle the matter for anyone still in doubt and we may now discuss how Skylon business case closes/dose-not-close using correct financial principles.

jrc14, can you give us some rough estimates of what a potential Skylon operators cost of capitol might be and thus generate some estimates of what kind of gross profit is needed over a range of time-frames to breakeven.

Lets assume 1 Billion is the initial outlay for the Skylon, and time periods are 2 year, 5, years, 10 years, 20 years.  How much do they need to make over and above operating costs per year and over the period in question to justify the investment?
Title: Re: Yield (on bonds, investments, and so on)
Post by: t43562 on 02/18/2015 05:42 pm
Just to clarify a point on 'yield' that seems to be causing misunderstanding, and responding to recent posts (in thread #4) by t43562, francesco nicoli and others ...
What the answer is: when people quote 'bond yield' or 'return on investment' or 'interest' as a percentage figure, that is always an annual figure (its units being "quantity per cent per year").

Thanks for the explanation.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 02/18/2015 06:06 pm
To start off the new thread, here's a summary of my own reasons for being skeptical about Skylon.  Some of these views are probably shared by other skeptics.  Feel free to reply with opposing views; hopefully, this will help clarify exactly where opinions differ and help undecided readers of these forums see both sides and make up their own minds.

First off, I don't think there's a known flaw in Skylon that definitely makes it impossible.  It's not like a perpetual motion machine that violates known laws of physics.  My issue with Skylon is that there are too many unknowns and the proponents of Skylon assume those unknowns will work out, while history shows this is seldom the case.  There are enough unknowns and enough projections that seem very optimistic to me that the odds of Skylon actually achieving its goals seem remote to me.

The people working on Skylon have been working on the idea for decades.  They are certainly dedicated and well-meaning, and they have some competence.  But they have been working on theory and small components.  They don't have experience in system integration.  They haven't built real flight hardware.  They haven't seen a system from concept through to all the inevitable compromises necessary to make a practical system.

The team at REL has consistently proposed building a large-scale single-stage-to-orbit system.  That shows poor judgement, in my opinion.  SpaceX started with Falcon 1.  Then then moved to a full-expendable Falcon 9.  Now they are working on perfecting reuse of only the first stage.  Along the way, they have learned many lessons and constantly changed their plans, all while retaining their goal of greatly reducing the cost of launch.  I believe that kind of incremental, flexible approach is very effective.  It is the opposite of the REL approach.  With REL going directly for a huge, single-stage-to-orbit system, there is little room to learn operational lessons and change plans.  And Skylon is so much different from existing systems it is very likely to need far more flexibility for lessons learned than Falcon.

There have been many programs with similar or lesser optimistic goals that have failed.  The U.S. National Aerospace Plane had far more resources available and a similar level of technological challenge, and it failed.  Note that I'm not saying the details of the technological challenge are similar -- they are not.  But the programs are similar in having a goal that required many unknowns to be overcome and having people with some competence in specific areas convinced they could overcome them.

The X-33/VentureStar is another launch program that had optimistic goals and failed.  I think that X-33/VentureStar looked far more realistic at its outset, with less of a techonological leap required, than Skylon today.  And yet it failed because of the engineering details in turning the theory into reality.

I also find the projected business model of Skylon implausible.  It posits 30 units of Skylon will be bought for a billion dollars each.  That would give a launch capability far, far beyond the current market, at a price not enough lower to justify the enormous market expansion.  One commonly-used cost figure is $5 million per flight based on 200 flights per vehicle and 30 vehicles.  If the market were really there for such a launch rate, SpaceX could develop a fully-reusable upper stage for Falcon 9 and cover it at an even lower cost.

Another part of the business case is that governments will by Skylon units for prestige.  I think that's unrealistic because national space programs get prestige from developing indigenous capabilities far more than by buying from another country.

So, there you have it.  If you disagree, post what you disagree with and why.  If you're a reader and undecided, read this and the responses and make up your own mind.

One final note: I hope I'm wrong and that Skylon beats the odds and succeeds.  But hope shouldn't mean we aren't realistic about how unlikely something is.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 02/18/2015 07:13 pm
The people working on Skylon have been working on the idea for decades.  They are certainly dedicated and well-meaning, and they have some competence.  But they have been working on theory and small components.  They don't have experience in system integration.  They haven't built real flight hardware.  They haven't seen a system from concept through to all the inevitable compromises necessary to make a practical system.

I don't have a biography to hand of each one of them but I suggest that it's a sweeping statement to say that they have no experience in system integration.  At the very least some of them are veterans of Blue Streak and others of the aerospace industry.

The team at REL has consistently proposed building a large-scale single-stage-to-orbit system.  That shows poor judgement, in my opinion.  SpaceX started with Falcon 1.  Then then moved to a full-expendable Falcon 9.  Now they are working on perfecting reuse of only the first stage.  Along the way, they have learned many lessons and constantly changed their plans, all while retaining their goal of greatly reducing the cost of launch.  I believe that kind of incremental, flexible approach is very effective.  It is the opposite of the REL approach.  With REL going directly for a huge, single-stage-to-orbit system, there is little room to learn operational lessons and change plans.  And Skylon is so much different from existing systems it is very likely to need far more flexibility for lessons learned than Falcon.

If my memory serves me their contention is that a smaller system does not offer the economic benefits. In other words the nature of the problem dictates the way they have to go - they can't scale up over time.  Assuming this is true, what do you expect them to do?

I think it's also fair to say that if they can build a demonstrator engine they'll be able to remake their decisions having learned from it. I don't see them claiming that their plan is set in stone. If you consider HOTOL, they have already learned and changed quite a lot.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Lars-J on 02/18/2015 08:40 pm
The people working on Skylon have been working on the idea for decades.  They are certainly dedicated and well-meaning, and they have some competence.  But they have been working on theory and small components.  They don't have experience in system integration.  They haven't built real flight hardware.  They haven't seen a system from concept through to all the inevitable compromises necessary to make a practical system.

I don't have a biography to hand of each one of them but I suggest that it's a sweeping statement to say that they have no experience in system integration.  At the very least some of them are veterans of Blue Streak and others of the aerospace industry.

But that goes for almost any aerospace start-up. Among its employees you would expect to see some veterans from other aerospace firms - but that does not mean that the "organizational experience" as a whole translates to this new organization. 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 02/18/2015 09:25 pm
The people working on Skylon have been working on the idea for decades.  They are certainly dedicated and well-meaning, and they have some competence.  But they have been working on theory and small components.  They don't have experience in system integration.  They haven't built real flight hardware.  They haven't seen a system from concept through to all the inevitable compromises necessary to make a practical system.

I don't have a biography to hand of each one of them but I suggest that it's a sweeping statement to say that they have no experience in system integration.  At the very least some of them are veterans of Blue Streak and others of the aerospace industry.

But that goes for almost any aerospace start-up. Among its employees you would expect to see some veterans from other aerospace firms - but that does not mean that the "organizational experience" as a whole translates to this new organization.

That is a different argument - if we are respecting the English language and the use of absolutes.

They are an engine company not an airframe company.   Let the airframe company use its great institutional experience for its part of the work.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 02/18/2015 09:28 pm
The people working on Skylon have been working on the idea for decades.  They are certainly dedicated and well-meaning, and they have some competence.  But they have been working on theory and small components.  They don't have experience in system integration.  They haven't built real flight hardware.  They haven't seen a system from concept through to all the inevitable compromises necessary to make a practical system.

I don't have a biography to hand of each one of them but I suggest that it's a sweeping statement to say that they have no experience in system integration.  At the very least some of them are veterans of Blue Streak and others of the aerospace industry.

But that goes for almost any aerospace start-up. Among its employees you would expect to see some veterans from other aerospace firms - but that does not mean that the "organizational experience" as a whole translates to this new organization.

That is a different argument - if we are respecting the English language and the use of absolutes.

They are an engine company not an airframe company.   Let the airframe company use its great institutional experience for its part of the work.

That's fine, but this engine company is making projections about the performance and economic viability of the complete system, including engines and airframe.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 02/18/2015 09:49 pm
The people working on Skylon have been working on the idea for decades.  They are certainly dedicated and well-meaning, and they have some competence.  But they have been working on theory and small components.  They don't have experience in system integration.  They haven't built real flight hardware.  They haven't seen a system from concept through to all the inevitable compromises necessary to make a practical system.

I don't have a biography to hand of each one of them but I suggest that it's a sweeping statement to say that they have no experience in system integration.  At the very least some of them are veterans of Blue Streak and others of the aerospace industry.

But that goes for almost any aerospace start-up. Among its employees you would expect to see some veterans from other aerospace firms - but that does not mean that the "organizational experience" as a whole translates to this new organization.

That is a different argument - if we are respecting the English language and the use of absolutes.

They are an engine company not an airframe company.   Let the airframe company use its great institutional experience for its part of the work.

That's fine, but this engine company is making projections about the performance and economic viability of the complete system, including engines and airframe.

Don't they have to? Is it not necessary at all times to make such projections and keep updating them as new information is learned? Would anyone even bother to invest if the projections of today were bad? It doesn't mean their projections are 'plucked out of the air' or based on nothing.  So they will build their test engine and perhaps other things on the way and then their projections will have much more authority whatever they turn out to be but for now we have what we have and can only discuss that.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 02/18/2015 11:30 pm
That's fine, but this engine company is making projections about the performance and economic viability of the complete system, including engines and airframe.

Don't they have to? Is it not necessary at all times to make such projections and keep updating them as new information is learned?

There'd be no shame in their saying "we don't know yet".

Would anyone even bother to invest if the projections of today were bad?

Lots of people make lots of bad investments.  The mere fact that someone has invested in not sufficient to overrule our judgement if we have reason to doubt a projection.

The projections of the early Space Shuttle studies were way off.  The projections of the X-33/VentureStar project were way off.  And in both of those cases you had organizations with much more relevant experience.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 02/18/2015 11:50 pm
To start off the new thread, here's a summary of my own reasons for being skeptical about Skylon.  Some of these views are probably shared by other skeptics.  Feel free to reply with opposing views; hopefully, this will help clarify exactly where opinions differ and help undecided readers of these forums see both sides and make up their own minds.

First off, I don't think there's a known flaw in Skylon that definitely makes it impossible.  It's not like a perpetual motion machine that violates known laws of physics.  My issue with Skylon is that there are too many unknowns and the proponents of Skylon assume those unknowns will work out, while history shows this is seldom the case.  There are enough unknowns and enough projections that seem very optimistic to me that the odds of Skylon actually achieving its goals seem remote to me.

The people working on Skylon have been working on the idea for decades.  They are certainly dedicated and well-meaning, and they have some competence.  But they have been working on theory and small components.  They don't have experience in system integration.  They haven't built real flight hardware.  They haven't seen a system from concept through to all the inevitable compromises necessary to make a practical system.

I don't think you are fully aware of the background the REL team. Mark Hempsell for example worked on the DCX.
http://forum.nasaspaceflight.com/index.php?topic=19127.msg493088#msg493088


The team at REL has consistently proposed building a large-scale single-stage-to-orbit system.  That shows poor judgement, in my opinion.  SpaceX started with Falcon 1.  Then then moved to a full-expendable Falcon 9.  Now they are working on perfecting reuse of only the first stage.  Along the way, they have learned many lessons and constantly changed their plans, all while retaining their goal of greatly reducing the cost of launch.  I believe that kind of incremental, flexible approach is very effective.  It is the opposite of the REL approach.  With REL going directly for a huge, single-stage-to-orbit system, there is little room to learn operational lessons and change plans.  And Skylon is so much different from existing systems it is very likely to need far more flexibility for lessons learned than Falcon.

SABRE is a SSTO engine, I'm not sure what intermediate stage there can be for engine explicitly designed to take a single stage into orbit. I can't imagine designs cost get significantly smaller by making a smaller version.


There have been many programs with similar or lesser optimistic goals that have failed.  The U.S. National Aerospace Plane had far more resources available and a similar level of technological challenge, and it failed.  Note that I'm not saying the details of the technological challenge are similar -- they are not.  But the programs are similar in having a goal that required many unknowns to be overcome and having people with some competence in specific areas convinced they could overcome them.
The technical challenge of airbreathing to Mach 18 is clearly of a vastly higher level than airbreathing to Mach 5.5 and the number of unknowns in geting to Mach 18 in 1984 far greater than achieving Mach 5 thirty years later.


The X-33/VentureStar is another launch program that had optimistic goals and failed.  I think that X-33/VentureStar looked far more realistic at its outset, with less of a techonological leap required, than Skylon today.  And yet it failed because of the engineering details in turning the theory into reality.

X-33 didn't fail, it was cancelled due to a change in administration, just as many Clinton era space programs were cancelled by the Bush administration. What many people forget is that the X-33 was just a rocket powered x-plane like the X-15, like the X-15 it had a ton of not flown before technology some of which had teething problems, and like the X-55 if it had flown it would have provided invaluable hypersonic flight data.


I also find the projected business model of Skylon implausible.  It posits 30 units of Skylon will be bought for a billion dollars each.  That would give a launch capability far, far beyond the current market, at a price not enough lower to justify the enormous market expansion.  One commonly-used cost figure is $5 million per flight based on 200 flights per vehicle and 30 vehicles.  If the market were really there for such a launch rate, SpaceX could develop a fully-reusable upper stage for Falcon 9 and cover it at an even lower cost.
Your comparing apples to oranges, the current launch capability is already far, far, larger than the current launch market and yet it is sustained by it. Further 30 Skylons are not just going to come into existence upon the commencement of commercial availability, they have to be built. At a rate of 2 a year there wouldn't be 30 Skylon's arround until 2040, 35 years from the current market. Finally the question that needs to be asked isn't how many launches could be made each year but how few could be made while still turning a profit at a competitive price because if a profit can be made nothing else matters.What seems to be the case is that at an incremental launch cost of $5 million a very high launch rate can spread fixed costs so widely that the market launch price can be not much more than that or at a much lower launch rate the market price can be competitive with current launchers.


Another part of the business case is that governments will by Skylon units for prestige.  I think that's unrealistic because national space programs get prestige from developing indigenous capabilities far more than by buying from another country.

The business case for governments is massively more responsive space access and, for currently non-space-faring countries, a greatly increased asssured access to space and sovereign space capability as well the economic development that comes with having such assets akin to governments having national flag airlines, building massive hub airports and ports etc.
 
So, there you have it.  If you disagree, post what you disagree with and why.  If you're a reader and undecided, read this and the responses and make up your own mind.

One final note: I hope I'm wrong and that Skylon beats the odds and succeeds.  But hope shouldn't mean we aren't realistic about how unlikely something is.


Personally I think the greatest threat to Skylon development will be a failure of an airframer to commit to it. I think REL may find that despite developing an engine that works well and engenders a lot of interest in the end there may be a general reticence to throw in with another companies grand scheme and disrupt their own planning among the likely consortium partners. I could see REL being bought by RR as a part of an attempt at forming a successful consortium only to end being used to get some lucrative US hypersonics research money.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 02/19/2015 12:07 am
To start off the new thread, here's a summary of my own reasons for being skeptical about Skylon.  Some of these views are probably shared by other skeptics.  Feel free to reply with opposing views; hopefully, this will help clarify exactly where opinions differ and help undecided readers of these forums see both sides and make up their own minds.

First off, I don't think there's a known flaw in Skylon that definitely makes it impossible.  It's not like a perpetual motion machine that violates known laws of physics.  My issue with Skylon is that there are too many unknowns and the proponents of Skylon assume those unknowns will work out, while history shows this is seldom the case.  There are enough unknowns and enough projections that seem very optimistic to me that the odds of Skylon actually achieving its goals seem remote to me.

The people working on Skylon have been working on the idea for decades.  They are certainly dedicated and well-meaning, and they have some competence.  But they have been working on theory and small components.  They don't have experience in system integration.  They haven't built real flight hardware.  They haven't seen a system from concept through to all the inevitable compromises necessary to make a practical system.

I don't think you are fully aware of the background the REL team. Mark Hempsell for example worked on the DCX.
http://forum.nasaspaceflight.com/index.php?topic=19127.msg493088#msg493088

Actually, that demonstrates my point quite well.  DC-X never progressed to an operational vehicle.  It was never more than a sub-scale technology demonstrator.  Working on DC-X wouldn't give any experience with the very difficult transition from technology demonstration to a system that is economically successful as an operational system.

And "worked on" isn't the same as being in charge.


The team at REL has consistently proposed building a large-scale single-stage-to-orbit system.  That shows poor judgement, in my opinion.  SpaceX started with Falcon 1.  Then then moved to a full-expendable Falcon 9.  Now they are working on perfecting reuse of only the first stage.  Along the way, they have learned many lessons and constantly changed their plans, all while retaining their goal of greatly reducing the cost of launch.  I believe that kind of incremental, flexible approach is very effective.  It is the opposite of the REL approach.  With REL going directly for a huge, single-stage-to-orbit system, there is little room to learn operational lessons and change plans.  And Skylon is so much different from existing systems it is very likely to need far more flexibility for lessons learned than Falcon.

SABRE is a SSTO engine, I'm not sure what intermediate stage there can be for engine explicitly designed to take a single stage into orbit. I can't imagine designs cost get significantly smaller by making a smaller version.

REL is the one who chose to design it for an SSTO vehicle.  They chose to optimize it for that role rather than as part of a reusable first stage of a two-stage launch system, which would be the more conservative choice and give them more margin and require much less in the way of pushing the edge of what technology can do.

And everything gets cheaper when things are smaller.


There have been many programs with similar or lesser optimistic goals that have failed.  The U.S. National Aerospace Plane had far more resources available and a similar level of technological challenge, and it failed.  Note that I'm not saying the details of the technological challenge are similar -- they are not.  But the programs are similar in having a goal that required many unknowns to be overcome and having people with some competence in specific areas convinced they could overcome them.
The technical challenge of airbreathing to Mach 18 is clearly of a vastly higher level than airbreathing to Mach 5.5 and the number of unknowns in geting to Mach 18 in 1984 far greater than achieving Mach 5 thirty years later.

Getting to Mach 5.5 isn't the challenge.  They still have to get to Mach 25 to make orbit.  True, in some ways it's easier if they're only air breathing to Mach 5.5.  But in other ways it's harder.  They have to carry much more oxidizer, and their engine has to work well in both air-breathing and rocket mode.  Going from Mach 5.5 to Mach 25 in rocket mode (with some of that rocket mode in the dense part of the atmosphere at Mach 5.5) means they need a very good mass fraction.

Like I said, they don't have exactly the same challenges NASP had, but they have very great challenges, and I think they're at a comparable level of difficulty.  Apparently, others think they are too, which is why others are continuing SCRAMJet research and development.

The X-33/VentureStar is another launch program that had optimistic goals and failed.  I think that X-33/VentureStar looked far more realistic at its outset, with less of a techonological leap required, than Skylon today.  And yet it failed because of the engineering details in turning the theory into reality.

X-33 didn't fail, it was cancelled due to a change in administration, just as many Clinton era space programs were cancelled by the Bush administration. What many people forget is that the X-33 was just a rocket powered x-plane like the X-15, like the X-15 it had a ton of not flown before technology some of which had teething problems, and like the X-55 if it had flown it would have provided invaluable hypersonic flight data.

Getting into the details of X-33 is off topic, but lets just say that opinions differ about X-33 -- many people believe it was cancelled because the progress up to that point indicated it was not able to meet its projections and wouldn't have been viable.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SleeperService on 02/19/2015 04:54 am
Are you one of those people that claim it's only 5% of the delta v to orbit?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: aga on 02/19/2015 05:36 am
economic viability of the complete system, including engines and airframe.

that was done by others, not by rel... eg. esa, london economics, etc
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 02/19/2015 06:13 am
economic viability of the complete system, including engines and airframe.

that was done by others, not by rel... eg. esa, london economics, etc

It was done by REL.  All the projections come from REL.  A small group from ESA did a short audit of the REL plans to see if there was an obvious show-stopper.  They said there wasn't a showstopper they could see.  They didn't claim to know REL's projections were all correct.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 02/19/2015 07:34 am
REL is the one who chose to design it for an SSTO vehicle.  They chose to optimize it for that role rather than as part of a reusable first stage of a two-stage launch system, which would be the more conservative choice and give them more margin and require much less in the way of pushing the edge of what technology can do.
Which would in fact have doubled the development budget as they would had to look at 2 vehicles and the testing around hypersonic separation. The last attempt at which was IIRC the SR71/M4 drone separation tests.

This is from the man who's worried about "too many unknowns."  :(

You need to stop making assertions as fact. They make you look untrustworthy.
Quote
And everything gets cheaper when things are smaller.
You work in a Silicon valley start up and you aren't aware of price inflation between the last and next generation of wafer fabs as they've gone from about about 33 to 14nm?

Or the time and effort involved when you go from the piping in the 1960's Aerospace Plane (about 1cm) to the 1mm used in REL HX's.

Or REL estimate that a scaled down LH2 turbo pump (to give the same chamber pressure) for a small scale SABRE would eat abut £250m of the budget alone as engineering bearings to run about 12x faster than the full scale unit (in LH2) is much harder.

No smaller often means cheaper, but not always. Smart engineers are aware of this and plan accordingly.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 02/19/2015 09:25 am
I don't see them claiming that their plan is set in stone.

Claiming, no. Acting, yes. They are designing payloads and space stations and Mars missions around the size/capacity of the Skylon payload bay. (Not to mention a hypersonic passenger plane.) And Bond rejects out of hand any suggestions that Skylon may not be the optimal design (as John echoes, above). If you were an "airframer", would you get mixed up with an engine company which behaves like that? Or wait until they fail and just licence the engines from whoever buys the IP, and develop your own clean-sheet design?

To me, it's like some who wants to develop the world's first jet engine. So far they have one compressor fan. But they've not only designed the rest of the engine, and designed the entire airliner around that engine, and insisted it's the only possible design, but they are proposing new airport designs based around the door spacing on that proposed airliner for the proposed engine for which they have (after 20 years) only built a single compressor fan.

But you dare suggest they are being a bit premature...

REL is the one who chose to design it for an SSTO vehicle. They chose to optimize it for that role rather than as part of a reusable first stage of a two-stage launch system
Which would in fact have doubled the development budget as they would had to look at 2 vehicles

{sigh} Why is this idea so prevalent in aerospace?

Two is more than one, so therefore it must cost twice as much to develop an aircraft to carry freight between cities and a truck to ferry between individual customers and the airfreight terminals than to develop a single vehicle which can fly between cities but land directly on the customers' driveways. Must. Because two is more than one.

Quote
and the testing around hypersonic separation.

Only if they were stupid.

When Chris is suggesting smaller stepping stones, when that's the entire premise of his argument, why would you assume he would be suggesting the hardest possible version of TSTO?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 02/19/2015 10:42 am
I don't see them claiming that their plan is set in stone.

Claiming, no. Acting, yes. They are designing payloads and space stations and Mars missions around the size/capacity of the Skylon payload bay. (Not to mention a hypersonic passenger plane.) And Bond rejects out of hand any suggestions that Skylon may not be the optimal design (as John echoes, above). If you were an "airframer", would you get mixed up with an engine company which behaves like that? Or wait until they fail and just licence the engines from whoever buys the IP, and develop your own clean-sheet design?

If one looks with a hostile attitude one can twist quite normal behaviour into something sinister.

Engines do really determine what kind of aeroplane can be built - it has always been that way around in the aircraft world I believe (I'm no expert but reading the history of flight makes it pretty obvious). So yes, the airframer is going to have to accept that they can't make an airframe any size or any shape they like.  They still have freedom to ignore REL's design if they have to a reason to.  Why would they be sulky about something that has been a fact of life in the aerospace industry since the beginning?

REL designed Mars missions to show themselves that it was possible to do such a thing with the design.  If it hadn't been then that would have meant there was something basically wrong with the whole idea and it would have to be modified.

Similarly they have studied how to launch satellites and boost them into GEO. Without doing this, who would invest? It's part of designing something that you put it through it's imaginary paces before you build it rather than afterwards. Surely? Would you consider it responsible not to? Surely this has to be done repeatedly with more and more detail until the final article does it for real?

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Krevsin on 02/19/2015 11:32 am
REL is the one who chose to design it for an SSTO vehicle.  They chose to optimize it for that role rather than as part of a reusable first stage of a two-stage launch system, which would be the more conservative choice and give them more margin and require much less in the way of pushing the edge of what technology can do.
Which would in fact have doubled the development budget as they would had to look at 2 vehicles and the testing around hypersonic separation. The last attempt at which was IIRC the SR71/M4 drone separation tests.
I'm not an expert on any of this so feel free to correct me, but wouldn't it make more sense to develop a TSTO Skylon in such a way that the skylon makes a suborbital hop and, once outside the brunt of the atmosphere, open the cargo bay and deploy an upper stage to which the payload is attached?

In fact, hasn't something similar to this concept been proposed in this (http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=30547.0;attach=535740) study by Mark Hempsell?

It'd certainly be less complicated than staging inside the atmosphere at hypersonic velocities IMO.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 02/19/2015 11:51 am
Claiming, no. Acting, yes. They are designing payloads and space stations and Mars missions around the size/capacity of the Skylon payload bay.
Another new member who's appeared from nowhere. Welcome to the forum.

Actually you have REL's process backwards.

They run these projects to ensure that a)The existing Skylon iteration is big enough to accommodate potential customers or b)What size or other part of it needs to be re-sized to to accommodate them. Skylon is on the "D" level of its iteration so it's actually been through 4 major design cycles, although C was the first public design.
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(Not to mention a hypersonic passenger plane.)
Then why mention it? It's a separate project that was sponsored by the EU.
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And Bond rejects out of hand any suggestions that Skylon may not be the optimal design (as John echoes, above). If you were an "airframer", would you get mixed up with an engine company which behaves like that? Or wait until they fail and just licence the engines from whoever buys the IP, and develop your own clean-sheet design?
What a delightful plot for a James Follet novel.  :)

IRL Engine makers make engines and airframers make airframes. The situation is somewhat analogous to that still paper airplane the "SR72." do you expect LM to wait till Aerojet fails and buy up their IP as well?
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To me, it's like some who wants to develop the world's first jet engine. So far they have one compressor fan. But they've not only designed the rest of the engine, and designed the entire airliner around that engine, and insisted it's the only possible design, but they are proposing new airport designs based around the door spacing on that proposed airliner for the proposed engine for which they have (after 20 years) only built a single compressor fan.
Your PoV would make a lot more sense if there was someone out there saying "no, that's not how a partially air breathing HTOL SSTO should be built."

Except there is no one arguing that and the Skylon design makes good sense. In fact when NASA looked at combined cycle vehicles using TBCC they came up with a remarkably similar vehicle
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But you dare suggest they are being a bit premature...
{sigh} Why is this idea so prevalent in aerospace?

Two is more than one, so therefore it must cost twice as much to develop an aircraft to carry freight between cities and a truck to ferry between individual customers and the airfreight terminals than to develop a single vehicle which can fly between cities but land directly on the customers' driveways. Must. Because two is more than one.
Perhaps because the launch problem isn't like your rather elaborate metaphor?

You might like to study the real 2 stage vehicles proposed under the original Shuttle programme. Or you might like to glance through the thread I started on the idea of a "Triamese" shuttle.
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and the testing around hypersonic separation.

Only if they were stupid.

When Chris is suggesting smaller stepping stones, when that's the entire premise of his argument, why would you assume he would be suggesting the hardest possible version of TSTO?
You clearly know his mind better than we do. Perhaps you could explain his thinking?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 02/19/2015 12:07 pm
I'm not an expert on any of this so feel free to correct me, but wouldn't it make more sense to develop a TSTO Skylon in such a way that the skylon makes a suborbital hop and, once outside the brunt of the atmosphere, open the cargo bay and deploy an upper stage to which the payload is attached?

In fact, hasn't something similar to this concept been proposed in this (http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=30547.0;attach=535740) study by Mark Hempsell?

It'd certainly be less complicated than staging inside the atmosphere at hypersonic velocities IMO.
Yet another new forum visitor. You really are coming out of the woodwork today.  :) Welcome.

Your line of reasoning leads to the logical conclusion that the simplest process is to not stage at all does it not?

I'm not sure where you're reading about sub orbital staging in the paper you cited.  Hempsell in a previous thread mentioned REL had looked at this. REL studies indicated a sub orbital flight could put 30 tonnes into LEO if the payload could supply sufficient delta V to circularise it's orbit.

IIRC no one they've been talking to said they really need this and further studies showed that the window between doors open, payload deployment and doors closed before re entry began was tight. With no one actually asking for it and little margin for error they deleted it as an option from the latest issue of the Skylon user manual.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Krevsin on 02/19/2015 12:41 pm
Your line of reasoning leads to the logical conclusion that the simplest process is to not stage at all does it not?
Not really. In the "suborbital + kick stage to orbit" TSTO method, your primary carrier doesn't need to have quite as thin a mass margin than in a fully SSTO vehicle. It gives you more room to work with.

The only reason it goes above the atmosphere is to avoid the trouble with staging at hypersonic velocities while in the thick atmosphere.

I'm not sure where you're reading about sub orbital staging in the paper you cited.
Sorry, my bad. What I mostly meant with the study was that it contained the "fluyt" stage which could be scaled down from a GEO/Lunar transfer stage to a orbital circularization stage.

Of course, the down side of all this kick stage mallarkey would be a smaller space for payload in the cargo bay, but given the larger mass fraction thus allowed, the cargo bay would have (probably) been expanded somewhat. I'm unsure on this.

IIRC no one they've been talking to said they really need this and further studies showed that the window between doors open, payload deployment and doors closed before re entry began was tight. With no one actually asking for it and little margin for error they deleted it as an option from the latest issue of the Skylon user manual.
Those were some issues that I have also considered, but given the fact that Skylon is a reusable system, in case of running the margin too close for comfort, the people launching could easily simply opt not to deploy the payload and simply return Skylon to the ground, with the payload intact, and try again after adressing any issues which might have cropped up.

So, while the deployment window is short, I believe it is manageable.


The real issue with this TSTO concept I've outlined (at least from what I can tell) lies in getting the Skylon back to its launch site, as that would probably require prohibitive amounts of fuel so two facilities, one for launch and one for landing would most likely be required. Which would probably run the infrastructure maintenance bill through the roof.

Yet another new forum visitor. You really are coming out of the woodwork today.  :) Welcome.
Thanks.  :)
I've been registered here a while, but I mostly prefer to lurk as I often feel like I don't really have anything to add to the conversation.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 02/19/2015 02:45 pm
Not really. In the "suborbital + kick stage to orbit" TSTO method, your primary carrier doesn't need to have quite as thin a mass margin than in a fully SSTO vehicle. It gives you more room to work with.

The only reason it goes above the atmosphere is to avoid the trouble with staging at hypersonic velocities while in the thick atmosphere.
You're operating under a very big misunderstanding.

Thin mass margins apply to vertical take off SSTO's and all rocket HTOLs.

Skylon is neither. Air breathing to Mach 5.5 raises the average Isp to something like 5x what you get from an all rocket design and hence a much bigger payload mass fraction. Roughly speaking SABRE costs 20 tonnes to buy 100 tonnes off the LOX mass budget.  Being HTOL it also avoids needing SABRE thrust to be > than it's T/O mass. They can be about 1/3 that and (like ordinary conventional aircraft) get the job done.

That does 2 things. 1) Gives a mass fraction in the possible range for an HTOL SSTO and 2) Gives a payload fraction as good as an ELV of the same GTOW. This has never happened before. SSTO proponents have always expected to take a payload reduction and make up for it with more launches.  Skylon does not need to do this.

2) matters when you have to raise funds since why would people pay for a system that cannot at least match what a TSTO does already?
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Sorry, my bad. What I mostly meant with the study was that it contained the "fluyt" stage which could be scaled down from a GEO/Lunar transfer stage to a orbital circularization stage.

Of course, the down side of all this kick stage mallarkey would be a smaller space for payload in the cargo bay, but given the larger mass fraction thus allowed, the cargo bay would have (probably) been expanded somewhat. I'm unsure on this.
Flyt can't fit in the cargo bay in one piece. It's designed to work only in vacuum. The Skylon Upper Stage is designed to take payloads from LEO to GTO before returning and is now included in the budget.
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Those were some issues that I have also considered, but given the fact that Skylon is a reusable system, in case of running the margin too close for comfort, the people launching could easily simply opt not to deploy the payload and simply return Skylon to the ground, with the payload intact, and try again after adressing any issues which might have cropped up.

So, while the deployment window is short, I believe it is manageable.
I'll quote what Hempsell, who was with REL at the time, had to say.

Advanced Concepts / Re: The Reaction Engines Skylon Master Thread (4)
« on: 10/17/2014 04:23 PM »

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Quote from: lkm on 10/17/2014 03:19 PM

    With regards to Skylon forming  part of a military weapons platform, the Skylon user manual does detail the suborbital deployment of payloads of up to 30mt at Mach 20. Couldn't a module be designed to rack launch a load of HTV-2 like prompt global strike weapons using that mission mode?
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Sorry; sub-orbital deployment is off the menu and is not in the latest issue of the Users' Manual.  There were problems making the reentry work and, as there was no identified use for it, we gave up trying to find a solution.  We found the very low orbit deployment worked better for maximising the payload.

A further point is that the front payload mounting interface is now designed for a maximum of 17 tonnes so at the moment that is the biggest payload that can be carried regardless of where it is deployed.

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The real issue with this TSTO concept I've outlined (at least from what I can tell) lies in getting the Skylon back to its launch site, as that would probably require prohibitive amounts of fuel so two facilities, one for launch and one for landing would most likely be required. Which would probably run the infrastructure maintenance bill through the roof.
Yes and no. In air breathing mode Skylon is about 150 tonnes lighter, so a conventional runway could handle the landing.  Skylon is also a pretty good glider. The wings look too small but that's because the body is so big and so empty. It's a lot more aerodynamic than the Shuttle was. REL expect the D revision to have transatlantic range in air breathing mode. LH2 is qutie expensive at around $8.29/Kg but that would still mean a fully fueled fly back would be less than $500k.

The real problem is likely to be takeoff noise from the down range airport. Even 150 tonnes lighter and substantially throttled back a Skylon on takeoff will be very loud.  :(
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Yet another new forum visitor. You really are coming out of the woodwork today.  :) Welcome.
Thanks.  :)
I've been registered here a while, but I mostly prefer to lurk as I often feel like I don't really have anything to add to the conversation.
SABRE/Skylon is now in it's 5th thread. There's been a lot of discussion and a lot of ideas have come up (sometimes on several occasions). The site search function is very useful for finding out if something has come up before. Sadly it seems there's no way I can find to search a whole thread, rather than 1 page at a time.  :(

Electromagnetic catapult launch, catapult launch up a mountain, landing on a shallow water pool (to spread the load) have all come up already. 

Happy reading.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Krevsin on 02/19/2015 02:56 pm
I see. Well, thanks for the info.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 02/19/2015 03:48 pm
The people working on Skylon have been working on the idea for decades.  They are certainly dedicated and well-meaning, and they have some competence.  But they have been working on theory and small components.  They don't have experience in system integration.  They haven't built real flight hardware.  They haven't seen a system from concept through to all the inevitable compromises necessary to make a practical system.

I don't have a biography to hand of each one of them but I suggest that it's a sweeping statement to say that they have no experience in system integration.  At the very least some of them are veterans of Blue Streak and others of the aerospace industry.

But that goes for almost any aerospace start-up. Among its employees you would expect to see some veterans from other aerospace firms - but that does not mean that the "organizational experience" as a whole translates to this new organization. 

In other words SpaceX was "unproven" until they actually flew something successfully. (That would be the F9 btw :) )

Got it.
They are an engine company not an airframe company.   Let the airframe company use its great institutional experience for its part of the work.

That's fine, but this engine company is making projections about the performance and economic viability of the complete system, including engines and airframe.

??? And your point? Engine companies have done that before, quite often and often with "notional" airframes to boot rather than ones that have been actually researched. Pratt-&-Whitney, GE, Mardquart to name a few. Some of them have published "studies" that made claims to those factors for everything from SCramjets to StrutJet systems. Occasionally they will actually "quote" airframe manufacturers but more often than not (since involving them costs money) they will "interpret" data from other airframes and or "other" source material.

There'd be no shame in their saying "we don't know yet".

Isn't there? After all, yourself being an example, there are people who are taking them to task FOR "not-knowing" what they are talking about when they DO talk about subjects and methods they have experience with :)

They are making, (as I pointed out many "engine" companies do) educated projections based on available knowledge and assumed performance with some very deep margins for the assumptions involved.

Actually, that demonstrates my point quite well.  DC-X never progressed to an operational vehicle.  It was never more than a sub-scale technology demonstrator.  Working on DC-X wouldn't give any experience with the very difficult transition from technology demonstration to a system that is economically successful as an operational system.

And "worked on" isn't the same as being in charge.

Actually what it "demonstrates" is you don't even have a firm grasp on what you mean to say and therefore keep moving the goal posts as you argue :)

The DC-X was, if you'll recall a "SSTO-Rocket-Powered-subscale demonstrator vehicle with NO intention other than demonstrating several ancillary "functions" of such a vehicle not any of the "substantive" functions thereof.

It "proved" that VTVL and fairly "quick" operational turn around were possible on a vehicle that faced nor addressed none of the substantial challenges to actual operational flight.
"Learning" experience here was consistent with operations and data acquisition for an LH2 rocket engine over the lifetime of the program and various issues and questions relating to those operations. Directly applicable to what amounts to a rocket powered air/LH2 engine such as Skylon.
(Note: Also applicable was the experience gained from that program which was directly related to the "future development" of a fully operational vehicle as proposed by the manufacturer of the vehicle and this was one of the reasons that led Mr. Hempsell to conclude that with current technology a solely rocket powered SSTO vehicle wasn't viable and turned his interest towards air-breathing designs :) )

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REL is the one who chose to design it for an SSTO vehicle.  They chose to optimize it for that role rather than as part of a reusable first stage of a two-stage launch system, which would be the more conservative choice and give them more margin and require much less in the way of pushing the edge of what technology can do.

And everything gets cheaper when things are smaller.

And they "choose" to do so due to issues with scaling of the engine and LH2 propellant. They also DID run a trade study on a TSTO versus an SSTO vehicle and found that the favored design was an SSTO rather than breaking the design into a fully-TSTO design.
(I should point out that "technically" the Skylon IS a fully-reusable TSTO design since the "target" market is GTO/GEO and not LEO so a "second" stage is needed to complete the mission. A "fully-reusable" baseline TSTO therefore would require a "third" stage of similar design to achieve the stated goal as well)

Further while it IS true that TSTO designs have excess "margin" to allow for possible design and operational changes they also have those margins only to a limited extent as has been shown by the SpaceX Falcon-9 design. Referencing the trades that REL did showed that the "margins" allowed by the current suggested design of the Skylon allow very similar margins while using the SSTO design over the increased complexity and cost of a TSTO design.
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Getting to Mach 5.5 isn't the challenge.  They still have to get to Mach 25 to make orbit.  True, in some ways it's easier if they're only air breathing to Mach 5.5.  But in other ways it's harder.  They have to carry much more oxidizer, and their engine has to work well in both air-breathing and rocket mode.  Going from Mach 5.5 to Mach 25 in rocket mode (with some of that rocket mode in the dense part of the atmosphere at Mach 5.5) means they need a very good mass fraction.

Note that while "you" don't think they have thought of this "issue" the plain fact is they have done a LOT of work on this and have come to the conclusion that a ROCKET BASED rather than some form of turbine-engine based engine design actually fits this criteria. Funny enough that was a conclusion reached by most researchers in the field by the late 1950s. Unfortunately several mis-assumptions crept into the field at that same time which REL have managed to avoid. (Such as a requirement for air-liquification for rocket engine use rather than deep cooling, ramjets being "required" to reach speeds between Mach-3 and Mach-6, and the "need" for SCramjet engines to allow high hypersonic air-breathing flight, etc)

The SABRE is a "good" rocket engine that can be operated "decent" air-breathing engine from a standing start to around Mach-5.5. From there is goes back to being a "good" rocket engine using on-board propellant to go from Mach-5.5 to around Mach-25 and orbit. The rocket equation (modified) shows this has enough performance to allow some pretty hefty mass-margin and a very robust mass-fraction with the given design. Rocket engines, and materials science have come a long way from the 1950s and thankfully REL never even considered using multiple engine types to close their design :)

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Like I said, they don't have exactly the same challenges NASP had, but they have very great challenges, and I think they're at a comparable level of difficulty.  Apparently, others think they are too, which is why others are continuing SCRAMJet research and development.

SCramjet research and development continues because of the "promise" of hypersonic flight within the atmosphere despite the problems and issues of such flight. In 'theory' a SCramjet can fly to beyond Mach-24 and that 'theory' looks really, really good despite some obvious flaws in the full logic chain. (As an example, its obvious that internal airflow within a SCramjet at speeds of around Mach-15 become so hot that even with hydrogen fuel further operation {acceleration} is unlikely. Operations above that speed induce 'plasma' like flow where NO amount of additional fuel will continue operations but that's not ever mentioned when SCramjets research and development is discussed.

"Truth" is that REL is working on and from the point where air-breathing, rocket based, acceleration engines was "going" before it was side-tracked in the 1950s/60s. The "challenges" are significantly less since the vehicle is not designed to nor will it remain in the atmosphere any longer than needed.

"Smaller-is-cheaper" is pretty much an aerospace "law" for intents and purposes and yes it would be "nice" if REL could do a demonstrator first but there is a minimum size for a fully operational SABRE engine and LH2 propellant system capable of supporting the same. And yes its "tricky" because LH2 is required for the deep cooling effect which is the basis of the system, but that's actually a requirement, not a choice. Liquid Hydrogen systems do not as a rule lend themselves to "small" systems in any sort of "operational" use. The only way REL could build a significantly "smaller" system would be to forgo the use of LH2 for a more compact but MUCH less capable propellant and they have already PROVED the engineering of an LH2 heat exchanger system so what would be the point?

REL plans on "demonstrating" a full sized SABRE engine operationally for the full flight duration and then moving on to an actual airframe designed and built with the help of a fully "proven" builder. But in order to do the "testing" necessary for a "full-duration" test of the engine they need to have an idea of what the airframe and its effects on performance will be. Not even REL is expecting the Skylon to turn out EXACTLY as they propose but until an airframe company steps forward and proposes their own idea with accompanying data REL has to make its own way. (And note that while others HAVE proposed different designs REL has not outright rejected those designs)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 02/20/2015 06:21 am
In other words SpaceX was "unproven" until they actually flew something successfully. (That would be the F9 btw :) )

Actually it'd be the F1.

SpaceX actually did the whole incremental development thing. Are still doing it. And I think it explains a lot about their success. Imagine they had tried to jump directly to MCT/Raptor. (Even then, I think they are still skipping necessary stepping stones.)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 02/20/2015 08:06 am
I wonder if we can move the discussion on by agreeing on a few things.

1)Reaction Engines Limited is not SpaceX.

2)It's development approach is completely different to that of SpaceX.

3)REL are not going to change their development approach because of anyone's opinion on the matter.

4) SpaceX have built a very fine ELV for (by government cost modelling standards) a very modest budget.

5) To be a valid comparison for Skylon any competitor has to be a) Fully reusable b) Able to deliver at least 15 tonnes to LEO c) Able to deliver at least 6 tonnes to GTO. If a candidate vehicle cannot manage this then it's not a valid comparison.

6)The arguments that "It's never been done before" or "Others have tried and failed" are in fact the reason why startups are started.  Their founders believe something can be done which has either not been done before or where previous attempts have failed. That definition applies to REL, SpaceX, XCOR, Blue and in fact any start up trying to do something that has never been done or never been done successfully before, probably including whatever start ups some of the other posters here are working for.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Lars-J on 02/20/2015 08:19 am
5) To be a valid comparison for Skylon any competitor has to be a) Fully reusable b) Able to deliver at least 15 tonnes to LEO c) Able to deliver at least 6 tonnes to GTO. If a candidate vehicle cannot manage this then it's not a valid comparison.

You're right. It's not a fair comparison. One is flying, hopefully partially reused soon. The other... is just something on a paper.
 - A) Skylon is not "fully reusable", because it does not exist.
 - B) Skylon can not "deliver at least 15 tonnes to LEO", because it does not exist.
 - C) Skylon can not "deliver at least 6 tonnes to GTO", because it does not exist.

Are you catching my drift? It's always easy to make a paper project look better in comparison to any existing hardware. Reality can be slightly more difficult.  :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 02/20/2015 09:14 am
4) SpaceX have built a very fine ELV

And REL have built a heat exchanger.

They have not built SABRE and are nowhere near ready to build even a test version of SABRE. They have not built and are not building Skylon. They have built a heat exchanger. Can we agree on that? I think that would move any discussion on much more.

Whereas insisting...

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5) To be a valid comparison for Skylon any competitor has to be a) Fully reusable b) Able to deliver at least 15 tonnes to LEO c) Able to deliver at least 6 tonnes to GTO. If a candidate vehicle cannot manage this then it's not a valid comparison.

...seems to be the very thing that prevents any progress in the discussion.

Chris's post (which started the discussion that so far dominates Part 5) was asking if Skylon might not the best development path for REL's proposed technology. They are trying to jump too many steps ahead of themselves. Hence 20 years and all they have is a heat exchanger. Surely after all this time, we're allowed to ask, "Is this the best path?" Is that question so offensive to you?

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6)The arguments that "It's never been done before" or "Others have tried and failed" are in fact the reason why startups are started. Their founders believe something can be done which has either not been done before or where previous attempts have failed.

REL is trying to develop a fundamentally new type of engine. A radical air-breathing jet engine/rocket hybrid. When you are doing something so untried, so deep in unexplored territory, you don't try to lock down the end design of a vehicle that might use that engine. Simply because you can't. That's all people are saying. That's what you can't seem to move beyond.

REL doesn't and can't know the actual performance of any eventual engine. None exist, and the very concept is so new and untried that there's no reasonable extrapolation from prior technology. Therefore, without that, they cannot possibly design a vehicle yet. So the idea that this early in the process they are designing end-user missions around the size of the payload bay of that vehicle is bonkers.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 02/20/2015 10:58 am
And REL have built a heat exchanger.

They have not built SABRE and are nowhere near ready to build even a test version of SABRE. They have not built and are not building Skylon. They have built a heat exchanger. Can we agree on that? I think that would move any discussion on much more.
So far the only person arguing that point is you with yourself. Strawman arguments tend to be the starting point for trolls. You might like to keep that in mind.
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Whereas insisting...
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5) To be a valid comparison for Skylon any competitor has to be a) Fully reusable b) Able to deliver at least 15 tonnes to LEO c) Able to deliver at least 6 tonnes to GTO. If a candidate vehicle cannot manage this then it's not a valid comparison.

...seems to be the very thing that prevents any progress in the discussion.
Not at all. This is REL's choice. It's what they are planning to build since they revised the design in 2010. Please note the thread title.
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Chris's post (which started the discussion that so far dominates Part 5) was asking if Skylon might not the best development path for REL's proposed technology. They are trying to jump too many steps ahead of themselves. Hence 20 years and all they have is a heat exchanger. Surely after all this time, we're allowed to ask, "Is this the best path?"
And it has been asked over the last 4 threads. But since you seem so concerned about the design, what's your design for a SABRE carrying vehicle?
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Is that question so offensive to you?
Not in the slightest. The number of posts I've read have enhanced my tolerance of even the most stupid of comments.
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REL is trying to develop a fundamentally new type of engine. A radical air-breathing jet engine/rocket hybrid.
Actually not that radical, in fact much less radial than the LACE concepts running around the National Aerospace project (the original one in the early 60's). Using William Eschers taxonomy it even has a name. A "Deeply pre cooled air turbo rocket."
Trouble was no one could get the frost control to work in the inlet heat exchanger.   :(
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When you are doing something so untried, so deep in unexplored territory, you don't try to lock down the end design of a vehicle that might use that engine. Simply because you can't.
And yet that was exactly what SpaceX did with the F9. There's a difference between Science and Engineering. REL have done Science to do Engineering. Spacex have done Engineering, now they are doing Science. And Science is not predictable
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That's all people are saying. That's what you can't seem to move beyond.
No that's what 2 people are posting. And what other people with more experience in this area are posting is that actually engine companies in the aircraft business do this regularly.


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REL doesn't and can't know the actual performance of any eventual engine. None exist, and the very concept is so new and untried that there's no reasonable extrapolation from prior technology. Therefore, without that, they cannot possibly design a vehicle yet. So the idea that this early in the process they are designing end-user missions around the size of the payload bay of that vehicle is bonkers.
Wow.  ???
Just wow.

That statement alone tells me you have no understanding of the thermodynamics underlying all engines (rocket, Diesel, gas turbine, ram or SCramjet), dating from the mid 1700s, and even less about the changes in computer modelling over roughly the last 65-70 years.  :o

You appear to think engine design (of all types) is stuck in the 1950's, where cut-and-try was the only option.

Thank you for that. It means I won't have to waste a second more responding to you. Good bye.  :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 02/20/2015 12:38 pm
4) SpaceX have built a very fine ELV

And REL have built a heat exchanger.

They have not built SABRE and are nowhere near ready to build even a test version of SABRE. They have not built and are not building Skylon. They have built a heat exchanger. Can we agree on that? I think that would move any discussion on much more.

It seems to me that this debate is about the attitude we should all have more than about facts since I can't remember anyone suggesting that REL have built things they haven't built.

I'm interested in what happens assuming they get things mostly right or what they might do if this or that issue turns out to be more difficult  because the alternative is that they go bust and the world is the same as before which is a non-story - why discuss it?

We might as well mention that lots of people have built rockets before but this heat exchanger is exceptional so it speaks for their ability to come up with something unheard of and get it done right.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 02/20/2015 01:35 pm
To start off the new thread, here's a summary of my own reasons for being skeptical about Skylon.  Some of these views are probably shared by other skeptics.  Feel free to reply with opposing views; hopefully, this will help clarify exactly where opinions differ and help undecided readers of these forums see both sides and make up their own minds.

First off, I don't think there's a known flaw in Skylon that definitely makes it impossible.  It's not like a perpetual motion machine that violates known laws of physics.  My issue with Skylon is that there are too many unknowns and the proponents of Skylon assume those unknowns will work out, while history shows this is seldom the case.  There are enough unknowns and enough projections that seem very optimistic to me that the odds of Skylon actually achieving its goals seem remote to me.

The people working on Skylon have been working on the idea for decades.  They are certainly dedicated and well-meaning, and they have some competence.  But they have been working on theory and small components.  They don't have experience in system integration.  They haven't built real flight hardware.  They haven't seen a system from concept through to all the inevitable compromises necessary to make a practical system.

I don't think you are fully aware of the background the REL team. Mark Hempsell for example worked on the DCX.
http://forum.nasaspaceflight.com/index.php?topic=19127.msg493088#msg493088

Actually, that demonstrates my point quite well.  DC-X never progressed to an operational vehicle.  It was never more than a sub-scale technology demonstrator.  Working on DC-X wouldn't give any experience with the very difficult transition from technology demonstration to a system that is economically successful as an operational system.

And "worked on" isn't the same as being in charge.

Except that wasn't your point at at, your point was quite clear. That people in REL lacked "experience in system integration", "haven't built real flight hardware", and "haven't seen a system from concept through to all the inevitable compromises necessary to make a practical system". The DC-X clearly meets your original point which had no requirement of being in charge or the end system becoming operational. Other projects that meet that criteria plus your newly added one of operational status are the EJ200, Spey and RB211 which Richard Varvill and John Scott Scott worked on, respectively.



The team at REL has consistently proposed building a large-scale single-stage-to-orbit system.  That shows poor judgement, in my opinion.  SpaceX started with Falcon 1.  Then then moved to a full-expendable Falcon 9.  Now they are working on perfecting reuse of only the first stage.  Along the way, they have learned many lessons and constantly changed their plans, all while retaining their goal of greatly reducing the cost of launch.  I believe that kind of incremental, flexible approach is very effective.  It is the opposite of the REL approach.  With REL going directly for a huge, single-stage-to-orbit system, there is little room to learn operational lessons and change plans.  And Skylon is so much different from existing systems it is very likely to need far more flexibility for lessons learned than Falcon.

SABRE is a SSTO engine, I'm not sure what intermediate stage there can be for engine explicitly designed to take a single stage into orbit. I can't imagine designs cost get significantly smaller by making a smaller version.

REL is the one who chose to design it for an SSTO vehicle.  They chose to optimize it for that role rather than as part of a reusable first stage of a two-stage launch system, which would be the more conservative choice and give them more margin and require much less in the way of pushing the edge of what technology can do.

And everything gets cheaper when things are smaller.
When are you proposing to stage this notional TSTO? Inside the atmosphere so you can use a simpler non rocket mode SABRE losing LOX tanks from the first stage or outside still using SABRE?
 Are you carrying the second stage internally or externally? If externally how are managing the damage that does to the aerodynamics and thermal protection? If internal how are making the vehicle trimable given the damage that does?   
What engine is powering the second stage?
How does any of that make the development of SABRE cheaper? Either you're proposing using the SABRE design as is, or you're suggesting development of a second engine, on top of SABRE, without a pure rocket mode neither of which can be cheaper for REL as an engine developer than just building SABRE.


There have been many programs with similar or lesser optimistic goals that have failed.  The U.S. National Aerospace Plane had far more resources available and a similar level of technological challenge, and it failed.  Note that I'm not saying the details of the technological challenge are similar -- they are not.  But the programs are similar in having a goal that required many unknowns to be overcome and having people with some competence in specific areas convinced they could overcome them.
The technical challenge of airbreathing to Mach 18 is clearly of a vastly higher level than airbreathing to Mach 5.5 and the number of unknowns in geting to Mach 18 in 1984 far greater than achieving Mach 5 thirty years later.

Getting to Mach 5.5 isn't the challenge.  They still have to get to Mach 25 to make orbit.  True, in some ways it's easier if they're only air breathing to Mach 5.5.  But in other ways it's harder.  They have to carry much more oxidizer, and their engine has to work well in both air-breathing and rocket mode.  Going from Mach 5.5 to Mach 25 in rocket mode (with some of that rocket mode in the dense part of the atmosphere at Mach 5.5) means they need a very good mass fraction.

Like I said, they don't have exactly the same challenges NASP had, but they have very great challenges, and I think they're at a comparable level of difficulty.  Apparently, others think they are too, which is why others are continuing SCRAMJet research and development.
I can't help feel that rocketry (successfully putting things in orbit since 1957)  is somewhat better understood that Scramjets ( someday soon we'll reach ten minutes cumulative flight time). Who is seriously researching scramjets for anything other than hypersonic cruise? Also please name these other people who think that the development challenges of NASP in 1984 are of comparable difficulty to the challenges of Skylon in 2015.

The X-33/VentureStar is another launch program that had optimistic goals and failed.  I think that X-33/VentureStar looked far more realistic at its outset, with less of a techonological leap required, than Skylon today.  And yet it failed because of the engineering details in turning the theory into reality.

X-33 didn't fail, it was cancelled due to a change in administration, just as many Clinton era space programs were cancelled by the Bush administration. What many people forget is that the X-33 was just a rocket powered x-plane like the X-15, like the X-15 it had a ton of not flown before technology some of which had teething problems, and like the X-55 if it had flown it would have provided invaluable hypersonic flight data.

Getting into the details of X-33 is off topic, but lets just say that opinions differ about X-33 -- many people believe it was cancelled because the progress up to that point indicated it was not able to meet its projections and wouldn't have been viable.

Many people believe that VentureStar wasn't viable, but I don't think anybody believes the X-33 couldn't have flown and gathered useful data. The X-33 wasn't VentureStar, VentureStar was a powerpoint, X-33 was an active x-plane project with a similar budget and goals to the X-15. The X-15 wasn't a failure because it had no follow on project so why  should the X-33? When the X-15 first flew it didn't have it's intended engine yet because it wasn't ready, so why should the X-33 not have been given the same leeway? Like I said, there was a change in administration, a desire to cancel and repudiate the projects of the previous one, people obliged.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Lars-J on 02/20/2015 03:29 pm
There's a difference between Science and Engineering. REL have done Science to do Engineering. Spacex have done Engineering, now they are doing Science. And Science is not predictable

This paragraph deserves some kind of award. ;D It should be smooth sailing for REL now, then!  ;)

EDIT: To offer a more substantive response. I don't think the line between science and engineering exists as you think it does. And what scientific breakthroughs have REL done? Their pre-cooler work would be classified by most as an impressive piece of engineering.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 02/20/2015 03:53 pm
In other words SpaceX was "unproven" until they actually flew something successfully. (That would be the F9 btw :) )

Actually it'd be the F1.

SpaceX actually did the whole incremental development thing. Are still doing it. And I think it explains a lot about their success. Imagine they had tried to jump directly to MCT/Raptor. (Even then, I think they are still skipping necessary stepping stones.)

My bad my source list had the F1 flights as "partially successful" :) And actually they didn't as they "developed" everything from scratch and tested it as they built. Which is technically what REL is also planning on doing but which Chris is ignoring :)

Full scale engine is next and THEN maybe a full scale test vehicle. This is really more how aircraft are built than rockets which is of course the main point in their development plans.

But "my" point still stands that by the criteria Chris used, SpaceX was an "unproven" company despite all their "incremental" testing until they actually flew a successful, full-up flight :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Kansan52 on 02/20/2015 04:16 pm
I'm confused.

It has been posted that all that REL has built is a heat exchanger. My understanding is the heat exchanger is the linchpin. The rest of the engine is based on existing technology.

Is that incorrect?

If the heat exchanger is the linchpin idea is correct, then REL is suffering from NBNBR (No Bucks, No Buck Rogers - Bucks meaning money not dollars). Things will be slow due to money issues, not technology issues.

To recap, REL's heat exchanger is the show stopper and REL has accomplished that, the engine is based on known technology working with the heat exchanger (not easy but not necessarily ground breaking), and REL could work faster is they has more money.

That my understanding.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 02/20/2015 05:13 pm
I'm confused.

It has been posted that all that REL has built is a heat exchanger. My understanding is the heat exchanger is the linchpin. The rest of the engine is based on existing technology.

Is that incorrect?

If the heat exchanger is the linchpin idea is correct, then REL is suffering from NBNBR (No Bucks, No Buck Rogers - Bucks meaning money not dollars). Things will be slow due to money issues, not technology issues.

To recap, REL's heat exchanger is the show stopper and REL has accomplished that, the engine is based on known technology working with the heat exchanger (not easy but not necessarily ground breaking), and REL could work faster is they has more money.

That my understanding.

They (REL) have built and tested a deep-cooled air/hydrogen rocket engine which would "technically" be the "heart" of the SABRE and built and tested a heat exchanger which was tested under simulated supersonic conditions (using the exhaust of a running jet engine into the intake of the HE) which was the 'key technology' to the deep-cooled engine set up. The rest of the engine is pretty much adaption of off-the-shelf technology for turbojet compressors.

Your also correct that the main reason REL's progress has been slow is the lack of funds as what has gone before has been strictly technology development on the basic systems of the SABRE. Next REL plans on building and running a full size SABRE engine to validate their simulation and models.

(Most of which are based on well documented studies and research done since the mid-50s on similar engines cycles though none used the exact set up that REL has pioneered. I'm sad to say that a majority of the work was done in the United States and "abandoned" after the research was side-tracked into SCramjet research based on the false idea that SCramjets were both "required" and the ultimate "air-breathing" acceleration engine. Despite almost 50 years of focused research the SCramjet has yet to live up to even a third of its supposed "potential" and is far less closer to operational use than the SABRE is. They have so dominated the thinking that almost every "air-breathing" space launch concept MUST have them "tacked-on" at some point despite their lack of use in the majority of cases. Worse of course from my "pro-US" perspective is the fact that OUR engineers missed such a fundamental design flaw in their early Rocket-Based-Combined Cycle engine work in that they made a false assumption that "air-fed" rockets required the liqufication of the air prior to injection into the rocket motor. As just about anyone working on the LH2/LOX RL10 could have told them, a rocket greatly benefits from GAS injection of both the hydrogen AND the oxygen rather than liquid! Kudo's to REL but I'm still upset that the US HAD everything up to including an almost flight-weight engine ready for flight testing but circumstances didn't allow it :(  )

I suspect that once the full size SABRE is tested a lot more interest and money will be generated.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: banjo on 02/20/2015 06:08 pm
i don't understand the animosity toward REL.  what have they done to offend so?  to me REL brings to mind two things -  the sentiment behind the quote “We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard."   and  Concorde.

REL are working really hard on a disruptive idea that they had; one that they think can achieve the same as elon musk's goal of cheap rapid access to space for the benefit of mankind. good for them. that should inspire, not generate a load of naysaying.  what's wrong with you people?

when the space shuttle idea was proffered, did people say 'what's wrong with normal rockets?, we know how to do normal rockets'  were there naysayers arguing for incremental steps?  i don't know.  the result was awesome.   

' what's wrong with normal aeroplanes?'   and then out rolls concorde.  if there were people at the time who tried to undermine the spirit of the project,  i bet they were as awestruck as the rest of us when the result took off in front of them.

the world has been mesmerised by  spacex landing rockets and capsules; by them constructing a BFR,  and then out rolls Skylon sounding like the end of the world.   how is this bad?  if it is difficult, if it takes a long time, are they reasons for REL to give up?  of course not.  the world needs passionate and competent innovators of their ilk.  they should be encouraged.  i wonder if this thread is getting REL down. i hope not.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Lars-J on 02/20/2015 06:22 pm
i don't understand the animosity toward REL.  what have they done to offend so?  to me REL brings to mind two things -  the sentiment behind the quote “We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard."   and  Concorde.

REL are working really hard on a disruptive idea that they had; one that they think can achieve the same as elon musk's goal of cheap rapid access to space for the benefit of mankind. good for them. that should inspire, not generate a load of naysaying.  what's wrong with you people?

Speaking for myself only, here - I have no animosity towards REL. Zero. I really do hope they succeed.

What does rub me the wrong way, however, is how the two main "Skylon evangelists" on this forum (not affiliated with REL but happy to speak on their behalf it seems)  ::) portray Skylon as a "done deal". Discussing it as of it already exists. Denigrating the hard work by done by people trying for the same goal but by different means.

There is also an element of "been there, seen that" skepticism. Skylon is just another in the long line of SSTO-ish launch concepts that were at their own time portrayed as the greatest idea since sliced bread. So some skepticism is warranted, and this is why I post - to counter the outlandish statements made quite frequently. If that is something "wrong with me", then so be it.

Does that make sense?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Impaler on 02/20/2015 06:35 pm
Siting the Space-shuttle and the Concorde as great beacons of success in this area gives me shudders down my spine.  These two vehicles are emblematic of why the criticism and doubt area valid, the Shuttle was expensive and dangerous, the Concorde could barely close it's business case in a much more established passenger service market.

And in response to JS19, if you want to count the detractors count me too, so were at 3 people now.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 02/20/2015 06:36 pm
But "my" point still stands that by the criteria Chris used, SpaceX was an "unproven" company despite all their "incremental" testing until they actually flew a successful, full-up flight :)

Yes, I agree, SpaceX was at one time an unproven company.  If we were back at the time before SpaceX had built and tested its first engine and SpaceX were making projections about how many cycles their reusable first-stage airframe could handle, I would say they didn't have enough information to be making projections like that and that such projections shouldn't be considered reliable.  In fact, back then SpaceX thought that they would be reusing their first stages by putting parachutes on them, covering them with cork, and fishing them out of the sea.  They even made their first engines salt-water-tolerant because of that plan.  And that's exactly my point -- a company that has yet to build its first engine has a lot of unknowns in front of it.

SpaceX took a much more incremental approach, and that allowed them to learn lessons and modify their approach.  Their approach was also much less of a leap beyond the existing state of the art at the time.  That allowed them to deal with all those unknowns.  What worries me about REL is that they seem to think they know most of the unknowns already, when I don't think they -- or anyone else -- possibly could.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 02/20/2015 06:50 pm
Denigrating the hard work by done by people trying for the same goal but by different means.

If by the "same goal" you mean fully-reusable, wasn't this JS19's point; to compare SABRE/Skylon with others also aiming for fully-reusable vehicles (with ELV-like payload fraction). I follow every post on this thread (5-off), and have seen little (if any) denigration of others' hard work.

Edit: Substituted "fully-reusable" for "SSTO"
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 02/20/2015 06:55 pm
i don't understand the animosity toward REL.

I haven't seen any evidence of animosity toward REL.  None.  I specifically said I hope they do succeed.

Skepticism is not the same as animosity.

The only animosity I've seen is between posters on this forum.

Skepticism is healthy.  People should welcome it even if they disagree.  Skepticism helps make sure the right decisions are made and makes it more likely we move forward in spaceflight, just like we all want.

what have they done to offend so?

Nothing at all.  Why do you interpret skepticism as offense?

to me REL brings to mind two things -  the sentiment behind the quote “We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard."   and  Concorde.

The worry is in fact that REL will turn into another Concorde -- a waste of money and talent on a system that was not economically viable.

If you visit the Hiller Aviation Museum in San Carlos, California, you can see a large section of the front of what looks a lot like Concorde.  It was actually built by Boeing, at the same time Concorde was under development.  The Boeing program was going well and they could have completed their own supersonic airliner.  But they cancelled the project because they judged it wouldn't be economically feasible.  Boeing was right.  By cancelling that project, they freed up resources and engineering talent for other projects that benefited the aerospace industry.

If you read my earlier post carefully, you would realize I wasn't calling for the cancellation of the technology REL is trying to develop.  I was instead suggesting more caution in projections and a more flexible, incremental development approach.

REL are working really hard on a disruptive idea that they had; one that they think can achieve the same as elon musk's goal of cheap rapid access to space for the benefit of mankind. good for them. that should inspire, not generate a load of naysaying.  what's wrong with you people?

I find it very sad that you interpret well-intentioned skepticism as being a character flaw.  Even if you disagree with our skepticism, why can't you accept that it comes from good intentions?

when the space shuttle idea was proffered, did people say 'what's wrong with normal rockets?, we know how to do normal rockets'  were there naysayers arguing for incremental steps?  i don't know.  the result was awesome.   

A discussion of the Space Shuttle is off topic for this thread, but suffice it to say there are many people who think the Space Shuttle program was a mistake and a more incremental approach that didn't try to do so much would have been a better use of resources.  Many people think the space shuttle kept of stuck in Low Earth Orbit for decades when we could have been exploring far beyond.

' what's wrong with normal aeroplanes?'   and then out rolls concorde.  if there were people at the time who tried to undermine the spirit of the project,  i bet they were as awestruck as the rest of us when the result took off in front of them.

the world has been mesmerised by  spacex landing rockets and capsules; by them constructing a BFR,  and then out rolls Skylon sounding like the end of the world.   how is this bad?  if it is difficult, if it takes a long time, are they reasons for REL to give up?  of course not.  the world needs passionate and competent innovators of their ilk.  they should be encouraged.  i wonder if this thread is getting REL down. i hope not.

Blind encouragement and ignoring potential mistakes is ultimately bad for any project.  True friends are honest, even if they have to say things people don't want to hear.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 02/20/2015 06:57 pm
LarsJ, Do I then assume that you deride the various "Fully-reusable TSTO is a done deal" SpaceX fans the same way? :)

No Skylon is FAR from a "done-deal" but it does have many features and abilities that are inherent to its nature if it works even remotely close to what its supposed to. I am as hopeful as you are that it works but well aware of the numerous "risks" still to be retired. On the other hand I'm also a SpaceX supporter though I will admit (as many won't) the various and sundry short-comings inherent in the design and principles of that vehicle/design.

"Comparing" the two is frustratingly common and misleading as I've pointed out before.

Skepticism is to be expected for it can be overcome with education and data. (Not to mention working hardware :) ) And yes Skylon is the latest in a long line of "promising" SSTO vehicle but I'd point out that it in fact is much close to, and much easier to implement than most where and does not (at this point) really need as significant technologies as most of the previous concepts did. The two biggest hurdles technology wise were the heat exchanger and the rocket motor both of which have been demonstrated. A full size working engine is next and really that's simply engineering the various components together and there's quite a bit of "prior-history" for that.

Impaler, not sure if you really want to be labeled as a 'detractor' as most here who actively engage in it have to rely on arguing the business case rather than technical details :) I'll admit to some trepidation on the assumptions involved but they DO actually have a historic (aircraft) model to draw on. Doubts are common and normally a good thing as long as they are not carried too far :)

I understand that many folks have differing ideas on how REL "should" proceed from this point but really a full size engine IS the next step. After that...

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Kansan52 on 02/20/2015 06:59 pm
Thanks Randy. That summary really helps me!!
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 02/20/2015 07:08 pm
Yes, I agree, SpaceX was at one time an unproven company.  If we were back at the time before SpaceX had built and tested its first engine and SpaceX were making projections about how many cycles their reusable first-stage airframe could handle, I would say they didn't have enough information to be making projections like that and that such projections shouldn't be considered reliable.  In fact, back then SpaceX thought that they would be reusing their first stages by putting parachutes on them, covering them with cork, and fishing them out of the sea.  They even made their first engines salt-water-tolerant because of that plan.  And that's exactly my point -- a company that has yet to build its first engine has a lot of unknowns in front of it.

I'm going to point out that the bolded part is NOW not "back-then" as SpaceX does NOT have the data to make accurate predictions... yet.

Yes REL faces a lot of "unknowns" in assembly of their first engine but the basic technology and techniques are already in place. They have already retired two of the biggest with the heat exchanger and rocket. Their biggest hurdle continues to be money, not competence or capability. Where would SpaceX be without Musk and his money?

Quote
SpaceX took a much more incremental approach, and that allowed them to learn lessons and modify their approach.  Their approach was also much less of a leap beyond the existing state of the art at the time.  That allowed them to deal with all those unknowns.  What worries me about REL is that they seem to think they know most of the unknowns already, when I don't think they -- or anyone else -- possibly could.

Which unknowns would those be? I'm curious.

SpaceX's approach was highly conservative in most respects. They built an ELV with the idea of eventually turning it into an RLV. They then rebuilt it as an RLV but still usable as an ELV. In the end its going to remain an RLV that "can" be an ELV and in that sense its limited (and they admit this) and eventually will end up a "dead-end" no matter how successful. But it's a start and in the right direction so kudos and I'm rooting for them.

REL is aiming for a different vehicle, operational mode, and model from the start and they have far less resources than SpaceX did to do it with. That in no way makes one approach "better" than the other.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 02/20/2015 07:23 pm
Yes, I agree, SpaceX was at one time an unproven company.  If we were back at the time before SpaceX had built and tested its first engine and SpaceX were making projections about how many cycles their reusable first-stage airframe could handle, I would say they didn't have enough information to be making projections like that and that such projections shouldn't be considered reliable.  In fact, back then SpaceX thought that they would be reusing their first stages by putting parachutes on them, covering them with cork, and fishing them out of the sea.  They even made their first engines salt-water-tolerant because of that plan.  And that's exactly my point -- a company that has yet to build its first engine has a lot of unknowns in front of it.

I'm going to point out that the bolded part is NOW not "back-then" as SpaceX does NOT have the data to make accurate predictions... yet.

Yes, they don't have the data to be fully confident.  It's still somewhat uncertain.  But having actually designed, built and flown real stages, done water landings, flown Grasshopper and F9R-dev1 in Texas, they do have some data to go on.  They have done enough to be far, far more confident about how many times they can re-use it than REL.

Yes REL faces a lot of "unknowns" in assembly of their first engine but the basic technology and techniques are already in place. They have already retired two of the biggest with the heat exchanger and rocket. Their biggest hurdle continues to be money, not competence or capability. Where would SpaceX be without Musk and his money?

True, Musk was an asset to SpaceX without a doubt.  But he had $100 million to invest.  REL says they need more than 100 times that amount of money.

REL needs both investors and a cheaper program to have a better shot at actually succeeding.

Quote
SpaceX took a much more incremental approach, and that allowed them to learn lessons and modify their approach.  Their approach was also much less of a leap beyond the existing state of the art at the time.  That allowed them to deal with all those unknowns.  What worries me about REL is that they seem to think they know most of the unknowns already, when I don't think they -- or anyone else -- possibly could.

Which unknowns would those be? I'm curious.

They are all the things that aren't anticipated in advance that are learned when doing the detailed design and when doing flight tests of that design.

SpaceX's approach was highly conservative in most respects. They built an ELV with the idea of eventually turning it into an RLV. They then rebuilt it as an RLV but still usable as an ELV. In the end its going to remain an RLV that "can" be an ELV and in that sense its limited (and they admit this) and eventually will end up a "dead-end" no matter how successful.

Huh?  That makes no sense to me.  Because it can be used as either an expendable or reusable vehicle it's a dead end?  Just because it can be used as expendable doesn't mean it's any less effective as a reusable vehicle.

But it's a start and in the right direction so kudos and I'm rooting for them.

REL is aiming for a different vehicle, operational mode, and model from the start and they have far less resources than SpaceX did to do it with. That in no way makes one approach "better" than the other.

The SpaceX approach has so far succeeded.  Past programs that were more like the REL approach have failed.  That's what makes one approach better than the other.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 02/20/2015 07:53 pm
I haven't seen any evidence of animosity toward REL.  None.  I specifically said I hope they do succeed.

I don't think it's YOU that's being referred to :) I seem to recall at least one post where REL was called an outright 'fraud' which I think would be considered "animosity".

Quote
Skepticism is not the same as animosity.
Skepticism is healthy.  People should welcome it even if they disagree.  Skepticism helps make sure the right decisions are made and makes it more likely we move forward in spaceflight, just like we all want.

No it's not and in measure its a good thing. However, skepticism focused on "second-guessing" someone who's actually "done-the-math" and bent metal in testing is another level. (One I'm guilty of with SpaceX at times I must admit :) )

And how 'helpful' is skepticism when it is mis-directed and/or non-constructive? Not that it probably actually matters since we're on these forums and both SpaceX and REL would seem to read but not take our "opinions" into their consideration :)
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The worry is in fact that REL will turn into another Concorde -- a waste of money and talent on a system that was not economically viable.

And it's from this "point-of-view" that your argument make no sense :) REL is not Boeing (your example) and if Boeing DOES come on-board at some point they will have made the exact calculations and studies you mention. You seem to assume that "someone" is going to blindly accept REL's figures which hasn't been done by anyone so far as evidenced by the "lack" of investors beating down their door. The "talent and money" they are using is the same ones they started out with and they DON'T have "other" business that they are taking these from. So your 'fear' would seem groundless which makes me suspect its NOT what your really questioning :)
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If you read my earlier post carefully, you would realize I wasn't calling for the cancellation of the technology REL is trying to develop.  I was instead suggesting more caution in projections and a more flexible, incremental development approach.

Got that but you don't seem to understand the limitations on REL due to the technology involved. They ARE being incremental. Unless the SABRE under-performs by a very significant margin their work shows that going with a TSTO design WOULD be un-economical (which is supposedly an underlying concern of yours) compared to a fully SSTO design. If this is "true" then they will find out with the full-up engine demonstrator and thereby adjust their development plans accordingly. (Considering that Mardquart had an Mach-4.5 "almost-flight-weight" LH2/LOX capable RBCC-SERJ engine ready for testing in the early 1960s WITHOUT deep-cooling or an air-fed rocket motor I consider this an unlikely complication)

Again, your "skepticism" seems misdirected.

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I find it very sad that you interpret well-intentioned skepticism as being a character flaw.  Even if you disagree with our skepticism, why can't you accept that it comes from good intentions?

"I" don't consider it a character flaw BTW so we're clear :) But I DO have to wonder at the "intentions" given the circumstances. "Supporters" are being accused of "blind encouragement," "ignoring problems," and "Skylon evangelism" despite real attempts to answer and address questions and skepticism about the concept. Is it perhaps that BOTH sides are missing the point that the discussion comes from "good intentions" on both sides?

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A discussion of the Space Shuttle is off topic for this thread, but suffice it to say there are many people who think the Space Shuttle program was a mistake and a more incremental approach that didn't try to do so much would have been a better use of resources.  Many people think the space shuttle kept of stuck in Low Earth Orbit for decades when we could have been exploring far beyond.

Point here is that the "Space Shuttle" for good or ill IS the only current example of an operational RLV and therefore the "comparisons" no matter how inaccurate are inevitable as well :) Just like comparisons to the F9 seem to be despite the lack of "common-ground" for such :)

(And anyone who even THINKS that it was the Shuttles "fault" we've been stuck in LEO for the last 40+ years is simply looking for an excuse to ignore the real reasons and why those reasons will continue to manifest themselves as long as the "government" is the driving factor)

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Blind encouragement and ignoring potential mistakes is ultimately bad for any project.  True friends are honest, even if they have to say things people don't want to hear.

Yep :) Shall we proceed from that point and continue the discussion friend? :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SteveKelsey on 02/20/2015 08:01 pm
Maybe it helps to bring it down to the differentiator. REL have delivered a pre-cooler that can enable a new air-fuelled rocket engine. This is a matter of fact, not opinion. The SABRE offers margins that are robust enough to enable reusable SSTO to be considered.
I don't think anyone is suggesting that the pre-cooler is anything other than a breakthrough.
From this breakthrough REL have projected what they believe they can deliver with the technology. There will be many other applications that are easier to deliver than an SSTO but that’s the deliver REL want to make.
Its entirely reasonable to point out that REL have a long way to go, and that the design will mature as learning progresses but just maybe the projections for and against have become a little ....searches for suitably diplomatic term...abstract?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Lars-J on 02/20/2015 08:15 pm

The two biggest hurdles technology wise were the heat exchanger and the rocket motor both of which have been demonstrated.

The rest of your post was reasonable, but this I must inquire about:
When was the rocket motor demonstrated? Did I miss that?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 02/20/2015 08:24 pm
I haven't seen any evidence of animosity toward REL.  None.  I specifically said I hope they do succeed.

I don't think it's YOU that's being referred to :) I seem to recall at least one post where REL was called an outright 'fraud' which I think would be considered "animosity".

Agreed.  I've never gotten the impression REL is a fraud.  On the contrary, I think the people there are very dedicated to their vision and have chosen to work on it for many years on lean funding in spite of the fact I'm sure they could find more lucrative things to do.

Is it perhaps that BOTH sides are missing the point that the discussion comes from "good intentions" on both sides?

That's a good point.  I think it always helps to assume that even those we disagree with have good intentions.

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Blind encouragement and ignoring potential mistakes is ultimately bad for any project.  True friends are honest, even if they have to say things people don't want to hear.

Yep :) Shall we proceed from that point and continue the discussion friend? :)

Yes! :-)  Skepticism of my skepticism is fair.

I think this particular discussion has more or less run its course.  We've all made our points, and other readers can judge for themselves what they find most persuasive.

I look forward to hearing more news from REL in the future so we have new things to discuss.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 02/20/2015 08:53 pm

The two biggest hurdles technology wise were the heat exchanger and the rocket motor both of which have been demonstrated.

The rest of your post was reasonable, but this I must inquire about:
When was the rocket motor demonstrated? Did I miss that?

It appears so; there have been a number of nozzle and flow demonstrator engines built and tested by REL and their associates:

STRICT
STERN
STRIDENT
STOIC
STILETTO

http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=33648.0;attach=571189
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 02/20/2015 09:35 pm

The two biggest hurdles technology wise were the heat exchanger and the rocket motor both of which have been demonstrated.

The rest of your post was reasonable, but this I must inquire about:
When was the rocket motor demonstrated? Did I miss that?

It appears so; there have been a number of nozzle and flow demonstrator engines built and tested by REL and their associates:

STRICT
STERN
STRIDENT
STOIC
STILETTO

http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=33648.0;attach=571189

Yes, those are important pieces of hardware being tested.  I think it's fairer to call them engine component tests rather than engines, though.  None is something you could put on a vehicle and have it fly.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 02/20/2015 10:48 pm
What would people think of separating this thread into two threads: Skylon Updates and Skylon Discussion?  There's been a lot of discussion in the Skylon threads, and not everyone who is interested in hearing about news from Skylon has the time or inclination to follow all the discussion.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 02/20/2015 11:12 pm
Just to say Richard Varvil has 2 Lectures coming up:

Tuesday, 14 April Skylon and Sabre - Bringing Space Down to Earth
http://aerosociety.com/Events/Event-List/1934/&

and

Thursday, 21 May The Skylon Spaceplane and Sabre Engine:- progress to date and future prospects’
http://aerosociety.com/Events/Event-List/1640/&

for anyone able to go.

Also on  the 26th of March he's a speaker at this event:

http://www.develop3dlive.com/speakers/

Finally  Alan Bond has a lecture here:
http://www.theiet.org/events/2015/210323.cfm?nxtid=

On the 4th of June called The SKYLON - the future of space transportation
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 02/20/2015 11:53 pm
I'm interested in what happens assuming they get things mostly right or what they might do if this or that issue turns out to be more difficult  because the alternative is that they go bust and the world is the same as before which is a non-story - why discuss it?
Indeed. Who'd start up a start up expecting to fail?
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We might as well mention that lots of people have built rockets before but this heat exchanger is exceptional so it speaks for their ability to come up with something unheard of and get it done right.
Yes, that's why they built it first.  If they couldn't make this work there was no point in continuing.

The key point is not only that it works but it works as designed which implies they have a deep understanding of how it works.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 02/20/2015 11:54 pm
The DC-X clearly meets your original point which had no requirement of being in charge or the end system becoming operational. Other projects that meet that criteria plus your newly added one of operational status are the EJ200, Spey and RB211 which Richard Varvill and John Scott Scott worked on, respectively.
For those who don't know these are low and high bypass ratio turbofan engines. The EJ200 powers the Eurofighter Typhoon and is therefor SoA for high T/W ratio engines running over a broad range of thrust and altitude settings.
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When are you proposing to stage this notional TSTO? Inside the atmosphere so you can use a simpler non rocket mode SABRE losing LOX tanks from the first stage or outside still using SABRE?
 Are you carrying the second stage internally or externally? If externally how are managing the damage that does to the aerodynamics and thermal protection? If internal how are making the vehicle trimable given the damage that does?   
What engine is powering the second stage?
How does any of that make the development of SABRE cheaper? Either you're proposing using the SABRE design as is, or you're suggesting development of a second engine, on top of SABRE, without a pure rocket mode neither of which can be cheaper for REL as an engine developer than just building SABRE.
Indeed. It's one of those ideas that sounds very sensible, until you look at it a bit more closely.
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I can't help feel that rocketry (successfully putting things in orbit since 1957)  is somewhat better understood that Scramjets ( someday soon we'll reach ten minutes cumulative flight time). Who is seriously researching scramjets for anything other than hypersonic cruise? Also please name these other people who think that the development challenges of NASP in 1984 are of comparable difficulty to the challenges of Skylon in 2015.
That would be an interesting list.
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Many people believe that VentureStar wasn't viable, but I don't think anybody believes the X-33 couldn't have flown and gathered useful data. The X-33 wasn't VentureStar, VentureStar was a powerpoint, X-33 was an active x-plane project with a similar budget and goals to the X-15. The X-15 wasn't a failure because it had no follow on project so why  should the X-33? When the X-15 first flew it didn't have it's intended engine yet because it wasn't ready, so why should the X-33 not have been given the same leeway? Like I said, there was a change in administration, a desire to cancel and repudiate the projects of the previous one, people obliged.
Actually the view amongst some people was that the X33 was extremely complex and risky for its stated purpose. I'd suggest VTOHL SSTO is the most difficult way to do it. It calls for both a T/W of at least 1.1:1 and a strong structure in two axes.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 02/20/2015 11:55 pm
EDIT: To offer a more substantive response. I don't think the line between science and engineering exists as you think it does. And what scientific breakthroughs have REL done? Their pre-cooler work would be classified by most as an impressive piece of engineering.
Well for those who are having a little trouble understanding the difference.
If you can look up the numbers or the models in a text book or report (and they produce accurate results IE within an acceptable limit of error) that's Engineering.

When you can't, because either the models are wrong or they simply don't exist then you're doing Science.

REL have practiced Science making the frost control system work. The bulk of the rest is expected to be Engineering.

SpaceX built a TSTO ELV. That's Engineering. 11 years in they have now have to do Science to learn
a)Landing high aspect ratio "floppy" structures b)Rocket ignition in a supersonic flow c) Aerodynamics and control over a wide Mach range using grid fins d) Modelling fluid slosh forces on pairs of very large tanks.

Somewhere along the way they've also discovered that their 2nd plan to do 2nd stage recovery can't be made to work without an unacceptable payload loss, which would indicate some (all ?) of their models were in error.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Impaler on 02/21/2015 12:22 am
What your calling Science I would simply call 'real man's engineering' and looking something up from a book is 'engineering for dummies'.  Iteration in engineering doesn't in my opinion make it a science because science is the creation and testing of theories, engineering is the creation and testing of devices.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: topsphere on 02/21/2015 12:56 am


Also on  the 26th of March he's a speaker at this event:

http://www.develop3dlive.com/speakers/


This is held at my University. I'll try and go - thanks for the heads up!!
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 02/21/2015 04:33 am

The two biggest hurdles technology wise were the heat exchanger and the rocket motor both of which have been demonstrated.

The rest of your post was reasonable, but this I must inquire about:
When was the rocket motor demonstrated? Did I miss that?

LOX apparently not air. So that's still a bit of question I suppose though to be honest the "Low-NOx" engine test would seem to indicate air use.
http://www.reactionengines.co.uk/sabre_techdevel.html

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 02/21/2015 04:38 am

The two biggest hurdles technology wise were the heat exchanger and the rocket motor both of which have been demonstrated.

The rest of your post was reasonable, but this I must inquire about:
When was the rocket motor demonstrated? Did I miss that?

LOX apparently not air. So that's still a bit of question I suppose though to be honest the "Low-NOx" engine test would seem to indicate air use.
http://www.reactionengines.co.uk/sabre_techdevel.html

On the page you link to, REL says this about the Low Nox test: "REL has designed and tested a new rocket combustion chamber".  A combustion chamber is an important part of a rocket motor, but it is only a part, not a complete motor.

It's also not clear whether this combustion chamber is full size or a small-scale test.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 02/21/2015 06:29 am
When are you proposing to stage this notional TSTO? Inside the atmosphere so you can use a simpler non rocket mode SABRE losing LOX tanks from the first stage or outside still using SABRE?
Are you carrying the second stage internally or externally? If externally how are managing the damage that does to the aerodynamics and thermal protection? If internal how are making the vehicle trimable given the damage that does?   
What engine is powering the second stage?
How does any of that make the development of SABRE cheaper? Either you're proposing using the SABRE design as is, or you're suggesting development of a second engine, on top of SABRE, without a pure rocket mode neither of which can be cheaper for REL as an engine developer than just building SABRE.
Indeed. It's one of those ideas that sounds very sensible, until you look at it a bit more closely.

lkm: Good questions because it IS a "good-idea" depending on the answers. REL has already determined it is NOT a good answer for their purposes and having read their reasoning I'd have to agree. Since I'm currently arguing the "viability" of sub-orbital rendezvous and re-fueling I can't very well say I don't think it's possible :)
Quote

Quote
I can't help feel that rocketry (successfully putting things in orbit since 1957)  is somewhat better understood that Scramjets ( someday soon we'll reach ten minutes cumulative flight time). Who is seriously researching scramjets for anything other than hypersonic cruise? Also please name these other people who think that the development challenges of NASP in 1984 are of comparable difficulty to the challenges of Skylon in 2015.
That would be an interesting list.

lkm: A WHOLE lot better but really "beside-the-point" as the whole attraction of SCramjets is how fast they can go in theory rather than fact in the first place :) The answer to the second is no one as that's about its only use being considered. And lastly I blame confusion between what was "required" of NASP with many of the supposed issues with Skylon. Well that and confusion with issues with the X-33, DC-Y, Roton, etc, etc, etc :)
Quote
Quote
Many people believe that VentureStar wasn't viable, but I don't think anybody believes the X-33 couldn't have flown and gathered useful data. The X-33 wasn't VentureStar, VentureStar was a powerpoint, X-33 was an active x-plane project with a similar budget and goals to the X-15. The X-15 wasn't a failure because it had no follow on project so why  should the X-33? When the X-15 first flew it didn't have it's intended engine yet because it wasn't ready, so why should the X-33 not have been given the same leeway? Like I said, there was a change in administration, a desire to cancel and repudiate the projects of the previous one, people obliged.
Actually the view amongst some people was that the X33 was extremely complex and risky for its stated purpose. I'd suggest VTOHL SSTO is the most difficult way to do it. It calls for both a T/W of at least 1.1:1 and a strong structure in two axes.

lkm: I'd be one of the ones who would argue that no, the X-33 would in fact NOT have been useful since it could not in fact met its flight related goals. That was in fact a major issue with the program as LM kept dropping the "goals" because the design was incapable of meeting the original series. Couple that with the development issues and cost over-runs it was pretty inevitable IMHO. Even if there had been no change in the political landscape the problems with the X-33 program overall would have ended up the same. Similarly I was never convinced that the VentureStar was going to happen even IF the X-33 was able to fly. LM had to constantly "update" the design to take into account problems they were running into with the X-33 AND there were inherent issues with the design that LM really should have known about given their background. (Come on, the design could not in fact "fly" because it was too tail heavy and no one in an aircraft company figured this out till AFTER? :) )

Comparison of the X-33 to the X-15 isn't really applicable. The "X-33" was an "X" vehicle only due to it supposedly being a technology demonstrator/development program which in fact it didn't do. The X-15 on the other hand was a test aircraft along the line of progression to higher speeds and altitudes. I don't actually consider the X-33, (or X-34, X-37, etc) to be actual "X-Planes" but this is pretty much OT for this thread.

JS19: While technically accurate (VTHL design) we HAVE done this before and its a pretty straight forward engineering problem. Has issue but then again so will designing and building what amounts to a hypersonic zeppelin :)

Its always a plus if you can design a vehicle to only handle the "exact" loads it needs and not a bit more. (Henry Ford logic/economics at work :) However that "logic/economics" leads to surviving a crash only to be killed when the "minimum" roof of the car collapse on you :) ) And since every ounce counts/costs going into space...

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Dalhousie on 02/21/2015 06:33 am

The two biggest hurdles technology wise were the heat exchanger and the rocket motor both of which have been demonstrated.

The rest of your post was reasonable, but this I must inquire about:
When was the rocket motor demonstrated? Did I miss that?

LOX apparently not air. So that's still a bit of question I suppose though to be honest the "Low-NOx" engine test would seem to indicate air use.
http://www.reactionengines.co.uk/sabre_techdevel.html

Randy

That page list contra-rotating turbines, Sabre combustion chamber, Sabre nozzles, low NOx engines, and Sabre intakes, so REL have a lot more than "just" a "cooler".
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 02/21/2015 08:32 am
The X-33 wasn't VentureStar, VentureStar was a powerpoint, X-33 was an active x-plane project

But when someone makes a comment like that about the Skylon vehicle vs REL's actual development, they get their heads bitten off.

Aside: One of the reasons the X-33 failed was the belief by some senior people that saying "there's no showstoppers" meant that you could treat development as a fait accompli. Therefore... Well, I recall (no refs, sorry, it was awhile ago) a program manager testifying before Congress that the program would be "worthless" (I think he even used that word) if it didn't launch with every piece of technology on his wish-list (mainly the composite hydrogen tank). So when the development of key pieces of technology stalled, what outcome would you expect?

I similarly worry that REL's people are so fixed on their end goal that they can't see alternative approaches. A TSTO is dismissed because it isn't as "economical" as their SSTO... which they expect will cost $10b to develop...

(I worry the same thing about Musk. But his development philosophy results in useful, low cost vehicles at each stage, even if his end goal fails.)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 02/21/2015 08:41 am
What would people think of separating this thread into two threads: Skylon Updates and Skylon Discussion?  There's been a lot of discussion in the Skylon threads, and not everyone who is interested in hearing about news from Skylon has the time or inclination to follow all the discussion.

Agreed. But I'd suggest three.

- REL development news. Info only (Plus the usual RFI questions. "Does anyone know if..." "Are they going to...")

[edit: Ah, what the hell, Reaction Engines Ltd (REL) news and information (http://forum.nasaspaceflight.com/index.php?topic=36851.0) )

- Skylon general discussion. Everything else... except...

- Alternative uses of REL tech. A2/Scimitar discussion. General application to aviation. Alternative applications to spacecraft. Alternative paths to Skylon. (The discussion you were trying to start, which got bogged down in... {waves hand} ...this.)


when the space shuttle idea was proffered, did people say 'what's wrong with normal rockets?, we know how to do normal rockets'  were there naysayers arguing for incremental steps?

I would suspect there were a lot of "naysayers" and "skeptics" arguing for a more incremental development path. Not because they hated the idea, or wished ill upon it, but because the Shuttle required too many new technologies all to work exactly as predicted. Any problems would turn the Shuttle into a fragile expensive system which would fail in its goal of making access to space affordable and routine...

And I know in the '80s a lot of us space advocates used the lack of incremental development in the Shuttle program in the '70s as an example of "what not to do". And we despaired as program after program (Freedom, NASP, VentureStar, even Delta Clipper to a degree(*), and almost all of the big science missions) repeated the same mistake with the same or similar results. And now, of course, SLS and Orion doing the same thing. "They say the definition of madness is doing the same thing over and over and expecting a different result."

It's this pattern that we see being repeated in Skylon, and this outcome that I fear for REL.

(* While DC-X was a lovely cheap research program, next "step" was meant to be a full sized SSTO demonstrator, DC-Y. Ick.)

Do I then assume that you deride the various "Fully-reusable TSTO is a done deal" SpaceX fans the same way?

Yes. Often.

I also deride those who build a strawman out of a handful of the most naive enthusiasts into some general behaviour of "SpaceX Fans".

Quote
And yes Skylon is the latest in a long line of "promising" SSTO vehicle but I'd point out that it in fact is much close to, and much easier to implement than most where and does not (at this point) really need as significant technologies as most of the previous concepts did.

Out of curiosity, can you think of a single one of those previous designs whose advocates didn't say exactly the same thing about their design?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: banjo on 02/21/2015 09:42 am


And from what I saw over the last 25 years, that's part of the reason it's taken so long for Bond's ideas to receive backing. If you're an investor (or administrator) in aerospace/aviation and this comes across your desk; a report that's actually about some guy who thinks he's solved the pre-cooler icing problem, but if you saw a picture of Skylon and pages of detail on the vehicle, payloads and missions, would you even read the report? Would you wade through the rest to even get to the two paragraphs on Bond's actual pre-cooler design? Because Skylon hit the quadrella of aerospace "alarm bells": a tiny unknown company proposing a radical vehicle design, plus it's an SSTO, plus it uses air-breathing jet/rocket hybrid engines, plus it's all based (with no margins) around their own new unproven technology proposal.

OTOH, you're in aerospace and a report crosses your desk about a small start-up that thinks it has solved the pre-cooler icing program. They point out that if their idea works, it could make high-speed turbojet engines more efficient and effective. Oh sure, they speculate - just as an aside, making it clear that they are just speculating - that the idea could even be useful for future space vehicles. And that's it, the report is about their pre-cooler idea, nothing else.

that's some back to front thinking you have going on there Paul451.   REL need heavy investment.  Investors need to be wooed.  showing them what the ultimate goal of their investment is is logical.   telling them that you have done no work on plausible applications of the pre-cooler breakthrough and then asking for investment is nuts.   REL did exactly the right thing in commissioning business case reviews and framing end use scenarios.  if you're after investment, this is what you do.

about wooing investors with the promise of making high-speed turbojet engines more efficient and effective.  why would they?   REL's goal is not to make high-speed turbojet engines more efficient and effective.   we know what their ultimate goal is and they are entitled have it. 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 02/21/2015 09:56 am
Out of curiosity, can you think of a single one of those previous designs whose advocates didn't say exactly the same thing about their design?

SSTO was always about making up negative margins with handwavy breakthroughs.  X-33 was actually sold on that basis.  Before Skylon, what SSTO concept had double-digit mass margins after decades of iterative design and component fabrication/testing? What SSTO concept could have absorbed a 10% Isp hit (and used up its structural margins) without failing to make orbit?  REL has been busy making sure nothing on the vehicle is below TRL 4 before committing to so much as an engine development program, and while the resulting design is unconventional it does not seem to require any breakthroughs.

Paul451, I understand you haven't really been around for the technical discussions, but it gets really old having newcomers assume proponents of the idea are handwaving in a vacuum.  Skylon is nothing like X-30.

Lars_J, you have been around long enough and should know better.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 02/21/2015 10:27 am
that's some back to front thinking you have going on there Paul451.   REL need heavy investment.  Investors need to be wooed.  showing them what the ultimate goal of their investment is is logical.

And yet for over 20 years it didn't work. Only now are they picking up some actual revenue, and not for Skylon but for a hypersonic passenger plane study.

"Step 1: Get £10 billion investment..."

Umm, no.

Quote from: banjo
about wooing investors with the promise of making high-speed turbojet engines more efficient and effective.  why would they?

Because high speed military aircraft are a lucrative market. And a company that develops the next big thing in aircraft engines will end up with much spare cash for their more speculative R&D.

And I suspect they'll end up somewhere like that anyway. Only it will take a demonstration of the full SABRE engine to get potential customers to ignore Skylon long enough to say, "Oh hey, that's actually useful technology". Something REL may have achieved 15-20 years sooner had they not publicly fixated on Skylon.

Paul451, I understand you haven't really been around

I've just started posting here, but I've been watching REL since they started, and HOTOL before it. And I've been "around" these discussions long before NSF existed. Your patronising is unnecessary.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 02/21/2015 10:41 am
that's some back to front thinking you have going on there Paul451.   REL need heavy investment.  Investors need to be wooed.  showing them what the ultimate goal of their investment is is logical.

And yet for over 20 years it didn't work. Only now are they picking up some actual revenue, and not for Skylon but for a hypersonic passenger plane study.

I thought their money is from a 60 million pound government investment for developing SABRE and private capital.  I mean I know they were part of LAPCAT but that seems like a minor part of what funding they managed to get.  Why are you leaving out the major sources?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 02/21/2015 10:44 am
What your calling Science I would simply call 'real man's engineering' and looking something up from a book is 'engineering for dummies'.  Iteration in engineering doesn't in my opinion
make it a science because science is the creation and testing of theories, engineering is the creation and testing of devices.
Then you'll be pleased to know that SpaceX have been doing plenty of 'real man's engineering'   :)
 
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make it a science because science is the creation and testing of theories,
SpaceX's failure to deliver a fully reusable F9 strongly suggest that the current theories, and the models derived from them have flaws in them that mean going from their very public video to actual hardware was impossible.

That's when  you start doing Science.

BTW if you look at the book cases of successful real engineers in any field you'll find an extensive back catalogue of stuff they can dip into when a new problem arrives and say "Ah, this looks like something in <textbook name/journal article/web page I copied> " The skill is knowing how to "flex" what's there into what's wanted.

They are called "inspection" or "cookbook" methods but a lot of the time they get the job done.

Trouble is what SpaceX want to do is not in any "cookbook"  :(

That's when you start getting into Applied Physics and hacking the source code on your CFD systems.

Unfortunately that's when development schedules go out the window and you may have to scrap all your previous work. You think you can get away with something (turning an ELV into an RLV at a certain size while still having a large payload say) and you can't.

To make this more Skylon centric look at what Skylon does not do.  It does not
1) Take off vertically. So it's engine T/W  ratio can be worse and T/O Thrust much lower than GTOW. That's not the whole story of course. It's that it then turns the atmosphere around it into IIRC about 100 tonnes of extra propellant (80% of it is more strictly "reaction mass" but it all helps).

2) No main engine re ignition in an oncoming (albeit tenuous) hypersonic airstream.

3) No engines forward re-entry. I can't imagine the CFD days (weeks?)  SpaceX took for them to be comfortable doing that. In particular the heat load on the most forward bell of the most forward engine (it'll be slightly below the horizon of local airflow) That's a combined aero/thermo/chemical load simulation problem. It's like the little patch on the Apollo heat shield. The temperature fall off outside it is huge but that's because that patch will run hot

4) No direct exposure of main propellant tanks to airflow. This side steps heating and bending forces which will try the F9 1st stage to a "face on" directly into the flow have to be resisted. It also side steps questions about wheather the LOX vaporises and the Merlins need to run on GO2/RP1 instead.

5) No large lumps of propellants sloshing round in the main tanks, which are vented.  Keeping in mind an F9 stage is not "end on" to the stream so the deceleration forces smear the propellants onto the wall facing the airflow at an angle. Hard enough  (like a guy charging a door) to make the stage flips over? What's the safe loading range to avoid that? Is it enough to land on? Who knows.

6) No ablatives (of unknown erosion rates) to replace.

Some of these are Science problems with no existing methods to solve them and some of them are situations that have no precedence, so no one has got constants for them for others to use.

And those are the obvious ones from a layman's PoV.  :(

Those forces interact in lots of interesting ways to give new force vectors (which will of course change over the course of the flight).

SABRE/Skylon "solves" these problems by not having to deal with them. However it has a set of problems of its own to solve, which would be on topic for this thread. The difference is REL don't need flights to collect the basic data to start to build the models (not the vehicle, the models) in the first place.

So if you're a CFD programmer or an Applied Physicist this makes SpaceX possibly the most exciting place on the planet for you to work right now.  :)

And you will work.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 02/21/2015 11:53 am
I thought their money is from a 60 million pound government investment [...] Why are you leaving out the major sources?

Nothing sinister about it. It was an arbitrary decision to draw a distinction between the UK Govt giving them bare-minimum funding to keep REL viable, to keep from losing technology to someone else (even if they didn't believe in the technology enough to properly fund it), and someone completely independently saying "hey, you guys have mad skills, care to do some work for us?" The latter struck me as more significant, even if it garners fewer dollars pounds euros.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 02/21/2015 02:48 pm
that's some back to front thinking you have going on there Paul451.   REL need heavy investment.  Investors need to be wooed.  showing them what the ultimate goal of their investment is is logical.

And yet for over 20 years it didn't work. Only now are they picking up some actual revenue, and not for Skylon but for a hypersonic passenger plane study.

I thought their money is from a 60 million pound government investment [...] Why are you leaving out the major sources?

Nothing sinister about it. It was an arbitrary decision to draw a distinction between the UK Govt giving them bare-minimum funding to keep REL viable, to keep from losing technology to someone else (even if they didn't believe in the technology enough to properly fund it), and someone completely independently saying "hey, you guys have mad skills, care to do some work for us?" The latter struck me as more significant, even if it garners fewer dollars pounds euros.

I'm sorry but I read it as "they have no money other than for a hypersonic study" and I don't see how anyone could possibly read it otherwise.  Now it twists into another comment which is also wrong because they always have had private support and 60m pounds is the lesser part of it from what we know of their plans for developing the engine i.e. what they said they'd need versus what we know for sure they have.

Are we expected to have detailed information about their private funding? I didn't think private companies usually handed that kind of thing out to everyone.

It is obvious, however, that to get this far they certainly have impressed people who certainly have put a very large amount of money in.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Impaler on 02/21/2015 06:35 pm

SpaceX's failure to deliver a fully reusable F9 strongly suggest that the current theories, and the models derived from them have flaws in them that mean going from their very public video to actual hardware was impossible.

That's when  you start doing Science.

THIS is the kind of comment that destroys your credibility.   As Lars-J said earlier is smacks of "Denigrating the hard work by done by people trying for the same goal but by different means." 

It has been pointed out repeatedly to you that SpaceX is not PURSUING full reusability for F9 because they have decided to focus on the followup vehicle which they DO intend to make fully-reusable.  They have said this is a decision driven by market volume and development resource, NOT one forced on them by hitting technological barriers.

But you have been repeatedly portraying this a technical failure on SpaceX's part and further more that this failure invalidates the vertical take-off, vertical landing paradigm, leaving your preferred Horizontal arrangement the 'only' viable solution.  And you blatantly ignore that they are STILL WORKING on the goal, which puts them in the same race as REL, but miles ahead, while you try to treat them as if they have dropped out.

And no this is not Science, it is ALL engineering.  Science is creating the rocket-equation, Bernoulli's principle and all the other THEORIES that let us know how the world behaves.  SpaceX nor any other Airo-space company dose science, they engineer vehicles using well established theories.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 02/21/2015 06:48 pm
Thank you again, Impaler! Can I subscribe to your newsletter?
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 02/21/2015 08:39 pm

SpaceX's failure to deliver a fully reusable F9 strongly suggest that the current theories, and the models derived from them have flaws in them that mean going from their very public video to actual hardware was impossible.

That's when  you start doing Science.

THIS is the kind of comment that destroys your credibility.   As Lars-J said earlier is smacks of "Denigrating the hard work by done by people trying for the same goal but by different means." 

It has been pointed out repeatedly to you that SpaceX is not PURSUING full reusability for F9 because they have decided to focus on the followup vehicle which they DO intend to make fully-reusable.  They have said this is a decision driven by market volume and development resource, NOT one forced on them by hitting technological barriers.

But you have been repeatedly portraying this a technical failure on SpaceX's part and further more that this failure invalidates the vertical take-off, vertical landing paradigm, leaving your preferred Horizontal arrangement the 'only' viable solution.  And you blatantly ignore that they are STILL WORKING on the goal, which puts them in the same race as REL, but miles ahead, while you try to treat them as if they have dropped out.

And no this is not Science, it is ALL engineering.  Science is creating the rocket-equation, Bernoulli's principle and all the other THEORIES that let us know how the world behaves.  SpaceX nor any other Airo-space company dose science, they engineer vehicles using well established theories.

I kind of agree with what you said other than please do not just dismiss what REL has achieved so far by the glib sentence of saying that Space X is miles ahead. Especially as this is not some kind of race as I don't even regard Space X & REL as being in the same business.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 02/21/2015 08:43 pm
I kind of agree with what you said other than please do not just dismiss what REL has achieved so far by the glib sentence of saying that Space X is miles ahead.

To me, saying SpaceX is miles ahead doesn't dismiss what REL has achieved.  SpaceX was once far behind ULA, but held promise.  Being behind doesn't mean they won't eventually end up in front.  It just means they have a longer journey ahead and there is more uncertainty because of that.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 02/21/2015 09:16 pm
That's fine, but this engine company is making projections about the performance and economic viability of the complete system, including engines and airframe.

Don't they have to? Is it not necessary at all times to make such projections and keep updating them as new information is learned?

There'd be no shame in their saying "we don't know yet".

There no shame in that but say "we don't know yet", tend to put off investors and especially investors who will put money into such early projects, they want to be sold a dream a visions, they don't want ifs and buts.


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Personally I think the greatest threat to Skylon development will be a failure of an airframer to commit to it. I think REL may find that despite developing an engine that works well and engenders a lot of interest in the end there may be a general reticence to throw in with another companies grand scheme and disrupt their own planning among the likely consortium partners. I could see REL being bought by RR as a part of an attempt at forming a successful consortium only to end being used to get some lucrative US hypersonics research money.
This is my biggest fear as well, that REL squash under a barrage internal politics from any consortium.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Dalhousie on 02/21/2015 09:54 pm

SpaceX's failure to deliver a fully reusable F9 strongly suggest that the current theories, and the models derived from them have flaws in them that mean going from their very public video to actual hardware was impossible.

That's when  you start doing Science.

THIS is the kind of comment that destroys your credibility.   As Lars-J said earlier is smacks of "Denigrating the hard work by done by people trying for the same goal but by different means." 

It has been pointed out repeatedly to you that SpaceX is not PURSUING full reusability for F9 because they have decided to focus on the followup vehicle which they DO intend to make fully-reusable.  They have said this is a decision driven by market volume and development resource, NOT one forced on them by hitting technological barriers.

But you have been repeatedly portraying this a technical failure on SpaceX's part and further more that this failure invalidates the vertical take-off, vertical landing paradigm, leaving your preferred Horizontal arrangement the 'only' viable solution.  And you blatantly ignore that they are STILL WORKING on the goal, which puts them in the same race as REL, but miles ahead, while you try to treat them as if they have dropped out.

And no this is not Science, it is ALL engineering.  Science is creating the rocket-equation, Bernoulli's principle and all the other THEORIES that let us know how the world behaves.  SpaceX nor any other Airo-space company dose science, they engineer vehicles using well established theories.

I think you are completing misreading John Smith 19's points.  As I read it, he is pointing out that there is a difference between applying well known existing engineering principles to a particular problem (engineering), and developing new processes that require new and deeper understand of fundamental processes (science). The distinction isn't clear cut, but it is there.

Nor is it correct to say that John Smith 19 has consistently denigrated SpaceX.  He has not as far as I can see. He has merely pointed out that SpaceX and REL are approaching things differently and have different goals.  As others have said, it isn't a race.


Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 02/21/2015 10:43 pm
Question: Do we think we know enough about SABRE to state categorically that it only works when integrated with a Skylon type of airframe? Are there no other possibilities? Like, say, fitting it to a smaller vehicle that has aerodynamics/wing area suited for landing, but that's air-launched from the StratoLaunch carrier aircraft?

This is just a (probably crazy) example. If it could be useful in other configurations, what are they?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 02/21/2015 11:27 pm
"Step 1: Get £10 billion investment..."

Umm, no.

Background:  HOTOL was a high-resolution design study resulting in an airbreathing SSTO that looked marginally feasible but not economically interesting, powered by deeply precooled air turborocket engines (Rolls-Royce RB545) with a solution to the icing problem incorporated (no, it's not the same solution SABRE uses).  After the study was essentially completed and the involved parties lost interest, the engine tech got classified, with no indication (even now, after a quarter of a century) of any actual intent to use it.  So to circumvent the classified patents, Bond & co. came up with a modified engine cycle that actually turned out to be superior to the RB545.  They also rethought the airframe concept to eliminate one of the biggest problems with the original design.  It is at this point that REL was formed.

Step 1:  solicit small grants and investments and use them to buy down risk, partnering with industry and academia as appropriate.

Step 2:  land enough investment (millions) to carry out a comprehensive technology demonstration program with the goal of raising SABRE/Skylon's component TRL floor to 4, again seeking out external expertise as appropriate.  This program started in 2009, and one of the more prominent results was the flight-weight precooler hardware tested in 2012.
Step 2a:  simultaneous to Step 2, produce a high-fidelity vehicle design (Skylon D) to anchor the engine design, so as to avoid having to go back and redesign the engine once the vehicle takes shape.

Step 3:  leverage the results of the tech demonstration program to attract sufficient cash (hundreds of millions) to start intensive engine development.  This has apparently happened; the £60M government investment is not a keepalive fund but rather a pump primer for a large effort.  REL has been expanding significantly, and has apparently secured enough funding to forgo a subscale demonstrator (SCEPTRE) in favour of a full-size prototype SABRE.

Step 4:  With a full-size prototype SABRE showing good results on the test stand, get the interested parties to commit to full-scale vehicle development, which may well involve subscale and/or suborbital demonstrator vehicles.

At no point does REL itself ask anyone for a £10 billion investment.

...

As you can see, it is not accurate to claim REL is not doing "incremental development".  It just looks a bit different, because what they're trying to do is different.  It's not REL's fault there doesn't seem to be a commercially useful way to half-ass the idea (leaving aside peripheral stuff like the Valkyrie sounding rocket)...

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Because high speed military aircraft are a lucrative market. And a company that develops the next big thing in aircraft engines will end up with much spare cash for their more speculative R&D.

The precooler tech is tied to hydrogen fuel.  This immediately makes it useless on any existing airframe, creating a very high entry barrier, and greatly complicates the operation of any new vehicle using it.  The difficulties of hypersonic cruise only make this situation worse.  (Remember, existing engine tech is perfectly capable of propelling an aircraft faster than any currently-operational aircraft actually goes.)  Space launch is about the only market with a clear near-term use for the technology.

The U.S. military hates hydrogen, probably because logistics are so important to them.  They don't even like LOX.  I don't know why the USAF is interested in SABRE, but I'd be willing to bet it's not for a fighter.

Non-aerospace applications of the precooler technology are possible, but they will have to wait until the manufacturing process is refined and the price comes down...

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I've just started posting here, but I've been watching REL since they started, and HOTOL before it. And I've been "around" these discussions long before NSF existed.

Yet you don't seem to know much about it, and a lot of what you think you know seems to be wrong.

Science is creating the rocket-equation

No.  The rocket equation could be derived in short order by any reasonably competent engineer who actually bothered to think about the problem.  Tsiolkovsky was merely one of the first people to do so (not the very first; it shows up in earlier sources).  The "science" in the rocket equation is all Newton.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 02/21/2015 11:46 pm
I think USAF is interested in SABRE simply because they hate the thought of anyone else having something that outclass anything they are working on at least publicly.

 The last thing they want is the Chinese showing up in 20 years time having developed their own Sabre/Scimitar  engine powered aircraft either independently or stolen from REL and USAF not having any answers . This is good news for REL assuming they can figure out how to get hold of USAF money without to many strings being attach  ;).

Plus with hydrogen being use in cars and in buses and everyday civilian lives there probably some in USAF that thinks it time for their hatred of hydrogen fuel engines to come to an end. Especially as their scramjets projects seems to crash just as often as they manage to fly.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 02/21/2015 11:58 pm
Do we think we know enough about SABRE to state categorically that it only works when integrated with a Skylon type of airframe?

SABRE isn't tightly integrated with the airframe like a scramjet is.  All it strictly requires is a source of liquid hydrogen.

The only airframe-integration feature I can think of is the nacelle camber, which is due to the difference between the desired angle of attack and the desired angle of thrust.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Chris Bergin on 02/22/2015 01:30 am
Ok guys, this thread is a problem as not a day goes by without report to mods coming in, mainly due to off topic and a few people getting rowdy with each other.

All posts from this point onwards will be on topic and civil.

No excuses.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 02/22/2015 03:37 am
Do we think we know enough about SABRE to state categorically that it only works when integrated with a Skylon type of airframe?

SABRE isn't tightly integrated with the airframe like a scramjet is.  All it strictly requires is a source of liquid hydrogen.

The only airframe-integration feature I can think of is the nacelle camber, which is due to the difference between the desired angle of attack and the desired angle of thrust.

That's my understanding too. So what other airframe configurations might make sense? And are there any that are less ambitious/costly than the Skylon vehicle as currently conceived?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 02/22/2015 11:01 am
JS19: While technically accurate (VTHL design) we HAVE done this before and its a pretty straight forward engineering problem. Has issue but then again so will designing and building what amounts to a hypersonic zeppelin :)
True. But it never would have worked without those monster RATO packs and the humungous drop tank. :)
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Its always a plus if you can design a vehicle to only handle the "exact" loads it needs and not a bit more. (Henry Ford logic/economics at work :) However that "logic/economics" leads to surviving a crash only to be killed when the "minimum" roof of the car collapse on you :) ) And since every ounce counts/costs going into space...
Sometimes referred to as the "one horse shay" paradign.  :)

I think you are completing misreading John Smith 19's points.  As I read it, he is pointing out that there is a difference between applying well known existing engineering principles to a particular problem (engineering), and developing new processes that require new and deeper understand of fundamental processes (science). The distinction isn't clear cut, but it is there.

Nor is it correct to say that John Smith 19 has consistently denigrated SpaceX.  He has not as far as I can see. He has merely pointed out that SpaceX and REL are approaching things differently and have different goals.  As others have said, it isn't a race.
Your are correct in all points. There was much more I'd written, but it's OT and I'd like to bring it back to SABRE/Skylon.  :(

That's my understanding too. So what other airframe configurations might make sense? And are there any that are less ambitious/costly than the Skylon vehicle as currently conceived?
That's tricky without understanding why they developed this configuration.

The problem is twofold.

The Centre of Pressure shifts a lot over an airframe going from 0-M23-0

The Centre of Gravity shifts a lot because propellant is a much bigger fraction of the vehicle weight than in an aircraft.

A key  problem with HOTOL was with the engines at the back as the tanks emptied you had very little mass to stop the body "flipping" upward, so you needed a huge set of control surfaces (and their actuators) to keep the nose at the right angle. IIRC Bond said "2000 tonne metres" IE a small ship on those control surfaces.

Terrestrial aircraft can get away with the engines at the back (Trident DC-10, Caravelle) because of a) A relatively empty fuselage b) "Wet" wings and c) More "dead" weight in the vehicle to counter balance the weight of the engines in the back.

There are various configurations you could build a SABRE (ideally a pair of SABRES) into but they all face 2 problems.

High pressure LH2 engines (or rather their turbo pumps) scale down badly so you'd want to use full size SABRE engines.

It's not what your sub scale prototype can demonstrate it's what it cannot. Those things can only be demonstrated in the full size vehicle, IE a Skylon. So you're building a Skylon (actually REL are planning 2 flight test Skylons) and  this demonstrator/proof-of-concept/whatever vehicle, so your overall budget goes up.  :(

My instinct is the simplest way to go is with full size SABRES propelling a reduced scale Skylon airframe with narrower, shorter fuselage, no payload bay (and no payload  :( ) and much lower propellant load.

If such a vehicle matches a full sized Skylons aerodynamics and mass properties then its results should be transferable directly to the full size Skylon, shortening the flight programme of the full sized vehicles to lower the overall development budget and "squaring the circle" of using 3 vehicles instead of 2 but still working out cheaper.   :)

IRL my instinct is that being able to scale a design to that way while preserving all the main features is a very big "if" indeed. I suspect the range over which you could scale the airframe while a)Using full size SABRES and b)keeping the various mass properties and aerodynamic coefficients matching the full size vehicle is very limited.

The question is not "can you scale it down" but "do you save so much on the test budget it's worth doing" ?

I suspect the answer comes out "Build a full size Skylon with full size engines and no payload bay (there is room, but only enough is installed to preserve necessary structural stiffness) and smaller tanks," and I think REL have a better idea of the answer, but I don't know what it is.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 02/22/2015 08:15 pm
I suspect the answer comes out "Build a full size Skylon with full size engines and no payload bay (there is room, but only enough is installed to preserve necessary structural stiffness) and smaller tanks," and I think REL have a better idea of the answer, but I don't know what it is.  :(

Hmmm, you may be right. At first blush, building a half-scale Skylon seems less ambitious, and so more likely to happen, i.e. receive funding. Skylon as currently described is soooo huge that size alone makes the whole project appear impractical. BUT once you've committed to the design of a few square meters of aeroshell/tankage, then manufacturing lots and lots of square meters is not that much more difficult/costly than half as much. This is probably made easier because Skylon has such a regular/recurring shape.

And as you say, smaller and lighter internal tanks give you lots of margin to play with on the test vehicle, and lower loads... And unlike other spacecraft you have the option of loading a small amount of LH2 (and no O2) which again lowers weight and loads.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: space_britannia on 02/23/2015 11:36 pm

The U.S. military hates hydrogen, probably because logistics are so important to them.  They don't even like LOX.  I don't know why the USAF is interested in SABRE, but I'd be willing to bet it's not for a fighter.


I wouldn't be surprised if it's for SUSTAIN ("Marines in Space") - see http://www.popsci.com/military-aviation-space/article/2006-12/semper-fly-marines-space
http://www.popularmechanics.com/military/a5539/plans-for-marines-in-space/
http://www.defenseindustrydaily.com/hypersonic-rocketplane-program-inches-along-0194/

Those stories talk about a 2-stage concept however, and whether with scramjets or sabre (hydrogen fuel issue again), that's going to be one very expensive ride to ditch in the middle of a conflict zone
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Asteroza on 02/24/2015 02:35 am
Do we think we know enough about SABRE to state categorically that it only works when integrated with a Skylon type of airframe?

SABRE isn't tightly integrated with the airframe like a scramjet is.  All it strictly requires is a source of liquid hydrogen.

The only airframe-integration feature I can think of is the nacelle camber, which is due to the difference between the desired angle of attack and the desired angle of thrust.

That's my understanding too. So what other airframe configurations might make sense? And are there any that are less ambitious/costly than the Skylon vehicle as currently conceived?

Probably not , considering it's a tube with wings and you need spheres or tubes ideally for the tankage. Tube with wings is well known, and has low frontal area.

But, as a thought exercise, a squished pancake shape might work. Internally, you have three rows of cylindrical spaces, center with payload bay and fore/aft LOx tanks flanked by full length LH2 tanks. Fit the SABRE equipment near the mid-fuselage edge of the pancake, with a 2D ramp inlet on its side, and exhaust is half an aerospike ramp on its side. That largely preserves the basic Skylon layout (which does well to deal with cg changes), but frontal area drag unfortunately goes up which goes against the partial cruise accelerator profile. The only advantage to that layout is if you were doing something kinky like receiving external heating AKA Laser Skylon, as you could have a better receiver area.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 02/24/2015 03:50 am
I don't know why the USAF is interested in SABRE, but I'd be willing to bet it's not for a fighter.
I wouldn't be surprised if it's for SUSTAIN ("Marines in Space")

[Such speculation may be off-topic, I'm not sure how strictly to Skylon Chris wants the thread to run.]

There are other applications of the pre-cooler. Improving flight range via greater engine efficiency; higher speed from existing engines without overheating the engine; even reducing the IR signature of engine exhaust (which wasn't one I'd previously considered.) Plus you've got the ongoing interest in fast-turnaround small-sat launchers, a la DARPA XS-1.

(For other Services, you've got improved operations of any large turbine-based engine (increasingly common in non-nuclear ships.))
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 02/24/2015 06:15 am
The projected first flight of Skylon has always been far enough into the future, and the schedule burdened with sufficient unknowns that you can forgive critics for doubting it will ever see the light of day. But it occurred to me that if (big if) investors were to suddenly want to make it happen ASAP we could conceivably see it in the first half of the 2020s rather than the second for a couple of reasons.

Firstly, as REL have rightly pointed out before, the full engine cycle can be thoroughly tested on the ground. This is hugely beneficial, and additional cash would allow more extensive testing to be concluded sooner.

Secondly, the airframe could be prototyped/tested in parallel with the engine or beforehand. No-one's talks about doing this because if the SCEPTRE tests show major problems you won't need the airframe. However, if someone wanted to I suspect you could do subsonic testing of the airframe shape by placing turbojets in the nacelles. Perhaps you could then go supersonic by adding rockets and closing (and testing) the nacelles cones.

Don't ask me where the money and desire to do this will come from, but it's one more reminder that Skylon's problems have more to do with politics and economics than technology or necessarily long dev schedule.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 02/24/2015 09:09 am
I wouldn't be surprised if it's for SUSTAIN ("Marines in Space") - see http://www.popsci.com/military-aviation-space/article/2006-12/semper-fly-marines-space
http://www.popularmechanics.com/military/a5539/plans-for-marines-in-space/
http://www.defenseindustrydaily.com/hypersonic-rocketplane-program-inches-along-0194/

Those stories talk about a 2-stage concept however, and whether with scramjets or sabre (hydrogen fuel issue again), that's going to be one very expensive ride to ditch in the middle of a conflict zone
Welcome to the forum and the thread.

Firstly "Force projection" through space has a long history. Bono and Gatlands "Frontiers of Space" looked at delivering 100s of Marines at a time by "ballistic transport" IE near SSTO sub orbital vehicles. That was around 1969.

Reading the links you listed in detail they read like sales pitches for yet another SCRamjet research programme.  :(

AFAIK the CRADA is for SABRE engine cycle only. So the USAFRL can run the numbers (the pressures, temperatures and flows at various parts of the system) through their design codes and satisfy themselves that it it will produce the output they expect.

I do hope they pay attention to what the condition of the inlet air is as the Mojave desert is a little different from Kourou.  :)

It would seem that some in the USAF are starting to think the unthinkable.

"What if we do a vehicle without developing an SCRamjet in it as it does not need an SCRamjet?"

But Skylon is not designed as some kind of assault transport. The problem is you need to secure a landing strip before it arrives with reinforcements (although without LH2 and LO2 on board it can land on quite a poor runway), a chicken and egg situation.  :(

However "responsive" access to space IE launching payloads to monitor or assist in developing theaters of operations in days not years, has been an interest of some parts of the DoD for a long time, XS1 being the latest attempt (although that's gone rather quiet of late).

SABRE/Skylon can deliver such a capability.
BUT once you've committed to the design of a few square meters of aeroshell/tankage, then manufacturing lots and lots of square meters is not that much more difficult/costly than half as much. This is probably made easier because Skylon has such a regular/recurring shape.
Making things smaller in prototype has some history in aerospace to a point, but only to a point. This is why REL were looking for IIRC £250m then worked out that for £15m more they could a full size engine, so why not?

In mfg the hardware you have access to always has some limits on how big a thing you can make on it. For 1 offs you can probably find a way to exceed those limits (again, to a point ) but for repeat production you're looking at a step change in costs as now you've got to buy/build a whole new suite of machines to handle that.

NASA can do a 10m tank, but push it to 15m or 20m? I think you'd have to tear out the current hardware and replace it wholesale.  Obviously it's a question of what you're funded to and how far you think a concept can go when you're planning  your factory.
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And as you say, smaller and lighter internal tanks give you lots of margin to play with on the test vehicle, and lower loads... And unlike other spacecraft you have the option of loading a small amount of LH2 (and no O2) which again lowers weight and loads.
True.

It comes down to a very tricky problem. Can I find a cheaper way to do part of the programe (easing my fund raising problem) that does not mean I have to buy extra hardware (or tests) later, so increasing the overall cost, the problem I'm trying to avoid.

Probably not , considering it's a tube with wings and you need spheres or tubes ideally for the tankage. Tube with wings is well known, and has low frontal area.
Exactly.  Keep in mind that a "tube with wings" has already demonstrated successful reentry about 130 times
Quote
But, as a thought exercise, a squished pancake shape might work. Internally, you have three rows of cylindrical spaces, center with payload bay and fore/aft LOx tanks flanked by full length LH2 tanks. Fit the SABRE equipment near the mid-fuselage edge of the pancake, with a 2D ramp inlet on its side, and exhaust is half an aerospike ramp on its side. That largely preserves the basic Skylon layout (which does well to deal with cg changes), but frontal area drag unfortunately goes up which goes against the partial cruise accelerator profile. The only advantage to that layout is if you were doing something kinky like receiving external heating AKA Laser Skylon, as you could have a better receiver area.
If cost is the issue for a prototype you'd scrap the payload bay. This layout might handle the Cp/Cg shifts well enough to do the whole flight trajectory.

But look what you've lost  :(

This design is reminiscent of the "pye wacket" missile concept for an armed SR71 but AFAIK it has no flight history in other vehicles you can call on to refine the design.

Then you're suggesting some altitude compensation by expansion against the underside, which raises the temperature quite a bit.

And once you've got it working how do you translate the measurement of the flight programme to that of a Skylon?

It's a tough problem.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 02/24/2015 09:38 am
true that skylon could not land itself to deliver troops in a contested combat zone- it is also too expensive for this.

But may it could
1) deliver into space a specifically designed lander and its squad
2) deliver the specifically designed lander into space, and bring the squad there when it is needed.

in the option 1) it would work as a sort of first stage
in the option 2) it would work as a transport vehicle of its own. however I guess the timeframe for going to LEO, transit the squad in the vehicle stationning there,  and down again, isn't any close to "two hours". Although it would still solve the issue of transportation above unfriendly territory.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 02/24/2015 10:13 am
2) deliver the specifically designed lander into space, and bring the squad there when it is needed.

The lander-in-orbit would be limited to a single window in a single orbital plane, making it incompatible with the goal of a suborbital ballistic "drop-ship" to allow any point-to-point travel in 90 minutes or so.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 02/24/2015 03:38 pm
There are other applications of the pre-cooler. Improving flight range via greater engine efficiency; higher speed from existing engines without overheating the engine; even reducing the IR signature of engine exhaust (which wasn't one I'd previously considered.) Plus you've got the ongoing interest in fast-turnaround small-sat launchers, a la DARPA XS-1.

Just to note but these were "somewhat" brought up by REL as part of pushing the HE technology as a breakthrough "on-par" with the development of the jet engine itself and unfortunately isn't as "applicable" as REL made it out to be or having all that many "applications" above and beyond its actual use in SABRE.

Deep-Cooling can in fact extend the usable Mach range of a turbine based engine as well as increasing thrust output. But this was shown with previous work including the most recent Mass-Injection-Pre-Compressor-Cooling, and in fact does not require Liquid Hydrogen to accomplish things like a doubling of thrust and Mach number of the turbine engine. Increased engine efficiency is possible but only if the entire engine is run using hydrogen fuel as a standard hydrocarbon engine wouldn't stand to gain much due to the use of multiple fluids. (Which is already an "issue" with standard MIPCC which uses LOX/Water both of which are far more compact and easier to use than LH2)

"Standard" (LOX/Water) MIPCC can extend the Mach number of a standard (F100 for example) low-bypass turbofan from Mach-2 to Mach-4 and double or more the output thrust. Deep-Cooling with LH2 through an HE might extend this to Mach-6 though the extensive "bulk" of the LH2 tankage and system would probably greatly increase the vehicle design and complexity.

Exhaust IR mitigation IS a possible use but again mitigation doesn't "require" the use of liquid hydrogen and again unless the whole vehicle/engine is based on LH2 propulsion the use of an LH2 HE and bypass cooling air system wouldn't be very effective in operational use due to the added complexity and cost.

Last I looked the XS-1 program was specifically avoiding LH2 due to such systems NOT having fast turn around capability of more benign cryogenic systems such as LOX/Kero.

In most operational cases, unless your engine system and therefore your vehicle design overall, is using LH2 for fuel the efficiency isn't all that clear cut a case. Which is I suspect one of the (many) reasons no one is jumping on the REL investment bandwagon :)
What they are doing is directly relatable to GTO (Ground-To-Orbit) launch but doesn't have much broader uses under the current situation.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 02/24/2015 03:52 pm
I wouldn't be surprised if it's for SUSTAIN ("Marines in Space") - see http://www.popsci.com/military-aviation-space/article/2006-12/semper-fly-marines-space
http://www.popularmechanics.com/military/a5539/plans-for-marines-in-space/
http://www.defenseindustrydaily.com/hypersonic-rocketplane-program-inches-along-0194/

Those stories talk about a 2-stage concept however, and whether with scramjets or sabre (hydrogen fuel issue again), that's going to be one very expensive ride to ditch in the middle of a conflict zone
Welcome to the forum and the thread.

Firstly "Force projection" through space has a long history. Bono and Gatlands "Frontiers of Space" looked at delivering 100s of Marines at a time by "ballistic transport" IE near SSTO sub orbital vehicles. That was around 1969.

Earlier than that actually :)

@1958 the Army did some research on delivering troops and/or supplies to the front lines by sub-orbital ballistic missile delivery. Specifically the "Redstone" IRBM:
http://www.popsci.com/blog-network/vintage-space/riding-rocket-battlefield

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 02/24/2015 04:40 pm
2) deliver the specifically designed lander into space, and bring the squad there when it is needed.

The lander-in-orbit would be limited to a single window in a single orbital plane, making it incompatible with the goal of a suborbital ballistic "drop-ship" to allow any point-to-point travel in 90 minutes or so.

Just to make sure everyone's on the same page, the actual SUSTAIN/Hot Eagle requirements had the vehicle being capable of P2P travel OR being put into orbit as a "standby" measure for "drop" at any point up to several days later.

The conflicting requirements of those two mission parameters were something that was never addressed and would drive a "vehicle" design that would be very costly to meet both requirements.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 02/24/2015 06:49 pm
Do we think we know enough about SABRE to state categorically that it only works when integrated with a Skylon type of airframe?

SABRE isn't tightly integrated with the airframe like a scramjet is.  All it strictly requires is a source of liquid hydrogen.

The only airframe-integration feature I can think of is the nacelle camber, which is due to the difference between the desired angle of attack and the desired angle of thrust.

That's my understanding too. So what other airframe configurations might make sense? And are there any that are less ambitious/costly than the Skylon vehicle as currently conceived?

That's my understanding too. So what other airframe configurations might make sense? And are there any that are less ambitious/costly than the Skylon vehicle as currently conceived?
That's tricky without understanding why they developed this configuration.

The problem is twofold.

The Centre of Pressure shifts a lot over an airframe going from 0-M23-0

The Centre of Gravity shifts a lot because propellant is a much bigger fraction of the vehicle weight than in an aircraft.

A key  problem with HOTOL was with the engines at the back as the tanks emptied you had very little mass to stop the body "flipping" upward, so you needed a huge set of control surfaces (and their actuators) to keep the nose at the right angle. IIRC Bond said "2000 tonne metres" IE a small ship on those control surfaces.

Terrestrial aircraft can get away with the engines at the back (Trident DC-10, Caravelle) because of a) A relatively empty fuselage b) "Wet" wings and c) More "dead" weight in the vehicle to counter balance the weight of the engines in the back.

There are various configurations you could build a SABRE (ideally a pair of SABRES) into but they all face 2 problems.

High pressure LH2 engines (or rather their turbo pumps) scale down badly so you'd want to use full size SABRE engines.

It's not what your sub scale prototype can demonstrate it's what it cannot. Those things can only be demonstrated in the full size vehicle, IE a Skylon. So you're building a Skylon (actually REL are planning 2 flight test Skylons) and  this demonstrator/proof-of-concept/whatever vehicle, so your overall budget goes up.  :(

My instinct is the simplest way to go is with full size SABRES propelling a reduced scale Skylon airframe with narrower, shorter fuselage, no payload bay (and no payload  :( ) and much lower propellant load.

If such a vehicle matches a full sized Skylons aerodynamics and mass properties then its results should be transferable directly to the full size Skylon, shortening the flight programme of the full sized vehicles to lower the overall development budget and "squaring the circle" of using 3 vehicles instead of 2 but still working out cheaper.   :)

IRL my instinct is that being able to scale a design to that way while preserving all the main features is a very big "if" indeed. I suspect the range over which you could scale the airframe while a)Using full size SABRES and b)keeping the various mass properties and aerodynamic coefficients matching the full size vehicle is very limited.

The question is not "can you scale it down" but "do you save so much on the test budget it's worth doing" ?

I suspect the answer comes out "Build a full size Skylon with full size engines and no payload bay (there is room, but only enough is installed to preserve necessary structural stiffness) and smaller tanks," and I think REL have a better idea of the answer, but I don't know what it is.  :(

But, as a thought exercise, a squished pancake shape might work. Internally, you have three rows of cylindrical spaces, center with payload bay and fore/aft LOx tanks flanked by full length LH2 tanks. Fit the SABRE equipment near the mid-fuselage edge of the pancake, with a 2D ramp inlet on its side, and exhaust is half an aerospike ramp on its side. That largely preserves the basic Skylon layout (which does well to deal with cg changes), but frontal area drag unfortunately goes up which goes against the partial cruise accelerator profile. The only advantage to that layout is if you were doing something kinky like receiving external heating AKA Laser Skylon, as you could have a better receiver area.
If cost is the issue for a prototype you'd scrap the payload bay. This layout might handle the Cp/Cg shifts well enough to do the whole flight trajectory.

But look what you've lost  :(

This design is reminiscent of the "pye wacket" missile concept for an armed SR71 but AFAIK it has no flight history in other vehicles you can call on to refine the design.

Then you're suggesting some altitude compensation by expansion against the underside, which raises the temperature quite a bit.

And once you've got it working how do you translate the measurement of the flight programme to that of a Skylon?

It's a tough problem.  :(

Very good discussion of various flight issues and body type trade offs. Couple of points:

Just a correction JS19 but the "Pye Wacket" lenticular missile was being designed for the XB-70, not the SR-71 :)

-An alternative Skylon design by the Centre for Future Air-Space Transportation Technology (cFASTT,)at the University of Strathclyde  has already come out suggesting various changes to enhance the "basic" design by REL.
http://www.strath.ac.uk/fastt/
https://www.facebook.com/cFASTTstrath/photos_stream?ref=page_internal
http://www.rocketeers.co.uk/node/3129
http://strathprints.strath.ac.uk/48572/1/Wuilbercq_R_et_al_Pure_Robust_multi_disciplinary_design_and_optimisation_of_a_reusable_launch_vehicle_Jun_2014.pdf

-As noted the main reason for the current suggested design of the Skylon is to reduce the aerodynamic variables that are associated with changes in CP/CG over the flight trajectory. However the design functions end up so that the basic design is almost "required" to be along certain lines. The engines are going to end up either under the airframe or on the wings, beyond that your airframe choices, due to the aim to reach minimum hypersonic (Mach-5) speed ends up being similar to Boeing Model 1074-xxxx (sometimes called the "Hyperdart") interceptor design. (Which was designed around the Mach-4.5 hydrocarbon/H2O2 propellant SERJ engine) Reference: http://www.secretprojects.co.uk/forum/index.php/topic,11580.0/all.html?PHPSESSID=2f9apo98c9kqtupnof6cmqo6u5

Which dates from the mid-60s hence the "needle" nose instead of the more common "shovel" nose you'd see today.

Much as I like the idea of a lenticular design ("Pye Wacket" see: http://www.rimworld.com/dsp/pyewacket.html, and http://aviationtrivia.blogspot.com/2010/05/in-1947-researchers-at-wright-patterson.html) as noted it doesn't lend itself well to hypersonic accelerator designs though it HAS been suggested in the past. (LM among others patented several designs for supersonic and hypersonic models in the 60s such as this: http://www.freepatentsonline.com/3066890.pdf, but you'll note how difficult fitting LH2 tanks into such a design would be. Moving the engines towards the outer sections and the tankage towards the middle induces intake issues and mounting the engines above or below the vehicle with a lenticular design offers none of the normal intake/exhaust compression/expansion advantages that a more dedicated (and normal layout) design would. And as noted higher drag and therefore heating would be an issue.

In the end the basic shape that REL has chosen for the baseline Skylon so they can have something to anchor their work in is what you're going to end up with in a very close approximation unless you have some compelling reason to go with a more radical airframe design. And the reason would have to be VERY compelling given the amount of data the "baseline" design has available.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 02/24/2015 10:47 pm
Very good discussion of various flight issues and body type trade offs. Couple of points:
Thank you.
Quote
Just a correction JS19 but the "Pye Wacket" lenticular missile was being designed for the XB-70, not the SR-71 :)
Oops. My memory playing tricks with me. I conflated the SR71 with the missile.
Quote
-An alternative Skylon design by the Centre for Future Air-Space Transportation Technology (cFASTT,)at the University of Strathclyde  has already come out suggesting various changes to enhance the "basic" design by REL.
http://www.strath.ac.uk/fastt/
https://www.facebook.com/cFASTTstrath/photos_stream?ref=page_internal
http://www.rocketeers.co.uk/node/3129
http://strathprints.strath.ac.uk/48572/1/Wuilbercq_R_et_al_Pure_Robust_multi_disciplinary_design_and_optimisation_of_a_reusable_launch_vehicle_Jun_2014.pdf

-As noted the main reason for the current suggested design of the Skylon is to reduce the aerodynamic variables that are associated with changes in CP/CG over the flight trajectory. However the design functions end up so that the basic design is almost "required" to be along certain lines. The engines are going to end up either under the airframe or on the wings, beyond that your airframe choices, due to the aim to reach minimum hypersonic (Mach-5) speed ends up being similar to Boeing Model 1074-xxxx (sometimes called the "Hyperdart") interceptor design. (Which was designed around the Mach-4.5 hydrocarbon/H2O2 propellant SERJ engine) Reference: http://www.secretprojects.co.uk/forum/index.php/topic,11580.0/all.html?PHPSESSID=2f9apo98c9kqtupnof6cmqo6u5

Which dates from the mid-60s hence the "needle" nose instead of the more common "shovel" nose you'd see today.
Given the advances in supersonic and hypersonic flow heating analysis is the "needle nose" even plausible today?
Quote
In the end the basic shape that REL has chosen for the baseline Skylon so they can have something to anchor their work in is what you're going to end up with in a very close approximation unless you have some compelling reason to go with a more radical airframe design. And the reason would have to be VERY compelling given the amount of data the "baseline" design has available.
Indeed. Once  you consider the full list of constraints a design must meet the options are quite limited.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 02/24/2015 11:41 pm
and in fact does not require Liquid Hydrogen [...]
Exhaust IR mitigation IS a possible use but again mitigation doesn't "require" the use of liquid hydrogen

Neither does Bond's heat exchanger. Indeed the major testing has not been with LH on the cold-side of the He-loop. LH is a requirement for Skylon because of the hypersonic operating environment where they need around 1000°C cooling (as would most hypersonic applications, for the same reason.) Outside of that operating environment, you pick the coolant to suit the application.

The key to Bond's idea is a) that it's frostless, b) that it's fast, and c) that it's both hot- and cold-side agnostic. The first lets you use where you can't use other heat-exchanges, the second means it acts almost like a thermal-superconductor (it will near-instantly cool the hot-side close to the temp of whatever is on the cold-side), the last means it's flexible for more applications. A bonus is that it's ridiculously light as a side-effect of (b).

[I do like how now I'm arguing that REL understands their pre-cooler well enough to model applications, while you're arguing that they've been a little premature/overenthusiastic...]
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 02/25/2015 12:48 pm
Which dates from the mid-60s hence the "needle" nose instead of the more common "shovel" nose you'd see today.
Given the advances in supersonic and hypersonic flow heating analysis is the "needle nose" even plausible today?

Actually yes. Needs some "tweeks" but really the only "difference" between the styles is how much they effect overall fore-body compression and acceleration profile.

and in fact does not require Liquid Hydrogen [...]
Exhaust IR mitigation IS a possible use but again mitigation doesn't "require" the use of liquid hydrogen

Neither does Bond's heat exchanger. Indeed the major testing has not been with LH on the cold-side of the He-loop. LH is a requirement for Skylon because of the hypersonic operating environment where they need around 1000°C cooling (as would most hypersonic applications, for the same reason.) Outside of that operating environment, you pick the coolant to suit the application.

To be more clear and specific pre-cooling and thrust augmentation doesn't even require a heat exchanger. But overall I think we're saying the same thing.

Quote
The key to Bond's idea is a) that it's frostless, b) that it's fast, and c) that it's both hot- and cold-side agnostic. The first lets you use where you can't use other heat-exchanges, the second means it acts almost like a thermal-superconductor (it will near-instantly cool the hot-side close to the temp of whatever is on the cold-side), the last means it's flexible for more applications. A bonus is that it's ridiculously light as a side-effect of (b).

[I do like how now I'm arguing that REL understands their pre-cooler well enough to model applications, while you're arguing that they've been a little premature/overenthusiastic...]

Sorry if that was the impression of what I was saying but I'm NOT actually arguing RELs process or methods I'm simply pointing out that their process/methods are designed towards their needs and models. I was pointing out that there are other methods of achieving similar results. And I'm in no way arguing that those other methods are applicable to RELs work as they are obviously not though the results and data obtained from the earlier work IS applicable for REL's modeling purposes.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Moe Grills on 02/25/2015 04:05 pm
   Right!   Since I never consider WORDS or DEBATE to be equivalent to proof, I patiently await the suborbital test-flight of the aerospace frame that will ATTEMPT to use the scaled down version of the SABRE engine before this decade is out.  Only until then will I consider this advanced technology to be feasible or not, practical or not.


I repeat the sentence fragment, "before this decade is out", noting that it was used by JFK to push a project that made history, revolutionized technology and achieved an ambitious goal. Perhaps it may apply to the SKYLON/SABRE. We hope!  Fingers crossed.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 02/25/2015 04:48 pm
@Moe Grills
They're building a full-size SABRE. Not a scaled down version. The costs and difficulties involved in the engineering of the engine mean that a full-sized engine makes more sense.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Moe Grills on 02/25/2015 07:06 pm
@Moe Grills
They're building a full-size SABRE. Not a scaled down version. The costs and difficulties involved in the engineering of the engine mean that a full-sized engine makes more sense.

I guess size matters, maybe.
BTAIM, If it works, bully to Mr. Bond and his engineering disciples; a spaceflight revolution can then begin sometime next decade.  If it doesn't work,  alas, humanity will have to plod along with conventional boosters for another century perhaps.
Fingers crossed that it may work as advertised.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 02/25/2015 07:10 pm
@Moe Grills
They're building a full-size SABRE. Not a scaled down version. The costs and difficulties involved in the engineering of the engine mean that a full-sized engine makes more sense.

I guess size matters, maybe.
BTAIM, If it works, bully to Mr. Bond and his engineering disciples; a spaceflight revolution can then begin sometime next decade.  If it doesn't work,  alas, humanity will have to plod along with conventional boosters for another century perhaps.
Fingers crossed that it may work as advertised.

Well for one thing it will cut down a small bit on the people who will still refuse to believe the engine will work because "it's ONLY a scale-model" :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 02/25/2015 08:26 pm
Well for one thing it will cut down a small bit on the people who will still refuse to believe the engine will work because "it's ONLY a scale-model" :)
But only a small bit  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 02/25/2015 08:45 pm
IIRC the plan for SCEPTRE is a full size prototypes/demonstrator rengine  but it will not be laid out to fit inside the cowling - more like a breadboard than something you could fly. Anyone know if that's correct? I'm also not sure if SCEPTRE will include thrust chambers and/or nozzles, but I'm going to guess not.

If it is not tightly packaged as it will be in the cowling then that will make it easier to troubleshoot and tweak. But doesn't a lot hinge on the plumbing/flow properties and thermal cycles that are influenced by layout? If so, will that necessitate a SCEPTRE 2.0?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 02/25/2015 09:40 pm
AFAIK they've decided to skip sceptre and go straight to developing a fully integrated full-size SABRE. 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 02/25/2015 09:54 pm
IIRC the plan for SCEPTRE is a full size prototypes/demonstrator rengine  but it will not be laid out to fit inside the cowling - more like a breadboard than something you could fly. Anyone know if that's correct? I'm also not sure if SCEPTRE will include thrust chambers and/or nozzles, but I'm going to guess not.

If it is not tightly packaged as it will be in the cowling then that will make it easier to troubleshoot and tweak. But doesn't a lot hinge on the plumbing/flow properties and thermal cycles that are influenced by layout? If so, will that necessitate a SCEPTRE 2.0?

I agree with your views on the full scale engine being a (breadboard) design. Building a full size engine with no restrictions on fitting into a cowling is sensible, just prove it works and leave a R/R type company to carry out the design needed to fit into the cowling and any further work needed to produce a flight ready engine. I am certain this will produce an  engine for ground tests much sooner.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 02/25/2015 11:12 pm
LH is a requirement for Skylon because of the hypersonic operating environment where they need around 1000°C cooling (as would most hypersonic applications, for the same reason.) Outside of that operating environment, you pick the coolant to suit the application.

True.  But in the case of aircraft propulsion specifically, hydrogen is far and away the best match.  It could still make sense with a different fuel, but I don't really see it as a game-changer.

When flying at Mach 5, SABRE - even the latest version - uses far more hydrogen for cooling than the core can burn.  The excess has to be burned at lower efficiency in a bypass ramjet.  Now consider that liquid hydrogen's heat soak capability per unit of combustion energy is at least double that of jet fuel.  By the time you got the speed down to the point where you weren't wasting fuel, you'd be getting close to the range accessible to existing engine technology without precooling - which is faster than any modern aircraft actually flies, there being other reasons not to bother going that fast.

On the other hand, even flying at Mach 3 or so, you might get a substantial improvement in T/W and perhaps SFC from being able to deal with air at about room temperature rather than at 350°C (of course the advantage would have to be great enough to justify the additional weight, cost, and maintenance overhead of the precooler and associated systems).  But a subsonic engine wouldn't gain much without a cryogenic propellant.

Dumping the heat while retaining the coolant isn't really an option as far as I can tell.  A water-cooling loop using the skin of the airframe as the cold side would still be well over an order of magnitude short of the heat transfer rate required, unless I messed up my quick ballpark calculation...

Building a full size engine with no restrictions on fitting into a cowling is sensible, just prove it works and leave a R/R type company to carry out the design needed to fit into the cowling and any further work needed to produce a flight ready engine.

Reaction Engines plans to build the engines themselves.  And while I could be wrong, I do think their full-scale engine will be in proper cowling form factor, based on how they've described it in contrast to the "dissected rabbit" that was SCEPTRE.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 02/26/2015 12:12 am
Interesting - I missed the change away from the 'dissected rabbit'. Hopefully that's indicative of confidence in all the theoretical and simulation work they've done, rather than impatience.

Any idea if what they're building includes everything, i.e. combustion chambers, nozzles, bypass burners, etc?

And does this match up with the phasing they mentioned in 2013 - where 3a included SCEPTRE? A near-flight-worthy engine is much more ambitious (expensive) than what I was expecting.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 02/26/2015 08:51 am
Interesting - I missed the change away from the 'dissected rabbit'. Hopefully that's indicative of confidence in all the theoretical and simulation work they've done, rather than impatience.

Any idea if what they're building includes everything, i.e. combustion chambers, nozzles, bypass burners, etc?

And does this match up with the phasing they mentioned in 2013 - where 3a included SCEPTRE? A near-flight-worthy engine is much more ambitious (expensive) than what I was expecting.

From Jeremy Nickless' talk last December http://forum.nasaspaceflight.com/index.php?topic=34964.msg1298468#msg1298468

Quote from: SICA Design
Phases 3 & 4 of the £10bn project now stretch over 10.5 years, of which £3.64bn is for SABRE. Phase 3 (£0.36bn) commenced April 2014 and approximately £100m has been secured, with approx £250m to secure in the next few years. Phase 4 is due to commence October 2018, with a (new) Skylon in-service date of October 2024.

Valkyrie? - "Could not possibly comment on that". Phase 3 WILL however involve a flying SABRE engine (not Skylon).
:
:
Quote
My impression was a single full-size SABRE with wings and tank
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 02/26/2015 10:16 am
Valkyrie? - "Could not possibly comment on that". Phase 3 WILL however involve a flying SABRE engine (not Skylon).
My impression was a single full-size SABRE with wings and tank
If you're not going with something looking like a Skylon you loose pretty much any benefits from getting early test data you can apply to the full vehicle  :(

Building one engine should be cheaper than two but with minimum order quantities, and discounts for buying large blocks, I'm not sure it would be that much cheaper.

You're now looking at something a long way from the Skylon. How big a problem that is depends on what speed range you're operating over.

 The issue would seem to be the air breathing to rocket transition at about Mach 5.5. A flying test vehicle (if it looks nothing like a Skylon it's not a prototype) operating up to say Mach 6 could be used to fine tune the Nacelle structure (like the NTV) and demonstrate the switchover to rocket mode before circling round to come back for a landing.

Following the rule of X-plane design that the only advanced technology you are using is the technology you're testing in the first place they should probably avoid the SiC reinforced Titanium space frame and PyroSic skin of a full Skylon.

M6 is in X15 territory, a vehicle designed to study prolonged airframe heating effects (when the whole airframe is cooked through). half a century later designing a vehicle for short duration flight at this speed (as it turns around to head for home) should not be beyond skills of a competent design team, especially given the commercial availability of things like Reinforced Carbon Carbon (and the flat plate techniques pioneered in the SHAFEX 1 and 2 programmes by DLR)

An interesting question would be if the vehicle is that much lighter and simpler (I don't think it'll be having a 15 tonne payload bay for starters  :( ) could it run on something other than LH2? Personally I hope not as this would reduce the "traceability" of the design to SABRE/Skylon design

Personally I'd like to see it make orbit and return. Such a "whole trajectory" demonstration would be hugely impressive and dramatically move the goalposts on the question "Is SSTO possible?"

No I don't think there's any chance of that happening.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 02/26/2015 10:35 am
My impression was a single full-size SABRE with wings and tank
If you're not going with something looking like a Skylon you loose pretty much any benefits from getting early test data you can apply to the full vehicle  :(

My impression could (of-course) be completely wrong, but it would advance REL's position (as engine mfg) and separate the issues of Skylon from SABRE.

Successful testing of SABRE through air and vacuum would surely encourage airframers to get onboard with Skylon development. It would be one further huge landmark in RELs track record of delivering what they claim.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 02/26/2015 11:30 am
My impression could (of-course) be completely wrong, but it would advance REL's position (as engine mfg) and separate the issues of Skylon from SABRE.

Successful testing of SABRE through air and vacuum would surely encourage airframers to get onboard with Skylon development. It would be one further huge landmark in RELs track record of delivering what they claim.
It's a swings and roundabouts problem.  :(

Yes you get early evidence that SABRE 4 engine can run up to at least M6 (I don't really see much point if the demonstrator doesn't go at least that high) you're still left with building 3 vehicles when they were expecting to build 2.  There is also the issue that anyone with serious money to put into the project will have had a technical evaluation done anyway and would not expect this to be a problem in the first place.

But you're right it would be another land mark that demonstrates that (when funded) REL can deliver what they say when they say.

Don't misunderstand me. I would love to see a demonstrator sooner rather than later but the whole budget is very large. If they can do it without enlarging it further that would be great

My feeling around forming the Skylon consortium is to find some way to get potential customers to sign an agreement with REL that can be passed to the consortium (when formed)  effectively saying

"We (country, corporation or other entity) agree to buy X Skylons at $Ym in 20xx prices(adjusted to the inflation up to the purchase date) and a support contract at $Zm in 20xx prices(adjusted to the inflation up to the purchase date) subject to it meeting the specification listed below from the entity REL have passed this to"

If enough of these were obtained it would act as a)A big incentive for the members to join the consortium (as they'd know already there is  the customer base exists) and b)Banks could see there were customers already waiting to buy them, lowering the investment risk.

Note at that point No money has changed hands, it's simply the demonstration that there is demand  out there.

That still leave plenty of problems. Have you got enough "pledges" to buy to cover the whole development cost? Can you build Skylons for that price and make a profit? If there is a time clause can you get Skylon flying before the pledge expires?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 02/26/2015 02:16 pm
I'm sure this is ridiculous for many reasons but:   Could SABRE be tested by bolting it on to or into some existing airframe as is done with new jet engines?

I presume full power would not be possible unless perhaps for fractions of a second and the maximum speed would have to be very low compared to SABRE's potential hence perhaps it's completely nonsensical?

Would there be anything to gain from this?  e.g. behaviour at various altitudes, ability to restart ...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: aga on 02/26/2015 02:41 pm
what existing aircraft uses lh2?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 02/26/2015 02:48 pm
I'm sure this is ridiculous for many reasons but:   Could SABRE be tested by bolting it on to or into some existing airframe as is done with new jet engines?

I presume full power would not be possible unless perhaps for fractions of a second and the maximum speed would have to be very low compared to SABRE's potential hence perhaps it's completely nonsensical?

Would there be anything to gain from this?  e.g. behaviour at various altitudes, ability to restart ...
You're perhaps thinking of the Olympus engine tests for Concorde, where (IIRC) a test engine for the Concorde version was mounted underneath a Vulcan bomber (powered by 4 more of them). IE roughly 1/4 the full thrust of the aircraft, Or the LASRE tests planned for NASA's SR71 in the X33 programme.

The trouble is a full size SABRE has roughly 4.5x the thrust of all the engines on an Airbus 380, and that won't even get you to Mach 1.  :(

You're pretty much going to build some sort of airframe around it (or underneath it).

Unobstructed airflow is going to be a big issue with this. The best (simplest) ideas I can come up with are putting wings on either side of single nacelle (about the simplest possible structure but a lot of stuff has to go inside those wings like fuel and landing gear)  or something like a V1, with a minimal body to limit flow obstruction at the back.

In principle the narrower the Mach range (and the lower the payload) the less you have to worry about the Cp/Cg shifts that drove the Skylon design in the first place but building a single engine vehicle which has adequate  airflow over a wide enough Mach range to be useful is (I think) going to be very tricky.  :(

My heart likes the idea of an early flight test vehicle with a (pair ?) of full size SABREs but my head says either the overall budget gets bigger or they fund from cuts from elsewhere, and it seems nothing is in the budget that doesn't need to be there already.   :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: NovaSilisko on 02/26/2015 03:01 pm
what existing aircraft uses lh2?

I've now got silly visions of a large airliner with one engine replaced with a SABRE, and another replaced with an aerodynamic LH2  tank...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 02/26/2015 03:18 pm
what existing aircraft uses lh2?

I've now got silly visions of a large airliner with one engine replaced with a SABRE, and another replaced with an aerodynamic LH2  tank...

I was going to point that out but IIRC there is a converted 707 with an LH2 tank in the boneyard from testing done in the early 70s.

However you'd really need a dedicated airframe unless you're JUST testing subsonic and takeoff/landing characteristics which is of limited value. You could go as far as mounting it to the side of an air-cargo aircraft and installing an LH2 tank in the cargo bay but the utility is limited at best.

I suspect JS19s idea is about what you'll get for flight testing.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 02/26/2015 03:43 pm
You're perhaps thinking of the Olympus engine tests for Concorde, where (IIRC) a test engine for the Concorde version was mounted underneath a Vulcan bomber (powered by 4 more of them). IE roughly 1/4 the full thrust of the aircraft, Or the LASRE tests planned for NASA's SR71 in the X33 programme.

The trouble is a full size SABRE has roughly 4.5x the thrust of all the engines on an Airbus 380, and that won't even get you to Mach 1.  :(

I wonder, could they build a full-scale SABRE but 1/4 power, i.e. fit some dummy (blanking) HX modules, only fit 1-of-4 combustion chambers / nozzles. Not sure how this would affect the compressor and other cooling loop / turbo machinery. Aim being to reduce power to suit smaller airframe, but still get relevant test results from full-scale components.

Any merit to this?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 02/26/2015 04:30 pm
We've certainly heard that the back end of SABRE is in essence two rocket engines driving four thrust chambers, and shutting down two of them is a planned failure mode. If that's still the case, half power in the test engine should be easy enough, and then add in whatever throttle-range it has.

Has minimum throttleable thrust ever come up before? This might be another reason to prefer E/D nozzles. IIUC wthout them Skylon startup thrust will need to be higher, and with SABRE's separated on wing-tips assymmetrical startup would be problematic.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 02/26/2015 04:54 pm
Interesting - I missed the change away from the 'dissected rabbit'. Hopefully that's indicative of confidence in all the theoretical and simulation work they've done, rather than impatience.

Any idea if what they're building includes everything, i.e. combustion chambers, nozzles, bypass burners, etc?

And does this match up with the phasing they mentioned in 2013 - where 3a included SCEPTRE? A near-flight-worthy engine is much more ambitious (expensive) than what I was expecting.

From Jeremy Nickless' talk last December http://forum.nasaspaceflight.com/index.php?topic=34964.msg1298468#msg1298468

Quote from: SICA Design
Phases 3 & 4 of the £10bn project now stretch over 10.5 years, of which £3.64bn is for SABRE. Phase 3 (£0.36bn) commenced April 2014 and approximately £100m has been secured, with approx £250m to secure in the next few years. Phase 4 is due to commence October 2018, with a (new) Skylon in-service date of October 2024.

Valkyrie? - "Could not possibly comment on that". Phase 3 WILL however involve a flying SABRE engine (not Skylon).
:
:
Quote
My impression was a single full-size SABRE with wings and tank

Thanks. You know, for a project that's not due until the mid 2020s we generate a lot of messages!

I would love to know how much of the 'build a flying SABRE' plan is dependent on the next £250m coming in, and what happens if it's late, or doesn't materialise. Here are a couple of options, one very cautious, and one not:

1] Spend the £100m to complete more ground-based component testing. Start work on the flyable Skylon when/if the £250m comes in. If it hasn't showed up when the £100m has been spent, REL goes into quiet mode awaiting money. Alan Bond retires soon thereafter, but the company continues.

2] Start spending the £100m to get ~ 1/3 of the way to a flying SABRE. If no-ones comes forth with the needed £250m to finish it, wasting that £100m will not reflect well on REL.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 02/26/2015 06:50 pm
I would love to know how much of the 'build a flying SABRE' plan is dependent on the next £250m coming in, and what happens if it's late, or doesn't materialise. Here are a couple of options, one very cautious, and one not:

1] Spend the £100m to complete more ground-based component testing. Start work on the flyable Skylon when/if the £250m comes in. If it hasn't showed up when the £100m has been spent, REL goes into quiet mode awaiting money. Alan Bond retires soon thereafter, but the company continues.

2] Start spending the £100m to get ~ 1/3 of the way to a flying SABRE. If no-ones comes forth with the needed £250m to finish it, wasting that £100m will not reflect well on REL.
The obvious route is to build and test the engine on the ground but plan the necessary features for it to be installed in an airframe.

REL have shown they are very careful at structuring the work they have to do relative to the funds they have.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 02/26/2015 07:02 pm
Sounds sensible. I wonder how much of a ground-based SABRE they can build for the £100m they have in hand. If most/all, we can reasonably expect to see something engine-shaped being built in Oxford over the next few years.

Edit: just went back to the January press release, and that says static test 'before the end of the decade.' So the flying SABRE test vehicle is early 2020s, which leads me to think that the additional £250m is needed to get through the static test.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: space_britannia on 03/01/2015 03:14 am
2) deliver the specifically designed lander into space, and bring the squad there when it is needed.

The lander-in-orbit would be limited to a single window in a single orbital plane, making it incompatible with the goal of a suborbital ballistic "drop-ship" to allow any point-to-point travel in 90 minutes or so.

Just to make sure everyone's on the same page, the actual SUSTAIN/Hot Eagle requirements had the vehicle being capable of P2P travel OR being put into orbit as a "standby" measure for "drop" at any point up to several days later.

The conflicting requirements of those two mission parameters were something that was never addressed and would drive a "vehicle" design that would be very costly to meet both requirements.

Randy

Just considering the first one then, since they would seem impossible to reconcile, what they have in mind would seem to be an LH2-fuelled skylon-like carrier, dropping a jet-fuelled lander (since ability to retrieve troops and craft was a desired characteristic), equipped with heat shielding.

Even if a suitable heat shield material was available, the main problem seems to be with the skyon-like carrier - what happens to it after release? If it goes to orbit once-around, then maximum payload for the lander is limited to in the region of Skylon's 15 tons. If it is on a suborbital trajectory, it would re-enter in uncontrolled airspace, and would have to be refuelled at a LH2-capable runway.
 
Build a heat-shielded jet aircraft lighter than 15 tons or maintain a network of LH2-capable runways in hostile regions, neither seems particularly feasible
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/01/2015 09:27 am
Build a heat-shielded jet aircraft lighter than 15 tons or maintain a network of LH2-capable runways in hostile regions, neither seems particularly feasible
Correct.

The CRADA is about specifically about the SABRE engine cycle.

If they'd wanted Hypersonic cruise I'm quite sure they'd have requested more information on the LAPCAT work for M5 cruise.

Put it this way, if they are not looking at SABRE for use in a launch vehicle they are very foolish.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 03/01/2015 02:31 pm
If it's just the engine cycle itself, ie the thermodynamic cycle, then it probably doesn't need to include any specific  information on the heat exchangers and frost control mechanisms.

And is it the SABRE 3 or SABRE 4 engine cycle?

What might the USAF gain from studying the thermodynamics of the engine cycle?  ie what applications or insights might it give them for future planning? Is it like JS19 suggests - the only real reason for studying the cycle in this engine is to look at possible applications for launch capacity only.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/01/2015 05:37 pm
If it's just the engine cycle itself, ie the thermodynamic cycle, then it probably doesn't need to include any specific  information on the heat exchangers and frost control mechanisms.
It will contain specific information regarding things like mass flow rates, temperature differences and inlet and out let temperatures (on both fluids). At this level it's mathematics. How those features are implemented is another question entirely.
Quote
And is it the SABRE 3 or SABRE 4 engine cycle?
This has been mentioned. It'll be SABRE 3 as that can be compared with the work funded by ESA and done at the Von Karman institute. That means the USAFRL can set up the same input conditions and expect the same output conditions. If that doesn't happen then someone has implemented the model of the engine wrong, which is a very handy thing to find out.

AFAIK the detailed performance of the SABRE 4 cycle are still private to REL.
Quote
What might the USAF gain from studying the thermodynamics of the engine cycle?  ie what applications or insights might it give them for future planning? Is it like JS19 suggests - the only real reason for studying the cycle in this engine is to look at possible applications for launch capacity only.
Have seen how much the USAF spends on launch only.

Gwen Shotwell at her NATO presentation said to the effect that "National Security Space launch is the US space launch market and you have to be in it to a major player in US space launch."
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: MichaelBlackbourn on 03/01/2015 06:00 pm
Any chance we can hack a ramp into the bottom of the payload bay for paratrooper deployment? Baumgartner up some airborne troops and fire them off the back of the ramp.

How does the payload bay compare to a c130 in number of troopers. And can the craft slow down long enough and low enough to deploy them and then land far downrange? :)

Or maybe a disposable frame that gets ejected and then drops the troops.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 03/01/2015 06:36 pm
JS19
**It'll be SABRE 3**

I missed that info. Thanks. :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: space_britannia on 03/01/2015 07:51 pm
Build a heat-shielded jet aircraft lighter than 15 tons or maintain a network of LH2-capable runways in hostile regions, neither seems particularly feasible
Correct.

The CRADA is about specifically about the SABRE engine cycle.

If they'd wanted Hypersonic cruise I'm quite sure they'd have requested more information on the LAPCAT work for M5 cruise.

Put it this way, if they are not looking at SABRE for use in a launch vehicle they are very foolish.  :(

Clearly they are looking at launch rather than hypersonic cruise, my question is if it is SUSTAIN they have in mind then how are they going to make this sabre carrier / turbojet lander architecture work
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/02/2015 08:33 am
Clearly they are looking at launch rather than hypersonic cruise, my question is if it is SUSTAIN they have in mind then how are they going to make this sabre carrier / turbojet lander architecture work
Welcome to the forum.

The answer is rather obviously with extreme difficulty. :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/02/2015 10:05 pm
Any chance we can hack a ramp into the bottom of the payload bay for paratrooper deployment? Baumgartner up some airborne troops and fire them off the back of the ramp.

How does the payload bay compare to a c130 in number of troopers. And can the craft slow down long enough and low enough to deploy them and then land far downrange? :)

Or maybe a disposable frame that gets ejected and then drops the troops.
Welcome to the forum.

The bay is about  4.8m wide and about 16 m long. There is no option for a "tail ramp" type drop.

Unfortunately you're either going to need various bases at different longitudes to minimize plane change payload losses or  you have a fairly small minimum team the system can use.

If the vehicle is staying orbital to land further along track or plane change back to its launch base that means the personnel are carrying out individual reentries, or you have to do an orbital ejection of a re entry capable lander module while keeping the vehicle in tact. Either way a huge challenge.  Probably the closest to this architecture is the "Q bay" of the U2 and it's developments, built as a simple rectangular duct running top to bottom, but I'm not sure what facilities it supplied to the payload or if they were more or less self contained.

Option B is to have the vehicle already into a reentry so a chunk of velocity is already lost. Now you're looking at something like an ejection. The highest is about M3 from an SR71, however it seems due to the altitude (around 80 k feet) which apparently equates to something like 400mph.

This is one of those sounds-cool-but-is-really-nonsense ideas that's great for the plot of a straight-to-download action movie.

IRL not really that good.  :(

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 03/03/2015 11:51 am
UK ministers issue spaceport shortlist:-

http://www.bbc.co.uk/news/science-environment-31711083

Three of the 6 shortlisted sites have runways under 3000m, with implications for Skylon unless rectified.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 03/03/2015 11:58 am

UK ministers issue spaceport shortlist:-

http://www.bbc.co.uk/news/science-environment-31711083

Three of the 6 shortlisted sites have runways under 3000m, with implications for Skylon unless rectified.

Already a dedicated thread for this.

http://forum.nasaspaceflight.com/index.php?topic=35163
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/03/2015 12:40 pm
UK ministers issue spaceport shortlist:-

http://www.bbc.co.uk/news/science-environment-31711083

Three of the 6 shortlisted sites have runways under 3000m, with implications for Skylon unless rectified.
I don't think any of the runways have the necessary 5000m for a full Skylon runway.

Logically Newquay, being at a slightly lower longitude is best if you want direct launch to orbit. Otherwise I think most of then could handle Skylon payload loading and take off in air breathing mode.

OTOH as Hempsell pointed out all UK sites are bad for equatorial launch, but OK for polar launch, which is handy for some kinds of Earth observation missions.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 03/03/2015 02:57 pm

UK ministers issue spaceport shortlist:-

http://www.bbc.co.uk/news/science-environment-31711083

Three of the 6 shortlisted sites have runways under 3000m, with implications for Skylon unless rectified.
I don't think any of the runways have the necessary 5000m for a full Skylon runway.

Logically Newquay, being at a slightly lower longitude is best if you want direct launch to orbit. Otherwise I think most of then could handle Skylon payload loading and take off in air breathing mode.

OTOH as Hempsell pointed out all UK sites are bad for equatorial launch, but OK for polar launch, which is handy for some kinds of Earth observation missions.

This isn't really relative to REL as they didn't even respond to the consultation.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/03/2015 07:31 pm
And just to "tweak" the doubters again, ('cause its fun :) ) I was re-reading "Facing the Heat Barrier" again and found something I'd missed the first couple of time. Seems Lockheed has done some work on a "SABRE-like" engine for a 1962 space plane study with a system called "Tubo-LACE" (which was a misnomer as it didn't even USE LACE)

From “Facing the Heat Barrier” chapter 4, page 119:
“For takeoff, Lockheed expected to use Turbo-LACE. This was a LACE variant that sought again to reduce the inherently hydrogen-rich operation of the basic system. Rather than cool the air until it was liquid, Turbo-Lace chilled it deeply but allowed it to remain gaseous. Being very dense, it could pass through a turbocompressor and reach pressures in the hundreds of psi. This saved hydrogen because less was needed to accomplish this cooling. The Turbo-LACE engines were to operate at chamber pressures of 200 to 250 psi, well below the internal pressure of standard rockets but high enough to produce 300,000 pounds of thrust by using turbocompressed oxygen.”

All under the "Aerospaceplane" study effort that was sponsored by the Air Force looking for an air-breathing launch platform :)

As an additive "thunk" experiment, I was wondering if a modified REL HE could work effectively in reverse? (Using suitable materials of course) Having a "hot" heat exchanger in the place of a normal combustion chamber to provide heating of the air. I recall there was some work done by a small Canadian company on such a design for use with alternative fuels for aircraft engines though I can find nothing at the moment on it. The idea was you could use less than ideal fuels to provide thrust through the HE concept rather than burning the fuels directly in the airstream. Mostly because some fuels (peanut oil IIRC was one suggested fuel) don't burn in a high speed airstream as well as kerosene products, but some mention was made that heating a supersonic airflow (yes getting into my "favorite" engine cycle here the SCramjet :) ) without causing shockwaves due to injected fuel.

Probably impractical but discussions with someone on using an "electric fan fed" jet engine got me to thinking...

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/03/2015 08:31 pm
Build a heat-shielded jet aircraft lighter than 15 tons or maintain a network of LH2-capable runways in hostile regions, neither seems particularly feasible
Correct.

The CRADA is about specifically about the SABRE engine cycle.

If they'd wanted Hypersonic cruise I'm quite sure they'd have requested more information on the LAPCAT work for M5 cruise.

Put it this way, if they are not looking at SABRE for use in a launch vehicle they are very foolish.  :(

And one thing the US in general and our military specifically is NEVER is foolish by assumption :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/03/2015 08:47 pm
If it's just the engine cycle itself, ie the thermodynamic cycle, then it probably doesn't need to include any specific  information on the heat exchangers and frost control mechanisms.

And is it the SABRE 3 or SABRE 4 engine cycle?

What might the USAF gain from studying the thermodynamics of the engine cycle?  ie what applications or insights might it give them for future planning? Is it like JS19 suggests - the only real reason for studying the cycle in this engine is to look at possible applications for launch capacity only.

"Deep-cooled" airflow is actually useful in applications NOT related to launch but not many. On the other hand NO thermodynamic data is useless so even if the USAF is not interested in SABRE as a cycle or for launch purposes there's information to be had :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/03/2015 09:11 pm
Any chance we can hack a ramp into the bottom of the payload bay for paratrooper deployment? Baumgartner up some airborne troops and fire them off the back of the ramp.

How does the payload bay compare to a c130 in number of troopers. And can the craft slow down long enough and low enough to deploy them and then land far downrange? :)

Or maybe a disposable frame that gets ejected and then drops the troops.
Welcome to the forum.

The bay is about  4.8m wide and about 16 m long. There is no option for a "tail ramp" type drop.

Not wanted or needed for supersonic drops anyway the air "above" the airframe is less disturbed and smoother in a relative way. And to prevent serious scatter and/or injury you'd want to eject the personnel in a pod of some type. We (the US) actually did some studies of dropping troops from a B-58 using the under-slung pod in a wind tunnel. Again the major problem was you can drop a whole company and supplies from a sub-sonic C-130 and get the job "done" where as specialized insertion has much less margin for supplies and more troops. It would take as squadron of B-58s to put the same number of boots (and kit) on the ground as one C-130 and the C-130 does it more efficiently and accurately as well.
(BTW: Studies have been done on supersonic and even hypersonic troop and supply drop and while you can use a "tail-ramp" it ends up being on TOP of the airframe and you have to chuck the stuff past the shockwave with something like a catapult so again, not very effective overall. Oh and you have to actually "pressurize" the bay to prevent sucking the shockwave into the airframe in order to "open-up" at supersonic speeds)

In retrospect it would actually have been neat to be able to have the option of supersonic dash into AO, drop to high-subsonic and dump the payload pod, then dash back up to supersonic for egress. But you still have all the issues of inserting into hostile territory with minimum forces that is inherent in the system. Hmmm, something more like a supersonic "Pack-Plane" maybe? (http://en.wikipedia.org/wiki/Fairchild_XC-120_Packplane) But the differences between with and without aerodynamics would probably be prohibitive let alone hypersonic and/or suborbital...

And on top of it all you have an institutional dislike of cryogenic fluids if they can at all be avoided...

Quote
Unfortunately you're either going to need various bases at different longitudes to minimize plane change payload losses or  you have a fairly small minimum team the system can use.

If the vehicle is staying orbital to land further along track or plane change back to its launch base that means the personnel are carrying out individual reentries, or you have to do an orbital ejection of a re entry capable lander module while keeping the vehicle in tact. Either way a huge challenge.  Probably the closest to this architecture is the "Q bay" of the U2 and it's developments, built as a simple rectangular duct running top to bottom, but I'm not sure what facilities it supplied to the payload or if they were more or less self contained.

DROP TROOPERS! :)
U2: Power and air conditioning as far as I know. The constraints were that the equipment had to fit into the bay and work on the provided air and electric.

Quote
Option B is to have the vehicle already into a reentry so a chunk of velocity is already lost. Now you're looking at something like an ejection. The highest is about M3 from an SR71, however it seems due to the altitude (around 80 k feet) which apparently equates to something like 400mph.

This is one of those sounds-cool-but-is-really-nonsense ideas that's great for the plot of a straight-to-download action movie.

IRL not really that good.  :(

Still need a pod or something to hold the troops together unless they individually have some sort of propulsion and guidance. HALO's do something similar from similar altitudes but they have control over their positioning during drop which a supersonic drop would not have. (Imagine your "average" Marine's full kit. Now put a spacesuit on it and him and ask him to perform "simple" maneuvers in the gear. There's a reason the military was interested in the results of high altitude parachuting before Baumgartner did it :) )

And again you get about twice the useful payload to the target with a C-130 than you would with a Skylon under these circumstances...

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/03/2015 09:16 pm
Any chance we can hack a ramp into the bottom of the payload bay for paratrooper deployment? Baumgartner up some airborne troops and fire them off the back of the ramp.

How does the payload bay compare to a c130 in number of troopers. And can the craft slow down long enough and low enough to deploy them and then land far downrange? :)

Or maybe a disposable frame that gets ejected and then drops the troops.

Capacity: Skylon is this role would be around 15mT where as the C-130 delivers 33mt so about half what a C-130 could do and how much of it is going to be required for support and equipment to keep the troops safe from take off to "landing" is a key issue.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/03/2015 09:22 pm
Just considering the first one then, since they would seem impossible to reconcile,...

Welcome as well :)

Oh not "impossible" of course, what the military wants they will, usually, eventually get but really, really hard to reconcile to say the least :)

Quote
... what they have in mind would seem to be an LH2-fuelled skylon-like carrier, dropping a jet-fuelled lander (since ability to retrieve troops and craft was a desired characteristic), equipped with heat shielding.

Even if a suitable heat shield material was available, the main problem seems to be with the skyon-like carrier - what happens to it after release? If it goes to orbit once-around, then maximum payload for the lander is limited to in the region of Skylon's 15 tons. If it is on a suborbital trajectory, it would re-enter in uncontrolled airspace, and would have to be refuelled at a LH2-capable runway.

Or Tanker and air-to-air refueling. LH2 is still considered (and researched) as a possible aircraft fuel after all. And technically the Skylon could, if suborbital, still retain enough propellant to egress the insertion area and fly to meet such a tanker once all was said and done.

Quote
Build a heat-shielded jet aircraft lighter than 15 tons or maintain a network of LH2-capable runways in hostile regions, neither seems particularly feasible

Well a quick (few minutes) search of NTRS doesn't find what I'm looking for but I'll say the idea has been looked at before. Around 1965 IIRC there was a NASA tech-note on the idea of a orbital or suborbital system that had a reentry vehicle that deployed itself as a Mach-2 fighter or (5 or 6 person IIRC) aircraft once it entered the "area or operations" on arrival. Not in any way as efficient as a purpose built aircraft mind you but do-able as far as the study could tell.

The main problem with SUSTAIN/HOT-EAGLE wasn't that it was not possible but that the idea of inserting a handful (biggest body I ever saw mentioned was a company but the usual group was a squad) of troops with no heavy weapons or support and expecting them to actually DO anything even if no one noticed their arrival.

It was an attempt to replace stealth with speed with the idea that getting the troops to the "trouble" location within minutes of being alerted replacing getting enough troops and equipment to be effective and it didn't make a whole lot of sense from the start.

It's simply not enough force to do any job given that the insertion is so non-stealthy in the first place. A Marine recon squad "ready-to-go" massed more than the notional troops that were supposed to be inserted by the system and THEY get things like SF-stealth helicopters to ride in :)

Again the main issue is even if you got the troops there, intact with minimum or no notice by the locals they are very few and with no real equipment or support and no capability for self extraction or retrieval without additional resources already in place.

We've a thread on the concept IIRC if anyone wants to resurrect it but its been years. (Then again I don't think I ever got to fully explore some of the concepts that came around under that heading. The Falcon-9 with the with an aeroshell that landed a folded up Blackhawk and crew/soldiers was, I thought a nice attempt at addressing the issues :) )

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/03/2015 11:41 pm

In retrospect it would actually have been neat to be able to have the option of supersonic dash into AO, drop to high-subsonic and dump the payload pod, then dash back up to supersonic for egress. But you still have all the issues of inserting into hostile territory with minimum forces that is inherent in the system. Hmmm, something more like a supersonic "Pack-Plane" maybe? (http://en.wikipedia.org/wiki/Fairchild_XC-120_Packplane) But the differences between with and without aerodynamics would probably be prohibitive let alone hypersonic and/or suborbital...
This is OT but this idea still looks a sensible notion to maximize the use of expensive assets. I don't think anyone doubts that the ISO container has revolutionized how quickly goods can be be moved as holds no longer need to be individually loaded.
Quote
DROP TROOPERS! :)
U2: Power and air conditioning as far as I know. The constraints were that the equipment had to fit into the bay and work on the provided air and electric.
Which sounds like quite a fair trade off. The SR71 had the detachable nose and various sensors on pallets for the different bays but only the U2 had a full through  bay with no floor.
Quote
Still need a pod or something to hold the troops together unless they individually have some sort of propulsion and guidance. HALO's do something similar from similar altitudes but they have control over their positioning during drop which a supersonic drop would not have. (Imagine your "average" Marine's full kit. Now put a spacesuit on it and him and ask him to perform "simple" maneuvers in the gear. There's a reason the military was interested in the results of high altitude parachuting before Baumgartner did it :) )

And again you get about twice the useful payload to the target with a C-130 than you would with a Skylon under these circumstances...
I also think it's pretty clear that whatever such a vehicle would be it's definitely not a Skylon anymore.

TBH the "simplest" (and I use the word very loosely) would be to fly the Skylon upside down and drop the pot out the way it came in.

Conceptually simple but IRL insane  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Asteroza on 03/05/2015 06:49 am
UK spaceport selection shortens the short list...

https://www.gov.uk/government/news/industry-backs-governments-spaceport-plans (https://www.gov.uk/government/news/industry-backs-governments-spaceport-plans)

but still aiming at 3000m+ runway. Enough for build+ferry ops?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 03/05/2015 10:33 am
Approx. 97% off-topic:

http://en.wikipedia.org/wiki/Fairchild_XC-120_Packplane (http://en.wikipedia.org/wiki/Fairchild_XC-120_Packplane)
This is OT but this idea still looks a sensible notion to maximize the use of expensive assets. I don't think anyone doubts that the ISO container has revolutionized how quickly goods can be be moved as holds no longer need to be individually loaded.

The Packplane concept (and Skylon equivalent) is not analogous to ISO containers. Shipping containers are much smaller than the ships that carry them. Ditto palletised cargo that goes in a shipping container or truck box. The pallets/container are much smaller than the cargo-carrier so that you don't have to worry about the vehicle size. A 2 pallet van, a 2x2x5 pallet truck, a 2x2x10 pallet ISO shipping container...  A single 2-TEU skeleton trailer, a double-stack 2-TEU train carriage, a 36-TEU river barge, a 5,000-TEU Panamax, etc.

But there's no shipping equivalent of the Packplane, where you have a single removable module that becomes a ship's entire hold, even though ships similar to an empty Packplane (http://worldmaritimenews.com/wp-content/uploads/2012/01/China-CMHI-Delivers-Semi-submersible-Heavy-Lift-Vessel-HUAHAILONG.jpg) exist for other purposes, so it's not a structural issue. It would be simple to design a roll-on/roll-off giant freight module for such a ship, but each semi-submersible platform-ship is a unique size, therefore each giant freight module would be bespoke to each ship. You can see where this is going...

Similarly, instead of a Packplane, the air-freight equivalent of ISO containers are the much smaller ULD containers, light pallets with corner cutaways to allow them to stack against curved cargo-holds. (Likewise the US military have standardised on their own "master pallet".) A Packplane type system, OTOH, would be unique to each airframe and wouldn't really save you anything in airport handling. It would just add another step to go wrong, another set of equipment to buy to move the Packplane shell around, in addition to the equipment to load the shell (ULDs/master-pallets, forklifts, etc) and support the loaded and uploaded airframe.

The launch vehicle equivalent of pallets/ULDs/ISOs would be the cubesats and their racks and launchers. If launch vehicles ever became so large that they routinely shipped dozens of full scale (say 5t) satellites in a single launch, then I suspect something like a 2.4x2.4x2.4m "cubesat" standard would evolve. (2.4m/8ft is pretty common for 3+m shrouds, 4.8m/16ft for 5.5m shrouds. Makes a nice 1U, 2U standard.)

Without that, I don't think there's a an advantage in creating a single "Packplane" payload module for a launcher. It doesn't give you "aircraft-like operations". Operationally, it just increases the handling - integrate the payload into the container, then the container into the launcher. So the container is really just wasted payload.  It's different if you were routinely trying to integrate 10-20 separate payloads into a single HLV where a size-standardised payload-rack would improve operations enough to justify the rack's mass.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/05/2015 02:57 pm
Approx. 97% off-topic:

Probably closer to 98%+ but that's a quibble :)

>cut for brevity attempt :)<
Quote
The Packplane concept (and Skylon equivalent) is not analogous to ISO containers. Shipping containers are much smaller than the ships that carry them. Ditto palletised cargo that goes in a shipping container or truck box. The pallets/container are much smaller than the cargo-carrier so that you don't have to worry about the vehicle size. A 2 pallet van, a 2x2x5 pallet truck, a 2x2x10 pallet ISO shipping container...  A single 2-TEU skeleton trailer, a double-stack 2-TEU train carriage, a 36-TEU river barge, a 5,000-TEU Panamax, etc.

But there's no shipping equivalent of the Packplane, where you have a single removable module that becomes a ship's entire hold, even though ships similar to an empty Packplane (http://worldmaritimenews.com/wp-content/uploads/2012/01/China-CMHI-Delivers-Semi-submersible-Heavy-Lift-Vessel-HUAHAILONG.jpg) exist for other purposes, so it's not a structural issue. It would be simple to design a roll-on/roll-off giant freight module for such a ship, but each semi-submersible platform-ship is a unique size, therefore each giant freight module would be bespoke to each ship. You can see where this is going...

Similarly, instead of a Packplane, the air-freight equivalent of ISO containers are the much smaller ULD containers, light pallets with corner cutaways to allow them to stack against curved cargo-holds. (Likewise the US military have standardised on their own "master pallet".) A Packplane type system, OTOH, would be unique to each airframe and wouldn't really save you anything in airport handling. It would just add another step to go wrong, another set of equipment to buy to move the Packplane shell around, in addition to the equipment to load the shell (ULDs/master-pallets, forklifts, etc) and support the loaded and uploaded airframe.

The launch vehicle equivalent of pallets/ULDs/ISOs would be the cubesats and their racks and launchers. If launch vehicles ever became so large that they routinely shipped dozens of full scale (say 5t) satellites in a single launch, then I suspect something like a 2.4x2.4x2.4m "cubesat" standard would evolve. (2.4m/8ft is pretty common for 3+m shrouds, 4.8m/16ft for 5.5m shrouds. Makes a nice 1U, 2U standard.)

Without that, I don't think there's a an advantage in creating a single "Packplane" payload module for a launcher. It doesn't give you "aircraft-like operations". Operationally, it just increases the handling - integrate the payload into the container, then the container into the launcher. So the container is really just wasted payload.  It's different if you were routinely trying to integrate 10-20 separate payloads into a single HLV where a size-standardised payload-rack would improve operations enough to justify the rack's mass.

In general I agree.

The "Packplane" concept lives a proof of the "Bee-plane" (http://www.bee-plane.com/) but the issue is the fact that you have to make each "pod" the equivalent of an aircraft fuselage no matter WHAT the cargo is. That costs. At the time the Packplane was proposed you could almost get away with a "pod" being nothing more than a cheap metal tube on some car-wheels and a roof mounted hard point attachment. All well and good but as someone who's spent a great deal of time on board NORMAL transport aircraft with minimum insulation and sound proofing, (it looks funny but you can tell the folks going home in the desert because they show up for on the flight line in thermal underwear and parkas and are happy about it :) ) while it MIGHT work for the military for normal passenger or freight services you need more structure and support. And your cost ramps up fast. Plus there is the drag and other aerodynamic issues and the fact that you "core" aircraft is ONLY usable with the pod system and in the end the effort doesn't "seem" worth it.

Note the "quotes" there :) As shown by the Bee-Plane being only the latest example the idea won't go away and really, from studies done such a "pod" system might in fact be the future of civil passenger aviation. Someday :)
But the process isn't really applicable for space flight, not anytime soon at least.

Now I've seen some concepts (and patents thereof :) ) that involve hooking together actual ISO containers either onto fuselage or making a fuselage out of them and most look pretty dodgy for "regular" use but as Paul451 notes you COULD just simple stuff ISO containers into a detachable fuselage pod and call it done but it will not BE an "ISO container" aircraft anymore than a "container" ship is made out of containers :)

Standardized "Payload" pods though could be useful and probably will be but not any time soon I think. That kind of "containerization" of cargo takes a certain level of both throughput for a transportation system AND at least some degree of "standardization" of cargo loads as well. We're not there yet with space transport as no two satellites are exactly the "same" enough to allow a single standardized payload attachment and support system.

Except as noted (again) by Paul451; cubesats.

I don't think it's too far fetched to imagine that once access frequency goes up and costs come down that a similar architecture for larger satellites won't spring up and lead to a "standardized" payload module and interfaces.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Archibald on 03/06/2015 05:42 am
Quote
The Falcon-9 with the with an aeroshell that landed a folded up Blackhawk and crew/soldiers was, I thought a nice attempt at addressing the issues

WTF ??!!
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/06/2015 03:30 pm
Quote
The Falcon-9 with the with an aeroshell that landed a folded up Blackhawk and crew/soldiers was, I thought a nice attempt at addressing the issues

WTF ??!!

Impressive :) It only took three days for someone to catch that one. Yup, was a suggested approach I read on an engineering forum. Not QUITE as crazy as it sounds but not far off :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: tea monster on 03/06/2015 06:13 pm
Wow! Lock, n load, n launch soldier!

It would be great to be the only helo pilots on the planet with astronaut's wings!  ;)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Archibald on 03/08/2015 07:52 am
Quote
The Falcon-9 with the with an aeroshell that landed a folded up Blackhawk and crew/soldiers was, I thought a nice attempt at addressing the issues

WTF ??!!

Impressive :) It only took three days for someone to catch that one. Yup, was a suggested approach I read on an engineering forum. Not QUITE as crazy as it sounds but not far off :)

Randy

Do you have a link to that "engineering forum" ?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: tatarana on 03/10/2015 11:05 pm
As was said several times in this and the previous 4 threads, SABRE engine seems to scale down badly due to problems with the LH2 pump.
BUT... ???
What are the perspectives to scale it up, if (normal size) SABRE and Skylon fulfill its promises ?
There would be any limits to build a larger Skylon to send heavier payloads to orbit,
as for example, doubling payload to 30 tonnes ? An obvious one is the runway reinforced concrete pavement, but there are any fundamental limits ?
Also, what would be  possible economic reasons to scale it up ?

Tatarana
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 03/11/2015 03:19 am
http://forum.nasaspaceflight.com/index.php?topic=24621.msg735577#msg735577

Quote from: Hempsell
We have not seriously explored taking the SKYLON type vehicle up to the heavy lift class but the few “fun exercises” we have done have not shown any fundamental upper limit technically but the economics go to pot. Basically making the systems as small as possible while still capturing the main market (i.e. not small sats) throws the economic burden on to more launches (where reusables score) and off development cost and acquisition cost (where reusable suffer).

If the market for large payloads gets to the point where a bigger vehicle makes sense, someone will design one.  Kinda like how locks on the St. Lawrence Seaway have been replaced with bigger ones multiple times as shipping outgrew them.

Alternately, if someone with big plans and deep pockets decides they want a super heavy Skylon-type vehicle for their own purposes, they might pay to get one built; NASA and SpaceX are both doing this already with more conventional launcher technology.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/12/2015 10:05 pm
If the market for large payloads gets to the point where a bigger vehicle makes sense, someone will design one.  Kinda like how locks on the St. Lawrence Seaway have been replaced with bigger ones multiple times as shipping outgrew them.
Interesting analogy.

It's an interesting point that those locks were the right size for the bulk of the traffic at the time they were built, but really big ships would have to take the long way round.

Skylon won't deliver the biggest payloads to orbit but it will deliver the bulk of payloads. Will that matter? Time will tell.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: tatarana on 03/14/2015 03:40 pm
http://forum.nasaspaceflight.com/index.php?topic=24621.msg735577#msg735577

Quote from: Hempsell
We have not seriously explored taking the SKYLON type vehicle up to the heavy lift class but the few “fun exercises” we have done have not shown any fundamental upper limit technically but the economics go to pot. Basically making the systems as small as possible while still capturing the main market (i.e. not small sats) throws the economic burden on to more launches (where reusables score) and off development cost and acquisition cost (where reusable suffer).

If the market for large payloads gets to the point where a bigger vehicle makes sense, someone will design one.  Kinda like how locks on the St. Lawrence Seaway have been replaced with bigger ones multiple times as shipping outgrew them.

Alternately, if someone with big plans and deep pockets decides they want a super heavy Skylon-type vehicle for their own purposes, they might pay to get one built; NASA and SpaceX are both doing this already with more conventional launcher technology.

93143, thanks a lot for the refresher.  During  thread 1  I was still not able to follow the subtle points of arguments about space markets.  Skylon threads also have this nice characteristic of being a teaching tool.

JS19, your argument about 'bulk cargo' makes a lot of sense.
Question: if you take out the satellite market, what other bulk cargo could there be? Fuel to depots ?
Space station's construction components by other nations ?

Some time ago I read a nice paper about space mining, NEAR EARTH OBJECTS AS RESOURCES FOR SPACE INDUSTRIALIZATION, by MARK SONTER. He makes a strong argument by examining and comparing the mining industry on Earth with space use. One of his conclusions was that it could be possible to build a space craft mining unity that would weight something like 5 metric tonnes. I wonder if something like this could be crammed inside a Skylon  standard cargo module, perhaps with a suplementary deep space propulsion unit launched separately (perhaps  electric propulsion like Vasimr, that uses argon and hydrogen that could be mined and replenished  in situ). This subject has ever surfaced on Skylon threads ?

Tatarana
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/14/2015 04:59 pm
JS19, your argument about 'bulk cargo' makes a lot of sense.
Question: if you take out the satellite market, what other bulk cargo could there be? Fuel to depots ?
Space station's construction components by other nations ?
Welcome to the site.

In hindsight "bulk" might not have been the best word. Certainly Skylon can cover the majority of the known and expected payload growth in those known markets. That said the aggregate mass these missions put up easily exceed any single payload over time.

Actual bulk payloads are either things that need to be delivered in large volumes (or masses) or that cannot be sub divided. The former would be propellants, water, toilet tissue, ready meals. The latter would be things like large nuclear reactors or telescopes.

REL have done various studies to ensure that their vehicle can accommodate tasks as diverse as launching satellites to GEO, probes to other planets and their moons (while retaining the upper stage) and full blown Mars missions.

Quote
Some time ago I read a nice paper about space mining, NEAR EARTH OBJECTS AS RESOURCES FOR SPACE INDUSTRIALIZATION, by MARK SONTER. He makes a strong argument by examining and comparing the mining industry on Earth with space use. One of his conclusions was that it could be possible to build a space craft mining unity that would weight something like 5 metric tonnes. I wonder if something like this could be crammed inside a Skylon  standard cargo module, perhaps with a suplementary deep space propulsion unit launched separately (perhaps  electric propulsion like Vasimr, that uses argon and hydrogen that could be mined and replenished  in situ). This subject has ever surfaced on Skylon threads ?
The current Skylon revision is for a payload of 15 tonnes in a payload bay about 13m long and close to 5m in diameter. It's not that cramped, although the price would be set by the Skylon operators.

It should be big enough to accommodate such a payload.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 03/15/2015 09:57 pm
the issue with Skylon and asteroids mining is actually that miners expect to get most of their initial revenue from basic commodities, like water, which value per kg in space equals their launching cost per kg.

Skylon kills this business case by providing cheap access. it brings the value of water down from 14k $ per kilo, to 600 $ per kilo.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hanelyp on 03/16/2015 04:44 am
But bringing down launch costs also brings down the expense to deploy asteroid mining equipment.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 03/16/2015 06:35 am
Skylon kills this business case by providing cheap access. it brings the value of water down from 14k $ per kilo, to 600 $ per kilo.

Bringing down the cost of access to LEO increases the number of users who can justify access, which increases the number of users who can then justify BEO missions. (Even if its primarily university/govt research.) That creates a much larger initial market for water/air/fuel delivered to BEO facilities from local sources. That then lowers the cost of operations BEO, and increases the number of users who can justify going a step further out.

Additionally, the increase in users in LEO and BEO pays for the development of more HSF and robotic technology. That lowers the start-up cost for asteroid (and lunar-pole/Mars moons/etc) miners.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 03/18/2015 07:50 am
if demand for space is sufficiently elastic,yes.
But we don't know it yet.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 03/18/2015 03:47 pm
Apparently Jeremy Nickless gave a presentation at NSSC 2015 at the beginning of the month,


http://ukseds.org/nssc2015/?p=speakers

Anyone attend?

Anyway there are some slide pictures on twitter from it and this one seemed new to me:

https://twitter.com/Astro_Mona/status/572037016537444352/photo/1

I read it as saying in airbreathing mode SABRE consumes 900t of air for a deltaV of 5.2km/s, which is data point for SABRE 4 performance I don't think we had before.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 03/18/2015 10:15 pm
I'm seeing "Rocket ΔV=6.2km/s", which sounds about right given that C1 seems to have been about 6.3 km/s.  Airbreathing should be around 3.5-4 km/s if it's anything like C1, which according to my calculations was about 3.7 km/s.

900 tonnes of air is less than the 1250 tonnes or so C1 took in, but that includes the bypass flow; scaling the 530-tonne core flow by the increased mass of D1 still gives me only 650 tonnes.  If the new engine is substantially different, perhaps with a different trajectory-coupled-optimum thrust level, I can see how the number might have changed.  Or maybe it's per engine; one SABRE 3 seems to use close to 800 tonnes when scaled to the mass of D1.  Alternately, I could have done my math wrong; it's happened before...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Soundbite on 03/20/2015 06:44 pm
Just thought you might all be interested in the latest press release from reaction engines http://www.reactionengines.co.uk/press_release.html (http://www.reactionengines.co.uk/press_release.html).

Alan Bond is going to concentrate on being Chief Engineer and pass the reigns of Managing Director to a new appointee.

Maybe they are anticipating tougher competition ahead?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 03/20/2015 08:32 pm
The fact that they've hired the former Chief Engineer for Technology and Future Programmes with Rolls-Royce Civil Large Engines to be the new MD seems to me to be very positive news. And importantly an addition that potential investors would welcome.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/20/2015 10:08 pm
Just thought you might all be interested in the latest press release from reaction engines http://www.reactionengines.co.uk/press_release.html (http://www.reactionengines.co.uk/press_release.html).

Alan Bond is going to concentrate on being Chief Engineer and pass the reigns of Managing Director to a new appointee.

Maybe they are anticipating tougher competition ahead?
No, it means he wants to focus on the technology development.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 03/20/2015 10:22 pm
The fact that they've hired the former Chief Engineer for Technology and Future Programmes with Rolls-Royce Civil Large Engines to be the new MD seems to me to be very positive news. And importantly an addition that potential investors would welcome.
Quote
Mark Thomas, CEng, FRAeS

Mark is Chief Engineer for Technology and Future Programmes in the Rolls-Royce Civil Large Engines Business. He leads the Engineering teams responsible for the exploration and concept design of next generation propulsion systems; also the execution of system level demonstrators to deliver innovative technologies meeting future product requirements.

In 2014 Mark will celebrate 25 years with Rolls-Royce, joining the Company in 1989 as a sponsored Undergraduate trainee before completing an Engineering degree at Queens’ College, Cambridge University.

Mark’s career started in the Rolls-Royce Defence Aerospace Business and he has completed a variety of Engineering and Management roles located in the UK and Germany.

Notable roles have included Chief Development Engineer for the EJ200 (Typhoon) Engine, Programme Executive for UK Defence Research and Technology, Chief Engineer for the EJ200 (Typhoon), RB199 (Tornado) & Adour (Hawk/Jaguar) engine programmes, and Technical Director of the Eurojet Turbo GmbH consortium based in Munich.

As a Chief Engineer in Defence, Mark was responsible for the support of around 3,000 engines worldwide with 25 Military Operators ranging from the US Navy to Royal Australian Air Force.

In 2009 Mark moved to the Civil Aerospace Business in Derby to take up the role of Chief Engineer for the Trent 900 (Airbus A380), leading the team during an especially challenging three year period for the programme, working closely with Airbus and Airline Customers.

Mark is a Chartered Engineer, Fellow of the Royal Aeronautical Society and also a Governor of a flourishing Engineering Academy. He mentors a number of engineers in Rolls-Royce and is a key member of the Rolls-Royce Senior Engineering Leadership team.

Mark is married with two teenage sons and one daughter and lives in Leicestershire. Outside work he enjoys skiing, travel and reading.
- See more at: http://aerosociety.com/Events/Event-List/1577/Rolls-Royce-future-developments-in-engine-technology#sthash.Zx2ceu45.dpuf

I think this  answers rather handily the questions of whether REL is a serious concern and whether there is anyone with real experience working there.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/21/2015 12:12 am
I think this  answers rather handily the questions of whether REL is a serious concern and whether there is anyone with real experience working there.
In theory yes, in practice no.  :(

Skeptics will note that no one would walk away from a 25 year career with a company without substantial motivation to do so. 

Doubters will continue to insist that only a full size flight vehicle returning from orbit, having deployed a full size payload, will adequately demonstrate that it can work.

Then they will (grudgingly) admit it works but insist that that REL will never sell any.  :(

I'll note that substantial investors in new companies often require Board level representation as a condition of that investment.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 03/21/2015 01:02 pm
I think this  answers rather handily the questions of whether REL is a serious concern and whether there is anyone with real experience working there.
In theory yes, in practice no.  :(

Skeptics will note that no one would walk away from a 25 year career with a company without substantial motivation to do so.

They can't question the experience though.

Another interesting possibility struck me: I used to work for a big Finnish phone maker and when a fairly high up executive arrived from a competitor to become CEO it was a prelude to a takeover.  ..... :-)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 03/21/2015 01:41 pm
When someone with the credentials of Mark Thomas comes in from a company as important as RR then there's something serious afoot.

It's not clear if he's maintaining a position at RR?  If he still maintains some position at RR then that has implications for what's going on with regards the latest announcement. As suggested above, perhaps there's going to be a take-over or collaboration of some sort.

If he's severing his ties with RR then that also tells us something. He will have had a look at all the insider information before he makes a career move like that. He won't want to tarnish his reputation and get on-board with a project that he thinks won't succeed.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 03/21/2015 03:45 pm
I think this  answers rather handily the questions of whether REL is a serious concern and whether there is anyone with real experience working there.
In theory yes, in practice no.  :(

Skeptics will note that no one would walk away from a 25 year career with a company without substantial motivation to do so.

They can't question the experience though.

Another interesting possibility struck me: I used to work for a big Finnish phone maker and when a fairly high up executive arrived from a competitor to become CEO it was a prelude to a takeover.  ..... :-)

I used to think RR might take REL over at some point, but now I just wonder why they haven't already.
Given the number of ex RR employees at REL from the top down it's effectively a RR spinoff anyway.
At this point in time REL has basically proved their major engine innovation and everything to come over the next 3-4 years is engine integration work that could benefit greatly from the massive resources of RR as well as RR's great experience negotiating ITAR and being a major US defence contractor. I'm sure REL's IP could be worth many the cost of the company to RR when applied across RR's product line.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 03/21/2015 06:47 pm

I think this  answers rather handily the questions of whether REL is a serious concern and whether there is anyone with real experience working there.
In theory yes, in practice no.  :(

Skeptics will note that no one would walk away from a 25 year career with a company without substantial motivation to do so.

They can't question the experience though.

Another interesting possibility struck me: I used to work for a big Finnish phone maker and when a fairly high up executive arrived from a competitor to become CEO it was a prelude to a takeover.  ..... :-)

I used to think RR might take REL over at some point, but now I just wonder why they haven't already.
Given the number of ex RR employees at REL from the top down it's effectively a RR spinoff anyway.
At this point in time REL has basically proved their major engine innovation and everything to come over the next 3-4 years is engine integration work that could benefit greatly from the massive resources of RR as well as RR's great experience negotiating ITAR and being a major US defence contractor. I'm sure REL's IP could be worth many the cost of the company to RR when applied across RR's product line.

Be interesting to see if a takeover by RR is in the offing, I'm almost surprised this hasn't already happened. Perhaps they are waiting for the AFRL to report back to find out if there is the possibility of a valuable future customer for the technology.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 03/21/2015 08:39 pm


I used to think RR might take REL over at some point, but now I just wonder why they haven't already.
.....

Be interesting to see if a takeover by RR is in the offing, I'm almost surprised this hasn't already happened. Perhaps they are waiting for the AFRL to report back to find out if there is the possibility of a valuable future customer for the technology.
....

I have no expertise to base this on but it would surprise me a bit given the immensely competitive market that RR are in.  It seems to me like a fight to the death against superb competitors with possibly better subsidies. If I was them I'd want to spend every ounce of my R&D effort on getting some advantage in the current jet engine battles.   I've heard speculation that RR might even be concerned that SABRE would divert talent away that it needs.  This could be an example.

I went to a lecture not long ago about RR research areas and it spent a lot of time on the Ultrafan and an explanation of the market and how it works - engines sold before they are even designed.  To me it sounded like the sort of fierce competition that tends to make people focus on improving widget X instead of inventing totally new ones and hoping to sell them - simply because any loss, any mistake could hand billions of dollars of future revenue to a competitor.

Their long term worries, according to the speaker (John Whurr), are that distributed propulsion will make it more sensible for the airframer to also build the engines, since they will be so intricately integrated, and that there wont' be the option of buying from a range of engine manufacturers.  i.e. that their raison d'etre will disappear.

So SABRE seems like rather a diversion to me.....but.... he did mention that they do some degree research into cryogenic engines, hydrogen as a fuel (my terminology is probably all wrong).  Anyhow I pricked my ears up because that sounded a little like SABRE.

To me it seems more logical that RR might have an interest in using precoolers for engines other than SABRE. It would certainly be a trick that others might find hard to copy.

I have no special knowledge.  I'm speculating - which is more fun the less one actually knows :-).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/22/2015 08:45 am
Their long term worries, according to the speaker (John Whurr), are that distributed propulsion will make it more sensible for the airframer to also build the engines, since they will be so intricately integrated, and that there wont' be the option of buying from a range of engine manufacturers.  i.e. that their raison d'etre will disappear.
"Distributed propulsion"

http://en.wikipedia.org/wiki/Distributed_propulsion

What specifically did he mean by the term?
Quote
So SABRE seems like rather a diversion to me.....but.... he did mention that they do some degree research into cryogenic engines, hydrogen as a fuel (my terminology is probably all wrong).  Anyhow I pricked my ears up because that sounded a little like SABRE.

To me it seems more logical that RR might have an interest in using precoolers for engines other than SABRE. It would certainly be a trick that others might find hard to copy.
Then you'd be talking about REL's work on the EU funded LAPCAT project for M5 airliners.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 03/22/2015 01:10 pm
Their long term worries, according to the speaker (John Whurr), are that distributed propulsion will make it more sensible for the airframer to also build the engines, since they will be so intricately integrated, and that there wont' be the option of buying from a range of engine manufacturers.  i.e. that their raison d'etre will disappear.
"Distributed propulsion"

http://en.wikipedia.org/wiki/Distributed_propulsion

What specifically did he mean by the term?

As I understood him, it meant all sorts of combinations of propulsors, engines and batteries ranging from engines with mechanical transmission to their distributed propulsors to fully electric aircraft with lots of battery storage.

RR has to study these to see if there's a place for it in any of them and to know when and what moves to make (my interpretation).



So SABRE seems like rather a diversion to me.....but.... he did mention that they do some degree research into cryogenic engines, hydrogen as a fuel (my terminology is probably all wrong).  Anyhow I pricked my ears up because that sounded a little like SABRE.

To me it seems more logical that RR might have an interest in using precoolers for engines other than SABRE. It would certainly be a trick that others might find hard to copy.
Then you'd be talking about REL's work on the EU funded LAPCAT project for M5 airliners.

I found this quote from a Reaction Engines Q&A on "The Engineer"'s website:  http://www.theengineer.co.uk/aerospace/in-depth/skylon-and-sabre-your-questions-answered/1014164.article

Quote
Other market applications for the technologies that we have been developing include but are not limited to improving the efficiency of ground-based heat engine cycles for power production, reducing infra-red signatures in engine exhausts, increasing the performance of automotive engines through improved waste heat recovery, higher performing air-conditioning and refrigeration systems for civil and industrial applications such as for LPG shipping, and increasing the efficiency of cooling for electrical and nuclear power systems.

So I can imagine those precoolers being of interest e.g. to the Trident "successor" submarines or possibly to the company that RR invested in which wants to make small modular nuclear reactors for civil applications - so you don't have  such a huge capital cost before you can start generating - you can grow bit by bit and upgrade bit by bit too.  You can also obviously see the interest for LO aircraft - like FCAS.  etc etc.  It seems odd that something could help the efficiency of ground based automotive engines but have no value to aircraft engines at all, at least in theory if weight was not a problem and cost could be reduced.  So I am wondering if Mach 5 Lapcat isn't a sort of distraction from some other more conventional use for precoolers?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 03/22/2015 09:15 pm
Mark Thomas is an experience guy.

It will be interesting to see if he makes any big changes, like you know hire a PR person that writes regular updates about the project :P

I never really heard anything from Rolls Royce that they are looking to make a major entry into a new market and the acquisition of REL would be a major move for them But it they are losing talent to REL, RR is probably looking at their options.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/24/2015 09:24 am
As I understood him, it meant all sorts of combinations of propulsors, engines and batteries ranging from engines with mechanical transmission to their distributed propulsors to fully electric aircraft with lots of battery storage.
RR provide a lot of the small lift jet engine for various VTOL concepts in the 1960s.

In the end only the Harrier entered service. Given Boeing couldn't even face the idea of a blended wing body airliner for the 787 this is decades away at least.
Quote
It seems odd that something could help the efficiency of ground based automotive engines but have no value to aircraft engines at all, at least in theory if weight was not a problem and cost could be reduced. 
What REL have been saying is that this tech is very difficult to retrofit to existing jet engines as they were built to use (and need) certain flows, pressures and temperatures. Pre coolers can change the game if built into a new design from day one.
Quote
So I am wondering if Mach 5 Lapcat isn't a sort of distraction from some other more conventional use for precoolers?
When someone puts cash on the table to investigate a long term idea versus various ideas that have put no money on the table it's never a distraction. :(

BTW while a real M5 airliner is probably decades away that programme let REL investigate contra rotating turbines (now SOP on the larger Trents but when this started only seen on the Olympus used in the Harrier) and low NOx combustion which is expected to create 1% of the NOx of other H2 combustors.

Useful things to have in the too box if you're planning to build a big low weight LH2 engine.  :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: topsphere on 03/25/2015 12:01 pm
I'm going to a talk entitled "Precooled propulsion – key to 21st century spaceflight" by Richard Varvill of REL tomorrow. I will try and either record audio or make notes to post here, but does anyone have any burning questions that I might attempt to put to him?

Edit - Just realised tomorrows talk will be broadcast live - http://www.develop3dlive.com/d3d-live-stream-gmt/   - starting at ~14:20 GMT

I'll still try and make notes but if people want to better understand what Mr Varvill will be saying it may be better to watch his talk.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 03/25/2015 01:55 pm
I'm going to a talk entitled "Precooled propulsion – key to 21st century spaceflight" by Richard Varvill of REL tomorrow. I will try and either record audio or make notes to post here, but does anyone have any burning questions that I might attempt to put to him?

Off the top of my head these are my questions:
 
   1) Does the SABRE 4 cycle use hydrogen recycling to achieve it's high efficiency? (He wont answer but may have a tell that gives it away)

  2) Does the SABRE frost prevention work by turning off precooler module pairs in a rotational cycle around the      precooler allowing the channels to be constantly blown clear? (ditto)

  3)Has the SABRE 4 been definitively chosen as the production engine yet?

  4)Will the final production model be a Skylon E type?

  5)What does he think of the UK Spaceport shortlist and whether he thinks it's important that the selected site be   capable of being expanded to support orbital vehicles in the long term, such as Skylon, or is it more important to be close to the  existing aerospace economic base?

  6)Would REL every consider a buy out from Rolls Royce?

  7)What's the status of Valkyrie, the nacelle test vehicle et al?   

  8)Has the USAF CRADA experience been a positive one given REL's justified fear of ITAR entanglement?

  9)Roughly what percentage of future Skylon production will take place in the UK, i.e. parts production, assembly, etc?

  10)The city of London has a reputation for being poor at financing long term infrastructure projects, has REL found that problem  in relation to Skylon?


Most of these questions probably aren't very answerable though.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 03/28/2015 09:51 pm
Going back to Mark Thomas, Rolls Royce and the possibility of other light weight heat exchanger applications, in look into Thomas I found this presentation:

http://aerosociety.com/Assets/Docs/Events/746/GBD_Propulsion_211014_RR_1.pdf

Which led to this one:

http://www.newac.eu/uploads/media/NEWAC_Technologies.pdf

Where the introduction of a heat exchanger between bypass air and compressed air situated between the low pressure and high pressure compressors is used to gain a higher overall pressure ratio. The heat exchanger used is a titanium corrugated lattice but it would be interesting to know how its efficiency compares to SABRE's precooler.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/29/2015 09:56 am
I'm going to a talk entitled "Precooled propulsion – key to 21st century spaceflight" by Richard Varvill of REL tomorrow. I will try and either record audio or make notes to post here, but does anyone have any burning questions that I might attempt to put to him?

Edit - Just realised tomorrows talk will be broadcast live - http://www.develop3dlive.com/d3d-live-stream-gmt/   - starting at ~14:20 GMT

I'll still try and make notes but if people want to better understand what Mr Varvill will be saying it may be better to watch his talk.
This looks interesting but I missed it.

Is there any idea when they will post this years videos?

Failing that can you give a brief outline of key points?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 04/01/2015 12:32 pm
Re Richard Varville's talk at Develop3D.  I asked them on their Facebook page about the video and they answered:
Quote
Develop3D Yep, all the videos from #D3DLive will be posted online soon. Stay tuned for the release announcement in the coming weeks
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/01/2015 01:28 pm
Re Richard Varville's talk at Develop3D.  I asked them on their Facebook page about the video and they answered:
Quote
Develop3D Yep, all the videos from #D3DLive will be posted online soon. Stay tuned for the release announcement in the coming weeks
I'll have to look out for that.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: topsphere on 04/01/2015 01:58 pm
I'm going to a talk entitled "Precooled propulsion – key to 21st century spaceflight" by Richard Varvill of REL tomorrow. I will try and either record audio or make notes to post here, but does anyone have any burning questions that I might attempt to put to him?

Edit - Just realised tomorrows talk will be broadcast live - http://www.develop3dlive.com/d3d-live-stream-gmt/   - starting at ~14:20 GMT

I'll still try and make notes but if people want to better understand what Mr Varvill will be saying it may be better to watch his talk.
This looks interesting but I missed it.

Is there any idea when they will post this years videos?

Failing that can you give a brief outline of key points?

I'm afraid I forgot to bring a pen and paper :(

It was a good talk, nothing that seemed a new revelation, but then I haven't been following the technical development too closely.

He started off very generally, talking about justifying re-use vs expendable, background and history (HOTOL/work at rolls-royce), then background of skylon, went into quite a bit of detail about the mechanics of the SABRE engine, then current status of REL and future applications.

I'll leave you to pass judgement until you've seen the video, though.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/02/2015 09:32 am
I'm afraid I forgot to bring a pen and paper :(
Not a problem. We'll wait for the videos.
Quote
It was a good talk, nothing that seemed a new revelation, but then I haven't been following the technical development too closely.

He started off very generally, talking about justifying re-use vs expendable, background and history (HOTOL/work at rolls-royce), then background of skylon, went into quite a bit of detail about the mechanics of the SABRE engine, then current status of REL and future applications.

I'll leave you to pass judgement until you've seen the video, though.
It's the current status part that's likely to change over time.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 04/03/2015 06:14 am
Below are some thoughts on Skylon areodynamics, and safety. I could be making some incorrect assumptions here, so am happy to hear corrections.

Much has been made of how the Skylon aerodynamics are much improved over HOTOL due to the new airframe configuration: it now requires much less trim even as the fuel tanks empty and it transitions to rocket power.

That’s a welcome advance, but it seems to me that re-entry could still be challenging for a Skylon shape - at least more challenging than with capsules. I certainly believe that when flying during ascent it will be stable and easy to trim - those canards are far forward of the center of mass & pressure and so up to the task.

But the early stages of atmospheric entry are not at all like climbing, winged flight. With the nose high, the wings are essentially drag devices, and inasmuch as Skylon is an aircraft it’s in a free-fall stall. Unlike a capsule, the Skylon shape is complex and extends far away from the center of lift, so any net forces from the extremities are on long moment arms and need to be dealt with. And unlike a capsule it will not be passively stable. That said, my guess is that Skylon must be actively ‘flown' on the canards during re-entry in the period when the atmosphere overpowers the RCS, and before Skylon is flying forwards - on wings like an aircraft.

The Skylon images indicate that there are elevons on the wings, but during high-alpha entry they seem close to the center of lift and so would not offer as much leverage as the canards (or the equivalent body flap at the rear of the space shuttle orbiter).

If I’m right, failure of the canard actuator would be disastrous. I don't believe a thin movable aero surface like that has been flown from orbital speed through entry heating, and to sea level - the most recent public documents on Skylon state that the canards will need to be actively cooled.

I'm sure the cooling mechanism and the actuators will be expertly designed, but with a spacecraft that's expected to fly many times, we can worry about what happens when statistically unlikely events occur. I’d love to hear how REL would respond to questions about cooling mechanism and/or actuation mechanism failures.

----------------------------------

Since we’re not likely to hear from REL on these things, let’s do some speculating:

+ The canards could be designed to require active cooling under normal conditions, but survive (need replacement) if it fails.
+ A second redundant pair of canards could be added to the rear of the fuselage, i.e. a tailplane/horizontal stabilizer.

If you were to add those additional aerosurfaces you get some other benefits too. It would give greater control authority which could conceivably help the self-ferry case on shorter runways: the additional surfaces would allow the nose to be pulled up earlier, putting more air under the wings leading to an earlier take-off. Similarly, all four surfaces could serve as air-brakes after landing, reducing roll-out distance.

And while we’re talking about self-ferry, if the engines could be gimbaled above the horizon, that too would help pick up the nose as the engines are behind the landing gear. I suppose it would also mean less rocket blast hits the runway which is a good thing.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 04/04/2015 04:00 pm
Re the need to cool the canards:

It turns out BOR-4 used a vapor cooling system - a passive one - for its fins:

Quote
The structure of the heat shield of the wings was different from the remainder of the body. Indeed, because of the aerodynamic profile of the lifting body the wings were thin and could not support the heavy tiles. The interior cavity of wing was filled by a porous matter (the same as felt which holds the tiles on the fuselage) and impregnated with a special composition based on water. Thus, the vapor was used for cooling the structure during the intense heating on the return trajectory.
From: http://www.buran-energia.com/bor/bor-desc.php

So something like that could be used for Skylon. Obviously the advantage of a passive system is you don't need to worry about what happens when the coolant circulation system fails.

And perhaps you could do both: an active system that, when failed, leaves enough residual vapor/transpiration capacity to survive one entry?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/04/2015 11:36 pm
Re the need to cool the canards:

It turns out BOR-4 used a vapor cooling system - a passive one - for its fins:
So something like that could be used for Skylon. Obviously the advantage of a passive system is you don't need to worry about what happens when the coolant circulation system fails.

And perhaps you could do both: an active system that, when failed, leaves enough residual vapor/transpiration capacity to survive one entry?
REL probably chose water cooling over something like heat pipes because the system has been flight tested at least once.

There is a declasified test report for a warehead test in the late 70s or early 80s on DTIC about it. Since it was a warhead design the structure was "thin" as they don't aim to decellerate much before detonation.

People call this "active" cooling but there is typically no actual "pump" involved. It's just water being allowed to boil and heat out of the surfaces.

RCC is good to 3000c in vacuum. it's likely to be SiC coated, like the Shuttle nose and leading edge sections, so good to somewhere like 1500 to 1800c without cooling.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Space OurSoul on 04/06/2015 04:24 pm
the additional surfaces would allow the nose to be pulled up earlier, putting more air under the wings leading to an earlier take-off. Similarly, all four surfaces could serve as air-brakes after landing, reducing roll-out distance.

And while we’re talking about self-ferry, if the engines could be gimbaled above the horizon, that too would help pick up the nose as the engines are behind the landing gear. I suppose it would also mean less rocket blast hits the runway which is a good thing.

Early rotation: Once you're out of ground effect, I think the design would already be at optimal angle-of-attack for the take-off airspeed regime.

High gimbal: That would represent a new stress dynamic for transmitting thrust to the airframe: Now a shear on the engine itself and a torque on the wings. So a bigger mass penalty in the structure? And air is a capricious thing: I think you'd still want thrust running through the center-of-mass or who knows what-all instabilities you'd run into in the turbulent lower atmosphere (where, granted, aero surfaces are good at helping (although less so at low airspeeds)).

The effect of either approach is to trade higher drag for increased lift. I'm not sure that lift is the right variable to optimize for: I would have thought that optimizing for early acceleration (i.e _lower_ drag) would actually be what you want. (The way I though of it, probably simplistically, is that if you had high lift but traded a lot of fuel to get it, all you'd end up with would be a slightly less-fueled ship a few meters higher off the ground, going at the same speed. All your fuel's energy went into adding turbulence to the atmosphere.)

But I realize that it's a very complicated optimization problem: Less time on the runway may well translate to mass savings in the undercarriage, less brake-cooling water to carry, etc. And if you really can get into ground-effect flight earlier, it might be a very efficient regime in which to accelerate.


A few threads back I floated the notion of dorsal re-entry. Imagine a configuration like SR-71 with two vertical stabilizers, one at each wingtip and no canard. It rolls down the runway "upside-down" with the stabilizers doubling as undercarriage. The payload doors are underneath at this time, and the top is unbroken TPS out of FOD danger from objects on the runway. During re-entry, the ship lies on its back, stabilizers sticking up out of the heating. It then flips over, probably subsonic, and lands like it takes off.
The relevance to the current discussion is that you now have two configurations (albeit, obviously, tightly linked!) that can be optimized: the take-off can favor low-speed aerodynamics, and the re-entry can favor dynamic stability.
While this approach might help for roll stability, I'll admit it doesn't much address the point that you raised which I think was focused on pitch. It does seem like some kind of aero-surface, ideally far from the center of lift, would help for that flight regime you mentioned.

 

All these thoughts make me realize, yet again, what a difficult optimization problem Skylon represents. I wonder if REL ever had a bash at "genetic" programming: iterating randomly tweaked designs, simulate over the whole mission, repeat.

But I talk too much.
</uninformed guesses>
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/06/2015 10:29 pm
All these thoughts make me realize, yet again, what a difficult optimization problem Skylon represents. I wonder if REL ever had a bash at "genetic" programming: iterating randomly tweaked designs, simulate over the whole mission, repeat.
This is the challenge to building Skylon. Any changes you make to improve some part of the trajectory have to either improve the whole of the trajectory or leave the rest unaffected.

Once you realize this you realize just how tricky it is to make changes to the design and how carefully the REL team have had to think this through.

In one of the periodic update reports REL have submitted to IAC they mentioned the use of Monte Carlo simulation methods to refine the design.

The upside is this task is still simpler than the various attempts at SCramjet powered vehicles that incorporate the inlet into the front of the vehicle.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Asteroza on 04/06/2015 11:38 pm
Using the dorsal surface as the heatshield has merits, but necessitates the "barrel roll of death", as opposed to the "swoop of death" required for nose first reentry VTVL SSTO's. I think an unbroken TPS is preferable, and makes certain other things (beamed thermal propulsion receiver) easier to integrate into the airframe. Ventral opening payload bay also allows easy payload load/unload via a scissor lift cargo transfer vehicle/pit, as opposed to a gantry crane. The kicker is payloads and airframe have to handle long durations in both flipped and unflipped flight modes, which makes systems design more complicated. I suppose doing the flip always clockwise, and the unflip counterclockwise, might make it a bit easier, especially with a passenger module and the rotating seat frames.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/07/2015 05:00 pm
Below are some thoughts on Skylon areodynamics, and safety. I could be making some incorrect assumptions here, so am happy to hear corrections.

Much has been made of how the Skylon aerodynamics are much improved over HOTOL due to the new airframe configuration: it now requires much less trim even as the fuel tanks empty and it transitions to rocket power.
I've read your posts a few more times and I'm still not clear what  you're worried about. Is it a pitch failure? Is it a roll failure?

BTW The Shuttle control system also had a period its control surfaces were not fully effective and RCS thrusters were used together with the aero surfaces. Later development programmes found ways to make more effective use of the control surfaces (differential use of the 2 section rudder IIRC) that reduced RCS propellant usage substantially. [EDIT Point is this is not a new phenomena and has been dealt with before. Skylon's maximum nose up would also be about 20deg below Shuttles peak (50deg Vs 70deg). I'm quite sure that REL have flown Skylon through many simulated trajectories to check what happens in these cases ]

BTW it's SOP to have triply redundant actuators for large aircraft. You're postulating simultaneous failure of all drive loops and a possible cooling failure as well.

Probaballistic risk assessment would suggest that failure mode is very remote, but I don't have stats for the simultaneous failure of all flying controls on large aircraft to give a number.  I can say the goal for blind landing systems was 1 failure in every billion operating hours across all aircraft it was installed in and AFAIK it was achieved.

Using the dorsal surface as the heatshield has merits, but necessitates the "barrel roll of death", as opposed to the "swoop of death" required for nose first reentry VTVL SSTO's.
Or you could stick with Skylon's planned flight path and avoid either.   :)
Quote
I think an unbroken TPS is preferable, and makes certain other things (beamed thermal propulsion receiver) easier to integrate into the airframe.
The trouble is it relies on the whole surface remaining perfect for all missions.

That's simply unreasonable for a vehicle of this size and expected life time.   :( [EDIT NASA are doing it for Orion, SpaceX are not doing it for Dragon, and Dragon is planned to be reused ]
Quote
The kicker is payloads and airframe have to handle long durations in both flipped and unflipped flight modes, which makes systems design more complicated.
Very much more complicated.
Quote
I suppose doing the flip always clockwise, and the unflip counterclockwise, might make it a bit easier, especially with a passenger module and the rotating seat frames.
Doubtful. You're back with the making-the-structure-strong-in-2-axes-at-once issue.  :(

When people think of cranes around rockets I believe they are thinking of Saturn/Apollo (or SRB's) being assembled in a building so big it has its own weather.

But a Skylon hangar is more like a 3-4 storey building with 20 tonne gantry crane. This is far below the leading edge of crane technology. I'd expect 10s of suppliers globally could deliver such a system.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 04/07/2015 05:32 pm
My point (worry) could be summarized like this:

Skeptical assessments of Skylon tend to focus on it having 'holy grail' SSTO performance, and using unproven SABRE engines. But its return from orbit is also novel/unproven in terms of its shape and size. This part of the design challenge is rarely highlighted.

But just as with the SABRE engines, Skylon re-entry does not require any magical new technology (and it evidently didn't phase the ESA assessors) but it is a novel shape, and its development will involve more than just selecting high temperature materials and nailing them together.

My bet is the development plan will include high-fidelity testing of those canards as they move around in high-temperature >hypersonic air, and fully understanding the way the resultant shock patterns interact with the fuselage. Heating at the hinge seems like a good place to focus on.

The tip of the engine inlet cones are likely another hot-spot too, but modeling/testing that seems trivial compared to the canards.

Speculation: collaboration with US Air Force could provide an opportunity for the sort of testing I'm talking about here.

Edited for clarity.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 04/07/2015 06:16 pm
Re take-off optimization (responding to full quote below):

I find these discussions great fun, but it's worth remembering that any 'winning' argument is probably wrong/incomplete as we're never privy to all the relevant factors.

That said, let me explain more about my thinking.

First of all, I should have emphasized I was talking about improving take-off for the self-ferry case; with little/no LOX and less LH2 on board the loads will be much less than with an orbital launch from its custom runway.

It seems to me highly desirable for Skylon to be able to self-ferry from regular runways, e.g. the Airbus runway in Toulouse (3.5km) to its own 5.5km orbital launch facility. I'm thinking about shortening take-off length in hopes that self-ferry could be made realistic.

In additional to delivering new vehicles, this would mean simplified recovery if it has to land at an alternate site. It would also mean a spare could be flown in - perhaps leased from another provider - if one had maintenance issues.

In terms of take-off aerodynamics, I'm pretty confident my idea (duplicate the canards to get double the lift/control authority) has merit theoretically. First of all, we can be sure that the wing is not optimized for short take off - many factors constrain it in other directions. Even commercial aircraft airfoils are not optimized for take-off, hence the need for high-lift devices such as flaps. The canards would essentially be the equivalent of flaps.

Imagine an extreme case: A Skylon with no canards, and wings much smaller than the current design: they generate so little lift that its still resting on its undercarriage when barreling down its 50km runway at 700mph. But at 700mph there is enough air flowing by to lift the vehicle IF the wings had some angle of attach with respect to the airflow. That's what the canards could do for this case, and that's why I suggested doubling up the canards could shorten the take-off length during self-ferry with the current design.

EDIT: my assumption is that the current canards are not already large enough to provide all the lift you'd require to pick the nose up for the shortest self-ferry take-off, and that duplicating them gives worthwhile redundancy.

And in terms of them causing drag which would hinder short take-off: they'd be feathered (so minimal drag) until they were used to rotate. In that respect, they are better than flaps on commercial aircraft.

the additional surfaces would allow the nose to be pulled up earlier, putting more air under the wings leading to an earlier take-off. Similarly, all four surfaces could serve as air-brakes after landing, reducing roll-out distance.

And while we’re talking about self-ferry, if the engines could be gimbaled above the horizon, that too would help pick up the nose as the engines are behind the landing gear. I suppose it would also mean less rocket blast hits the runway which is a good thing.

Early rotation: Once you're out of ground effect, I think the design would already be at optimal angle-of-attack for the take-off airspeed regime.

High gimbal: That would represent a new stress dynamic for transmitting thrust to the airframe: Now a shear on the engine itself and a torque on the wings. So a bigger mass penalty in the structure? And air is a capricious thing: I think you'd still want thrust running through the center-of-mass or who knows what-all instabilities you'd run into in the turbulent lower atmosphere (where, granted, aero surfaces are good at helping (although less so at low airspeeds)).

The effect of either approach is to trade higher drag for increased lift. I'm not sure that lift is the right variable to optimize for: I would have thought that optimizing for early acceleration (i.e _lower_ drag) would actually be what you want. (The way I though of it, probably simplistically, is that if you had high lift but traded a lot of fuel to get it, all you'd end up with would be a slightly less-fueled ship a few meters higher off the ground, going at the same speed. All your fuel's energy went into adding turbulence to the atmosphere.)

But I realize that it's a very complicated optimization problem: Less time on the runway may well translate to mass savings in the undercarriage, less brake-cooling water to carry, etc. And if you really can get into ground-effect flight earlier, it might be a very efficient regime in which to accelerate.


A few threads back I floated the notion of dorsal re-entry. Imagine a configuration like SR-71 with two vertical stabilizers, one at each wingtip and no canard. It rolls down the runway "upside-down" with the stabilizers doubling as undercarriage. The payload doors are underneath at this time, and the top is unbroken TPS out of FOD danger from objects on the runway. During re-entry, the ship lies on its back, stabilizers sticking up out of the heating. It then flips over, probably subsonic, and lands like it takes off.
The relevance to the current discussion is that you now have two configurations (albeit, obviously, tightly linked!) that can be optimized: the take-off can favor low-speed aerodynamics, and the re-entry can favor dynamic stability.
While this approach might help for roll stability, I'll admit it doesn't much address the point that you raised which I think was focused on pitch. It does seem like some kind of aero-surface, ideally far from the center of lift, would help for that flight regime you mentioned.

 

All these thoughts make me realize, yet again, what a difficult optimization problem Skylon represents. I wonder if REL ever had a bash at "genetic" programming: iterating randomly tweaked designs, simulate over the whole mission, repeat.

But I talk too much.
</uninformed guesses>
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/08/2015 12:13 am
First of all, I should have emphasized I was talking about improving take-off for the self-ferry case; with little/no LOX and less LH2 on board the loads will be much less than with an orbital launch from its custom runway.

It seems to me highly desirable for Skylon to be able to self-ferry from regular runways, e.g. the Airbus runway in Toulouse (3.5km) to its own 5.5km orbital launch facility. I'm thinking about shortening take-off length in hopes that self-ferry could be made realistic.
On self ferry Skylon will be 150 tonnes lighter. That alone will shorten the takeoff substantially. It will accelerate substantially faster and its wing loading be substantially lower. 
Quote
In additional to delivering new vehicles, this would mean simplified recovery if it has to land at an alternate site. It would also mean a spare could be flown in - perhaps leased from another provider - if one had maintenance issues.
REL state the landing speed and sink rate is such that it could land on grass. Note landing, not take off.
Quote
In terms of take-off aerodynamics, I'm pretty confident my idea (duplicate the canards to get double the lift/control authority) has merit theoretically. First of all, we can be sure that the wing is not optimized for short take off - many factors constrain it in other directions.
Nevertheless it will take off in short order in air breathing mode.
Quote
Even commercial aircraft airfoils are not optimized for take-off, hence the need for high-lift devices such as flaps. The canards would essentially be the equivalent of flaps.

Imagine an extreme case: A Skylon with no canards, and wings much smaller than the current design: they generate so little lift that its still resting on its undercarriage when barreling down its 50km runway at 700mph. But at 700mph there is enough air flowing by to lift the vehicle IF the wings had some angle of attach with respect to the airflow. That's what the canards could do for this case, and that's why I suggested doubling up the canards could shorten the take-off length during self-ferry with the current design.

EDIT: my assumption is that the current canards are not already large enough to provide all the lift you'd require to pick the nose up for the shortest self-ferry take-off, and that duplicating them gives worthwhile redundancy.
If they can deliver enough lift to get the nose up for a fully loaded takeoff (which they are sized for) how likely is it they can't when the vehicle is 150 tonnes lighter?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/08/2015 12:13 am

Assessments of Skylon tend to focus on it having 'near impossible' SSTO performance,
For a VTOL SSTO, rather less so for an air breathing HTOL. This matter has been discussed before.
Quote
and using unproven SABRE engines. But its return from orbit is also novel/unproven in terms of its shape, size. And to land in one piece, those canards need to operate as expected.
Exactly like the control surfaces of any vehicle that use aerodynamic lift and exactly as the Shuttle design managed on  135 flights. Like the Shuttle it will probably have triply redundant actuator circuits.

It's the difference between "likely to fail" and "may fail in in 20 000 launches."
Quote
My bet is the development plan includes high-fidelity testing of those canards as they move around in high-temperature >hypersonic air, and fully understanding the way the resultant shock patterns interact with the fuselage. Cooling at the hinge seems like a good place to focus on.
At least part of that has already happened when DLR (who thought the canards too thin to survive the heating) did a major CFD exercise on it using their Tau CFD code and confirmed they will survive.

It's a pretty safe bet that such test work is part of the schedule for the Skylon project.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 04/08/2015 12:43 am
I think you are under the impression that me naming the concerns of Skylon's skeptics, and asking questions means I've already decided Skylon is a flawed concept - and that you need to defend it. Not true.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/08/2015 06:31 am
I think you are under the impression that me naming the concerns of Skylon's skeptics, and asking questions means I've already decided Skylon is a flawed concept - and that you need to defend it. Not true.
Not at all. I'm trying to understand what you're concerned about and you are not making your concerns any clearer.

You started with something about canards being too small then elevons being too close to the body and come up with a reason for having a more conventional tail. You talk about the canard actuators failing but seem to ignore they will likely be triply redundant and when this is mentioned you just seem to ignore it.

So what is the root cause of your worry?



Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 04/08/2015 03:38 pm
I'm not worried; at least not in the usual negative sense. I think I need to put more smileys in my posts because the 'worries' you see are born of an interest and enthusiasm with the engineering challenges Skylon represents. That's clearly not coming through.

If you reread my posts you'll see they go like this (with positive fanboi vibe now added in):

1] "Hey fellow-Skylon fans, I just realized that Skylon's re-entry will push the state of the art further forward than anything before it. How come no-one ever mentions that? More than any spacecraft before it, Skylon actually 'flies' in on the canards. How cool. Passively stable re-entry vehicles are for wimps. :-)"

2] "Wouldn't it be awesome if Skylon could take-off and land at regular airports? I know our friends at REL have already worked out how to make it take off in the shortest distance, but I'm just such a fan that I can't help but think about ways to improve Skylon. So, how about adding canards at the back to aid in earlier rotation. Probably a silly idea, I know."

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/09/2015 12:49 pm

If you reread my posts you'll see they go like this (with positive fanboi vibe now added in):

1] "Hey fellow-Skylon fans, I just realized that Skylon's re-entry will push the state of the art further forward than anything before it. How come no-one ever mentions that? More than any spacecraft before it, Skylon actually 'flies' in on the canards. How cool. Passively stable re-entry vehicles are for wimps. :-)"
Perhaps because no spaceplane before it had cannards? The importance of trim was one of the big discoveries of the HOTOL project. Putting the engines on the wing tips is a big change. Skylon is designed to avoid the continuous "fluttering" of control surfaces the Shuttle used to keep it stable. You're assuming it will be unstable. That's not a given.

An interesting question is could it be stable enough to allow a human pilot to fly it without a computer in the loop to stabilize it.

That would make it a very exciting prospect for some potential customers.

Quote

2] "Wouldn't it be awesome if Skylon could take-off and land at regular airports? I know our friends at REL have already worked out how to make it take off in the shortest distance, but I'm just such a fan that I can't help but think about ways to improve Skylon. So, how about adding canards at the back to aid in earlier rotation. Probably a silly idea, I know."
Then you're missing the biggest issue of all. The huge noise level. It's not just the thrust it's the exhaust velocity for air/H2 is much higher than air/kerosene mixture. While OK for occasional takeoffs or emergency landings (which will be unpowered) it's most unlikley there will be fully fueled take offs from any regular airport.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 04/09/2015 03:21 pm

If you reread my posts you'll see they go like this (with positive fanboi vibe now added in):

1] "Hey fellow-Skylon fans, I just realized that Skylon's re-entry will push the state of the art further forward than anything before it. How come no-one ever mentions that? More than any spacecraft before it, Skylon actually 'flies' in on the canards. How cool. Passively stable re-entry vehicles are for wimps. :-)"
Perhaps because no spaceplane before it had cannards? The importance of trim was one of the big discoveries of the HOTOL project. Putting the engines on the wing tips is a big change. Skylon is designed to avoid the continuous "fluttering" of control surfaces the Shuttle used to keep it stable. You're assuming it will be unstable. That's not a given.

Rather than repeat myself here, I'll refer interested parties (if there are any) back to my initial post on this subject: http://forum.nasaspaceflight.com/index.php?topic=36826.msg1354087#msg1354087.

If you've read anything that indicates the Skylon shape will be more passively stable than the Shuttle during belly-first entry, I'd be very interested in that reference. As you know, the Shuttle was not stable, and its orientation needed to be active maintained with the body flap and elevons.

EDIT: Perhaps we can agree that placing the engines on the wings makes Skylon more symmetrical than the Shuttle in terms of entry (pre-aerodynamic, ~45 degree nose-up) configuration, which is an advantage. But where the orbiter was a simple, relatively compact double-delta, Skylon is a complex shape, and spindly, meaning ISTM that it will have more pronounced forces at the nose and tail that need to be dealt with.

Quote
An interesting question is could it be stable enough to allow a human pilot to fly it without a computer in the loop to stabilize it.

That would make it a very exciting prospect for some potential customers.

Quote

2] "Wouldn't it be awesome if Skylon could take-off and land at regular airports? I know our friends at REL have already worked out how to make it take off in the shortest distance, but I'm just such a fan that I can't help but think about ways to improve Skylon. So, how about adding canards at the back to aid in earlier rotation. Probably a silly idea, I know."
Then you're missing the biggest issue of all. The huge noise level. It's not just the thrust it's the exhaust velocity for air/H2 is much higher than air/kerosene mixture. While OK for occasional takeoffs or emergency landings (which will be unpowered) it's most unlikley there will be fully fueled take offs from any regular airport.

Right. The cases mentioned in my (non fanboi) post were 1] initial delivery to Korou, and 2] recovery after abort: http://forum.nasaspaceflight.com/index.php?topic=36826.msg1355300#msg1355300. I 'worry' that self-ferry even in these rare, special cases might not be possible. And noise is certainly a factor.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 04/09/2015 05:01 pm
And here's the sort of response I was hoping for:

Response to my initial post:

Quote
"While adding redundant control surfaces (e.g. horizontal stabilizers on the tail) would indeed mean you'd still have those available if the front canards were to fail, wouldn't the failed/stuck surfaces cause you control problems that your remaining surfaces might not be able to overcome?"

Me:

"You're probably right. Better to put extra effort into making sure the canards always work. (And are sized for self-ferry in addition to orbital take-off)."
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/10/2015 07:43 am
Rather than repeat myself here, I'll refer interested parties (if there are any) back to my initial post on this
If you've read anything that indicates the Skylon shape will be more passively stable than the Shuttle during belly-first entry, I'd be very interested in that reference. As you know, the Shuttle was not stable, and its orientation needed to be active maintained with the body flap and elevons.
I cannot cite a reference. Considering the Shuttles design you had a series of big "point masses" (3 SSMEs, their plumbing and the OMS modules, along with the APUs, their fuel and cooling) in the tail. That puts a big  weight in the tail and you're trying to the Shuttle at 70 degs without flipping it over.

Skylons, engines, and returning payload (if any) are with the wings in the middle. This means that rather than fighting a big (point) tail mass (  you have a relatively light fuselage in 2 parts which are (roughly) the same mass. That means surfaces can be smaller and response times less critical.

BTW the slab sides on the orbiter made for a very bad glider which was very prone to cross winds.
Quote
EDIT: Perhaps we can agree that placing the engines on the wings makes Skylon more symmetrical than the Shuttle in terms of entry (pre-aerodynamic, ~45 degree nose-up) configuration, which is an advantage. But where the orbiter was a simple, relatively compact double-delta, Skylon is a complex shape, and spindly, meaning ISTM that it will have more pronounced forces at the nose and tail that need to be dealt with.
It's not aesthetics, it's putting the biggest masses on or near the longways  centre of mass so they have near zero moment  :( That's important because the centre of pressure is constantly shifting during reentry as you go from M23 to M0.

There was nothing simple about Shuttles shape. Shuttle histories state it took 40-50 000 hrs of wind tunnel time to develop. Part of that was for the cross range requirements of the USAF and I would suspect partly trying to adapt the blunt body aerodynamics developed for war head reentry capsules into a useable form for a winged vehicle, which basically junked the usual rule of thumb for high speed aircraft that thinner wings are always better.
Quote
Right. The cases mentioned in my (non fanboi) post were 1] initial delivery to Korou, and 2] recovery after abort: http://forum.nasaspaceflight.com/index.php?topic=36826.msg1355300#msg1355300. I 'worry' that self-ferry even in these rare, special cases might not be possible. And noise is certainly a factor.
In 1 the vehicle will be less than 50% of its GTOW to orbit. There is every reason to think it's takeoff run will be much shorter. Keep in mind 1.5Km of that 5.5Km is solely for emergency stopping of a fully loaded Skylon. I don't know if you could drop the takeoff run and emergency braking distance to 3.5Km but I think it would be close.

2)is more a case of planning for an emergency and the legal issues around them. Clearing airspace for a Skylon on abort then getting it down. Which runway it comes down on would depend on how much is pre programmed into its auto pilot and to what extent it can receive external commands. Getting it back to Kourou would then involve a damage assessment, possible repairs up to engine replacement and refueling with LH2. While different in detail from a conventional aircraft the process would be pretty much the same.

"You're probably right. Better to put extra effort into making sure the canards always work. (And are sized for self-ferry in addition to orbital take-off)."
I guess that's a nice illustration of why it's difficult to do "tone" on the internet.  :(

Can you explain why you think the control surfaces which are sized to control a fully loaded Skylon won't be able to cope with the loads imposed by a vehicle that's 150 tonnes lighter in self ferry and over 200 tonnes lighter during re entry? That seems illogical.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 04/10/2015 11:31 am
Hempsell has already stated on the thread that any ordinary sub-3km runway can launch a self-ferry Skylon.

http://forum.nasaspaceflight.com/index.php?topic=24621.msg987883#msg987883


Also as a reminder there are two lectures coming up this month for those able to attend, on Tuesday 14th with Richard Varvill:

http://aerosociety.com/Events/Event-List/1934/Skylon-and-Sabre-Bringing-Space-Down-to-Earth

and on Wednesday 22nd with Alan Bond:

http://aerosociety.com/Events/Event-List/1686/The-Sabre-Engine

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 04/10/2015 07:36 pm
I'm confident everybody in this conversation is within 10% agreement, so to go on would say more about the hazards of forum-based communication than anything else.

For example, lkm says "Hempsell has already stated on the thread that any ordinary sub-3km runway can launch a self-ferry Skylon". Which should settle the issue, right? But in the cited comment Hempsell actually says the following - in 2012 - "we currently believe believe Skylon would be able to use sub-3 km runways".

I take that to mean it's not a 100% done deal, and so a topic for conversation. But when I raise the topic of self-ferry, and speculate on the usefulness of greater control authority if it turns out to be marginal on shorter runways JohnSmith19 asks me: "why you think the control surfaces which are sized to control a fully loaded Skylon won't be able to cope with the loads imposed by a vehicle that's 150 tonnes lighter in self ferry and over 200 tonnes lighter during re entry? That seems illogical."

Just because I'm interested in the self-ferry case doesn't mean I think it can't be done (and REL are liars). But by the same token, REL said they currently believe it can be done, which means there's a chance it might be tricky. That's what makes me raising the issue legit, rather than 'illogical'.

Same thing with Skylon entry. Just because I note that it's rarely talked about - and will not be a walk in the park - doesn't mean that I think it's impossible. But neither do I think it's established that no further work is necessary.

___

To conclude: I don't think anyone here is saying that self-ferry and entry 1] require no further design and testing, or 2] will clearly fail as designed. If you are, then let's continue, otherwise let's change the subject.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 04/10/2015 09:11 pm
I'm confident everybody in this conversation is within 10% agreement, so to go on would say more about the hazards of forum-based communication than anything else.

For example, lkm says "Hempsell has already stated on the thread that any ordinary sub-3km runway can launch a self-ferry Skylon". Which should settle the issue, right? But in the cited comment Hempsell actually says the following - in 2012 - "we currently believe believe Skylon would be able to use sub-3 km runways".

I take that to mean it's not a 100% done deal, and so a topic for conversation. But when I raise the topic of self-ferry, and speculate on the usefulness of greater control authority if it turns out to be marginal on shorter runways JohnSmith19 asks me: "why you think the control surfaces which are sized to control a fully loaded Skylon won't be able to cope with the loads imposed by a vehicle that's 150 tonnes lighter in self ferry and over 200 tonnes lighter during re entry? That seems illogical."

Just because I'm interested in the self-ferry case doesn't mean I think it can't be done (and REL are liars). But by the same token, REL said they currently believe it can be done, which means there's a chance it might be tricky. That's what makes me raising the issue legit, rather than 'illogical'.

Same thing with Skylon entry. Just because I note that it's rarely talked about - and will not be a walk in the park - doesn't mean that I think it's impossible. But neither do I think it's established that no further work is necessary.

___

To conclude: I don't think anyone here is saying that self-ferry and entry 1] require no further design and testing, or 2] will clearly fail as designed. If you are, then let's continue, otherwise let's change the subject.

My intention was only to point out that Hempsell had talked about it previously in the thread as it was some time ago and five threads back and I thought it might add to the debate, not end it. My thought on shortening take off requirements was whether optionally payload could be traded for increased take off thrust by augmenting with LOX.

On reentry, obviously nothing about that is easy but Skylon has always struck me as a somewhat prettier version of Faget's DC-3 and as such presumably has a similar reentry profile.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/14/2015 08:34 pm
To conclude: I don't think anyone here is saying that self-ferry and entry 1] require no further design and testing, or 2] will clearly fail as designed. If you are, then let's continue, otherwise let's change the subject.
Certainly.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Mutley on 04/15/2015 07:50 am
Lots more jobs appearing on the Reaction Engines website

http://www.reactionengines.co.uk/careers.html (http://www.reactionengines.co.uk/careers.html)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 04/15/2015 08:01 am
nice! are these new jobs or sobstitutions of people that left?

anyway, SpaceX is so close now. The others cannot afford to to ignore reusability any more. Although I am seriously afraid someone at ESA will fall into the Siren's trap of a "REUSABLE ARIANE 6 BY 202X"........

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/15/2015 08:31 am
Lots more jobs appearing on the Reaction Engines website

http://www.reactionengines.co.uk/careers.html (http://www.reactionengines.co.uk/careers.html)
Yes that's quite a broad range. Note some of them only make sense in the context of a company expecting to grow quite a lot and to a quite substantial size.

nice! are these new jobs or sobstitutions of people that left?

anyway, SpaceX is so close now. The others cannot afford to to ignore reusability any more. Although I am seriously afraid someone at ESA will fall into the Siren's trap of a "REUSABLE ARIANE 6 BY 202X"........
A lot of those roles look new.

"REUSABLE ARIANE 6 BY 202X"........

Hmm.  :( The fact ULA are committing to something may be more relevant. Before SX could be dismissed as just a private company who could do whatever they liked based on the whim of their CEO.

I think REL are still very weary of being a "government" programme (especially if that's an EU) so they have to steer a very tricky course.

SABRE/Skylon remains very high risk relative to the sort of systems Ariane 6 is being described as, although quite what that final shape will be seems to be changing. Are "all solids" still the baseline?

What might be possible would for ESA to say they need a European backup plan funded at some level in case commercial customers remain implacably opposed to an all solid design.

Solids BTW generate much more vibration on the payload and large ones are difficult (impossible?) to shut down.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 04/15/2015 08:53 am
I still wonder whether the UK government, or REL themselves, sent an application for funding at the Commission for the new Juncker fund. This is not public ownership in the classical way... If they didn't, I would at least like to undestand why :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/15/2015 12:35 pm
I still wonder whether the UK government, or REL themselves, sent an application for funding at the Commission for the new Juncker fund. This is not public ownership in the classical way... If they didn't, I would at least like to undestand why :)
Interesting question but from my (very) cursory look at the plan it's target is to stimulate the growth of businesses in Southern Europe, such as Spain and Greece, Italy perhaps.

One of its goals does seem to be increasing investment in higher risk transport infrastructure projects, and Skylon could definitely be described as one of those.  :)

Sadly it seems Britain may be a bit far North for this option to be viable.   :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 04/15/2015 01:45 pm
well, why it is correct that the goal is stimulating investment, the fund will not have a geographic orientation. true, it constitutes an incredible opportunity for southern Europe, but it has been repeatedly stated that projects will be selected solely on the basis of their benefits- even in EU countries which do not financially participate in the fund (even tough financially contributing to the fund allows countries to have a board member and so influencing decisions, which is not bad if you want to get some of the money you put in back into your country). Then again, the fund is done for industrial development..so maybe REL can apply in a few years or so!
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Mutley on 04/15/2015 03:02 pm
http://www.reactionengines.co.uk/press_release.html (http://www.reactionengines.co.uk/press_release.html)

New press release from Reaction Engines

Looks like the USAF agrees with ESA with regards the feasability of the SABRE concept
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 04/15/2015 03:10 pm
http://www.reactionengines.co.uk/press_release.html (http://www.reactionengines.co.uk/press_release.html)

New press release from Reaction Engines

Looks like the USAF agrees with ESA with regards the feasability of the SABRE concept

Hopefully an announcement that may lead to more significant developments. Probably not in the direction of Skylon as I can't see the USAF being that interested in that as a concept, but perhaps in other areas of in atmosphere vehicle development.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 04/15/2015 03:45 pm
"Reaction Engines Ltd. and AFRL are now formulating plans for continued collaboration on the SABRE engine; the proposed work will include investigation of vehicle concepts based on a SABRE derived propulsion system, testing of SABRE engine components and exploration of defence applications for Reaction Engines’ heat exchanger technologies."


very big deals coming. The first listed is (I believe) wha the AFRL is truly interested in- SKYLON might not be suitable for defense purposes, but other "vehicle concepts based on a SABRE derived propulsion system" might surely be.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 04/15/2015 03:49 pm
http://www.reactionengines.co.uk/press_release.html (http://www.reactionengines.co.uk/press_release.html)

New press release from Reaction Engines

Looks like the USAF agrees with ESA with regards the feasibility of the SABRE concept

No, feasibility is the wrong word.  AFRL "investigations examined the thermodynamic cycle of the SABRE concept and found no significant barrier to its theoretical viability provided the engine component and integration challenges are met."

They found that it can happen but have not ruled on that it will happen.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 04/15/2015 03:53 pm

http://www.reactionengines.co.uk/press_release.html (http://www.reactionengines.co.uk/press_release.html)

New press release from Reaction Engines

Looks like the USAF agrees with ESA with regards the feasibility of the SABRE concept

No, feasibility is the wrong word.  AFRL "investigations examined the thermodynamic cycle of the SABRE concept and found no significant barrier to its theoretical viability provided the engine component and integration challenges are met."

They found that it can happen but have not ruled on that it will happen.

But if anyone has the funds to make it happen it's the USAF, they are the kind of customer REL need.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Oli on 04/15/2015 03:53 pm
http://www.reactionengines.co.uk/press_release.html (http://www.reactionengines.co.uk/press_release.html)

New press release from Reaction Engines

Looks like the USAF agrees with ESA with regards the feasability of the SABRE concept

From the press release:

Quote
"Although application of the SABRE for single stage to orbit space access remains technically very risky as a first application, the SABRE may provide some unique advantages in more manageable two stage to orbit configurations."

Given the huge projected development cost of the SSTO version, I kind of agree with that.

They could, for example, leave the atmosphere at lower speed, in order to reduce aerodynamic pressure, and reenter at Mach 15 or so instead of orbital speed. The vehicle would then land downrange similar to the Hopper concept and could be towed back to Kourou.

An upper stage with Vinci could do the rest. It would probably fit into the vehicle (with a longer bay obviously).

Any other ideas?


Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 04/15/2015 04:07 pm

http://www.reactionengines.co.uk/press_release.html (http://www.reactionengines.co.uk/press_release.html)

New press release from Reaction Engines

Looks like the USAF agrees with ESA with regards the feasability of the SABRE concept

From the press release:

Quote
"Although application of the SABRE for single stage to orbit space access remains technically very risky as a first application, the SABRE may provide some unique advantages in more manageable two stage to orbit configurations."

Given the huge projected development cost of the SSTO version, I kind of agree with that.

They could, for example, leave the atmosphere at lower speed, in order to reduce aerodynamic pressure, and reenter at Mach 15 or so instead of orbital speed. The vehicle would then land downrange similar to the Hopper concept and could be towed back to Kourou.

An upper stage with Vinci could do the rest. It would probably fit into the vehicle (with a longer bay obviously).

Any other ideas?

Couldn't they have a smaller parasite hypersonic vehicle for access to orbit carried on the back of a larger slower carrier craft.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Oli on 04/15/2015 04:21 pm
Couldn't they have a smaller parasite hypersonic vehicle for access to orbit carried on the back of a larger slower carrier craft.

That would mean you have to design 3 vehicles: The carrier aircraft, the parasite and the carrier + parasite combined.

IMO the long term goal should remain SSTO, but with an intermediate step (and expendable upper stage).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Lars-J on 04/15/2015 06:05 pm
http://www.reactionengines.co.uk/press_release.html (http://www.reactionengines.co.uk/press_release.html)

New press release from Reaction Engines

Looks like the USAF agrees with ESA with regards the feasability of the SABRE concept

From the press release:

Quote
"Although application of the SABRE for single stage to orbit space access remains technically very risky as a first application, the SABRE may provide some unique advantages in more manageable two stage to orbit configurations."

Given the huge projected development cost of the SSTO version, I kind of agree with that.

Many of us has argued that from the start. But some staunch Skylon supporters (like John Smith 19) think it has to be SSTO or nothing. The logic of that escapes me, but then again they also seem to find smaller versions of Skylon (to test technology) to be a waste of time. Skylon needs to be a massive SSTO, apparently.   

Boeing didn't start out by building 747's. The 747 wasn't even their first jet aircraft.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 04/15/2015 06:41 pm
TSTO vs. SSTO Skylon is a complex issue. Factors I've come to consider important are:

1] The recent discussions highlighting the difficulty of upper stage re-use. It's a reasonable guess that TSTO Skylon would be cheaper to develop and less likely to fail, but will be more costly to run (i.e. you throw away the US each time). Pick your poison.

2] Size might not matter as much as you'd think. A few pages back I became convinced that a smaller Skylon might not be easier/cheaper to build.

3] If SpaceX manages to perfect stage one recovery, then a TSTO Skylon - that just achieves the same result and no more - is not going to happen.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 04/15/2015 06:47 pm
I'm not sure why there is so much focus as regards this announcement on orbital vehicles as it's far more likely this will see use at least initially in some kind of hypersonic aircraft. That's where the USAF's future focus is not exotic space vehicles.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 04/15/2015 07:05 pm
Agreed that USAF is probably not looking to SABRE for just orbital launch, but in the press release, Barry Hellman (USAF Program Manager) weighs in on the SSTO/TSTO topic by saying:

Quote
"Although application of the SABRE for single stage to orbit space access remains technically very risky as a first application, the SABRE may provide some unique advantages in more manageable two stage to orbit configurations."

That's what people are responding to.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 04/15/2015 07:11 pm
Agreed that USAF is probably not looking to SABRE for just orbital launch, but in the press release, Barry Hellman (USAF Program Manager) weighs in on the SSTO/TSTO topic by saying:

Quote
"Although application of the SABRE for single stage to orbit space access remains technically very risky as a first application, the SABRE may provide some unique advantages in more manageable two stage to orbit configurations."

That's what people are responding to.

Since we think that SABRE might not scale down all that well, what are the options for vehicles with only one SABRE engine, full size?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 04/15/2015 07:18 pm
It's an interesting question that was raised a few pages back. See this post and the replies: http://forum.nasaspaceflight.com/index.php?topic=36826.msg1335441#msg1335441
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 04/15/2015 07:31 pm
http://www.reactionengines.co.uk/press_release.html (http://www.reactionengines.co.uk/press_release.html)

New press release from Reaction Engines

Looks like the USAF agrees with ESA with regards the feasability of the SABRE concept

From the press release:

Quote
"Although application of the SABRE for single stage to orbit space access remains technically very risky as a first application, the SABRE may provide some unique advantages in more manageable two stage to orbit configurations."

Given the huge projected development cost of the SSTO version, I kind of agree with that.

Many of us has argued that from the start. But some staunch Skylon supporters (like John Smith 19) think it has to be SSTO or nothing. The logic of that escapes me, but then again they also seem to find smaller versions of Skylon (to test technology) to be a waste of time. Skylon needs to be a massive SSTO, apparently.   

Boeing didn't start out by building 747's. The 747 wasn't even their first jet aircraft.

The 747 analogy is a false, Boeing after all DID build and fly an "SSTO" right from the start without even doing subscale testing or anything :)
(http://en.wikipedia.org/wiki/Boeing, Boeing Model 1 :) )
The reason for REL insisting that Skylon be  an SSTO is not for technical testing purposes. They expect to accomplish that with subscale and other testing, but as explained over and over again to you and others the economics don't work as well for a TSTO as for an SSTO. Will the Skylon BE built as an SSTO? If REL has anything to say about it then they will very much argue the economics aspect from their point-of-view, but in reality those funding the development will probably be in the form of a consortium and therefore REL will be only one voice.

And another factor is how "small" CAN you make a SABRE powered vehicle and get proper testing results? You CAN after all make a "SABRE" cycle LIKE engine with any cry-fluid but the deep cooling of the air pretty much takes LH2 to accomplish so using something else how accurate is the result? A small LH2 powered demonstrator would be all sort of helpful I'm sure but how much will it help "convince" investors and contributors? Frankly I'd be surprised if anyone who "doubts" a full up Skylon NOW would be convinced with anything short of... Well, a full up Skylon flying to orbit and back :)

The technical risk for development is high, but given the margin available not as high as say for a pure rocket powered SSTO. And the rewards are higher yet if it succeeds.

Given the huge projected development cost of the SSTO version, I kind of agree with that.

They could, for example, leave the atmosphere at lower speed, in order to reduce aerodynamic pressure, and reenter at Mach 15 or so instead of orbital speed. The vehicle would then land downrange similar to the Hopper concept and could be towed back to Kourou.

An upper stage with Vinci could do the rest. It would probably fit into the vehicle (with a longer bay obviously).

Any other ideas?

Lots and lots as hypersonic carriers launching expendable and reusable upper stages has been discussed and studied for decades. REL says their work shows it's not as cost effective as going straight to SSTO, and frankly the many air-breathing/rocket TSTO proposals tend to show that the air-breathing carrier aircraft is the most expensive part of the system no matter WHAT the propulsion cycle, and as we're all aware with Skylon the air-breathing portion of the flight while the most significant overall with ISP and delta-v is actually very little of the whole flight trajectory.

Really, I think if REL was to announce tomorrow that the SABRE included a SCramjet cycle the AF (and a lot of other folks) would suddenly find the whole idea of SSTO a LOT less "risky" or what reason I can't imagine :)

To seriously address a TSTO vehicle with SABRE engines what it amounts to is pretty much exactly the same flight profile as proposed for the Skylon; Take off and acceleration under air-breathing SABRE power to Mach-5+ then switching to pure rocket SABRE to Mach-10 to Mach-15+ outside the effective atmosphere with the release of the upper stage from that point. (For you imagination, take the twin-vertical version of the Skylon and recess a second stage just behind the point where the fuselage is maximum diameter and that's what it would look like)

And then ask yourself if, using the structural mass and propellant mass from the "second stage" you couldn't get the "carrier" aircraft up to around Mach-20 and orbit with about the same payload margin that's projected for the SSTO version of Skylon... And all your getting for the cost of two vehicle development programs, (please don't anyone think for a moment you can use an "off-the-shelf" rocket for a second stage) is a small increase in payload to orbit.

As an operational note, the Hopper as far as I understand it is CARRIED back to the launch site not towed and any operational SABRE powered vehicle will be fully capable of self-ferry by its nature. Unlike a rocket powered vehicle :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Oli on 04/15/2015 08:05 pm
To seriously address a TSTO vehicle with SABRE engines what it amounts to is pretty much exactly the same flight profile as proposed for the Skylon; Take off and acceleration under air-breathing SABRE power to Mach-5+ then switching to pure rocket SABRE to Mach-10 to Mach-15+ outside the effective atmosphere with the release of the upper stage from that point. (For you imagination, take the twin-vertical version of the Skylon and recess a second stage just behind the point where the fuselage is maximum diameter and that's what it would look like)

And then ask yourself if, using the structural mass and propellant mass from the "second stage" you couldn't get the "carrier" aircraft up to around Mach-20 and orbit with about the same payload margin that's projected for the SSTO version of Skylon... And all your getting for the cost of two vehicle development programs, (please don't anyone think for a moment you can use an "off-the-shelf" rocket for a second stage) is a small increase in payload to orbit.

As an operational note, the Hopper as far as I understand it is CARRIED back to the launch site not towed and any operational SABRE powered vehicle will be fully capable of self-ferry by its nature. Unlike a rocket powered vehicle :)

- That's pretty much what I was proposing, except maybe earlier switching to rocket mode if atmospheric heating is an issue at high Mach but I don't know that (max q is at around Mach 3+, so that's not a reason).

- If the upper stage has a propellant mass fraction of 0.9 staging at Mach 15 gives me ~2.5x the payload (Skylon C1). In any case, this isn't only about more payload or making the vehicle smaller, it's about having more margins to work with. I know some people here say it's basically all "standard tech", but as layman who is only capable of "comparing stuff" I'm very sceptical about that.

- Well Skylon is a good glider so I would go easy on those engines and tow the vehicle. You know, when people say 200 reuses it makes me suspicious.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 04/15/2015 08:32 pm

Agreed that USAF is probably not looking to SABRE for just orbital launch, but in the press release, Barry Hellman (USAF Program Manager) weighs in on the SSTO/TSTO topic by saying:

Quote
"Although application of the SABRE for single stage to orbit space access remains technically very risky as a first application, the SABRE may provide some unique advantages in more manageable two stage to orbit configurations."

That's what people are responding to.

Since we think that SABRE might not scale down all that well, what are the options for vehicles with only one SABRE engine, full size?

A question best asked maybe of Lockheed Martin as they are the ones trying to sell the idea of a hypersonic aircraft to the USAF.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/15/2015 08:36 pm
Many of us has argued that from the start.
And you didn't email REL to share your profound wisdom with them?
Quote
But some staunch Skylon supporters (like John Smith 19) think it has to be SSTO or nothing.
I "support" anything that lowers the $/lb price of a reasonable size payload to LEO.

REL are the only company that look to have a complete plan to get there.
Quote
The logic of that escapes me, but then again they also seem to find smaller versions of Skylon (to test technology) to be a waste of time. Skylon needs to be a massive SSTO, apparently.   
That's REL's position. Personally I'd like to see a smaller vehicle fly the whole mission but that means you've just spent a metric shedload of cash to do the same thing with virtually no payload and I know enough about the properties of LH2 to know what a major PITA making those pumps (at the same chamber pressure, which they'd have to be to keep the size down) would be see why they'd want to avoid that. 

When you make statements perhaps you could try for a little more accuracy?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 04/15/2015 08:44 pm
As far as I can tell it's only possible to judge the viability of Skylon as SSTO once you have confidence in the following:

1] The viability of the SABRE cycle - even in theory.
2] The real-life performance of a working SABRE.
3] The design and mass of the Skylon airframe around the SABRE .

It sounds like the USAF did not look at the airframe, so we could be hearing just the same informed guess you'd expect from anyone in the industry, i.e. SSTO margins are small, so it's risky.

Between the ESA and AFRL evaluations we can say 1] has been achieved. Next we need similar confidence in 2 and 3.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: topsphere on 04/15/2015 09:25 pm
Richard Varvill's talk has now been uploaded at:

https://player.vimeo.com/video/124910371

Everyone should watch it, it's quite a good viewing.

Although I have to say that watching it online where I can pause and have a think about what is being said makes for a much more informative lecture than live at the venue, where I felt like I couldn't possibly remember everything he was saying!!
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 04/15/2015 09:55 pm
- If the upper stage has a propellant mass fraction of 0.9 staging at Mach 15 gives me ~2.5x the payload (Skylon C1).

No structural penalty on the first stage for shoehorning a big second stage into the existing design?

Also keep in mind that Skylon's payload is already large enough to capture the bulk of the market, and you can't scale the vehicle down because the combination of payload diameter requirements and aerodynamic considerations pretty much dictate its current size (believe it or not it has nothing to do with using LH2).  Is dual-manifest worth a potential increase in the development costs (your number assumes Skylon stats as advertised for the first stage, so it isn't easier to develop) as well as manufacturing, shipping, mating, and ground support for a brand-new fairly large upper stage on every flight, not to mention the downrange landing and the lack of on-orbit retrieval and downmass capability?

This is assuming REL are in the ballpark regarding airframe mass and engine performance, of course.  A substantial mass increase could change the picture, as could a significant rocket-mode underperformance (though as I've said I don't expect the latter).  As Skylon C shows, there's a huge margin for error in SABRE 4's airbreathing performance before the vehicle concept becomes nonviable, but technically that could still happen too...

Richard Varvill's talk has now been uploaded at:

https://player.vimeo.com/video/124910371

Thanks!
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Oli on 04/15/2015 10:10 pm
No structural penalty on the first stage for shoehorning a big second stage into the existing design?

Also keep in mind that Skylon's payload is already large enough to capture the bulk of the market, and you can't scale the vehicle down because the combination of payload diameter requirements and aerodynamic considerations pretty much dictate its current size (believe it or not it has nothing to do with using LH2).

- Well the "first stage" doesn't reenter from orbit anymore and has less tank volume, could go both ways IMO.

- Yeah I know the shape is a PITA. You'd also have to rearrange the "internals" somehow to fit a stage in there. Maybe it would make sense to put the upper stage outside the vehicle. Adds a lot of drag of course. Other hypersonic designs have done that too though.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 04/15/2015 10:16 pm
Well the "first stage" doesn't reenter from orbit anymore and has less tank volume, could go both ways IMO.

Maybe, but REL says the Mach 5+ atmospheric flight is driving the TPS design just as much as the orbital reentry.  And as I said the tank volume isn't driving the shape - well, it is, in the sense that they had to make the fuselage shorter at the cost of increased drag to avoid wasting structural mass on empty space...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Oli on 04/15/2015 10:27 pm
Maybe, but REL says the Mach 5+ atmospheric flight is driving the TPS design just as much as the orbital reentry.  And as I said the tank volume isn't driving the shape - well, it is, in the sense that they had to make the fuselage shorter at the cost of increased drag to avoid wasting structural mass on empty space...

Define "driving just as much", doesn't mean they have the same requirements. At least the active cooling won't be required anymore. And why not go only to Mach 3 or so in the atmosphere? Well, that will lower the payload but might make other things easier. Regarding the tank, I thought the tank doesn't support the structure, so they could just make it smaller if there's less propellant without changing the shape.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: aceshigh on 04/15/2015 10:55 pm
Richard Varvill's talk has now been uploaded at:

https://player.vimeo.com/video/124910371

Everyone should watch it, it's quite a good viewing.

Although I have to say that watching it online where I can pause and have a think about what is being said makes for a much more informative lecture than live at the venue, where I felt like I couldn't possibly remember everything he was saying!!

you know, the subject was most interesting and I enjoyed the talk content, but either Varvill's is not a good speaker or it was a bad time for him. I found it somewhat of a snoozefest and Varvill's sounded like he wanted to be somewhere else, or that he was pessimistic about the future.

I hope Varvill's is not in charge of selling Skylon...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 04/15/2015 11:14 pm
Define "driving just as much", doesn't mean they have the same requirements. At least the active cooling won't be required anymore. And why not go only to Mach 3 or so in the atmosphere? Well, that will lower the payload but might make other things easier.

My point is that there are a lot of factors involved that make it less than immediately obvious that TSTO is a better solution.  REL seems to think it's not, and they're the ones who have been doing real engineering with numbers.  There is no indication that a comparable amount of analysis underlies the AFRL statement.

Quote
Regarding the tank, I thought the tank doesn't support the structure, so they could just make it smaller if there's less propellant without changing the shape.

Yes, but then the structure and aeroshell are bigger than they need to be, which adds mass, and that trades against supersonic drag.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 04/15/2015 11:36 pm
Richard Varvill's talk has now been uploaded at:

https://player.vimeo.com/video/124910371

Everyone should watch it, it's quite a good viewing.

Although I have to say that watching it online where I can pause and have a think about what is being said makes for a much more informative lecture than live at the venue, where I felt like I couldn't possibly remember everything he was saying!!

you know, the subject was most interesting and I enjoyed the talk content, but either Varvill's is not a good speaker or it was a bad time for him. I found it somewhat of a snoozefest and Varvill's sounded like he wanted to be somewhere else, or that he was pessimistic about the future.

I hope Varvill's is not in charge of selling Skylon...

Speaking personally, if I'd been giving roughly same presentation for 10+ (20?) years, I too would have a hard time sounding enthusiastic! My hats off to them for keeping true to their vision over these long years. (I'm one of those kids who read about HOTOL with excitement in the '80s).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: dror on 04/16/2015 11:37 am
You CAN after all make a "SABRE" cycle LIKE engine with any cry-fluid but the deep cooling of the air pretty much takes LH2 to accomplish so using something else how accurate is the result?

Randy

So I don't realy understand. Is the SABRE cycle even possible with other cryogenic fuel or not?
Strictly theoretically, is it possible with deep cooled methan for instance,  or is it not cold enogh to "liquify" the air?

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: dasmoth on 04/16/2015 01:55 pm
At LonCon last year, Alan Bond said LH2 was the only viable option.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 04/16/2015 03:05 pm
You CAN after all make a "SABRE" cycle LIKE engine with any cry-fluid but the deep cooling of the air pretty much takes LH2 to accomplish so using something else how accurate is the result?

So I don't realy understand. Is the SABRE cycle even possible with other cryogenic fuel or not?
Strictly theoretically, is it possible with deep cooled methane for instance,  or is it not cold enogh to "liquify" the air?

"SABRE-like" would mean a cycle that approximates but does not duplicate the SABRE. Off the top of my head I used an example of Mass Injection, Pre-Compressor Cooling or MIPCC which uses injected water and LOX to densify and concentrate the incoming air. You COULD use liquid methane and other cryo-fluids as injection fluids, (tests have been done with liquid nitrogen for verification of the MIPCC effects on turbo-machinery) but none of the really come to the point of DEEP cooling the air.

It actually DOES take liquid hydrogen to accomplish by the SABRE cycle. LH2 is what is know as a "hard" cryogen due to its VERY cold liquefaction temperature, (-252c/-423f) compared to other cryogenic fluids. For example methane FREEZES at -182c/-294f and its boiling point is higher as well at -161c/-258f. Your components of air (nitrogen/oxygen) liquefy at -196c/-320f and -182c/297f respectively. That's if we wanted to use something like a LACE (Liquid Air Cycle Engine) system though were we were actually making liquid oxygen for the engine, what we're talking about it simply "deep" cooling which require a lot less cooling. But we're also NOT talking about "normal" temperature air either. At Mach-5 the incoming air is going to be very hot BEFORE it's compressed and fed into the engine and only LH2 has the thermal capacity to reduce that temperature AND still drop the air temperature to a point where it can be dense enough to feed into the engine.

The main mechanical "sticking point" has always been the heat exchanger for deep cooling air for a turbo-machine application. Flow, Frost, and most other problem have been solved numerous times for various designs but mass was always an issue and REL has pretty much solved their problems with those factors with the current SABRE cycle. The OTHER more problematical issue has been that despite having worked out and proven in laboratory testing that deep cooling allowed all the advantages of LACE without most of the problems there was an industry and academic wide misunderstanding (blind spot really) that in order to run a ROCKET engine on "air" that propellant had to be made from a "gas" (which could be run in a turbo-compressor but not run through turbo-pump, the former being a jet engine the latter being "required" to inject propellant into an rocket engine) into a liquid.

I say this was a "blind spot" for the simple reason that even when it was PROVEN in lab testing that you in fact COULD deep cool air to a point where it could be run through a turbo-pump and fed into a rocket engine AS A GAS not only was this ignored by the majority of people working on the subject, the program that DID this mis-named the process by calling "turbo-LACE" which by definition would suggest that at some point the "air" becomes a "liquid" as its CALLED a version of the Liquid Air Cycle Engine...
(And in a classic case of the rocket engine people not talking to the jet engine people it was categorically stated in the literature of the time that you REQUIRED propellant to be liquid in order to run them through turbo-pumps to get high pressure in a rocket engine at the VERY same time the people producing what was to become the RL-10 LH2/LOX rocket engine were producing papers and studies showing how much MORE efficient it was to inject the propellants THROUGH A TURBO-PUMP as a GAS instead of a LIQUID! ::::doublefacepalm:::: Couple this with the obsession with the "perfect" air-breathing engine which {in theory} is the SCramjet and its pretty clear why its take REL going back and asking the "basic" questions again and NOT accepting the "common knowledge" to get to the point we are now)

You CAN do "SABRE-like" with other cryogen-propellants but the actual cycle(s) are very different and in most cases won't be as efficient at SABRE is supposed to be.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SteveKelsey on 04/16/2015 05:38 pm
A lateral question at this point considering the detail of the discussion but with this

 "Furthermore, the heat exchanger technology also warrants further investigation for applications across the aerospace domain"

 indicating interest by the USAF,  will SABRE technology get snared in ITAR problems. I am delighted that SABRE has received the endorsement, but would hate to see Reaction Engine's IP inadvertently sequestered.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/16/2015 06:46 pm
indicating interest by the USAF,  will SABRE technology get snared in ITAR problems. I am delighted that SABRE has received the endorsement, but would hate to see Reaction Engine's IP inadvertently sequestered.
An excellent point.

The Official UK position on ITAR was described in the BSA's report on UK spaceports.

It makes depressing reading and you'd have to be very careful to ensure that any SABRE/Skylon IP is not "contaminated" by USAF work, effectively making the USG a business partner and giving it power of veto over your decisions.  :(

That might not be a position the British government is too bothered by but it should scare the hell out of any  British company that wants to be predominately  a supplier to the world in aerospace.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 04/16/2015 07:17 pm
indicating interest by the USAF,  will SABRE technology get snared in ITAR problems. I am delighted that SABRE has received the endorsement, but would hate to see Reaction Engine's IP inadvertently sequestered.
An excellent point.

The Official UK position on ITAR was described in the BSA's report on UK spaceports.

It makes depressing reading and you'd have to be very careful to ensure that any SABRE/Skylon IP is not "contaminated" by USAF work, effectively making the USG a business partner and giving it power of veto over your decisions.  :(

That might not be a position the British government is too bothered by but it should scare the hell out of any  British company that wants to be predominately  a supplier to the world in aerospace.  :(

The key phrase is "across the aerospace domain" rather than something directly applicable to "rocket/missile" technology. ITAR legally is about home made missiles not home made bombers and drones which is why model "rockets" get a hard time while GPS guided "autonomous and remote control" aircraft don't :)

As I asked earlier, one possible interesting application is a 'reverse' HE where heat is transferred FROM another source into an airstream, uses such as in turbo-heat-exchangers comes to mind as well.

It's not "just" for cooling anymore :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/16/2015 07:27 pm
Just to be clear what the CRADA says

The USAF accept that the SABRE 3 does work and at no point violates the laws of Thermodynamics provided the components can be be built to meet the thermal and structural requirements in different parts of the system.

NSF posters will already know that the core of the SABRE engines is the precooler and this has already been tested, due to it having the most demanding set of requirements in terms of airflow, temperature difference, frost control etc.

Some of the USAF's views are a bit odd. The SABRE cycle is specifically designed for flight to orbit. I think it would be superior for acceleration to M5 (during a launch) but if they wanted an engine for M5 they should have been aware of REL's LAPCAT work, which is a completely different cycle, optimized for M5 cruise.

I think it's very clear from their choice of the SABRE cycle and willingness to look at cryogens that this work is specifically aimed at launching payloads ASAP, the so called "responsive space" notion.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 04/16/2015 07:59 pm
May I at this point out that for the second time that 20 billion dollars (my random, but somewhat educated guess at current cost now) is not a lot of money in terms of US govt spending...

I am slightly concerned about IP having been already handed over in this CRADA process however...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 04/16/2015 08:35 pm

May I at this point out that for the second time that 20 billion dollars (my random, but somewhat educated guess at current cost now) is not a lot of money in terms of US govt spending...

I am slightly concerned about IP having been already handed over in this CRADA process however...

But it's not chicken feed either especially these days when even the USAF is feeling the pinch hence why they keep trying to retire various aircraft so they can fund things like the F-35.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: docmordrid on 04/17/2015 01:17 am
It probably should be pointed out that the USAF is formulating proposals for a next generation bomber and a 6th generation fighter, with hypersonic.on the wish list for the latter.



Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 04/17/2015 06:21 am
It probably should be pointed out that the USAF is formulating proposals for a next generation bomber and a 6th generation fighter, with hypersonic.on the wish list for the latter.

The bomber is well, well beyond formulating proposals being as they've effectively admitted to it being at the prototype stage so isn't relevant here.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: momerathe on 04/17/2015 02:59 pm
Honestly, the press release makes my previous gut feel that much stronger - it's Scimitar the USAF really want.

Could REL develop the two engines in parallel? I'm going to say no. Regardless of the similarities, I would expect the detailed engineering on either one would consume their entire energies.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 04/17/2015 05:17 pm
Honestly, the press release makes my previous gut feel that much stronger - it's Scimitar the USAF really want.

Could REL develop the two engines in parallel? I'm going to say no. Regardless of the similarities, I would expect the detailed engineering on either one would consume their entire energies.

Actually I've always thought that too. The CRADA might have specified SABRE, but it seems extremely unlikely that the investigations didn't involve all types of uses they were interested in.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 04/17/2015 06:41 pm

Honestly, the press release makes my previous gut feel that much stronger - it's Scimitar the USAF really want.

Could REL develop the two engines in parallel? I'm going to say no. Regardless of the similarities, I would expect the detailed engineering on either one would consume their entire energies.

Totally agree that's what the USAF will be interested in not SABRE itself. There has been indications that the USAF would like to have some kind of hypersonic technological demonstrator in the air before the turn of the decade. How achievable that kind of target is for REL on the propulsion side whilst still trying to develop SABRE is anyone's guess.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/17/2015 06:45 pm
Honestly, the press release makes my previous gut feel that much stronger - it's Scimitar the USAF really want.

Could REL develop the two engines in parallel? I'm going to say no. Regardless of the similarities, I would expect the detailed engineering on either one would consume their entire energies.
It's clear what the CRADA studied. It's equally clear that SABRE's focus is single stage to orbit launch and if the USAF chose to ignore that point that's their decision.

I will note that SABRE and Skylon are separate  designs. If the USAF were so minded they could look at a more conservative airframe that traded payload for more traditional aerospace materials.

How small I don't know. Part of it would depend on wheather they wanted orbit from a CONUS site, rather than an equatorial site. It would be an option.

Actually I've always thought that too. The CRADA might have specified SABRE, but it seems extremely unlikely that the investigations didn't involve all types of uses they were interested in.

It's not the use. LAPCAT's internals are completely different, with the turbine outside the core. IIRC it trades higher weight for better LH2 economy and of course eliminates all the air sealing system as it runs in atmosphere all the time.

May I at this point out that for the second time that 20 billion dollars (my random, but somewhat educated guess at current cost now) is not a lot of money in terms of US govt spending...

I am slightly concerned about IP having been already handed over in this CRADA process however...
The cargo transport contract to the ISS is about $18Bn

$20Bn is about a 66% rise on the last REL estimate I'm aware of ($12Bn.) That last rise was caused by including the Skylon Upper Stage to take payloads to GTO as part of the baseline development.

That's a lot of inflation compared to REL's estimate.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: dror on 04/17/2015 07:00 pm

$20Bn is about a 66% rise on the last REL estimate I'm aware of ($12Bn.) That last rise was caused by including the Skylon Upper Stage to take payloads to GTO as part of the baseline development.


Is that Skylon Upper Stage planned to be reusable and return to the Skylon befor reentry or expendable?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 04/17/2015 07:07 pm
Honestly, the press release makes my previous gut feel that much stronger - it's Scimitar the USAF really want.

Could REL develop the two engines in parallel? I'm going to say no. Regardless of the similarities, I would expect the detailed engineering on either one would consume their entire energies.
It's clear what the CRADA studied. It's equally clear that SABRE's focus is single stage to orbit launch and if the USAF chose to ignore that point that's their decision.

I will note that SABRE and Skylon are separate  designs. If the USAF were so minded they could look at a more conservative airframe that traded payload for more traditional aerospace materials.

How small I don't know. Part of it would depend on wheather they wanted orbit from a CONUS site, rather than an equatorial site. It would be an option.

Actually I've always thought that too. The CRADA might have specified SABRE, but it seems extremely unlikely that the investigations didn't involve all types of uses they were interested in.

It's not the use. LAPCAT's internals are completely different, with the turbine outside the core. IIRC it trades higher weight for better LH2 economy and of course eliminates all the air sealing system as it runs in atmosphere all the time.

Ok. But I am sure the USAF can use their imagination :)

May I at this point out that for the second time that 20 billion dollars (my random, but somewhat educated guess at current cost now) is not a lot of money in terms of US govt spending...

I am slightly concerned about IP having been already handed over in this CRADA process however...
The cargo transport contract to the ISS is about $18Bn

$20Bn is about a 66% rise on the last REL estimate I'm aware of ($12Bn.) That last rise was caused by including the Skylon Upper Stage to take payloads to GTO as part of the baseline development.

That's a lot of inflation compared to REL's estimate.  :(

You're right. I believe you are referring to last, fairly recent, estimates which included a reduction in price owing to potential new manufacturing approaches (was it manufacturing?). So I completely take that back. I was going by the old, old, oft quoted GBP price,  rounding up quite a lot for years passed and then adding a hefty conversion to dollars. Very back of envelope and prob very inaccurate.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/17/2015 07:27 pm
Is that Skylon Upper Stage planned to be reusable and return to the Skylon befor reentry or expendable?
It's designed for 10 reuses running on LH2/LO2 through a pair of the SOMA engines. It uses the idea of the duration for an orbit to near GEO being a sub multiple of the period of the Skylon's  orbit (so called "resonant" orbits) so it "falls" back to the Skylon orbit and the Skylon is in place to pick it up than bring it back.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 04/17/2015 08:06 pm

Honestly, the press release makes my previous gut feel that much stronger - it's Scimitar the USAF really want.

Could REL develop the two engines in parallel? I'm going to say no. Regardless of the similarities, I would expect the detailed engineering on either one would consume their entire energies.
It's clear what the CRADA studied. It's equally clear that SABRE's focus is single stage to orbit launch and if the USAF chose to ignore that point that's their decision.

I will note that SABRE and Skylon are separate  designs. If the USAF were so minded they could look at a more conservative airframe that traded payload for more traditional aerospace materials.

How small I don't know. Part of it would depend on wheather they wanted orbit from a CONUS site, rather than an equatorial site. It would be an option.

Actually I've always thought that too. The CRADA might have specified SABRE, but it seems extremely unlikely that the investigations didn't involve all types of uses they were interested in.

It's not the use. LAPCAT's internals are completely different, with the turbine outside the core. IIRC it trades higher weight for better LH2 economy and of course eliminates all the air sealing system as it runs in atmosphere all the time.

May I at this point out that for the second time that 20 billion dollars (my random, but somewhat educated guess at current cost now) is not a lot of money in terms of US govt spending...

I am slightly concerned about IP having been already handed over in this CRADA process however...
The cargo transport contract to the ISS is about $18Bn

$20Bn is about a 66% rise on the last REL estimate I'm aware of ($12Bn.) That last rise was caused by including the Skylon Upper Stage to take payloads to GTO as part of the baseline development.

That's a lot of inflation compared to REL's estimate.  :(

If you think everything that was studied was detailed in that press release then I would say that you would be mistaken.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 04/17/2015 08:13 pm
It IS important to note that the AF looked at the SABRE and its cycle specifically. As noted the HE itself has other uses that make the technology important to study but the cycle itself DOES actually have some uses beyond orbital launch, though NOT in a Skylon type vehicle :)

For example it could be used in a Hypersoar (http://en.wikipedia.org/wiki/HyperSoar) which does skip-glides at speeds of less than Mach-12. (Studies show a "sweet-spot" around Mach-6 actually) Or a deep cooled engine using another cycle is possible (http://www.secretprojects.co.uk/forum/index.php?topic=6422.0, http://www.secretprojects.co.uk/forum/index.php?topic=6422.0, etc) are possible as well.

The main point of contention is operationally the AF would rather avoid LH2 propellant if at all possible, however the CRADA makes it pretty clear that the entire operation of the SABRE cycle DEPENDS on using LH2 and deep cooling, (which it does) and so any consideration of using the technology has to take that into account.

That little item in and of itself is the main point of the whole exercise IMO. This points out very distinctly that while you can have other cycles that can possibly do what the SABRE does, the SABRE itself REQUIRES LH2 so any plans to utilize the cycle require the use of LH2. The AF has in the past has used H2O2, hydrazine, IRFNA, and other toxic and dangerous propellants but they have ONLY considered (and used) LH2 when they had no other choice for the mission they wanted. (And gladly dropped it if ANY other option was available) The wording tells me that someone, somewhere was of the mind that they could use the SABRE cycle without the LH2, ("Liquid Methane is cold, we really don't need LH2") and this pretty much puts the last nail in that coffin as it were. You want to use the SABRE cycle you have to use LH2, you don't want to do that then this cycle isn't for you.

So IF the AF wants this for a launch vehicle expect to hear more, if they are looking for anything else it won't be using the SABRE or LH2 :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/18/2015 08:50 am
...and this pretty much puts the last nail in that coffin as it were. You want to use the SABRE cycle you have to use LH2, you don't want to do that then this cycle isn't for you.

So IF the AF wants this for a launch vehicle expect to hear more, if they are looking for anything else it won't be using the SABRE or LH2 :)
With the Delta IV and Centaur the USAF have demonstrated they will tolerate LH2 for certain specific tasks, primarily launch.

Outside that area I don't think they can get their can let go their preconceptions to use it for anything else, and there's simply no way anything like SABRE can work with anything like a normal liquid hydrocarbon.   :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: mhlas7 on 04/18/2015 06:15 pm
Is that Skylon Upper Stage planned to be reusable and return to the Skylon befor reentry or expendable?
It's designed for 10 reuses running on LH2/LO2 through a pair of the SOMA engines. It uses the idea of the duration for an orbit to near GEO being a sub multiple of the period of the Skylon's  orbit (so called "resonant" orbits) so it "falls" back to the Skylon orbit and the Skylon is in place to pick it up than bring it back.
Are there any ballpark numbers for what the payload mass to GEO/GTO might be? I realize that the vehicle and engines are still very theoretical but are we talking about ~6T comsats, ~2T delta class payloads or <1T small sats?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 04/18/2015 07:48 pm
Is that Skylon Upper Stage planned to be reusable and return to the Skylon befor reentry or expendable?
It's designed for 10 reuses running on LH2/LO2 through a pair of the SOMA engines. It uses the idea of the duration for an orbit to near GEO being a sub multiple of the period of the Skylon's  orbit (so called "resonant" orbits) so it "falls" back to the Skylon orbit and the Skylon is in place to pick it up than bring it back.
Are there any ballpark numbers for what the payload mass to GEO/GTO might be? I realize that the vehicle and engines are still very theoretical but are we talking about ~6T comsats, ~2T delta class payloads or <1T small sats?

http://forum.nasaspaceflight.com/index.php?topic=33648.msg1207876#msg1207876

About 6.4 tonnes if the SUS is reused, 8 tonnes if it's expended.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 04/18/2015 07:51 pm

With the Delta IV and Centaur the USAF have demonstrated they will tolerate LH2 for certain specific tasks, primarily launch.


It is not a "toleration"    Space launch USAF is not the same as the USAF that would want to use the SABRE for other reasons. 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/18/2015 08:52 pm
Are there any ballpark numbers for what the payload mass to GEO/GTO might be? I realize that the vehicle and engines are still very theoretical but are we talking about ~6T comsats, ~2T delta class payloads or <1T small sats?
In addition a SUS can put a satellite with an eletric thruster in a 5900 Km radius orbit above the Van Allan belt so it's not cooked as it reaches orbit. Assuming a 20Kw Hall thruster that would be the eqivalent of close to a 9 tonne sat  to GTO or over 5 1/2 tonnes at GEO.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/18/2015 09:02 pm
It is not a "toleration"    Space launch USAF is not the same as the USAF that would want to use the SABRE for other reasons.
True.

The "winged" side ofthe USAF seems much less happy about any cryogen that I'm surprised they'd look at SABRE, despite the fact it's looking like the only engine that's coming anywhere close to being built at full size  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 04/20/2015 06:50 am
On other sites I've seen people asking why it cost so much to develop SABRE compared to rocket engines in other vehicles, specifically the SpaceX ones. I don't actually know if it is all that expensive comparatively but to myself I answer "reusability".

So I was wondering about this kind of thing :-) :
http://aviationweek.com/space/rocket-lab-unveils-battery-powered-turbomachinery

Presumably it doesn't scale or something like that. Nevertheless,  if there was some new risk that offered a possible way to cut the cost of either developing or building SABRE, would it be worth going for?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/20/2015 11:31 am
On other sites I've seen people asking why it cost so much to develop SABRE compared to rocket engines in other vehicles, specifically the SpaceX ones. I don't actually know if it is all that expensive comparatively but to myself I answer "reusability".

So I was wondering about this kind of thing :-) :
http://aviationweek.com/space/rocket-lab-unveils-battery-powered-turbomachinery

Presumably it doesn't scale or something like that. Nevertheless,  if there was some new risk that offered a possible way to cut the cost of either developing or building SABRE, would it be worth going for?
It might seem like a reasonable comparison but it's not really a fair one.

In theory both engines are designed for reuse but there the similarity ends.

The gas generator cycle is the most common pumped engine cycle in any propellant combination. There is a lot of prior art on how to build them regarding materials compatibility, design choices and tools  etc.

In contrast there is limited experience of pumped LH2/LO2 engines anywhere with 4 designs in the US (and the only production design dating from the 1960's) with 2 in Europe and 1 (IIRC) in Russia.

SABRE is also roughly 3x bigger than Merline and due to be tested in one of the most populous countries of Europe, making H&S and availability of test stands very big issues.  :(

A fairer comparison would have been the SSME programme. A first of its kind engine using LH2.

I emphasize LH2 because it's much harder to deal with. Typically all LH2 pipework uses welded steel pipes one in side the other, with a vacuum between. "Vacuum Jacket Line" is not cheap and will need to fitted to the SABRE test stands. There are no good ways to simulate LH2's temperature or it's compressibility. AFAIK LH2 is the only common liquid that at "reasonable" pressures (100s, not 1000s of atmospheres) can be compresses by several percent of its normal volume, making pump design especially tricky.  :(

SABRE is a first of its kind design and the only one operating over the M0-M23-M0 speed range.

The SABRE development programme is roughly $300m, I'd guess that's peanuts relative to the inflation adjusted costs of the SSME.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Krevsin on 04/20/2015 12:18 pm
...and this pretty much puts the last nail in that coffin as it were. You want to use the SABRE cycle you have to use LH2, you don't want to do that then this cycle isn't for you.

So IF the AF wants this for a launch vehicle expect to hear more, if they are looking for anything else it won't be using the SABRE or LH2 :)
With the Delta IV and Centaur the USAF have demonstrated they will tolerate LH2 for certain specific tasks, primarily launch.

Outside that area I don't think they can get their can let go their preconceptions to use it for anything else, and there's simply no way anything like SABRE can work with anything like a normal liquid hydrocarbon.   :(
Could SABRE potentially work with methalox?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 04/20/2015 01:16 pm
Could SABRE potentially work with methalox?

Not cold enough. See: http://forum.nasaspaceflight.com/index.php?topic=36826.msg1360152#msg1360152

With the Delta IV and Centaur the USAF have demonstrated they will tolerate LH2 for certain specific tasks, primarily launch.

Outside that area I don't think they can get their can let go their preconceptions to use it for anything else, and there's simply no way anything like SABRE can work with anything like a normal liquid hydrocarbon.   :(
It is not a "toleration"    Space launch USAF is not the same as the USAF that would want to use the SABRE for other reasons.
True.

The "winged" side of the USAF seems much less happy about any cryogen that I'm surprised they'd look at SABRE, despite the fact it's looking like the only engine that's coming anywhere close to being built at full size  :(

Actually we've built a few "full-size" engines for various cycles in the past. What we haven't done is fly them :)

Mostly it's an operational thing in that the majority of infrastructure is based on hydrocarbon fuel. If LH2 use and infrastructure were as large there might be less opposition. But given the reduction rather than expansion of LOX operations as the overall infrastructure has grown for civil use I'm pretty sure LH2 by the AF will remain a VERY limited segment of operations :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 04/20/2015 08:17 pm
The SABRE development programme is roughly $300m, I'd guess that's peanuts relative to the inflation adjusted costs of the SSME.

That's $£360M to get to first working prototype.  Which is about 1/10 of the whole engine development programme, which suggests that their cost estimate includes everything it's supposed to to get the engine into actual production...

EDIT:  Metric vs. Imperial money confusion...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 05/09/2015 07:00 pm
Regarding the placement of any future UK spaceport - now that the results of the UK election make the breakup of the UK much more likely (and possibly within 5-10 years), I'd wager that the powers that be will be reluctant to put any money into placing the spaceport in Scotland.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 05/10/2015 03:24 am
Regarding the placement of any future UK spaceport - now that the results of the UK election make the breakup of the UK much more likely (and possibly within 5-10 years), I'd wager that the powers that be will be reluctant to put any money into placing the spaceport in Scotland.

Possibly, but the British Government is likely to go the other way - use the spaceport as a bribe. Since the Scottish Nationalists are an extreme left wing group (for instance they want Britain's nuclear weapons removing from Scotland) who already control most social spending in Scotland they cannot be bribed with military contracts.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 05/10/2015 05:28 am

Quote from  AM Swallow on: Today at 03:24 AM - sorry I didn't quote this properly when I first wrote it
Quote
Possibly, but the British Government is likely to go the other way - use the spaceport as a bribe. Since the Scottish Nationalists are an extreme left wing group (for instance they want Britain's nuclear weapons removing from Scotland) who already control most social spending in Scotland they cannot be bribed with military contracts.

I don't think the SNP is bribable. Anything you give them, they will present to Scotland as their spoils of war, enhancing their position and increasing the likelihood of them leaving.   It is important for the government to ensure that credit for whatever happens will be attributed to the union.  Something like Skylon might be exceedingly good at that in the way that the aircraft carriers and the type 26 destroyers are.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 05/10/2015 05:53 am
Quote
Possibly, but the British Government is likely to go the other way - use the spaceport as a bribe. Since the Scottish Nationalists are an extreme left wing group (for instance they want Britain's nuclear weapons removing from Scotland) who already control most social spending in Scotland they cannot be bribed with military contracts.

I don't think the SNP is bribable. Anything you give them, they will present to Scotland as their spoils of war, enhancing their position and increasing the likelihood of them leaving.   It is important for the government to ensure that credit for whatever happens will be attributed to the union.  Something like Skylon might be exceedingly good at that in the way that the aircraft carriers and the type 26 destroyers are.

The SNP needs to bring a spoil of war back to Scotland. If they come back with nothing then they will be seen as failures. The Conservative majority is sufficient that the SNP could be ignored/bypassed for the next 3-5 years.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/10/2015 08:18 am
Regarding the placement of any future UK spaceport - now that the results of the UK election make the breakup of the UK much more likely (and possibly within 5-10 years), I'd wager that the powers that be will be reluctant to put any money into placing the spaceport in Scotland.
Incorrect.

You might like to look at the actual results

http://en.wikipedia.org/wiki/Scottish_independence_referendum,_2014

84% of the eligible electorate voted and the No (to independence) was about 10 percentage points greater than the yes result. For comparison IIRC a better than 50% turnout for the US Presidential election is viewed as good.

This was despite the Scottish Nationalist Party setting the schedule for the vote, the actual question itself and allow 16-18 year olds (statistically likely to vote for the newer idea) to vote.

The leader of the SNP at the time resigned as he had failed, despite every advantage to their campaign. When push came to shove Scots people voted with their heads, not their hearts.

This issue is dead for 1 to 2 generations in Scotland at least.

So IMHO putting a spaceport in Scotland is a pretty safe bet.

BTW on the nuclear issue it's estimated supporting those subs takes about 7000 well paying Scots jobs, and while SNP policy is NIMBY they are pragmatic enough to know that's quite a big black hole to fill.

SABRE/Skylon is designed from the ground up as a civilian space vehicle. Any effort to "weaponize" it would be so complex you'd just as well build your own ICBM.

I think the Scottish government would be happy to welcome REL to the country.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 05/10/2015 08:27 pm
JS19
**This issue is dead for 1 to 2 generations in Scotland at least**

I respect your opinion on matters space-related, but your analysis here is out of step with most political analysts on this point. England has moved to the right. Despite their single seat, UKIP had a lot of support in the election, as judged by their percentage share of the vote. There will be a referendum on the EU in 2 years. If England votes to leave, the UK will break up because the Scots want to stay in the EU.

Even aside from the referendum on the EU, Scottish and English sentiments have diverged in recent years, particularly since the Thatcher years. Cameron's comments subsequent to the Scottish referendum last year have left many Scottish who voted to stay in the union feeling that they were shafted. For unionists, the best likely outcome is now some sort of federal union, but I would not bet against it going further and a fully independent Scotland emerging in the near future.

It is that uncertainty that will make those in power (England) very reluctant to place such a strategically important infrastructure project as the spaceport in an area that they may not have control of in 10 years.

**I think the Scottish government would be happy to welcome REL to the country.**

I certainly agree with you here, but it won't be a decision left to the parliament in Scotland. This decision will be made in London.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/11/2015 12:07 pm
JS19
**This issue is dead for 1 to 2 generations in Scotland at least**

I respect your opinion on matters space-related,
That's very flattering. I'll try to continue to live up to your expectations.   :)
Quote
but your analysis here is out of step with most political analysts on this point. England has moved to the right. Despite their single seat, UKIP had a lot of support in the election, as judged by their percentage share of the vote. There will be a referendum on the EU in 2 years. If England votes to leave, the UK will break up because the Scots want to stay in the EU.
It's my view people who want to break some stuff up tend to want to break all stuff up. IOW If you liked the idea of the UK leaving Europe you like the idea of Scotland leaving the UK.

Except when the Scots were given the opportunity more than 84% turned out and it was roughly 11 to 8 against leaving.

http://en.wikipedia.org/wiki/Scottish_independence_referendum,_2014

Looking at UKIP
http://www.bbc.co.uk/news/election/2015/results

People were predicting a)A hung House of Commons and b) UKIP to win 2 seats, including their Leader becoming an MP.

But when push came to shove 1 candidate (not the leader) got elected.  So they delivered 50% of their expected performance.  The Liberal Democrats were destroyed but they still managed to retain 8 seats. Even the political wing of a disbanded terrorist group has more seats in the House of Commons than UKIP.

This referendum (assuming it happens) is about Prime Minister Cameron retaining the support of a group of his (mostly) non ministerial MP's who remain obsessed with the idea of leaving the EU.

UKIP is to UK politics what Fox News is to CNN. You may be entertained by it but actually there's not that much there and they both have definite agendas, which you should be very conscious of.  :(

Quote
Even aside from the referendum on the EU, Scottish and English sentiments have diverged in recent years, particularly since the Thatcher years. Cameron's comments subsequent to the Scottish referendum last year have left many Scottish who voted to stay in the union feeling that they were shafted. For unionists, the best likely outcome is now some sort of federal union, but I would not bet against it going further and a fully independent Scotland emerging in the near future.
Either preliminary work will go ahead regardless in pursuit of this policy directive or all work will be delayed pending the referendum outcome. As it is a stated goal of the BSA to increase UK experience and skill in space engineering the simple option is to go ahead

If the result is for leaving the EU and if Scotland requests a 2nd independence referendum (BTW the Houses of Parliament are the body that granted the right to hold a referendum in the first place) then that will require review. That's 2 big "if's" in a row after the big one of wheather there will be a referendum at all.

It looks like Cameron said he will, but words can be ambiguous.  :(
Quote
It is that uncertainty that will make those in power (England) very reluctant to place such a strategically important infrastructure project as the spaceport in an area that they may not have control of in 10 years.
Unless they are confident enough that the bulk of the British people will vote to stay that they are not worried.  :)
Quote
**I think the Scottish government would be happy to welcome REL to the country.**

I certainly agree with you here, but it won't be a decision left to the parliament in Scotland. This decision will be made in London.
No. It will be made in Culham.

REL is a private company. The UK Govt is a minority investor and AFAIK have no management input.

They could just as easily go to Toulouse instead.

While it could be said this is loosely relevant to SABRE/Skylons future I think it's going quite far OT.

From REL's perspective their next big events (I think) will be getting the test stand for SABRE ready and of course getting the full size flight configuration (although not I suspect flight weight) engine ready for it.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 05/11/2015 02:13 pm
Regarding the likelihood of Scotland staying in the UK, we are in disagreement. As you say it's off-topic for this thread so we'd probably best not thrash it out here.

JS19
**No. It will be made in Culham.
REL is a private company. The UK Govt is a minority investor and AFAIK have no management input.**

Yes, of course, decisions for REL will be made by REL. However the placement of the spaceport is a decision that will be made in London. REL will go wherever the spaceport goes (not Scotland IMO: See above).

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Galactic Penguin SST on 05/11/2015 03:08 pm
Hmm I am surprised that you guys are thinking that local politics could have such an effect on the development of Skylon. In fact I would suggest not going down that road here again or I might need to start to intervene.  ;)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Nilof on 05/11/2015 03:38 pm
In contrast there is limited experience of pumped LH2/LO2 engines anywhere with 4 designs in the US (and the only production design dating from the 1960's) with 2 in Europe and 1 (IIRC) in Russia.


OTOH, looking only at engines that have actually flown on orbital flights or are very likely to do so in the near future, and ignoring hot tests:

US:
RL-10
J-2
SSME
RS-68
BE-3

Russia:
KVD-1
RD-0120 series
RD-0146 series
...and a ton of incredibly crazy experimental engines such as the 30 MPa chamber pressure RD-701 which have to count for something. Though the russians have avoided LH2 stages because of excellent non-cryogenic alternatives.


Europe:
HM-7 series
Vulcain series
Vinci

Japan:
LE-5 series
LE-7 series

India:
CE-7.5

China:
YF 73 and 75 series.

...imho, while LH2 is still a PITA as far as engine development is concerned, it is not necessarily more so than the decision to use a staged combustion cycle. Virtually everyone who has been concerned with improving the performance of their rockets rather than getting something into space period, has developed an LH2 expander or gasgen at some point.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 05/11/2015 09:21 pm
Expander cycle is good for upper-stage engines.  It has a maximum thrust, and it's not very high.  If you want high T/W and high Isp in a large engine that has to operate at sea level, some form of staged combustion is by far your best bet.

The SABRE seems to dodge a lot of the problems by taking advantage of the helium loop, which would be extra weight and complexity on a pure rocket but is essentially free here because they need it for the airbreathing mode.  This should significantly attenuate the issues with seals and metallurgy.  It's still not simple to develop, but if you add the cost of the SSME to the cost of the GE90 you do blow past REL's estimate...

Oh, wait just a second; that reminds me:

That's $360M to get to first working prototype.

Excuse me; that's £360M.  Everything else I said is fine.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 05/12/2015 10:51 pm
So it seems Jo Johnson is the new minister for Space ( and some other none spacey stuff) and as such seems likely to be involved in making some of the governments decisions regarding Skylon.
 
http://en.wikipedia.org/wiki/Jo_Johnson

On the one hand this may be seen as a bad thing as the man seemingly has no more than a high school science education  but I posit this may actually be a cunning plan as he has a background in finance as well as fluent French and an MBA from INSEAD. If the government was indeed interested in assisting Reaction Engines in forming a Skylon consortium with Airbus in the next four years that could be just the sort of background you might want in the minister in charge of helping to make it happen.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/13/2015 03:35 pm

http://en.wikipedia.org/wiki/Jo_Johnson
He is also Boris Johnsons's brother.

Time will tell if this is an asset or a liability.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Seer on 05/13/2015 07:48 pm
I notice that Skylon's fuselage is pinched at the middle where the payload bay is. I wonder why they decided not to use a wider payload bay of ~ 6 metres. How much of a payload penalty would that involve.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 05/13/2015 08:03 pm
It's a good guess this pinch is due to Area Rule influencing the design. (http://en.wikipedia.org/wiki/Area_rule)

So if you made the payload bay wider, the rest would widen proportionally too.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 05/13/2015 08:58 pm
I notice that Skylon's fuselage is pinched at the middle where the payload bay is. I wonder why they decided not to use a wider payload bay of ~ 6 metres. How much of a payload penalty would that involve.
It's a good guess this pinch is due to Area Rule influencing the design. (http://en.wikipedia.org/wiki/Area_rule)

So if you made the payload bay wider, the rest would widen proportionally too.

Yes, you have to keep in mind that Skylon is more of (but not "an") an aircraft than a standard launch vehicle so flying through the atmosphere to around Mach-5 makes aerodynamics important :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Seer on 05/13/2015 08:58 pm
I hadn't heard of that before. Well you learn something every day.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 05/14/2015 08:38 am
it would be good to have any kind of company update at this point. How is the work doing?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 05/14/2015 11:44 pm
it would be good to have any kind of company update at this point. How is the work doing?
This year they have gone crazy with the press updates, okay their been 3, which is three times more than we got in 2014.

http://www.reactionengines.co.uk/press_release.html (http://www.reactionengines.co.uk/press_release.html)

There were little updates and new pics and graphs and data release by the team at conferences but you will have to hunt them down by reading the threads on this website.

I'm not the only one that hopes when they get to the stage of testing their engine and components of the engine they will get a bit more open with us, perhaps with some nice pictures and videos. They could learn a thing or two about marketing from Space X.

The news section of their site haven't been undated since May 2014.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pmcaerospacefreighter on 05/18/2015 10:35 pm
I feel like they get a trickle of funding from the UK Govt, not enough to do anything much with it, but enough for the politicians to feel good about themselves.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/19/2015 12:00 am
I feel like they get a trickle of funding from the UK Govt, not enough to do anything much with it, but enough for the politicians to feel good about themselves.
REL are pretty good at making a (relatively) little go a long way.

The UK governments (roughly) $94m (over 2 years) may not sound much  but it's about 1/6 of their needed budget for the work they want to do. REL are extremely wary of any government gaining a controlling interest in the project and being able to dictate design or engineering decisions.

It is enough to allow them to make significant progress on the project.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pmcaerospacefreighter on 05/22/2015 05:03 pm
a single rocket launch (I assume they need to test their engines at altitude / hypersonic speed) would eat a lot of that.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hanelyp on 05/22/2015 05:28 pm
Ram jets have been operated with inlet and exhaust nozzles not greatly different from what a sabre engine would need.  Everything in between is not directly exposed to speed and altitude, accepting hot air at one end and producing hotter air at increased pressure at the other end.  A test of the sabre cycle core needs neither high speed not now pressure ambient environment.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/22/2015 06:57 pm
a single rocket launch (I assume they need to test their engines at altitude / hypersonic speed) would eat a lot of that.
Did no one tell you what happens when you "assume" things?

The pre cooler at the front of the engine decouples the air temperature (cryogenic) and velocity (about M0.5) from the ambient environment (up to 1000c and M5.5)

Pre coolers with this power to weight ratio and ability to do frost control have never been done before, which is why this had to be tested first as a failure would have been game over for the whole project.

What that means is (unlike the SCramjets) you don't need to put it on a rocket to test its performance, although putting it on some kind of test vehicle would be a bonus.

Most of this can be found on the technical documents on the REL website.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 05/22/2015 07:38 pm
They're not putting the engine on a test vehicle during this phase of development.  Once it's proven on the test stand (yes, it gets static thrust just fine because it has a turbocompressor), the rest of the ~$5B engine development program can commence, and that might conceivably involve sticking the engine on a test vehicle (which could easily be reusable as it's essentially an airplane).

Now, they have talked about using an internally-developed sounding rocket to test nozzle ideas, but that's not quite the same thing...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 05/23/2015 08:17 pm
As other have said below much of SABRE can be ground tested, but the nacelle - with its re-entry capable nose cone - is definitely novel, critical, and will need to be proven definitively early in development either through ground testing or in flight. REL had mentioned developing an NTV - a Nacelle Test Vehicle before now, but I don’t believe it’s in the current plan.

At first blush the nacelle/inlet looks reminiscent of other flown configurations such as that used on the SR-71: it’s axisymmetric with a translating shock cone. But the fact that it can close fully and successfully resist re-entry shock/plasma/thermal conditions is new.

I did wonder if one of the purposes of the Valkyrie project was to fly a nacelle model (in closed configuration) into re-entry-like conditions.

It seems to me there are a couple of challenges with the nacelle cone and louvres.

1] The louvres need to be thin to minimize drag during air-breathing (see the attached screen shot) of a REL animation. But this thinness limits the options for thermal protection: there’s no mass/structure to sink heat into, and not much room for active thermal control.

2] The sharp tip of the cone will receive the most severe heating as it’ll be close to the shock wave, and has little volume to sink heat back into. There may be room in the cone for active cooling. Or a more drastic departure would be to swap the actual cone for an aerospike, such as that used on the Trident ICBM. (see picture from http://en.wikipedia.org/wiki/Drag-resistant_aerospike below) During atmospheric ‘forward’ flight the spike is extended to form a simulated cone, but for re-entry it’s retracted leaving the cone blunt and so better suited to face the airflow (which now comes from below).

An aerospike could also be used to alleviate heating on the sharp fuselage nose as it will face similar heating issues.

(A pre-emptive note to JohnSmith19: Please don’t take these comments and suggestions to be my dismissal of the Skylon project as impossible. Thinking through engineering challenges like Skylon is a hobby of mine, and I share my thoughts in hopes of hearing corrections when I’m mistaken.)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/23/2015 10:48 pm
At first blush the nacelle/inlet looks reminiscent of other flown configurations such that on the SR-71: it’s axisymmetric with a translating shock cone. But the fact that it can close fully and successfully resist re-entry shock/plasma/thermal conditions is new.
True.
Quote
1] The louvres need to be thin to minimize drag during air-breathing (see the attached screen shot) of a REL animation. But this thinness limits the options for thermal protection: there’s no mass/structure to sink heat into, and not much room for active thermal control.
Like a lot of things in aeospace design "it depends." Skylon is so big what looks thin as a picture may be very substantial IRL. those louvres may actually be several cms thick.
Quote
2] The sharp tip of the cone will receive the most severe heating as it’ll be close to the shock wave, and has little volume to sink heat back into. There may be room in the cone for active cooling. Or a more drastic departure would be to swap the actual cone for an aerospike, such as that used on the Trident ICBM. (see picture from http://en.wikipedia.org/wiki/Drag-resistant_aerospike below) During atmospheric ‘forward’ flight the spike is extended to form a simulated cone, but for re-entry it’s retracted leaving the cone blunt and so better suited to face the airflow (which now comes from below).
Strictly Trident use an "aero disk" but the idea is very similar. Artillery shells are probably the main users of actual "aero spike" designs.
Quote
An aerospike could also be used to alleviate heating on the sharp fuselage nose as it will face similar heating issues.

(A pre-emptive note to JohnSmith19: Please don’t take these comments and suggestions to be my dismissal of the Skylon project as impossible. Thinking through engineering challenges like Skylon is a hobby of mine, and I share my thoughts in hopes of hearing corrections when I’m mistaken.)
REL have stated that the parts needed to resist peak heating loads they would be using a version of Reinforced Carbon Carbon. This has demonstrated service up to 3000c in the Shuttle nose area, with the right surface coating. DLR is one of REL's partners and they have substantial experience in RCC.

Hopefully glass reinforced silicon carbide will be adequate for the majority of both the fuselage, wings and nacelles, but there are alternatives.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Seer on 05/24/2015 05:06 pm
There are a number of new things that need to be developed. These include
1. The transitioning inlet
2. lox cooled chamber
3. heat exchangers, both the primary one and the high temperature silicon carbide one.
4. active thermal protections systems on the canards and winds and perhaps the inlet.
5. an aerodynamic configuration that can fly at hypersonic speeds (mach 5), re-entry and low landing speeds.
6. super lightweight tanks that are 1% of the mass of the propellant.

Having a high number of active systems increases the probability that one of them will fail during flight and also increases the maintenance and inspection burden between flights.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RobLynn on 05/24/2015 06:12 pm
There are a number of new things that need to be developed. These include
...
6. super lightweight tanks that are 1% of the mass of the propellant.
...

From memory for C1 configuration about 220Mg LOX+LH2 and ~1000m³ LH2 and 150m³ LOX,
http://selenianboondocks.com/2010/02/calculating-propellant-mass-sensitive-term/tankmers/
At very best cryogenic tanks are about 7kg/m³, so might be as little as 8Mg - say 4-5% of propellant mass.  Not realistic to target 25% of that.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 05/24/2015 07:44 pm
There are a number of new things that need to be developed. These include
...
6. super lightweight tanks that are 1% of the mass of the propellant.
...

I don't believe I've seen this 1% tank mass requirement before. Can you point us to a source? (Or is this your own assessment?)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Seer on 05/24/2015 10:25 pm
If you search for "skylon hotol" then go the top link on the second page of results. The tank is a balloon tank so that helps, but the hydrogen fraction is twice that of a normal vehicle and the tanks are split into two sets of tanks, which is more inefficient.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 05/25/2015 12:19 am
Those search terms revealed a number of interesting links (including videos of the Kerbal Space Program Skylon model that I'd not seen before) but not tank specs.

url?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Seer on 05/25/2015 12:50 am
Its a pdf, does this work? https://www.aiaa.org/WorkArea/DownloadAsset.aspx?id=14414
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: hkultala on 05/25/2015 01:20 am
Its a pdf, does this work? https://www.aiaa.org/WorkArea/DownloadAsset.aspx?id=14414

it's 1.27%.

And it's not a hard requirement, doubling the tank mass would hurt payload to LEO by only 2.7 tonnes.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 05/25/2015 01:34 am
I think we're all referring to the mass budget for the C1 design on pages 32-33? That shows 2,736kg budgeted for “main tankage, cryo Insulation & supports” to carry 216,630kg of propellant.

2.7 metric tonnes for tanks does sound light, but as hkultula points out more mass for the tank can be bought from elsewhere. Also, the C1 design/budget is at least one generation out of date (two if D1 is taken forward). The optimists among us will guess that later designs have wider margins.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/25/2015 02:49 am
Those search terms revealed a number of interesting links (including videos of the Kerbal Space Program Skylon model that I'd not seen before) but not tank specs.

url?
For those interested in tank design John Whiteheads paper makes very interesting reading.
http://www.osti.gov/scitech/servlets/purl/379977 (http://www.osti.gov/scitech/servlets/purl/379977)

Whitehead's team developed the first positive displacement pumps for what people now call micro launchers. Whitehead was (is?) looking at what it takes to build an SSTO 2 people could carry in the back of a pickup truck.

They note that "1%" tanks IE tank mass 1% of contents are possible over several orders of magnitude. LH2 is the exception but that's reduced to maybe 3% of contents mass. Tankage on LH2 vehicles is always highly deceptive. Those little red tanks on Skylon are much heavier than the huge LH2 tanks that fill most of the fuselage.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/25/2015 02:55 am
Its a pdf, does this work? https://www.aiaa.org/WorkArea/DownloadAsset.aspx?id=14414

it's 1.27%.

And it's not a hard requirement, doubling the tank mass would hurt payload to LEO by only 2.7 tonnes.
Doubtful. That rule applies when the tanks of the LV are virtually all of the dry mass (which for ELV stages they often are)

But for Skylon you'd need to figure that as a % of the dry mass, which IIRC is something like 46 tonnes, so it's 48/46 tonnes, IE about a 4% payload hit.

Tank mass is just a much smaller fraction of dry mass in Skylon than normal ELV's.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Seer on 05/25/2015 03:24 am
Its a pdf, does this work? https://www.aiaa.org/WorkArea/DownloadAsset.aspx?id=14414

it's 1.27%.

And it's not a hard requirement, doubling the tank mass would hurt payload to LEO by only 2.7 tonnes.


It is 1.27% but I rounded down because there are two sets of tanks, so its as difficult as 1%. The problem with saying only a 2.7 tonne hit to payload is that all the mass margins look light. The tanks are just the most blatant. What if the structure, TPS, secondary systems, engines etc are too?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/25/2015 04:00 am
Its a pdf, does this work? https://www.aiaa.org/WorkArea/DownloadAsset.aspx?id=14414

it's 1.27%.

And it's not a hard requirement, doubling the tank mass would hurt payload to LEO by only 2.7 tonnes.

It is 1.27% but I rounded down because there are two sets of tanks, so its as difficult as 1%. The problem with saying only a 2.7 tonne hit to payload is that all the mass margins look light. The tanks are just the most blatant. What if the structure, TPS, secondary systems, engines etc are too?
It's been a while since it was mentioned but Skylon is designed to AIAA guidelines with a 15% margin for hardware weight growth overall. However some of those will be tighter as there is quite a lot of data on horizontal cryogenic tanks for road and rail tankers. [EDIT Likewise large parts of the turbo machinery are well understood, so the margins for their design are narrower than they would have been say 40 or even 20 years ago. The less well understood sections have wider margins. ]
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Seer on 05/25/2015 04:02 am
Its a pdf, does this work? https://www.aiaa.org/WorkArea/DownloadAsset.aspx?id=14414

it's 1.27%.

And it's not a hard requirement, doubling the tank mass would hurt payload to LEO by only 2.7 tonnes.

It is 1.27% but I rounded down because there are two sets of tanks, so its as difficult as 1%. The problem with saying only a 2.7 tonne hit to payload is that all the mass margins look light. The tanks are just the most blatant. What if the structure, TPS, secondary systems, engines etc are too?
It's been a while since it was mentioned but Skylon is designed to AIAA guidelines with a 15% margin for hardware weight growth. However some of those will be tighter as there is quite a lot of data on horizontal cryogenic tanks for road and rail tankers.

road and rail tankers? Seriously?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 05/25/2015 09:29 am
It's been a while since it was mentioned but Skylon is designed to AIAA guidelines with a 15% margin for hardware weight growth overall.

You sure?  I know C1's truss structure had a 15% margin, and I know D1 was said to be designed with margins "consistent with" AIAA guidelines which implies at least 15% and probably more for the stage I tentatively judged the design to be at when I last attempted to figure this out, but I'm not aware of a concrete official number for the overall mass margin.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/25/2015 09:42 am
There are a number of new things that need to be developed. These include
Drawing from various REL presentations I'll mention when REL looked at a particular area.
Quote
1. The transitioning inlet
Ongoing since 2012. Inlets with moving centre bodies have been around since the late 50's.
Quote
2. lox cooled chamber
2010. Also the use of air cooling for the cooling while the vehicle is air breathing.
Quote
3. heat exchangers, both the primary one and the high temperature silicon carbide one.
Under study since 2002.
Quote
4. active thermal protections systems on the canards and winds and perhaps the inlet.
Not mentioned. However transpiration cooled rentry vehicles have flown in flight tests in the late 1970's and reports are available in the open literature.
Quote
5. an aerodynamic configuration that can fly at hypersonic speeds (mach 5), re-entry and low landing speeds.
Under development since the late 80's. Making  your fuselage circular, contouring it front to back for low supersonic drag and sticking the major point masses in the middle makes life a lot easier right from the first moment. Although cross range was not (AFAIK) a design driver it's given got most (if not all) of the Shuttles target (but never achieved) cross range.
Quote
6. super lightweight tanks that are 1% of the mass of the propellant.
Outside of LH2 a tank weighing 1% of its payload is not that difficult in the aerospace field.
Quote
Having a high number of active systems increases the probability that one of them will fail during flight and also increases the maintenance and inspection burden between flights.
Which logically makes the Wright Flyer the safest aircraft every built, as there's so little to wrong, right?  :)
Or maybe not.

You might like to look out the window at the leading edge of an airliner when it lands or takes off.

There's a lot of "active systems" in play during that period, and  if any of them move in the wrong way (or fail to move at all) you're going to have a  very bad day.

And yet every day millions of passengers risk their lives to those active systems without thinking about it.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pmcaerospacefreighter on 05/25/2015 04:31 pm

The pre cooler at the front of the engine decouples the air temperature (cryogenic) and velocity (about M0.5) from the ambient environment (up to 1000c and M5.5)


So what you are telling me is that the first Skylon prototype will take off from a runway and proceed onto test flights at regimes that progressively get closer and closer to space flight?
i would love to see that happen.  But it sounds like a great risk to test the whole airframe-engine combination over such large range of regimes, when we are not talking about a relatively simple rocket but a RBCC or whatever they're using.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: hkultala on 05/25/2015 08:21 pm
Its a pdf, does this work? https://www.aiaa.org/WorkArea/DownloadAsset.aspx?id=14414

it's 1.27%.

And it's not a hard requirement, doubling the tank mass would hurt payload to LEO by only 2.7 tonnes.
Doubtful. That rule applies when the tanks of the LV are virtually all of the dry mass (which for ELV stages they often are)

But for Skylon you'd need to figure that as a % of the dry mass, which IIRC is something like 46 tonnes, so it's 48/46 tonnes, IE about a 4% payload hit.

Tank mass is just a much smaller fraction of dry mass in Skylon than normal ELV's.

What rule are you talking about?

What goes to orbit is (dry mass + payload).

If either grows, another must shrink. By same absolute amount, not any percentage.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/25/2015 08:40 pm
road and rail tankers? Seriously?
One of the hallmarks of solid engineering is a focus on using advanced technology only where necessary.  A similar example would have been the pilots position for the SR71.  The vehicle set the standard for materials, engine cycles and sensors for at least a decade yet the core flying and engine controls were, AFAP, those of a standard twin jet aircraft of the time.

Despite 20+ years of work composite LH2 tanks still seem to have significant leakage levels.

If you don't need them, why use them?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Soundbite on 05/26/2015 02:36 pm
Hi All,

I dont' know if anyone noticed the patents that Reaction Engines has filed on 1 December 2014.  There are two that I can see but I haven't searched for anymore

They are found on page https://www.ipo.gov.uk/p-gcp?lastResult=40&perPage=10&filter=&sort=GCP+Request+Date (https://www.ipo.gov.uk/p-gcp?lastResult=40&perPage=10&filter=&sort=GCP+Request+Date)

The Details are found here https://www.ipo.gov.uk/p-ipsum/Case/ApplicationNumber/GB1318111.0 (https://www.ipo.gov.uk/p-ipsum/Case/ApplicationNumber/GB1318111.0) and here ://www.ipo.gov.uk/p-ipsum/Case/ApplicationNumber/GB1318108.6 (http://://www.ipo.gov.uk/p-ipsum/Case/ApplicationNumber/GB1318108.6) and then by clicking on the "Documents" link on the right hand side of these pages in the Window titled Select case view
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Soundbite on 05/26/2015 03:11 pm
Oops.... the last link address is faulty  :(

Try this https://www.ipo.gov.uk/p-ipsum/Case/ApplicationNumber/GB1318108.6 (https://www.ipo.gov.uk/p-ipsum/Case/ApplicationNumber/GB1318108.6) and I also found these https://www.ipo.gov.uk/p-ipsum/Case/ApplicationNumber/GB1318098.9 (https://www.ipo.gov.uk/p-ipsum/Case/ApplicationNumber/GB1318098.9) and https://www.ipo.gov.uk/p-ipsum/Case/ApplicationNumber/GB1318109.4 (https://www.ipo.gov.uk/p-ipsum/Case/ApplicationNumber/GB1318109.4) submitted on 12 January 2015
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 05/26/2015 07:42 pm
That's interesting news regarding the patents. I thought I heard somewhere that REL didn't want to patent the tech because they didn't want the information in the public domain. Is that memory of mine mistaken?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: momerathe on 05/26/2015 08:14 pm
I haven't gone over them in detail (patent-ese makes my eyes bleed), but one thing jumped out at me - there are two separate patents for two different engine configurations, and one of the says:

Quote
A rocket engine is provided. The engine comprises: a rocket combustion chamber [...] and and air-breathing combustion chamber [...]. [They] are configured to be operated indepedently

That's new, isn't it? judging from the diagrams, they're concentric, sharing the same nozzle. Poss connected to the Valkyrie work?

There also seems to be some changes to the cooling loops in this version from the diagrams we've seen before, but I haven't puzzled out what the practical difference is.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: momerathe on 05/26/2015 08:55 pm
here's (http://i.imgur.com/7lSH3Ak.gif) a half-assedly recoloured version of the diagram. the one things that jumps out at me is that the pre-burner.

The biggest difference I can spot is that in previously-described cycles, the cooled/compressed air is split between the nozzle and the pre-burner, and all the hydrogen flows through the pre-burner (i.e. the output from the pre-burner is hydrogen-rich). In this cycle it's the other way round. I'm not sure I could tell you what that signifies, though.

EDIT: ah-ha! looks like the frost-control cat is out of the bag.

Quote
an air intake [...] which includes a first heat exchanger for cooling incoming air, a water separator downstream of the first heat exchanger, a liquid oxygen injector downstream of the the water separator and a second heat exchanger downstream of the liquid oxygen injector. The injector reduces the airflow temperature so that water remaining in the airflow is converted to small dry ice crystals. [...] the liquid oxygen is used to reduce the temperature of the flow from between 5º and 13ºC to minus 50ºC or lower, such that a considerable amount of liquid oxygen needs to be used

hrm, interesting. how much is "considerable"? and how does this apply to self-ferry and/or Scimitar?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 05/26/2015 09:52 pm
That's interesting news regarding the patents. I thought I heard somewhere that REL didn't want to patent the tech because they didn't want the information in the public domain. Is that memory of mine mistaken?

I seem to remember that too. Elon Musk definitely said that. Did REL say it too? Hmmm... Someone here will answer this soon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/27/2015 06:10 am
here's (http://i.imgur.com/7lSH3Ak.gif) a half-assedly recoloured version of the diagram. the one things that jumps out at me is that the pre-burner.


EDIT: ah-ha! looks like the frost-control cat is out of the bag.
hrm, interesting. how much is "considerable"? and how does this apply to self-ferry and/or Scimitar?
I think the usual expression in patenese is "to those skilled in the art."  :)

The HX patent GB2519147 does go into considerable detail on how to solve the frost control problem.

One of the neatest parts is use of a solution of Methanol as anti freeze which gets sprayed and recollected as you move through the HX, allowing the Methanol to be recycled. This is a neat way to save on a non propellant consumable which over a full flight could be quite heavy.

Note using some LOX would be OK for SABRE but a definite problem for LAPCAT. Airliners don't (AFAIK) carry it at all. They tap the engine in flow for any air they need for cabin aircon.

Note 2 things about the HX patent.

They describe a way to solve this problem. It's probably what REL are using, but it might not be.

Anyone with any knowledge of mfg engineering will know that while what you have to make is described in quite a lot of detail it assumes you already have access to large amounts of specialized materials. In this application how you make it was as difficult a problem as what to make.

[EDIT A note about the British patent pages. They are in ascending order going down. The full patent document is usually the largest item at the end.  That's what's been patented.

My quick read of the "engine" patent is that the patent states the 3 diagrams show the same engine in different modes. It shows 2 combustion chambers because that's how the real SABRE works and the thing at the top is the "spill ramjet" used to reheat bypassed air as the engine speeds up. ]
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: momerathe on 05/27/2015 08:48 am
Look again- there are two engine patents describing different configurations (SABRE 3 vs SABRE 4 perhaps?). One is similar (but more detailed) to what we've seen before; the other describes the twin combustion chambers in addition to the bypass duct.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/27/2015 01:11 pm
Look again- there are two engine patents describing different configurations (SABRE 3 vs SABRE 4 perhaps?). One is similar (but more detailed) to what we've seen before; the other describes the twin combustion chambers in addition to the bypass duct.
My mistake. It was only when I ran over all the patent links I found the 2nd one, ending  -155 rather than -152.

Parallel combustion chambers and the ability to side step frost control.

This sounds like the Scimatar engine for the lapcat M5 airliner but I'm not quite sure why you need rocket combustion chambers at all.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: oddbodd on 05/28/2015 09:01 pm
Hi all, first time poster, long time lurker.

Seems there's more patents on the WIPO site that just recently got published that are also a little easier to read due to OCR and to refer back and forth to the drawings with:

1. 20150104316 TURBINE BLADES   US   16.04.2015
F01D 11/00   14296611   Reaction Engines Ltd.   Richard Varvill

2. 20150101308 ENGINE   US   16.04.2015
F02K 9/78    14296620   Reaction Engines Ltd   Alan Bond

3. 20150101333 ROTATIONAL MACHINE   US   16.04.2015
F02C 6/16     14296615   Reaction Engines Ltd   Alan Bond

4. 20150102129 MOUNTING ASSEMBLY   US   16.04.2015
F02K 9/84     14296618   Reaction Engines Ltd   Alan Bond

5. 20150101342 ENGINE   US   16.04.2015
F02C 7/228  14296624   Reaction Engines Ltd   Alan Bond

6. 20150101337 NOZZLE ARRANGEMENT FOR AN ENGINE   US   16.04.2015
F02K 9/97     14296628   Reaction Engines Ltd   Alan Bond

7. 20150101334 HEAT EXCHANGERS   US   16.04.2015
F02C 7/141   14296603   Reaction Engines Ltd   Alan Bond

Just do a search on "reaction engines ltd" including the quotes at https://patentscope.wipo.int/search/en/search.jsf

From what I've read and understood (IANARS - I am not a rocket scientist) I've understood the frost control (#7) to be the following:
Incoming air cooled down to a little above freezing passes over several layers of the thin tubes. Some methanol is mixed into the air flow around here. It then passes over a set of thicker tubes (Fig 13 &14) wrapped with a mesh that catches 95% of the liquid/moisture. It then passes through the remaining thin tubes and any remaining water/methonal gets crystalised as the air drops to the -150 C. Something I don't fully understand (methonol? very low water content?) causes the formation of crystals rather than the furry frost that would otherwise block the heat exchanger. I think there is then a recovery and recycling of the captured methanol to re-inject into the airflow. Figure 19D shows the thin and thick tubes, and 520 on the image shows the air travelling inwards.

To contradict momerathe, the section he quotes is from the background section and describes a different patent. I don't think REL's solution injects liquid oxygen at all, but I haven't read it in it's entirety, so apologies if I'm wrong.

In #2, #5 and #6 where the engines and nozzle arrangements are described and shows two nested nozzles. I think this may be a novel alternative to an expansion deflection rocket. The inner nozzle is for full on rocket mode. In air breathing mode the outer nozzle is used, and the rocket nozzle acts like the expansion deflection pintel.

Hope that was a useful first post  :)

[Edit] Rereading it seems the crystallization happens through sublimation, although surely that's the wrong word? Sublimation = Solid -> Gas, don't they mean Deposition = Gas -> Solid
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: oddbodd on 05/28/2015 09:07 pm
 :-[ Missed the bit where JS19 had already picked up and ID'd the use of methanol. Please ignore me trying to sound clever on that bit.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: zodiacchris on 05/28/2015 09:21 pm
Welcome Oddbodd! Good first post indeed  8)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: oddbodd on 05/28/2015 09:45 pm
#4 the mounting assembly patent, Fig 2. Do my eyes deceive me, or is that a drag resistant aerospike? First time I've seen that in a drawing/image. I think someone might have mentioned it as a possible option previously though.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 05/28/2015 11:05 pm
Looks like one of their really old pictures of SABRE (see Figure 6 in Varvill & Bond (2003) (http://www.reactionengines.co.uk/tech_docs/JBIS_v56_108-117.pdf)).  The newer models all have a simple conical forebody.  Doesn't mean that's what they're going with, of course...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: oddbodd on 05/28/2015 11:24 pm
In #2, #5 and #6 where the engines and nozzle arrangements are described and shows two nested nozzles. I think this may be a novel alternative to an expansion deflection rocket. The inner nozzle is for full on rocket mode. In air breathing mode the outer nozzle is used, and the rocket nozzle acts like the expansion deflection pintel.

Hmmm. Actually read it properly now, and it's even more interesting. It actually translates. The smaller inner nozzle cone moves back (relative to direction of travel), creating an annular flow for separate air breathing combustion chambers arranged around the central axis. On transition to rocket mode the smaller nozzle cone moves forward, with the larger truncated nozzle cone section extending the smaller one. In this mode the rocket combustion chamber of the smaller nozzle cone is used. But the point stands that it is using the smaller nozzle cone as a pintel to create the annular flow for higher efficiency across altitudes.  8)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: oddbodd on 05/28/2015 11:45 pm
I really need to go to bed  :D

http://worldwide.espacenet.com/searchResults?ST=singleline&locale=en_EP&submitted=true&DB=worldwide.espacenet.com&query=%22reaction+engines+ltd%22 (http://worldwide.espacenet.com/searchResults?ST=singleline&locale=en_EP&submitted=true&DB=worldwide.espacenet.com&query=%22reaction+engines+ltd%22)

Mostly looks like overlap, with the same 7 US ones I posted before, a couple of additional GB ones, but probably overlap the US ones, and one WO one for engine ducts.

Looks like they're all originally from back in 2013, although it seems the international stuff was applied for mid last-year.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Seer on 05/28/2015 11:53 pm
Anyone want to have a guess as to how much helium is carried? I tried to estimate it from various RE mass budgets but could never get a particularly precise number. Is it possible to estimate it from first principles? I.e knowing the pump pressure and thrust of the main engines?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: oddbodd on 05/29/2015 12:32 am
Looks like one of their really old pictures of SABRE (see Figure 6 in Varvill & Bond (2003) (http://www.reactionengines.co.uk/tech_docs/JBIS_v56_108-117.pdf)).  The newer models all have a simple conical forebody.  Doesn't mean that's what they're going with, of course...

Ah yes, that's long before I'd even heard of REL/Skylon etc. Now I think about it maybe someone mentioned it disrupting flow into the engine, which would explain it's absence in newer images.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/31/2015 07:59 am
:-[ Missed the bit where JS19 had already picked up and ID'd the use of methanol. Please ignore me trying to sound clever on that bit.
Welcome to the forum. Your patent list has brought a lot to the party and gives much food for thought.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/31/2015 08:03 am
Anyone want to have a guess as to how much helium is carried? I tried to estimate it from various RE mass budgets but could never get a particularly precise number. Is it possible to estimate it from first principles? I.e knowing the pump pressure and thrust of the main engines?
The key issue would be what is the peak amount of heat (set by the air mass and temperature) you have to move around the cycle and at what temperatures and pressure do you have to work with.

Probably possible from first principles and the data in the Skylon C1 trajectory spreadsheet.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: FutureSpaceTourist on 05/31/2015 08:58 am
That's interesting news regarding the patents. I thought I heard somewhere that REL didn't want to patent the tech because they didn't want the information in the public domain. Is that memory of mine mistaken?

I seem to remember that too. Elon Musk definitely said that. Did REL say it too? Hmmm... Someone here will answer this soon.

Yes, Reaction Engines have always said they would never apply for UK ones because of what happened with HOTOL (ie patents ended up restricted to military on national security grounds). I guess they've decided that to protect themselves from potential U.S. involvement/applications they need US ones?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: FutureSpaceTourist on 05/31/2015 10:32 am
Oops.... the last link address is faulty  :(

Try this https://www.ipo.gov.uk/p-ipsum/Case/ApplicationNumber/GB1318108.6 (https://www.ipo.gov.uk/p-ipsum/Case/ApplicationNumber/GB1318108.6) and I also found these https://www.ipo.gov.uk/p-ipsum/Case/ApplicationNumber/GB1318098.9 (https://www.ipo.gov.uk/p-ipsum/Case/ApplicationNumber/GB1318098.9) and https://www.ipo.gov.uk/p-ipsum/Case/ApplicationNumber/GB1318109.4 (https://www.ipo.gov.uk/p-ipsum/Case/ApplicationNumber/GB1318109.4) submitted on 12 January 2015

Ok, so my previous post is obviously out of date - I hadn't caught up enough on this thread!

I'm guessing the legal situation in the UK has changed and/or the more favourable support from the UK government (£60M funding) has made Reaction Engines confident enough now to patent. It's great that there is now a lot more technical info in the public domain, if only I had enough engineering expertise to understand it  :D
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: momerathe on 05/31/2015 12:16 pm
either way - now the patents are out there, the clock is ticking.. I just hope this means they're confident they can execute on their roadmap.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/31/2015 03:41 pm
either way - now the patents are out there, the clock is ticking.. I just hope this means they're confident they can execute on their roadmap.

I don't think REL have every really doubted their ability to build SABRE provided a)The pre cooler worked as expected and b) The could get the funding.

The pre cooler has now been extensively tested and worked as expected. Progress milestones then depend on their getting the necessary funding when it's needed.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 05/31/2015 04:33 pm
I think these patent applications are an interesting development. Why have REL decided to submit patents when previously they said they wouldn't?

My guess is that it may have had to do with securing funding. Perhaps a major potential investor said they'd only invest if they felt that they could protect their investment from being upstaged by copy-cat designs ie have the technology protected by patents.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 05/31/2015 08:33 pm
I think these patent applications are an interesting development. Why have REL decided to submit patents when previously they said they wouldn't?

My guess is that it may have had to do with securing funding. Perhaps a major potential investor said they'd only invest if they felt that they could protect their investment from being upstaged by copy-cat designs ie have the technology protected by patents.

Another aspect is that they have to start thinking about who will make the bits. If they can't make absolutely everything themselves then it may be hard to hide all their secrets. Inference might be enough to help someone guess in the end.

Another aspect is that the more people they hire, the harder it has to be to ensure that no secrets could ever leak out.  Someone leaves the company, having stumbled across something they should not know, for example.  What can you do in such a case?

Another aspect is that the more interest they generate, the more attention they attract, the more some other clever people may be able to work out what they are doing anyhow.

Finally, I can't imagine that REL haven't been the targets of some degree of espionage.   Would any country with strategic interests in space not at least want to know if they were onto a good idea? The patents will at least make it clear what REL really did invent so that copycats can be sanctioned in some way.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Soundbite on 05/31/2015 09:38 pm
Reaction Engines has just posted a news update on Mark Thomas joining the Board http://www.reactionengines.co.uk/news_updates.html (http://www.reactionengines.co.uk/news_updates.html)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/01/2015 10:33 am
Another aspect is that they have to start thinking about who will make the bits. If they can't make absolutely everything themselves then it may be hard to hide all their secrets. Inference might be enough to help someone guess in the end.
In some ways the simplest motivation is that it can be done at all encourages people to try finding out how.
Quote
Another aspect is that the more people they hire, the harder it has to be to ensure that no secrets could ever leak out.  Someone leaves the company, having stumbled across something they should not know, for example.  What can you do in such a case?
Other business have been built on trade secrets. Whitehead's torpedoes worked on them. The disk drive business was built on the ability to coat the platters with a magnetic layer. The precise details of this process used by each mfg have always been a closely guarded set of techniques, as both the chemistry and the morphology of the layer is critical. typically a new entrant would hire key staff from existing players to acquire this information.
Quote
Another aspect is that the more interest they generate, the more attention they attract, the more some other clever people may be able to work out what they are doing anyhow.

Finally, I can't imagine that REL haven't been the targets of some degree of espionage.   Would any country with strategic interests in space not at least want to know if they were onto a good idea? The patents will at least make it clear what REL really did invent so that copycats can be sanctioned in some way.
Logically yes.

Practically the most effective protection has probably been that people have been obsessed with SCRamjets, to the point they simply don't think it's possible for this to work, and  if it is, to deliver the performance claimed.

While that was the consensus I doubt anyone could be made to try intelligence collection.

That position should be changing and I hope REL will plan accordingly.

I'll remind people that it's one thing to explain what has to be done. It's quite another to explain how it's done. 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: aameise9 on 06/04/2015 04:39 pm
Reaction Engines has just posted a news update on Mark Thomas joining the Board http://www.reactionengines.co.uk/news_updates.html (http://www.reactionengines.co.uk/news_updates.html)

Bump.  Perhaps some of our Brits would care to comment?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 06/05/2015 05:17 am
Reaction Engines has just posted a news update on Mark Thomas joining the Board http://www.reactionengines.co.uk/news_updates.html (http://www.reactionengines.co.uk/news_updates.html)

Bump.  Perhaps some of our Brits would care to comment?

I don't know anything special but there's a more extended biography of him here:

http://aerosociety.com/Events/Event-List/1577/Rolls-Royce-future-developments-in-engine-technology

Rolls Royce has been making people redundant recently, though from what I read these are precision machining jobs.  I do also remember reading that they planned to spend a bit less on research after something of a "splurge" recently.  So based on those two things you could make a guess that some interesting work could have been cancelled and SABRE development might seem attractive compared to what's left at Rolls. I know absolutely nothing about it and am speculating utterly.

The other speculation one could make is that he is being sent out as part of a kind of "deal" a bit like the Microsoft-Nokia thing with Stephen Elop. I only mention it because I experienced it.  I don't know whether that would be a cheering thing or not. At least you can say that RE includes some people who have worked for Rolls Royce so presumably they know each other at least by reputation and that increases the possibility of things happening.

Here is a quote of the link above:
Quote
Mark Thomas, CEng, FRAeS

Mark is Chief Engineer for Technology and Future Programmes in the Rolls-Royce Civil Large Engines Business. He leads the Engineering teams responsible for the exploration and concept design of next generation propulsion systems; also the execution of system level demonstrators to deliver innovative technologies meeting future product requirements.

In 2014 Mark will celebrate 25 years with Rolls-Royce, joining the Company in 1989 as a sponsored Undergraduate trainee before completing an Engineering degree at Queens’ College, Cambridge University.

Mark’s career started in the Rolls-Royce Defence Aerospace Business and he has completed a variety of Engineering and Management roles located in the UK and Germany.

Notable roles have included Chief Development Engineer for the EJ200 (Typhoon) Engine, Programme Executive for UK Defence Research and Technology, Chief Engineer for the EJ200 (Typhoon), RB199 (Tornado) & Adour (Hawk/Jaguar) engine programmes, and Technical Director of the Eurojet Turbo GmbH consortium based in Munich.

As a Chief Engineer in Defence, Mark was responsible for the support of around 3,000 engines worldwide with 25 Military Operators ranging from the US Navy to Royal Australian Air Force.

In 2009 Mark moved to the Civil Aerospace Business in Derby to take up the role of Chief Engineer for the Trent 900 (Airbus A380), leading the team during an especially challenging three year period for the programme, working closely with Airbus and Airline Customers.

Mark is a Chartered Engineer, Fellow of the Royal Aeronautical Society and also a Governor of a flourishing Engineering Academy. He mentors a number of engineers in Rolls-Royce and is a key member of the Rolls-Royce Senior Engineering Leadership team.

Mark is married with two teenage sons and one daughter and lives in Leicestershire. Outside work he enjoys skiing, travel and reading.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: oddbodd on 06/07/2015 01:49 am
The other speculation one could make is that he is being sent out as part of a kind of "deal" a bit like the Microsoft-Nokia thing with Stephen Elop. I only mention it because I experienced it.  I don't know whether that would be a cheering thing or not. At least you can say that RE includes some people who have worked for Rolls Royce so presumably they know each other at least by reputation and that increases the possibility of things happening.
Nokia had serious problems with timely delivery and was in need of a good shake-up. However Stephen Elop was either a trojan with a not-so-secret mission to devalue Nokia to the point where Microsoft could buy it for peanuts, or he was a grotesquely incompetent charlatan being paid obscene amounts for negative results! Under his tenure every metric went drastically down; revenue, profit, unit sales, share price. For this he was rewarded with $18m bonus and a new VP position at Microsoft. Even now, after the purchase by the 800-lb gorilla and the associated benefits that brings, I still rarely see Nokia/Windows phones in the wild here in Germany/UK.

I think Bond and co. are experienced enough (and wary enough) to avoid a debacle like Nokia's happening to REL. However I don't think they (Bond & Thomas) overlapped at RR so I sincerely hope there isn't some kind of predatory nature to Mark Thomas' appointment. It would be tragic for some Machiavellian skulduggery to strangle the Skylon in utero. Skylon may fail to fly, but if so that should be because very clever people failed to make the science work; not because some manager looks at some numbers in a spreadsheet, and decides to burn the place to the ground to "rescue" it.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 06/07/2015 08:12 am

The other speculation one could make is that he is being sent out as part of a kind of "deal" a bit like the Microsoft-Nokia thing with Stephen Elop. I only mention it because I experienced it.  I don't know whether that would be a cheering thing or not. At least you can say that RE includes some people who have worked for Rolls Royce so presumably they know each other at least by reputation and that increases the possibility of things happening.
Nokia had serious problems with timely delivery and was in need of a good shake-up. However Stephen Elop was either a trojan with a not-so-secret mission to devalue Nokia to the point where Microsoft could buy it for peanuts, or he was a grotesquely incompetent charlatan being paid obscene amounts for negative results! Under his tenure every metric went drastically down; revenue, profit, unit sales, share price. For this he was rewarded with $18m bonus and a new VP position at Microsoft. Even now, after the purchase by the 800-lb gorilla and the associated benefits that brings, I still rarely see Nokia/Windows phones in the wild here in Germany/UK.

I think Bond and co. are experienced enough (and wary enough) to avoid a debacle like Nokia's happening to REL. However I don't think they (Bond & Thomas) overlapped at RR so I sincerely hope there isn't some kind of predatory nature to Mark Thomas' appointment. It would be tragic for some Machiavellian skulduggery to strangle the Skylon in utero. Skylon may fail to fly, but if so that should be because very clever people failed to make the science work; not because some manager looks at some numbers in a spreadsheet, and decides to burn the place to the ground to "rescue" it.

The whole thing is pretty baseless speculation and the Nokia/Microsoft business was done to death at the time in the relevant forums without digging it up again here.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: aameise9 on 06/07/2015 08:42 am

The whole thing is pretty baseless speculation and the Nokia/Microsoft business was done to death at the time in the relevant forums without digging it up again here.

The main message seems to me that Mark Thomas is a very senior and very serious engineer who knows how to build engines ...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 06/07/2015 12:43 pm


The whole thing is pretty baseless speculation and the Nokia/Microsoft business was done to death at the time in the relevant forums without digging it up again here.

The main message seems to me that Mark Thomas is a very senior and very serious engineer who knows how to build engines ...

And surely that's all that matters.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 06/07/2015 02:26 pm
Star One
**The whole thing is pretty baseless speculation and the Nokia/Microsoft business was done to death at the time in the relevant forums without digging it up again here.**

He brought it up, not to discuss the Nokia/Microsoft issue itself, but just to highlight a point. He didn't say that the unsubstantiated speculation about Stephen Elop was true, just that he hoped that it wasn't something that might happen at REL with Mark Thomas.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 06/07/2015 04:07 pm


The whole thing is pretty baseless speculation and the Nokia/Microsoft business was done to death at the time in the relevant forums without digging it up again here.

The main message seems to me that Mark Thomas is a very senior and very serious engineer who knows how to build engines ...

And surely that's all that matters.

No. The boss, unlike the chief engineer, also needs to be able to sell engines for a profit.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/07/2015 05:56 pm
And surely that's all that matters.
No. The boss, unlike the chief engineer, also needs to be able to sell engines for a profit.
And raise a very significant amount of funding.

And drive the formation of the airframe consortium.

Without a single wealthy investor who can eliminate part of this funding issue fund raising is a pretty serious part of running a company like this to deliver the results within a reasonable time frame.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 06/07/2015 06:17 pm

And surely that's all that matters.
No. The boss, unlike the chief engineer, also needs to be able to sell engines for a profit.
And raise a very significant amount of funding.

And drive the formation of the airframe consortium.

Without a single wealthy investor who can eliminate part of this funding issue fund raising is a pretty serious part of running a company like this to deliver the results within a reasonable time frame.

Well I trust their judgement on this when it comes to their choice of senior personnel.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 06/08/2015 11:48 am
The other speculation one could make is that he is being sent out as part of a kind of "deal" a bit like the Microsoft-Nokia thing with Stephen Elop. I only mention it because I experienced it.  I don't know whether that would be a cheering thing or not. At least you can say that RE includes some people who have worked for Rolls Royce so presumably they know each other at least by reputation and that increases the possibility of things happening.
Nokia had serious problems with timely delivery and was in need of a good shake-up. However Stephen Elop was either a trojan with a not-so-secret mission to devalue Nokia to the point where Microsoft could buy it for peanuts, or he was a grotesquely incompetent charlatan being paid obscene amounts for negative results! Under his tenure every metric went drastically down; revenue, profit, unit sales, share price. For this he was rewarded with $18m bonus and a new VP position at Microsoft. Even now, after the purchase by the 800-lb gorilla and the associated benefits that brings, I still rarely see Nokia/Windows phones in the wild here in Germany/UK.

I think Bond and co. are experienced enough (and wary enough) to avoid a debacle like Nokia's happening to REL. However I don't think they (Bond & Thomas) overlapped at RR so I sincerely hope there isn't some kind of predatory nature to Mark Thomas' appointment. It would be tragic for some Machiavellian skulduggery to strangle the Skylon in utero. Skylon may fail to fly, but if so that should be because very clever people failed to make the science work; not because some manager looks at some numbers in a spreadsheet, and decides to burn the place to the ground to "rescue" it.

well, I must say I really like nokia/windows phones! they are basically a mobile terminal of my laptop.

besides, i m not sure about the relation with RR. there is one thing that REL needs, and it's capital. Possibily, cheap friendly capital. RR has it, quite a lot. And RR's people know pretty well how to raise capital. That's the single most important thing for REL now, and it's on it that the game is played. So a bit of engagement from RR wouldn't be necessarily negative I believe.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 06/14/2015 01:31 pm
I've changed from saying - the answer is Skylon, now what's the question (for about 30 years) - until more more recent times (and on these threads) when I still say this, but... Elon Musk...

When's European Space going to see reality slapping it hard in the face, bite the bullet and figure it's **** or bust? ULA are going to be decimated by SpaceX and they're not the only ones. China and Japan are reacting now too.

http://www.wsj.com/articles/spacex-and-the-russian-rocket-mess-1434149145

ESA haven't got a BFR (Mars mega-rocket) in planning anyway so it's not as if doing Skylon hinders any of their plans. Moreover if the technology works who knows what leads that will give European aerospace?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/15/2015 06:55 am
I've changed from saying - the answer is Skylon, now what's the question (for about 30 years) - until more more recent times (and on these threads) when I still say this, but... Elon Musk...

When's European Space going to see reality slapping it hard in the face, bite the bullet and figure it's **** or bust? ULA are going to be decimated by SpaceX and they're not the only ones. China and Japan are reacting now too.
Part of it is the way the European system differs from the US model.

Since there was only one European launcher to begin with they have never had the painful issue of phasing out an LV design.

Keep in mind Ariane 5 has been commercially successful in the global launch market where Delta IV has not, and they are both 2 stage LH2/LO2 designs with SRBs, with engines designed and built specifically for the vehicle. Ariane even uses common bulkhead tanks, which some people believe are very difficult to do (which they are, unless you read up on the extensive literature NASA generated working out how to make it work).

Large corporations react slowly to (potentially) radical change.

I think it's interesting that Airbus started their recovery project in 2010, five years ago. That suggests someone thought it prudent to have something in the bag in case this happened.

You also need to look at it from the Airbus PoV. In 2011 SX releases a video showing full recovery of an F9. By 2014 Musk is saying that's not economically possible (why it's not remains unanswered) so at least some of the senior management can claim "See, he was bluffing, they are not serious." Shotwells comments on the NATO presentation, when she stated a comm sat launch to GEO is about $100m (basically what Arianespace charge with a rideshare) would also support their argument.

I consider this a "doctrine of impotence" as RV Jones put it. It's comforting and dangerously complacent.

The trouble is Skylon has a lot of risk associated with it, relative to a a nice, well understood architecture like the TSTO ELV. That's important for pan European designs incorporating a lot of multiple governments money. Right now there isn't even a "Skylon making company" for ESA to pass money to. Likewise there is no entity you can contact and say "I'd like to buy a Skylon, what's it cost and how big a down payment do you need?"

You might think of A6 as the "comfort" design for the next generation European LV.  :(

ESA faces a mighty problem. It's under pressure to reduce it's form of "assured access" payments to Arianespace. A6 is designed to be cheaper to make and sell and be easier to find payloads for as you don't need to do rideshares to make its price reasonable.

But if A6 is not cheap enough or lacks performance it will loose out. OTOH F9's GTO performance is to the low end of flights so the question is should Europe be worried now?

If you look behind the SX PR machine can't put the bigger comm sats into GTO and that combination is where the money is. It also explains why SX is keen to get into NSS, as that's a captive market for US only LV's.

The trouble with this rather comforting world view is that it ignores Musks intent and that while F9 is not quite big enough to get large comm sats to orbit FH will be.

So ESA can't justify making SABRE/Skylon it's primary for the NGLV, but based on REL's expansion (a 3600x increase in funding over the last 15 years) and it's ability to deliver on each of its goals close to time and budget it would seem possible that it could supply some funding on an ongoing basis.


Title: News
Post by: JN on 06/15/2015 11:17 am
News update on the website: Rocket Testing Underway

- PRESS RELEASE -

Monday 15 June 2015

Reaction Engines Ltd. have begun their latest round of rocket engine testing in Westcott, UK.

The SABRE engine requires a novel design of the rocket engine’s thrust chamber and nozzle to allow operation in both air-breathing and rocket modes, as well as a smooth transition between the two. The Advanced Nozzle project is demonstrating the feasibility of this concept and represents a significant technology development effort towards the SABRE demonstrator engine.

The test engine, which has been successfully fired 15 times during its initial commissioning phase in spring 2015, incorporates several new technologies including a 3D printed, actively cooled propellant injector system. Aerodynamic data collected from the firings is being used to validate in-house computational modelling and advance the nozzle design. The test campaign is being operated by Airborne Engineering Ltd in Westcott, Buckinghamshire. Operations are planned to continue throughout 2015, including long duration burns and tests investigating the transition between air- breathing and rocket operation planned for later in the year.

Dr Helen Webber, Reaction Engines’ Project Lead for the Advanced Nozzle Programme, commented: “This experimental engine is an important step into a new era of propulsion and space access. We are using it to test the aerodynamics and performance of the advanced nozzles that the SABRE engine will use, in addition to new manufacturing technologies such as our 3D-printed injection system.

The testing of new propulsion technology has required close work with our partners at Airborne Engineering, in order to make a test rig that can simulate the unique and demanding range of conditions required to put this engine through its paces. Despite being much smaller than SABRE, this engine is still the largest bi-propellant engine to be tested at Westcott for over thirty years, and it is exciting to see the resurgence of Westcott as the centre for UK rocket propulsion research and development. The next few months will see us running the engine for much longer periods in order to explore the transition between the air-breathing and rocket modes of the SABRE’s flight - an important and challenging part of powering Skylon into space.”

There's a video as well: http://www.reactionengines.co.uk/vid_stoicfiring.html

Enjoy!
Title: Re: News
Post by: t43562 on 06/15/2015 11:57 am
- PRESS RELEASE -

Monday 15 June 2015

Reaction Engines Ltd. have begun their latest round of rocket engine testing in Westcott, UK.

I shouldn't complain because news is great to have :-) but ..... I can't resist a quick moan about the way the url for news updates doesn't have a link for each specific story.  i.e. it's www.reactionengines.co.uk/news_updates.html for everything.

This does make it difficult reposting stories sometimes as various other system such as facebook expect a link to link to the same text next week as it does this week.  It's just generally difficult because after some time any link will be wrong.

</moan>

Anyhow it's great news :-)

I wonder if STOIC is still an expansion-deflection nozzle?  I assume so.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: JN on 06/15/2015 12:38 pm
Point taken  - I'm working on some major fixes for the website. It'll be a while yet, but watch this space! (excuse the pun...)
Title: Re: News
Post by: john smith 19 on 06/15/2015 02:20 pm
I wonder if STOIC is still an expansion-deflection nozzle?  I assume so.
According to the REL update at the IAC (IAC-13,D2,4,6,x19609) STOIC is the hot fire version of the STRIDENT cold flow test test chamber, itself developed from the initial STRICT chamber and CFD models calibrated from STRICT tests. All of this is around E/D nozzles.

So yes an E/D nozzle, but incorporating a)Active cooling. AFAIK all  AE engines have been heat sink designs made from big billets of Copper. b) Probably including both air and O2 cooling to simulate the switch over in flight.

Making this the first tri-propellant thrust chamber test in the UK  :)

I've always had a thing about "transitions" in systems. My instinct has always been the air/LOX shift in the chamber and things like the final sealing of the inlet by the spike and its sealing rings would be the place where "unknown unknowns" would be prone to lurk in this system to bite you.

These tests look like they will tackle that issue head on.

If I'm reading the press release correctly STOIC will therefor do a full duration burn (a little over 16 mins) starting in air/H2 and shifting to O2/H2 around 5 mins in.

Sadly I don't think this will include altitude effects but will supply more detailed data to upgrade the CFD for the ground test SABRE.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 06/16/2015 12:33 am
Excellent news. Good to hear that things are hotting up at REL  :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Kharkov on 06/16/2015 06:15 am
I seem to recall it being said that the addition of Expansion/Deflection nozzles to SABRE engines means that the required distance to reach takeoff speed, and so the maximum length of the runway allowing abort capability will be reduced to less than the max length of 5,500mtrs, which to my mind has always been a problem. Not a project-stopping problem but a significant PITA.
Would anyone care to speculate, if we take it as read that Expansion/Deflection nozzles are used, what the standard takeoff/max runway length would be?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/16/2015 10:49 am
I seem to recall it being said that the addition of Expansion/Deflection nozzles to SABRE engines means that the required distance to reach takeoff speed, and so the maximum length of the runway allowing abort capability will be reduced to less than the max length of 5,500mtrs, which to my mind has always been a problem. Not a project-stopping problem but a significant PITA.
Would anyone care to speculate, if we take it as read that Expansion/Deflection nozzles are used, what the standard takeoff/max runway length would be?
Hempsell mentioned this on a Space Show, but I can't recall which episode.

IIRC this could cut the take off run by 400-500m. As this at full GTOW that would be the part of the runway that has to be extra reinforced.

REL have talked of the runway as a $Bn investment so cutting 1/9 of the heaviest section should be good for saving $90-100m for a new build.

I'll remind people that is only for a full orbit capable runway. A Skylon could be based in its home country at much shorter (lower loading) runways at it'll be 150 tonnes lighter when in air breathing out to Kourou, before LH2 refuel and LO2 on load.
Title: Re: News
Post by: john smith 19 on 06/18/2015 05:34 pm
The SABRE engine requires a novel design of the rocket engine’s thrust chamber and nozzle to allow operation in both air-breathing and rocket modes, as well as a smooth transition between the two. The Advanced Nozzle project is demonstrating the feasibility of this concept and represents a significant technology development effort towards the SABRE demonstrator engine.
Most interesting.

Will the test engine have a name?

"SABRE demonstrator engine" seems a bit unwieldy, or is it so close to a flight model SABRE it's more like SABRE v0.9?
Title: Re: News
Post by: t43562 on 06/19/2015 05:02 am
Will the test engine have a name?

"SABRE demonstrator engine" seems a bit unwieldy, or is it so close to a flight model SABRE it's more like SABRE v0.9?

"sabre" I imagine.

or "sABRE" :-)  or . . . . . . dare I say it . . . . .. "Light ...er ... SABRE?"
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 06/19/2015 02:58 pm
It's not a full SABRE, so perhaps it might be referred to as a SABRE lite;
.........or even as t43562 suggests, a lite SABRE.   ::)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 06/19/2015 08:39 pm
Here's an article on REL by Parabolic Arc

http://www.parabolicarc.com/2015/06/19/reaction-engines-begins-rocket-tests/#more-55597
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 06/23/2015 05:59 pm
I have been reading over on the pprune forum (military aviation) several posts in praise of the use of a ski jump to launch the Harrier and the upcoming F35-B.   "It's like having a free 1.5km runway in the sky".

A question was asked about why they are not used on land as well - and here is a video of that happening:

https://vimeo.com/lmaeronautics/review/131439135/07c088ad82

The answer was generally that they weren't so critically important when there was enough runway space as you do find on land.  They are also inconvenient if you want to use the runway to land in the opposite direction (if I understand correctly).

I was just thinking about whether Skylon could make use of a ramp?

I couldn't immediately see if this had been discussed before - perhaps long ago or with different words than I searched for.  Sorry if I missed it.

Presumably the gradient would have to be much lower for such a long vehicle and perhaps the landing gear might not survive it. 
I am sure there must be other objections but I thought it might make the very expensive runway a bit shorter.

I suppose to be fair it wouldn't remove the need for a long of free space after the end of the runway for a Skylon to pass over as it builds up to flying speed but you would not, perhaps, have to build anything on it.

I suppose there is also the thought that Skylon doesn't have any kind of thrust vectoring and I'm not sure how much that affects the usefulness of a ramp.  Wikipedia tells me that the Su-33 doesn't appear to use vectoring but I have seen the ramps on Russian carriers.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/23/2015 06:29 pm
I suppose there is also the thought that Skylon doesn't have any kind of thrust vectoring and I'm not sure how much that affects the usefulness of a ramp. 
I thin k you'll find that SABRE does do thrust vectoring, but on the whole engine, rather than something smaller.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 06/23/2015 08:57 pm
I thought it was just the chambers/bells that were supposed to gimbal.  And not by much; this isn't a Harrier here...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Kharkov on 06/24/2015 05:07 am
@t43562

I think you'll find that Skylon's takeoff speed is around Mach 0.5. I'm not an engineer but I really wouldn't want to hit even a very modest ski jump at anything like that speed...

Having said that however, would it help matters - shorten the takeoff run a bit & get Skylon into the air quicker - if at around Mach 0.45, the forward undercarriage extended its length by another metre or so, raising the nose and increasing the angle of attack on the wings?

I suspect you'd need to gimbal the thrust somewhat to avoid melting bits of the runway...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/24/2015 09:42 am
I thought it was just the chambers/bells that were supposed to gimbal.  And not by much; this isn't a Harrier here...
It's a tricky point. Early US engines (and I think the Russians?) pivoted their thrust chambers only, but the US started pivoting their whole engines from quite early on, presumably feeling pivoting about the fairly low pressure feed lines from the tanks were going to be a lot easier than moving the TC, need flexible couplings capable of staying leak proof at 10s (100's for the SSME) of atms.

You're right about the gimbal angles, IIRC even the Shuttle only did +/- 7.5 deg on any axis, which is well within the range of a flexure bearing (which can be made very strong)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 06/24/2015 10:49 am
@t43562

I think you'll find that Skylon's takeoff speed is around Mach 0.5. I'm not an engineer but I really wouldn't want to hit even a very modest ski jump at anything like that speed...

I'm also a layman but from what I read, the aircraft leaves the ramp at less than flying speed - otherwise the ramp wouldn't actually be serving any purpose.  It's the fact that it has space and time (thanks to the vector given to it by the ramp) to accelerate in the air and reach flying speed without it's wheels having to be on tar that gives you the advantage of a shorter runway.

M 0.5 is about 600kmh and googling leads me to believe that the Harrier stalls at roughly 270kmh.  I suppose the harrier number is rather a rough guess and would be very variable depending on takeoff weight anyhow.  Nevertheless it's indicative of the relative difference - maybe Skylon need to travel about 2X faster.

Perhaps any ramp would have to be correspondingly 2X more gentle and would then need to be very very long and very very strong and would end up being more expensive than the extra runway.  It's gradient would also be limited by how much Skylon could tip before the tail touched the ground and as you said the effect of the engines on the runway.
 

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 06/24/2015 06:10 pm
The real killer for this idea is that a large proportion of the runway is for abort contingency, where Skylon cuts off the engines and slams on the (water cooled) brakes.

Bang (crash, bang, wallop) goes the intact abort option when you fall off the end of the ramp while braking...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/24/2015 06:59 pm
Given Reaction Engine's approach of having as few unconventional technologies as possible, I suspect launch ramps are something that may not be considered for the first wave.
Welcome to the site.

Yes, I've never heard of a land runway with ski jump. It's a clever idea but aircraft carriers have (essentially) a cliff the aircraft falls off if takeoff fails. That's not the case for normal airports.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 06/24/2015 09:01 pm
The real killer for this idea is that a large proportion of the runway is for abort contingency, where Skylon cuts off the engines and slams on the (water cooled) brakes.

Bang (crash, bang, wallop) goes the intact abort option when you fall off the end of the ramp while braking...

One of the great things about the internet is the way that you get to talk to all sorts of people you'd never otherwise meet.  I asked John Farley, one of the most famous Harrier test pilots, about it on pprune and his objection was that the T/W had to be over 0.85 roughly.   My very dodgy guess at Skylon's T/w is 0.26.

As for abort.....obviously that does present a serious problem but I suppose it might be worth trying to think about that some other way if a ramp was actually worthwhile in the first place.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Asteroza on 06/24/2015 11:23 pm
Possible arrangement of a ramped runway is an otherwise long and flat conventional runway with an overrun extension leading up an embankment to an elavated (relative to main runway elevation) runout extended overrun area exclusively for Skylon. If the embankment change in elevation is roughly equivalent to traditional 100ft obstacle clearance spec and is a appropriate upward curve for the expected speed, normal airplanes will have no issue (though pilots will get creeped out by the ground following them up). The annoyance is the overrun area is where approach lighting equipment is normally located (and the inner marker beacon?) so how one would set that up flush in the overrun is a bit of a problem. That achieves the hump with no cliff dropoff, and no downhill component for a inserted hump in a runway complicating emergency braking.

In retrospect, I suppose the humped aspect could be better achieved with a single contiguous runway with the hump near Skylon Vto, so the overall runway looks like a flattened S shape. This avoids the overrun design issues. Many existing runways have non-flat profiles due to local topography (and cost cutting avoiding the earthworks to build a flat runway), though I think of those, most tend to have a V profile? Though that depends on local terrain being helpful to keep costs down.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 06/25/2015 09:29 pm
My very dodgy guess at Skylon's T/w is 0.26.

C1 was around 0.45-0.47 during the takeoff roll, and peaked (for the airbreathing segment) at roughly 0.8 just past Mach 2.  The D revision has some substantial differences from the C designs, including larger wings and a more efficient engine cycle, so there might be some modest changes in those numbers.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 06/26/2015 07:59 pm
I've been thinking about the differences between the SABRE 3 and SABRE 4 cycles since the patents became available to read.
I think it's interesting that where as the former was designed as an integrated engine which was an excellent rocket and an adequate air breather the later seems to be a much less integrated engine designed to be an excellent rocket and and a good air breather and that this disintegration of the engine modes has resulted in a much more flexible design.

Historically all attempts at combined cycle engines seem to be about finding the right balance between performance and integration of different engine cycles and it seems REL have moved in the direction of more performance and less integration.

An interesting result of this is that where as previously the SABRE engine could be said to be not much good for anything other than SSTO that's no longer strictly true for the SABRE 4 cycle. Its equivalence ratio of 1.2 is not far off Scimitar's EQ of  0.7959 and the patent allows for a variant to run at the same EQ by adding another recuperation stage and lower pressure combustion chambers, further the only thing that is shared with the rocket mode is the nozzle so it would seem possible to easily remove all the pure rocket components to make a pure air breathing SABRE variant with reasonable fuel consumption only without the high life cycle and subsonic efficiency of Scimitar.

This begs the question, given the USAF interest in SABRE, have REL  decided in order increase their addressable market  to develop a duel purpose engine design that both satisfies their design needs for SSTO but also allows for an easily achievable variant that satisfies USAF desire for hypersonic flight and when they talk about SABRE, is this the SABRE they're talking about?   
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 06/26/2015 10:29 pm
... disintegration of the engine ...
Is that a phrase REL have used in their patent? Hope no-one takes it out of context! (like I just did...  :) )
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/27/2015 07:39 am
This begs the question, given the USAF interest in SABRE, have REL  decided in order increase their addressable market  to develop a duel purpose engine design that both satisfies their design needs for SSTO but also allows for an easily achievable variant that satisfies USAF desire for hypersonic flight and when they talk about SABRE, is this the SABRE they're talking about?
No. REL were clear the cycle they described to the USAFRL was the same one given to the Von Karman Institute  so the USAF could compare their results with a 3rd party. That's the SABRE 3.

SABRE IV's stated improvement is reduction in LH2 during airbreathing. REL were also clear if you want an air breathing engine their LAPCAT work is the way to go. USAFRL do not appear to have been interested in this work.

The idea that somehow hypersonic cruise is like arrested launch seems to come from the SCRamjet community.

The only part of an (RLV) launch that hypersonic cruise resembles is the re-entry.

The technical term for a rocket LV that is not accelerating during engine burn is crashing  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 06/27/2015 09:25 am
... disintegration of the engine ...
Is that a phrase REL have used in their patent? Hope no-one takes it out of context! (like I just did...  :) )
No, perhaps not the best word, but engine no longer shares a fuel delivery system,  rocket chambers or preburner betweeen modes.

This begs the question, given the USAF interest in SABRE, have REL  decided in order increase their addressable market  to develop a duel purpose engine design that both satisfies their design needs for SSTO but also allows for an easily achievable variant that satisfies USAF desire for hypersonic flight and when they talk about SABRE, is this the SABRE they're talking about?
No. REL were clear the cycle they described to the USAFRL was the same one given to the Von Karman Institute  so the USAF could compare their results with a 3rd party. That's the SABRE 3.
But the collaboration is ongoing, and ongoing REL is working on SABRE 4 so the USAF is interested in SABRE 4 and part of that is :
 
Quote
  the proposed work will include investigation of vehicle concepts based on a SABRE derived propulsion system
Now couldn't that be describing a SABRE 4 derived engine such as I suggested might be possible based on the patents.

SABRE IV's stated improvement is reduction in LH2 during airbreathing. REL were also clear if you want an air breathing engine their LAPCAT work is the way to go. USAFRL do not appear to have been interested in this work.

The idea that somehow hypersonic cruise is like arrested launch seems to come from the SCRamjet community.

The only part of an (RLV) launch that hypersonic cruise resembles is the re-entry.

The technical term for a rocket LV that is not accelerating during engine burn is crashing  :(

The difference between Scimitar and SABRE is that the former has a fan added for high efficiency subsonic cruise  performance and :

Quote
The main difference between the Scimitar engine and the well investigated SABRE spaceplane engine is the design lifetime, 15,000hours compared to 50 hours. Apart from this, the Scimitar requirement is alleviated by reduced mass sensitivity relative to SABRE.

As has been discussed previously for a military engine for a highly specialized vehicle short lifetimes are more acceptable and the need for subsonic cruise on a hypersonic bomber is perhaps debatable. Other than that are you arguing Scimitar itself is a bad idea?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 06/27/2015 12:17 pm
@lkm
AFAIK REL had the SABRE 4 concept in mind long before the USAF collaboration. Like JS19 says, I think the USAF had access to the SABRE 3 cycle and not the SABRE 4 cycle, but I could be wrong about that.

BTW, I think de-integration might be a better descriptor  :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 06/27/2015 03:38 pm
These chaps sound like the sort of people who would need a Skylon if it was available:


Quote
OneWeb satellite operator eyes huge rocket campaign
http://www.bbc.com/news/science-environment-33268180
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 06/27/2015 03:51 pm
@t43562
The OneWeb consellation of satellites is planned to be operational by 2020, far too early for Skylon. That time-frame aside however, I still doubt Skylon would be a good fit for launching the proposed satellites. Each is reported to weigh only 125kg and work at an altitude of 1200km. Both weight and altitude don't match with skylon. Even with orbital boosters I think the satellites would be too small to form part of an economic cargo.

However, this is a good example of how a successful skylon programme doesn't negate the need for other types of operators. The saying 'horses for courses' will still be true in 2025.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 06/27/2015 04:28 pm
@t43562
... That time-frame aside however, I still doubt Skylon would be a good fit for launching the proposed satellites. Each is reported to weigh only 125kg and work at an altitude of 1200km. Both weight and altitude don't match with skylon. Even with orbital boosters I think the satellites would be too small to form part of an economic cargo.

I presume they have been designed to fit the launchers available to them.  Perhaps they would not look the same if Skylon was on the scene.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 06/27/2015 10:31 pm
Yes, no doubt designed partially with existing launch capability in mind (and partially with the need to fulfil job specifications).

But agreed of course, increased launch capability as provided by skylon (if successful) will open up a whole new ball-game in space access and will change how people view space in terms of reliability of launch, flexibility of launch, vastly reduced lead-in times (on the order of days if needed) and perhaps other stuff that we haven't considered yet.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/28/2015 11:03 am
@t43562
The OneWeb consellation of satellites is planned to be operational by 2020, far too early for Skylon. That time-frame aside however, I still doubt Skylon would be a good fit for launching the proposed satellites. Each is reported to weigh only 125kg and work at an altitude of 1200km. Both weight and altitude don't match with skylon. Even with orbital boosters I think the satellites would be too small to form part of an economic cargo.
The trip to GEO is planned to use the Skylon Upper Stage. That's designed to carry about a 6500Kg payload to GTO.

1200Km is about 1/35 of GEO. That suggests an SUS could carry a pretty big number of them. With no changes that would 48 sats. I'd guess at 1/35 the altitude you could increase the quite a bit.

But now the timetable does not look feasible for Skylon to be used.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: banjo on 06/28/2015 01:31 pm
Do senior representatives of REL, Airbus and Rolls Royce meet every other Sunday for a beef dinner and a pint?  I'd like to think so.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 06/28/2015 01:35 pm
JS19
**1200Km is about 1/35 of GEO. That suggests an SUS could carry a pretty big number of them. With no changes that would 48 sats. I'd guess at 1/35 the altitude you could increase the quite a bit.**

Yes, but each has to be inserted into a different position and thus each would require their own booster. If you look at the manual for skylon there appears to be room for just one booster load, and that load would be of considerably great weight than each of these satellites. Not that skylon couldn't launch them, just that they wouldn't be the target market.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 06/28/2015 08:06 pm
JS19
**1200Km is about 1/35 of GEO. That suggests an SUS could carry a pretty big number of them. With no changes that would 48 sats. I'd guess at 1/35 the altitude you could increase the quite a bit.**

Yes, but each has to be inserted into a different position and thus each would require their own booster. If you look at the manual for skylon there appears to be room for just one booster load, and that load would be of considerably great weight than each of these satellites. Not that skylon couldn't launch them, just that they wouldn't be the target market.

Being a layman is fun - I can suggest all sorts of impossible things and claim I don't know any better :-).  Imagine that you had a SUS-like booster which carried multiple satellites.   Could it, perhaps, boost itself to a slightly lower orbit than 1200km and let a small electric thruster on each satellite itself finish the job?   I'm a bit unclear about whether 2 objects in the same shaped orbit but with a slight altitude difference would move relative to one another - playing Kerbal Space program leads me to think they do move.   If that's right then the dispenser in it's lower orbit would be able to release satellites at intervals which would boost themselves into the 1200km orbit.  It might be at 1199km so the boost would only be the extra speed needed to in increase the radius by 1km.   Such a small difference might mean it took months to deploy but the dispenser could perhaps fill a band for the cost of 1 Skylon  launch.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/29/2015 12:05 am
Being a layman is fun - I can suggest all sorts of impossible things and claim I don't know any better :-).  Imagine that you had a SUS-like booster which carried multiple satellites.   Could it, perhaps, boost itself to a slightly lower orbit than 1200km and let a small electric thruster on each satellite itself finish the job?   I'm a bit unclear about whether 2 objects in the same shaped orbit but with a slight altitude difference would move relative to one another - playing Kerbal Space program leads me to think they do move.   If that's right then the dispenser in it's lower orbit would be able to release satellites at intervals which would boost themselves into the 1200km orbit.  It might be at 1199km so the boost would only be the extra speed needed to in increase the radius by 1km.   Such a small difference might mean it took months to deploy but the dispenser could perhaps fill a band for the cost of 1 Skylon  launch.
You might like to look at the 1st generation Orbcomm satellites.

Most were deployed by single Pegasus XL launches to populate a ring of 8 satellites, each being designed like a pizza so they could be stacked together.

While the bus could supply some separation IIRC most was done by the satellites small thrusters or simple gravitational drift.

Orbcomm was one of 3 early 90's constellations (Globalstar and Iridium being the others) that actually got built. IIRC it offered the least bandwidth but was the only one that made (or came close to making) a profit. Something this new generation of constellation promoters (and their investors) might like to keep in mind.

Incidentally 1200Km is inside the Van Allan radiation belt and above the GPS constellation.

The first reduces air drag (which is actually the largest residual force on satellites below 1000Km) but raises the radiation exposure levels, so either the electronics cook faster or you have to spend mass on shielding, making them less capable, or you replace more frequently. How much more frequently would be a key design decision to trade replacement versus making them tough enough to survive as long as less exposed satellites.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Asteroza on 06/29/2015 12:38 am
JS19
**1200Km is about 1/35 of GEO. That suggests an SUS could carry a pretty big number of them. With no changes that would 48 sats. I'd guess at 1/35 the altitude you could increase the quite a bit.**

Yes, but each has to be inserted into a different position and thus each would require their own booster. If you look at the manual for skylon there appears to be room for just one booster load, and that load would be of considerably great weight than each of these satellites. Not that skylon couldn't launch them, just that they wouldn't be the target market.

Being a layman is fun - I can suggest all sorts of impossible things and claim I don't know any better :-).  Imagine that you had a SUS-like booster which carried multiple satellites.   Could it, perhaps, boost itself to a slightly lower orbit than 1200km and let a small electric thruster on each satellite itself finish the job?   I'm a bit unclear about whether 2 objects in the same shaped orbit but with a slight altitude difference would move relative to one another - playing Kerbal Space program leads me to think they do move.   If that's right then the dispenser in it's lower orbit would be able to release satellites at intervals which would boost themselves into the 1200km orbit.  It might be at 1199km so the boost would only be the extra speed needed to in increase the radius by 1km.   Such a small difference might mean it took months to deploy but the dispenser could perhaps fill a band for the cost of 1 Skylon  launch.

Dwell time for an upper stage maneuver bus might be the issue here. If you are targeting 6-10 sats per orbital plane, the basic options are one bus per plane or one bus for the whole operation, but a single bus means a much longer duration of operations (which implies electric with a substantial solar array). Going to a slightly lower orbit and using precession to swap planes might be viable, assuming final orbit raising via electric thrusters on the sats is reasonable, as a means to reduce dwell time.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/29/2015 12:14 pm
Dwell time for an upper stage maneuver bus might be the issue here. If you are targeting 6-10 sats per orbital plane, the basic options are one bus per plane or one bus for the whole operation, but a single bus means a much longer duration of operations (which implies electric with a substantial solar array). Going to a slightly lower orbit and using precession to swap planes might be viable, assuming final orbit raising via electric thrusters on the sats is reasonable, as a means to reduce dwell time.
Except the bus in this case would be the SUS, which is currently spec'd at having a 10 use life time and would be recovered by the Skylon for return to Earth and refueling.

A completely reusable system changes deployment options quite a lot, especially given the target payload (125Kg?) for a single unit is much smaller than the target for a much bigger single payload to a much higher orbit.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Asteroza on 06/30/2015 12:11 am
Dwell time for an upper stage maneuver bus might be the issue here. If you are targeting 6-10 sats per orbital plane, the basic options are one bus per plane or one bus for the whole operation, but a single bus means a much longer duration of operations (which implies electric with a substantial solar array). Going to a slightly lower orbit and using precession to swap planes might be viable, assuming final orbit raising via electric thrusters on the sats is reasonable, as a means to reduce dwell time.
Except the bus in this case would be the SUS, which is currently spec'd at having a 10 use life time and would be recovered by the Skylon for return to Earth and refueling.

A completely reusable system changes deployment options quite a lot, especially given the target payload (125Kg?) for a single unit is much smaller than the target for a much bigger single payload to a much higher orbit.

Which implies cluster deployers (AKA corncob upper stages) will not be based on the currently envisioned cryogenic fueled SUS, but more like a SUS-like electric tug. So cSUS and eSUS variants?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/30/2015 09:46 am
Which implies cluster deployers (AKA corncob upper stages) will not be based on the currently envisioned cryogenic fueled SUS, but more like a SUS-like electric tug. So cSUS and eSUS variants?
I don't think so. The dispenser is part of the payload. It's designed to fit on the front of the upper stage.

In Skylon's case the US sits in the payload but it's still the upper stage.

I don't see anyone who they are booked with announcing an ion drive upper stage. That's more of a "space tug" concept.

I would expect they will deploy like most of these constellation concepts. Upper stage burns AFAP, gravity drift if needed and satellite thrusters if absolutely necessary.

BTW IIRC the latest Skylon User Manual has a description of deploying an ion drive comm sat. In it the SUS deploys it about 5000 Km (above the radiation belt) and avoids the "radiation crockpot" effect.

No I don't think a specific ion drive US will be necessary.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 07/06/2015 03:46 pm
Today is out the new UK Space Humanflight strategy.

There is an indirect, but very very clear reference to Skylon. It appears it will have a dedicated section in the 2015 Space Technology Strategy (yet to be published I believe):

"Likewise, the development of  spaceplane technology in the UK would  complement these activities, and this will  be considered by the Agency in its national  space technology strategy." (p.10)

here the link

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/442462/Space_Environments_and_Human_Spaceflight_Strategyv2.pdf

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Soundbite on 07/10/2015 10:46 am
An article in Aviation Week Titled "Reaction Engines Reveals Secret Of Sabre Frost Control Technology" stated that Richard Varvill spoke at the American Institute of Aeronautics and Astronautics International Space Planes and Hypersonics conference and explained how the frost control system works.

Mark Thomas also explained why they finally patented the frost control mechanism.  He said  “The trigger for patenting was the awareness that to execute this program we are going to have to involve other companies. You can’t keep trade secrets very long in that situation, so it is better to be protected formally and legally on the clever stuff.”

At the end of the article it states that:

The company is developing  the Sabre engine principally for the Skylon single-stage-to-orbit spaceplane. But the propulsion system and its pre-cooler technology are attracting wider interest for potential aircraft and two-stage launch vehicle applications

You can read the article here https://awin.aviationweek.com/ArticlesStory.aspx?id=4ae664e7-3da0-4832-9827-03895f066bb3
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 07/10/2015 03:51 pm
**The trigger for patenting was the awareness that to execute this program we are going to have to involve other companies. You can’t keep trade secrets very long in that situation, so it is better to be protected formally and legally on the clever stuff**

That was going to be the only reasonable outcome. Other companies they're hoping to work with obviously didn't want the risk of doing business with REL unless there was legal protection on the core technology. Now the question is which companies are REL in negotiation with?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 07/10/2015 04:41 pm
well, not sure of names, but it must have these characteristics

- being a big player with a history in airframes
- being interested in space launch business
- being credible when developing new projects
- being stack with cash, or eventually being so well known to being able to raise cash at favourable interest rates.

I would bet on RR, Boeing or LM, but who knows?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/10/2015 07:14 pm
well, not sure of names, but it must have these characteristics
I would bet on RR, Boeing or LM, but who knows?
Originally REL were only talking about the pre cooler but their skills seem to be growing and their confidence at executing the whole design.

This would not be competition to RR, since they don't make hybrid air breathing rocket engines.

LM are solely government contractors. For Europe the formation of a division of Astrium would be the logical way to go.

The issue for REL remains some way of signing up future customers to purchase a vehicle from another company that has not been formed yet which can be passed to that company.

That definitely sounds like a problem in economics or international law.

[EDIT Read the Av Week article. So it does use Methanol in a counter flow arrangement, starting at th back with (presumably) near pure Methanol and using the dynamic pressure to force it forward to lower and lower pressure stages.

Obviously a tricky process to get right but one that seems to have proved very effective.
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/10/2015 08:10 pm
well, not sure of names, but it must have these characteristics
I would bet on RR, Boeing or LM, but who knows?
Originally REL were only talking about the pre cooler but their skills seem to be growing and their confidence at executing the whole design.

This would not be competition to RR, since they don't make hybrid air breathing rocket engines.

LM are solely government contractors. For Europe the formation of a division of Astrium would be the logical way to go.

The issue for REL remains some way of signing up future customers to purchase a vehicle from another company that has not been formed yet which can be passed to that company.

That definitely sounds like a problem in economics or international law.

[EDIT Read the Av Week article. So it does use Methanol in a counter flow arrangement, starting at th back with (presumably) near pure Methanol and using the dynamic pressure to force it forward to lower and lower pressure stages.

Obviously a tricky process to get right but one that seems to have proved very effective.

LM are the ones who would be most interested for their aviation projects as they tick a lot of the right boxes. I don't see why LM's focus on government contracts is an issue for you?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: AnalogMan on 07/10/2015 11:04 pm
Apart from a batch of UK patents published on 15 April 2015 (ten of them) there have also been 3 more published within the last 4 weeks.  All 13 patents were originally lodged on 11 Oct 2013.  I didn't see these new ones mentioned yet.

17 June 2015
Patent GB2521113 (https://www.ipo.gov.uk/p-ipsum/Case/PublicationNumber/GB2521113)
Applicant: Reaction Engines Limited (Incorporated in the United Kingdom)
Title: Heat exchanger
Date Lodged: 11 October 2013
Inventors: Bond, Alan and Varvill, Richard

17 June 2015
Patent GB2521114 (https://www.ipo.gov.uk/p-ipsum/Case/PublicationNumber/GB2521114)
Applicant: Reaction Engines Limited (Incorporated in the United Kingdom)
Title: Heat exchanger
Date Lodged: 11 October 2013
Inventors: Bond, Alan and Varvill, Richard

01 July 2015
Patent GB2521588 (https://www.ipo.gov.uk/p-ipsum/Case/PublicationNumber/GB2521588)
Applicant: Reaction Engines Limited (Incorporated in the United Kingdom)
Title: Turbomachine with radially compressed blades
Date Lodged: 11 October 2013
Inventor: Varvill, Richard

Copies attached.  List of published UK patents since 2010 can be found at this link (https://www.ipo.gov.uk/p-pj/p-pj-ukapppub.htm?startYear=2010&startMonth=July&startDay=28th+-+6323&endYear=2015&endMonth=July&endDay=8th+-+6581&filter=%22reaction+engines%22&perPage=100&sort=Publication+Date).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 07/10/2015 11:15 pm
Well, plenty of technical specifications there. As the Dutch say - the monkey's out of the sleeve now. :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/11/2015 04:46 pm
LM are the ones who would be most interested for their aviation projects as they tick a lot of the right boxes. I don't see why LM's focus on government contracts is an issue for you?
AFAIK LM make no commercial products. All they do is a)Government contract work b)National security systems c) Weapon systems.

This means they are good at a)Filling in procurement paperwork and b)Lobbying governments and their support staffs to get funded and c)Lobbying governments and their support staffs to get extended funding.

All of those are skills, they're just not actually very useful when it comes to making stuff.

IOW Their idea of "profit" is nothing to do with a commercial entities. The nearest LM come to space launch is they supplied the Delta IV half of the ULA product portfolio.

AFAIK the Delta IV has never launched a non USG satellite (IE not NASA, DoD or some other "Administration"). Where private companies have gone with a ULA vehicle it's the Atlas, or the go with some other supplier.

That is a very bad choice if you want to engage with world wide customers and have tight cost and schedule, which REL need to do.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 07/11/2015 05:18 pm
For completeness sake we should mention Lockheed made the L-1011 TriStar passenger jet - operated by British Airways, and with engines developed for it by Rolls Royce. But that was a long time ago, and not a roaring success...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/11/2015 05:53 pm

LM are the ones who would be most interested for their aviation projects as they tick a lot of the right boxes. I don't see why LM's focus on government contracts is an issue for you?
AFAIK LM make no commercial products. All they do is a)Government contract work b)National security systems c) Weapon systems.

This means they are good at a)Filling in procurement paperwork and b)Lobbying governments and their support staffs to get funded and c)Lobbying governments and their support staffs to get extended funding.

All of those are skills, they're just not actually very useful when it comes to making stuff.

IOW Their idea of "profit" is nothing to do with a commercial entities. The nearest LM come to space launch is they supplied the Delta IV half of the ULA product portfolio.

AFAIK the Delta IV has never launched a non USG satellite (IE not NASA, DoD or some other "Administration"). Where private companies have gone with a ULA vehicle it's the Atlas, or the go with some other supplier.

That is a very bad choice if you want to engage with world wide customers and have tight cost and schedule, which REL need to do.

Well if you're the U.S. & want REL's technology for military use then I would think that's precisely what makes LM a strong choice.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 07/11/2015 05:54 pm
ok, so we can exclude LM from the picture. Who else should be dropped?
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/11/2015 06:25 pm
ok, so we can exclude LM from the picture. Who else should be dropped?

Why are you assuming this technology is only for commercial/civilian purposes because if you are then you're being very, very naive.

I'd put reasonable money on this seeing use in the military long before it has commercial use.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 07/11/2015 06:46 pm
We're in danger of talking past each other here. There are at least two points being argued for, which are fairly distinct:

1] If REL is looking for an airframer to build Skylons, Lockheed Martin is not an obviously good choice.
2] If REL is looking to license some of its recently patented technologies (multiple), then Lockheed Martin is a likely customer as they deal in products that could potentially benefit from them, e.g. military jet/UAV/cruise missiles, etc.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 07/11/2015 10:58 pm

1.  AFAIK LM make no commercial products. All they do is a)Government contract work b)National security systems c) Weapon systems.

2.  This means they are good at a)Filling in procurement paperwork and b)Lobbying governments and their support staffs to get funded and c)Lobbying governments and their support staffs to get extended funding.

3.  IOW Their idea of "profit" is nothing to do with a commercial entities. The nearest LM come to space launch is they supplied the Delta IV half of the ULA product portfolio.

4.  AFAIK the Delta IV has never launched a non USG satellite (IE not NASA, DoD or some other "Administration"). Where private companies have gone with a ULA vehicle it's the Atlas, or the go with some other supplier.


Wrong on all points

1.  They do commercial comsats.   The A2100 satellite bus has been used for many comsats.  The LM500 spacecraft bus was used for the initial Iridium constellation.

2.  Completely unsubstantiated and nonsense

3. LM supplied the Altas V which has commercial contracts and had many for Atlas II.

4.  Delta IV launched Eutelsat W5.  The GOES launches on Delta IV were completely commercial.  They were converted Delta III launches from a Hughes block buy.  The gov't had no role in the procurement.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 07/12/2015 07:28 am

1.  AFAIK LM make no commercial products. All they do is a)Government contract work b)National security systems c) Weapon systems.

2.  This means they are good at a)Filling in procurement paperwork and b)Lobbying governments and their support staffs to get funded and c)Lobbying governments and their support staffs to get extended funding.

3.  IOW Their idea of "profit" is nothing to do with a commercial entities. The nearest LM come to space launch is they supplied the Delta IV half of the ULA product portfolio.

4.  AFAIK the Delta IV has never launched a non USG satellite (IE not NASA, DoD or some other "Administration"). Where private companies have gone with a ULA vehicle it's the Atlas, or the go with some other supplier.


Wrong on all points

1.  They do commercial comsats.   The A2100 satellite bus has been used for many comsats.  The LM500 spacecraft bus was used for the initial Iridium constellation.

2.  Completely unsubstantiated and nonsense

3. LM supplied the Altas V which has commercial contracts and had many for Atlas II.

4.  Delta IV launched Eutelsat W5.  The GOES launches on Delta IV were completely commercial.  They were converted Delta III launches from a Hughes block buy.  The gov't had no role in the procurement.

I read that the Altas V was developed for a US Airforce program.    Are they the type of company to start a risky new venture that doesn't have a big guaranteed customer such as the government?  e.g. there are people who say that about BAE.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 07/12/2015 10:56 am
ok, so we can exclude LM from the picture. Who else should be dropped?

Why are you assuming this technology is only for commercial/civilian purposes because if you are then you're being very, very naive.

I'd put reasonable money on this seeing use in the military long before it has commercial use.

I am not assuming that it is only for civilian purposes. However, I believe it will originally be for civilian purposes. But I might be wrong.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RotoSequence on 07/12/2015 11:01 am
I am not assuming that it is only for civilian purposes. However, I believe it will originally be for civilian purposes. But I might be wrong.

The US Air Force is one of the first companies to bankroll the technology. Unless I'm mistaken, it could be an enabling technology for hypersonic, air breathing aircraft with conventional turbine engines. If that's true, the first applications will almost certainly be military in nature.
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/12/2015 11:10 am
I am not assuming that it is only for civilian purposes. However, I believe it will originally be for civilian purposes. But I might be wrong.

The US Air Force is one of the first companies to bankroll the technology. Unless I'm mistaken, it could be an enabling technology for hypersonic, air breathing aircraft with conventional turbine engines. If that's true, the first applications will almost certainly be military in nature.

Yes I think we need to separate one thing from another. Technology licensed to the airforce & Skylon's build by commercial private industry.

I apologise in retrospect my OP was rather too hot headed.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 07/12/2015 11:16 am
why don't we open a poll on who will be the airframer?  :) it could be fun to see who's the most guessed.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: momerathe on 07/13/2015 10:57 am
EADS would be at the top of the list, I would have thought. Probably the only non-US* aerospace company capable of executing a development program of that size.



* ITAR
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 07/13/2015 05:36 pm
Nice posts JCRM. Welcome to the thread.

If anyone is interested the wingspan of the Skylon D1 is 26.818m - for comparison, a bit less than an original 737 at 28.35m (both sources Wikipedia).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/14/2015 06:46 am
For completeness sake we should mention Lockheed made the L-1011 TriStar passenger jet - operated by British Airways, and with engines developed for it by Rolls Royce. But that was a long time ago, and not a roaring success...
A long time ago.  :(

They (like BAe) pretty much divested themselves of any stuff that doesn't have some part of a government (preferably the US, but as long as they have plenty of cash) a long time ago.

Do  you want that as the core contractor for a time critical project to replace a significant part of their business?

If you wonder what LM would be like on this I have a simple example.

The X33 programme.

Swallowed every cent of both the development and test budgets and still failed to build a vehicle.

On that basis BAe would be a better fit.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: QuantumG on 07/14/2015 07:39 am
https://twitter.com/patriciavmayes/status/620858977602154496
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/14/2015 08:22 am
I'm not sure any existing manufacturer is a particularly good fit - the proposed skin and frame construction seems quite unlike modern aeroplanes.
Welcome to the forum.
TBH you're right, it's more the process of mfg and getting type approval for a large aeronautical project that they need. I think some of the "regional jet" mfg's might have a shot but AFAIK there are so few of them left  :(
Quote
Airliner wings are quite unlike what will be needed for this mach 5 'plane, and I would guess the scale of the wings also leaves fighter jet builders with little relevant experience.
Also true. Most large aircraft use the wings as fuel tanks, absolutely out of the question for LH2.
Quote
While Airbus Group might seem to be the "obvious" choice, they're pretty invested in Arianne, so the politics could be interesting.
Well Airbus has a division working on A6, it's a question of how much autonomy a "Skylon Division" would have and how much the parent could influence it. I'll note some REL staff have experience of both Anglo French and pan European projects from Concorde through (IIRC) Tornado and Typhoon.
Quote
But this seems to be very much cart before the horse. While an awful lot of design work has gone into a craft to fly the SABRE, that work was needed to ensure SABRE was worth developing. Now a working engine is needed before it would be sensible to begin work on the craft.
True. 2016/17 should be very exciting.
We're in danger of talking past each other here. There are at least two points being argued for, which are fairly distinct:

1] If REL is looking for an airframer to build Skylons, Lockheed Martin is not an obviously good choice.
Agreed.
Quote
2] If REL is looking to license some of its recently patented technologies (multiple), then Lockheed Martin is a likely customer as they deal in products that could potentially benefit from them, e.g. military jet/UAV/cruise missiles, etc.
Reasonable.
ok, so we can exclude LM from the picture. Who else should be dropped?

Why are you assuming this technology is only for commercial/civilian purposes because if you are then you're being very, very naive.

I'd put reasonable money on this seeing use in the military long before it has commercial use.
Good luck with that.

Light weight high efficiency heat exchangers have a number of civilian and military applications but none of them get REL closer to their goal of building an RLV.

SABRE's sole function is as a launch system. The notion that hypersonic cruise can become launch  is one actively promoted by the US SCRamjet community, who've probably had $5-10Bn (inflation adjusted) from the late 1950's to demonstrate their plan and took till 2004 to get positive thrust in a flight vehicle (X-43A).

If you want a hypersonic cruise engine you design a hypersonic cruise engine, you don't under run a launch engine.

REL and the USAFRL understand this quite well.

There is also the little problem that M5+ cruise is like continuous re-entry. Skylon's trajectory gains and sheds heat in a way that is impossible for a cruise vehicle to do at anything like constant altitude.

The engine is just the start.  :(

Well if you're the U.S. & want REL's technology for military use then I would think that's precisely what makes LM a strong choice.
There is the small matter of what REL want.

It is after all their technology.  :(

I read that the Altas V was developed for a US Airforce program.
It was.

Both the Atlas V and Delta IV were developed at USAF request under the EELV programme. Both companies committed their own funds (or staff and facilities equivalent to substantial funds) to their efforts and (in theory) one of them would become sole provider to the USG for most USG launches. The other would then have to rely on commercial launches.

IRL the down select never happened, the launch market suffered one of its periodic droughts and they merged into ULA, where they've enjoyed a monopoly of large USG launches ever since.
Quote
   Are they the type of company to start a risky new venture that doesn't have a big guaranteed customer such as the government?  e.g. there are people who say that about BAE.
Indeed.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/14/2015 08:26 am
https://twitter.com/patriciavmayes/status/620858977602154496
Now that injection plate is intriguing.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/14/2015 09:49 am

https://twitter.com/patriciavmayes/status/620858977602154496
Now that injection plate is intriguing.

Why is that?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 07/14/2015 01:52 pm
update from REL website.

looks like production is ramping up

http://www.reactionengines.co.uk/news_14july2015_vacfurnace.html

(edit)

morever, if it works and pre-coolers are in fact requested by the market, they could easily build a second furnace to sell the precoolers to other customers and so finance part of the engine development
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 07/14/2015 02:54 pm
Point taken  - I'm working on some major fixes for the website. It'll be a while yet, but watch this space! (excuse the pun...)

Three cheers for JN for giving us a story we can link to easily (about the furnace).   Yay and thank you. 8) ;D
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alpha_Centauri on 07/14/2015 07:44 pm
Curious comment from the UK space conference;

https://twitter.com/pbdes/status/621009703066279936?s=17

Anyone know what this is about? The only proposal I know of on that scale is REL's Blue Boomerang...

http://sec.kingston.ac.uk/uklaunch/docs/Reaction%20Engines%20Blue%20Boomerang%20-%20Light%20Launcher.pdf
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 07/14/2015 11:05 pm
When doing commercial feasibility studies cubesats currently cost $50,000 - $100,000 per kilogram to launch. This decreasing price includes share of the launch vehicle, deployment hardware, safely inspection and possibly the kick stage. A primary cubesat launching mission can aim for polar orbits or carry medium sized satellites containing propellant.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 07/14/2015 11:15 pm
update from REL website.

looks like production is ramping up

http://www.reactionengines.co.uk/news_14july2015_vacfurnace.html

(edit)

morever, if it works and pre-coolers are in fact requested by the market, they could easily build a second furnace to sell the precoolers to other customers and so finance part of the engine development
Look like RE learnt something publicity.

This is actually what going to make it hard for other people to copy Reaction Engine technology even with the patents in the public, the technology to actually manufacture the pre coolers, some of it was developed perfected by Reaction Engines themselves and I very much doubt we will see those being patented anytime soon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 07/14/2015 11:21 pm
Curious comment from the UK space conference;

https://twitter.com/pbdes/status/621009703066279936?s=17

Anyone know what this is about? The only proposal I know of on that scale is REL's Blue Boomerang...

http://sec.kingston.ac.uk/uklaunch/docs/Reaction%20Engines%20Blue%20Boomerang%20-%20Light%20Launcher.pdf
There been a lot of talk about UK financing indigenous a single stage to orbit rockets for small rockets capable of launching from the UK. There was talk about Virgin Galactic doing something in the UK but from what I hear their efforts confined to America at the minute, through their main customer is a British satellite firm.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/15/2015 06:42 am
This is actually what going to make it hard for other people to copy Reaction Engine technology even with the patents in the public, the technology to actually manufacture the pre coolers, some of it was developed perfected by Reaction Engines themselves and I very much doubt we will see those being patented anytime soon.
Correct.

The patents will tell you if you make an HX with tubes this size and in this layout it will have roughly this capability.

But once you run the numbers for your design you discover that such an HX takes millions of joints that have to be close to perfect first time (it's unlikely rework is possible)

That's to say better than a 1 in 1000 000 failure rate.

How you do that is what REL know. I'm sure they will build stuff using their technology for paying customers, but I'd suggest if they are wise they don't export the technology.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: momerathe on 07/15/2015 04:06 pm
I'm not sure any existing manufacturer is a particularly good fit - the proposed skin and frame construction seems quite unlike modern aeroplanes.

Airliner wings are quite unlike what will be needed for this mach 5 'plane, and I would guess the scale of the wings also leaves fighter jet builders with little relevant experience.

I take your point, but I'm mainly thinking about the depth their pockets. IIRC REL's development cost estimates for Skylon were comparable to the A380..
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Prober on 07/15/2015 04:07 pm
some 3D printer tech for Skylon

http://forum.nasaspaceflight.com/index.php?topic=33141.msg1404984#msg1404984

now I need to backtrack and read all your posts :-X
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/16/2015 01:12 am
I agree they're an unlikely partner, however the SR-71 gives them some relevant experience - the skin, and supporting engines on low thickness wings.
That was about 55 years ago. The Ford Trimotor also used a corrugated skin design.

LM seems to be pursuing (or rather pursuing funding for) their "SR72" concept with an Aerojet provided Dual Mode Scramjet.

There are 2 problems with LM.
1) is they are American and Skylon needs to sell on an international basis to make profit and this will get very bogged down in US ITAR rules despite it being designed to look and operate as little like an ICBM as possible
2) They are Lockheed Martin. Looking over their 110+ page corporate accounts tells you their basic business model is "Sell stuff and services to the US Government." ULA is 10% of their profit and I doubt more than  20% of that is from someone that isn't a part of the USG or some other government. 

That might be useful when it comes to selling it to other governments but it does not suggest they are good at managing a commercially funded project on time and budget when their usual MO is call up the DoD/NRO/NASA for more money especially when there is an in house programme already in place through ULA.   :(

There is a reason that when NASA ran the NAFCOM cost model for the Commercial Cargo programme over SX they thought it would cost roughly 9x what SX spend on F1 and F9.

It's the cost over runs on US government aerospace projects going back decades gradually shifting the "centre of mass" of costs upward.  :(


Quote
If nothing else, a revenue stream would get them closer to their goal. I'm sure there is a large element of investor palatability, but Reaction Engines as a company was set up to sell heat exchangers. See also their wholly owned subsidiary "Skylon Enterprise Ltd"
True, a steady non research revenue stream of decent size would  help a lot in moving the project along.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/16/2015 07:58 pm
Quote from: http://www.reactionengines.co.uk/lapcat.html
The A2 airframe also has technology commonality with the SKYLON launch vehicle. [...] it is anticipated that the A2 airframe would be constructed as a similar multi-layer structure to SKYLON [...]
once a company was building *that* sort of aeroplane, slipping a Skylon into the mix would be a lot easier.
That's a bit of a chicken & egg problem

A2 is a very long way from being built.
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/20/2015 05:15 pm
This seems appropriate here.

Mach 5 Airliner Operations Face Huge Challenges

Quote
Will hypersonic airliners be too hot to handle . . . literally? The issues involved in ground handling of a Mach 5-plus transport still simmering after its intercontinental hypersonic hop are among the unique challenges being considered as researchers address the potential operation of future high-speed airliners. While most hypersonic transport projects have focused on the basic design and aerodynamic, propulsion, structures and systems technologies required, the operational aspects are ...

http://m.aviationweek.com/commercial-aviation/mach-5-airliner-operations-face-huge-challenges
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Glom on 07/20/2015 07:16 pm
Maybe an early deceleration to allow for cooling in the terminal phase?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: tl6973 on 07/21/2015 02:31 pm
Hello all,

Long-time lurker, first time poster.

I would imagine that it is probably easier to build Skylon before getting into anything like the A2, for a number of reasons:

1. Skylon is designed for a lifetime of 200 flights, spending only minutes each in hot "hypersonic cruise" (ie re-entry) conditions. this also goes for airframe loading cycles. This is compared to the requirement of at least thousands of hours (if not tens of thousands) and cycles for a civil airliner. therefore one would expect the sklyon airframe design to be a better first one to try.

2. There is a proven, existing market for Skylon - in fact, Skylon has been designed specifically based on the GEO comsat market. whereas, Lapcat is really a feasibility study, without the robust business case required to support investment/ development.

3. The amount of new cryogenic fuel supply infrastructure required for Skylon is far less than for something like an A2 - Skylon only needs it at enough launch sites to get to the right orbits, whereas a useful passenger plane will need supply at every place that people actually want to go.

As for the temperature of a just-landed A2, I imagine in normal aircraft operations you would have at least half an hour of subsonic flight before landing during which to cool down (getting in the runway queue for one thing), plus any active cooling if run at subsonic would bring the temperature down pretty fast, plus a low heat-capacity skin material, so i wonder if this might be a bit of a non-problem. Can anyone tell me if there were/ are heat handling issues with the Shuttle/ X37B post-landing?

I hope these are valid points and am very happy to be corrected on them, just pleased to be part of the discussion :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/21/2015 09:01 pm
Hello all,

Long-time lurker, first time poster.
Welcome. 
Quote
I would imagine that it is probably easier to build Skylon before getting into anything like the A2, for a number of reasons:

1. Skylon is designed for a lifetime of 200 flights, spending only minutes each in hot "hypersonic cruise" (ie re-entry) conditions. this also goes for airframe loading cycles. This is compared to the requirement of at least thousands of hours (if not tens of thousands) and cycles for a civil airliner. therefore one would expect the sklyon airframe design to be a better first one to try.
This may be the difference between launch and cruise. The short length of time offers options that simply can't last the length of a long trip.
Quote
2. There is a proven, existing market for Skylon - in fact, Skylon has been designed specifically based on the GEO comsat market. whereas, Lapcat is really a feasibility study, without the robust business case required to support investment/ development.
That's a mistake on my part. Hempsell stated that REL looked at various uses for the vehicle in terms of velocity requirements. The delta V needed for comm sats turned out to be the sizing limit, but comm sat delivery is a key part of the economic case.

You're right about LAPCAT. In fact its the the engine. A2 was the aircraft design,but it was always more of an outline of the vehicle you'd need to carry it.
Quote
3. The amount of new cryogenic fuel supply infrastructure required for Skylon is far less than for something like an A2 - Skylon only needs it at enough launch sites to get to the right orbits, whereas a useful passenger plane will need supply at every place that people actually want to go.
True.  The cost of the fuel infrastructure was a major reason for cancelling the SR71 and LH2 is much tougher to handle.
Quote
As for the temperature of a just-landed A2, I imagine in normal aircraft operations you would have at least half an hour of subsonic flight before landing during which to cool down (getting in the runway queue for one thing), plus any active cooling if run at subsonic would bring the temperature down pretty fast, plus a low heat-capacity skin material, so i wonder if this might be a bit of a non-problem. Can anyone tell me if there were/ are heat handling issues with the Shuttle/ X37B post-landing?
The Shuttle had issues in this area. I recall something about the door area being at its hottest after landing. OTOH Shuttle covering was a mix of ceramic blankets and open cell ceramic foam. It's easy to see how these could be strongly heated during re entry and then form a layer of stagnant air around the vehicle during landing, making heat release quite a slow process.

But Skylons skin is a series of thin plates, which won't trap stagnant air. I'm not sure if it qualifies as "low" heat capacity.

I'd be very surprised if REL didn't get access to the NASA TPSX database on TPS materials for the Shuttle. I'd guess they've run quite a few simulations on Skylon entry by now  and have a pretty good idea of the vehicles temperature profile as it takes off and lands.
Quote
I hope these are valid points and am very happy to be corrected on them, just pleased to be part of the discussion :)
You're points are very valid.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 07/21/2015 11:50 pm
Is it not possible, even likely, that Lapcat/A2 was simply the wrong requirement? Yes ESA had good reasons for creating a future aircraft study and REL did a fine job of meeting their study needs, but that doesn't mean it's the best idea.

Once SABREs are shown to be effective and robust (here's hoping!) the entire focus of long-distance high speed air travel may well switch to sub-orbital hopping in a passenger vehicle with SABRE like engines. Why spend 5 hours getting from Europe to Australia (very impressive) when you can do it in 45 minutes - AND avoid all those really very difficult to solve skin heating issues.

Currently, people just don't think of a safe 'space' plane with high passenger numbers as a realistic option because it "isn't possible".
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: QuantumG on 07/22/2015 12:01 am
It's hard to see how flying through the atmosphere for longer, in an SSTO, is going to make a space plane safer.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RobLynn on 07/22/2015 02:30 am
Is it not possible, even likely, that Lapcat/A2 was simply the wrong requirement? Yes ESA had good reasons for creating a future aircraft study and REL did a fine job of meeting their study needs, but that doesn't mean it's the best idea.

I don't think M5 is really needed or a good idea.  Why not make it way easier on yourself and just go Mach 3 - then you can use simple titanium structure and skins, cheap turbo ramjets without high risk heat exchangers, bascially little new tech requried, also an L/D of 7-8 (probably 15-30% lower fuel burn than L/D~6 Lapcat), and still get antipodial range in 6 hours.  For total trip time of probably 11-12 hours door to door vs 9-10 hours for Mach5 and 30 hours for conventional subsonic.

At the end of the day seat-mile cost for such an aircraft is likely to be half the estimated $4-5k antipodal ticket cost of Lapcat.  And demand curves being what they are that probably increases your market by an order of magnitude and the potential commercial viability from no-chance, to maybe.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 07/22/2015 02:37 am
It's hard to see how flying through the atmosphere for longer, in an SSTO, is going to make a space plane safer.

I am not a space expert. What I meant was flying a Skylon-like trajectory to get you to your destination - I meant absolutely not staying in the atmosphere and therefore avoiding those heating issues. Clearly re-entry has to be considered too, but that would already be worked through to some extent should Skylon-like craft actually get built.

I also wasn't implying any of that made it safer, but there is no reason why at some future date such a thing couldn't be relatively safe.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/22/2015 06:59 am
Is it not possible, even likely, that Lapcat/A2 was simply the wrong requirement? Yes ESA had good reasons for creating a future aircraft study and REL did a fine job of meeting their study needs, but that doesn't mean it's the best idea.
ESA didn't issue this requirement.

LAPCAT was a research project from the EU under one of their FRAMEWORK R&D schemes, which encourage pan European co operation to solve common problems to a pre competitve stage. You might think of them as being like the sort of thing that the US DARPA and E-DARPA do, but including Canada and Mexico. FRAMEWORK programmes have supported everything from next generation chip lithography to domestic heat and power concepts using natural gas fuel cells. :)
Quote
Once SABREs are shown to be effective and robust (here's hoping!) the entire focus of long-distance high speed air travel may well switch to sub-orbital hopping in a passenger vehicle with SABRE like engines. Why spend 5 hours getting from Europe to Australia (very impressive) when you can do it in 45 minutes - AND avoid all those really very difficult to solve skin heating issues.
It's an interesting idea but misses a few factors. Hempsell said a sub orbital Skylon flight could carry 30 tonnes, but passenger wise I think the payload bay is volume limited, not mass limited.

What Concorde demonstrated (and what the Boeing SST got right) was you need to carry a lot of passengers (in substantial comfort) to make it worthwhile. Most (all) post flight analysis of Concorde's economics said it was too small, and should have been 2x or 3x bigger (and the French wanted it smaller  :( )
Quote
Currently, people just don't think of a safe 'space' plane with high passenger numbers as a realistic option because it "isn't possible".
REL are quit clear that LAPCAT/A2 is not a space plane but a very fast conventional airliner, designed to carry large number of passengers (not "spaceflight participants") with minimal special training and incorporating things like powered landings. Like getting on any large general aviation aircraft, but for less time.

It's pretty clear if a > M2.2 transport gets built it will be a very different beast from Concorde, due to thermal considerations alone. It's also likely to different from Skylon.

I don't think M5 is really needed or a good idea.  Why not make it way easier on yourself and just go Mach 3 - then you can use simple titanium structure and skins, cheap turbo ramjets without high risk heat exchangers, bascially little new tech requried, also an L/D of 7-8 (probably 15-30% lower fuel burn than L/D~6 Lapcat), and still get antipodial range in 6 hours.  For total trip time of probably 11-12 hours door to door vs 9-10 hours for Mach5 and 30 hours for conventional subsonic.
Perhaps you should ask the EU that question.

They set the requirements.
Quote
At the end of the day seat-mile cost for such an aircraft is likely to be half the estimated $4-5k antipodal ticket cost of Lapcat. 
Based on what exactly?
Quote
And demand curves being what they are that probably increases your market by an order of magnitude and the potential commercial viability from no-chance, to maybe.
I've flown on those $5k business class tickets.

They did not seem to have any trouble filling seats, or rather individual "pods"

At a certain level of business the key constraint is no  longer money it's time, and M5 means you spend less of it in the air.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 07/22/2015 08:04 am
there is another problem with a suborbital skylon- the pricing would be totally out of reach for everyone but the wealthiest. A LEO Skylon launch, in the best scenario possible, could lower the kg/price down to 350$. Even assuming lower costs for suborbital flights (let's say 150$ kg) and assuming it could carry 60 people (the double of a LEO flight) it would still be almost 40k $ per ticket. not much compared to the 200.000$/ticket it would cost to bring one passenger to LEO in the best-case scenario, but still....
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/22/2015 12:11 pm
there is another problem with a suborbital skylon- the pricing would be totally out of reach for everyone but the wealthiest. A LEO Skylon launch, in the best scenario possible, could lower the kg/price down to 350$. Even assuming lower costs for suborbital flights (let's say 150$ kg) and assuming it could carry 60 people (the double of a LEO flight) it would still be almost 40k $ per ticket. not much compared to the 200.000$/ticket it would cost to bring one passenger to LEO in the best-case scenario, but still....
Exactly.

Using a Skylon for occasional point to point delivery of high value goods may be viable as part of an operators business case (probably not an early adopter, but in a later wave of buyers) but it's not what Skylon is designed to do.

Such a transporter, flying either a sub orbital or a cruise trajectory, would need to be a very different vehicle. The upside is the maximum powered velocity would be lower (shrinking the vehicle) it would be all air breathing (eliminating the LOX tanks, also shrinking the vehicle), but then you need to make the payload bay much bigger. An early REL estimate was the Skylon design could carry 30 passengers but that was scaled down to split them into "short stay" IE coming back on the same Skylon that took them to (notionally) the ISS and "long stays" who'd been on orbit for months (years) and would need to come down on basically a stretcher.

Now sub orbital is a short flight (a LEO orbit is 90 mins, 45 min puts you anywhere on the planet from your launch point) so consumables should be minimal but the fact remains even if you increase the seating density (45 in the bay?) that's just not going to cut it when you're looking at needing 250-300  :(

Wheather it's a M5 cruising aircraft or a sub orbital vehicle (I don't think there's even an agreed term for one of these. SOV?) it won't be a Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: tl6973 on 07/23/2015 12:00 pm
I find it hard to pin down what I find most exciting about REL.

It's a toss-up between the engineering wonderments of SABRE and Skylon, and the actual Business Culture/ operating model of REL themselves.

There's plenty on this thread about the science, engineering and economics, so I'd like to talk more about the business. They seem to occupy this very intriguing, contradictory spot between old and new space - like a start up but with 30 years' experience/ existence, with a visionary idea but that will clearly require significant collaboration with traditional aerospace and government/ political bodies. A bunch of very British Boffins in a shed, with the increasing possibility of changing the entire game.

Of course it is very hard to comment accurately on an organisation from outside, but I am very impressed with their calm determination, ability to stay completely focused on a very clearly defined technology development roadmap, and organisational unity/ rationality/ lack of internal politics and strife.

I would be very interested to know people's thoughts on how this has come about. Is it down to strong visionary leadership? is it that having a small team and constrained resources forces one to maintain focus? is it simply because the design concept is so compelling? Was the experience of working with the government on HOTOL a good lesson in how NOT to run a development programme? or is it something else entirely?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 07/23/2015 02:04 pm
It's an interesting idea but misses a few factors. Hempsell said a sub orbital Skylon flight could carry 30 tonnes, but passenger wise I think the payload bay is volume limited, not mass limited.

I accept everyone's points (although as usual perhaps not QuantumG's  ;) ), but I was trying to imagine a different study or future. One where a craft was specifically optimised for maximum passenger carrying purposes and sub-orbital - whatever the trajectory would be to minimise time in atmosphere, but maximise distance. So yes, not Skylon. A2 isn't Skylon either.

I am not at all saying that LAPCAT wasn't a useful study, I am merely suggesting that if the EU had given REL the money for a different study, to look into *that* sort of vehicle, they might have been able to propose a realistic design, different from both A2 and Skylon, but still using technology derived from SABRE engine technology, that would seat a significant number of passengers to make an economically viable vehicle and avoid the in-atmosphere heat problems.

Then we might get our 45 minute trip - and one hell of a ride ;)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RonM on 07/23/2015 02:24 pm
It's an interesting idea but misses a few factors. Hempsell said a sub orbital Skylon flight could carry 30 tonnes, but passenger wise I think the payload bay is volume limited, not mass limited.

I accept everyone's points (although as usual perhaps not QuantumG's  ;) ), but I was trying to imagine a different study or future. One where a craft was specifically optimised for maximum passenger carrying purposes and sub-orbital - whatever the trajectory would be to minimise time in atmosphere, but maximise distance. So yes, not Skylon. A2 isn't Skylon either.

I am not at all saying that LAPCAT wasn't a useful study, I am merely suggesting that if the EU had given REL the money for a different study, to look into *that* sort of vehicle, they might have been able to propose a realistic design, different from both A2 and Skylon, but still using technology derived from SABRE engine technology, that would seat a significant number of passengers to make an economically viable vehicle and avoid the in-atmosphere heat problems.

Then we might get our 45 minute trip - and one hell of a ride ;)

That would be fun, but I don't see it happening. There are no operational SSTs today because of cost, so I doubt suborbitals would be economically viable. Even the military doesn't have supersonic transports, let alone suborbitals.

Teleconferencing takes care of rapidly attending business meetings and missiles takes care of rapidly needing to reach out and touch someone.

An issue with suborbital passenger transport is all the time on the ground. You go to the airport, wait in the security line, wait to board, wait for takeoff, ***high speed flight***, wait to land, wait to disembark, wait for your luggage, wait in line for customs, leave airport and arrive at hotel. I'd rather take a cheaper subsonic flight and take a nap while in the air.

Skylon could make an interesting SSTO spacecraft, but I doubt it or any other technology will succeed as a suborbital transport.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 07/23/2015 02:37 pm
That would be fun, but I don't see it happening.

Ah! "There's no market for it"  :)

Even if that's true, it would be an interesting study.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 07/24/2015 07:23 am
An issue with suborbital passenger transport is all the time on the ground. You go to the airport, wait in the security line, wait to board, wait for takeoff, ***high speed flight***, wait to land, wait to disembark, wait for your luggage, wait in line for customs, leave airport and arrive at hotel. I'd rather take a cheaper subsonic flight and take a nap while in the air.

Skylon could make an interesting SSTO spacecraft, but I doubt it or any other technology will succeed as a suborbital transport.

To solve a problem you first have to "have it".  We haven't really fixed the issues of the time it takes to offload and process people because perhaps we are only just beginning to experience them.

I still wonder if a ticket that cost you e.g. 5000 wouldn't also pay for expedited customs processing - or even perhaps processing onboard the flight.

As for getting on and off - I'm not saying this is the answer but at least people are thinking about the problem:

http://clipair.epfl.ch/
[youtube]
NEJ3bAh7LUw[/youtube]

I love it because I had a similar idea not long ago and it's nice to know it wasn't so ridiculous as to not even be considered. :-)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 07/24/2015 10:09 am
50k more likely than 5k.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/24/2015 10:32 am
To solve a problem you first have to "have it".  We haven't really fixed the issues of the time it takes to offload and process people because perhaps we are only just beginning to experience them.

I still wonder if a ticket that cost you e.g. 5000 wouldn't also pay for expedited customs processing - or even perhaps processing onboard the flight.

As for getting on and off - I'm not saying this is the answer but at least people are thinking about the problem:
I had a similar idea not long ago and it's nice to know it wasn't so ridiculous as to not even be considered. :-)
I understand that the trip through Reagan at Washington DC is very fast.

It can be done if law makers are feeling inconvenienced enough to do something about it.  :(

Likewise a service that preloaded all your address, hotel and credit card details on a data base that is used to upload to the DHS system to expedite trips to and from the US was offered some years ago.

Until someone stole the laptop on which a copy was sitting from a locked office in the secure area of a major airport (as happened a few years ago).

As for this cargo module idea, considered and built (in the 1940's or 50's) in prototype by (IIRC) the Fairchild aircraft company.

The problem has always been compatibility.  You end with using the lowest common denominator.

Which turns out to be a) A person walking or b) A standardized air cargo package.

[EDIT and here it is.

https://en.wikipedia.org/wiki/Fairchild_XC-120_Packplane ]
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 07/27/2015 09:32 am
Reaction Engines concept  of a full-scale Sabre ground demonstrator.
Clearly not a flight model engine yet, but massive progress if this proves successful in 2018/2019.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/27/2015 10:43 am
Reaction Engines concept  of a full-scale Sabre ground demonstrator.
Clearly not a flight model engine yet, but massive progress if this proves successful in 2018/2019.
Where did this come from?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 07/27/2015 11:17 am
From the Aviation Week digital magazine. Photo credit  Reaction Engines
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: aga on 07/27/2015 12:07 pm
from here, i guess (?):
http://aviationweek.com/technology/air-breathing-sabre-concept-gains-credibility
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 07/27/2015 01:50 pm
So many things wrong with that picture....
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/27/2015 03:19 pm
So many things wrong with that picture....
I'd certainly say it look like it was made by a graphics artist, not an engineer.

What specifically did you have in mind?
Title: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 07/27/2015 04:39 pm
Oh, it shows the engine running at power but just placed in some kind of better workshop table assembly. So it doesn't have any thrust?
Four radiation cooled nozzles that close to each other would immediately burn through.
With all that it's almost irrelevant that all the deep-cold cryo piping is uninsulated and that the air inlet would suck up all kind of stuff at that power and so on.

It's so: oh, we have this image of the raw engine assy, let's just display it at work....
And then let's add these glowing red-hot engine bells people know from the SpaceX videos, they look so cool...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 07/27/2015 05:15 pm
It has come from  Aviation Week, who are crediting it to Reaction Engines, if this is correct,we have to ask what
is the purpose of what you guys clearly feel does not have any real engineering relevance to a fully engineered prototype engine on its test stand.



Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 07/27/2015 05:23 pm
Why all the consternation? It's just a notional graphical representation of a current project from a company that is not known for spending a lot of effort on PR materials. As far as I can tell the glass is half full.

And it's not as if other companies (i.e. SpaceX) haven't released graphics and animations before now that are notional at best.
___________
Plus the SABRE 4 cycle is still under wraps, so that's an additional good reason to show something vaguely representative rather than rendering the actual test bed design.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 07/27/2015 05:38 pm
In the past Reaction Engines have always produced nothing less than full on engineering diagrams.

Possibly they are now starting to use PR in a much more positive way.

The new MD no doubt will want to raise the profile of the company as they push for more funding, which over the next few years will need to be not millions but billions!
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 07/28/2015 05:30 pm
For those of us that aren't subscribed to Aviation Weekly, does it say anything new or interesting in the article?  Thanks.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 07/28/2015 08:05 pm
For those of us that aren't subscribed to Aviation Weekly, does it say anything new or interesting in the article?  Thanks.

Hi Citizen Wolf,

If you view aga's post it has a link to the Aviation Week's article.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ElGuapoGuano1 on 07/28/2015 08:15 pm
Hankelow8, right, but as was said, if you are not subscribed to Aviation Week, you don't really see the article, you only get a paragraph...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 07/28/2015 08:23 pm
@Hankelow8
If you're not subscribed to Aviation Weekly you come up against a pay wall and can't see the article.

EDIT: oops sorry, ElGuapoGuano has already said the same thing.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: kch on 07/28/2015 08:42 pm
Hankelow8, right, but as was said, if you are not subscribed to Aviation Week, you don't really see the article, you only get a paragraph...

... not worth clicking, really (unless you're a subscriber).  "Next!"
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/29/2015 03:41 pm
From the Aviation Week digital magazine. Photo credit  Reaction Engines
That's an interesting qualification.

I've just seen the hard copy version (dated July 20th onward) and this picture is not in there .

The article is a one pager and seems to part of their coverage of the AIAA Hypersonics and reentry conference, held (for reasons I'm not clear about) in Glasgow, Scotland.

It's only illustration is a cutaway of the pre cooler/front of engine section of SABRE.

There are also reports on hypersonic airliner design where efforts are being made to combine European and Japanese efforts in this area LAPCAT is mentioned but initial goals are for a 100 seat design at a price  2x that of current average business class tickets. They are targeting 200 such vehicles globally with point to point services for routes over up to (and ideally around ) 6200nm.

Possibly the most relevant item to Skylon were the data points from SR71 operations. The M5 airliner concept is targeting 48 hr turnaround. Comments by former SR71 staff state that when flying it took 19 hrs to go from a flight request to takeoff for a flight ready aircraft (IE not needing overhaul).

They noted that to get it ready for a next flight would take (on average) 1 week and if serious work needed to be done then about 1 month. They listed several areas of problems but the only one I recall was rivets being popped by the flight conditions.

I suspect at least one member of REL was at the conference and was taking careful notes of such points, if they weren't already aware of them, to refine their Skylon plans.

I also found the "commentary" section on page 11, on why grouping "Aerospace" with "Defense" is becoming increasingly misleading. It compared Airbus, Boeing and LM product mixes.

I'm not the only one who thinks of LM as strictly a government contractor and nothing else.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 07/29/2015 03:45 pm

I'm not the only one who thinks of LM as strictly a government contractor and nothing else.

Doesn't mean it is right.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/29/2015 10:05 pm

I'm not the only one who thinks of LM as strictly a government contractor and nothing else.

Doesn't mean it is right.
When it's someone who makes their living analyzing companies in (or not in) the aerospace and defense business whose reputation matters to them I think that adds credibility to the view.

However let's look at LM's market segments, from their 2014 annual report.

Aeronautics.
"is engaged in the research, design, development, manufacture, integration, sustainment, support and upgrade of advanced military aircraft,"
IE Military aircraft, mostly for the US government.

Information Systems & Global Solutions.
"IS&GS provides advanced technology systems and expertise, integrated information technology solutions and management services across a broad spectrum of applications for civil, defense, intelligence and other government customers. "
So basically selling IT systems and services to governments.

Missiles & Fire Control.
I think this is pretty self explanatory. Not something you sell to private customers.

Mission Systems & Training
"In 2014, U.S. Government customers accounted for 75%, international customers accounted for 24% and U.S. commercial and other customers accounted for 1% of MST’s net sales."
So 1% of this segments $7.1Bn revenue is from civilian customers.

Space Systems
"In 2014, U.S. Government customers accounted for 97%, international customers accounted for 1% and U.S.commercial and other customers accounted for 2% of Space Systems’ net sales. "
So maybe 2% of their $8.1Bn revenue is commercial.
"Operating profit for our Space Systems business segment includes our share of earnings for our 50% ownership interest in United Launch Alliance (ULA)."

On that basis I think I'd suggest most people looking at LM would conclude it's essentially a government contractor, mostly (but not entirely) for the US government. Non governmental works is a very small part of their total revenue.

Which I would suggest makes them about the worst candidate for building a large commercially funded project to a (relatively) tight time scale and budget, where you can't get an additional appropriation if you overrun your budget.
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/29/2015 11:15 pm

I'm not the only one who thinks of LM as strictly a government contractor and nothing else.

Doesn't mean it is right.
When it's someone who makes their living analyzing companies in (or not in) the aerospace and defense business whose reputation matters to them I think that adds credibility to the view.

However let's look at LM's market segments, from their 2014 annual report.

Aeronautics.
"is engaged in the research, design, development, manufacture, integration, sustainment, support and upgrade of advanced military aircraft,"
IE Military aircraft, mostly for the US government.

Information Systems & Global Solutions.
"IS&GS provides advanced technology systems and expertise, integrated information technology solutions and management services across a broad spectrum of applications for civil, defense, intelligence and other government customers. "
So basically selling IT systems and services to governments.

Missiles & Fire Control.
I think this is pretty self explanatory. Not something you sell to private customers.

Mission Systems & Training
"In 2014, U.S. Government customers accounted for 75%, international customers accounted for 24% and U.S. commercial and other customers accounted for 1% of MST’s net sales."
So 1% of this segments $7.1Bn revenue is from civilian customers.

Space Systems
"In 2014, U.S. Government customers accounted for 97%, international customers accounted for 1% and U.S.commercial and other customers accounted for 2% of Space Systems’ net sales. "
So maybe 2% of their $8.1Bn revenue is commercial.
"Operating profit for our Space Systems business segment includes our share of earnings for our 50% ownership interest in United Launch Alliance (ULA)."

On that basis I think I'd suggest most people looking at LM would conclude it's essentially a government contractor, mostly (but not entirely) for the US government. Non governmental works is a very small part of their total revenue.

Which I would suggest makes them about the worst candidate for building a large commercially funded project to a (relatively) tight time scale and budget, where you can't get an additional appropriation if you overrun your budget.

Military government applications are likely to reach reality before any commercial ones are and in that case LM are ideally placed.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/30/2015 07:06 am
Military government applications are likely to reach reality before any commercial ones are and in that case LM are ideally placed.
That's an assertion.

Perhaps you could take us through your reasoning?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 07/30/2015 07:18 am
guys, did you see the design for an airbreathing nuclear rocket reported by nextbigfuture? I know that it's just summer speculation, but I was wondering whether an integrated design with the SABRE is, as a pure matter of principle, possible.

http://nextbigfuture.com/2015/07/nuclear-thermal-turbo-rocket-with.html
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 07/30/2015 10:46 am
The Aviationweek article is now generally available.  I suppose the idea is that subscribers get it early but the public gets it eventually.

Here's the link again:
http://aviationweek.com/technology/air-breathing-sabre-concept-gains-credibility?NL=AW-05&Issue=AW-05_20150730_AW-05_233&sfvc4enews=42&cl=article_1&utm_rid=CPEN1000001204273&utm_campaign=3312&utm_medium=email&elq2=de275daceef84b74b5541bcb84290e12
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/30/2015 12:08 pm
Military government applications are likely to reach reality before any commercial ones are and in that case LM are ideally placed.
That's an assertion.

Perhaps you could take us through your reasoning?

Fairly simple the military will always get first dibs on something like this once they are persuaded it works and does what it says on the can. The commercial sector is often more risk adverse and though the military can be conservative in these things as well, if they are persuaded they are far more likely to put money into something like this.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: oddbodd on 07/30/2015 01:06 pm
guys, did you see the design for an airbreathing nuclear rocket reported by nextbigfuture? I know that it's just summer speculation, but I was wondering whether an integrated design with the SABRE is, as a pure matter of principle, possible.

http://nextbigfuture.com/2015/07/nuclear-thermal-turbo-rocket-with.html

Fission is a barely controlled potential runaway catastrophe. And the idea of strapping one to a type of vehicle that flies over our heads, and typically has a 1 in 50 chance of exploding... I would never say never, but very unlikely. The US and USSR experimented with nuclear powered airplanes, but they only did a few test flights with the reactor on board, and not active, before the ICBM made them pointless. One of the issues was the mass for shielding, and in a mass sensitive concept like Skylon, it just doesn't make sense as far as I can see.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 07/30/2015 01:22 pm
On that basis I think I'd suggest most people looking at LM would conclude it's essentially a government contractor, mostly (but not entirely) for the US government. Non governmental works is a very small part of their total revenue.

Which I would suggest makes them about the worst candidate for building a large commercially funded project to a (relatively) tight time scale and budget, where you can't get an additional appropriation if you overrun your budget.

That is a statement based on bias and not supported by any relevant data.  Not all gov't contracts are cost plus.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/30/2015 02:13 pm

On that basis I think I'd suggest most people looking at LM would conclude it's essentially a government contractor, mostly (but not entirely) for the US government. Non governmental works is a very small part of their total revenue.

Which I would suggest makes them about the worst candidate for building a large commercially funded project to a (relatively) tight time scale and budget, where you can't get an additional appropriation if you overrun your budget.

That is a statement based on bias and not supported by any relevant data.  Not all gov't contracts are cost plus.

There seems to be a degree of either accidental or deliberate misunderstanding of LM's business.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 07/30/2015 03:15 pm
guys, did you see the design for an airbreathing nuclear rocket reported by nextbigfuture? I know that it's just summer speculation, but I was wondering whether an integrated design with the SABRE is, as a pure matter of principle, possible.

http://nextbigfuture.com/2015/07/nuclear-thermal-turbo-rocket-with.html

Fission is a barely controlled potential runaway catastrophe. And the idea of strapping one to a type of vehicle that flies over our heads, and typically has a 1 in 50 chance of exploding... I would never say never, but very unlikely. The US and USSR experimented with nuclear powered airplanes, but they only did a few test flights with the reactor on board, and not active, before the ICBM made them pointless. One of the issues was the mass for shielding, and in a mass sensitive concept like Skylon, it just doesn't make sense as far as I can see.

This has actually been extensively discussed in some of the nuclear threads, Ranulf has a lot to say about it. Essentially  the  SABRE cycle is well suited to having a nuclear derivative as the rocket combustion chamber can just be replaced with the reactor and the compressed air can be injected into the nozzle in an air augmented mode, potentially followed by an Lox augmented mode. The technology was actually listed in the 2012 NASA draft technology roadmap.
The performance benefit however is very dependant on how much shielding you require and the T/W of your reactor core. ANP shielding encased the reactor in concentric spheres of tungsten and lithium hydride such that you could stand next to the thing and get more radiation coming in through the window and the plane could plow into a mountain and the shielding would never crack and the reactor never melt down. By the nature of reactor power to mass to volume this meant that ANP only makes performance sense for aircraft sized 500mt and up (A380 sized). So a full ANP shielded SABRE engine would only make sense on a large launch vehicle but just how large depends on your shielding requirements and your reactor T/W.   

 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/30/2015 04:26 pm
guys, did you see the design for an airbreathing nuclear rocket reported by nextbigfuture? I know that it's just summer speculation, but I was wondering whether an integrated design with the SABRE is, as a pure matter of principle, possible.

http://nextbigfuture.com/2015/07/nuclear-thermal-turbo-rocket-with.html
You need to develop a bit more of a feel for engineering.  :(

This thing starts with an unflown concept and stacks the untested ideas on top of it.  Variable pitch fan blade trailing edges structured as linear aerospikes ducting 2000c GH2 through them ::) Most metals melt below this temperature. 

At the end of it you've got something with maybe an Isp of 900sec + and double thrust for a period.

SABRE delivers somewhere around 2-4000 secs without a nuclear fuel element in site.

The Aviationweek article is now generally available.  I suppose the idea is that subscribers get it early but the public gets it eventually.

Here's the link again:
http://aviationweek.com/technology/air-breathing-sabre-concept-gains-credibility?NL=AW-05&Issue=AW-05_20150730_AW-05_233&sfvc4enews=42&cl=article_1&utm_rid=CPEN1000001204273&utm_campaign=3312&utm_medium=email&elq2=de275daceef84b74b5541bcb84290e12

Tried to log in but failed to do so.

Then I read the level of the comments left.

Deeply disappointing.   :(

That is a statement based on bias and not supported by any relevant data.  Not all gov't contracts are cost plus.
I think the LM annual accounts is very relevant data if you're trying to decide how much of a companies revenue comes from being a government contractor or from selling in the open market.

And I have so far said nothing about what proportion of LM's contracts are cost plus or firm fixed price.

I fully accept that something like the Orion capsule will be cost plus (I don't know about you but I'm so excited for when that SM comes in from Europe and it's mated to the capsule for the first time. I'm sure it'll be worth the wait)

OTOH I doubt the F35 production contract is cost plus, give that should have all been worked out in development (although judging by that shoot out with an F16 described in this edition the flight control system seems a bit of tweaking).

Fairly simple the military will always get first dibs on something like this once they are persuaded it works and does what it says on the can.
Unfortunately it doesn't work that way. They may like the technology but the USAF cannot develop it. It has to have a "competition" or very good reasons to have a single source to get a programme going and of course that would leave the USAF with an engine but no aircraft.

Since REL don't make aircraft, that's the job of the Skylon mfg consortium, that leaves them in something of an impasse.
Quote
The commercial sector is often more risk adverse and though the military can be conservative in these things as well, if they are persuaded they are far more likely to put money into something like this.
That's a very sweeping generalization. Strictly speaking it will be the US Congress who puts US taxpayers money into it.

At present I think the USAFRL study provides a strong case to US readers that the technology works.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 07/30/2015 04:58 pm
I have an unpaid login - perhaps that's why I could read it.  It wasn't available to me until today though - perhaps there is some progression.

The interesting bits to me were sort of casting doubt on Skylon being the first application of Sabre.

I'm not sure about copyright so I'm quoting the quotes as I doubt they can be owned:

Quote
"The question to answer next is what benefit the Sabre could bring to high-speed aerospace vehicles compared to other propulsion systems,”

“AFRL is analyzing vehicle designs based on the Sabre engine concept. We are also considering testing their heat-exchanger technology at Mach 5 flight conditions in a high-temperature wind tunnel.”
(Hellman, AFRL)

Skylon is:
Quote
“very risky as a first application,”
“Sabre may provide some unique advantages in more manageable two-stage-to-orbit configurations.”
(Hellman, AFRL)

Quote
“From our perspective there is no cheap, quick way around the problem of space access. We’ve done studies and we agree that [a] sensible second-stage approach might be best to demonstrate the technology by taking it one step at a time,”
(Sam Hutchison, Reaction Engines)

Quote
“Enough people now say the Sabre cycle works and it looks compelling. Now the question is what will we do with it?“ As an engine class, it straddles both air and space, so we have to optimize a system to take advantage of that for a given application. As we structure the development plan going forward, we can figure out what the first use is going to be. So over the next six months we will be closing in on that application.”

“Right now we are in the process of scoping that demonstration engine in terms of what it needs to achieve,”

“The key thing is to tick the boxes in every area it needs to tick. It is all about making sure the demonstrator meets the performance requirements that are set for it. We want to make sure it really works and offers the sort of performance that we say it can do. We’re still in that phase. The studies are in their infancy for the engine demonstrator but we have got to make sure we’re not biting off too much more than we can chew.”

(Hutchison)

Apparently the demonstrator is on track to do a full engine test in  2018/2019.

Ground testing is possible :
Quote
“because the engine uses the atmosphere as the source of its energy and the reaction mass. And because of the clever heat-exchanger technology, we can modulate the air so the turbomachinery in the engine doesn’t know it is on the ground.”
(Hutchison) 

They plan to simulate higher velocity air by raising the temperature of the air entering the inlet. They are also going to do wind tunnel tests with the inlet.

The AFRL suggest that they might do Mach 5 tests in a high temperature wind tunnel.

There are apparently no short term funding shortfalls.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Moe Grills on 07/30/2015 05:04 pm
That's a very sweeping generalization. Strictly speaking it will be the US Congress who puts US taxpayers money into it.

At present I think the USAFRL study provides a strong case to US readers that the technology works.
[/quote]

You may not approve, but I would like to make a "sweeping generalization" by saying that the Skylon/Sabre-engine technology may be the proverbial "silver bullet" that space-travel enthusiasts/fans have been waiting for for decades.
At least for travel from ground to LEO and back.
For the proverbial "silver bullet" for space-travel and space projects beyond LEO to deep space?  Skylon is not the answer to that need, but maybe that sensationalized EM Drive I've read about recently (if it works) may fit
hand-in-glove with Skylon to revolutionize space-travel completely. When was the last time "REVOLUTIONIZE" has been used authentically and verifiably to describe new/advanced  tech developments for space-travel? 
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/30/2015 05:43 pm
LM have the SR-72 concept which is looking for a pair of engines. The thing is these prototype programs can often end up black budget items where it's hard to see what's happening with them.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/30/2015 06:57 pm
LM have the SR-72 concept which is looking for a pair of engines. The thing is these prototype programs can often end up black budget items where it's hard to see what's happening with them.
No they are not.  They have partnered with Aerojet Rocketdyne for a turbo ram/SCRamjet  engine.

LM think they already have an engine for their concept (and it's nowhere near cutting metal at this point).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/30/2015 08:32 pm

LM have the SR-72 concept which is looking for a pair of engines. The thing is these prototype programs can often end up black budget items where it's hard to see what's happening with them.
No they are not.  They have partnered with Aerojet Rocketdyne for a turbo ram/SCRamjet  engine.

LM think they already have an engine for their concept (and it's nowhere near cutting metal at this point).

Concepts can change. As you've just pointed out this whole thing is a paper exercise at this point so there's nothing stopping things being altered at this time.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: livingjw on 07/30/2015 10:32 pm
If we assume that the engine works as advertised, what is it good for. It cannot possibly do SSTO while airbreathing to only Mach 5 without extremely advanced materials. A TSTO reusable design can be more easily accomplished with a TSTO rocket or rocket boosted Scramjet. So what mission would it do better than some other technology? I really don't understand the fascination with this cycle, which dates back to the 1960's.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: QuantumG on 07/30/2015 10:41 pm
Welcome to the forum livingjw.. I see you've taken Jon Goff's advice on learning about things on the Internet.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/30/2015 11:24 pm
Welcome to the forum livingjw.. I see you've taken Jon Goff's advice on learning about things on the Internet.
Neatly demonstrates why I didn't persist with getting the free logon to AV&ST.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 07/31/2015 02:15 am
@Livingjw

Ooow, you came in with a howler of a poor question there as a first post.

As a starter, check out reaction engines website: http://www.reactionengines.co.uk/

But as a quick answer to your question, the SABRE engine is a dual air-breathing AND rocket engine. The air-breathing cycle has a rather nifty and advanced heat-exchanger to stop things melting. If it performs to expectations, SABRE should do SSTO.


Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/31/2015 11:28 am
Skylon is:
Quote
“very risky as a first application,”
“Sabre may provide some unique advantages in more manageable two-stage-to-orbit configurations.”
(Hellman, AFRL)
SABRE is designed to do one job. Get the vehicle it's attached to from a standing start on a runway to Low Earth Orbit.

If they didn't want that they should have said so and asked either for a hypersonic cruise engine like LAPCAT (which is very different internally) or the HX technology to put on the front of a turbofan.

It seems they either didn't realize how closely this is tied into the use of LH2 or they didn't really believe it could work at all.  Unfortunately now they've run the analysis themselves they now realize it can, and they're not sure what to do about it.  :(
Quote
(Sam Hutchison, Reaction Engines)

Quote
“Enough people now say the Sabre cycle works and it looks compelling. Now the question is what will we do with it?“ As an engine class, it straddles both air and space, so we have to optimize a system to take advantage of that for a given application. As we structure the development plan going forward, we can figure out what the first use is going to be. So over the next six months we will be closing in on that application.”

“Right now we are in the process of scoping that demonstration engine in terms of what it needs to achieve,”

“The key thing is to tick the boxes in every area it needs to tick. It is all about making sure the demonstrator meets the performance requirements that are set for it. We want to make sure it really works and offers the sort of performance that we say it can do. We’re still in that phase. The studies are in their infancy for the engine demonstrator but we have got to make sure we’re not biting off too much more than we can chew.”

(Hutchison)

Are you sure this guy works for REL? That's just amazingly lukewarm. I'd guessed REL had a pretty good idea of what they needed the demonstrator to demonstrate.
Quote

Apparently the demonstrator is on track to do a full engine test in  2018/2019.

Ground testing is possible :
Quote
“because the engine uses the atmosphere as the source of its energy and the reaction mass. And because of the clever heat-exchanger technology, we can modulate the air so the turbomachinery in the engine doesn’t know it is on the ground.”
(Hutchison) 

They plan to simulate higher velocity air by raising the temperature of the air entering the inlet. They are also going to do wind tunnel tests with the inlet.

The AFRL suggest that they might do Mach 5 tests in a high temperature wind tunnel.

There are apparently no short term funding shortfalls.
The precooler (and it's frost control) were a)The thing that lets the engine see near constant inlet conditions from 0 to M5.5, so allowing you to design an efficient engine for a fairly narrow operating range, instead of a one size fits all, to be adequate over the whole range, and b) The one thing that had never been fully tested.

The point I note is that patents can tell you that if you make a HX of a certain size with tubes of a certain size and frost control working a certain way it will let you do certain things.

But they don't tell you how to do those things.

I sincerely hope those matters stay within REL.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 07/31/2015 01:46 pm
Sam Hutchison
**As we structure the development plan going forward, we can figure out what the first use is going to be.**

That sounds like a really odd thing for someone from REL to say. Was he thinking one thing and said another. I thought they knew what the first use of the SABRE was going to be. I thought they had designed it from the start to be an SSTO. Nothing else. Not a sub-orbital whatever, or a high-Mach quick reaction craft for USAF.  wtf?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 07/31/2015 02:22 pm
Sam Hutchison
**As we structure the development plan going forward, we can figure out what the first use is going to be.**

That sounds like a really odd thing for someone from REL to say. Was he thinking one thing and said another. I thought they knew what the first use of the SABRE was going to be. I thought they had designed it from the start to be an SSTO. Nothing else. Not a sub-orbital whatever, or a high-Mach quick reaction craft for USAF.  wtf?
It might be helpful to remember that Sam Hutchison is Director of Corporate Development at REL and  CEO of Skylon Enterprises Ltd so from his perspective he's probably saying that they've got this great piece of technology that they're going to build a SSTO with but which can usefully be applied to a bunch of other tasks on a quicker time frame at lower costs with a small amount of effort on their part so they're in the process of working out which use cases are worth pursuing in order to generate income while they work on Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 07/31/2015 02:32 pm
Skylon is:
Quote
“very risky as a first application,”
“Sabre may provide some unique advantages in more manageable two-stage-to-orbit configurations.”
(Hellman, AFRL)
SABRE is designed to do one job. Get the vehicle it's attached to from a standing start on a runway to Low Earth Orbit.

If they didn't want that they should have said so and asked either for a hypersonic cruise engine like LAPCAT (which is very different internally) or the HX technology to put on the front of a turbofan.

It seems they either didn't realize how closely this is tied into the use of LH2 or they didn't really believe it could work at all.  Unfortunately now they've run the analysis themselves they now realize it can, and they're not sure what to do about it.  :(
Could you explain  perhaps exactly how you see SABRE 4 and Scimitar as very different internally? To my eyes SABRE 4 seems Scimitar inspired.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 07/31/2015 08:16 pm
As we structure the development plan going forward, we can figure out what the first use is going to be. So over the next six months we will be closing in on that application.”

“Right now we are in the process of scoping that demonstration engine in terms of what it needs to achieve,”
ly hope those matters stay within REL.

It does sound a bit disappointing. It reads like might be getting guided by partners (the USAF?) as to what prototype they build to suit partner requirements. Maybe that seems the best reliable place they can get the money from for their prototype. Still that might turn out to be a great technology demonstrator flight application that might actually get built and prove the technology much quicker than any of us hoped - which wouldn't in itself be a bad thing.... it would still be a diversion from the creation of Skylon though which delays the Skylon dream further!
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 07/31/2015 08:56 pm
I'm confident you're reading too much into this. It would be a different matter if Alan Bond said "we're switching to TSTO" publicly, but here you have their Director of Corporate Development sound just exactly like someone in that role should: he's being broadly supportive of the AFRL statement - i.e. their recent partner who they may hope to work with again (read $$$$ that could help further the Skylon project).
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/31/2015 09:01 pm
I'm confident you're reading too much into this. It would be a different matter if Alan Bond said "we're switching to TSTO" publicly, but here you have their Director of Corporate Development sound just exactly like someone in that role should: he's being broadly supportive of the AFRL statement - i.e. their recent partner who they may hope to work with again (read $$$$ that could help further the Skylon project).

How would we know there not still actively working with the USAF, it may not be something the USAF wish broadcasting.

I personally feel if the USAF want a hypersonic vehicle of some type then REL are their best best to achieve this.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 07/31/2015 09:18 pm
I suppose they could be. And that would be one more reason it would be smart to ensure comments made in public are in sync.

(By way of contrast it would not be wise for REL to say "SABRE is for SSTO, if USAF don't get that they're idiots. But we'll take their money anyway.)"

And we may as well remember that the cautious amongst us could be right. An unforeseen performance/mass issue could yet kill hopes of SSTO.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 07/31/2015 10:55 pm
I'm confident you're reading too much into this. It would be a different matter if Alan Bond said "we're switching to TSTO" publicly, but here you have their Director of Corporate Development sound just exactly like someone in that role should: he's being broadly supportive of the AFRL statement - i.e. their recent partner who they may hope to work with again (read $$$$ that could help further the Skylon project).

How would we know there not still actively working with the USAF, it may not be something the USAF wish broadcasting.

I personally feel if the USAF want a hypersonic vehicle of some type then REL are their best best to achieve this.

According to their press release regarding the results of the CRADA it is an ongoing relationship as it states :

"Reaction Engines Ltd. and AFRL are now formulating plans for continued collaboration on the SABRE engine; the proposed work will include investigation of vehicle concepts based on a SABRE derived propulsion system, testing of SABRE engine components and exploration of defence applications for Reaction Engines’ heat exchanger technologies."

Note it states "SABRE derived" regarding what they want to put in a vehicle.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 08/01/2015 06:56 am
It seems to me that there could be a chance for REL to develop something which would not be economically worthwhile  if done by themselves but might be militarily worthwhile to the USAF.

How could one turn up one's nose at a chance to try out some aspects of Skylon/Sabre without needing to go directly to a $10 billion SSTO?  It could be a godsend.

That might control what aspects the engine demonstrator has to be most realistic about, how much money has to be spent on it and where.

Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 08/01/2015 08:28 am
It seems to me that there could be a chance for REL to develop something which would not be economically worthwhile  if done by themselves but might be militarily worthwhile to the USAF.

How could one turn up one's nose at a chance to try out some aspects of Skylon/Sabre without needing to go directly to a $10 billion SSTO?  It could be a godsend.

That might control what aspects the engine demonstrator has to be most realistic about, how much money has to be spent on it and where.

That's my view why turn down money to develop technology that may eventually help you achieve your commercial aims.

My only fear is the USAF 'locking up' some vital technology for their use only.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 08/01/2015 10:11 am
Star One
**My only fear is the USAF 'locking up' some vital technology for their use only.**

That's what I was thinking also. Comments from AFRL suggest that they don't think SSTO is a good or viable option. But they do seem to think that the SABRE technology is useful for them in some other way. They could then have further arrangements with REL to develop certain aspects of the SABRE technology to implement their goals (not SSTO). These technology improvements would become tied up in military/national security concerns and SSTO/Skylon won't happen. At least certainly not in the timeframe as currently envisioned by REL. 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 08/01/2015 10:21 am
At least certainly not in the timeframe as currently envisioned by REL.

Yes. It's the timeframe I find bothersome after waiting (in mine and many people's case) more than 30 years since I was a boy to see Mr Bond's baby fly.

Still if a really good working demonstrator comes out of it, then the belief should be there and it might be full steam ahead for applications after that which wouldn't be so bad. Quite frankly I also want Alan Bond to see his Dan Dare inspired boyhood dreams realised - and superb engineering vindicated - before it's too late!
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 08/01/2015 10:26 am
Star One
**My only fear is the USAF 'locking up' some vital technology for their use only.**

That's what I was thinking also. Comments from AFRL suggest that they don't think SSTO is a good or viable option. But they do seem to think that the SABRE technology is useful for them in some other way. They could then have further arrangements with REL to develop certain aspects of the SABRE technology to implement their goals (not SSTO). These technology improvements would become tied up in military/national security concerns and SSTO/Skylon won't happen. At least certainly not in the timeframe as currently envisioned by REL.
Worrying this, I do hope they have enough experience  dealing with any contracts that AFRL might throw at them that does not tie their hands for future UK development.

But one has to realise they are a business with financial backers that expect a return on their investment.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 08/02/2015 12:11 am
It seems to me that there could be a chance for REL to develop something which would not be economically worthwhile  if done by themselves but might be militarily worthwhile to the USAF.
My only fear is the USAF 'locking up' some vital technology for their use only.

Bond & Co have been down that path before, with their own HOTOL work being locked behind (ultimately pointless) restrictions. I doubt they will go down the same path unless they have an "out" that allows them to continue REL/Skylon when the USAF program is inevitably cancelled.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 08/02/2015 09:00 am

It seems to me that there could be a chance for REL to develop something which would not be economically worthwhile  if done by themselves but might be militarily worthwhile to the USAF.
My only fear is the USAF 'locking up' some vital technology for their use only.

Bond & Co have been down that path before, with their own HOTOL work being locked behind (ultimately pointless) restrictions. I doubt they will go down the same path unless they have an "out" that allows them to continue REL/Skylon when the USAF program is inevitably cancelled.

I wouldn't assume on it being cancelled considering the current political situation.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: banjo on 08/02/2015 10:14 am
Maybe the AFRL have in mind a hypersonic aircraft sporting heat exchangers, carrying a scramjet vehicle to start up speed.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 08/02/2015 12:06 pm

Maybe the AFRL have in mind a hypersonic aircraft sporting heat exchangers, carrying a scramjet vehicle to start up speed.

Who knows there's a lot of rumours doing the rounds these days concerning hypersonic vehicles. The internet is so full of nonsense on the topic thanks to urban legends like Aurora that it is very difficult to sort fact from chaff.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 08/02/2015 12:55 pm
Maybe the AFRL have in mind a hypersonic aircraft sporting heat exchangers, carrying a scramjet vehicle to start up speed.

At the moment scramjets have yet to prove their practical worth and overcome technical difficulties. Considering that, I would have thought that the easiest and cheapest way to get scramjets up to speed is with rockets, as they're doing at the moment. Looking into using SABRE engines to power-up scramjet craft would be a long way down the road (but I guess they could still be considering it).

Putting aside high Mach (6+) capable craft aside, I would have thought that AFRL/USAF would still be interested in a craft that can go from 0-Mach 5 (depending on what the particular goals are). 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ClaytonBirchenough on 08/02/2015 01:45 pm
Maybe the AFRL have in mind a hypersonic aircraft sporting heat exchangers, carrying a scramjet vehicle to start up speed.

At the moment scramjets have yet to prove their practical worth and overcome technical difficulties. Considering that, I would have thought that the easiest and cheapest way to get scramjets up to speed is with rockets, as they're doing at the moment. Looking into using SABRE engines to power-up scramjet craft would be a long way down the road (but I guess they could still be considering it).

Putting aside high Mach (6+) capable craft aside, I would have thought that AFRL/USAF would still be interested in a craft that can go from 0-Mach 5 (depending on what the particular goals are).

SR-72?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: meiza on 08/02/2015 02:07 pm
Maybe the AFRL have in mind a hypersonic aircraft sporting heat exchangers, carrying a scramjet vehicle to start up speed.

At the moment scramjets have yet to prove their practical worth and overcome technical difficulties. Considering that, I would have thought that the easiest and cheapest way to get scramjets up to speed is with rockets, as they're doing at the moment. Looking into using SABRE engines to power-up scramjet craft would be a long way down the road (but I guess they could still be considering it).

Putting aside high Mach (6+) capable craft aside, I would have thought that AFRL/USAF would still be interested in a craft that can go from 0-Mach 5 (depending on what the particular goals are).

SR-72?

Air breathing has more benefits as a cruise technology compared to rockets. Air breathing is speed limited and the engines are heavy. So it makes more sense as a reconnaissance aircraft as a space launcher at first cut.
I hope something comes of this. It's easier to make the technology work if you don't have to take the huge engines, wings, landing gear etc to orbit.

Mach 6 methane fuelled craft have been studied decades ago, attached a picture from the Secret Projects website.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 08/02/2015 02:55 pm

Maybe the AFRL have in mind a hypersonic aircraft sporting heat exchangers, carrying a scramjet vehicle to start up speed.

At the moment scramjets have yet to prove their practical worth and overcome technical difficulties. Considering that, I would have thought that the easiest and cheapest way to get scramjets up to speed is with rockets, as they're doing at the moment. Looking into using SABRE engines to power-up scramjet craft would be a long way down the road (but I guess they could still be considering it).

Putting aside high Mach (6+) capable craft aside, I would have thought that AFRL/USAF would still be interested in a craft that can go from 0-Mach 5 (depending on what the particular goals are).

SR-72?

I wonder if the NASA study into its proposed engines has finished yet.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 08/02/2015 03:00 pm
Maybe the AFRL have in mind a hypersonic aircraft sporting heat exchangers, carrying a scramjet vehicle to start up speed.
You do realize that the idea behind a SCRamjet is to use the heat generated by the air flow at M5 to burn a fuel. REL heat exchangers remove that heat and power a normal engine cycle with it.

SABRE was designed from day one to eliminate SCRamjets because in the late 70's and early 80's it was basically a fantasy technology.

And despite the billions of dollars the USG has pumped into the technology it still is.  :(

I wouldn't assume on it being cancelled considering the current political situation.
Meaning what exactly?
Who knows there's a lot of rumours doing the rounds these days concerning hypersonic vehicles. The internet is so full of nonsense on the topic thanks to urban legends like Aurora that it is very difficult to sort fact from chaff.
And where SCRamjets are concerned there is so much chaff to begin with.  :(

It took a lot of reading to find that an SCRamjet has a listed T/W of 2. The turbojet on the SR71 has a T/W of about 5.3. It's estimated the nacelle halved that to about 2.6.

So after 55 years an SCRamjet may deliver  an T/W almost as good as the SR71 package did in the early 60s.

Once you know that it's no wonder they are having trouble launching even a missile based on this technology.
At the moment scramjets have yet to prove their practical worth and overcome technical difficulties. Considering that, I would have thought that the easiest and cheapest way to get scramjets up to speed is with rockets, as they're doing at the moment.
And yet no one thinks this is quite a big clue that SCRamjets are not a very good design idea.  :(
Every SCRamjet test vehicle has started strapped to a rocket and the rocket has normally got it to starting speed with few hitches.
Quote
Looking into using SABRE engines to power-up scramjet craft would be a long way down the road (but I guess they could still be considering it).

Putting aside high Mach (6+) capable craft aside, I would have thought that AFRL/USAF would still be interested in a craft that can go from 0-Mach 5 (depending on what the particular goals are).
They are but this needs LH2 and armed forces are very wary of cryogenics.
One of the reasons for ending the SR71 is they did not like maintaining the supply chain (a global network of dedicated ground tanks and tanker aircraft) for the JP7 fuel

Not cryogenic. Not toxic. Just not JP4.
LH2 is a much more serious commitment for a unit of reconnaissance aircraft. OTOH as a launcher you could base it at one of the old B36 rated runways, of which the USAF has 3. You'd take a payload hit but you can launch from CONUS and be back at base within a day. Kind of like an orbital B2.

Air breathing has more benefits as a cruise technology compared to rockets. Air breathing is speed limited and the engines are heavy. So it makes more sense as a reconnaissance aircraft as a space launcher at first cut.
A modern turbofan delivers a T/W of 10:1. SABRE's design goal is 14:1. IE about 40% better than a SoA jet engine. That's poor by rocket standards but an Isp 6x or 8x better than the best rocket engine (while air breathing, otherwise it's mere as good as the best Isp of known rocket engines) makes a big difference in building an LV.
Quote
I hope something comes of this. It's easier to make the technology work if you don't have to take the huge engines, wings, landing gear etc to orbit.
Not really.
Firstlyif you've got air breathing your Isp goes up a lot compared to rockets and you can use wings. SABRESkylon is designed to use both. 

Secondly launch puts the airframe at maximum temperature for a very limited period of time. 10s of secs at maximum AB Mach before it goes to full rocket mode and a few 10s of minutes on re entry at most.

Cruise is like re-entry but lasting for hours requiring continual dumping of enormous quantities of heat from the whole airframe. That lets you use design approaches that won't work for long periods but are perfectly acceptable for the launch/reentry mission.

If you don't understand that difference you need to study a bit more engineering.

BTW HTOL takes a thrust roughly 1/3 (or in extreme cases 1/4) the GTOW. OTOH if you go with VTOL the thrust must exceed the weight by a significant amount or there is no take off at all.

Quote
Mach 6 methane fuelled craft have been studied decades ago, attached a picture from the Secret Projects website.
There have been many designs put up by SCRamjet proponents over the years. Various proposals attracted substantial funding. X30 got $Bn+.

All had (in hindsight) low TRL's so IRL it was going to be a case of build the vehicle to test the engine. Which, giving the high levels of uncertainty about M5 combustion and flight meant the probable result was that you'd throw the aircraft away and have to start again.
None have built an actual flight vehicle.

SABRESkylon is designed to avoid as much uncertainty as possible. The engine was designed (from day one) to be tested on the ground, so when you design the vehicle you already know it's going to work. The question then becomes how well can you design the vehicle to deliver that potential.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: banjo on 08/02/2015 04:46 pm

You do realize that the idea behind a SCRamjet is to use the heat generated by the air flow at M5 to burn a fuel. REL heat exchangers remove that heat and power a normal engine cycle with it.


yes, i was thinking of a hypersonic white knight two type carrier aircraft that released a scramjet vehicle once up to speed. 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 08/02/2015 06:05 pm

Maybe the AFRL have in mind a hypersonic aircraft sporting heat exchangers, carrying a scramjet vehicle to start up speed.
You do realize that the idea behind a SCRamjet is to use the heat generated by the air flow at M5 to burn a fuel. REL heat exchangers remove that heat and power a normal engine cycle with it.

SABRE was designed from day one to eliminate SCRamjets because in the late 70's and early 80's it was basically a fantasy technology.

And despite the billions of dollars the USG has pumped into the technology it still is.  :(

I wouldn't assume on it being cancelled considering the current political situation.
Meaning what exactly?
Who knows there's a lot of rumours doing the rounds these days concerning hypersonic vehicles. The internet is so full of nonsense on the topic thanks to urban legends like Aurora that it is very difficult to sort fact from chaff.
And where SCRamjets are concerned there is so much chaff to begin with.  :(

It took a lot of reading to find that an SCRamjet has a listed T/W of 2. The turbojet on the SR71 has a T/W of about 5.3. It's estimated the nacelle halved that to about 2.6.

So after 55 years an SCRamjet may deliver  an T/W almost as good as the SR71 package did in the early 60s.

Once you know that it's no wonder they are having trouble launching even a missile based on this technology.
At the moment scramjets have yet to prove their practical worth and overcome technical difficulties. Considering that, I would have thought that the easiest and cheapest way to get scramjets up to speed is with rockets, as they're doing at the moment.
And yet no one thinks this is quite a big clue that SCRamjets are not a very good design idea.  :(
Every SCRamjet test vehicle has started strapped to a rocket and the rocket has normally got it to starting speed with few hitches.
Quote
Looking into using SABRE engines to power-up scramjet craft would be a long way down the road (but I guess they could still be considering it).

Putting aside high Mach (6+) capable craft aside, I would have thought that AFRL/USAF would still be interested in a craft that can go from 0-Mach 5 (depending on what the particular goals are).
They are but this needs LH2 and armed forces are very wary of cryogenics.
One of the reasons for ending the SR71 is they did not like maintaining the supply chain (a global network of dedicated ground tanks and tanker aircraft) for the JP7 fuel

Not cryogenic. Not toxic. Just not JP4.
LH2 is a much more serious commitment for a unit of reconnaissance aircraft. OTOH as a launcher you could base it at one of the old B36 rated runways, of which the USAF has 3. You'd take a payload hit but you can launch from CONUS and be back at base within a day. Kind of like an orbital B2.

Air breathing has more benefits as a cruise technology compared to rockets. Air breathing is speed limited and the engines are heavy. So it makes more sense as a reconnaissance aircraft as a space launcher at first cut.
A modern turbofan delivers a T/W of 10:1. SABRE's design goal is 14:1. IE about 40% better than a SoA jet engine. That's poor by rocket standards but an Isp 6x or 8x better than the best rocket engine (while air breathing, otherwise it's mere as good as the best Isp of known rocket engines) makes a big difference in building an LV.
Quote
I hope something comes of this. It's easier to make the technology work if you don't have to take the huge engines, wings, landing gear etc to orbit.
Not really.
Firstlyif you've got air breathing your Isp goes up a lot compared to rockets and you can use wings. SABRESkylon is designed to use both. 

Secondly launch puts the airframe at maximum temperature for a very limited period of time. 10s of secs at maximum AB Mach before it goes to full rocket mode and a few 10s of minutes on re entry at most.

Cruise is like re-entry but lasting for hours requiring continual dumping of enormous quantities of heat from the whole airframe. That lets you use design approaches that won't work for long periods but are perfectly acceptable for the launch/reentry mission.

If you don't understand that difference you need to study a bit more engineering.

BTW HTOL takes a thrust roughly 1/3 (or in extreme cases 1/4) the GTOW. OTOH if you go with VTOL the thrust must exceed the weight by a significant amount or there is no take off at all.

Quote
Mach 6 methane fuelled craft have been studied decades ago, attached a picture from the Secret Projects website.
There have been many designs put up by SCRamjet proponents over the years. Various proposals attracted substantial funding. X30 got $Bn+.

All had (in hindsight) low TRL's so IRL it was going to be a case of build the vehicle to test the engine. Which, giving the high levels of uncertainty about M5 combustion and flight meant the probable result was that you'd throw the aircraft away and have to start again.
None have built an actual flight vehicle.

SABRESkylon is designed to avoid as much uncertainty as possible. The engine was designed (from day one) to be tested on the ground, so when you design the vehicle you already know it's going to work. The question then becomes how well can you design the vehicle to deliver that potential.

I was referring to China's hypersonic weapons development program & the U.S. response to it.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: TrevorMonty on 08/02/2015 07:59 pm
I'm confident you're reading too much into this. It would be a different matter if Alan Bond said "we're switching to TSTO" publicly, but here you have their Director of Corporate Development sound just exactly like someone in that role should: he's being broadly supportive of the AFRL statement - i.e. their recent partner who they may hope to work with again (read $$$$ that could help further the Skylon project).

How would we know there not still actively working with the USAF, it may not be something the USAF wish broadcasting.

I personally feel if the USAF want a hypersonic vehicle of some type then REL are their best best to achieve this.

According to their press release regarding the results of the CRADA it is an ongoing relationship as it states :

"Reaction Engines Ltd. and AFRL are now formulating plans for continued collaboration on the SABRE engine; the proposed work will include investigation of vehicle concepts based on a SABRE derived propulsion system, testing of SABRE engine components and exploration of defence applications for Reaction Engines’ heat exchanger technologies."

Note it states "SABRE derived" regarding what they want to put in a vehicle.
The heat exchanger technology has a lot of ground based and probably marine applications. REL are expecting to make a lot of money from this technology alone.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 08/03/2015 04:19 am

You do realize that the idea behind a SCRamjet is to use the heat generated by the air flow at M5 to burn a fuel. REL heat exchangers remove that heat and power a normal engine cycle with it.


yes, i was thinking of a hypersonic white knight two type carrier aircraft that released a scramjet vehicle once up to speed.

I have wondered if a hypersonic vehicle that could go nearly as fast as a scramjet would make a useful test bed.  At the moment the engine+vehicle is lost after use and that has to be quite expensive.   lets say a sabre(lite)-based vehicle can only go up to M5 - perhaps it is still useful to be able to test a scramjet in real flight conditions at that speed.   You can do your test flight, recover the engine, look at what might be wrong with it and then go out and do the test again.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 08/03/2015 05:17 pm

You do realize that the idea behind a SCRamjet is to use the heat generated by the air flow at M5 to burn a fuel. REL heat exchangers remove that heat and power a normal engine cycle with it.


yes, i was thinking of a hypersonic white knight two type carrier aircraft that released a scramjet vehicle once up to speed.
Only if  you're looking for funds for a SCRamjet research programme.  :(

If you want an M5 cruise engine REL did the conceptual work for this under the EU LAPCAT programme.

The simple fact is that REL's work eliminates the need for a SCRamjet in the first place.

Do you want a vehicle that can run at M5 or do you want a SCRamjet research programme?

REL could provide the engine for the former, but have no interest in the latter.  :(
I was referring to China's hypersonic weapons development program & the U.S. response to it.
The thing that needs an ICBM to get it up to speed and then glides to target?

Like the Bell BOMI concepts of the 1950s?

Or the "Evader" MIRV tests of the 1970's & 80's? Which (had they been deployed) would have been nuclear armed by default.

AFAIK the only people "worried" about this are people whose presentation ends "And that's why we need an X $Bn hypersonics research programme to investigate what we can do about it."

On a personal note you should take a look at how this site quotes stuff. Most of what  you quoted in my post was not needed.  :(
I have wondered if a hypersonic vehicle that could go nearly as fast as a scramjet would make a useful test bed.  At the moment the engine+vehicle is lost after use and that has to be quite expensive.   lets say a sabre(lite)-based vehicle can only go up to M5 - perhaps it is still useful to be able to test a scramjet in real flight conditions at that speed.   You can do your test flight, recover the engine, look at what might be wrong with it and then go out and do the test again.
Alternatively use the SABRE derived vehicle instead of the SCRamjet?

This is the problem for REL and the USAF.

HX technology does not help you make a working SCRamjet, which is the dream the vast majority of us researchers have been pursuing.

It eliminates the need for such an engine at all, if you can live with running on LH2.

OTOH the LAPCAT study noted that a design could support a 20 000 Km range without aerial refueling, so (in principal) eliminating the need for the fueling infrastructure that was a big part of SR71 operations.

REL engine concepts don't work if you
a) Can't accept LH2 as the fuel, because  you just don't like it.  b) Need a very long range in a small form factor.

Outside of this their engine concepts can deliver long range and high speed, potentially from bases solely inside CONUS.

That really just leaves long range missiles, not as a test bed but as the sole use for a SCRamjet running on something other than LH2, provided the spec needs a range that far exceeds a pure rocket and the speed exceeds what a subsonic combustion ramjet can do (except that in the 1960's the French built ramjets that did hit M5 and some US test missiles went that fast due to stuck fuel valves).

You'd have to write a very carefully worded missile procurement spec so that the prime candidate for propulsion was an SCRamjet.  :(

US Hypersonics researchers have proved remarkably adept at getting the US Govt to spend several $Bn over the decades with remarkably little to show for it.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: banjo on 08/03/2015 09:23 pm
john i meant only exactly what i wrote.  "maybe the AFRL have in mind......"   
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 08/04/2015 06:46 am
john i meant only exactly what i wrote.  "maybe the AFRL have in mind......"
Then  I would say it's a pretty doubtful notion, given the history of SCRamjet development.  :(

The question again is why?

The rule of thumb (not sure if anyone's tried it with SCRamjets) is ramjets can have a 3 Mach operating range so maybe you can get a vehicle to M8?
Or perhaps you don't like LH2 for a cruise vehicle. Unless you run on straight JP4 you're back to the separate fuel supply chain the SR71 had which was one of the reasons the USAF gave for retiring it in the first place. 

People may think a non LH2 fueled vehicle will be "stealthier" as it will be smaller but most of the features of low radar cross section that worked on an SR71 would scale up quite well.

But whatever the size of such a vehicle it will always be a huge target on any kind of infra red sensor.   :(

Someone sees a  UFO on IR traveling at M5 on a straight and level course at  FL800. They are not thinking "meteorite."
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 08/05/2015 06:45 pm
This is not directly Skylon/SABRE related, but since LAPCAT and Ramjets have been discussed recently:

"Concorde Mark 2: Airbus files plans for new supersonic jet - New jet could cut flight time from London to New York to just one hour"

http://www.telegraph.co.uk/finance/newsbysector/industry/engineering/11782446/Concorde-Mark-2-Airbus-files-plans-for-new-supersonic-jet.html

Animations here:
https://www.youtube.com/watch?v=0dyrbRGkVKI
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Crispy on 08/05/2015 06:58 pm
Already a thread in this forum
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 08/05/2015 07:57 pm
I have just finished reading the latest article in Aviation Week focusing on the Sabre demonstrator engine.

It's interesting to note the comments from both AFRL and Sam Hutchison director of corporate development at Reaction Engines. AFRL state that the Sabre's original target, a single-stage-to-orbit space vehicle remains technically "very risky as a first application," but he go's on to say "Sabre may provide some unique advantages in more manageable two-stage-to-orbit Configurations." Sam Hutchison states  it might be the best approach to demonstrate the technology by taking it one step at a time.

Could this be a step change in Reaction Engines thinking in going for a full blown Skylon Demonstrator, and they now think that's just "a bridge to far"

Might a demonstrator be built  just to prove Sabre up to Mach 5 prior to change over to normal rocket operations be best, the vehicle could be built on a much simpler and smaller  airframe and the return re-entry temperatures would be considerably lower. Once confidence had been achieved it might be possible to modify the demonstrator to achieve crossover to rocket power using a small internal Lox tank to test this, it only needs to operate for a short time so re-entry temperatures will again be  considerably lower than de-orbit temperatures.

I know Sabre can be fully tested at ground level, but to go straight to a flight model Skylon will be a massive risk, no one should  underestimate the complexities involved in this.

In the meantime (to make the financial backers happy) it seems that there are many other  potential aerospace applications beyond just the precooler concept that is the heart of Sabre. This could prove to be a massive income earner for Reaction Engines giving the company the income to create a world-beater in Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 08/05/2015 10:35 pm
@Hankelow8
Yes, this point was mentioned 2 pages back. Why did an REL person say this.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: AnalogMan on 08/13/2015 12:09 pm
Came across this recent NASA Ames conference paper on Skylon that I thought might be of interest to followers of this thread.

Skylon Aerodynamics and SABRE Plumes
20th AIAA International Space Planes and Hypersonic Systems and Technologies Conference
6-9 July 2015, Glasgow, Scotland, United Kingdom


Abstract:
An independent partial assessment is provided of the technical viability of the Skylon aerospace plane concept, developed by Reaction Engines Limited (REL). The objectives are to verify REL’s engineering estimates of airframe aerodynamics during powered flight and to assess the impact of Synergetic Air-Breathing Rocket Engine (SABRE) plumes on the aft fuselage. Pressure lift and drag coefficients derived from simulations conducted with Euler equations for unpowered flight compare very well with those REL computed with engineering methods. The REL coefficients for powered flight are increasingly less acceptable as the freestream Mach number is increased beyond 8.5, because the engineering estimates did not account for the increasing favorable (in terms of drag and lift coefficients) effect of underexpanded rocket engine plumes on the aft fuselage. At Mach numbers greater than 8.5, the thermal environment around the aft fuselage is a known unknown−a potential design and/or performance risk issue. The adverse effects of shock waves on the aft fuselage and plume-induced flow separation are other potential risks. The development of an operational reusable launcher from the Skylon concept necessitates the judicious use of a combination of engineering methods, advanced methods based on required physics or analytical fidelity, test data, and independent assessments

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150015818.pdf (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150015818.pdf)

[Copy also attached]
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 08/13/2015 07:39 pm
Came across this recent NASA Ames conference paper on Skylon that I thought might be of interest to followers of this thread.

Skylon Aerodynamics and SABRE Plumes
20th AIAA International Space Planes and Hypersonic Systems and Technologies Conference
6-9 July 2015, Glasgow, Scotland, United Kingdom


http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150015818.pdf (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150015818.pdf)

[Copy also attached]
Interesting report.

Note this suggest REL have been in contact with the NASA team for years before this came out.

Obvious points.

NASA's analysis is that REL figures for lift and drag are conservative and underestimate how good the design is.

While quite a detailed CFD it assumes pefect gas effects, which is very isleading at these temperatures and pressures. Typicially air at this temp dissociates into atoms and there is some ionization.

I'd suggest it sound quite positive within the limits of what's being simulated and how it's being simulated.

It's a good reminder there are still substantial unknowns to the design, some of which will be quite subtle, although the report points out fuselage heating by the engine plumes is a known unknown, and this works starts to quantify it.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 08/14/2015 02:28 pm
This looks slightly alarming at Mach 12:

https://lh3.googleusercontent.com/UPElrgfWT-BGhP_sXkswAhG09EMvb829njzzXAPWoik=w1130-h826-no

Can the silicon carbide take it? Could it be actively cooled? Hmm.. I suppose re-entry can't be all that cool but can it compare with this?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hanelyp on 08/14/2015 03:05 pm
This looks slightly alarming at Mach 12:

https://lh3.googleusercontent.com/UPElrgfWT-BGhP_sXkswAhG09EMvb829njzzXAPWoik=w1130-h826-no

Can the silicon carbide take it? Could it be actively cooled? Hmm.. I suppose re-entry can't be all that cool but can it compare with this?
Hard to tell how bad that is without a temperature scale or indication of thermal flux.  The exhaust flow is well expanded by the time it impinges on the after-body.  Heat flow to the skin from this flow should be a small fraction of what the combustion chamber and exhaust nozzle need to deal with.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: chipguy on 08/14/2015 04:34 pm

NASA's analysis is that REL figures for lift and drag are conservative and underestimate how good the design is.


I think if you look more closely you'll find that REL figures were conservative at some speeds and optimistic
at others. Another important take away is the thermal flux on the tail is considerable and probably higher
than REL was counting on. Addressing it may cut into margin reserve for mass growth.

However, on the whole the paper represents an important independent assessment of their vehicle concept
and its general agreement with REL's claims should enhance their credibility.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: antiquark on 08/14/2015 04:46 pm
This looks slightly alarming at Mach 12:

https://lh3.googleusercontent.com/UPElrgfWT-BGhP_sXkswAhG09EMvb829njzzXAPWoik=w1130-h826-no

Can the silicon carbide take it? Could it be actively cooled? Hmm.. I suppose re-entry can't be all that cool but can it compare with this?
Hard to tell how bad that is without a temperature scale or indication of thermal flux.  The exhaust flow is well expanded by the time it impinges on the after-body.  Heat flow to the skin from this flow should be a small fraction of what the combustion chamber and exhaust nozzle need to deal with.

In the article they say "there are regions where static temperatures are roughly 8-16 times greater than the freestream temperature."  However I don't know how to fill in the blanks to arrive at an actual temperature value.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alpha_Centauri on 08/14/2015 08:43 pm
State aid: [European] Commission approves £50 million UK support for the research and development of an innovative space launcher engine.

http://europa.eu/rapid/press-release_IP-15-5495_en.htm

How nice of them.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 08/14/2015 09:00 pm
At Mach 12, Skylon C1 was at about 62 km, implying an atmospheric pressure of about 15 Pa and a freestream temperature of something like 240 K.  At Mach 17, it was at around 71 km, implying 4 Pa and 215 K.  Real gas effects tend to result in lower stagnation temperatures (and higher stagnation densities) than one would calculate from the ideal gas law.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 08/14/2015 09:16 pm
It is curious that the authors didn't take the next step and calculate temps on structures. They're clearly aware that this could be the undoing of Skylon - or the retirement of a critical known risk. In the Takeaway section they state: "If the aft fuselage heating owing to nacelle plumes is an issue that cannot be addressed with appropriate structures and materials, then the overall design of Skylon needs to be modified." By which they appear to mean moving the engines aft (and closer to the HOTOL problems.)

They also make a suggestion I don't really follow: Use Skylon as stage 1 in a TSTO system, launching the second stage from the payload bay at ~7 km/s. But wouldn't plume heating be already high at this speed?

The TSTO comment is curiously consistent with the message from USAF/AFRL, so it makes you wonder if there is some connection.
________
For those new to the forum, this was discussed a little three years ago: http://forum.nasaspaceflight.com/index.php?topic=24621.msg943964#msg943964
http://forum.nasaspaceflight.com/index.php?topic=24621.msg945702#msg945702
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 08/14/2015 10:43 pm
Could the plume impingement be mitigated by switching to having a single large expansion ratio nozzle (400:1)   in each SABRE rather than four 120:1 nozzles so that the plumes aren't so  under expanded at high mach and using the airbreathing  nozzle area for thrust augmenting altitude compensation at low mach?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 08/14/2015 11:30 pm
The use of altitude compensating Expansion/Deflection nozzles should help also.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 08/15/2015 12:36 am
As Adrianwyard has nicely reminded us, this topic of plume expansion heating the skylon fuselage was queried on the 1st skylon thread back in 2012. The discussion doesn't seem to have gone any further on the thread and I certainly forgot all about it. But one would have thought that REL has considered this issue. At least I would have hoped they did. There has been no hint of any design modifications to the basic skylon shape nor repositioning of the SABRE engines.

And then the apparently odd comments from the AFRL labs and an REL employee (Sam Hutchison) about using SABRE as a TSTO when the whole original concept was for a SSTO.

I guess there's a lot we still don't know yet.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 08/15/2015 09:51 am
The use of altitude compensating Expansion/Deflection nozzles should help also.

It's only an expansion deflection nozzle in airbreathing mode, in rocket mode it's a 120:1 expansion ratio bell nozzle. Either way an E-D nozzle will still become under expanded once it hits it's critical pressure and the plume will grow.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 08/15/2015 10:42 am

Hard to tell how bad that is without a temperature scale or indication of thermal flux.  The exhaust flow is well expanded by the time it impinges on the after-body.  Heat flow to the skin from this flow should be a small fraction of what the combustion chamber and exhaust nozzle need to deal with.
I wouldn't be so sure. All the heat flow is in the boundary shock wave and their indications of more than 10 times the free stream temperature... However the final gas model will be (they do give compensation estimates for real gas), this is massive, we are talking about a kelvin-scale here!

They will probably have to cool the whole body aft of the wing, I doubt you can passively cool this without adding a lot of mass.

This essentially means there's a significant chance the whole airframe concept is not feasible. It's the kind of risks you run into when designing all-new stuff and venturing into unknown unknowns with a lot of elements in your design.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 08/15/2015 03:51 pm
Assuming plume heating is indeed a problem with D1.5a there's no reason to assume it can't be addressed with relatively simple airframe changes. For example, widening the wing span, moving nozzles further aft, etc.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 08/15/2015 04:01 pm
The use of altitude compensating Expansion/Deflection nozzles should help also.

It's only an expansion deflection nozzle in airbreathing mode, in rocket mode it's a 120:1 expansion ratio bell nozzle. Either way an E-D nozzle will still become under expanded once it hits it's critical pressure and the plume will grow.

Hmmm, I think your saying the E-D benefit occurs it lower altitudes and so is if no help here; that makes sense.

But the nozzle doesn't know if SABRE is in air-breathing or rocket mode, right? Maybe you simply meant earlier in flight when you said 'It's only an expansion deflection nozzle in airbreathing'?

The exhaust from the bypass burners (air-breathing mode) will affect the plume, but that's turned off by the time we're at the problematic speed & altitude/pressure. 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 08/15/2015 04:56 pm
The use of altitude compensating Expansion/Deflection nozzles should help also.

It's only an expansion deflection nozzle in airbreathing mode, in rocket mode it's a 120:1 expansion ratio bell nozzle. Either way an E-D nozzle will still become under expanded once it hits it's critical pressure and the plume will grow.

Hmmm, I think your saying the E-D benefit occurs it lower altitudes and so is if no help here; that makes sense.

But the nozzle doesn't know if SABRE is in air-breathing or rocket mode, right? Maybe you simply meant earlier in flight when you said 'It's only an expansion deflection nozzle in airbreathing'?

The exhaust from the bypass burners (air-breathing mode) will affect the plume, but that's turned off by the time we're at the problematic speed & altitude/pressure. 

Not quite. The SABRE 4 cycle works by separating the rocket combustion chamber from the airbreathing combustion chamber allowing a high pressure rocket chamber (170 bar) and a low pressure airbreathing chamber ( 12 bar but can be from 6 bar to 20 bar depending on implementation). Each rocket  nozzle consists of a single rocket chamber surrounded  by 3 ( or more depending on implementation) airbreathing chambers, they share a rocket nozzle by having a 30:1 ratio inner nozzle after the rocket chamber throat and then a closable throat fed by the airbreathing chambers followed by a nozzle extension that takes the rocket expansion ratio to 120:1. The upshot being that in airbreathing mode the nozzle acts an E-D nozzle but in rocket mode the airbreathing throat closes and the rocket sees a conventional bell nozzle ( although they are designed to work concurrently to allow for a smooth transition).
My suggestion was to  move to a single large area ratio nozzle and use the airbreathing throat to do TAN as altitude compensation. My second suggestion is to crank the delta wing to increase the wingspan, my third is to consider alternate fuels as the SABRE 4 should allow the rocket mode to work on different fuels to the airbreathing mode and gelled hydrogen could be used for the airbreathing mode, together fuel volume could be slashed creating  a smaller tail.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 08/15/2015 05:05 pm
I wouldn't be so sure. All the heat flow is in the boundary shock wave and their indications of more than 10 times the free stream temperature... However the final gas model will be (they do give compensation estimates for real gas), this is massive, we are talking about a kelvin-scale here!
You're missing a few points.

Firstly the vast bulk of that exhaust will be in the plume. A very small part of it's mass flow will be hitting the aft fuselage.

Secondly this is a point simulation and Skylon is a on launch trajectory. It's outside air pressure is continually falling. That means the plume is growing but also the plume density is falling, lowering the energy of the gas that will hit the aft fuselage.

Being a point simulation you'd miss the integration of temperature involved. You've also missed that a large part of the body is at a much lower temperature and therefor that heat could be moved by a heat pipe arrangement. Such systems were looked at for the Shuttle wing but never flown.

Like the XS 1 you have to ask how long does the fuselage have to sustain that temperature. On a M5 cruise vehicle that's hours, but the whole trajectory for Skylon is 10-20min tops.
Quote
They will probably have to cool the whole body aft of the wing, I doubt you can passively cool this without adding a lot of mass.
The report is not detailed enough to make that assumption.
Quote
This essentially means there's a significant chance the whole airframe concept is not feasible. It's the kind of risks you run into when designing all-new stuff and venturing into unknown unknowns with a lot of elements in your design.
Depends on your assessment of how much unknown you're dealing with.

We already know the Shuttle can survive reentry from these kinds of temperatures. No their TPS would not be the preferred option, but an existence proof for survival in horizontal landing from orbital velocity is quite encouraging.

OTOH we didn't know you couldn't build even a reasonably large 2nd stage VTOL stage to survive reentry until someone actually tried it and found they couldn't make it work.

BTW doing a CFD for this size of model takes a lot of computer time, even today. Other posters can probably put some numbers on how long a 6-8 million point model takes to run.

It's a tribute to how far Skylon's design has been matured by REL that they had a CAD model to supply to NASA for this work. I doubt NASA would have looked doing this study a decade ago, given this is a non US vehicle that is not already flying.

Moving to real gas chemistry multiplies that amount of time, so operating at this level of detail is good enough for a (relatively) quick look at the problems.

I will note a few points about the work in general.

1) The Nacelle is fully  closed at anything above M5.5.
2) Likewise ramjet flow (and any burner induced drag) ends when the nacelle closes
3) They use a SSME nozzle, but IIRC that's 1:77, not 1:100
4) It's not an E/D, although above M5.5 I'm not sure there would be much difference.
5) Nozzle form is important. Hempsell alluded to this in a Space Show appearance. A NATO report pointed out that Russian nozzles are differently designed and less prone to flow separation. I'm not sure if the British use the Russian or the Western approach.
6)It's not a "turbo ramjet," that's basically the J58 on an SR71, and a very different thermal
cycle.  IIRC Bill Escher's taxonomy described it as a "Deeply pre-cooled air turbo rocket."

Work like this establishes boundaries for further work, narrowing the risk space. It also shows how subtle the problems can be with a design and puts some boundaries on how serious they are.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 08/15/2015 05:24 pm
Just for reference, the System 2 material can take a maximum of 1470K and the expected maximum temp it should see was 1100K.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 08/15/2015 05:25 pm
The use of altitude compensating Expansion/Deflection nozzles should help also.

It's only an expansion deflection nozzle in airbreathing mode, in rocket mode it's a 120:1 expansion ratio bell nozzle. Either way an E-D nozzle will still become under expanded once it hits it's critical pressure and the plume will grow.

Hmmm, I think your saying the E-D benefit occurs it lower altitudes and so is if no help here; that makes sense.

But the nozzle doesn't know if SABRE is in air-breathing or rocket mode, right? Maybe you simply meant earlier in flight when you said 'It's only an expansion deflection nozzle in airbreathing'?

The exhaust from the bypass burners (air-breathing mode) will affect the plume, but that's turned off by the time we're at the problematic speed & altitude/pressure. 

Not quite. The SABRE 4 cycle works by separating the rocket combustion chamber from the airbreathing combustion chamber allowing a high pressure rocket chamber (170 bar) and a low pressure airbreathing chamber ( 12 bar but can be from 6 bar to 20 bar depending on implementation). Each rocket  nozzle consists of a single rocket chamber surrounded  by 3 ( or more depending on implementation) airbreathing chambers, they share a rocket nozzle by having a 30:1 ratio inner nozzle after the rocket chamber throat and then a closable throat fed by the airbreathing chambers followed by a nozzle extension that takes the rocket expansion ratio to 120:1. The upshot being that in airbreathing mode the nozzle acts an E-D nozzle but in rocket mode the airbreathing throat closes and the rocket sees a conventional bell nozzle ( although they are designed to work concurrently to allow for a smooth transition).
My suggestion was to  move to a single large area ratio nozzle and use the airbreathing throat to do TAN as altitude compensation. My second suggestion is to crank the delta wing to increase the wingspan, my third is to consider alternate fuels as the SABRE 4 should allow the rocket mode to work on different fuels to the airbreathing mode and gelled hydrogen could be used for the airbreathing mode, together fuel volume could be slashed creating  a smaller tail.

Apparently I've not been paying attention because I was not aware that the SABRE 4 design - including this new dual-mode combustion chamber arrangement - had been made public! Was this image from a public document? Patent filing? If so, could you post links? Thanks.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 08/15/2015 05:55 pm
Firstly the vast bulk of that exhaust will be in the plume. A very small part of it's mass flow will be hitting the aft fuselage.
If you mean that due to the fact that only a certain (angular) section of the overall plume hits the body, that's of course, true. What is this, like 10 degrees or so?
If you mean that the bulk of the exhaust is not in the shock front but heading straight aft you are wrong because it's just the nature of the over expanded flow that most of the actual plume mass will be in the shock front because it gets accelerated outwards by the pressure differential. Only a small part will be heading due aft and if my principles of conservation hold that part should not be relevant because at ambient pressure and probably temperature (see the charts) actually _all_ of the plume's thermal energy will be in the shock front.

And given the fact that there is pretty low ambient pressure and mass flow that overall thermal energy will be pretty close to the same as at the nozzle exit because there's not a lot up there the energy could be transferred to.

So I think it's pretty safe to assume that as long as the aft body is indeed within the shock front the thermal energy of the shock front hitting the body will be the same as the thermal energy at the same angular section of the nozzle exit. Which will be significant but should be somewhat easy to calculate if you know the details of the rocket engine.

Quote
Secondly this is a point simulation and Skylon is a on launch trajectory. It's outside air pressure is continually falling. That means the plume is growing but also the plume density is falling, lowering the energy of the gas that will hit the aft fuselage.
So where exactly is all that energy going in your assumption? I don't think you are right with this.

Quote
Being a point simulation you'd miss the integration of temperature involved. You've also missed that a large part of the body is at a much lower temperature and therefor that heat could be moved by a heat pipe arrangement. Such systems were looked at for the Shuttle wing but never flown.
Yes, that's true. I should have made a more precise statement: you can't just radiatively cool it in place unless you use something like the Shuttle TPS (note: I'm not saying the Shuttle's TPS could sustain it, I don't know the amount of heat transfer it could take, as you already mentioned we are talking about pretty low air pressure up there). Transferring the heat to other parts of the body and using these for radiation cooling or absorbing some of the heat using LH2 might work, I don't know.

I don't think something like the Shuttle TPS can be applied without changing the airframe design, BTW, because it will have completely different drag coefficients and will likely change the aerodynamics a lot.

Quote
Quote
This essentially means there's a significant chance the whole airframe concept is not feasible. It's the kind of risks you run into when designing all-new stuff and venturing into unknown unknowns with a lot of elements in your design.
Depends on your assessment of how much unknown you're dealing with.
Not my assessment but the report's.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 08/15/2015 07:04 pm
The use of altitude compensating Expansion/Deflection nozzles should help also.

It's only an expansion deflection nozzle in airbreathing mode, in rocket mode it's a 120:1 expansion ratio bell nozzle. Either way an E-D nozzle will still become under expanded once it hits it's critical pressure and the plume will grow.

Hmmm, I think your saying the E-D benefit occurs it lower altitudes and so is if no help here; that makes sense.

But the nozzle doesn't know if SABRE is in air-breathing or rocket mode, right? Maybe you simply meant earlier in flight when you said 'It's only an expansion deflection nozzle in airbreathing'?

The exhaust from the bypass burners (air-breathing mode) will affect the plume, but that's turned off by the time we're at the problematic speed & altitude/pressure. 

Not quite. The SABRE 4 cycle works by separating the rocket combustion chamber from the airbreathing combustion chamber allowing a high pressure rocket chamber (170 bar) and a low pressure airbreathing chamber ( 12 bar but can be from 6 bar to 20 bar depending on implementation). Each rocket  nozzle consists of a single rocket chamber surrounded  by 3 ( or more depending on implementation) airbreathing chambers, they share a rocket nozzle by having a 30:1 ratio inner nozzle after the rocket chamber throat and then a closable throat fed by the airbreathing chambers followed by a nozzle extension that takes the rocket expansion ratio to 120:1. The upshot being that in airbreathing mode the nozzle acts an E-D nozzle but in rocket mode the airbreathing throat closes and the rocket sees a conventional bell nozzle ( although they are designed to work concurrently to allow for a smooth transition).
My suggestion was to  move to a single large area ratio nozzle and use the airbreathing throat to do TAN as altitude compensation. My second suggestion is to crank the delta wing to increase the wingspan, my third is to consider alternate fuels as the SABRE 4 should allow the rocket mode to work on different fuels to the airbreathing mode and gelled hydrogen could be used for the airbreathing mode, together fuel volume could be slashed creating  a smaller tail.

Apparently I've not been paying attention because I was not aware that the SABRE 4 design - including this new dual-mode combustion chamber arrangement - had been made public! Was this image from a public document? Patent filing? If so, could you post links? Thanks.

Yeah, there were a whole bunch of patents made public in July, among them the heat exchanger frost control patent
(which SABRE 4 no longer uses), the SABRE 3 and SABRE 4  patents and the SABRE 4 nozzle patent. It's probably easiest if you just search back in the thread but this is SABRE 4.
It's interesting in that it is clearly Scimitar derived and the patent is broad enough to cover a SABRE variant with broadly Scimitar performance, save for the subsonic hub fan (see page 23, lines 16-22).

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 08/16/2015 11:35 am
If the work had been done in close collaboration with RE I'd have expected a response, or joint release. Alternately they were aware of it (and how it might affect investment) and this might be why there's been a softening of the response to TSTO suggestions?
And in a company with a better media strategy you'd be right. But REL don't really do media relations.  :(
Quote

It strikes me the plume is mostly going over the top of the craft. Does the simulation assume it will be following the same AoA in this steeper part of the ascent? Is that a reasonable assumption in the higher TWR and Mach phase of the flight?
I'd look a bit closer at those pictures.

I think most of them are plan forms.

BTW AIUI the comment in the 1st para of page 12 is wrong. The NASA calculated l/Cd ratio is betterthan the one REL conservatively estimated. The text does not match the numbers.

I don't think concluding that a TSTO vehicle is the way forward is really something NASA can say, although it sounds like something the USAF would like.

I'd like to see how these results stack up against the one REL got from DLR using their Tau code, which IIRC, does use real gas chemistry.

I will caution that both temperature and time are factors in wheather the vehicle can survive this sort of heating.

Checking the C1 spreadsheet shows that Skylon hits M6.41 45secs after going to full rocket power. It then accelerates to orbital speed over the next 240 secs.

So it has to survive partial immersion in this high temperature fluid for (at most) 4 minutes.

It would seem they need some system to extract the heat from the hot parts of the skin and move it to the colder parts so they can dump it.

Hmm.

Sounds like a kind of heat exchanger to me.

Wherever could REL find someone to design such equipment?

My suggestion was to  move to a single large area ratio nozzle
Judging by the diagram you supplied that's what already happens.
Quote
and use the airbreathing throat to do TAN as altitude compensation.
Assuming the REL E/D works already why would they need to do this? It puts Aerjet's IP in to their critical engine design path.
Quote
My second suggestion is to crank the delta wing to increase the wingspan,
Which gets what?
Quote
my third is to consider alternate fuels as the SABRE 4 should allow the rocket mode to work on different fuels to the airbreathing mode and gelled hydrogen could be used for the airbreathing mode, together fuel volume could be slashed creating  a smaller tail.
Except the SABRE 4 mode already cuts fuel volume needed. In one of their more recent progress reports to the IAS REL stated it's not the LH2 volume that's the problem it's the fuselage needs to be a certain shape and in fact there's a lot of empty  space inside it already.

REL have stated they will sub cool both LH2 and LO2 to below NBP to allow them to operate as no vent tanks on the runway.

You can call it "slush" or "gelled" Hydrogen but the fact remains its a 2 phase mixture of liquids and solids. It's something of a theme of REL's design work that they work very hard not to mix phases. In fact the whole point of the pre cooler is to cool but not to turn  it into a liquid. That is one of the enabling technologies of SABRE. I think the benefits for a 2 phase H2 flow would have to be very  compelling for REL to re-think this. Note that despite it being talked about since at least the mid 60's no vehicle has used it, just as (AFAIK) no engine has used gelled hydrocarbon fuels despite their (potentially) better safety and ability to carry energetic additives.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 08/16/2015 03:53 pm
If the work had been done in close collaboration with RE I'd have expected a response, or joint release. Alternately they were aware of it (and how it might affect investment) and this might be why there's been a softening of the response to TSTO suggestions?
And in a company with a better media strategy you'd be right. But REL don't really do media relations.  :(
Quote

It strikes me the plume is mostly going over the top of the craft. Does the simulation assume it will be following the same AoA in this steeper part of the ascent? Is that a reasonable assumption in the higher TWR and Mach phase of the flight?
I'd look a bit closer at those pictures.

I think most of them are plan forms.

BTW AIUI the comment in the 1st para of page 12 is wrong. The NASA calculated l/Cd ratio is betterthan the one REL conservatively estimated. The text does not match the numbers.

I don't think concluding that a TSTO vehicle is the way forward is really something NASA can say, although it sounds like something the USAF would like.

I'd like to see how these results stack up against the one REL got from DLR using their Tau code, which IIRC, does use real gas chemistry.

I will caution that both temperature and time are factors in wheather the vehicle can survive this sort of heating.

Checking the C1 spreadsheet shows that Skylon hits M6.41 45secs after going to full rocket power. It then accelerates to orbital speed over the next 240 secs.

So it has to survive partial immersion in this high temperature fluid for (at most) 4 minutes.

It would seem they need some system to extract the heat from the hot parts of the skin and move it to the colder parts so they can dump it.

Hmm.

Sounds like a kind of heat exchanger to me.

Wherever could REL find someone to design such equipment?
Active cooling would probably need hundreds of metres of their inconel tubing running underneath the aeroshell ceramic plus another hydrogen/helium heat exchanger and pump for the system. That's going to add a lot of mass. Hence the suggested mass trades to lower the surface area of the tail that needs it.

My suggestion was to  move to a single large area ratio nozzle
Judging by the diagram you supplied that's what already happens.
Nope, SABRE 4 still has 4 nozzles per nascelle, each with an exit area diameter of 1.4m and a expansion ratio of 120:1 for the rocket mode. My suggestion was that with just a  single nozzle  a diameter of up to 4.7m would fit in the same space and have an expansion ratio of up to 1000:1 or higher.  This would be a mass trade against how much active cooling masses but it would have the effect of shortening the time period when the nozzle is underexpanded dramatically and thus the heat soak that the tail experiences as well as lengthening the nacelle mitigating how much of the tail is exposed to the plume and how much the wing is exposed to  plume-induced flow separation.

and use the airbreathing throat to do TAN as altitude compensation.
Assuming the REL E/D works already why would they need to do this? It puts Aerjet's IP in to their critical engine design path.
REL's nozzle uses E/D for the airbreathing mode but the rocket mode is a pure bell nozzle so an extremely large expansion ratio version of it would need some form of compensation to prevent it being grossly under expanded in hypersonic flight,  my suggestion was purely based on the idea that the airbeathing throat already exists so it would only take a connection to the second fuel delivery system to us it for TAN delivery, I wasn't suggesting using Aerojets IP unless they own the very idea of it. However putting an E/D plug in the rocket nozzle might be an better solution.


My second suggestion is to crank the delta wing to increase the wingspan,
Which gets what?
It moves the nacelles further away from the fuselage trading wing mass for active cooling mass.

my third is to consider alternate fuels as the SABRE 4 should allow the rocket mode to work on different fuels to the airbreathing mode and gelled hydrogen could be used for the airbreathing mode, together fuel volume could be slashed creating  a smaller tail.
Except the SABRE 4 mode already cuts fuel volume needed. In one of their more recent progress reports to the IAS REL stated it's not the LH2 volume that's the problem it's the fuselage needs to be a certain shape and in fact there's a lot of empty  space inside it already.

REL have stated they will sub cool both LH2 and LO2 to below NBP to allow them to operate as no vent tanks on the runway.

You can call it "slush" or "gelled" Hydrogen but the fact remains its a 2 phase mixture of liquids and solids. It's something of a theme of REL's design work that they work very hard not to mix phases. In fact the whole point of the pre cooler is to cool but not to turn  it into a liquid. That is one of the enabling technologies of SABRE. I think the benefits for a 2 phase H2 flow would have to be very  compelling for REL to re-think this. Note that despite it being talked about since at least the mid 60's no vehicle has used it, just as (AFAIK) no engine has used gelled hydrocarbon fuels despite their (potentially) better safety and ability to carry energetic additives.
Slush hydrogen and Gelled hydrogen aren't the same things though, slush is a mush of hydrogen ice and liquid while gelled is a mixture of liquid hydrogen and a frozen second fuel, gelled is clearly easier to make and deal with and has safety and boiloff benefits beyond just fuel density.

The Skylon fuselage is shaped for minimum drag and mass, the report we're discussing suggests that their calculations haven't anticipated the drag correctly with regards rocket plume impingement and we've been discussing the mass effects of trying to mitigate such a heat soak, this suggests that maybe with a new design round taking all this into account the fuselage shape needs to change a little. As such maybe Skylon needs to be shorter.

The 60's argument is ironic considering we're talking about  a SABRE powered SSTO here. Slush hydrogen tankage and pumps were successfully built and tested for NASP and generally liquid ice is used industrially as a coolant so the technology for how to pump and tank slush is more mature than you'd think.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 08/16/2015 04:59 pm
How critical is AoA during the latter part of the ascent? At some point the aerodynamic forces become negligible so might you be able to just aim the plume away from structure? (And retain control thanks to the center of mass & pressure being well managed in the Skylon config.) Perhaps even using negative AoA to keep it clear of the vertical stabilizer? Or, as it's a thin moving structure and cooling will be a challenge, move it to the nose - HOTOL style?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 08/17/2015 09:23 am
In 2012 The University of Strathclyde carried out a study for an alternate design for the Skylon airframe , CFASTT-1.
It concentrated on the re-entry heating characteristics of the airframe.

In view of the comments regarding rocket exhaust plume issues , it would be interesting to see if this alternate design improves rocket plume flow.


http://strathprints.strath.ac.uk/41933/1/Brown_et_al_Towards_Robust_Aero_Thermodynamic_Predictions_for_Re_Usable_Single_Stage_to_Orbit_Vehicles.pdf
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 08/17/2015 08:49 pm
In 2012 The University of Strathclyde carried out a study for an alternate design for the Skylon airframe , CFASTT-1.
It concentrated on the re-entry heating characteristics of the airframe.

In view of the comments regarding rocket exhaust plume issues , it would be interesting to see if this alternate design improves rocket plume flow.


http://strathprints.strath.ac.uk/41933/1/Brown_et_al_Towards_Robust_Aero_Thermodynamic_Predictions_for_Re_Usable_Single_Stage_to_Orbit_Vehicles.pdf

Now you mention it, the CFASTT-1 had nacelle's that angle outwards away from the tail; presumably for aerodynamic reasons rather than heating. To my eye the new V-Tails are no closer to the plume than the single C-1 fin, but it's hard to be sure.

I noticed that the NASA Ames paper specifically states that nozzle gimbaling is not taken into account (p6) but that "the plumes are so under-expanded that it is unlikely this will substantially alleviate the impingement effects" (p15). If that's the case, then perhaps we can guess the CFASTT changes will also be of little benefit heating-wise.

And while we're talking of gimbaling, disregard my post from yesterday; I forgot that with Skylon the nozzles are already pointing down rather than straight back, away from the tail and structure.
 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 08/17/2015 09:39 pm
Active cooling would probably need hundreds of metres of their inconel tubing running underneath the aeroshell ceramic plus another hydrogen/helium heat exchanger and pump for the system. That's going to add a lot of mass.
A few A few hundred meters of this tubing will not weigh that much. bigger issues are likely to the thermal conductivity skin material.
Quote
Hence the suggested mass trades to lower the surface area of the tail that needs it.
Yes lowering the surface area is almost always the way to go.
Quote
Nope, SABRE 4 still has 4 nozzles per nascelle, each with an exit area diameter of 1.4m and a expansion ratio of 120:1 for the rocket mode. My suggestion was that with just a  single nozzle  a diameter of up to 4.7m would fit in the same space and have an expansion ratio of up to 1000:1 or higher.  This would be a mass trade against how much active cooling masses but it would have the effect of shortening the time period when the nozzle is underexpanded dramatically and thus the heat soak that the tail experiences as well as lengthening the nacelle mitigating how much of the tail is exposed to the plume and how much the wing is exposed to  plume-induced flow separation.
I think setting the expansion ratio on any launcher is tricky. Pretty much as soon Skylon hits the nozzles "preferred" altitude it will be passing through that pressure altitude.


and use the airbreathing throat to do TAN as altitude compensation.
my suggestion was purely based on the idea that the airbeathing throat already exists so it would only take a connection to the second fuel delivery system to us it for TAN delivery, I wasn't suggesting using Aerojets IP unless they own the very idea of it.
It's patented.  REL would have to license it.
Quote
It moves the nacelles further away from the fuselage trading wing mass for active cooling mass.
Sounds viable. The other option would be to widen the wings to put the final nozzle location as far back as possible. Again I think this needs a detailed look before major design changes are planned.
Quote
Slush hydrogen and Gelled hydrogen aren't the same things though, slush is a mush of hydrogen ice and liquid while gelled is a mixture of liquid hydrogen and a frozen second fuel, gelled is clearly easier to make and deal with and has safety and boiloff benefits beyond just fuel density.
It's still a 2 phase mixture and this is a design approach REL seem very keen to avoid.
Quote
The Skylon fuselage is shaped for minimum drag and mass, the report we're discussing suggests that their calculations haven't anticipated the drag correctly with regards rocket plume impingement and we've been discussing the mass effects of trying to mitigate such a heat soak, this suggests that maybe with a new design round taking all this into account the fuselage shape needs to change a little. As such maybe Skylon needs to be shorter.
Possibly, but the design trades on HTOL vehicles seem much harder than VTOL systems. What you gain on heat reduction you may loose too much control authority as the weight goes too far back, like HOTOL.
Quote
The 60's argument is ironic considering we're talking about  a SABRE powered SSTO here. Slush hydrogen tankage and pumps were successfully built and tested for NASP
Which one? The original NASP of the early 60's or the later X30 of the late 80's?
Quote
and generally liquid ice is used industrially as a coolant so the technology for how to pump and tank slush is more mature than you'd think.
Where LH2 with either SH2 or mixed with something like Methane I doubt anyone has long term experience on any kind of industrial scale.

Again AFAIK it's not the volume of hte propellant. It's putting it in a body that' big enough and trading the surface area. But there it's plum impingement area Vs propellant burn due to higher drag. [EDIT the different elements you can trade are complex, and it's very doubtful you can improve this item and not make any other factor worse, which I think is the difference between design IRL and design in a textbook.  :( ]
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 08/17/2015 11:39 pm
Active cooling would probably need hundreds of metres of their inconel tubing running underneath the aeroshell ceramic plus another hydrogen/helium heat exchanger and pump for the system. That's going to add a lot of mass.
A few A few hundred meters of this tubing will not weigh that much. bigger issues are likely to the thermal conductivity skin material.
Well the Skylon D1 was designed to have 2.5mt of payload margin on top of the various built in structural margins so that's what they have to play with, and if they use it all they won't have anything left for the next problem. Perhaps they will need to re-reconsider the skin, Originally, in the very beginning, they planned to use C/SiC  for the Skylon skin which has a higher maximum temperature (1870K) and a lower density but they switched to System 2 as it was thought to be much cheaper to produce even though it increased the skin mass by 25%. Maybe they need C/SiC for the tail. 

Hence the suggested mass trades to lower the surface area of the tail that needs it.
Yes lowering the surface area is almost always the way to go.
Quote
Nope, SABRE 4 still has 4 nozzles per nascelle, each with an exit area diameter of 1.4m and a expansion ratio of 120:1 for the rocket mode. My suggestion was that with just a  single nozzle  a diameter of up to 4.7m would fit in the same space and have an expansion ratio of up to 1000:1 or higher.  This would be a mass trade against how much active cooling masses but it would have the effect of shortening the time period when the nozzle is underexpanded dramatically and thus the heat soak that the tail experiences as well as lengthening the nacelle mitigating how much of the tail is exposed to the plume and how much the wing is exposed to  plume-induced flow separation.
I think setting the expansion ratio on any launcher is tricky. Pretty much as soon Skylon hits the nozzles "preferred" altitude it will be passing through that pressure altitude.
Absolutely but if you could move the preferred altitude from say 30km to 90km for an acceptable mass/drag  increase then the time the tail sits in the engines plume would fall.  Skylon is , I think, pretty unique among rocket powered craft in having its engines ahead of any structure so while very large expansion ratios haven't previously been thought worthwhile, nobodies had to trade against extra TPS on their fuselage before. Having said that I'm actually doubtful of it mass wise.

and use the airbreathing throat to do TAN as altitude compensation.
my suggestion was purely based on the idea that the airbeathing throat already exists so it would only take a connection to the second fuel delivery system to us it for TAN delivery, I wasn't suggesting using Aerojets IP unless they own the very idea of it.
It's patented.  REL would have to license it.
[/quote]
I thought that their patents would be covering their scramjet derived injection process.

It moves the nacelles further away from the fuselage trading wing mass for active cooling mass.
Sounds viable. The other option would be to widen the wings to put the final nozzle location as far back as possible. Again I think this needs a detailed look before major design changes are planned.
It might also be an idea to angle the nacelles a bit like in the Cfastt-1 design.


Slush hydrogen and Gelled hydrogen aren't the same things though, slush is a mush of hydrogen ice and liquid while gelled is a mixture of liquid hydrogen and a frozen second fuel, gelled is clearly easier to make and deal with and has safety and boiloff benefits beyond just fuel density.
It's still a 2 phase mixture and this is a design approach REL seem very keen to avoid.
They were keen to avoid it in the substance their cooling because it meant they were wasting cooling potential, but they've never had a problem with it on the coolant side, after the hydrogen starts out in the system as a liquid before changing phase to a gas. 


The Skylon fuselage is shaped for minimum drag and mass, the report we're discussing suggests that their calculations haven't anticipated the drag correctly with regards rocket plume impingement and we've been discussing the mass effects of trying to mitigate such a heat soak, this suggests that maybe with a new design round taking all this into account the fuselage shape needs to change a little. As such maybe Skylon needs to be shorter.
Possibly, but the design trades on HTOL vehicles seem much harder than VTOL systems. What you gain on heat reduction you may loose too much control authority as the weight goes too far back, like HOTOL.

Bare in mind that if they need to make two thirds of the tail actively cooled then the tail will be noticeably gaining in weight and the cg will move back anyway.
 

The 60's argument is ironic considering we're talking about  a SABRE powered SSTO here. Slush hydrogen tankage and pumps were successfully built and tested for NASP
Which one? The original NASP of the early 60's or the later X30 of the late 80's?
For the x-30. I distinctly recall it from the book.


and generally liquid ice is used industrially as a coolant so the technology for how to pump and tank slush is more mature than you'd think.
Where LH2 with either SH2 or mixed with something like Methane I doubt anyone has long term experience on any kind of industrial scale.

Again AFAIK it's not the volume of hte propellant. It's putting it in a body that' big enough and trading the surface area. But there it's plum impingement area Vs propellant burn due to higher drag.

For Skylon it's probably not an ideal solution given the fuselage has to fit round a large payload bay  but I had originally been thinking about it for other SABRE use cases, say your the USAF and you have a 1mt 1m3 ISR payload you want to park over anyone anywhere at anytime, what's the smallest SABRE powered vehicle you could make. That kind of thing. For that I think a gelled hydrogen airbreathing mode and a subcooled propane rocket mode could make for a very much smaller vehicle.

I think the paper was pretty convincing that this is an issue but it was less so that they had adequately modelled the SABRE 4 engine and without a model of the actual heat flux the fuselage sees and how it reacts to it it's hard to know how much of an issue it is and if it is then the design trades are going to be very complex.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 08/18/2015 03:01 am
Could do with Hempsell popping his head in right now :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 08/18/2015 10:12 am
I wonder if Reaction Engines could do with their own CFD system so they can put in all the parameters they don't want to tell anyone and then see the actual situation?   

If anything needs to be done it would have to be checked again I would have thought.

... apparently there is this but I have no idea if it would really make sense to use it:
http://www.archer.ac.uk/casestudies/ara_casestudy.pdf

Perhaps it's the expertise that's needed that's the main problem?

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 08/18/2015 11:11 pm
I wonder if Reaction Engines could do with their own CFD system so they can put in all the parameters they don't want to tell anyone and then see the actual situation?   

If anything needs to be done it would have to be checked again I would have thought.

... apparently there is this but I have no idea if it would really make sense to use it:
http://www.archer.ac.uk/casestudies/ara_casestudy.pdf

Perhaps it's the expertise that's needed that's the main problem?



It's probably worth bearing in mind that Reaction Engines today is a considerably larger company than they used to be, they're aiming to have 300 employees by the end of the year ( I believe) and have been hiring all sorts of experts over last two years. They undoubtedly have plenty  of engineers capable with CFD, they've certainly advertised for them, and they've previously commissioned the DLR to do CFD for them.
The upshot of all this is that Reaction Engines today is a whole lot more busy than they used to be and as such they haven't been presenting a lot of conference papers telling us exact what's what like they used to so while they're busy working on the Skylon D1 vehicle definition we largely have to rely on papers up to a decade old to tell us about Skylon construction. For all we know the D1 thermal environment has been properly modelled  and addressed structurally, internally and they just haven't presented a paper on it.
Anyway, with luck there will be some answers in October at the IAC when they present their next progress paper.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 08/20/2015 08:39 am
... apparently there is this but I have no idea if it would really make sense to use it:
http://www.archer.ac.uk/casestudies/ara_casestudy.pdf

Perhaps it's the expertise that's needed that's the main problem?



....

It's probably worth bearing in mind that Reaction Engines today is a considerably larger company than they used to be, they're aiming to have 300 employees by the end of the year ( I believe) and have been hiring all sorts of experts over last two years. They undoubtedly have plenty  of engineers capable with CFD, they've certainly advertised for them, and they've previously commissioned the DLR to do CFD for them.
....
Anyway, with luck there will be some answers in October at the IAC when they present their next progress paper.

Undoubtely - I'm just basically wondering if they will need further help from Ames or if they can do what they need to do in the uk.  Ames has huge computing resources and if that was the limiting factor then experience wouldn't necessarily be able to make up for it.   On the other hand it might be some special code that only Ames knows how to deal with etc etc - I don't know.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 08/20/2015 03:16 pm
... apparently there is this but I have no idea if it would really make sense to use it:
http://www.archer.ac.uk/casestudies/ara_casestudy.pdf

Perhaps it's the expertise that's needed that's the main problem?



....

It's probably worth bearing in mind that Reaction Engines today is a considerably larger company than they used to be, they're aiming to have 300 employees by the end of the year ( I believe) and have been hiring all sorts of experts over last two years. They undoubtedly have plenty  of engineers capable with CFD, they've certainly advertised for them, and they've previously commissioned the DLR to do CFD for them.
....
Anyway, with luck there will be some answers in October at the IAC when they present their next progress paper.

Undoubtely - I'm just basically wondering if they will need further help from Ames or if they can do what they need to do in the uk.  Ames has huge computing resources and if that was the limiting factor then experience wouldn't necessarily be able to make up for it.   On the other hand it might be some special code that only Ames knows how to deal with etc etc - I don't know.

It seems REL has very little trouble gaining access to those sorts of research facility resources given the access to such resources they seem to have had already.
 I think that being located where they are at Culham Science Centre less than 30 mins from Harwell, they probably have more needed resources close by than any other location on the planet what with it being a nexus of so many high tech research facilities and companies enabling the skills and colaborations needed to be often within walking distance. Beyond that there really aren't very many hypersonic research progammes being funded today but there's a bunch of research facilities built to study the area and they'd all probably do research on an active programme that has a chance of flight.
Consider this, NASA published their 2015 draft technology roadmap in May,

http://www.nasa.gov/sites/default/files/atoms/files/2015_nasa_technology_roadmaps_ta_1_launch_propulsion_systems_final.pdf

The Roadmaps are a set of documents that consider a wide range of needed technologies and development pathways for the next 20 years (2015-2035) and under  Technology Area 1: Launch Propulsion Systems, TA 1.3: Air-Breathing Propulsion Systems it says

 "NASA is not currently advancing any technologies applicable for Earth-to-orbit in this area."

If you're a NASA centre with expertise in airbreathing and hypersonics, Skylon seems likely to be the only game in town for the next 20 years if you want to do any work on something that might fly.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: tatarana on 08/20/2015 10:21 pm
Regarding the cooling of the Skylon aft section, there could be a solution mentioned in a previous 2012 study by DLR, 28th  ICAS, attached to this post.
NUMERICAL INVESTIGATION ON THE POTENTIAL OF STEAM COOLING FOR THE SKYLON SPACEPLANE IN HYPERSONIC FLOW, by Th. Eggers

 It uses steam cooling, up to 100 [g/s m2], to achieve a sizeable reduction in local wing temperature.

Making a rough calculation, during 240 s (JS19 !), 20 m2 (wild guess), and 0,1 kg [g/s m2], it gives ~480 kg.
Remember much of this mass could be from water to be used for braking in case of abort, and will have been already launched (but not dumped off). The system to deliver it to the aft section and inserted in the air stream I can not estimate

It seems to me a high mass, but according to  <lkm> "the Skylon D1  was designed to have 2.5mt of payload margin on top of the various built in structural margins...".   

If it can solve this seemingly hard problem, why not ... ???
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 08/21/2015 08:43 am
Remember much of this mass could be from water to be used for braking in case of abort, and will have been already launched (but not dumped off). The system to deliver it to the aft section and inserted in the air stream I can not estimate

It seems to me a high mass, but according to  <lkm> "the Skylon D1  was designed to have 2.5mt of payload margin on top of the various built in structural margins...".   

If it can solve this seemingly hard problem, why not ... ???
Current plans call for dumping the water just after take off as successful take off implies it's no longer necessary.

However that was pre SABRE 4.

Sadly I think your figure on surface are is grossly out. This part of the fuselage is tapering (I think it's a Haak curve so a closed solution for surface area probably exists). But a 5m dia cylinder has about a 15.5m circumference and that section will be more than 1m long. For serious worst case numbers let's say a cylinder 10m long.  That's about 3720Kg of water. which is not good.  :(

Given 1 litre is 1Kg that requires a flow of 15.5litres a minute. For US readers that's about 240 US gallons a minute. With a 10 m/s flow rate that's a 45cm dia pipe. Provided valves are closed gradually water hammer (leading to pressures >3x delivery pressure) should not be a problem.

Clearly shortening the heating time and/or the surface area exposed pay big dividends.  :(

Before anyone gets too  concerned about those numbers please remember.

The rear fuselage is not a cylinder and the affected surface area should be substantially less than a cylinder.

The 240sec rocket flight is from the C1 spreadsheet and should also be substantially shorter for D1.

The figure for payload margin is payload. IOW the design reported in 2010 (provided it works) will deliver 17.5 tonnes, so would have to get a lot worse before it failed to deliver the stated payload of 15 tonnes.

IIRC the mass margin for the vehicle is 15% of empty weight.

BTW re-reading their 2010 progress report to IAC I noted that a goal of trajectory simulation was to keep temperatures during both ascent and descent at or below Shuttle levels.

While I doubt Skylon would fly the the Shuttle mix of tiles and blankets the fact that at no point does it exceed Shuttle skin temperature levels means such a design could use those materials if necessary.

The performance and maintenance cost hits would probably be dire but it does demonstrate that (in principal) a backup plan for the structure does exist and the design team is not "boxed in" if some unknown unknown surfaces with what they are planning to use.

It's little points like that that remind me that REL have spent a long time in studying the problem in  to the best resolution they could muster, and ensuring that where possible there is a backup plan. As funds have permitted they have increased that resolution in order to pick up more issues before construction begins, which is exactly the time you want to find them.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 08/21/2015 05:49 pm
Guys, a few questions that might be useful for an article I plan to write for my blog.

1) Someone said earlier in the thread that 30 people per passenger module is not viable anymore. Do you have different estimates?
2) how would Skylon perform by launching from the arab peninsula? the rationale is that:
- arabs have huge capitals
- arabs are looking actively for new ways to diversify  their oil-based economy
- they already have a very high end turism sector, which could be a perfect complement for a manned Skylon
- they are not so distant from equator


any tought?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 08/21/2015 07:48 pm
@Francesco
People who would potentially pay to go into orbit as a tourist will want to look out the window. Having super Hi-Def internal screens or VR headsets to show what's outside isn't going to cut it for these people, otherwise they could just look at a screen on the ground. Having windows would completely alter the structural integrity of Skylon. Skylon therefore isn't going to be used as a tourist operation. Something else that uses SABRE technology might, but for the moment all that we've ever heard from REL is SABRE/Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RonM on 08/21/2015 08:01 pm
@Francesco
People who would potentially pay to go into orbit as a tourist will want to look out the window. Having super Hi-Def internal screens or VR headsets to show what's outside isn't going to cut it for these people, otherwise they could just look at a screen on the ground. Having windows would completely alter the structural integrity of Skylon. Skylon therefore isn't going to be used as a tourist operation. Something else that uses SABRE technology might, but for the moment all that we've ever heard from REL is SABRE/Skylon.

Tourists wouldn't be able to look out a window during takeoff and landing. However, once Skylon is in orbit and the payload bay doors are open, there is the opportunity for very large windows in the passenger module and a magnificent view.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 08/21/2015 10:53 pm
Ok, so if we're posting numbers now I might as well post mine.
I make the tail area affected by the rocket plume to be approximately  99m2 based on the tail modelled as a Sears-Haack body, which it isn't perfectly, and the thermal image from the paper at Mach 16, which only shows the top and could be larger area than that  at higher altitude.
 
Okay so now things get more  hand wavy and I make no guarantee my maths is right, but the SABRE engines put out  about 6.9Gw with a mass flow of 666 kg. If you imagine that energy spread over the surface area of  cones moving back from the engines then the proportion of the energy intersecting with the tail could be said to be the area of the tail affect/the area of the cones. If that's the case then the tail might be seeing something like 3.3kw/m2 which over the 195 seconds from Mach 8 to orbit could raise the temperature of the skin by around 860K on top of the aerodynamic heating which tops out at 855K for certain parts of the fuselage skin. This is all hand wave and BOE stuff but it seems like a reasonable number. A peak of 1715K might seem bad but the tail probably doesn't seem that much aerodynamic heating and it seems managable with some active cooling or C/SiC. 

Also Skylon carries 1200kg of water for the brakes.                                                                                                               
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 08/21/2015 10:55 pm
@RonM
I guess there is that possibility. But before that happens Skylon will have to become human rated. That might be a little ways off yet.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 08/21/2015 11:59 pm
Ok, so if we're posting numbers now I might as well post mine.
I make the tail area affected by the rocket plume to be approximately  99m2 based on the tail modelled as a Sears-Haack body, which it isn't perfectly, and the thermal image from the paper at Mach 16, which only shows the top and could be larger area than that  at higher altitude.
 
That's about 2/3 of my worst case area estimate.
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Okay so now things get more  hand wavy and I make no guarantee my maths is right, but the SABRE engines put out  about 6.9Gw with a mass flow of 666 kg. If you imagine that energy spread over the surface area of  cones moving back from the engines then the proportion of the energy intersecting with the tail could be said to be the area of the tail affect/the area of the cones. If that's the case then the tail might be seeing something like 3.3kw/m2 which over the 195 seconds from Mach 8 to orbit could raise the temperature of the skin by around 860K on top of the aerodynamic heating which tops out at 855K for certain parts of the fuselage skin. This is all hand wave and BOE stuff but it seems like a reasonable number. A peak of 1715K might seem bad but the tail probably doesn't seem that much aerodynamic heating and it seems managable with some active cooling or C/SiC. 
Another data point may put this number in perspective.

Heat energy released by a modern microprocessor is roughly 100 W/cm^2
As was the thermal rating of the Apollo heat shield.

That's 1 MW/m^2 (laptops use some pretty complex thermal management methods to spread that load so you can (in theory) rest them on you lap and not find scorch marks on  your trousers afterward.

3.3 Kw/m^2 sounds quite viable.


@RonM
I guess there is that possibility. But before that happens Skylon will have to become human rated. That might be a little ways off yet.
Perhaps not as far as you think.

Skylon is completely reusable. What's tested in certification is what will fly. Exactly what was tested, not a new piece built to the same design.

REL have also stated they have no plans to mfg a passenger module however they will accommodate one in the test flights during development if someone builds such a module.

If the flight programme runs 400 flights and the passenger module flies 10 of them and none of them results in a crash would you feel fairly confident the next flight with the module would not either?

Would you feel the same wasy if half the vehicle was newly built and this was its first flight?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 08/22/2015 12:53 am
Regarding the whole rocket plume and the back end of Skylon - any chance of anyone from REL letting us know if this has been looked at and whether it's expected to be a problem?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hanelyp on 08/22/2015 06:24 pm
... If that's the case then the tail might be seeing something like 3.3kw/m2 which over the 195 seconds from Mach 8 to orbit could raise the temperature of the skin by around 860K on top of the aerodynamic heating which tops out at 855K for certain parts of the fuselage skin. This is all hand wave and BOE stuff but it seems like a reasonable number. A peak of 1715K might seem bad but the tail probably doesn't seem that much aerodynamic heating and it seems managable with some active cooling or C/SiC.
3.3kw/m^2 isn't all that much.  Presuming the tail surface was heated by some other source to 855K (and the heat sink calculator I'm using is accurate) that come out to in the neighborhood of 30 degrees extra heating when you account for radiative cooling.  885K doesn't need active cooling with the right materials, or even really exotic materials.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 08/22/2015 11:42 pm
... If that's the case then the tail might be seeing something like 3.3kw/m2 which over the 195 seconds from Mach 8 to orbit could raise the temperature of the skin by around 860K on top of the aerodynamic heating which tops out at 855K for certain parts of the fuselage skin. This is all hand wave and BOE stuff but it seems like a reasonable number. A peak of 1715K might seem bad but the tail probably doesn't seem that much aerodynamic heating and it seems managable with some active cooling or C/SiC.
3.3kw/m^2 isn't all that much.  Presuming the tail surface was heated by some other source to 855K (and the heat sink calculator I'm using is accurate) that come out to in the neighborhood of 30 degrees extra heating when you account for radiative cooling.  885K doesn't need active cooling with the right materials, or even really exotic materials.
Yeah it's a really reasonable number, which is why I was so equivocal about it.
 I calculated it from what seems like an intuitively simple picture of what's going on but the reality must be much more complicated and, as you say, once you factor in radiative cooling then the rate of cooling at 800K is something like 20kw/m2, which basically would make it a non issue which is why I'm somewhat doubtful that there's not something wrong with that number.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Lars-J on 08/28/2015 07:00 am
@RonM
I guess there is that possibility. But before that happens Skylon will have to become human rated. That might be a little ways off yet.
Perhaps not as far as you think.

Skylon is completely reusable. What's tested in certification is what will fly. Exactly what was tested, not a new piece built to the same design.

I'm sorry to inject some reality here, but Skylon is actually none of that, because it does not exist. (yet?) It has not passed a final system design review, no flight hardware has been built, no flight has occurred. It may be *planned* to be completely reusable, but that can be a different thing altogether.

You have more absolute faith in Skylon specifications that REL engineers themselves do.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 08/28/2015 01:29 pm
It may be *planned* to be completely reusable, but that can be a different thing altogether.
I see it's been a while since I mentioned that SABRESkylon is a high cost/risk/reward programme.  Anyone who does not realize this should study the programme more closely.

Like other vehicles it could fail to deliver on it's stated design objectives, much as the X33 and F9R have done.

Unlike both vehicles it's shape is close to that of vehicles that have a)Been designed 1000s of times before (aircraft) and broadly similar to the only 3 designs that have made winged re entries to Earth and the only 2 designs that has made repeated re-entries to Earth (the 2nd being the X37b).

Unlike those vehicles it's trajectory (or flight path for aircraft) is also quite similar to designs  that have flown from runways millions of times before.

All of which suggests (but does not guarantee) That provided the materials deliver their specific properties and the engines deliver their Isp  all "unknown unknowns" will be manageable, as you're (loosely) trying to extend an existing architecture (in terms of shape, flight path and speeds), rather than do a step change on an architecture that was never designed to be reused in the first place.

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You have more absolute faith in Skylon specifications that REL engineers themselves do.
Again not in the sense you seem to mean.  :(

Those who've followed the programme know that in fact Skylon is in it's 4ths re-design (5th if you include HOTOL) as REL have become more detailed in their modelling and more knowledgeable. They have been fortunate that their thinking converged on a design that has not needed radical re-design since originally conceived.

I have absolute faith that both the Reaction Engines and SpaceX design teams will do their very best to make their approaches work.

I have absolute faith both will use the best available models and modelling tools to ensure their plans are viable, or to scrap them and re-design their architecture if they cannot deliver the expected results.

What do you have absolute faith in?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Lars-J on 08/28/2015 03:28 pm
I have absolute faith both will use the best available models and modelling tools to ensure their plans are viable, or to scrap them and re-design their architecture if they cannot deliver the expected results.

I'm glad to hear it, because that is not how you come across when posting.

What do you have absolute faith in?

That change is a constant. And assumptions are often wrong. Among other things. ;)

But in regards to Skylon - based on aerospace history - I have faith in that *IF* Skylon ever flies, it will have some significant differences to the current evolution of the design.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 08/29/2015 07:34 am
I'm glad to hear it, because that is not how you come across when posting.
Like everyone else on any forum, I am responsible for what I write, not for how people read it.

My model for behavior remains Henry Spencer, whose posts always remained polite as well as informative, sometimes in the face of considerable provocation.

Sadly I do not always maintain his high standards.  :(
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That change is a constant. And assumptions are often wrong. Among other things. ;)
Indeed, if you "assume" you do tend to make an ass out of you and me, as the saying goes.  :)
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But in regards to Skylon - based on aerospace history - I have faith in that *IF* Skylon ever flies, it will have some significant differences to the current evolution of the design.
The industry does have a history of over promised specs, under developed tech and under-performing (or non existent, even after $Bn investments) hardware. It is also a truism that key top level design decisions can make or break a project.

The X30 and X33 programmes being master classes of all of those aspects. An SCRamjet engine that after 40+ years of development manages a T/W of about 2? No checking that correct values for certain physical constants were entered correctly?

Let me be clear so you do understand my PoV.

My interest is in anything that lowers the cost per unit mass to LEO in a scaleable  way. The argument "Just launch a 100 tonnes and the price will drop" is pretty much useless to me, since right now most people don't want or need this. It's the same argument used for Ariane 5, Saturn V and SLS (or Ares 5 for it's old name). It only works if the launch rate justifies the up front costs, because it's generally the up front costs that are a nightmare.  I don't know what Areas 5/SLS has spent to date but I do know what' it's put into LEO.

The "We'll cut the cost by 1/2" figure (often touted at start of ELV development) was viewed as useless in the 1950's by Arthur Snitt. I don't expect any change in the market without an 80-90% price cut in the multi tonne to orbit. If you're going to do it I think doing it and having no down mass capability (IE Antares) is pretty much a waste of time. The world does not need yet another  ELV (or semi ELV, which is also what the Shuttle was) with no track record.

I don't care how it's done. I do care if the claims, and how they are planned to be carried out fail even simple cost models. 

The fully reusable F9 looked like it might achieve this 10x reduction. Just to inject some reality here but the first 1st stage F9 recovery has still not happened yet and the architecture will not achieve that price goal for a semi reusable unless SX already mfg F9's with colossal profit margins, IE 200-250% of F9 hardware price.

I think people would have remarked on such an ability, as I don't think it's the normal gross profit margin in aerospace.  :(

I like Skylon because it's developers seem to have factored in the big picture.

It's the only reusable concept that plans to deliver what an equivalent sized ELV can do, does not require the launch provider to carry all the development costs directly (but only because it's designed for full reuse), is sized for the known market and basically gives solid financial reasons for investing in it other than the vanity of the investor.

As a side point when fully funded the team have delivered what they said they would deliver when they said they would deliver it. This is also attractive to investors who are not governments, although it is a reason governments should also invest.

I am equally impressed by XCOR, who have had endured similar trials on their development path and I'd like to see more like all three, but I simply don't. They seem to be the only ones with serious ambition to get to orbit. :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 08/29/2015 02:17 pm
Aren't you contradicting yourself a bit here? If the upfront costs are the problem the RLVs generally look bad, Skylon included.
That's also the reason why there was no way in the world a fully reusable F9 could ever have reduced the launch costs by a factor of 10, the fixed costs are still too high. 50%, maybe, 10% nope.

And that Skylon fudge to split up the business case also won't help, it just moves part of the financial uncertainty beyond the event horizon so that it can easily get forgotten. Problem just is that that doesn't mean it's going away the same way that sticking your head into the sand doesn't make the Lion go away.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 08/29/2015 09:11 pm
The problem they're trying to solve is not the fundamental economic viability of the vehicle.  The problem is getting investment to cover the large up-front development cost.  Balancing that with a relatively near-term payout means the problem of flight rate is pushed off onto operators, who already know the vehicle works once they're called upon to make their decision.  The problem of slow payback is separated from the risk of programmatic failure, which makes the initial investment more attractive.

This is in addition to the distinct possibility that state actors and even some non-governmental entities may well want Skylon for its other characteristics even if they don't necessarily expect to use it often enough to save any money.  And if I recall correctly, REL did say something about selling their first run to government agencies at a higher price, and then dropping the price later for commercial operators...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 08/29/2015 10:36 pm
The problem they're trying to solve is not the fundamental economic viability of the vehicle.

Yes, but that's a totally separate point from the one I was making.
I was talking about the launch cost.

Launch cost has almost nothing to do with development cost, at least not for any "breakthrough" development e.g. technology development (ongoing development costs for things like continuous improvement, adaptation for new requirements etc. are a separate issue and are more like operating costs because they are recurring).
These development costs are sunk costs after the initial development and have no impact on the operating costs and flight costs. Yes, they can ruin your business case (especially overruns) and yes _prices_ may be set pretty high in a hope to recover some of that investment but on the actual launch cost they have no impact.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 08/29/2015 11:51 pm
Aren't you contradicting yourself a bit here? If the upfront costs are the problem the RLVs generally look bad, Skylon included.
I was referring to the up front costs of an ELV 4x-5x bigger than the biggest members of the EELV programme.
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That's also the reason why there was no way in the world a fully reusable F9 could ever have reduced the launch costs by a factor of 10, the fixed costs are still too high. 50%, maybe, 10% nope.
And that's the issue when the builder is the operator as well.
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And that Skylon fudge to split up the business case also won't help, it just moves part of the financial uncertainty beyond the event horizon so that it can easily get forgotten. Problem just is that that doesn't mean it's going away the same way that sticking your head into the sand doesn't make the Lion go away.
And yet that "fudge" is exactly how every other transport system on this planet does business.  :(

While it's true that the way things have been done is not necessarily a good reason for doing it that way in the future the fact that no one else does it the same way it's interesting that ship yards don't run cruise lines, aircraft mfg's don't run airlines (even in countries where this does not break anti-trust laws) or 18 wheeler mfg run haulage companies.

Should that not give people pause for thought that perhaps the way the rocket industry does things is a bit odd and needs to change?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Impaler on 08/30/2015 03:21 am

While it's true that the way things have been done is not necessarily a good reason for doing it that way in the future the fact that no one else does it the same way it's interesting that ship yards don't run cruise lines, aircraft mfg's don't run airlines (even in countries where this does not break anti-trust laws) or 18 wheeler mfg run haulage companies.

Should that not give people pause for thought that perhaps the way the rocket industry does things is a bit odd and needs to change?

In the early days of airplanes and ocean liners that IS what happened, Boeing for example used it's superior designs to run a very anti-competitive airline, government action forced them to stop (and they are still a notorious corrupt company).  The WhiteStar ocean liner company was in a partnership with Harland and Wolff shipbuilders who agreed to not make any ships for WhiteStar's competitors.

The division of manufacturer and operator is always associated with a transportation system becoming, cheap, common, safe, reliable, competitive and regulated.  I don't think anyone disputes that WILL eventually how space travel is done the question is if this vehicle would achieve that kind of market transformation.  Skylon would need to make quantum leaps in all these areas before the ground would be ready for an airliner like division between manufacturer and operator.  It will probably also require a second company making competing substitute vehicles as no operator would run the risk of being completely dependent on a single vehicle supplier.


P.S.  On a technical note, dose anyone think a closed wing https://en.wikipedia.org/wiki/Closed_wing#PrandtlPlane_.28Box-Wing.29 configuration would help Skylon, it would seem to present the possibility of both reducing drag while allowing a higher mounting of the engines thus reducing the need for the bent nacelle (which I assume is needed to keep the thrust through the center of mass which is above the nacelle).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 08/30/2015 08:31 am
In the early days of airplanes and ocean liners that IS what happened, Boeing for example used it's superior designs to run a very anti-competitive airline, government action forced them to stop (and they are still a notorious corrupt company).  The WhiteStar ocean liner company was in a partnership with Harland and Wolff shipbuilders who agreed to not make any ships for WhiteStar's competitors.
Note that word partnership None of the examples you cite were as tightly integrated between the mfg and the operator as most current ELV mfg's are. IIRC TWA and Boeing aircraft were part of the same holding company as was Hamilton Standard (propellers at the time).
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The division of manufacturer and operator is always associated with a transportation system becoming, cheap, common, safe, reliable, competitive and regulated. 
Over a long time scale and that process has barely begun.
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I don't think anyone disputes that WILL eventually how space travel is done the question is if this vehicle would achieve that kind of market transformation. 
Why? [EDIT IOW What pressures are driving that "transformation."  If you're talking about governments in terms of "Get rid of ELV's and lower our launch costs 10x now" the answer is nobody ]

The status [EDIT to be clear I mean the status quo] keeps the people who can already justify launching satellites (or get some government to fund them) launching things already.  As for everyone else they can't afford to launch so (basically) they don't count the the main ELV mfg mind set really could not care less.
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Skylon would need to make quantum leaps in all these areas before the ground would be ready for an airliner like division between manufacturer and operator. 
Depends what you mean by "quantum."

A vehicle that a)Lasts for more than 1 use and b)Does not need have it's structure rebuilt or replaced every time it's used is SOP for every other transport system on the planet, certainly for anything that can move multi tonne weights over 200Km.

Historically people seem to have been thinking that you can gradually evolve to full reusability but SX have demonstrated that does not work. It's a Sow's ear. You can (sort of) make it into something that will hold stuff. It will never be a ladies evening bag for social events.
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It will probably also require a second company making competing substitute vehicles as no operator would run the risk of being completely dependent on a single vehicle supplier.
Hmm. Let me see. I am a government that wants to launch payloads into space on a semi regular basis. Do I
a) Keep handing $60-150m to a foreign business for a ticket with a roughly a 1 in 50 to 1 in 75 chance of being blown to bits that will launch it at their convenience
or
b) Commit to paying quite a lot more (but potentially spread out over a decade or more, roughly $150m/year or 1/120 of NASA's budget) for a vehicle that can launch more or less when we want it to (since it's preped in our country, self ferries to the Equator, get a top up and goes), carries our payload as prime and for a bit extra can give us an upper stage that will allow us to run a Moon or planetary exploration programme.

As a side benefit we can also sell excess capacity to other customers while new projects are in development and if we so choose sell it as an asset (the nearest people come to this is selling either the data from satellites they own or the orbital slots for GEO comm sats)

Decisions, decisions.

BTW this sounds like a discussion US customers would be barred from, but there's nothing to stop a US operator (or part of the US government) buying a Skylon. The real issue would probably be that under US ITAR laws flying down to the Equator would be viewed as "exporting" the payload, even if the Skylon were USG property and therefor (technically) US territory (like Air Force One) and it was simply refueled and loaded with LO2 before take off to orbit.  :(
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P.S.  On a technical note, dose anyone think a closed wing https://en.wikipedia.org/wiki/Closed_wing#PrandtlPlane_.28Box-Wing.29 configuration would help Skylon, it would seem to present the possibility of both reducing drag while allowing a higher mounting of the engines thus reducing the need for the bent nacelle (which I assume is needed to keep the thrust through the center of mass which is above the nacelle).
No. because the heating issue is about plume impingement on the rear fuselage. Your suggestion "fixes" what is currently a non issue as it already has a solution.

What it might address is how to make the next generation of airliners bigger than the 777 or A380. So far the front runner seems to be the Blended Wing Body concept, but this basically eliminates window seats. I don't have an problem with this but apparently people want window seats and the Prandtl design lets them have them, while (in theory) lowering the drag and raising the lift for a given wingspan, which is apparently limited in modern airport design to 80m, and nobody is going to redesign the layout of most of the worlds large airports anytime soon.

That would be a topic for another thread.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 08/30/2015 02:59 pm

And yet that "fudge" is exactly how every other transport system on this planet does business.  :(

Im not saying it's wrong to operate that way. If REL think it's the way to go for them then there is no reason not to use this model - as long as they can find customers.

What I'm saying is that it's not some kind of fairy dust which magically removes a huge amount of cost just by splitting up the business model.

Can you work this way? If you find customers, sure you can.
Can it help to raise mor funds for the overall business? Maybe.
Will it be dramatically cheaper? Nah.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 08/30/2015 03:02 pm
Also "every other in the world" is a bit too high of a call, I know other transport systems operated by their manufacturers.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Vultur on 08/30/2015 07:17 pm
Historically people seem to have been thinking that you can gradually evolve to full reusability but SX have demonstrated that does not work.

This seems like a premature conclusion. Elon Musk has said that FH could be made fully reusable but they want to spend resources on BFR (which will be fully reusable) instead. That doesn't seem to me to rule out a future fully reusable vehicle in the FH class once BFR is developed.

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The real issue would probably be that under US ITAR laws flying down to the Equator would be viewed as "exporting" the payload

What's the self-ferry range? Could it reach Hawaii from the US west coast?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 08/30/2015 07:43 pm
Could it reach Hawaii from the US west coast?

I don't recall if the ferry range has been specified; it was supposed to be "roughly transatlantic" last I recall, but Hawaii is closer to California than Ireland is to Maine.  If it can reach French Guiana from a point in the U.K., Hawaii from Mississippi (never mind California) should be perfectly possible.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Impaler on 08/31/2015 06:26 am

Why?

The status keeps the people who can already justify launching satellites (or get some government to fund them) launching things already.  As for everyone else they can't afford to launch so (basically) they don't count the the main ELV mfg mind set really could not care less.

The Why is blindingly obvious, falling short in the 5 criteria I specified, cheap, common, safe, reliable, competitive and regulated.  If it's not cheap, common, regulated and safe the volume will be too low to justify the manufacture of more then a handful of vehicles and the manufacturer would simply fold after completing them.  If it's not reliable the operator will have to have the manufacturer literally live onsite keeping the vehicle alive at such a high cost that it becomes a de-facto lease rather then a purchase (which while it is a viable business model similar to software, it's not what your describing).  If it's not competitive (aka other manufacturer) then operators will not want to become dependent on a single supplier or will demand an exclusivity agreement with the manufacturer.


Hmm. Let me see. I am a government that wants to launch payloads into space on a semi regular basis. Do I
a) Keep handing $60-150m to a foreign business for a ticket with a roughly a 1 in 50 to 1 in 75 chance of being blown to bits that will launch it at their convenience
or
b) Commit to paying quite a lot more (but potentially spread out over a decade or more, roughly $150m/year or 1/120 of NASA's budget) for a vehicle that can launch more or less when we want it to (since it's preped in our country, self ferries to the Equator, get a top up and goes), carries our payload as prime and for a bit extra can give us an upper stage that will allow us to run a Moon or planetary exploration programme.

As a side benefit we can also sell excess capacity to other customers while new projects are in development and if we so choose sell it as an asset (the nearest people come to this is selling either the data from satellites they own or the orbital slots for GEO comm sats)

Decisions, decisions.


No one will believe any reliability estimate for any radically new vehicle until it has gone through dozens of flights, and if your trying to prove airplane levels of safety and not-blowing-up your looking at hundreds of flights before a buyer would be willing to just plunk down the purchase price and accept the chance of loosing the whole vehicle.

Your switching to talking about government space-agency ownership rather then multi-national commercial, but your explanation contains it's own undoing.  One nation is supposed to buy the thing and then sell the capacity they don't use.  But why doesn't the buying nation just let someone else be the sucker and THEY can buy the spare capacity as need dictates.  Everyone who can't fully utilize a whole vehicle (maybe 2-3 agencies tops) is in the same boat so their is no reason for anyone to get their own, they would rather purchase flights from an international consortium which means your looking at a handful of vehicles for the whole world market which isn't enough to justify the manufacturers business.

Also no national space agency just buys hardware like that from another country, the ALWAYS develop their own capabilities IN HOUSE, even if they are primitive at first.  Because any piece of high technology requires a huge intellectual and manufacturing army to maintain, you can't just buy something and become empowered, you need your own space industry and the best way to do that is to grow it organically.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 08/31/2015 08:16 am
No one will believe any reliability estimate for any radically new vehicle until it has gone through dozens of flights, and if your trying to prove airplane levels of safety and not-blowing-up your looking at hundreds of flights before a buyer would be willing to just plunk down the purchase price and accept the chance of loosing the whole vehicle.

The test programme is ~400 flights with just two vehicles, including a couple dozen abort tests.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 08/31/2015 10:28 am
The test programme is ~400 flights with just two vehicles, including a couple dozen abort tests.

The OP this is a reply to seems to be more of a writer than a reader.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 08/31/2015 10:47 am
What I'm saying is that it's not some kind of fairy dust which magically removes a huge amount of cost just by splitting up the business model.
It does split the pay back into a few big chunks, rather than a great many little ones.
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Will it be dramatically cheaper? Nah.
Based on what?

When there is one operator with one Skylon I don't expect them to charge below market rate (which will not be SX's asking price for any payload > 13 tonnes and for a comm sat will be more like the $100m Shotwell stated SX charge for GTO launches)

Which will recover the cost of buying a Skylon in a fairly small number of launches.

The question becomes what happens when multiple operators are in the field, which is what REL want and need.

Note this excludes governments who want a launch-on-demand capability. From REL's PoV it does not matter  how often they launch, since they've already bought the vehicle and its the customers privilege to when they launch their next payload.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 08/31/2015 10:56 am
Also "every other in the world" is a bit too high of a call, I know other transport systems operated by their manufacturers.
Which are?

The only ones I can think of is the Antonov "Spirit" operated by "Antonov Airlines," and the "Beluga" Airbus parts transporter, which I think is pretty much only used for Airbus business.

Which would just leave every other large aircraft in series production being sold to operators

I'd be very interested to see what vehicles I've missed.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Lars-J on 08/31/2015 09:28 pm
I'm glad to hear it, because that is not how you come across when posting.
Like everyone else on any forum, I am responsible for what I write, not for how people read it.

Then you need to be more precise. Just look at this statement that triggered my comment again:

"Skylon is completely reusable. What's tested in certification is what will fly. Exactly what was tested, not a new piece built to the same design."

How am I supposed to interpret that, other than that you are certain that things will turn exactly this way? In your eagerness to convince people, you have a history of expressing certainty where there is little (or none) to be found. This does not make your arguments more persuasive, it has the opposite effect.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 08/31/2015 11:39 pm
Then you need to be more precise. Just look at this statement that triggered my comment again:

"Skylon is completely reusable. What's tested in certification is what will fly. Exactly what was tested, not a new piece built to the same design."

How am I supposed to interpret that, other than that you are certain that things will turn exactly this way? In your eagerness to convince people, you have a history of expressing certainty where there is little (or none) to be found. This does not make your arguments more persuasive, it has the opposite effect.
Well you could have interpreted it as REL believing and planning for this outcome, since they expect Skylon to fly like an aircraft. Outside the military most aircraft don't have bits designed to routinely drop off and be replaced, like tanks and RATO packs, for example.

Would you feel better if I preface my remarks with "REL have stated that.." ? I'm not really used to dealing with people whose comprehension needs that much guidance regarding whose PoV is being expressed, but perhaps I'll start factoring your problems into my posting style in future.

Normally I take any companies statements at face value as I don't have any special insight into any business. In the same way as I took REL's on flight testing and certification I took Shotwells comments about being able to do a fully reusable F9 launch for $6m in June 2013. That's, in hindsight, now looks to be a case of "expressing certainty where there is little (or none) to be found"  as well.

Like wise when Musk stated in 2014 that no F9 (or F9 derived) vehicle was going to be fully reusable and it would be the "BFR" that would be fully reusable I also take him at his word.

I've seen speculation that SX will "go back" and make a fully reusable FH, but SX have made no such public statements I'm aware of, so why would anyone think that when the CEO just said the reverse?

I merely re-stated what REL plan and expect to be able to do, just as SX have planned and stated what did expect, and now expect, to do.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 09/01/2015 01:09 am
I'm glad to hear it, because that is not how you come across when posting.
Like everyone else on any forum, I am responsible for what I write, not for how people read it.

Then you need to be more precise. Just look at this statement that triggered my comment again:

"Skylon is completely reusable. What's tested in certification is what will fly. Exactly what was tested, not a new piece built to the same design."

How am I supposed to interpret that, other than that you are certain that things will turn exactly this way? In your eagerness to convince people, you have a history of expressing certainty where there is little (or none) to be found. This does not make your arguments more persuasive, it has the opposite effect.

I wish to speak up for John. We know what he means "Skylon AS DESIGNED is completely reusable." This is just pedantry. We'd ALL hate it if everyone had to preface each sentence with some disclaimer or add superfluous words like 'AS DESIGNED' everywhere. We also all know Skylon is much more than a BOTE design or a PowerPoint.

We all get it all already. This is an advanced concepts thread...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Lars-J on 09/01/2015 06:07 am
I wish to speak up for John. We know what he means "Skylon AS DESIGNED is completely reusable." This is just pedantry. We'd ALL hate it if everyone had to preface each sentence with some disclaimer or add superfluous words like 'AS DESIGNED' everywhere. We also all know Skylon is much more than a BOTE design or a PowerPoint.

We all get it all already. This is an advanced concepts thread...

I realize that your mileage may vary at this point, but I don't think it is overly pedantic. This is where advanced concepts are discussed and challenged, not accepted at face value just because somebody makes a claim. 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 09/01/2015 07:11 am

I wish to speak up for John. We know what he means "Skylon AS DESIGNED is completely reusable." This is just pedantry. We'd ALL hate it if everyone had to preface each sentence with some disclaimer or add superfluous words like 'AS DESIGNED' everywhere. We also all know Skylon is much more than a BOTE design or a PowerPoint.

We all get it all already. This is an advanced concepts thread...

I realize that your mileage may vary at this point, but I don't think it is overly pedantic. This is where advanced concepts are discussed and challenged, not accepted at face value just because somebody makes a claim.

I feel I have to chip in here & defend John as well to add that your original comment did indeed smack of pedantry & your explanation here seems to be little more than arm waving in an attempt to defend the point.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 09/01/2015 08:16 am
This is where advanced concepts are discussed and challenged, not accepted at face value just because somebody makes a claim.
On that basis there is a case for all of SpaceX's reusability work to be moved to this section.

Their claims have been accepted at face value and the landing and the landing of high aspect ratio stages (IE Grasshopper) is definitely on the cutting edge of control systems and flight dynamics work.

AFAIK no one seriously doubted their claims to be able to deliver a reusable F9 upper stage, until they stated they couldn't do it and they'll have to upscale to BFR to do so.

Please note "uneconomic" is an effect of the root causes, not the root cause for cancelling F9 upper stage reuse. That will be around the physics of re entry. Yet no one seems to have thought this was going to be a problem for SX.

Hopefully SX will try again before the year is out and succeed, making it an impressive move forward for expendable technology.

But right now I think you put the whole SX reusability effort under "advanced concepts" as well.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 09/01/2015 05:07 pm
Quote
Will it be dramatically cheaper? Nah.
Based on what?
Based on "cost just doesn't go away because you split it up differently". In your own words, you are also more of a writer than a reader, right?

Quote
When there is one operator with one Skylon I don't expect them to charge below market rate
I didn't write about price. I wrote about cost. And I explicitly stated that.

All you are doing over and over again is re-stating your same arguments about risk assignment in the investment process but I wasn't talking about that at all. All of this is completely irrelevant for a long-term business case, only recurring cost is relevant then.
No currently flying vehicle is earning it's initial investment.

How about reading and trying to understand my points instead of just re-iterating the same edge-case maths over and over again.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 09/01/2015 05:28 pm
OK, I'll try to explain it one more time...

A Skylon is an investment good. Whatever irrational stuff single players in the market might be prepared to do at some point, if it's going to work in the long term it needs to earn it's total operating cost. Building the thing. Building the operating infrastructure. Flying the thing and it's infrastructure. Repairing them and replacing them end of life with new ones.
No different cost allocation will make any of these smaller. Yes, one party or the other might throw a subsidy or two in there but the same is happening today with the competition. It#s not going to make the cost any smaller, only sometimes the price.

The question will be: what will that total cost be and how much will it be lower compared to existing solutions.

Figures that are mostly irrelevant here are for example initial development cost for the technology because even if you fail to get them recovered the technology is still there.
But you DO need to count the cost to keep the company building the thing around because they will need to keep the knowledge, build replacements, do continuous improvements and so on. They will also need investment (and operating cost) for equipment to build the things around.

The latter is why there's no way in the world SpaceX's reuse scenario could reduce the launch cost 10-fold or so without a dramatic rise in launch rates, the cost of keeping the whole company around doesn't go away just because the company pretty much doesn't have an awful lot to do every day anymore. That's also the very reason why launch costs increased so dramatically with diminishing launch rates at the end of the cold war. All the technology was already developed and even a lot of the LVs already built but all the infrastructure and people were still needed.

Skylon will be no exception to that. If they sell a handful of the things and launch rates don't increase and they stop building them then the cost to keep the existing ones alive will be high. Because you'll still need an awful lot of that infrastructure and people without revenue from new sales.

A good example is Concorde. When that business case came apart due to the oil price shock the initial investment was completely written off (and covered by governments) yet operating the things was still way more expensive than it would have been in a successful scenario because now the few planes flying around needed a standing army of specialists only servicing so few of them.

No, cost reductions have to go along with launch rate increases and dramatic ones, everything else will not make a difference. Especially not accounting practices.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Space OurSoul on 09/01/2015 06:05 pm
Had we all seen this presentation from a couple months back with Robert Bond (not Alan)?

https://tv.theiet.org/EmbedPlayer.html?id=6789 (https://tv.theiet.org/EmbedPlayer.html?id=6789)

The first 25 minutes is your basic intro to Skylon/SABRE, but at 25 minutes there's what I believe is new information, namely that the sub-scale test pre-cooler contains 16,800 tubes totaling 52km (that is, 52,000m) in length. That's pretty astounding, and for me lends not a small amount of significance to REL's accomplishments scaling precooler module manufacturing to production levels. It also matches well with the previously-stated 2,000 km of tubing in a full-sized SABRE.


Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Space OurSoul on 09/01/2015 06:15 pm
Over in an L2 SpaceX thread, Ronpur50 put together a simple size comparison of some extant launchers with some speculation on the SpaceX BFR:

I had this image of some rockets...

With Ron's permission, I elided the L2 work and added the 273-foot Skylon C1, which I present here. Not a small ship.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Chris Bergin on 09/01/2015 06:18 pm
Heck! I didn't know Skylon was that big!

PS There was a report to mod about posts getting out of hand with the tone. Remember to keep it civil at all times.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Ronpur50 on 09/01/2015 07:01 pm
That is huge!
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: spacenut on 09/01/2015 07:35 pm
Using hydrolox, it makes sense that it is that big.  It has a 12 ton LEO payload capacity, small for it's size, but comparable to Atlas, Delta, and Falcon 9.  Now, what would be the operating costs, and how many times could it be reused?   
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 09/01/2015 07:41 pm
Over in an L2 SpaceX thread, Ronpur50 put together a simple size comparison of some extant launchers with some speculation on the SpaceX BFR:

I had this image of some rockets...

With Ron's permission, I elided the L2 work and added the 273-foot Skylon C1, which I present here. Not a small ship.
It's big.

Perhaps it would help if there was also say a 747-8 (250' 2")  or an A380 (239')  in there.

Good thing it's not a tail sitter, isn't it?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 09/01/2015 08:15 pm
OK, I'll try to explain it one more time...

A Skylon is an investment good. Whatever irrational stuff single players in the market might be prepared to do at some point, if it's going to work in the long term it needs to earn it's total operating cost. Building the thing. Building the operating infrastructure. Flying the thing and it's infrastructure. Repairing them and replacing them end of life with new ones.
I agree if the system is to operate without any government subsidies.

It's interesting to compare SABRESkylon against every other LV to see how they measure up on that scale.
Quote
No different cost allocation will make any of these smaller. Yes, one party or the other might throw a subsidy or two in there but the same is happening today with the competition. It#s not going to make the cost any smaller, only sometimes the price.

The question will be: what will that total cost be and how much will it be lower compared to existing solutions.

Figures that are mostly irrelevant here are for example initial development cost for the technology because even if you fail to get them recovered the technology is still there.
You still persist in thinking this is a government programme. If the costs are not fully recovered the business is insolvent and closes.
Quote
The latter is why there's no way in the world SpaceX's reuse scenario could reduce the launch cost 10-fold or so without a dramatic rise in launch rates, the cost of keeping the whole company around doesn't go away just because the company pretty much doesn't have an awful lot to do every day anymore. That's also the very reason why launch costs increased so dramatically with diminishing launch rates at the end of the cold war. All the technology was already developed and even a lot of the LVs already built but all the infrastructure and people were still needed.
And as long as the only way for the LV mfg to recover their costs is also to launch them that will always be the case. The number of launches they can directly handle (and those staff are also part of the "standing army" who have to be paid)  is a key part of why no other common transport system operates this way. IRL One company builds. Many companies operate them.
Quote
Skylon will be no exception to that. If they sell a handful of the things and launch rates don't increase and they stop building them then the cost to keep the existing ones alive will be high. Because you'll still need an awful lot of that infrastructure and people without revenue from new sales.
But you've failed to explain why that scenarios is any more credible than REL's expectation they will sell enough to break even IE cover their development costs and make profit. Why do REL only manage to sell a handful other than "Because I say so" ?

Basically you're argument seems to come down to "But they might not sell enough of them."

Quote
A good example is Concorde. When that business case came apart due to the oil price shock the initial investment was completely written off (and covered by governments) yet operating the things was still way more expensive than it would have been in a successful scenario because now the few planes flying around needed a standing army of specialists only servicing so few of them.
I don't think we'll be seeing a "Hydrogen" price shock where it rises 4x, as was seen with oil in 1973, when it rose to (gasp) $12/barrel.

Again why do you think that the world (both governmental and non governmental institutions) would collectively say "No, we don't want to own a fully reusable, on demand space access for payloads up to 15 tonnes to LEO. With 2 skylons flying we'll just buy flights when we need them. "

That was basically the UK's rationale for abandoning Black Arrow but I doubt any reasonable government would be so stupid today.
Quote
No, cost reductions have to go along with launch rate increases and dramatic ones, everything else will not make a difference. Especially not accounting practices.
So let's see for your scenario to happen a few Skylons get built but the support charges go sky high because a few Skylons get built and the price per unit mass stays sky high.

Is that roughly correct?

So nobody else lowers their prices?
Nobody else buys a Skylon as well to compete?
The increased support costs due to the small mfg run mean that the rest of the industry can continue to charge it's existing price levels?

A failure rate of <1 in 400 and intact abort (allowing return of payloads following all failed launches) is no marketing advantage to Skylon operators.

You actually believe this to be a credible scenario for how the future market will develop?

Perhaps you could outline the evidence you have to support this outcome?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: tl6973 on 09/01/2015 08:31 pm
Now, what would be the operating costs, and how many times could it be reused?

The operating costs are a subject of great debate on this thread. I have not researched it in-depth enough to form an opinion of my own, but there is an interesting assessment here:

https://freespaceeconomics.wordpress.com/2014/07/31/skylon-special-report-the-operator-business-case/

The author is Francsco Nicoli and has been quite active here so he might be happy to field any further questions you have arising from reading. It's worth pointing out that his economic analysis is split between the business case for operating Skylon and the business case for building Skylon

As for the number of reuses (also a very hot topic), Reaction Engines have stated that the design goal is for 200 reuses per Skylon vehicle
 
Title: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 09/01/2015 09:05 pm
I agree if the system is to operate without any government subsidies.
What have government subsidies to do with all this?

Quote
You still persist in thinking this is a government programme. If the costs are not fully recovered the business is insolvent and closes.
YOU are the only one talking about government all the time.
I'm talking about real-life business.
It's you who's coming up with all these governments buying Skylons without looking at price and cost just to have "assured access", that's not me.

In real life, if a business doesn't fully recover it's initial investment but it's assets are still valuable it gets restructured or sold or the investors pour in more money to keep it alive to not lose everything. Every second construction project works that way and industry is full of companies that have undergone that process. Bought a car one day? The manufacturer might be one of those companies.
Ever flown with an airline? Same.

That's why the initial cost doesn't matter as much as the running cost: If it was too expensive and could not recover the investment: bad day for the investor. If it works well and  not necessarily a bad day for the company.

If it can't recover it's budget and doesn't work or doesn't cover the running cost, that's when companies get shut down.

Quote
But you've failed to explain why that scenarios is any more credible than REL's expectation they will sell enough to break even IE cover their development costs and make profit. Why do REL only manage to sell a handful other than "Because I say so" ?
Where did I say that any scenario is more likely than any other? I wasn't talking about any probabilities or such.

Listen. You either try to understand what I'm saying and I mean the whole message or this has no sense. Picking a single sentence, quoting it out of context, claiming something completely unrelated and postulation that would be a proof for something will lead nowhere.

Quote
Basically you're argument seems to come down to "But they might not sell enough of them."
Sure. because that's the only case where your arguments in favor of why breaking up the business case makes any difference has any relevance.

In the case where they keep churning out a new Skylon every month and these are flying twice a wee each we DO have a dramatic growth in launch rate or what is your idea that all these Skylons are doing? Sitting in backyards for the amusement of investors?

You claim that Skylon works fine business wise without any increase in launch rate meaning they can't sell more than a handful of them, when I point out what that means economically then you claim they would sell more. Sorry, that doesn't compute.

And if they are doing that, if every government just wants to have a Skylon and just fly it once a year then yes, the costs per flight for the Skylon system will be very high. They might still get priced ANYWHERE, just as it is today but the cost will be high.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: momerathe on 09/01/2015 10:23 pm
It's big.

Perhaps it would help if there was also say a 747-8 (250' 2")  or an A380 (239')  in there.

Good thing it's not a tail sitter, isn't it?

a couple of comparison images I've seen previously:

(http://www.armaghplanet.com/blog/wp-content/uploads/2012/08/Image-of-Skylon-and-shuttle-comparison.png)

(http://i.imgur.com/wbrgXygl.jpg)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SteveKelsey on 09/01/2015 10:44 pm
A small plea I make from time to time on this thread

Please can we consider the implications of Skylon for what are currently non-space faring nations-i.e. the majority.

The options for those nations wishing to acquire LEO and beyond are somewhat limited at the present.
A nation can spend money with one of the  incumbents, thereby achieving a limited LEO access at this time, and only if the existing carriers  are happy to provide the service. This is only attractive if you limit your ambition to satellite missions. If you have greater ambition, this route is closed to you.

Or, you can develop your own space access system. This means developing the technical, manufacturing, logistical and operational expertise and the investment in all the infrastructure. This takes time and money- as an example consider the Chinese space program which was given significant assistance from Russia and yet has still taken a couple of decades ( at least) and significant investment to achieve its current level.

Or, you can buy your independent space access system with minimum of 200 launches ready developed for significantly less.

As a launch system Skylon may, or may not be cost competitive with SpaceX at al  for individual launches, I tend to think it will be competitive but this has yet to be proven.  As an independent national  space access system  Skylon is in a market of one and is cheap.  I can imagine that when this becomes clear its market is rather larger than the current paradigm might suggest.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Lars-J on 09/01/2015 11:30 pm
...
Or, you can buy your independent space access system with minimum of 200 launches ready developed for significantly less.

As a launch system Skylon may, or may not be cost competitive with SpaceX at al  for individual launches, I tend to think it will be competitive but this has yet to be proven.  As an independent national  space access system  Skylon is in a market of one and is cheap.  I can imagine that when this becomes clear its market is rather larger than the current paradigm might suggest.

The idea that a significant number of governments need or want independent LEO access is not a strong argument. It seems to have its roots in outdated ideas. Even the idea of a national airline (a far cheaper investment) is a concept that many governments as a whole are moving away from. Unless this capability is *very* affordable, or essential to defense of the national borders, it is not likely that a rush of smaller governments will place Skylon orders.

Believing that government orders for Skylon will solve the business model for REL is IMO dangerously close to wishful thinking.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 09/02/2015 12:19 am
{snip}
Or, you can buy your independent space access system with minimum of 200 launches ready developed for significantly less.

As a launch system Skylon may, or may not be cost competitive with SpaceX at al  for individual launches, I tend to think it will be competitive but this has yet to be proven.  As an independent national  space access system  Skylon is in a market of one and is cheap.  I can imagine that when this becomes clear its market is rather larger than the current paradigm might suggest.

IMHO The countries would do better to build a space port. Let multinational companies land and take off from it - for a suitable large fee (say 20% less than the US spaceports charge). European countries are overcrowded so finding land to build runways that are several miles long is very difficult. East-West runways are needed for equatorial orbits and North-South runways for polar orbits.

Countries between the Tropic of Cancer and the Tropic of Capricorn have a natural advantage for hosting a spaceport. The nearer to the Equator the runway is the heavier the cargo a Skylon can lift into orbit.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Dalhousie on 09/02/2015 12:39 am
IMHO The countries would do better to build a space port. Let multinational companies land and take off from it - for a suitable large fee (say 20% less than the US spaceports charge). European countries are overcrowded so finding land to build runways that are several miles long is very difficult. East-West runways are needed for equatorial orbits and North-South runways for polar orbits.

Runway orientations are determined by wind directions.  Are you saying that Skylon can't turn after takeoff?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: oddbodd on 09/02/2015 01:43 am
IMHO The countries would do better to build a space port. Let multinational companies land and take off from it - for a suitable large fee (say 20% less than the US spaceports charge). European countries are overcrowded so finding land to build runways that are several miles long is very difficult. East-West runways are needed for equatorial orbits and North-South runways for polar orbits.

Runway orientations are determined by wind directions.  Are you saying that Skylon can't turn after takeoff?

Nothing to do with turning ability (which Skylon obviously has to have in order to land). Everything to do with the boost of earths rotation. You're already travelling eastwards at ~1,600 km/h. If you want to take off westwards you waste fuel/payload mass taking off, turning around, and getting up to the speed you would have had if you'd simply taken off eastwards in the first place. In something as marginal as achieving orbit, that is avoided wherever possible. Polar orbits are more expensive fuel wise anyway (because you don't get the rotational assist from earth) but again, doing a U-turn is wasteful of fuel/payload mass. This is why in the case of any HTOL vehicle you really, really want a west-east oriented runway, ideally with a huge body of water to the east. It's one reason (amongst many) why Kourou in French Guiana is so attractive as a launch site.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 09/02/2015 02:12 am
Yea, and let's just ignore crap like ITAR....
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Elmar Moelzer on 09/02/2015 02:25 am
Yea, and let's just ignore crap like ITAR....
I don't see how an American law would be relevant to Skylon and its clients.
Title: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 09/02/2015 03:44 am
Depends on who builds the fuselage and what the payload is (and who built that), doesn't it?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Impaler on 09/02/2015 03:52 am

Or, you can buy your independent space access system with minimum of 200 launches ready developed for significantly less.


It is impossible to BUY independent space travel even if it came in the form of reusable vehicles because any technology this advanced requires very sophisticated maintenance and parts which makes the operator TOTALLY dependent on the manufacturer and the manufacturers government.  No nation that wants 'assured access to space' would make this kind of purchase.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 09/02/2015 04:11 am
Depends on who builds the fuselage and what the payload is (and who built that), doesn't it?

ITAR is a good reason for Reaction Engines to reject any bid from an American firm without reading it.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SteveKelsey on 09/02/2015 06:19 am

Or, you can buy your independent space access system with minimum of 200 launches ready developed for significantly less.


It is impossible to BUY independent space travel even if it came in the form of reusable vehicles because any technology this advanced requires very sophisticated maintenance and parts which makes the operator TOTALLY dependent on the manufacturer and the manufacturers government.  No nation that wants 'assured access to space' would make this kind of purchase.

Thats not correct. and this has been covered before. The principle of Skylon is to offer aircraft like operation. Any nation capable of maintaining military aircraft should be able to maintain Skylon. The liquid hydrogen supply is the most challenging issue, followed by those who can launch locally ( i.e. near equatorial) and require a reinforced runway. Both these infrastructure items can be sub-contracted to skilled suppliers.

Additionally, Skylon self ferries. Self ferrying does not require a full fuel load and can use a shorter and less demanding runway and will allow nations to access equatorial runways should they be able to secure a contract   with a launch services provider.

As a business man I could see a good market in supplying those services as all that is required is the construction of the launch  facility( which could be sub-contracted again) and the provision of launch control expertise which, on Skylon, is significantly less demanding being essentially a big, very noisy A380 size jet.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 09/02/2015 06:26 am

Depends on who builds the fuselage and what the payload is (and who built that), doesn't it?

ITAR is a good reason for Reaction Engines to reject any bid from an American firm without reading it.

May not be an American firm might be someone like the USAF.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SteveKelsey on 09/02/2015 06:32 am
...
Or, you can buy your independent space access system with minimum of 200 launches ready developed for significantly less.

As a launch system Skylon may, or may not be cost competitive with SpaceX at al  for individual launches, I tend to think it will be competitive but this has yet to be proven.  As an independent national  space access system  Skylon is in a market of one and is cheap.  I can imagine that when this becomes clear its market is rather larger than the current paradigm might suggest.

The idea that a significant number of governments need or want independent LEO access is not a strong argument. It seems to have its roots in outdated ideas. Even the idea of a national airline (a far cheaper investment) is a concept that many governments as a whole are moving away from. Unless this capability is *very* affordable, or essential to defense of the national borders, it is not likely that a rush of smaller governments will place Skylon orders.

Believing that government orders for Skylon will solve the business model for REL is IMO dangerously close to wishful thinking.

Your argument stands only if you assume no change to the current paradigm, which is hard to sustain as commercial space is about changing this paradigm. Nations that cannot access space under the current  cost structure demonstrate no wish to do so. However you cannot say this situation will remain if access becomes significantly easier from a technical perspective and cheaper economically.

Musk was right. If air travel demanded the construction of a new Boeing for every trip, no one, government or commercial operator, would bother to fly the Atlantic. The same argument applies to space access.

Government, and large corporation, appetite for space access will increase with technically simpler and economically more rewarding systems. To argue that something that is simpler and cheaper will never expand a market goes counter to the evidence for every industrial innovation I know of, from Josia Wedgwood's mastery of the mass manufacture of china to the computer chip.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 09/02/2015 07:35 am

Depends on who builds the fuselage and what the payload is (and who built that), doesn't it?

ITAR is a good reason for Reaction Engines to reject any bid from an American firm without reading it.

May not be an American firm might be someone like the USAF.

USAF can ITAR waived.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: tl6973 on 09/02/2015 09:12 am
I have been trying to work out how to understand for myself and state in simple terms why it worth bothering to split the business case into two parts: Development and construction, then operation

Unfortunately for me I am not an expert in economics, but I can see one clear benefit that might be a good reason - i just wanted to check with the knowledgeable souls here in the forum to see if I am barking up the right tree and if i have missed any other key points:

           Say, for argument's sake that your business case shows that the lifetime revenues of a fleet of Skylons can outweigh the development, construction and operations costs (this is an assumption that I'm not trying to tackle here)

If the development programme takes 10 years and the airframe lifetime is 30 years, then that is a very long time for investors to wait to recoup their initial investments.

However, if you split it down the middle, then you can have two sets of investors who will see a much quicker return on investment: those who are rewarded on investing in development through the sale of vehicles to operators, and then those who investment after the development is completed (with lower risk since Skylon has been proven to work), and start seeing a return on investment when operations begin.

So you've turned something like a 40 year investment cycle into more like two different 15-ish year cycles

You can also split your investors into two discrete expert groups: those who have experience in investing in technology (and who will also be very adept/experienced at monetising spin-off technology developments), and those who have experience in logistics, operations, fleet management, customer management etc. 

Does that make any sense? That's the principal benefit i can see of this model over building and operating it as one entity
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SteveKelsey on 09/02/2015 09:33 am
JCRM said

 "I'm not in the position to buy a launch vehicle of any description, but I doubt I would use a $1bn vehicle with a 50 hour powered flight time as a cargo vehicle, especially when anything that would fit in a Skylon would fit into a main-deck pallet space on a 747."

For clarity that was not my suggestion. I suggested self ferry to a launch site, not using Skylon as an alternative to a 747 cargo plane, which would be absurd.

 and "Much better to have your Sklyon at a spaceport, leasing the infrastructure. I'm guessing in just the same way as airlines use airports."

I agree with that.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 09/02/2015 09:42 am
I have been trying to work out how to understand for myself and state in simple terms why it worth bothering to split the business case into two parts: Development and construction, then operation


When you decide whether to buy an investment good which is available on the market, you don't really care whether the company which originally builds it has its books in order. What matters is whether your own business case as a user of the invstment good closes given the price of the good.  In "normal" space, the exact same logic applies, but the investment good is rather a one-shot investment service.
in the case of an investment good, of course, the whole economic life of the good is to be judged, so the business case is to be evaluated against market conditions.

You might argue that the conditions at which the investment good is provided to the markets depend on the conditions which close the business case for the producer: a product that, once produced, is perfectly viable, may never be built because the business case for production in first place does not close. So if the producer business case does not close, there is no business case at all for the buyer.
Of course, the buyer's business case is incorporated in the builder's business case, because if the former does not close, there will be no buyers.

Of course, the builder ex ante(1)sets a price which allows for its own business case to close, so buyer's acquisition cost reflects the builder business case. In principle, this equations are therefore codetermined.

However, REL has provided a very clear assumptions on the unitary cost and operative cost of Skylons, therefore introducing some information that constrain the builder business case. this allows for judging separately the operator case, provided Skylon works as advertised.


(1) ex post, once the upfront investment is done, the price could be pushed further down by market conditions even if the new price would not repay the initial investment. it happens very often in real economy. This will deter further investment, but not prevent production, as long as the price is high enough to grant that sales cover the company's operating expenditure (including debt servicing).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 09/02/2015 10:20 am

Thats not correct. and this has been covered before. The principle of Skylon is to offer aircraft like operation. Any nation capable of maintaining military aircraft should be able to maintain Skylon.
Military aircraft operation is heavily dependent on parts and services supply by the vendor. Ask Iran about their F 14s.
Original purchasers of foreign products usually demand either co-production to create knowledge in-country, buy huge amounts of spare parts stock for independence or have a cooperation agreements with the country of origin (like NATO) to assure access.

Independent operation only exists for very old technology aircraft that also have been produced in huge numbers so parts and knowledge are wildly available across the globe.
Title: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 09/02/2015 10:23 am
@francesco nicoli: very good explanation.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 09/02/2015 10:41 am
The idea that a significant number of governments need or want independent LEO access is not a strong argument. It seems to have its roots in outdated ideas.
Just to be clear is that your opinion we're hearing or there some actual evidence for this PoV?
Quote

Even the idea of a national airline (a far cheaper investment) is a concept that many governments as a whole are moving away from. Unless this capability is *very* affordable, or essential to defense of the national borders, it is not likely that a rush of smaller governments will place Skylon orders.

Believing that government orders for Skylon will solve the business model for REL is IMO dangerously close to wishful thinking.
REL have done market surveys to determine the potential market. While they have not stated what that breakdown is between private and government customers (although they mention that in fact there are ninety three space agencies around the world) it seems likely some of them will be nation states. That's actual evidence of a market, not an opinion.

So far only Arianespace seems to have the level of separation between mfg and launch services company to be able to integrate Skylon into it's operations.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SteveKelsey on 09/02/2015 10:53 am

Thats not correct. and this has been covered before. The principle of Skylon is to offer aircraft like operation. Any nation capable of maintaining military aircraft should be able to maintain Skylon.
Military aircraft operation is heavily dependent on parts and services supply by the vendor. Ask Iran about their F 14s.
Original purchasers of foreign products usually demand either co-production to create knowledge in-country, buy huge amounts of spare parts stock for independence or have a cooperation agreements with the country of origin (like NATO) to assure access.

Independent operation only exists for very old technology aircraft that also have been produced in huge numbers so parts and knowledge are wildly available across the globe.

Thats irrelevant.

My point was that it is easier and cheaper  for these nations to acquire  equipment and services that have been developed by a third party than to start an aerospace industry from scratch.

Did Iran have the technical depth and budget required to develop an F-14 from scratch?

Nor would Skylon suppliers and service suppliers abandon their customers. To do so would decrease their sales.

Abandoning Iran was a political decision, not a commercial one. Its not advisable to conflate the two


Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Ravenger on 09/02/2015 12:16 pm
The REL quotes I've seen about this talk about self ferry as an exceptional thing - such as after an abort. (I'm excluding the full orbital delivery/shakedown flight as being self-ferry)

I asked Alan Bond at a BIS lecture if Skylon could self-ferry, and his answer was that D1 could, but "why would you want to?" I can't remember his exact words but the implication was that towing behind a large aircraft was the preferred ferrying method, but before he could explain further he got called away.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 09/02/2015 01:22 pm
One of the things about market surveys is how you ask the question.

If you ask various nations and corporations "Would you like to own your own launch vehicle" the answer would probably be "no."

Because right now "launch vehicle" means expendable and the organization would then have to acquire the staff and skill to do their single flight.

Which is obviously stupid when they can (as people do) hand over their payload to the "Launch Services" arm of the LV mfg.

Now what happens if the question is "Would like to own a fully reusable LV with a minimum of 200 launches in it, does not drop bits of itself across the landscape and you can sell on if you no longer need it?

I think you'd get a few more "Yeses" to that question.

Full reusability makes Skylon an asset not an expense (and in effect a lottery ticket) as current ELV's are.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 09/02/2015 03:29 pm

Full reusability makes Skylon an asset not an expense (and in effect a lottery ticket) as current ELV's are.

of course it's an asset. Only a foolish would think otherwise. The question is whether it is affordable enough for a sufficient large number of countries to buy one, but the price should be really very high to put countries out of the buyers' range.

Moreover, the business case for countries buying skylons is far more stronger than for corporations. There are several reasons for it:

1) countries don't have to incorporate profits in their judgements.
2) countries have access to large budgets, money creation, or very low interest rates
3) countries may buy it for defense reasons or fast reaction capabilities.
4) countries often invest into infrastructure even if the toll they charge does not repay the expenditure, for the sake of strengthening the economy.
On this point:
Considers it as an infrastructure you provide to your economy: one billion is a very low pricetag from this point of view. And while a country, of course, makes some analyses on infrastructure use, infrastructures are often seen as preconditions for industry to emerge: they constitute the share of investment a state makes to help the economy grows. So there is little point for a country to by one Skylon if it believes that all 200 flights will be easily filled up: it should buy two!


finally, considers this.
A company with a Skylon (which exists for profits) will set the price just below the market price, which is determined by the most performer competitor (for example, spaceX). So, even if the cost of one LEO transfer is, let's say, 5 millions (as advertised by REL), the price would be just an inch below the SpaceX equivalent. the difference is the Company's profit.
A country, however, is not driven by profit. For the sake of stimulating its space and industrial sector, it could charge just the operating costs, effectively bringing the price down to 5 millions per launch in that country.
Meaning the first countries acquiring a Skylon may experience an incredible inflow of space-related investment.

Title: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 09/02/2015 03:52 pm
A country, however, is not driven by profit. For the sake of stimulating its space and industrial sector, it could charge just the operating costs, effectively bringing the price down to 5 millions per launch in that country.

No, a country could set the price at pretty much anything they want.
And of course if that really happens as much as you seem to predict it would obviously kill all that commercial Skylon market everybody is talking about because subsidized flights at half the price... well...

I still don't see it. I still believe countries are after the development of the technological knowledge if they invest because even today there's enough competition in the world market that you will always find a flight for those one or two sats a decade you really want to launch as a government.

No, if you develop your own access it's because you want to develop a domestic industry, not just make sure you get your birds launched.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 09/02/2015 04:03 pm
well, I guess that at the end it boils down once more market elasticity. But a collapse to 5 m per launch (meaning 300 euros/kg, a 50-fold decrease over current prices) could foster practically any kind of investment in any known market. There is no reason to assume that the space sector price elasticity is so much low than all the other industrial sectors in the world not to produce a shift.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 09/02/2015 04:38 pm
Well, we'll see. There was another RLV that was supposed to reach that price range....
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 09/02/2015 09:36 pm
Price elasticity in the space markets can be seen with cubesats. I suspect that soon more cubesats will have been launched than other types.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 09/03/2015 07:07 am
You are right, in fact I never tought of Cubesats as a sign of strong price elasticity, but now that you pointed at it I think that you got it right. With Skylon in place, the costs could be so low that virtually any municipality could launch a dedicated news smallsat. I think that the margins are huge, although human spaceflight will remain really costly even with Skylon, on the 300.000 eur. /ticket to LEO in the case of a public-owned vector. A dramatic decrease in respect to other plans, but still far away from mass consumption; space access remains, even with Skylons in place, a million-dollar luxury that only the richest can afford.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Impaler on 09/04/2015 06:02 am

Thats not correct. and this has been covered before. The principle of Skylon is to offer aircraft like operation. Any nation capable of maintaining military aircraft should be able to maintain Skylon.
Military aircraft operation is heavily dependent on parts and services supply by the vendor. Ask Iran about their F 14s.
Original purchasers of foreign products usually demand either co-production to create knowledge in-country, buy huge amounts of spare parts stock for independence or have a cooperation agreements with the country of origin (like NATO) to assure access.

Independent operation only exists for very old technology aircraft that also have been produced in huge numbers so parts and knowledge are wildly available across the globe.

Thats irrelevant.

My point was that it is easier and cheaper  for these nations to acquire  equipment and services that have been developed by a third party than to start an aerospace industry from scratch.

Did Iran have the technical depth and budget required to develop an F-14 from scratch?

Nor would Skylon suppliers and service suppliers abandon their customers. To do so would decrease their sales.

Abandoning Iran was a political decision, not a commercial one. Its not advisable to conflate the two

Countries create their own 'independent' access to space exactly because of fear of being cut off for POLITICAL reasons, no one has any doubt that commercial launch operators on the international market will always be available at a market price. 

I can guaranteed you that Skylon manufacturers will be barred from selling to governments that the UK deems hostile, and the supply of parts would be subject to being pulled the moment relations turn sour, the more nations are involved in building it the more would have a veto on who can buy it, it would be as closely guarded as ICBM technology because Skylon is a fairly obvious substitute for an ICBM.

Space access is highly politically charged due to the extreme military importance of space assets and the national prestige attached to having access.  It is not like selling an AirBus to Indonesia.

Skylon is so cutting edge that only the worlds most advanced airo-space companies have a prayer or even being able to build it IF it can even be built, it makes most military air-craft look like balsa-wood gliders by comparison.  No hypothetical buyer nation outside the G7 could maintain such a vehicle on it's own, they would all be dependent on a constant stream of parts and skilled labor from the manufacturer so much so that it would be a de-facto lease.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SteveKelsey on 09/04/2015 07:44 am
 Please excuse me if I bin the quotation string at this point, its becoming too long for legibility


Skylon is intended to be precisely like selling an Airbus to Indonesia, that is Reaction Engines stated design intent,an SSTO with aircraft like operations.

You are also referencing construction which is irrelevant. non-G7 nations don’t have to build Skylon, they only need to buy it and run it. If they can buy and run military aircraft they can buy and run Skylon.

The political restraints you raise apply to any G7 military manufacturer The Skylon purchase market is restricted by these conventions to the same markets as served by Lockheed Martin,Boeing,BAE,Northrop Grumman,General Dynamics,EADS, to name a few. These markets have both the appetite and the ability to purchase advanced aircraft. They may not have the ability to design and develop their own space access system-thats the point. Skyline is a shrink wrapped space program and seen this way it looks cheap. Any customer nation of the defence contractors noted would be capable of buying and running Skylon.

A second market exists that would be able to lease time on Skylon. These customers need a payload and a cheque book- note the discussion on cubsats above.

As to the difficulty of building Skylon in the first place I will leave others to comment if they wish to. Personally from what I have read I think you may be overstating the case. Its simpler than the Shuttle and the Shuttles were built decades ago. Materials have improved since then, design tools have developed substantially since then, manufacture and assembly of components made from exotic materials has broadened since then, and the major components will be built in technically advanced G7 nations.

Finally, as has been commented on many times, Skylon makes a terrible ballistic missile. Its launch profile is leisurely in comparison to an ICBM, its a very fluffy design and so its re-entry is slow  and its final approach is even slower,and it provides a very large heat signature for the bulk of its decent.  Although I have never purchased an ICBM, I also suspect from the construction differences between say a Polaris and Skylon, Skylon would be extravagantly expensive as a ballistic missile substitute. This is where Skylon would be at a severe market disadvantage.

I think we are straying into repetition at this point.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 09/04/2015 03:54 pm
It's worth repeating what others have said before: while Skylon would indeed be a launcher you could buy 'off the shelf' it's continued value would be dependent upon it being inspected, serviced, and having parts replaced. Whoever provides those services (presumably REL or a spinoff) could hold everyone's space program to ransom.

Or you could attempt to service it yourself and make spare parts, but my guess is establishing and maintaining that capability is cost prohibitive.

Note: I'm not saying that Skylon won't meet their reliability and reusability goals, but no-one should have the impression you could just buy one with cash and then expect to just pump in H2 and LOX and then sell it after 200 flights. The analogy with 4th/5th generation fighter aircraft is probably about right.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SteveKelsey on 09/04/2015 04:11 pm
And any defence supplier could do the same with precisely the same result, the loss of their customer base . Who would buy from them in the future.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 09/04/2015 04:21 pm
And any defence supplier could do the same with precisely the same result, the loss of their customer base . Who would buy from them in the future.

I agree 100%. The difference is Airbus/Boeing/Lockheed-Martin are massive companies with long-term government contracts/subsidies so you can guarantee they'll be around for a few years and will want to keep their customers happy. REL on the other hand could fold comparatively quickly, and would not be bailed out if the financials didn't look compelling.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 09/04/2015 04:59 pm
How about this bit of fiction:

+ In 2018 progress on the SABRE test-bed has been sufficiently encouraging to draw more investors.
+ The UK government signs a multi-billion pound contract with a REL company to provide launch services for UK satellites for the years x to y. This represents a saving of £z over projected launch costs for those years when you factor in the overall value to the UK economy.
+ The launch contract is structured principally on fee per launch, so technical problems and financing difficulties would not cost the taxpayer, but could theoretically derail the program. However, the UK gov has a vested interest in the venture succeeding so would help smooth out issues.
+ With that backing and stability in place, other investors join the program, enabling its development.

And finally, because of the above...
+ Indonesia (to use SteveKelsey's example) buys a Skylon, confident the program will continue, along with servicing contracts.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SteveKelsey on 09/04/2015 05:07 pm
And any defence supplier could do the same with precisely the same result, the loss of their customer base . Who would buy from them in the future.

I agree 100%. The difference is Airbus/Boeing/Lockheed-Martin are massive companies with long-term government contracts/subsidies so you can guarantee they'll be around for a few years and will want to keep their customers happy. REL on the other hand could fold comparatively quickly, and would not be bailed out if the financials didn't look compelling.

You are going to have to unpack your logic for me. Large or small if you want to keep in business you keep your customers happy. You and others have proposed the potential for REL to hold customers to ransom. REL have never suggested this, not would they unless they wanted to destroy their credibility from the get go.

 My point was that no contractor of any scale or designation could afford to do this as they would never be trusted and no one would buy from them.

I don't see how this illogical hypothetical could be linked to any projection of Skylon's success.

Purely as an aside, and not part of the Skyline debate, the only supplier who might be tempted to play fast and loose with their customers on meeting expected ( and presumably contracted)  support services would be a monopoly supplier, not a start-up.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SteveKelsey on 09/04/2015 05:09 pm
How about this bit of fiction:

+ In 2018 progress on the SABRE test-bed has been sufficiently encouraging to draw more investors.
+ The UK government signs a multi-billion pound contract with a REL company to provide launch services for UK satellites for the years x to y. This represents a saving of £z over projected launch costs for those years when you factor in the overall value to the UK economy.
+ The launch contract is structured principally on fee per launch, so technical problems and financing difficulties would not cost the taxpayer, but could theoretically derail the program. However, the UK gov has a vested interest in the venture succeeding so would help smooth out issues.
+ With that backing and stability in place, other investors join the program, enabling its development.

And finally, because of the above...
+ Indonesia (to use SteveKelsey's example) buys a Skylon, confident the program will continue, along with servicing contracts.

Please don't link me to your fantasy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: tl6973 on 09/04/2015 05:13 pm
REL have repeatedly stated that they are not interested in building Skylon.

They want to be the engine manufacturer and have said that Skylon would most likely be built by a consortium of established and experienced (I.e. Credible) airframers.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 09/04/2015 05:28 pm
How about this bit of fiction:

+ In 2018 progress on the SABRE test-bed has been sufficiently encouraging to draw more investors.
+ The UK government signs a multi-billion pound contract with a REL company to provide launch services for UK satellites for the years x to y. This represents a saving of £z over projected launch costs for those years when you factor in the overall value to the UK economy.
+ The launch contract is structured principally on fee per launch, so technical problems and financing difficulties would not cost the taxpayer, but could theoretically derail the program. However, the UK gov has a vested interest in the venture succeeding so would help smooth out issues.
+ With that backing and stability in place, other investors join the program, enabling its development.

And finally, because of the above...
+ Indonesia (to use SteveKelsey's example) buys a Skylon, confident the program will continue, along with servicing contracts.

Please don't link me to your fantasy

I was trying to build up a scenario that made your claim (Indonesia buys Skylon with confidence) more credible.

And on the word 'ransom': I didn't mean to imply REL (or another company) would actually hold owners to ransom, merely that a purchaser would know that are dependent upon someone else for servicing. And if the servicer is a small company without major contracts or government support, there's a risk they could go bankrupt.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RonM on 09/04/2015 05:29 pm
REL have repeatedly stated that they are not interested in building Skylon.

They want to be the engine manufacturer and have said that Skylon would most likely be built by a consortium of established and experienced (I.e. Credible) airframers.

Yes. They would probably go with one of the usual suspects for aircraft: Airbus, Boeing, or Lockheed Martin.

Either Boeing or Lockheed Martin would be good because of space experience. Airbus would be good because its European, but it would probably have to work with Arianespace for space experience.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SteveKelsey on 09/04/2015 05:37 pm
How about this bit of fiction:

+ In 2018 progress on the SABRE test-bed has been sufficiently encouraging to draw more investors.
+ The UK government signs a multi-billion pound contract with a REL company to provide launch services for UK satellites for the years x to y. This represents a saving of £z over projected launch costs for those years when you factor in the overall value to the UK economy.
+ The launch contract is structured principally on fee per launch, so technical problems and financing difficulties would not cost the taxpayer, but could theoretically derail the program. However, the UK gov has a vested interest in the venture succeeding so would help smooth out issues.
+ With that backing and stability in place, other investors join the program, enabling its development.

And finally, because of the above...
+ Indonesia (to use SteveKelsey's example) buys a Skylon, confident the program will continue, along with servicing contracts.

Please don't link me to your fantasy

I was trying to build up a scenario that made your claim (Indonesia buys Skylon with confidence) more credible.

And on the word 'ransom': I didn't mean to imply REL (or another company) would actually hold owners to ransom, merely that a purchaser would know that are dependent upon someone else for servicing. And if the servicer is a small company without major contracts or government support, there's a risk they could go bankrupt.

Understood and thank you for the clarification. I mistook your intent so i apologise if I caused offence.

 I would like to point out it wasn't my claim, i was responding to an earlier post.

 REL's stated objective is an SSTO with aircraft like operation, which another poster was bringing into question.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 09/04/2015 05:40 pm
Details aside, my point is a simple one: once a Skylon is sold, it's continued value is dependent on someone maintaining the airframe (e.g. Airbus), and/or the engine provider servicing the SABREs (i.e. REL or a sub).

If these servicing companies could go out of business, that's a risk that must be factored in. Once REL has major contracts, you can have confidence they'll be around to maintain your SABREs.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 09/04/2015 06:40 pm
REL have repeatedly stated that they are not interested in building Skylon.

They want to be the engine manufacturer and have said that Skylon would most likely be built by a consortium of established and experienced (I.e. Credible) airframers.

Can anyone seriously imagine them in 2020s, having built workable, flyable Sabre that have hundreds of ground tests and just saying whole damn we can't get consortium together to build the airframe let abandon the whole idea.

Nope me either, if they can't build such a consortium and I'm personally of the opinion they don't have a hell in chance of building one, they will proceed to do it themselves, just like they have done everything else themselves to date.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 09/04/2015 07:19 pm
Knowles2
**Can anyone seriously imagine them in 2020s, having built workable, flyable Sabre that have hundreds of ground tests and just saying whole damn we can't get consortium together to build the airframe let abandon the whole idea.**

If, as you suggest, REL managed to produce a successful SABRE engine but couldn't convince Boeing or Airbus or whoever to come on-board and build an airframe, they might well give up on Skylon as envisioned now. I say this because REL would know that investors would be very reluctant to pour $Bns into a project which was being overseen by people with little, or at best less experience than Boeing et al in that area. REL might therefore decide to use the SABRE technology in another area of aerospace instead of Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 09/04/2015 08:36 pm

of course it's an asset. Only a foolish would think otherwise.
To an Accountant or an Economist it's obvious. But this is radically different from all current systems, where the ELV is a ticket to ride.

No, a country could set the price at pretty much anything they want.
And of course if that really happens as much as you seem to predict it would obviously kill all that commercial Skylon market everybody is talking about because subsidized flights at half the price... well...
Except a 1st generation Skylon has a 200 (full trajectory ) flight design life. At which point they will proved the system works very well indeed and have a scrap Skylon. However it is REL's plan that early adoptors would not be alone for long.
Quote
I still don't see it. I still believe countries are after the development of the technological knowledge if they invest because even today there's enough competition in the world market that you will always find a flight for those one or two sats a decade you really want to launch as a government.
But that's the point. In truth the whole global market could be serviced (probably) by 2 ELVs, A big one like Atlas V and a smaller one like Soyuz If all countries agreed to pool their launches.

But they don't.

Imagine being a US researched developing a probe with any USG funding and trying to get it launched on a non US launcher.

There are also serious ICBM proliferation issues with ELV technology

But even if you develop your own in country LV what exactly do you have?

A very complex artifact that's used once and thrown away, and the ongoing standing army to build and launch more.  :(
Quote
No, if you develop your own access it's because you want to develop a domestic industry, not just make sure you get your birds launched.
Are you aware that the UK has a substantial "domestic" space industry IE multi £Bn turnover, 10s of 1000s of jobs with no launch vehicle of it's own?

All of that hardware has launched on other people's LV's (including the Shuttle).

That's a position quite a lot of countries share but a large part of that is that having "your" own ELV gives you very little lasting benefit. It's expensive to develop, expensive to operate (probably low flight rate and high standing army, including a gunnery range to launch over) and you have to keep the factory ticking over because once you've launched it, it's gone.

Unless you already have developed an ELV the question is why bother?
 
This is part of why Skylon is a step change in how space could be done.  You have a lasting asset that launches on your schedule (instead of like scheduling a plumber in the USSR in the Cold War, "4 years from next Friday."  :) ) and depending on your location may be able to deliver a payload to orbit entirely from the host countries territory.

Well, we'll see. There was another RLV that was supposed to reach that price range....
And your point....

The root causes for the failure of the Shuttle to deliver its objectives have been discussed at considerable length.

If REL could only secure the funding profile of STS (with it's ridiculous yearly constraints) I think they'd just walk away in disgust.  :(
You are right, in fact I never tought of Cubesats as a sign of strong price elasticity, but now that you pointed at it I think that you got it right. With Skylon in place, the costs could be so low that virtually any municipality could launch a dedicated news smallsat. I think that the margins are huge, although human spaceflight will remain really costly even with Skylon, on the 300.000 eur. /ticket to LEO in the case of a public-owned vector. A dramatic decrease in respect to other plans, but still far away from mass consumption; space access remains, even with Skylons in place, a million-dollar luxury that only the richest can afford.
Actually that would put it slightly above the asking price for a Virgin Galactic sub orbital flight, which it should be given the substantially higher energy costs.

Keep in mind the last advertised price for a tourist to the ISS was $20m (although I think most have claimed the price paid was lower).

That would be roughly a 100x price reduction.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 09/04/2015 08:47 pm
Countries create their own 'independent' access to space exactly because of fear of being cut off for POLITICAL reasons, no one has any doubt that commercial launch operators on the international market will always be available at a market price. 
But on the flip side countries will not releases launches to the international market for fear of having that access cut off or their indigenous supplier go out out of business.

Hence the $1Bn year "assured access" payment to ULA, maintaining the revenue of ULA to an acceptable level (for their joint owners, not the US taxpayer  :( ).

BTW you need seem to be having continuing trouble with quoting. It makes reading your comments difficult. If you want to quote use the "quote" button on the right hand side of the screen. Do not cut and paste.

Quote
I can guaranteed you that Skylon manufacturers will be barred from selling to governments that the UK deems hostile, and the supply of parts would be subject to being pulled the moment relations turn sour, the more nations are involved in building it the more would have a veto on who can buy it,
Now that is likely.

A very good reason to keep US involvement at arms length.
Quote
it would be as closely guarded as ICBM technology because Skylon is a fairly obvious substitute for an ICBM.
This topic has been discussed with posters from Israel.

It's a plot for a cheap straight-to-download thriller.

IRL if you've got the funding, the skills and the motivation to "weaponize" a Skylon you'd already have ways to create mass mayhem far more cheaply and with as great an impact.

I won't comment on what those might be as it would only make the irrationally paranoid more paranoid and set the weaker minded to considering ways and means.  :(
Quote
Space access is highly politically charged due to the extreme military importance of space assets and the national prestige attached to having access.  It is not like selling an AirBus to Indonesia.

Skylon is so cutting edge that only the worlds most advanced airo-space companies have a prayer or even being able to build it IF it can even be built, it makes most military air-craft look like balsa-wood gliders by comparison.  No hypothetical buyer nation outside the G7 could maintain such a vehicle on it's own, they would all be dependent on a constant stream of parts and skilled labor from the manufacturer so much so that it would be a de-facto lease.
And yet some how China, India and (IIRC) Indonesia do maintain large fleets of large aircraft.

On a serious note Skylon is big but it's also relatively simple, as its skin is separate (and separable) from it's framework. Likewise it's tanks are designed to "float" inside the body. Again (in principle) those could be extracted and certainly externally inspected (but it's a major overhaul, not a routine task) and of course the wing tip engine pods are much more accessible than those of say the SR71.

Having no provision for humans (unless someone installs a passenger module in the payload bay) keeps things a lot simpler in terms of services like galleys, toilets and aircon.

Skylons skins is designed to be riveted to the frame and in sections, because that's been how aircraft have been patched in the past. So provided the parts, training and diagnostics (and I expect on board health monitoring will be a big part of Skylon) I think most nations could find enough smart people to maintain one.


Yes. They would probably go with one of the usual suspects for aircraft: Airbus, Boeing, or Lockheed Martin.
True. Of course on the flip side no company has experience with these materials, so it's more the peripheral issues, around big vehicle design and procurement, and certification.
Quote
Either Boeing or Lockheed Martin would be good because of space experience.
LM is  a pure government contractor and most of that is for various kinds of weapons.

That is a very poor fit for a commercially funded project that has a time to market measured in years, not decades.  :(
Quote
Airbus would be good because its European, but it would probably have to work with Arianespace for space experience.
Airbus mfg Ariane 5. Arianspace sells launches of Ariane 5.

Arianespaces experience is in payload sales and marketing.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 09/06/2015 04:21 am
BAE SYSTEMS is a British based an aircraft manufacturer. If the UK Government is paying it may be happy to build a SSTO spacecraft.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 09/06/2015 07:37 pm
Knowles2
**Can anyone seriously imagine them in 2020s, having built workable, flyable Sabre that have hundreds of ground tests and just saying whole damn we can't get consortium together to build the airframe let abandon the whole idea.**

If, as you suggest, REL managed to produce a successful SABRE engine but couldn't convince Boeing or Airbus or whoever to come on-board and build an airframe, they might well give up on Skylon as envisioned now. I say this because REL would know that investors would be very reluctant to pour $Bns into a project which was being overseen by people with little, or at best less experience than Boeing et al in that area. REL might therefore decide to use the SABRE technology in another area of aerospace instead of Skylon.

An yet they have pure in billions into Space X.

I don't think there many other areas REL could be applied to. REL would be reduce to a glorified patent licence company and I don't think they would be happy with.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 09/06/2015 10:14 pm
BAE SYSTEMS is a British based an aircraft manufacturer. If the UK Government is paying it may be happy to build a SSTO spacecraft.
Do they even still have any capability to make large aircraft though? They sold their stake in Airbus ten years ago, do they have any facilities or experience left to enable them to be the prime airframer for Skylon?
Their Taranis UAV work is probably useful software wise but beyond that what do they have to offer?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Dalhousie on 09/06/2015 10:33 pm
BAE SYSTEMS is a British based an aircraft manufacturer. If the UK Government is paying it may be happy to build a SSTO spacecraft.
Do they even still have any capability to make large aircraft though? They sold their stake in Airbus ten years ago, do they have any facilities or experience left to enable them to be the prime airframer for Skylon?
Their Taranis UAV work is probably useful software wise but beyond that what do they have to offer?

They are supposedly still making wings for the A320, A330, and A340, large components for the B777, as well projects on a number of smaller aircraft - Hawk, F-35, Typhoon, Grippen, and ongoing BAe 125 manufacture.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 09/06/2015 11:04 pm
BAE SYSTEMS is a British based an aircraft manufacturer. If the UK Government is paying it may be happy to build a SSTO spacecraft.
Do they even still have any capability to make large aircraft though? They sold their stake in Airbus ten years ago, do they have any facilities or experience left to enable them to be the prime airframer for Skylon?
Their Taranis UAV work is probably useful software wise but beyond that what do they have to offer?

They are supposedly still making wings for the A320, A330, and A340, large components for the B777, as well projects on a number of smaller aircraft - Hawk, F-35, Typhoon, Grippen, and ongoing BAe 125 manufacture.
Aren't the wings for those aircraft made being made by Airbus UK at Airbus Broughton and isn't the Bae 125 a) out of production and b) not been made by BAE since 1993 when the division was sold to Raytheon.
How much cross over in capabilities is there between making jet fighters and an aircraft the size of an A380 but constructed like an airship?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Dalhousie on 09/07/2015 01:43 am
BAE SYSTEMS is a British based an aircraft manufacturer. If the UK Government is paying it may be happy to build a SSTO spacecraft.
Do they even still have any capability to make large aircraft though? They sold their stake in Airbus ten years ago, do they have any facilities or experience left to enable them to be the prime airframer for Skylon?
Their Taranis UAV work is probably useful software wise but beyond that what do they have to offer?

They are supposedly still making wings for the A320, A330, and A340, large components for the B777, as well projects on a number of smaller aircraft - Hawk, F-35, Typhoon, Grippen, and ongoing BAe 125 manufacture.
Aren't the wings for those aircraft made being made by Airbus UK at Airbus Broughton and isn't the Bae 125 a) out of production and b) not been made by BAE since 1993 when the division was sold to Raytheon.
How much cross over in capabilities is there between making jet fighters and an aircraft the size of an A380 but constructed like an airship?

I am only relying on what I can find on Google. :)

The answer to your last question can oly be "limited", but that would be true of everyone.  What BAe does have is experience with large aerospace projects generally, plus working with advanced materials and aerospace construction programs.

As you say Airbus UK would be another UK contender.

'You're right about the 125.
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 09/07/2015 08:09 am
BAE SYSTEMS is a British based an aircraft manufacturer. If the UK Government is paying it may be happy to build a SSTO spacecraft.
Do they even still have any capability to make large aircraft though? They sold their stake in Airbus ten years ago, do they have any facilities or experience left to enable them to be the prime airframer for Skylon?
Their Taranis UAV work is probably useful software wise but beyond that what do they have to offer?

I should hope they do as they are going to be one of the primes on the UK's sixth generation combat aircraft/drone. Or did you miss the point of Taranis which is not just some software exercise as you seem to be characterising it but actually a way to build & test sixth generation technologies. Being as Taranis is fairly classified project I'm not sure how you expect to find out much beyond what's in the press releases online.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 09/07/2015 09:27 am
BAE SYSTEMS is a British based an aircraft manufacturer. If the UK Government is paying it may be happy to build a SSTO spacecraft.
Do they even still have any capability to make large aircraft though? They sold their stake in Airbus ten years ago, do they have any facilities or experience left to enable them to be the prime airframer for Skylon?
Their Taranis UAV work is probably useful software wise but beyond that what do they have to offer?

I should hope they do as they are going to be one of the primes on the UK's sixth generation combat aircraft/drone. Or did you miss the point of Taranis which is not just some software exercise as you seem to be characterising it but actually a way to build & test sixth generation technologies. Being as Taranis is fairly classified project I'm not sure how you expect to find out much beyond what's in the press releases online.
I said the software experience was useful because Taranis is an autonomous drone and that seemed relevant to building an SSTO drone, but construction wise they're obviously vastly different aircraft and an ability to be prime on a fighter jet from scratch (something they haven't really done in decades)  is presumably a very different challenge than building super large airliners which would seem likely to contain more relevant experience because even if they're being constructed in a radically different manner they have similar construction needs, i.e. very large construction halls, transport of outsized parts etc.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: tl6973 on 09/07/2015 12:09 pm
Some other European candidates for air-frame construction:

Dassault Aviation

Quote
Wikipedia
In 2015, Dassault Aviation is a multinational company employing almost 11,745 people, including 9,000 in France, with a commercial presence in over 83 countries and its activities are centered on the following areas:

>aeronautics with 8,000 aircraft delivered since 1945, mainly business jets representing 71% of activity (Falcon)   and also military aircraft (Mirage 2000, Rafale and nEUROn),

>space activities (ground telemetry systems, spacecraft design and pyrotechnic activities),

>services (Dassault Procurement Services, Dassault Falcon Jet and Dassault Falcon Service),

>aerospace and defense systems (Sogitec Industries).

Finmeccannica

Quote
Wikipedia
Finmeccanica S.p.A. is the leading industrial group in the high-technology sector in Italy and one of the main global players in aerospace, defence and security. It operates in seven sectors: aeronautics, helicopters, space, electronics, defence systems, transportation and construction.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 09/07/2015 03:26 pm
If we're playing fantasy consortium building then the likely culprits are probably:

GKN to make all the composite spars.

Airbus UK to make the wings.

Airbus Defence and Space to make the tanks, SOMA engine.

Finmeccannica to make the passenger module.

Thales Alenia to make the upper stage.

BAE to make the nacelles.

Construction location is probably dependant on politics, it needs a runway and permission for takeoff unless the site is capably of sending a Skylon out by water. The UK government will want it constructed in the UK which makes the most likely sites either Newquay if it gets the spaceport or Warton if it doesn't.  Either way a new facility would probably be need at which ever site.
The major components left, payload bay, undercarriage, etc would probably be split up by work share and the consortium will end up looking like the eurofighter  BAE/Airbus/Finmeccannica.

Anyway that's pretty much how I see things coming together should things manage to come together.
I personally think the risk of a consortium failing to come together is higher than the risk of the SABRE prototype engine not being completed before 2020 but I also think that the political will behind Skylon both in the UK and Europe
shouldn't be underestimated, much of UK space policy is being made with Skylon in mind and ESA has spent the last decade carefully helping the project along. Should REL succeed in building the engine as promised and the European Aerospace industry declines to put it in a vehicle then I think a lot of political goodwill will be lost.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 09/08/2015 10:06 am
did Chris in the new article just revealed that SpaceX suspended the first stage recovery agenda until they finish explore potential full reusability, or I am getting it wrong?

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: tl6973 on 09/08/2015 10:49 am
It's referring to the second stage:

Quote
The review focused on changes to the Second Stage (L2), such as the reduction in weight and margins since SpaceX opted against recovery attempts of this stage in its current configuration.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 09/08/2015 04:11 pm
BAE SYSTEMS is a British based an aircraft manufacturer. If the UK Government is paying it may be happy to build a SSTO spacecraft.
Do they even still have any capability to make large aircraft though? They sold their stake in Airbus ten years ago, do they have any facilities or experience left to enable them to be the prime airframer for Skylon?
Their Taranis UAV work is probably useful software wise but beyond that what do they have to offer?
Given the materials use in Skylon and given the size of the craft I doubt any company has a ready made facility in the UK or in fact anywhere in the world. A big sum would have to be invested building such a facility capable of manufacturing the plane.  Plus the Runway requirement means you may as well build a new facility and runaway rather doing what I presume would be a costly upgrade of existing runway and delay delivery of planes to existing customers.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 09/08/2015 11:59 pm
Given the materials use in Skylon and given the size of the craft I doubt any company has a ready made facility in the UK or in fact anywhere in the world. A big sum would have to be invested building such a facility capable of manufacturing the plane.
Depends. The vehicle is nowhere near the height of a high bay, maybe 60 feet total. Most of the structures will be fairly lightweight. Things get trickier as near full assembly and very large once you add the wings.  A lot would depend on what sort of production rate you're looking for.

As for runway weight that depends. On air breathing only to a test site the vehicle is 150 tonnes lighter, considerably shortening and lightening the runway needed.
Quote
Plus the Runway requirement means you may as well build a new facility and runaway rather doing what I presume would be a costly upgrade of existing runway and delay delivery of planes to existing customers.
There are basically 3 options. Sub orbital testing, orbital with no payload and fully loaded to orbit.

I think you could get away with a lot of testing from an A380 or 777 certified runway.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 09/11/2015 03:45 pm
Wonder if this increases the likelihood of RR considering some kind of merger or takeover down the line.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 09/12/2015 12:37 pm
Another interesting hire:
Quote from: http://www.reactionengines.co.uk/news_updates.html
Jonathan Hale joins the Reaction Engines Ltd Board as a Non-Executive Director
[...]
Jonathan has over 35 years of commercial and financial experience in the aerospace, energy, mining and consulting sectors. Prior to joining C-FEC, a revolutionary wind turbine company, Jonathan was Director of Corporate Strategy for Rolls Royce plc and a member of its Group Executive, retiring in 2010. He was responsible for corporate strategy, M&A, development of new businesses and partnerships, and commercialisation of technology.
[...]
Jonathan has an MBA from Harvard School of Business Administration and an MA and BA from Cambridge University in Metallurgy and Materials Science.

Sorry, no permalink.
More Rolls Royce staff, perhaps pointing towards an engine partner, or perhaps the work RR did on the predecessor gives them more confidence to join REL.


Quote
Jonathan Hale, the former Strategy Director at Rolls-Royce, understands how to shape company strategy better than pretty much anyone you could wish to meet. - Jonathan Mitchell former Global CIO of Rolls-Royce

I think what this continues to show is that serious people are taking REL seriously. Perhaps it's time for Skylon graduate from advanced concepts.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 09/12/2015 05:39 pm
I think what this continues to show is that serious people are taking REL seriously. Perhaps it's time for Skylon graduate from advanced concepts.
It's a fair question. I'd like to see a few more companies other than RR show themselves

What bothers me is they don't seem to have anyone with a serious background in raising money.

The next steps are big upgrades in cash, but (I would guess) much lower levels of risk that an "unknown unknown" will turn up and make it unworkable.

This would seem to be the point at which they need to get someone who can talk to the right kind of investor.

If you can handle the level of risk involved REL has a very good story to tell about its use of investors money and its ability to deliver what it promises when it promises to do so.

Those are significant virtues for investors, some of which simply won't look at less than $Bn investments due to their size.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 09/12/2015 06:57 pm
I think what this continues to show is that serious people are taking REL seriously. Perhaps it's time for Skylon graduate from advanced concepts.
It's a fair question. I'd like to see a few more companies other than RR show themselves

What bothers me is they don't seem to have anyone with a serious background in raising money.

The next steps are big upgrades in cash, but (I would guess) much lower levels of risk that an "unknown unknown" will turn up and make it unworkable.

This would seem to be the point at which they need to get someone who can talk to the right kind of investor.

If you can handle the level of risk involved REL has a very good story to tell about its use of investors money and its ability to deliver what it promises when it promises to do so.

Those are significant virtues for investors, some of which simply won't look at less than $Bn investments due to their size.


If you look here:

https://www.linkedin.com/company/reaction-engines-limited

You can find a slightly more extensive list of employees and there are a couple maybe fits that profile, such as Allister Furey who's currently a Consultant at Reaction Engines but has seemed to have spent ten years sitting on either side of the VC table.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 09/15/2015 12:37 pm
For anyone able to attend there's a lecture coming up Wednesday, 11 November presented by Dr. Robin Davies, Control Systems Engineer, Reaction Engines Ltd.
It's being held at  The Airbus Conference Suite, Airbus UK, Chester Road, Broughton, CH4 0DR.

So at least we can be sure Airbus have heard of Skylon.

http://aerosociety.com/Events/Event-List/2172/The-Skylon-Spaceplane-and-Sabre-Engine-Progress-to-Date-and-Future-Prospects
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 09/16/2015 11:23 pm
not exactly skylon news but....

A Lapcat II design was proposed yesterday by REL-affiliated ESA researches, a mach-8 airliner apparently.

http://www.bbc.com/future/story/20150914-the-challenges-of-building-a-hypersonic-airliner
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 09/17/2015 04:02 am
In the BBC article they refer to a 'thermal paradox' where heating is less severe for a Mach 8 vehicle than a Mach 5 one. Below is the article that explains that (essentially overall heating is more manageable for a Mach 8 vehicle because the flight time - at high temperatures - is reduced since you land earlier.)

http://www.congrexprojects.com/Custom/15A01/Papers/Room%202.1/Thursday/Long%20range%20transatmospheric%20systems%20II/90155_Steelant.pdf

I guess this is a strike against the Mach 5 REL LAPCAT A2 concept.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 09/17/2015 07:59 am
not exactly skylon news but....

A Lapcat II design was proposed yesterday by REL-affiliated ESA researches, a mach-8 airliner apparently.

http://www.bbc.com/future/story/20150914-the-challenges-of-building-a-hypersonic-airliner
Closer than you might realize.

LAPCAT started with something like 6-8 proposals up to M8.

Only 2 survived. The M5 H2 fueled pre cooled turbo ramjet and the M8 Keroscene SCRamjet.
The M5 design came from Reaction engines, the SCRamjet from DLR but only the M5 design had the range to spend most of the flight at M5 and still have enough fuel left over for a subsonic flight to the target airports.

Clicking on the "AIAA Hypersonic Plane" link in the article gave the 1st page of the report and in the abstract it mentions part of the preparatory work for this was a cross checking of high velocity wind tunnels across Europe, so results from one can be matched (at a different speed) to results from another.

It is handy to know such things should you find yourself wanting to build a vehicle with a very broad Mach range.

And now REL have that information.
In the BBC article they refer to a 'thermal paradox' where heating is less severe for a Mach 8 vehicle than a Mach 5 one. Below is the article that explains that (essentially overall heating is more manageable for a Mach 8 vehicle because the flight time - at high temperatures - is reduced since you land earlier.)

http://www.congrexprojects.com/Custom/15A01/Papers/Room%202.1/Thursday/Long%20range%20transatmospheric%20systems%20II/90155_Steelant.pdf

I guess this is a strike against the Mach 5 REL LAPCAT A2 concept.
Dig a little deeper.

Those models are very crude.  :( . their structural model for the vehicle seems quite crude as well. A superalloy skin with borosilicate glass fibre insulation. I would have guessed Titanium would be more likely today. Internally PU foam is good enough to stop water vapour freezing around an LH2 tank and modern foams have reuse temperatures of 250c.  They are also running comparisons with  the SHEFEX II flight experiment using flat panels of RCC.

While that sort of makes sense, since the vehicle is modeled as a set of inclined plates, it's still not clear if the RCC had an anti oxidation coating, which probably would not have been needed for a sounding rocket flight but which would be absolutely essential to stop it burning off.

Enthusiasts for RCC tend to gloss over the small detail that the coating sets the real limits on RCC's emissivity, fatigue life and oxidation resistance.  :(

Actually the report's conclusions would not be too surprising to people who've studied re-entry heating.

Capsules have intense peak heating but for a very short time, giving a shortish integrated heat pulse, while the Shuttle had lower overall temperatures but for a prolonged period, resulting in a larger total heat load.

Due to the fixed distance in this situation higher Mach translates to shorter time, higher peak pulse.

I think the sentence "Overall this paradox is challenging but demands extreme care" should have also been in the conclusion (it's in the paragraph before).

TBH given the numbers listed it looks like the Skylon structure of Titanium space frame covered by a longitudinally corrugated SiC reinforced borosilicate glass is looking quite promising for this application as well.

Keep in mind that this theoretical advantage only happens if you can get to M8. No one is anywhere near close to building an aircraft sized SCRamjet (the "SR72" is a set of power points and if built will still be a drone, not a crew carrier), let alone a 300 passenger aircraft.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 09/17/2015 10:06 am
guys, I think I need few clarifications as I am no engineer.

Is this lapcat II design a hybrid jet-rocket engine like Skylon?

If not, what are the implications for future Skylon design, provided that Skylon D1 is expected to travel up to M5 before switching in rocket mode, and this lapcat II design is expected to reach M8 wthout rocket mode (if I understand it well)?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 09/17/2015 08:01 pm
guys, I think I need few clarifications as I am no engineer.

Is this lapcat II design a hybrid jet-rocket engine like Skylon?

If not, what are the implications for future Skylon design, provided that Skylon D1 is expected to travel up to M5 before switching in rocket mode, and this lapcat II design is expected to reach M8 wthout rocket mode (if I understand it well)?
The focus is the DLR "MR2" design, which is their M8 plan.

http://www.icas.org/ICAS_ARCHIVE/ICAS2014/data/papers/2014_0428_paper.pdf

This vehicle is LH2 fueled. It seems to run in 3 stages. An Air Turbo Rock is meant to generate thrust and initial air motion up to ramjet ignition then that cuts over eventually to a SCRamjet at the full M8 cruise speed.

Combustion and  inlet studies are a big part of this programme.

Like all SCRamjets it promises huge benefits. Also like all SCRamjets every part of it is intimately linked to every other part from the inlets backwards. Which means any slight change has to be worked through the whole design.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 09/23/2015 10:33 am
I wonder what this is all about?

http://aviationweek.com/technology/turbine-engine-could-pave-way-supersonic-cruise-missiles
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 09/23/2015 12:03 pm
I wonder what this is all about?

http://aviationweek.com/technology/turbine-engine-could-pave-way-supersonic-cruise-missiles
About 55 years too late.

The J58 on the SR71 maanged that in the early 60's.

However to so meant the USAF swallowed the cost of a fuel supply chain, from refinery through tanks to tanker aircraft dedicated to SR71 support.

That is no longer viable. My guess is they are looking at doing this with regular JP4.

Personally with the huge advances in metallurgy, cooling and spray technologies (along with their associated modelling) in the last 60 odd years I think this is a relatively unambitious goal.

And you'd still have to be an aircraft around it. IE an SR71 Mk II.
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 09/23/2015 03:09 pm
There's a lot more to that story than is reported in the extract, but you'll need to track down the full article. Also there is a picture of the engine itself featured in the full article.

Anyway here's another extract from it.

Quote
The initial phases of the program focused on inlet performance and stability at Mach 4, which took up 95% of the early testing. Mode transition schedules were developed during tests in 2011-12, and a Mach 3 bleed configuration was created to help solve a high steady state distortion that was discovered at Mach 3. The goal of the latest phase was to focus on smooth and stable mode transition at Mach 3 and test a closed-loop inlet control system in the process. Walker says the program completed system identification of inlet dynamics for development of controls algorithms and “successfully demonstrated a fully autonomous mode transition with no unstarts.” This latest phase of testing was completed in May.
Stelr is also one of the propulsion options included in a NASA-funded Lockheed Martin study in support of the proposed SR-72 hypersonic, ISR strike aircraft. The study has been looking into the viability of a TBCC propulsion system with several combinations of “near-term turbine engine solutions” and a very-low-Mach ignition dual mode ramjet. Unlike the Mach 4 takeover range of most ramjets conceived to date, this study, together with another similar contract recently awarded by NASA to Aerojet Rocketdyne, is evaluating take-over velocity to be reduced to Mach 2.5 and below.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Archibald on 10/08/2015 02:46 pm
He might have not been involved with Skylon, but 30 years ago he helped HOTOL to get of the ground. Peter Conchie has died on August 22, 2015
http://aerosociety.com/News/Society-News/3582/OBITUARY-PETER-CONCHIE
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 10/13/2015 03:10 pm
The IAC update seems to have happened but I can't find any crumbs of news or comments about it:

https://iafastro.directory/iac/paper/id/31601/summary/
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 10/15/2015 07:29 pm
The IAC update seems to have happened but I can't find any crumbs of news or comments about it:

https://iafastro.directory/iac/paper/id/31601/summary/

Here's the paper, a pretty good read I think.

It covers a lot of stuff we pretty much already knew but it's nice to see it all set out together in a paper.

SABRE 4 is what we thought with all the trade-offs we discussed and and they're working at bringing down the cost of making everything.

Things that jumped out at me as new:
A new SUS design
                  "This design is shorter and lighter than previous versions
                   increasing the allowable payload length from 4.4m to
                   8.6m and the reusable mode GTO payload from
                   6387kg to 7259kg. "

New mission modelling
                 "SKYLON D1 could place 17 tonnes into a 185 km circular orbit"

and
                " The vehicle can
                  recover to any airfield with compatible latitude at least
                 6 times per day from any orbit, and can recover to an
                 Equatorial airfield from a low inclination orbit (less
               than 40 degrees) on any pass. It was also found that
                the vehicle is capable of operating from any airfield,
               overflying any location on Earth, and recovering to the
              same airfield within a single orbit."


Now I wonder who would find that last part useful?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 10/15/2015 11:00 pm
The IAC update seems to have happened but I can't find any crumbs of news or comments about it:

https://iafastro.directory/iac/paper/id/31601/summary/
                " The vehicle can
                  recover to any airfield with compatible latitude at least
                 6 times per day from any orbit, and can recover to an
                 Equatorial airfield from a low inclination orbit (less
               than 40 degrees) on any pass. It was also found that
                the vehicle is capable of operating from any airfield,
               overflying any location on Earth, and recovering to the
              same airfield within a single orbit."


Now I wonder who would find that last part useful?
Actually anyone who's serious about servicing an on orbit asset, like a hotel for example, or collecting   the results of an on orbit manufacturing plant.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 10/16/2015 10:58 am
The IAC update seems to have happened but I can't find any crumbs of news or comments about it:

https://iafastro.directory/iac/paper/id/31601/summary/

Here's the paper, a pretty good read I think.

I think it's fascinating that as we find out how frost control works.....it's suddenly irrelevant :-).  So much thinking and wondering about what it was and all for nothing.

Also thrust vectoring seems to be mentioned very often in papers that I found on Google about Dual Throat Nozzles.  I wonder if they intend to use it?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 10/16/2015 12:30 pm
...
Also thrust vectoring seems to be mentioned very often in papers that I found on Google about Dual Throat Nozzles.  I wonder if they intend to use it?

Could you say more? Skylon designs have always had gimbaling nozzles as far as I know. What would be different about dual throat nozzles with SABRE 4?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 10/16/2015 12:35 pm
The IAC update seems to have happened but I can't find any crumbs of news or comments about it:

https://iafastro.directory/iac/paper/id/31601/summary/
                " The vehicle can
                  recover to any airfield with compatible latitude at least
                 6 times per day from any orbit, and can recover to an
                 Equatorial airfield from a low inclination orbit (less
               than 40 degrees) on any pass. It was also found that
                the vehicle is capable of operating from any airfield,
               overflying any location on Earth, and recovering to the
              same airfield within a single orbit."


Now I wonder who would find that last part useful?
Actually anyone who's serious about servicing an on orbit asset, like a hotel for example, or collecting   the results of an on orbit manufacturing plant.
That's a different problem, surely: being able to overfly any point on the Earth and land in one orbit is not the same as being able to rendezvous with an orbiting asset in one orbit.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 10/16/2015 12:52 pm
...
Also thrust vectoring seems to be mentioned very often in papers that I found on Google about Dual Throat Nozzles.  I wonder if they intend to use it?

Could you say more? Skylon designs have always had gimbaling nozzles as far as I know. What would be different about dual throat nozzles with SABRE 4?

I'm a layperson and what I could say isn't worth reading but... I did read up about a UAV project in the UK once that was aimed at demonstrating "fluidic" controls - FLAVIR.    As I understand it, fluidic vectoring uses smaller flows e.g. at the side of an exhaust, to influence the direction of the main flow.   How this works with dual-throat nozzles, I don't understand but there are a lot of papers about it e.g. from NASA.

The result, as I understand it, is a much lighter system than mechanical thrust vectoring and the more vectoring you have the less control surfaces you need so you get less drag.  But again I am an ignoramus and I'm just typing what I have inexpertly read about.  It may not make any sense for the part of SABRE4 which is basically rocket-like rather than jet-like.
 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 10/16/2015 01:42 pm
I think it's fascinating that as we find out how frost control works.....it's suddenly irrelevant :-).  So much thinking and wondering about what it was and all for nothing.

Also thrust vectoring seems to be mentioned very often in papers that I found on Google about Dual Throat Nozzles.  I wonder if they intend to use it?
I'd be surprised at that.

The FLAVIR work you mentioned is not a dual throat nozzle. It's a main flow with 2 side flows, which use fluidic effects (the Coanda effect particularly IIRC) to divert the  main thrust up or down (or in principle with another set of side flow channels left or right). In theory the payoff is smaller, faster valves shift the control flow, which shifts the main flow.

But a dual chamber nozzle is truly one chamber inside the other, a bell within a bell.

The only one of these I'm aware of was the Lance tactical missile. The centre bell was the 50 000lb  booster to get off the launcher then the outer bell (technically an annular combustion chamber) gave 5000lb for cruising.

Development had some problems but I suspect that had more to do with the storable propellants, ablative cooling and long series mfg than the actual concept. Since SABRE engines are not ablattively cooled or use storables I think most of those problems would be absent.

[EDIT BTW FLAVIR was a remarkable programme. Most of the work resulted in actual flight vehicles, although by normal standards they were tiny. ]
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 10/16/2015 10:29 pm
On page 3 of the report it says:

**Also, due to the higher pre-cooler exit temperature compared to SABRE 3, the frost control system is no longer required.**

?? What exactly does that mean? They're not getting rid of the heat exchangers, so why don't they need the frost control? Below 0 C and ice forms. Why don't they need frost control now? What temperature will the heat exchangers reduce the intake airflow down to in SABRE 4?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 10/16/2015 10:49 pm
The thing with SABRE 3 was that it used the same combustion chamber and nozzle for airbreathing mode as for rocket mode.  This meant that the airbreathing pressure ratio had to be very very high, which meant that the air going into the big end of the compressor had to be very very cold if the small end of the compressor was to survive very long.

Now that they're using a separate chamber, that opens up partway down the nozzle, they don't need rocket-class chamber pressures, so the pressure ratio is lower and the air can be much warmer before compression without damaging the engine.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 10/16/2015 11:17 pm
On page 3 of the report it says:

**Also, due to the higher pre-cooler exit temperature compared to SABRE 3, the frost control system is no longer required.**

?? What exactly does that mean? They're not getting rid of the heat exchangers, so why don't they need the frost control? Below 0 C and ice forms. Why don't they need frost control now? What temperature will the heat exchangers reduce the intake airflow down to in SABRE 4?
If you read the patent on SABRE 4 you'll see that in this cycle the precooler exit temperature is designed to never fall below 400K with the bidirectional valve in the cycle directing helium around the precooler to maintain that. 


The IAC update seems to have happened but I can't find any crumbs of news or comments about it:

https://iafastro.directory/iac/paper/id/31601/summary/
                " The vehicle can
                  recover to any airfield with compatible latitude at least
                 6 times per day from any orbit, and can recover to an
                 Equatorial airfield from a low inclination orbit (less
               than 40 degrees) on any pass. It was also found that
                the vehicle is capable of operating from any airfield,
               overflying any location on Earth, and recovering to the
              same airfield within a single orbit."


Now I wonder who would find that last part useful?
Actually anyone who's serious about servicing an on orbit asset, like a hotel for example, or collecting   the results of an on orbit manufacturing plant.

I was thinking more along the lines of being able to responsively launch a Skylon with an ISR package in the payload bay and have it overfly any location on Earth from an airfield in CONUS.

My query about the engines is are they throttling by translating the nozzle adjusting throat area, we know it has to translate anyway and this is something I believe has been explored before with this type of nozzle.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 10/17/2015 12:51 am
I was thinking more along the lines of being able to responsively launch a Skylon with an ISR package in the payload bay and have it overfly any location on Earth from an airfield in CONUS.
Given the expanded latitude range that would certainly seem to be possible.

Note that right now the only payload REL are committed to supplying (not necessarily building) is the Skylon Upper Stage.

Any operator, or customer of an operator, would have to supply that hardware themselves. I'd also not that under normal circumstances there is no reason for Skylon to fly "upside down." However an "Earth Observation" mode could be included in the standard flight control software to roll the vehicle 180deg, open its doors and then close and roll it backward.
Quote
My query about the engines is are they throttling by translating the nozzle adjusting throat area, we know it has to translate anyway and this is something I believe has been explored before with this type of nozzle.
A running theme of REL work has been to push the SoA  (or the common state of practice) only where absolutely necessary.

I'm not quite clear what you're suggesting. Do you mean some kind of Pintle injector? Making the whole inner chamber some kind of pintle?

Conventional practice has the whole engine gimbal but people have done engines where only the thrust chamber(s) move, although this needs high pressure fluid gimbals rated to chamber pressure, not tank pressure.

For throttling I'd guess they can either indirectly throttle the pump drive turbines by controlling heat addition through the pre burner or (with a more direct action) have divert valves to divert some of the propellants back to the pump inlets. These techniques have history going back to the RL10 and J2 (and possibly the RZ20 built by Rolls Royce in the late 60's).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 10/17/2015 09:35 am
Ikm
**If you read the patent on SABRE 4 you'll see that in this cycle the precooler exit temperature is designed to never fall below 400K with the bidirectional valve in the cycle directing helium around the precooler to maintain that.**

Ah, 400K, I see. That's well above freezing point. Thanks for the info. :)    Well, so much for the frost control!

@93143
I understood that the noozles were now separated in SABRE 4 and that had changed the thermodynamics of the flows. I just wasn't clear on what the pre-cooler exit temperature was. I just figured (before I saw the report) that the precooler still brought the airflow down below 0C. I guess they have much more control over the heat-exchanger thermodynamics than I imagined.  (As an aside, I wonder how much on-the-fly control could be engineered into such a system).

BTW, your explanation also gave me a better understanding of the system. Many thanks!
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 10/17/2015 10:00 am
I was thinking more along the lines of being able to responsively launch a Skylon with an ISR package in the payload bay and have it overfly any location on Earth from an airfield in CONUS.
Given the expanded latitude range that would certainly seem to be possible.

Note that right now the only payload REL are committed to supplying (not necessarily building) is the Skylon Upper Stage.

Any operator, or customer of an operator, would have to supply that hardware themselves. I'd also not that under normal circumstances there is no reason for Skylon to fly "upside down." However an "Earth Observation" mode could be included in the standard flight control software to roll the vehicle 180deg, open its doors and then close and roll it backward.

My thinking was these are their latest mission analysis studies conducted since they began their relationship with the AFRL and perhaps this was indicative of the sorts of questions they were asking.
 
My query about the engines is are they throttling by translating the nozzle adjusting throat area, we know it has to translate anyway and this is something I believe has been explored before with this type of nozzle.
A running theme of REL work has been to push the SoA  (or the common state of practice) only where absolutely necessary.

I'm not quite clear what you're suggesting. Do you mean some kind of Pintle injector? Making the whole inner chamber some kind of pintle?

Conventional practice has the whole engine gimbal but people have done engines where only the thrust chamber(s) move, although this needs high pressure fluid gimbals rated to chamber pressure, not tank pressure.

For throttling I'd guess they can either indirectly throttle the pump drive turbines by controlling heat addition through the pre burner or (with a more direct action) have divert valves to divert some of the propellants back to the pump inlets. These techniques have history going back to the RL10 and J2 (and possibly the RZ20 built by Rolls Royce in the late 60's).

The SABRE 4 ends the airbreathing mode by translating the entire airbreathing nozzle backwards until the airbreathing throat closes, as it does so the area of the airbeathing throat decreases. Other expansion-deflection nozzles designs  throttle thrust by varying the throat area through translating the pintle so if the SABRE 4 airbreathing chambers move with the nozzle then the SABRE 4 can throttle thrust in the same manner. So in a sense that is the SoA for ED nozzles.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 10/17/2015 11:31 pm
do you expect substantial costs reduction from getting rid of frost control?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 10/18/2015 09:20 am

The IAC update seems to have happened but I can't find any crumbs of news or comments about it:

https://iafastro.directory/iac/paper/id/31601/summary/
                " The vehicle can
                  recover to any airfield with compatible latitude at least
                 6 times per day from any orbit, and can recover to an
                 Equatorial airfield from a low inclination orbit (less
               than 40 degrees) on any pass. It was also found that
                the vehicle is capable of operating from any airfield,
               overflying any location on Earth, and recovering to the
              same airfield within a single orbit."


Now I wonder who would find that last part useful?
Actually anyone who's serious about servicing an on orbit asset, like a hotel for example, or collecting   the results of an on orbit manufacturing plant.
That's a different problem, surely: being able to overfly any point on the Earth and land in one orbit is not the same as being able to rendezvous with an orbiting asset in one orbit.

I imagine the USAF took note of that, or rather were already aware of that.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 10/18/2015 05:11 pm
do you expect substantial costs reduction from getting rid of frost control?
Probably not much.

You've sunk the funds getting it to work. The HX's will be a bit simpler but I suspect not much simpler. The bulk of them will still be the LH2 network and that's going to be get much simpler.
I think it's fascinating that as we find out how frost control works.....it's suddenly irrelevant :-).  So much thinking and wondering about what it was and all for nothing.
Apparently so. But note it's taken REL about 30 years to get here and AFAIK all other groups working in this area (and there are a small number) tagged air cooling and frost control as the problems for these kinds of engines.

The attraction was you traded engine complexity for weight which meant less deadweight to get to orbit as you'd burnt off the LH2.

Trading higher engine weight for lower fuel is not an intuitively obvious way to go. You have to dig deep into the thermodynamics and engineering to get there, and only then can you discard the frost control.
My thinking was these are their latest mission analysis studies conducted since they began their relationship with the AFRL and perhaps this was indicative of the sorts of questions they were asking.
Probably not.

The work with ARFL was for SABRE, the engine.

These analyses apply to SKylon, the vehicle, which AFAIK had nothing do to with the AFRL contract.

However it is interesting they validated their trajectory analysis codes against a NASA system, although It's not clear where they got that from. Quite a lot of NASA stuff is available as source code (like their combustion modelling codes).


Quote

The SABRE 4 ends the airbreathing mode by translating the entire airbreathing nozzle backwards until the airbreathing throat closes, as it does so the area of the airbeathing throat decreases. Other expansion-deflection nozzles designs  throttle thrust by varying the throat area through translating the pintle so if the SABRE 4 airbreathing chambers move with the nozzle then the SABRE 4 can throttle thrust in the same manner. So in a sense that is the SoA for ED nozzles.
I think you're talking about the inlet end of SABRE. While it's technically a pintle I think most people call it an aerospike. I imagine changing overall air flow is part of the throttling process and that's certainly going to be part of the design for the ground test engine.

While REL's work does seem to have a pintle in the core of the test engines it looks like a straight cylinder to me and I suspect they'll want to keep the engine throttling process as simple as possible.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 10/18/2015 06:00 pm
do you expect substantial costs reduction from getting rid of frost control?
Probably not much.

You've sunk the funds getting it to work. The HX's will be a bit simpler but I suspect not much simpler. The bulk of them will still be the LH2 network and that's going to be get much simpler.
There is the benefit that you've lost a fourth liquid system from the engine which operationally must mean lower maintenance costs.


My thinking was these are their latest mission analysis studies conducted since they began their relationship with the AFRL and perhaps this was indicative of the sorts of questions they were asking.
Probably not.

The work with ARFL was for SABRE, the engine.

These analyses apply to SKylon, the vehicle, which AFAIK had nothing do to with the AFRL contract.

However it is interesting they validated their trajectory analysis codes against a NASA system, although It's not clear where they got that from. Quite a lot of NASA stuff is available as source code (like their combustion modelling codes).
AFRL is also looking at vehicle concepts.


The SABRE 4 ends the airbreathing mode by translating the entire airbreathing nozzle backwards until the airbreathing throat closes, as it does so the area of the airbeathing throat decreases. Other expansion-deflection nozzles designs  throttle thrust by varying the throat area through translating the pintle so if the SABRE 4 airbreathing chambers move with the nozzle then the SABRE 4 can throttle thrust in the same manner. So in a sense that is the SoA for ED nozzles.
I think you're talking about the inlet end of SABRE. While it's technically a pintle I think most people call it an aerospike. I imagine changing overall air flow is part of the throttling process and that's certainly going to be part of the design for the ground test engine.

While REL's work does seem to have a pintle in the core of the test engines it looks like a straight cylinder to me and I suspect they'll want to keep the engine throttling process as simple as possible.

No, I'm talking about the engine nozzle, the patent for it makes it clear. Pintle or centrebody is what I've read it as in ED papers.
Quote
"19. A nozzle arrangement according to claim 1, further comprising an actuator arrangement that is arranged to move the second portion of the nozzle between the two positions. "
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 10/18/2015 07:13 pm
lkm may know a better source, but here are links to the nozzle patent application and figures:

Text:
http://www.freshpatents.com/-dt20150416ptan20150101337.php

Figures:
http://images1.freshpatents.com/imageviewer/20150101337-p20150101337

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Bubbacub on 10/18/2015 08:01 pm
The last few pages of this thread (in which I've been lurking for years) have got me thinking. It seems as if the cooling requirements have decreased significantly since the change in engine design from sabre 3 to sabre 4, so much so that frost control is no longer an issue.

My question is if this decrease in cooling requirements could allow for a change to methane as a the cryogenic fuel. This could significantly reduce the size and weight of skylon's tanks (and reduce the developmental costs and headaches from dealing with liquid H2). Of course a smaller skylon would make re-entry more difficult - if you believe reaction engines understanding of atmospheric re-entry.

I know that the trades around reduced ISP and increased propellant density are complex. However there does seem to be a recent trend, given today's tank building expertise and from lessons learnt from designs like, for example, the x33 to compromise with a lower ISP fuel to gain a benefit from the reduction in weight of tankage and insulation etc.

Over a 200 cycle lifetime there would also probably be fairly significant cost savings not only in terms of the cost of fuel but also the systems and infrastructure required to store and pump the fuel at the various launch sites.

Is this an obviously answerable question? Or is it something that could go either way and would require a complete vehicle redesign and modelling to answer?

In any event I thought it was something worth thinking about - especially given how reaction engines have demonstrated great flexibility in their thought processes by deciding to ditch frost control - a technology which they have spent the better part of twenty years perfecting. It takes a lot of strength of will and character to ditch the fundamental, truly unique part of their business in order to optimise the final vehicle. If they are willing to ditch frost control perhaps they would be willing to ditch liquid hydrogen?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hanelyp on 10/18/2015 08:33 pm
My impression is that while Sabre 4 uses less hydrogen than earlier designs, it still uses an excess of fuel for cooling.  For the same amount of cooling methane will save little if any tank volume, and greatly increase fuel weight.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 10/18/2015 11:20 pm
The last few pages of this thread (in which I've been lurking for years) have got me thinking. It seems as if the cooling requirements have decreased significantly since the change in engine design from sabre 3 to sabre 4, so much so that frost control is no longer an issue.

My question is if this decrease in cooling requirements could allow for a change to methane as a the cryogenic fuel. This could significantly reduce the size and weight of skylon's tanks (and reduce the developmental costs and headaches from dealing with liquid H2). Of course a smaller skylon would make re-entry more difficult - if you believe reaction engines understanding of atmospheric re-entry.

I know that the trades around reduced ISP and increased propellant density are complex. However there does seem to be a recent trend, given today's tank building expertise and from lessons learnt from designs like, for example, the x33 to compromise with a lower ISP fuel to gain a benefit from the reduction in weight of tankage and insulation etc.

Over a 200 cycle lifetime there would also probably be fairly significant cost savings not only in terms of the cost of fuel but also the systems and infrastructure required to store and pump the fuel at the various launch sites.

Is this an obviously answerable question? Or is it something that could go either way and would require a complete vehicle redesign and modelling to answer?

In any event I thought it was something worth thinking about - especially given how reaction engines have demonstrated great flexibility in their thought processes by deciding to ditch frost control - a technology which they have spent the better part of twenty years perfecting. It takes a lot of strength of will and character to ditch the fundamental, truly unique part of their business in order to optimise the final vehicle. If they are willing to ditch frost control perhaps they would be willing to ditch liquid hydrogen?

I've actually looked at this a bit, as much as I'm able to. I was interested in the possibility of using gelled hydrogen to improve volumetric isp, that's mixing liquid hydrogen with a second denser fuel to create a cryogenic slush that behaves like a solid in the tank but like a liquid when pumped.

I considered propane, methane and ammonia gels and found that optimised for payload fraction hydrogen performs better than either of the hydrocarbon gels but that that an ammonia/hydrogen gel might actually improve performance. However I'm not sure  if NH3/H2 gels are possible or how they behave.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 10/19/2015 08:34 am
Keep in mind that Skylon's aspect ratio is already below the minimum-drag point, and it can't get any narrower because of the payload bay spec.  And since it airbreathes to Mach 5, drag losses are actually fairly substantial - even now I don't think the tankage uses all of the available space (don't quote me on that).  I'm not sure a change to a denser propellant would do much, other than reduce the Isp and perhaps complicate the system.

I might be wrong - how in-depth were your calculations?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 10/19/2015 10:21 am
Keep in mind that Skylon's aspect ratio is already below the minimum-drag point, and it can't get any narrower because of the payload bay spec.  And since it airbreathes to Mach 5, drag losses are actually fairly substantial - even now I don't think the tankage uses all of the available space (don't quote me on that).  I'm not sure a change to a denser propellant would do much, other than reduce the Isp and perhaps complicate the system.

I might be wrong - how in-depth were your calculations?
Not nearly well enough to convincingly answer the question.
I calculated the engine performance using propep for each combination at incremental mixture ratios then calculated the propellant load for each one over the C1 trajectory then generated a structural mass using some guesstimated MERS created from the C1 and D1 data we have and the papers on Skylon structure.
Because I was more interested in vehicle size than payload I abandoned payload bay specs and maintained aspect ratio recalculating bay size accordingly using the prop load to calculate tank volume and mass and to size the aeroshell volume and surface area (modelled as a sears-haack body). I was also modelling for a smaller gross take off mass as the SABRE cycles I created for these prop combinations ran at a 3:1 ratio with air and so would be lower thrust.
So as you can see lots of places for me to go wildly wrong in my assumptions.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 10/20/2015 07:14 am
There is the benefit that you've lost a fourth liquid system from the engine which operationally must mean lower maintenance costs.
True, and not to be underestimated. But Methanol, unlike say the Anhydrous Ammonia on the Shuttle boiler, is fairly easy to handle at room temperature and pressure, so I'd guess the saving would be limited.  That said simpler is usually better.
Quote
AFRL is also looking at vehicle concepts.
I missed that, AFAIK the focus was the SABRE 3 cycle on the engine. Any vehicle studies would have presumably used that as their baseline.
Quote
No, I'm talking about the engine nozzle, the patent for it makes it clear. Pintle or centrebody is what I've read it as in ED papers.
Quote
"19. A nozzle arrangement according to claim 1, further comprising an actuator arrangement that is arranged to move the second portion of the nozzle between the two positions. "
Anything is possible but this sounds more like one of those "cover all the bases" clauses that patent drafters like to use.


Looking at the drawings you posted you're talking about a movable combustion chamber within an outer combustion chamber.

As a way to throttle thrust this seems be a)Mechanically very complex b)Lots of high temperature and pressure engineering combined with lots of cryogenic engineering. c) Large forces would need to be exerted to move one chamber inside another while operating.

On the basis that REL likes to avoid unnecessary complexity I  think they will stick to throttling by valves on the propellants or hot drive gas (which is inert, rather than super heated steam) supplies. There may be non obvious benefits to moving chamber design, but they'd have to be very substantial to justify the design risk.


Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 10/20/2015 06:05 pm

No, I'm talking about the engine nozzle, the patent for it makes it clear. Pintle or centrebody is what I've read it as in ED papers.
Quote
"19. A nozzle arrangement according to claim 1, further comprising an actuator arrangement that is arranged to move the second portion of the nozzle between the two positions. "
Anything is possible but this sounds more like one of those "cover all the bases" clauses that patent drafters like to use.


Looking at the drawings you posted you're talking about a movable combustion chamber within an outer combustion chamber.

As a way to throttle thrust this seems be a)Mechanically very complex b)Lots of high temperature and pressure engineering combined with lots of cryogenic engineering. c) Large forces would need to be exerted to move one chamber inside another while operating.

On the basis that REL likes to avoid unnecessary complexity I  think they will stick to throttling by valves on the propellants or hot drive gas (which is inert, rather than super heated steam) supplies. There may be non obvious benefits to moving chamber design, but they'd have to be very substantial to justify the design risk.




It's definitely the outer nozzle that translates.
Quote
FIG. 3 shows a representative one of the nozzles 10 in the rocket mode. In this mode, the second nozzle portion 40 is positioned in the rocket position. In this position, the second nozzle portion 40 is positioned relative to the inner nozzle portion 30 such that the annular throat 50 is closed. In other words, the second nozzle portion 40 is translated to the right in FIG. 3 relative to the first nozzle portion 30. This is such that the generally frusto-conical sections of the two nozzle portions 30, 40 no longer overlap and instead form a contiguous diverging rocket nozzle similar in shape to a conventional rocket nozzle (although it will be noted that the cylindrical section 43 of the second portion 40 still overlaps the first portion 30).

But re-reading the patent it's clear that the airbreathing chambers are fixed relative to the rocket chamber so it can't throttle by varying the throat diameter while operating, somehow in my memory it had been ambiguous.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 10/21/2015 01:59 am
{snip}
If you read the patent on SABRE 4 you'll see that in this cycle the precooler exit temperature is designed to never fall below 400K with the bidirectional valve in the cycle directing helium around the precooler to maintain that. 

400K is 126°C (260°F) which is above the boiling point of water. Could nitrogen be used instead of helium at those temperatures?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 10/21/2015 06:21 am
Could nitrogen be used instead of helium at those temperatures?

Maybe, but it would have to reliably not plug a heat exchanger with liquid hydrogen on the other side, even during startup and shutdown.  Sounds potentially dicey to me.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 10/21/2015 02:54 pm
Could nitrogen be used instead of helium at those temperatures?

Maybe, but it would have to reliably not plug a heat exchanger with liquid hydrogen on the other side, even during startup and shutdown.  Sounds potentially dicey to me.
The liquid hydrogen heat exchanger cools the helium down to 50k so if it was nitrogen it would freeze.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 10/22/2015 07:18 am
Could nitrogen be used instead of helium at those temperatures?

Maybe, but it would have to reliably not plug a heat exchanger with liquid hydrogen on the other side, even during startup and shutdown.  Sounds potentially dicey to me.
Indeed. N2 is cheaper but for a relatively small volume closed cycle function like this it seems to add a lot of complexity for a very limited gain. 

It mightmake more sense if they switched to Methane but then you take a hit on Isp in rocket mode, which REL have stated is where Isp really counts.

Kourou has on site LH2 facilities from the Ariane 5 programme (and it looks like they will be retained for the current Ariane 6 plan). My instinct is they will stay LH2
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 10/22/2015 08:25 am
Reading the current report give a few more intriguing nuggets.

Quote
a change control board has been established and all of the requirements have been moved from paper
specifications to a computer based requirements tracking programme.
.....
The formal change control process was also required to enable compliance with the emerging
certification requirements.

The board consists of members of the Reaction Engines System engineering team and ESA personnel
representing the customers’ interests.

This suggests are REL are quite serious about firming up the design of Skylon and that any requirements that Skylon will have to meet will have an audit trail showing where they came from and why.

Note that ESA personnel are acting as customers to give the customer PoV. Ariane 6 remains the programme of record.

The SUS design has been revised

Quote
This design is shorter and lighter than previous versions increasing the allowable payload length from 4.4m to 8.6m and the reusable mode GTO payload from 6387kg to 7259kg. 


Which I think puts it on a level playing field with the Ariane 6 target.

The heavier SABRE design and reduced LH2 storage makes for a denser Skylon and it seems CoG limits the allowed AoA even more.

Quote
Both these factors were expected to increase the predicted skin temperatures. However the new
modelling also incorporated the results computational fluid dynamics analysis of SKYLON and in practice
the resulting temperatures similar to earlier C1 reentry models.

If they are referring to the fuselage temperatures from the engines during takeoff in the DLR CFD studies this suggests that they can keep skin temp in the C1 range by narrowing the allowed AoA, which it seems they have to do anyway.

On the foil blanket

Quote
The multi-foil blanket that lies between the aeroshell and truss structure has been looked at and a
new method of construction devised which makes its integration into the vehicle easier and more reliable.
Previously it was assumed that each foil layer would be laid one at a time. The new approach creates the
monolithic block of foils and spacers all of which are integrated in one piece.

This really surprised me as I'd always assumed these blankets were made as multilayer structures before being installed as complete units.

Making them off vehicle should simplify their mfg quite a lot. The only down side I can see would be if the edges are sealed they you have a thermal short cut from the front to the back faces. Obviously the bigger the pieces the fewer the number of these.

Another surprise was this.

Quote
An examination of the SKYLON power and data harness was started in April 2015. This project was
tasked to establish a realistic harness mass for the SKYLON airframe. This follows a late realisation that
the mass of the electrical and optical harness is likely to exceed the total mass of the units that it serves, and therefore it is an important component of system viability. 

This is quite extraordinary.

IIRC outside of the cutting edge low TRL stuff REL used scaled masses from the HOTOL programme for things like this.

This implies either the mass of LRU's to carry out the planned functions has gone down a lot in the years since HOTOL (plausible with the growth of MEMS sensors with an on chip CANbus interface for example) to the point where the cabling is now a significant fraction of the system mass, or so many more parameters have to be monitored the number of cables to carry this data has ballooned.

Historically ARINC and MilStd busses have been point to point with data rates in the 100kbs to 1mbs range. The newer 1773b is fibre optic and good to 20mbs and Spacewire to 400mbs. Of course now that 1Gbs star connected Ethernet is commonplace for offices and switches and routers are available in very small packages (some aerospace rated) is certainly an option. However given REL's aim to avoid cutting edge tech where possible I think they'll go with more (but not completely) conservative approaches.

While surprising I will note that so much of SABRE/Skylon has been tested in a computer I would expect this concern to be dealt with long  before any hardware is built.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 10/24/2015 08:47 am
I understood REL's reluctance to be on making claims based on unproven technologies. SpaceX have demonstrated the use of networking technologies to reduce wiring complexity and weight.
Actually the use of Ethernet and small form factor industrial PC's (104 form factor, IE about 4 inches square) goes back to the Orbital Pegaus.

There are are recognized "Avionics Data Networking" standards that are good to at least 100mbs with full dual redundancy and controllable latency and timing variability .

The joker in the pack is radiation.

ELV's spend most of their time inside the Earths protective magnetic field. They don't complete a single orbit so don't have to face the radiation barrage of the South Atlantic Anomaly and they don't have a planned 200 flight life expectancy, which could cause hard errors to accumulate. The OBC's of the Dragon capsule are about the closest SX have come to this so far. AIUI these rebooted fairly regularly but there were enough of them running to maintain a working capsule at all times.  The most demanding systems will likely be the SUS, which will have to perform complex rendezvous motions after exposure to the radiation environment in near GEO orbit.

The fact comm sats operate for decades in this environment indicates the problems can be handled, at a price.

We will have to see wheather REL goes for a "rad hard by construction" design IE made on a rad hard process, like the 1750A's used by ULA, or a more rad tolerant by design approach using more mainstream parts.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: dchill on 10/24/2015 02:58 pm
I understood REL's reluctance to be on making claims based on unproven technologies. SpaceX have demonstrated the use of networking technologies to reduce wiring complexity and weight.
Actually the use of Ethernet and small form factor industrial PC's (104 form factor, IE about 4 inches square) goes back to the Orbital Pegaus.

There are are recognized "Avionics Data Networking" standards that are good to at least 100mbs with full dual redundancy and controllable latency and timing variability .

The joker in the pack is radiation.

ELV's spend most of their time inside the Earths protective magnetic field. They don't complete a single orbit so don't have to face the radiation barrage of the South Atlantic Anomaly and they don't have a planned 200 flight life expectancy, which could cause hard errors to accumulate. The OBC's of the Dragon capsule are about the closest SX have come to this so far. AIUI these rebooted fairly regularly but there were enough of them running to maintain a working capsule at all times.  The most demanding systems will likely be the SUS, which will have to perform complex rendezvous motions after exposure to the radiation environment in near GEO orbit.

The fact comm sats operate for decades in this environment indicates the problems can be handled, at a price.

We will have to see wheather REL goes for a "rad hard by construction" design IE made on a rad hard process, like the 1750A's used by ULA, or a more rad tolerant by design approach using more mainstream parts.
Orion uses Time Triggered Gigabit Ethernet (TTGbE) for all its functions.  Here's an article that talks a bit about it (http://mil-embedded.com/articles/orion-avionics-designed-reliability-deep-space/# (http://mil-embedded.com/articles/orion-avionics-designed-reliability-deep-space/#)).  The TTGbE technology has now become an industry standard – SAE AS6802 and rad-hard ASICs are available.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 10/25/2015 09:47 am

Orion uses Time Triggered Gigabit Ethernet (TTGbE) for all its functions.  Here's an article that talks a bit about it (http://mil-embedded.com/articles/orion-avionics-designed-reliability-deep-space/# (http://mil-embedded.com/articles/orion-avionics-designed-reliability-deep-space/#)).  The TTGbE technology has now become an industry standard – SAE AS6802 and rad-hard ASICs are available.
Noted but the standard only has 1 design win with only 1 test flight of hours.

I'll also note that in principle REL has access to ESA's experience of networks in deep space probes. These are units with years of exposure to deep space outside the Earth's protective magnetic field.

REL are aware their project is high risk so they aim to minimize risk wherever possible. Putting their faith in a bus design with such limited flight experience would be unwise. That position might change  if the design acquires more flight experience before they have to freeze the Skylon design.

Note that unlike the Shuttle Skylon is designed to be statically stable, needing (relatively) low actuator command rates to the flight surfaces.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 10/26/2015 08:22 am
What's the main point of using ethernet though? Is it to reduce the number of cables or to increase the data rate?

I would imagine that you might have the essential flight controls and sensors on one low-latency, high reliability bus and the nice-to-haves on a high-throughput bus  e.g. cameras.

I also wonder how wireless sensor networks would function in space. e.g.
http://www.coventry.ac.uk/Global/05%20Research%20section%20assets/Research/Cogent%20Computing/PDFs%20for%20Publications/FMapNanotech.pdf
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: tl6973 on 10/26/2015 12:15 pm
What's the main point of using ethernet though? Is it to reduce the number of cables or to increase the data rate?

I read somewhere that it significantly reduces the overall mass of cabling required, in comparison to serial cabling. As for a reduction in the number of cables, I have no idea.

I would imagine that mass reduction, though important, is a secondary benefit in comparison to cost/complexity/ networking benefits
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: dchill on 10/26/2015 02:27 pm
Lockheed uses wireless sensor networks for DFI on the JSF and has proprietary results on the mass and labor savings from that, along with the benefits for not needing new wall penetrations, etc.   We've shared some of that info with Dream Chaser but it could also benefit other programs.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 10/26/2015 11:27 pm
Lockheed uses wireless sensor networks for DFI on the JSF and has proprietary results on the mass and labor savings from that, along with the benefits for not needing new wall penetrations, etc.   We've shared some of that info with Dream Chaser but it could also benefit other programs.
Interesting. Harvesting engine heat to power the sensors is a neat idea. The fact they are packed deep within the engine, itself packed deep within the fuselage, probably makes this a very cost effective option for the JSF design.

However Skylon's highly accessible engine pods and (relative) ease of replacement would probably shift the cost balance. The real issues for this technology are likely to be a) Very limited operating experience b)Unknown radiation tolerance (while an F35 could theoretically find itself on a nuclear battlefield SkylonSABRE will be be exposed to higher levels of radiation as part of normal operation, although most of this will be on orbit when the main engines will be off.
c)ITAR issues. With what looks like being the first application of this tech being the JSF this will be on the "dual use" list if not outright under "munitions."

I think this is just too new and too loaded with red tape for a non US non defense company to use.

Part of the issue with existing systems is that point to point wiring needs 2 part connectors at either end of the cabling regardless of how long that cabling is. Since the all run in parallel that can mean a lot of connectors. The question is how much real redundancy does this buy? Moving to a proper bus IE a shared transmission medium, probably with 2 or 3 separate and separately routed channels eliminates a lot of that connector mass, while a paths capable of supporting 100s of mbs has at least 4x the bandwidth of all the 25 segments of Shuttle bus combined.

I think just moving to what is now standard practice in the industry (compared with the SoA when HOTOL was  designed) will reduce mass substantially.

REL does not appear to like novelty for its own sake. I suspect they will aim to to make the new systems as light as needed but avoid any cutting edge technology where possible. That said since the HOTOL design was last looked at in 1986 things which have a 10 year operating history will still be 20 years more advanced than HOTOL.

[EDIT The networking architecture of the recently launched LISA pathfinder mission would seem to be a good model to study as this will be in a radiation environment relatively close to Earth (no dives into the upper Jupiter atmosphere for example) but well outside it's protective magnetic field. Spacewire seems to have been adopted as the hardware standard across all main space agencies ]
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 10/27/2015 07:04 pm
{snip}
I think just moving to what is now standard practice in the industry (compared with the SoA when HOTOL was  designed) will reduce mass substantially.

REL does not appear to like novelty for its own sake. I suspect they will aim to to make the new systems as light as needed but avoid any cutting edge technology where possible. That said since the HOTOL design was last looked at in 1986 things which have a 10 year operating history will still be 20 years more advanced than HOTOL.

[EDIT The networking architecture of the recently launched LISA pathfinder mission would seem to be a good model to study as this will be in a radiation environment relatively close to Earth (no dives into the upper Jupiter atmosphere for example) but well outside it's protective magnetic field. Spacewire seems to have been adopted as the hardware standard across all main space agencies ]

In which case REL will be able to buy off the shelf TRL 9 Spacewire components. Obsolescence can be handed by using an interface compatible part; either at the chip or circuit board level.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 10/28/2015 10:26 am
{snip}
I think just moving to what is now standard practice in the industry (compared with the SoA when HOTOL was  designed) will reduce mass substantially.

REL does not appear to like novelty for its own sake. I suspect they will aim to to make the new systems as light as needed but avoid any cutting edge technology where possible. That said since the HOTOL design was last looked at in 1986 things which have a 10 year operating history will still be 20 years more advanced than HOTOL.

[EDIT The networking architecture of the recently launched LISA pathfinder mission would seem to be a good model to study as this will be in a radiation environment relatively close to Earth (no dives into the upper Jupiter atmosphere for example) but well outside it's protective magnetic field. Spacewire seems to have been adopted as the hardware standard across all main space agencies ]

In which case REL will be able to buy off the shelf TRL 9 Spacewire components. Obsolescence can be handed by using an interface compatible part; either at the chip or circuit board level.
Provided it uses Spacewire, which I think is likely.

Note that since HOTOL never got into detail design both SABRE and Skylon will be clean sheet in this regard.

The challenge will be to balance what is needed with what you could have, swamping the system with data which is not strictly necessary to carrying out the core tasks. The classic mistake in this area was during Shuttle testing where there were issues around the tail flap. Unfortunately the instrumentation engineers had only budgeted about 1 sample per second for this to measure angle ( I think this was it could only be commanded to change angle quite slowly). However aerodynamic forces were large and the actual movement (as forced by the airflow) could be much faster.

In principal modern bus speeds should mean there will always be spare capacity to increase data rates if something needs faster sampling below the hardware design limit of the ADC. More precision will likely need a new converter board.

But at the back of my mind I'm thinking "640KB, more than enough for any  computer program home users will ever need"  :( .
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 10/29/2015 12:57 am
{snip}
The challenge will be to balance what is needed with what you could have, swamping the system with data which is not strictly necessary to carrying out the core tasks. The classic mistake in this area was during Shuttle testing where there were issues around the tail flap. Unfortunately the instrumentation engineers had only budgeted about 1 sample per second for this to measure angle ( I think this was it could only be commanded to change angle quite slowly). However aerodynamic forces were large and the actual movement (as forced by the airflow) could be much faster.

In principal modern bus speeds should mean there will always be spare capacity to increase data rates if something needs faster sampling below the hardware design limit of the ADC. More precision will likely need a new converter board.

But at the back of my mind I'm thinking "640KB, more than enough for any  computer program home users will ever need"  :( .

Packet networks run best when keep below 1/3 full. The other 2/3 can then be used to automatically sort out any congestion and empty the buffers after a data burst.
https://en.wikipedia.org/wiki/Long-tail_traffic#cite_note-r16-18 (https://en.wikipedia.org/wiki/Long-tail_traffic#cite_note-r16-18)

A satellite may operate with a constant data input but launch vehicles do not. LV do things like sitting on the launch pads for hours and then starting all their engines at the same time.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/01/2015 07:41 am
Packet networks run best when keep below 1/3 full. The other 2/3 can then be used to automatically sort out any congestion and empty the buffers after a data burst.
https://en.wikipedia.org/wiki/Long-tail_traffic#cite_note-r16-18 (https://en.wikipedia.org/wiki/Long-tail_traffic#cite_note-r16-18)

A satellite may operate with a constant data input but launch vehicles do not. LV do things like sitting on the launch pads for hours and then starting all their engines at the same time.
True, but what you're missing is that the process is much more structured than the kind of "bursty" traffic you see on internal networks or the general internet. SCADA networks are more likely to prefer smaller packets (IIRC the one packets on the Shuttle were often 32 bytes) as they don't need to need large files. The downside is the larger proportion of overhead but the upside is more consistency, which is important for control functions.

Another factor is the extent that data sources and sinks can be located on the same switches, so the data never needs to go across the main bus.

SABRE/Skylon is not the Shuttle. The big changes are the extent to which devices can have local processing to limit the data transfers. On the Shuttle star trackers, radar, inertial navigation, radar altimeters were all separate (large) boxes  Today quite a few of those boxes could be eliminated or combined into one.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: topsphere on 11/01/2015 09:42 pm
BAE buys 20% stake in Reaction Engines

Financial Times story here http://www.ft.com/cms/s/0/a25d2798-7f1b-11e5-98fb-5a6d4728f74e.html

I appreciate most people won't have an FT account, so the main points of the article:

- BAE Systems agree to buy a 20% stake in Reaction Engines Ltd worth £20.6m, which entitles them to a seat on the board and a position as "preferred supplier".

- The investment in REL will unlock a further £60m grant package from the UK government.

- However, the group has had to scale back its ambitions for a test engine in order to clinch the funding deal.

- The group now has "no immediate funding needs".
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 11/01/2015 11:03 pm
BAE buys 20% stake in Reaction Engines

Financial Times story here http://www.ft.com/cms/s/0/a25d2798-7f1b-11e5-98fb-5a6d4728f74e.html

I appreciate most people won't have an FT account, so the main points of the article:

- BAE Systems agree to buy a 20% stake in Reaction Engines Ltd worth £20.6m, which entitles them to a seat on the board and a position as "preferred supplier".

- The investment in REL will unlock a further £60m grant package from the UK government.

- However, the group has had to scale back its ambitions for a test engine in order to clinch the funding deal.

- The group now has "no immediate funding needs".
Well that must be the bargain of the century.
Given REL's potential to own a multi billion dollar industry plus it's significantly valuable IP which has wide commercial applications a valuation of 100 million pounds seems a little low.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Dreyrden on 11/01/2015 11:17 pm
There's also an article on the BBC here: http://www.bbc.co.uk/news/business-34694935

That's some pretty big news.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: topsphere on 11/02/2015 12:01 am
I agree that the valuation seems a little low, maybe there is something behind the scenes we are not being told about? I find the section saying this deal has secured BAE as "preferred supplier" for REL very interesting, they must be favourites to build the airframe now??

Also agreed that this is potentially very big news, as an aside it might be time soon to move these threads out of "Advanced Concepts", it seems a bit harsh on REL that they are in the same bracket as EM Drive and rotating space stations, despite developing into a very respectable company. Oh, and the BBC's decision to call them just "Reaction" annoyed me a little, but that's just me being cranky :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Asteroza on 11/02/2015 12:05 am
How far back are they scaling the test engine work though? That might hurt more than the funding help...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 11/02/2015 01:00 am
I'm not so sure this 'scaling back' is news, at least I doubt REL would put it in those terms. I say this because the FT article puts it this way: they say REL were hoping for £250M, and contrast that with what they have: £60+20M. But the authors may have got that £250M figure from a 2012 FT.com article linked from this one that begins "Aerospace engineer are seeking £250M..."

REL have in the past thrown around some large numbers for development funding, and I'm sure more is better, but it's unclear that the current £80M is a problem, or even leads to a delay. As topsphere already quoted, there are "no immediate funding needs."
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 11/02/2015 02:30 am
- BAE Systems agree to buy a 20% stake in Reaction Engines Ltd worth £20.6m, which entitles them to a seat on the board and a position as "preferred supplier".

Well that must be the bargain of the century.
Given REL's potential to own a multi billion dollar industry plus it's significantly valuable IP which has wide commercial applications a valuation of 100 million pounds seems a little low.

The obvious conclusion is that no big industry partner believed the odds of REL owning a multi-billion dollar industry were high.  Value equals size of payoff times probability of achieving the payoff.

How far back are they scaling the test engine work though? That might hurt more than the funding help...

Obviously REL doesn't believe it hurts more than it helps or they wouldn't have taken the deal.

This is undoubtedly good for REL.  It gives them far more funding than they've ever had before, and a big partner to give them respectability.  It's not the dream scenario REL fans would like, but it's something that lets them move forward and have a shot, even if it's a long shot.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 11/02/2015 04:01 am
The refrigeration technology may permit spinoffs. I wonder if there are any none aerospace applications that need rapid cooling to cryogenic temperatures?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Asteroza on 11/02/2015 04:30 am
The refrigeration technology may permit spinoffs. I wonder if there are any none aerospace applications that need rapid cooling to cryogenic temperatures?

The heat exchanger work miiiiight be applicable to recuperated jet engines, as some of the more advanced ultrahigh bypass ratio turbofan deigns are considering recuperation. Notably MTU, which had a ducted geared counterrotating propfan engine with recuperation (CLAIRE, CRISP, and NEWAC programs). Though that's dealing with turbine exhaust and compressor heat with an all air medium.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 11/02/2015 06:27 am

I agree that the valuation seems a little low, maybe there is something behind the scenes we are not being told about? I find the section saying this deal has secured BAE as "preferred supplier" for REL very interesting, they must be favourites to build the airframe now??

Also agreed that this is potentially very big news, as an aside it might be time soon to move these threads out of "Advanced Concepts", it seems a bit harsh on REL that they are in the same bracket as EM Drive and rotating space stations, despite developing into a very respectable company. Oh, and the BBC's decision to call them just "Reaction" annoyed me a little, but that's just me being cranky :)

Please don't throw around my concept is more respectable than your concept, as it ill becomes this part of the forum.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: FutureSpaceTourist on 11/02/2015 06:45 am
The REL website now has a press release and Sabre info graphic (attached).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 11/02/2015 06:51 am

I agree that the valuation seems a little low, maybe there is something behind the scenes we are not being told about? I find the section saying this deal has secured BAE as "preferred supplier" for REL very interesting, they must be favourites to build the airframe now??

Also agreed that this is potentially very big news, as an aside it might be time soon to move these threads out of "Advanced Concepts", it seems a bit harsh on REL that they are in the same bracket as EM Drive and rotating space stations, despite developing into a very respectable company. Oh, and the BBC's decision to call them just "Reaction" annoyed me a little, but that's just me being cranky :)

Please don't throw around my concept is more respectable than your concept, as it ill becomes this part of the forum.

What's wrong with discussing respectability?  Respectability matters.  It's a measure of the general feeling about a concept within some audience.  For any given audience, some concepts are considered realistic by more people than by others.

I think it's beyond doubt that among those who follow the aerospace industry and are aware of both REL and EmDrive, there's a lot more respect for REL's technology as a realistic concept than there is for EmDrive as a realistic concept.

People might be right or wrong to believe that, but there's no doubt that's what they believe, and it's silly to just pretend that's not true or try to silence anyone who wants to mention the fact.

The Advanced Concepts section exists so people who are interested in concepts that are generally considered less realistic can follow them there and others can avoid such concepts and follow other kinds of discussions.  Again, there's nothing wrong with that.  There's also nothing wrong with discussing whether any particular concept belongs in advanced concepts or not.

Any really new idea belongs in Advanced Concepts when it is first introduced.  If it eventually leads to an operational system, that operational system does not belong in Advanced Concepts.  At some point along the line, it has to move.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 11/02/2015 07:53 am
The refrigeration technology may permit spinoffs. I wonder if there are any none aerospace applications that need rapid cooling to cryogenic temperatures?

The heat exchanger work miiiiight be applicable to recuperated jet engines, as some of the more advanced ultrahigh bypass ratio turbofan deigns are considering recuperation. Notably MTU, which had a ducted geared counterrotating propfan engine with recuperation (CLAIRE, CRISP, and NEWAC programs). Though that's dealing with turbine exhaust and compressor heat with an all air medium.

I wonder how well it might work in suppressing IR signatures - if that's even not a ridiculous suggestion. Perhaps even being able to do so for a short time might be helpful.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 11/02/2015 08:11 am
The refrigeration technology may permit spinoffs. I wonder if there are any none aerospace applications that need rapid cooling to cryogenic temperatures?

The heat exchanger work miiiiight be applicable to recuperated jet engines, as some of the more advanced ultrahigh bypass ratio turbofan deigns are considering recuperation. Notably MTU, which had a ducted geared counterrotating propfan engine with recuperation (CLAIRE, CRISP, and NEWAC programs). Though that's dealing with turbine exhaust and compressor heat with an all air medium.

I wonder how well it might work in suppressing IR signatures - if that's even not a ridiculous suggestion. Perhaps even being able to do so for a short time might be helpful.

The REL heat exchanger is based on using liquid hydrogen to rapidly cool incoming air.  That makes sense for a vehicle using liquid hydrogen already as its fuel.  How applicable that would be to a vehicle using kerosene at room temperature as a fuel isn't clear.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 11/02/2015 08:28 am
It seems cheap to me too and there's the possibility that REL simply had no choice.   

This phrase, however, might be another way to look at it:
Quote
The working partnership will draw on BAE Systems’ extensive aerospace technology development and project management expertise and will provide Reaction Engines with access to critical industrial, technical and capital resources to progress towards the demonstration of a ground based engine – a key milestone in the development of the technology.

In other words REL can use their labs, factories, test equipment and perhaps things like wind tunnel time that one might not even be able to buy on the open market (I don't know this, I'm just guessing).  This path might be the only option for a UK company that can't afford the billions to set all that up independently.  So perhaps REL doesn't have enough money to pay BAE for borrowing its toys and BAE might not want to make money that way.   Instead a "cheap" investment might be even cheaper for BAE  if some of the money comes back to BAE in fees for use of it's infrastructure.  In fact, it might even be imaginable that more than £20 million would come back to them - some of the government money too.

For REL there's just the access to things that would cost an inordinate amount to have otherwise so that perhaps for them it is much more than a 20 million pound investment in a sense.

For the government.....well one supposes that there is some military aspect to all of this thanks to the AFRL work and other hints.  So it might want to ensure that a "UK" defense company (quotes because BAE has large foreign shareholdings IIRC) had a slice of that, and perhaps could benefit from the military aspect.   

Anyhow, as usual, when one knows nothing, speculation is great fun :-)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Ravenger on 11/02/2015 09:44 am
Interesting that that attached Infographic about the Sabre Engine is showing Sabre 3 with it's -150 C cooling requirement with frost control system, and not Sabre 4.

I thought Reaction Engines were probably going with with Sabre 4 which doesn't need to deep cool as much, so doesn't need the frost control system. The recent paper posted on here suggested they were.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 11/02/2015 11:37 am
- BAE Systems agree to buy a 20% stake in Reaction Engines Ltd worth £20.6m, which entitles them to a seat on the board and a position as "preferred supplier".

Well that must be the bargain of the century.
Given REL's potential to own a multi billion dollar industry plus it's significantly valuable IP which has wide commercial applications a valuation of 100 million pounds seems a little low.

The obvious conclusion is that no big industry partner believed the odds of REL owning a multi-billion dollar industry were high.  Value equals size of payoff times probability of achieving the payoff.
Sure but compared to some Silicon Valley unicorns REL has a better shot of owning it's market and the book value of its patents is surely more than the valuation put on the company. Hopefully the reality of this deal is that the majority of the financial value of this deal comes from the resources, both in people and infrastructure, that BAE has committed to providing. Over 4 years those could easily be worth several multiples of their cash investment.   
 
How far back are they scaling the test engine work though? That might hurt more than the funding help...

Obviously REL doesn't believe it hurts more than it helps or they wouldn't have taken the deal.

This is undoubtedly good for REL.  It gives them far more funding than they've ever had before, and a big partner to give them respectability.  It's not the dream scenario REL fans would like, but it's something that lets them move forward and have a shot, even if it's a long shot.

Except it's not more funding than they've ever had before.
I think up to the beginning of phase 3 they'd spent £100m and when the government investment was announced 2 years ago I believe it was said they already had £20m of private investment for the phase 3 round lined up, they must have already spent £35m from the first year of government investment plus some significant portion of private investment and if this BAE investment of £20.6m unlocks the remaining £25m of government money and completes phase 3 funding then either phase 3 costs have been cut by £150m or BAE investment is smaller than the combined value of all REL's other private investment this funding round.
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 11/02/2015 12:16 pm
One of the most important things about this is that a company as well known as BAE is willing to invest in them, in the first place.

I do think it also increases steeply the likelihood that military applications are paramount here knowing where BAE places it business focus these days. As it says in the link below BAE are primarily a defence company.

http://www.ibtimes.co.uk/bae-systems-buy-20-stake-reaction-engines-1526711

Now will they be able or wanting to attract other big investors perhaps someone like Airbus?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 11/02/2015 04:49 pm
One of the most important things about this is that a company as well known as BAE is willing to invest in them, in the first place.

I do think it also increases steeply the likelihood that military applications are paramount here knowing where BAE places it business focus these days. As it says in the link below BAE are primarily a defence company.

http://www.ibtimes.co.uk/bae-systems-buy-20-stake-reaction-engines-1526711

Now will they be able or wanting to attract other big investors perhaps someone like Airbus?
On reflection what I find interesting is that it is BAE doing this and not Rolls Royce, if it had been the latter then I would have been concerned that they were only interested in having hypersonic engine technology to shop around and had no interest in making a vehicle as they could make a profit just from the engine tachnology but BAE builds aircraft not engines, it makes money from this if Skylon gets built and their investment is structured to put themselves at the head of the que when the work gets handed out.

So BAE believes Skylon is going to be built and that there'll be competition over being part of building it and so this is an investment in having a leg up over other suppliers.
Regarding BAE being a defence company, in fairness they have been trying to diversify, the attempt to merge with EADS was about balancing their defence business with the civil aircraft business of Airbus. Skylon, should it take off, could do that for them.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 11/02/2015 04:51 pm
After reading the press release, it does sound as though BAE are bringing much more to the table than a pile of bank notes. I'd say the odds are now good that they'll have some sort of working SABRE test bed in 2020, which is phenomenal news.

Anyone care to guess what was meant by BAE providing access to 'capital resources'? Perhaps financing in addition to the £20 (or for other aspects of the Skylon project, e.g. airframe/TPS development)? If so, then that's also significant.

Quote
The working partnership will draw on BAE Systems’ extensive aerospace technology development and project management expertise and will provide Reaction Engines with access to critical industrial, technical and capital resources to progress towards the demonstration of a ground based engine
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: aero on 11/02/2015 05:06 pm
After reading the press release, it does sound as though BAE are bringing much more to the table than a pile of bank notes. I'd say the odds are now good that they'll have some sort of working SABRE test bed in 2020, which is phenomenal news.

Anyone care to guess what was meant by BAE providing access to 'capital resources'? Perhaps financing in addition to the £20 (or for other aspects of the Skylon project, e.g. airframe/TPS development)? If so, then that's also significant.

Quote
The working partnership will draw on BAE Systems’ extensive aerospace technology development and project management expertise and will provide Reaction Engines with access to critical industrial, technical and capital resources to progress towards the demonstration of a ground based engine

I would guess "Capital resources" at a minimum is referring to facilities. Maybe a test stand, work shop and office space. Hopefully a little more, like an upgraded test stand with some minimal staff.

Allowing access to unused facilities shouldn't cost BAE a lot but would be a huge help.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 11/02/2015 05:22 pm
BAE has a couple of Skylon renders that may be new on their site. It shows a lighter TPS:

https://resources.baesystems.com/pages/search.php?search=%21collection18040&k=29477be65c&offset=0&order_by=relevance&sort=DESC&thumbs=show&
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: The Amazing Catstronaut on 11/02/2015 05:40 pm
To be fair to BAE, hypersonic aircraft for defense purposes is where the wind is blowing right now; you can understand why they would invest in a company developing enabling propulsion systems for sustained hypersonic flight. Even if it does result in the the technology having a military application, it's not that tragic. It's unlikely a hypersonic jet would ever be used to practically kill people and nearly everything mainstream in civilian aerospace is the result of some kind of military development program.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 11/02/2015 06:34 pm
Anyway, I guess this is a first anwer to who'll be behind the steer in the manufacturer's consortium. This question has kept us discussing for quite a long time. It might not be the answer we wanted (although it seems logical, ex post) but it's an answer to a rather fundamental question and adds lots of credibility to the project.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 11/02/2015 06:49 pm
Someone at BAE must have been listening to me because I suggested on numerous websites that BAE should invest in Reaction Engines. I didn't think BAE were led by people who were still capable of taking bets on future technologies. They seem too busy trying to flog BAE off.

Skylon is also essentially one large drone and BAE has done a lot of work in developing automated drones. Which would be off great help to Reaction Engines further down the line. BAE is involve in work to get drones to be able to fly in civilian airspace.

One of the most important things about this is that a company as well known as BAE is willing to invest in them, in the first place.

I do think it also increases steeply the likelihood that military applications are paramount here knowing where BAE places it business focus these days. As it says in the link below BAE are primarily a defence company.

http://www.ibtimes.co.uk/bae-systems-buy-20-stake-reaction-engines-1526711

Now will they be able or wanting to attract other big investors perhaps someone like Airbus?

 
BAE have said in the past that they want to diversify themselves away from defence, ironic considering it wasn't that long ago that they sold their Airbus stake. Investment in cyber security and battery technology is just two areas they are working towards this. Space was a obvious third pillar they could/should pursue but all the prime assets are already own by large companies who aren't willing to sell, which left BAE Systems only one strategy and that was to take a punt on a future technology.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 11/02/2015 07:11 pm

To be fair to BAE, hypersonic aircraft for defense purposes is where the wind is blowing right now; you can understand why they would invest in a company developing enabling propulsion systems for sustained hypersonic flight. Even if it does result in the the technology having a military application, it's not that tragic. It's unlikely a hypersonic jet would ever be used to practically kill people and nearly everything mainstream in civilian aerospace is the result of some kind of military development program.

Don't be so sure at the benign defence usage in the US the hypersonic element would appear to be seen very much as part of the family systems representing the new global strike capability headed by the Northrop Grumman B-3 or whatever it ends up being called.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alpha_Centauri on 11/02/2015 07:20 pm
BAE won't be interested in this to make a hypersonic bomber, at least not directly themselves. At most the stake is there to prevent control by a rival in a better position to do that.

They will however be very interested in the complex systems integration and avionics, hence the preferred supplier contract. Platforms is more their thing now.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 11/02/2015 08:50 pm

BAE won't be interested in this to make a hypersonic bomber, at least not directly themselves. At most the stake is there to prevent control by a rival in a better position to do that.

They will however be very interested in the complex systems integration and avionics, hence the preferred supplier contract. Platforms is more their thing now.

It wasn't a hypersonic bomber more a high speed reconnaissance craft with some strike capability.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 11/02/2015 10:24 pm
- BAE Systems agree to buy a 20% stake in Reaction Engines Ltd worth £20.6m, which entitles them to a seat on the board and a position as "preferred supplier".

Well that must be the bargain of the century.
Given REL's potential to own a multi billion dollar industry plus it's significantly valuable IP which has wide commercial applications a valuation oding the press release, it does sound as though BAE are bringing much more to the taf 100 million pounds seems a little low.

The obvious conclusion is that no big industry partner believed the odds of REL owning a multi-billion dollar industry were high.  Value equals size of payoff times probability of achieving the payoff.
Sure but compared to some Silicon Valley unicorns REL has a better shot of owning it's market and the book value of its patents is surely more than the valuation put on the company.

You may believe that, but the facts of this deal say that no big aerospace player and no big investor agrees with your assessment, or REL would have gotten a better valuation (and the bigger financial investment they had earlier indicated they wanted).

On reflection what I find interesting is that it is BAE doing this and not Rolls Royce, if it had been the latter then I would have been concerned that they were only interested in having hypersonic engine technology to shop around and had no interest in making a vehicle as they could make a profit just from the engine tachnology but BAE builds aircraft not engines, it makes money from this if Skylon gets built and their investment is structured to put themselves at the head of the que when the work gets handed out.

So BAE believes Skylon is going to be built and that there'll be competition over being part of building it and so this is an investment in having a leg up over other suppliers.
Regarding BAE being a defence company, in fairness they have been trying to diversify, the attempt to merge with EADS was about balancing their defence business with the civil aircraft business of Airbus. Skylon, should it take off, could do that for them.

No, it doesn't indicate BAE believes Skylon is going to be built.  It indicates BAE thinks there is some small chance that REL technology will end up going into something that gets funded, whether it's Skylon or something else.

This is good news for REL -- they get funded to build an engine and test it on the ground.  Celebrate that, don't try to exaggerate it into far more than it actually is.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Eric Hedman on 11/03/2015 01:44 am
BAE buying into Reaction Engines.


http://www.telegraph.co.uk/finance/newsbysector/industry/11967229/Want-to-fly-at-2500mph-BAE-Systems-does-and-is-willing-to-pay-20m-for-it.html (http://www.telegraph.co.uk/finance/newsbysector/industry/11967229/Want-to-fly-at-2500mph-BAE-Systems-does-and-is-willing-to-pay-20m-for-it.html)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/03/2015 07:45 am
BAE buys 20% stake in Reaction Engines

Financial Times story here http://www.ft.com/cms/s/0/a25d2798-7f1b-11e5-98fb-5a6d4728f74e.html

I appreciate most people won't have an FT account, so the main points of the article:
The synopsis is much appreciated.
Quote

- BAE Systems agree to buy a 20% stake in Reaction Engines Ltd worth £20.6m, which entitles them to a seat on the board and a position as "preferred supplier".
That does not sound like much for something that REL have significantly de risked over the last few decades.

As for "preferred supplier" status I'm not sure there's anything BAe can supply that can't be supplied by many other companies.  Key suppliers would be specialist materials and components.

Quote
- The investment in REL will unlock a further £60m grant package from the UK government.
George Osborne offered £60m to REL over the last 2 years. Is this another £60m? If so that's nice but AFAIK that original package had no requirement for REL to get a major investor.
Quote
- However, the group has had to scale back its ambitions for a test engine in order to clinch the funding deal.
So more money, less engine?
Quote
- The group now has "no immediate funding needs".
That's encouraging.
The heat exchanger work miiiiight be applicable to recuperated jet engines, as some of the more advanced ultrahigh bypass ratio turbofan deigns are considering recuperation. Notably MTU, which had a ducted geared counterrotating propfan engine with recuperation (CLAIRE, CRISP, and NEWAC programs). Though that's dealing with turbine exhaust and compressor heat with an all air medium.
REL have stated their HX work has applications to de salination. Highly compact HX's have applications wherever space is a premium, the classic being North Sea oil rigs, which pioneered this kind of stuff, using diffusion bonded plates to create HX's about 1/3 the size based on conventional fluid flow principles. REL's are (IIRC) about 1/2 that size.

One of the most important things about this is that a company as well known as BAE is willing to invest in them, in the first place.
And no doubt BAe told them they were doing them a favor in doing so.  :(

I wondered if they played the "We have guaranteed access to the Prime Minister because we're 'British'" card as well?
Quote
I do think it also increases steeply the likelihood that military applications are paramount here knowing where BAE places it business focus these days. As it says in the link below BAE are primarily a defence company.
Yes, that seat on the board may well cause a fairly corrosive change in viewpoint.

The real problem with their being a defense contractor is their mindset. They are very bad at the concept of selling to something that's not a government and not doing a cost plus contract. Like LM they had a commercial airplane mfg arm but sold it off decades ago.

For a business plan built on the idea of selling to the whole world that's not view point to have.
Quote
Now will they be able or wanting to attract other big investors perhaps someone like Airbus?
Strictly for this it's the banks behind airbus, as it was the banks behind TML, who built the Channel Tunnel, or the banks behind EuroTunnel, who operate it.

Note however that this still depends on a vote from the stockholders.
You may believe that, but the facts of this deal say that no big aerospace player and no big investor agrees with your assessment, or REL would have gotten a better valuation (and the bigger financial investment they had earlier indicated they wanted).
Or perhaps REL's engineering skills exceed their talents for self promotion and negotiation? Not unknown in UK engineering businesses.

I'm sure we can come up with a few other scenarios as well.
Quote
No, it doesn't indicate BAE believes Skylon is going to be built.  It indicates BAE thinks there is some small chance that REL technology will end up going into something that gets funded, whether it's Skylon or something else.
Which no one knows about (or has even designed) but that BAe wants a part of?

Aurora II ?  :)

Only I'm not sure that "preferred supplier" status would carry over onto another project.

Historically very bad things happen to pricing when a key supplier has a monopoly position. I'm thinking of when Orbital went with Hercules for the solids on the Pegaus and the price doubled
Quote
This is good news for REL -- they get funded to build an engine and test it on the ground.  Celebrate that, don't try to exaggerate it into far more than it actually is.
How thoughtful of you to help curb any unseemly displays of enthusiasm.

Indeed let's see how their development programme works out over the next 5 years compared to other player.
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 11/03/2015 08:46 am
It wouldn't surprise me if BAE want their technology for two reasons. One the obvious ones of commercial opportunities in the space realm. Two & perhaps more immediate that a contract has come up in the black world that they think this technology will put them in a good place to bid for a slice of the action.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 11/03/2015 12:54 pm
The Financial Times article also mentions that REL have been talking to other industrial partners about joining the project.

So don't hold your breath but this may not be the last such deal.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: momerathe on 11/03/2015 01:30 pm
I'm just glad to see some forward momentum. If the ground test is successful it will persuade some people off the fence, I'm sure.

On a personal note, though, that 5 years is going to be an agonising wait! With any luck some of the BAE PR people will throw us a bone with a bit more regularity ;).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Ravenger on 11/03/2015 03:44 pm
BAE has a couple of Skylon renders that may be new on their site. It shows a lighter TPS:

https://resources.baesystems.com/pages/search.php?search=%21collection18040&k=29477be65c&offset=0&order_by=relevance&sort=DESC&thumbs=show&

I love the white Skylon images - looks like the child of SR71 and Concorde. Simply beautiful  :D

I need a model of the D1 version in that colour scheme to go with my C1 model (which was signed by Alan Bond).

 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 11/03/2015 06:00 pm
I'm just glad to see some forward momentum. If the ground test is successful it will persuade some people off the fence, I'm sure.

On a personal note, though, that 5 years is going to be an agonising wait! With any luck some of the BAE PR people will throw us a bone with a bit more regularity ;).

Yeah, 5 years is a long time.  It's not just us having to wait.  Every year that goes hurts REL's chances for Skylon being funded because other players in the launch industry move forward.  If in 5 years SpaceX is regularly launching payloads to orbit on reused first stages, that really cuts badly into the value proposition for Skylon, even if everything goes perfectly with the Sabre engine on the test stand.  The lower the cost of other launch options, the harder it is to make the case for Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: TrevorMonty on 11/03/2015 06:45 pm
I'm just glad to see some forward momentum. If the ground test is successful it will persuade some people off the fence, I'm sure.

On a personal note, though, that 5 years is going to be an agonising wait! With any luck some of the BAE PR people will throw us a bone with a bit more regularity ;).

Yeah, 5 years is a long time.  It's not just us having to wait.  Every year that goes hurts REL's chances for Skylon being funded because other players in the launch industry move forward.  If in 5 years SpaceX is regularly launching payloads to orbit on reused first stages, that really cuts badly into the value proposition for Skylon, even if everything goes perfectly with the Sabre engine on the test stand.  The lower the cost of other launch options, the harder it is to make the case for Skylon.
If SpaceX can increase the demand for spaceflight by lowering costs with reusability, that only improves Skylon's chances of being developed.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 11/03/2015 06:48 pm
I'm just glad to see some forward momentum. If the ground test is successful it will persuade some people off the fence, I'm sure.

On a personal note, though, that 5 years is going to be an agonising wait! With any luck some of the BAE PR people will throw us a bone with a bit more regularity ;).

Yeah, 5 years is a long time.  It's not just us having to wait.  Every year that goes hurts REL's chances for Skylon being funded because other players in the launch industry move forward.  If in 5 years SpaceX is regularly launching payloads to orbit on reused first stages, that really cuts badly into the value proposition for Skylon, even if everything goes perfectly with the Sabre engine on the test stand.  The lower the cost of other launch options, the harder it is to make the case for Skylon.
If SpaceX can increase the demand for spaceflight by lowering costs with reusability, that only improves Skylon's chances of being developed.

Not if in the process SpaceX's costs go below those projected for Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: momerathe on 11/03/2015 08:14 pm
Not if in the process SpaceX's costs go below those projected for Skylon.

Welp, the long game is cheap access to space - I don't care who does it. I personally have my doubts about just how low SpaceX can go, but I wish them luck. If they manage it, great! if they don't, maybe Skylon will.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 11/03/2015 08:30 pm
I'd imagine that Skylon's launch prices would depend strongly on flight rate - probably more strongly than SpaceX's, since the system is fully reusable with a relatively high DDT&E cost and potentially very low processing overhead.  The current projection of $20M per flight is ten times the lowest number they've ever produced, which was for low-value cargo in an arbitrarily large market.

There are other advantages as well, such as the Shuttle-like on-orbit ops and downmass capabilities (without adding cost and reducing payload mass and volume by adding a capsule) and the very high projected reliability.  It's not really an apples-to-apples comparison, and even if SpaceX comes out cheaper, price may not be the only relevant market factor.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Kansan52 on 11/03/2015 08:55 pm
"...and even if SpaceX comes out cheaper, price may not be the only relevant market factor."

Totally agree.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: TrevorMonty on 11/03/2015 09:02 pm
The one payload Skylon would be good for is delivering fuel. Especially if they can hit $1000kg mark as per their website. There are no fuel depots at present, but ULA and their distributed launch system offers hope here.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 11/03/2015 09:53 pm
I'd imagine that Skylon's launch prices would depend strongly on flight rate - probably more strongly than SpaceX's, since the system is fully reusable with a relatively high DDT&E cost and potentially very low processing overhead.

Yeah, Skylon's very high development costs make its economics highly dependent on flight rate.

The current projection of $20M per flight is ten times the lowest number they've ever produced, which was for low-value cargo in an arbitrarily large market.

There are other advantages as well, such as the Shuttle-like on-orbit ops and downmass capabilities (without adding cost and reducing payload mass and volume by adding a capsule) and the very high projected reliability.  It's not really an apples-to-apples comparison, and even if SpaceX comes out cheaper, price may not be the only relevant market factor.

In terms of downmass, I agree Skylon might have an advantage.  It's not clear how much that will count in the market.  STS never carried much downmass, though things might change in the future and with much lower costs to orbit.

The "very high projected reliability" part, though, I completely disagree with.  There's no reason to actually think Skylon would have better reliability.  It's a paper rocket at this point, and no detailed design has been done, so there's little to go on for projecting reliability, but historically liquid hydrogen systems haven't been as reliable as systems using other sorts of fuel.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 11/04/2015 01:49 am
Ummm... Development costs are sunk costs and so have no impact whatsoever on the operational economics.
Flight rate is important if you have high (operational) fixed costs like a standing army of engineers for maintenance, support infrastructure that needs to be operated and so on.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 11/04/2015 01:54 am
Ummm... Development costs are sunk costs and so have no impact whatsoever on the operational economics.
Flight rate is important if you have high (operational) fixed costs like a standing army of engineers for maintenance, support infrastructure that needs to be operated and so on.

No.  Development costs only become sunk costs after the money has been spent.

If at some point in the future the development has been completed, then we can consider development costs sunk and ignore them for purposes of determining business model feasibility.

Right now, they are absolutely not sunk costs.  They must be included in any analysis of the economic case for Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 11/04/2015 02:30 am
There's no reason to actually think Skylon would have better reliability.

Sure there is.  It's the nature of the vehicle we're talking about, not the bolt supplier's testing practices.  You don't get multiple orders of magnitude on your loss-of-vehicle numbers by fiddling with the design details.

Skylon is more of an airplane than a rocket.  It takes off and flies like an airplane, which allows it to have full intact abort capability (including engine out) with no black zones.  It lands like an airplane (well, like a glider), which is a comfortable, well-understood maneuver (particularly for a computer) and doesn't put a main engine relight on the critical path with no time to troubleshoot if it doesn't work.  It is intended to be certified like an airplane, with an extensive test programme putting two prototypes through hundreds of flights including dozens of abort tests, and each production unit will undergo four test flights before delivery.  It is also an SSTO, which means that if staging (a major launch risk) is required at all, it can be done at a leisurely pace after the launch, as more of a payload deployment than a controlled inflight breakup.  And of course it's fully reusable, which means infant mortality should be way down.

As of March 2014, REL was targeting a 1% abort rate (similar to the loss rate for some of the better ELVs) and a 0.005% loss rate per mission, and based on earlier comments by Mark Hempsell they expect both those metrics to be much better in actual operation.  In other words, those are more like must-not-exceed numbers than optimistic projections.

Quote
historically liquid hydrogen systems haven't been as reliable as systems using other sorts of fuel.

Centaur
Saturn V
DC-X
Ariane 5
Delta IV
STS
...

I don't see the problem, unless you're talking about niggling intermittent launch-delaying issues like the Shuttle's GUCP troubles or the Delta IV's sticky fuel valves, which aren't really the sort of thing I was talking about.  Even those should be greatly mitigated by the extensive flight test programme (so systematic design and maintenance issues can be worked out) and by the highly reusable nature of the whole system (so you don't have untried factory fresh parts on every launch).

Based on what we know of the engine, they seem to have circumvented the main issues with the SSME that made it dangerous and maintenance-intensive.  (Even so, note that Falcon 9 has already had more catastrophic engine failures than STS...)

Ummm... Development costs are sunk costs and so have no impact whatsoever on the operational economics.

They affect launch prices (not costs), because they affect the purchase price of the vehicles.  Skylon doesn't have thousands of years to pay back its development costs; there's a finite horizon within which you have to confine your economic analysis, and the development cost looms large in that context.

Even as matters stand, the numbers they're talking about seem pretty competitive.  The more SpaceX expands the market, the more likely it becomes that Skylon will undercut them.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 11/04/2015 02:37 am
Development cost of course has to be taken into account NOW because now you do of course want your investment case to close.
And yes, of course you have to make sure you have a decent assumption on the flight rate.
But in case that assumption turns out overly optimistic at some point in the future after you convinced someone to pay for the development Skylon - at least the ones built - could still be profitable at a lower flight rate if operating costs are low.
Even the sales price will drop, you have big write offs, your investors lose their money but the ongoing project could still be profitable.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 11/04/2015 02:57 am
That's true, I guess - it could turn out like Iridium, or Concorde.  I hope it doesn't - depending on the circumstances, it might imply that the market isn't as robust as we would like, and it would certainly deter future investment into similar systems (see Concorde), but at least the fallback does seem to exist for a system this development-heavy.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 11/04/2015 03:11 am
Yea, but Iridium and Concorde were not doomed due to excessive development costs. Concord had excessive operating costs (it was still lossy after they wrote down all of the purchase costs) and Iridium was simply the wrong product for the market.
Eurotunnel would be a better example. Way over cost, investors lost most of their money but the whole thing is now highly profitable after writing off the initial investment.

The problem with a system like Skylon is that your actual market better be as predicted because otherwise you can't afford ongoing development and a system that doesn't see ongoing development will be dead at some point. But at least you can recover from excessive initial dev costs and you are not dependent on being able to up flight rates to recover excessive development spending or something like that.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 11/04/2015 03:23 am
Concord had excessive operating costs (it was still lossy after they wrote down all of the purchase costs)

That's not how I heard it.  As I understand it, British Airways consistently turned a profit on it, and Air France's service was spottier but not exactly a loss leader.  Things went to pot after the crash (9/11 didn't help, nor did the recession, and they were looking at increasing maintenance issues anyway), but prior to that the vehicle seems to have been useful enough on its main routes to make up for the high operating costs.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 11/04/2015 03:40 am
There's no reason to actually think Skylon would have better reliability.

Sure there is.  It's the nature of the vehicle we're talking about, not the bolt supplier's testing practices.  You don't get multiple orders of magnitude on your loss-of-vehicle numbers by fiddling with the design details.

The Space Shuttle was supposed to be orders of magnitude safer than previous vehicles too.  Its projected reliability was far, far greater than what it turned out to be in practice.

The point is with a new design that is very different from existing systems you usually don't know what will be the real reliability problems.  It's just too early in the process.  And the designers of these vehicles are always sure they will be much much safer.  But it's all nonsense.

Skylon is more of an airplane than a rocket.

People tend to think that.  It's human nature.  What does it look like that I understand?  OK, so it must behave like that.

But it's not always so.  We can look deeper and see if it really holds.

Skylon is supposed to go to orbit.  It uses airplane-like takeoff and generates lift like an airplane for part of its flight.  But it does other things that are not at all like any airplane we have experience with.  Its engines are supposed to be both air-breathing and rockets at different points in flight.  It's supposed to use liquid hydrogen and liquid oxygen.  It's supposed to go to Mach 25.  It's supposed to re-enter from Mach 25.  All very much unlike all the airplanes we have experience with.  It is all those things that give it much more risk than a typical airplane.

It takes off and flies like an airplane, which allows it to have full intact abort capability (including engine out) with no black zones.

It only has an abort capability for certain kinds of failures, not all the kinds of failures a more traditional launch vehicle with an abort system has.  For example, if Falcon 9 has an engine that is about to explode and destroy the main propellant tank, the Dragon abort system can pull the capsule away from the exploding main tanks.  Skylon can't do that.  If the Skylon main prop tanks are about to explode, nothing at all can be done.

And Falcon 9/Dragon has no black zones in its abort capability either.  It's not an "intact" abort in the sense that the first and second stages are possibly lost, but that's a positive, not a negative, because it allows the people to escape and survive when the engines and prop tanks explode.

It lands like an airplane (well, like a glider), which is a comfortable, well-understood maneuver (particularly for a computer)

The computers doing a Dragon propulsive landing are just as "comfortable" with that landing maneuver.

Propulsive landings can be done anywhere there's a small flat area, not just on a runway.  They're much more flexible that way.  If Skylon loses propulsion, it has to get back to a runway, which isn't easy as it has a poorer glide ratio than a typical airplane, and even a typical airplane will often have trouble getting back to its runway to land if engines are lost at the wrong time (see the airliner that landed on the Hudson a few years ago).

Also, propulsive landings give more than one shot at an approach.  With a glider, if there's a sudden gust of wind and conditions aren't good, you still have to land.  In a powered airplane, there's the option to throttle up and go around, and airplanes use that option not too infrequently.  Gliders don't have the choice.  A Dragon doing a propulsive landing has the choice.  If there's a momentary gust of wind, it can throttle up, go up in the air, then settle back down again.

and doesn't put a main engine relight on the critical path with no time to troubleshoot if it doesn't work.

Dragon can land even if any one engine fails to light, and it has a backup parachute landing system.  So, even if the engines fail to light, it can still land safely.  Skylon has no backup -- it has to glide to a landing or it crashes disastrously.

It is intended to be certified like an airplane, with an extensive test programme putting two prototypes through hundreds of flights including dozens of abort tests,

And Dragon can do exactly the same thing.

and each production unit will undergo four test flights before delivery.

Dragon can do exactly the same.

It is also an SSTO, which means that it can wait out bad weather on orbit or divert to almost anywhere in the world (the wings afford a very large cross range),

That has absolutely nothing to do with it being SSTO!  That has to do with how much lift it generates.  Shuttle and Dream Chaser are not SSTO but they can also generate lots of lift on re-entry and get lots of cross-range.

Dragon can also wait out bad weather on orbit.  It doesn't need much cross-range capability to do that.  And Dragon can land in far more places than Skylon, so it actually has more flexibility there.

and that if staging (a major launch risk) is required at all, it can be done at a leisurely pace after the launch, as more of a payload deployment than a controlled inflight breakup.

Staging of Falcon 9 is in no meaningful way like an "inflight breakup".  That's just a meaningless emotional argument about superficial similarity with no substance to it.

And of course it's fully reusable, which means infant mortality should be way down.

SpaceX is closing in on reusability of both their first stage and Dragon.  Both are designed for it.  SpaceX has also said they plan to eventually have a reusable second stage, though they're not pursuing that at the moment.  But you can bet that if the flight rate is high enough to make it make economic sense SpaceX will create a reusable upper stage.  The cost for SpaceX to create a reusable upper stage should be far, far less than the cost to develop Skylon, so the advantage is to SpaceX on the reusability front.

As of March 2014, REL was targeting a 1% abort rate and a 0.005% loss rate per mission, and based on earlier comments by Mark Hempsell they expect both those metrics to be much better in actual operation.

What they're targeting is irrelevant.  Shuttle was supposed to have much higher reliability than it actually had.  Vehicle designers always have rosier projections than the way things turn out in practice.  Mark Hempsell and the rest of the REL team don't actually have experience designing a vehicle and seeing it through to an operational launch system.  The REL team has a lot of experience doing research on engine components and writing slideware, not much on systems that actually become operational.

In other words, those are more like must-not-exceed numbers than optimistic projections.

But there's no way they could possibly know the real reliability.  They are of course optimistic projections not grounded in any evidence.

Quote
historically liquid hydrogen systems haven't been as reliable as systems using other sorts of fuel.

Centaur
Saturn V
DC-X
Ariane 5
Delta IV
STS
...

I don't see the problem,

STS killed more astronauts than any other space launch system in history.  And it's an instructive lesson because at the time it was conceived, it was seen by its designers very much as Skylon is seen by its designers -- a radically different design, reusable, and the solution to make space launch much safer and cheaper than ever before.

STS's problems came from trying to push the edge of what is possible -- exactly what Skylon hopes to do.

unless you're talking about niggling intermittent launch-delaying issues like the Shuttle's GUCP troubles or the Delta IV's sticky fuel valves, which aren't really the sort of thing I was talking about.

Those sorts of things make the systems much more expensive.

Even those should be greatly mitigated by the extensive flight test programme (so systematic design and maintenance issues can be worked out) and by the highly reusable nature of the whole system (so you don't have untried factory fresh parts on every launch).

Falcon/Dragon has all those advantages too, but without the disadvantages of having to use liquid hydrogen (very low temperatures and hydrogen working its way into everything, causing leaks and embrittlement) and the disadvantages of having to be single-stage to orbit (so there is less margin available for safety).

Based on what we know of the engine, they seem to have circumvented the main issues with the SSME that made it dangerous and maintenance-intensive.

It's premature to make pronouncements about an engine that hasn't been built yet.

(Even so, note that Falcon 9 has already had more catastrophic engine failures than STS...)

No.  Falcon 9 has had zero catastrophic engine failures.  It has had one catastrophic structural failure.  It's not a catastrophic failure if the vehicle keeps flying and makes orbit.

STS had one catastrophic engine failure -- of a solid engine.

Ummm... Development costs are sunk costs and so have no impact whatsoever on the operational economics.

They affect launch prices (not costs),

No, they affect costs.  Development costs are costs.  The word "cost" doesn't just apply to operational costs.

The price a company charges isn't necessarily directly related to the costs.  It often has more to do with the market -- what the market will bear.

because they affect the purchase price of the vehicles.  Skylon doesn't have thousands of years to pay back its development costs; there's a finite horizon within which you have to confine your economic analysis, and the development cost looms large in that context.

Even as matters stand, the numbers they're talking about seem pretty competitive.  The more SpaceX expands the market, the more likely it becomes that Skylon will undercut them.

I don't see any evidence for that.  An expanding market allows SpaceX to lower prices too because its per-flight costs go down when volume goes up too.

In addition to Skylon's much higher development costs, there are two factors that argue for it having higher per-flight operational costs: the fact that it uses liquid hydrogen (look at Delta IV's costs versus Atlas V) and the fact that it is single-stage (so it has less mass margin to use making things more rugged and cheaper to maintain).

That doesn't guarantee Skylon's costs will be higher, but it suggests they are likely to be.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 11/04/2015 03:50 am
I'll get back to this later.  I can't spend the time now.  For now I'll just say that from a quick read-through, it seems you're going to great lengths to miss the point of several of my arguments, and making analogies that don't really hold if you inspect them.

And no one said anything about Dragon.  This is a launch vehicle comparison.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/04/2015 06:30 am
The one payload Skylon would be good for is delivering fuel. Especially if they can hit $1000kg mark as per their website. There are no fuel depots at present, but ULA and their distributed launch system offers hope here.
Skylon was designed to be a general purpose transporter. It's core mission is sending comm sats to GTO.

Much lower price per Kg is a key enabler of many missions but where Skylon shines here is downmass

Quite a lot of countries can put stuff into space but only 3 (Russia, SX and ESA) can get it down.

That becomes very important if you want to carry people into space as for the foreseeable future they will also want to come back.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/04/2015 07:08 am
Yeah, Skylon's very high development costs make its economics highly dependent on flight rate.
No it's development cost, on a par with a similarly sized reusable aircraft, are highly dependent on it's mfg being able to sell enough of them .

It's customers economics depend on their flight rate, which depends on their business model.
Quote
In terms of downmass, I agree Skylon might have an advantage.  It's not clear how much that will count in the market.  STS never carried much downmass, though things might change in the future and with much lower costs to orbit.
How about the 7 astronauts it carried on pretty much every flight?
Quote
The "very high projected reliability" part, though, I completely disagree with.  There's no reason to actually think Skylon would have better reliability.  It's a paper rocket at this point, and no detailed design has been done, so there's little to go on for projecting reliability,
Perhaps you'd like to walk us through your logic on this. Most open minded people would say the reverse.
Quote
but historically liquid hydrogen systems haven't been as reliable as systems using other sorts of fuel.
There's a difference between developing an LH2 engine and operating it.

LH2 engines have been more difficult to develop but once in service have performed  as well as LOX/Kero or storable engines in terms of reliability.

Perhaps you could list some specific LH2 engine failures you have in mind? SSME has never failed in flight operation, the first Ariane 5 was a GNC fault and AFAIK the original J2 never had trouble starting when attached to a vehicle.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: momerathe on 11/04/2015 07:30 am
Do we really have to go over this again? is there anything that hasn't been said a hundred times before in these threads?

I for one would rather concentrate on the news, not rehashing old arguments.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 11/04/2015 10:12 am
I'd imagine that Skylon's launch prices would depend strongly on flight rate - probably more strongly than SpaceX's, since the system is fully reusable with a relatively high DDT&E cost and potentially very low processing overhead.  The current projection of $20M per flight is ten times the lowest number they've ever produced, which was for low-value cargo in an arbitrarily large market.

There are other advantages as well, such as the Shuttle-like on-orbit ops and downmass capabilities (without adding cost and reducing payload mass and volume by adding a capsule) and the very high projected reliability.  It's not really an apples-to-apples comparison, and even if SpaceX comes out cheaper, price may not be the only relevant market factor.

A fundamental issue, both for SpaceX_R and Skylon launch costs, is the pricing of the competitors. To decrease actual costs to space you need at least two companies with reusable vehicles: one will not do the trick: if only one company reaches reusability, it will just set the price an inche below the competitor's best price and get all the market it can.
A second company is needed to get the competition you want: in a market environment, technology alone does not drive costs down. tech*companies does.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 11/04/2015 10:14 am
I'd imagine that Skylon's launch prices would depend strongly on flight rate - probably more strongly than SpaceX's, since the system is fully reusable with a relatively high DDT&E cost and potentially very low processing overhead.

Yeah, Skylon's very high development costs make its economics highly dependent on flight rate.


only for a private operator. a public operator would still enjoy very low costs and have the infrastructure ready when it needs so (eventually) in the future.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 11/04/2015 01:24 pm
It lands like an airplane (well, like a glider), which is a comfortable, well-understood maneuver (particularly for a computer)

Can you explain the reasoning behind this comment? Chris was discussing "reliability" and abort scenarios. I'm not aware of any mainstream autopilot system that is capable of even an unpiloted emergency landing after a single engine-out, let alone an all-engines-out emergency glide.

I suspect bleeding-edge automation is pretty close, but it's certainly not something that can be called "comfortable, well-understood". And the decisions in a true emergency landing, ie when an airport is too far away, is beyond even those experimental systems.

Quote
historically liquid hydrogen systems haven't been as reliable as systems using other sorts of fuel.
Centaur      Expendable
Saturn V     Expendable
DC-X          Suborbital experiment
Ariane 5      Expendable
Delta IV      Expendable
STS           Expendable hydrogen tank, very expensive and high-maintenance engine.
...

Not sure what this list tells you about the reliability of reusable hydrogen rockets.

Dragon can also wait out bad weather on orbit.  It doesn't need much cross-range capability to do that.

Skylon can also wait in orbit before re-entering. Plus Skylon can fly around weather during launch, and fly to launch windows after a delay, making it much more responsive to customers. Fuel use during the subsonic jet-coast phase will be trivial. (A fully loaded 777 will only burn a tonne of fuel every 5hrs or so, for example.)

In a powered airplane, there's the option to throttle up and go around, and airplanes use that option not too infrequently.  Gliders don't have the choice.  A Dragon doing a propulsive landing has the choice.  If there's a momentary gust of wind, it can throttle up, go up in the air, then settle back down again.

I haven't heard, and don't believe, that Dragon has such a capability. It's a high commitment landing system. Do you have any references that suggest otherwise?

I agree that advocates are grossly underplaying Skylon's complexity and risks, but exaggerating in the other direction isn't the answer.
Title: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 11/04/2015 06:51 pm
Concord had excessive operating costs (it was still lossy after they wrote down all of the purchase costs)

That's not how I heard it.  As I understand it, British Airways consistently turned a profit on it, and Air France's service was spottier but not exactly a loss leader.  Things went to pot after the crash (9/11 didn't help, nor did the recession, and they were looking at increasing maintenance issues anyway), but prior to that the vehicle seems to have been useful enough on its main routes to make up for the high operating costs.

Fromm what I heard the New York route was the only one it was ever profitable and only at these very low flight rates. Plus a few high-value charters. But that was essentially the whole market. Which was what doomed it.

I mean... I think in the end they didn't even fly the whole fleet anymore
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/04/2015 09:07 pm
A fundamental issue, both for SpaceX_R and Skylon launch costs, is the pricing of the competitors. To decrease actual costs to space you need at least two companies with reusable vehicles: one will not do the trick: if only one company reaches reusability, it will just set the price an inche below the competitor's best price and get all the market it can.
A second company is needed to get the competition you want: in a market environment, technology alone does not drive costs down. tech*companies does.
Keep in mind that in principle Skylon creates its own competitors as multiple copies are sold. Logically some will be retained for the exclusive use of national governments. Some will be purchased to supply launch services for 3rd party clients. All work toward covering the DDT&E costs of the project regardless of how many payloads each actually launches.

This is a step change in the way LV's are built and designed.

As more are sold Skylon becomes less unique and pricing strategies will change in ways that simply don't happen where the there is only one operator (who is essentially the manufacturer) of the vehicle.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/04/2015 10:20 pm
Automated landing has a long history.

AFAIK the first versions were the X10 test vehicle for the Navajho missile program

https://en.wikipedia.org/wiki/North_American_X-10

Autoland for commercial (passenger carrying) aircraft under Catagory 3b (dense fog) were being done by the mid 1960's. This was delayed in the US as bad visibility normally comes with wind shear, which the systems did not cope with well. [EDIT and which was not a problem for most of the runways that the British operated out of and needed autoland for ]

Regarding glide landings the Shuttle demonstrated 134 landings and NASA developed procedures (essentially a long, thick cable) to let the GPC's deploy the landing gear and fire the parachute (both irreversible events that were felt to need pilot control). The autoland logic had been in the code since around flight 3.

Most recently the X37b has demonstrated 3 flights with autonomous glide landing, the last after close to 2 years on orbit.

Skylon has radically better aerodynamics and mass distribution than the Shuttle and REL have stated it is designed to cope with a standard 25Kn cross wind. This still leaves wind shear as a possible issue.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Asteroza on 11/04/2015 11:06 pm
Buran can arguably be the first orbital reentry autoland (first try too! :) )(only try :'()
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/05/2015 08:26 am
Buran can arguably be the first orbital reentry autoland (first try too! :) )(only try :'()
Oops, forgot about them. Also AFAIK a glider and no human intervention. I think you're right they would have been the earliest vehicle as well.

Yes, an excellent point. I wish I knew what their landing condition requirements were though.

Being Russian I would expect them to be fairly "robust" (IE short of gale force)  :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alpha_Centauri on 11/05/2015 12:13 pm
Well Buran means Snowstorm. Perhaps that was literal, as in "can land in a snowstorm"...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/05/2015 04:58 pm
Just a thought.

The last IAC update suggests they are pretty much going for SABRE 4 and I'm fairly sure some of the trajectory analysis in terms of global range has not been mentioned before, although wheather it has been recently done or unknown for years inside the company is another matter.

Time to revise the Skylon User Manual perhaps?

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 11/05/2015 05:03 pm
Anyone know of any upcoming talks from REL? Maybe we might get some more concrete information on SABRE 4 and the engine development plan in general for construction of the ground model etc. Has BAE's involvement changed the road-map ahead in any way?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 11/05/2015 05:20 pm
Anyone know of any upcoming talks from REL? Maybe we might get some more concrete information on SABRE 4 and the engine development plan in general for construction of the ground model etc. Has BAE's involvement changed the road-map ahead in any way?

Well there's one on the 11th. I posted about it a while ago

http://aerosociety.com/Events/Event-List/2172/The-Skylon-Spaceplane-and-Sabre-Engine-Progress-to-Date-and-Future-Prospects

, theres also one  on March 8th.

http://www.jbollerhead.webspace.virginmedia.com/programme.html
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/05/2015 08:34 pm

Well there's one on the 11th. I posted about it a while ago

http://aerosociety.com/Events/Event-List/2172/The-Skylon-Spaceplane-and-Sabre-Engine-Progress-to-Date-and-Future-Prospects
This lecture will be given by one of the control systems engineers of REL. This specialty would be particularly relevant to either the control system of SABRE and the wider control system problem of Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: simonbp on 11/06/2015 03:21 am
So, I was watching this interview on CNN and the image below popped up. What is this?

http://www.cnn.com/videos/business/2015/11/04/bae-systems-reaction-engines-mark-thomas-intv-qmb.cnn
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: banjo on 11/06/2015 04:30 am
i think it is an alternative rendering of skylon produced by university of Strathclyde engineering students.  why cnn are showing it, i dont know.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 11/06/2015 07:15 am
Yes, it's the CFASTT-1 design concept. And it's a good guess that CNN just went through the BAe announcement site and chose that image because it looks the coolest:

https://resources.baesystems.com/pages/search.php?search=%21collection18040&k=29477be65c&offset=0&order_by=relevance&sort=DESC&thumbs=show&

CFASTT-1 info here:

http://strathprints.strath.ac.uk/41933/1/Brown_et_al_Towards_Robust_Aero_Thermodynamic_Predictions_for_Re_Usable_Single_Stage_to_Orbit_Vehicles.pdf
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/06/2015 07:31 am
So, I was watching this interview on CNN and the image below popped up. What is this?

http://www.cnn.com/videos/business/2015/11/04/bae-systems-reaction-engines-mark-thomas-intv-qmb.cnn
Interesting but a bit disturbing.

On the upside. This is a studio interview with the CEO on CNN, which is quite a step up in some ways from REL's media involvement in the past.

On the downside the emphasis on a passenger transport. The REL concept for the LAPCAT II programme is very different to Skylon.

The question is can REL turn this increase exposure into either increased funding or move them forward in forming the Skylon consortium?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 11/06/2015 12:31 pm

So, I was watching this interview on CNN and the image below popped up. What is this?

http://www.cnn.com/videos/business/2015/11/04/bae-systems-reaction-engines-mark-thomas-intv-qmb.cnn
Interesting but a bit disturbing.

On the upside. This is a studio interview with the CEO on CNN, which is quite a step up in some ways from REL's media involvement in the past.

On the downside the emphasis on a passenger transport. The REL concept for the LAPCAT II programme is very different to Skylon.

The question is can REL turn this increase exposure into either increased funding or move them forward in forming the Skylon consortium?

Maybe they will have to do aircraft first & then space vehicles, especially they may go this way with BAE onboard.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 11/06/2015 12:38 pm

So, I was watching this interview on CNN and the image below popped up. What is this?

http://www.cnn.com/videos/business/2015/11/04/bae-systems-reaction-engines-mark-thomas-intv-qmb.cnn
Interesting but a bit disturbing.

On the upside. This is a studio interview with the CEO on CNN, which is quite a step up in some ways from REL's media involvement in the past.

On the downside the emphasis on a passenger transport. The REL concept for the LAPCAT II programme is very different to Skylon.

The question is can REL turn this increase exposure into either increased funding or move them forward in forming the Skylon consortium?

Maybe they will have to do aircraft first & then space vehicles, especially they may go this way with BAE onboard.
Except that's technically much, much harder. A SABRE engine only has to last 100 hours or so with a small fraction of that spent  hypersonic air breathing, a Scimitar engine would spend hours in hypersonic cruise and need to have a lifetime orders of magnitude larger.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: simonbp on 11/06/2015 01:27 pm
No, the interviewer was harping on about the intercontinental transport, while the guy from REL clearly said their focus was on orbital in "10-15 years" and intercontinental in "about 20 years".
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: topsphere on 11/06/2015 02:05 pm
Anyone know of any upcoming talks from REL? Maybe we might get some more concrete information on SABRE 4 and the engine development plan in general for construction of the ground model etc. Has BAE's involvement changed the road-map ahead in any way?

Mark Thomas and Simon Feast are both speaking at the Reinventing Space Conference next Tuesday and Wednesday in Oxford...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hanelyp on 11/06/2015 04:37 pm
So, I was watching this interview on CNN and the image below popped up. What is this?

http://www.cnn.com/videos/business/2015/11/04/bae-systems-reaction-engines-mark-thomas-intv-qmb.cnn
That concept looks like someone took an X-30 style scramjet with forebody integrated inlet and aftbody integrated exhaust nozzle, stripped out the scramjet engines the underbody was designed to serve, and stuck sabre engines on wingtips.  I'm thinking with that fuselage shape you might do better with the sabre engines installed center-body where the scramjets would be, using the contoured underbody for inlet and exhaust.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 11/06/2015 04:55 pm
So, I was watching this interview on CNN and the image below popped up. What is this?

http://www.cnn.com/videos/business/2015/11/04/bae-systems-reaction-engines-mark-thomas-intv-qmb.cnn
That concept looks like someone took an X-30 style scramjet with forebody integrated inlet and aftbody integrated exhaust nozzle, stripped out the scramjet engines the underbody was designed to serve, and stuck sabre engines on wingtips.  I'm thinking with that fuselage shape you might do better with the sabre engines installed center-body where the scramjets would be, using the contoured underbody for inlet and exhaust.

It may look that way, but it's not just an artists' impression or derived from an X-30 style scramjet design. It's the result of an aerothermal study of Skylon:

http://strathprints.strath.ac.uk/41933/1/Brown_et_al_Towards_Robust_Aero_Thermodynamic_Predictions_for_Re_Usable_Single_Stage_to_Orbit_Vehicles.pdf
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 11/06/2015 11:22 pm
The question is can REL turn this increase exposure into either increased funding or move them forward in forming the Skylon consortium?

REL said that with the involvement of BAe, the group now has "no immediate funding needs". Does this mean they are not looking for funding? Does BAe involvement effectively block any more investment anyway since they are now prepared to handle everything up to at least working test engine?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alpha_Centauri on 11/07/2015 12:52 am
Can't see a Skylon airframer committing until there is a representative demonstration of the SABRE cycle, REL doesn't have an actual product to offer them until then.  Right now the focus will be on that, which is what the tie-up with BAE should hopefully deliver.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Dalhousie on 11/07/2015 08:44 am
No, the interviewer was harping on about the intercontinental transport, while the guy from REL clearly said their focus was on orbital in "10-15 years" and intercontinental in "about 20 years".

The media almost always seem focus on LAPCAT rather than Skylon.  Hypersonic transport has a higher public profile than just another space launcher.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alpha_Centauri on 11/07/2015 09:09 am
A little bit more in here about there not necessarily being change in direction vis-a-vis skylon,

http://fortune.com/2015/11/06/bae-commercial-space-launch/

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And for BAE, it offers a critical toehold in the growing space access market. While BAE’s North American arm does a fair amount of business in satellite components and the like, the company has no significant presence in the commercial space launch industry. “It’s a market we’re interested in but we were looking for a different way of doing it,” Allam says. “We were looking for a breakthrough or something new as opposed to just joining everybody else.”

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And what about that super-high-speed point-to-point passenger travel—four hours from anywhere to anywhere on the globe? It’s certainly possible with this kind of technology, Reaction’s Thomas says. But given various safety and technical considerations, a spaceplane making regular trips to orbit at 25 times the speed of sound is the more realistic near-term proposition.

“A lot of people are excited about point-to-point travel at the moment, the thought of going anywhere in the world in four hours just excites people,” he says. “But that is hugely challenging, it’s just orders of magnitude more difficult. I was telling someone from Australia recently that, unfortunately, it’s more difficult to get to Australia than it is to get into space.”
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 11/07/2015 10:08 am
Can't see a Skylon airframer committing until there is a representative demonstration of the SABRE cycle, REL doesn't have an actual product to offer them until then.  Right now the focus will be on that, which is what the tie-up with BAE should hopefully deliver.
Except of course that BAE is an airframer not an engine maker and their biggest contribution to the current development program could actually be the design and development of the test aircraft they wish to fly by 2025,  doing that is very much within their capabilities and not REL's and functionally wouldn't be much different to Taranis so would be a useful activity to give to their aircraft design teams.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 11/07/2015 10:20 am
Can't see a Skylon airframer committing until there is a representative demonstration of the SABRE cycle, REL doesn't have an actual product to offer them until then.  Right now the focus will be on that, which is what the tie-up with BAE should hopefully deliver.
Except of course that BAE is an airframer not an engine maker and their biggest contribution to the current development program could actually be the design and development of the test aircraft they wish to fly by 2025,  doing that is very much within their capabilities and not REL's and functionally wouldn't be much different to Taranis so would be a useful activity to give to their aircraft design teams.

Quite. One thing I am liking about BAE's involvement is the potential for airframe research to be significantly further forward at the end of this test engine development phase than might otherwise have been the case. Let's hope that time is well used.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alpha_Centauri on 11/07/2015 01:11 pm
Can't see a Skylon airframer committing until there is a representative demonstration of the SABRE cycle, REL doesn't have an actual product to offer them until then.  Right now the focus will be on that, which is what the tie-up with BAE should hopefully deliver.
Except of course that BAE is an airframer not an engine maker and their biggest contribution to the current development program could actually be the design and development of the test aircraft they wish to fly by 2025,  doing that is very much within their capabilities and not REL's and functionally wouldn't be much different to Taranis so would be a useful activity to give to their aircraft design teams.

BAE used to be a major airframer but they have steadily eroded that side of their business over the last couple of decades to concentrate on generic platforms that are less dependant on any specific government programme. They are more focussed on things like avionics now.

You are probably right that BAE may well develop test vehicles for SABRE, but I would expect a full Skylon would require them partnering up with an outfit like Airbus.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 11/07/2015 02:42 pm

Can't see a Skylon airframer committing until there is a representative demonstration of the SABRE cycle, REL doesn't have an actual product to offer them until then.  Right now the focus will be on that, which is what the tie-up with BAE should hopefully deliver.
Except of course that BAE is an airframer not an engine maker and their biggest contribution to the current development program could actually be the design and development of the test aircraft they wish to fly by 2025,  doing that is very much within their capabilities and not REL's and functionally wouldn't be much different to Taranis so would be a useful activity to give to their aircraft design teams.

BAE used to be a major airframer but they have steadily eroded that side of their business over the last couple of decades to concentrate on generic platforms that are less dependant on any specific government programme. They are more focussed on things like avionics now.

You are probably right that BAE may well develop test vehicles for SABRE, but I would expect a full Skylon would require them partnering up with an outfit like Airbus.

I increasingly see the parallels with the Taranis technological demonstrator. As that is to drone technology so this will be to hypersonic research.

Wonder if the demonstrator will be manned or a drone?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 11/07/2015 04:56 pm
Can't see a Skylon airframer committing until there is a representative demonstration of the SABRE cycle, REL doesn't have an actual product to offer them until then.  Right now the focus will be on that, which is what the tie-up with BAE should hopefully deliver.
Except of course that BAE is an airframer not an engine maker and their biggest contribution to the current development program could actually be the design and development of the test aircraft they wish to fly by 2025,  doing that is very much within their capabilities and not REL's and functionally wouldn't be much different to Taranis so would be a useful activity to give to their aircraft design teams.

BAE used to be a major airframer but they have steadily eroded that side of their business over the last couple of decades to concentrate on generic platforms that are less dependant on any specific government programme. They are more focussed on things like avionics now.

You are probably right that BAE may well develop test vehicles for SABRE, but I would expect a full Skylon would require them partnering up with an outfit like Airbus.
Absolutely, in fact I was arguing this some pages back when we were discussing prospective consortium members but I think it's still fair to say that BAE is more of an airframer and supplier of things that go into them than they are a maker of engines.
When it comes to Skylon there are definitely things they'll need Airbus as a supplier for but I could see BAE being involved in construction if a UK assembly site is required. BAE has often looked enviously at Lockheed Martin as their main rival and they have extensive involvement in space launch so BAE could be wishing to follow suit.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/07/2015 05:06 pm
I increasingly see the parallels with the Taranis technological demonstrator. As that is to drone technology so this will be to hypersonic research.

Wonder if the demonstrator will be manned or a drone?
I hope not.

Taranis was billed as costing £140m, it's now running about £185m.

The European Neuron project (which seems similar) is listed at about 25m euros, with roughly 75% of the takeoff mass.

That's not exactly the kind of tight cost control you want from a supplier/consortium member.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hanelyp on 11/07/2015 05:09 pm
So, I was watching this interview on CNN and the image below popped up. What is this?

http://www.cnn.com/videos/business/2015/11/04/bae-systems-reaction-engines-mark-thomas-intv-qmb.cnn
That concept looks like someone took an X-30 style scramjet with forebody integrated inlet and aftbody integrated exhaust nozzle, stripped out the scramjet engines the underbody was designed to serve, and stuck sabre engines on wingtips.  I'm thinking with that fuselage shape you might do better with the sabre engines installed center-body where the scramjets would be, using the contoured underbody for inlet and exhaust.

It may look that way, but it's not just an artists' impression or derived from an X-30 style scramjet design. It's the result of an aerothermal study of Skylon:

http://strathprints.strath.ac.uk/41933/1/Brown_et_al_Towards_Robust_Aero_Thermodynamic_Predictions_for_Re_Usable_Single_Stage_to_Orbit_Vehicles.pdf
That looks like a study of reentry aerodynamics at high angle of attack, not the low angle of attack on the way up.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 11/07/2015 05:49 pm
I increasingly see the parallels with the Taranis technological demonstrator. As that is to drone technology so this will be to hypersonic research.

Wonder if the demonstrator will be manned or a drone?
I hope not.

Taranis was billed as costing £140m, it's now running about £185m.

The European Neuron project (which seems similar) is listed at about 25m euros, with roughly 75% of the takeoff mass.

That's not exactly the kind of tight cost control you want from a supplier/consortium member.  :(

I think the 25m euros is the estimated unit cost not the development cost which was 405m euros or £289m also Taranis is autonomous while the Neuron isn't, I don't think.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 11/08/2015 03:46 am
The Space Shuttle was supposed to be orders of magnitude safer than previous vehicles too.  Its projected reliability was far, far greater than what it turned out to be in practice.

Yes, but that was because NASA was trying to happyface its way through an abysmally underfunded development program in which they were forced to heavily compromise their vision to save money, coming straight off the Apollo program which they must have considered the greatest achievement of human history and which had given them the impression that they were invincible.  Lots of doublethink.  The problems with STS were known; they were simply brushed aside.  The same thing happened during operation, in the lead-up to both accidents.  And REL knows this.

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The point is with a new design that is very different from existing systems you usually don't know what will be the real reliability problems.

No, not exactly.  But you can make a fair guess, especially if you've done detailed design studies, which they have.

Besides, Skylon isn't nearly as unique as Shuttle was.  Just about everything about STS was new - the high-pressure closed-cycle hydrogen rockets, the reusable thermal protection system next to (and under) the giant foam-insulated drop tank, the large segmented solids, even the whole idea of a winged reusable orbital vehicle had never been done before.  And the whole thing ended up an insanely hard-to-maintain kludge with built-in issues that could never be fully mitigated.

The main innovations with Skylon are the precooler (proven on the test stand, and apparently surprisingly robust) and the structural concept (which I have a hard time seeing as a potential reliability problem, considering the ease of analysis and the extensive testing regimen).  Standout risks that occur to me are the sweat cooling system for the canards, the potential for FOD on the runway and MMOD on orbit, and the rocket-mode transition (which should get an enormous amount of testing and debugging before the flight test programme so much as starts).

The high-pressure hydrolox rocket engines are a potential issue, but the pressure is much lower than that of the SSME, and pressure makes an enormous difference in the difficulty of designing a reliable engine - look what happened to the service lifetime and estimated failure probabilities on the SSME when they widened the throat slightly.  And as I said, the SABRE avoids a lot of the known issues with the RS-25 - the combustion chamber is oxidizer-cooled, the hydrogen and helium turbopumps are run by warm hydrogen gas turbines, and the oxygen turbopump and air turbocompressor are both run by helium.  There is no turbomachinery downstream of the preburner.

Modern launch vehicles are so unreliable in large part because they're expendable; every flight is the first real test of the vehicle.  F9R doesn't entirely get rid of this issue, nor did STS (even some of the "reusable" parts needed rebuilding).  Skylon does.

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Skylon is more of an airplane than a rocket.
People tend to think that.  It's human nature.  What does it look like that I understand?  OK, so it must behave like that.

But it's not always so.  We can look deeper and see if it really holds.

Yeah, why don't we?  That statement was not intended as a point on its own; it was a lead-in to the rest of the paragraph.

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It is all those things that give it much more risk than a typical airplane.

That might be why the loss-of-vehicle numbers are so much higher than for a typical airplane.  There's an enormous reliability gap between a 737 and a Delta II, and one can make massive improvements over the latter without coming anywhere near the former.

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It takes off and flies like an airplane, which allows it to have full intact abort capability (including engine out) with no black zones.
It only has an abort capability for certain kinds of failures, not all the kinds of failures a more traditional launch vehicle with an abort system has.

No traditional launch vehicle has an abort system.  Manned capsules have abort systems.  The rocket is a writeoff, and if the payload doesn't have an abort system it's a writeoff too.  We were talking about the likely effect of a launcher's reliability on its share of the satellite market, no?

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For example, if Falcon 9 has an engine that is about to explode and destroy the main propellant tank

Skylon's propellant tanks aren't right next to the engines, and if they're serious about aviation-style certification I'd really kinda expect to see measures to prevent engine failures from penetrating the fuselage.  Falcon 9 has something similar, since their engines are right next to one another and they take engine-out capability seriously.

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If the Skylon main prop tanks are about to explode, nothing at all can be done.

Yes, but how likely is that?  Prop tanks don't explode on their own, especially ones that have been flown a minimum of four times already and inspected for issues afterwards.

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And Falcon 9/Dragon has no black zones in its abort capability either.  It's not an "intact" abort in the sense that the first and second stages are possibly lost, but that's a positive, not a negative, because it allows the people to escape and survive when the engines and prop tanks explode.

This isn't about Dragon.  This is about the launch vehicle.  Most payloads don't have escape systems.  And Skylon won't be carrying people until it's been proven to be safe enough to do so; it's primarily a satellite launcher.

Furthermore, if a failure destroys the launch vehicle, (a) you can't inspect it to find out what went wrong, and (b) you need to replace it with a factory-fresh flight unit that may have bugs.  If your failure rate exceeds your retirement rate, this could noticeably damage reliability all by itself.

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It lands like an airplane (well, like a glider), which is a comfortable, well-understood maneuver (particularly for a computer)
The computers doing a Dragon propulsive landing are just as "comfortable" with that landing maneuver.

Falcon 9 isn't, which is part of why it hasn't worked yet.  Compare to Buran.

I admit that isn't an especially strong argument.  However, I still believe that the inclusion of an engine start as a single-string critical-path item with no time for any failure contingency is likely to be bad for reliability, and as I explained above, if the recovery reliability gets bad enough it can indirectly affect the payload delivery reliability.

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If Skylon loses propulsion

Which is massively more unlikely than losing partial propulsion - remember, it has effectively two engines (nowhere near each other) in airbreathing mode, and four in rocket mode.

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Also, propulsive landings give more than one shot at an approach.

Not the way Falcon 9 does them, they don't.

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It is intended to be certified like an airplane, with an extensive test programme putting two prototypes through hundreds of flights including dozens of abort tests,
And Dragon can do exactly the same thing.

Are you claiming that SpaceX plans to fly a specific Dragon 2 flight unit into orbit and back 204 times, and take another one through over a hundred envelope exploration flights including dozens of aborts of various flavours, before so much as offering the capsule on the market?

Besides, I'm not talking about Dragon.  This is a launcher comparison.  Those numbers are even more ridiculous when applied to Falcon 9.

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and each production unit will undergo four test flights before delivery.
Dragon can do exactly the same.

Will it?

But again, this isn't about Dragon.  Falcon 9 won't; of that I'm nearly certain.

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It is also an SSTO, which means that it can wait out bad weather on orbit or divert to almost anywhere in the world (the wings afford a very large cross range),
That has absolutely nothing to do with it being SSTO!

It has everything to do with it.  Falcon 9 can do nothing of the sort, because the recoverable part isn't orbital.

But that's beside the point, because Falcon 9 can simply wait out bad weather on the pad, since the recovery happens so quickly.  This is why I removed this point from my previous post before you made your response.

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and that if staging (a major launch risk) is required at all, it can be done at a leisurely pace after the launch, as more of a payload deployment than a controlled inflight breakup.
Staging of Falcon 9 is in no meaningful way like an "inflight breakup".  That's just a meaningless emotional argument about superficial similarity with no substance to it.

You are deliberately taking my words in the most unreasonable sense possible.  Staging is a significant element in launch risk.  The point I'm making is that Skylon's "staging" procedure is far more benign and can take advantage of procedural risk mitigation strategies that are simply not available to a TSTO of any description.  That's if it's necessary at all, and for a LEO payload it's not.

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And of course it's fully reusable, which means infant mortality should be way down.
SpaceX is closing in on reusability of both their first stage and Dragon.  Both are designed for it.  SpaceX has also said they plan to eventually have a reusable second stage, though they're not pursuing that at the moment.  But you can bet that if the flight rate is high enough to make it make economic sense SpaceX will create a reusable upper stage.  The cost for SpaceX to create a reusable upper stage should be far, far less than the cost to develop Skylon, so the advantage is to SpaceX on the reusability front.

You're really reaching here.  Skylon is completely reusable; it doesn't even drop a "trunk".  There is no way for any system to have an advantage over Skylon "on the reusability front" unless development goes south and they need to do extensive refurbishment like STS (and let me assure you, they have heard of STS; they aren't going into this blind).

By contrast, SpaceX does not currently plan to reuse upper stages (perhaps because it would be fairly costly to get it to work, never mind get it to the level of tested reliability Skylon is targeting), and apparently the question of what to do with the FH core is still open.  Even if they do end up reusing the upper stage, simply stacking a fully reusable TSTO would be enough 'rebuilding' to make it less completely reusable than Skylon, since the stage mating is untested on every flight.

Dragon is, as always, irrelevant to this comparison.

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The REL team has a lot of experience doing research on engine components and writing slideware, not much on systems that actually become operational.

This is not actually true, except in the sense that some of them have been working on Skylon for a while, and Skylon isn't operational yet.  Plenty of REL personnel have had experience on systems that became operational before becoming part of REL, and that includes the founders.

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In other words, those are more like must-not-exceed numbers than optimistic projections.
But there's no way they could possibly know the real reliability.  They are of course optimistic projections not grounded in any evidence.

That doesn't follow.  They don't know the real reliability, but based on the information we have, they do apparently think they can at least guarantee certain numbers regardless.  It is your opinion that isn't grounded in any evidence.

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STS killed more astronauts than any other space launch system in history.

The Challenger accident had nothing to do with the liquid hydrogen systems, and the Columbia accident was a result of a specific design feature that was known to be risky from the start and which Skylon doesn't share.

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STS's problems came from trying to push the edge of what is possible -- exactly what Skylon hopes to do.

No.  STS's problems came from trying to push the edge of what was possible at the time with about half as much money as they needed to actually do it right.  Skylon is not about trying to push the edge of what's possible - it's about using ingenious game-changing ideas to make a reusable SSTO shuttle comfortably possible without having to push the bleeding edge.

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Even those should be greatly mitigated by the extensive flight test programme (so systematic design and maintenance issues can be worked out) and by the highly reusable nature of the whole system (so you don't have untried factory fresh parts on every launch).
Falcon/Dragon has all those advantages too

I will not address Dragon further.  Falcon does not have those advantages, and it won't for a long while if it ever does.  SpaceX didn't kick off their program by putting a pair of reusable vehicles through a series of 400 test flights (the bulk of them orbital), nor have they been holding each individual booster back from launching commercial payloads before its fifth flight, and as far as I know they have shown no sign of doing either of those things in the near future.  And there is currently no plan to do anything other than use a brand new upper stage on every flight.

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but without the disadvantages of having to use liquid hydrogen (very low temperatures and hydrogen working its way into everything, causing leaks and embrittlement)

We know a fair bit more about hydrogen handling in reusable systems than we did in the '60s and '70s (thanks in part to STS), and the engine at least seems to be designed to mitigate hydrogen-related issues.  The issues can be mitigated, and I'd certainly expect them to have a handle on the problem by the end of that monster test programme of theirs.

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and the disadvantages of having to be single-stage to orbit (so there is less margin available for safety).

Apples to oranges.  The whole point of Skylon is that the engine concept enables SSTO without razor-thin margins.

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Based on what we know of the engine, they seem to have circumvented the main issues with the SSME that made it dangerous and maintenance-intensive.
It's premature to make pronouncements about an engine that hasn't been built yet.

Depends on the pronouncement.  We have high-level schematics for SABRE, and we know what the fundamental problems with the SSME were.  We can see that SABRE steers around those problems.

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STS had one catastrophic engine failure -- of a solid engine.

That had nothing to do with hydrogen, unless you're going to argue that the solids were only needed because they went with a hydrogen-fueled TAOS, which is really stretching your point...

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Ummm... Development costs are sunk costs and so have no impact whatsoever on the operational economics.
They affect launch prices (not costs),
No, they affect costs.  Development costs are costs.

They are not costs associated with the ongoing operation of the system.  If you somehow managed to steal a Skylon, you could use it without worrying about the development cost.  Once the development is finished, that outlay becomes part of the price structure (because people want their money back); it's not an ongoing cost.  This is illustrated by the bankruptcy/writeoff/restructuring scenario pippin described.

Frankly I can't believe you challenged me on that.  You've plainly overshot the point of honest disagreement and are in condescending contrarian territory.

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The price a company charges isn't necessarily directly related to the costs.  It often has more to do with the market -- what the market will bear.

True, but if the vehicle was priced higher than its manufacturing cost + profit margin in order to make back the development cost, that raises the minimum price the operator will be willing to charge, because he wants to make back the purchase price.

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Even as matters stand, the numbers they're talking about seem pretty competitive.  The more SpaceX expands the market, the more likely it becomes that Skylon will undercut them.
I don't see any evidence for that.  An expanding market allows SpaceX to lower prices too because its per-flight costs go down when volume goes up too.

Not as much as Skylon's do.  That's the advantage of a fully reusable low-overhead fast-turnaround ground-maneuverable HTOL SSTO, and it's the reason I mentioned the high development costs.

You don't seem to get this - Skylon (if it works out as hoped) looks to be competitive despite the high development cost.  What that high development cost does is increase the slope of the curve so that the system gets more expensive faster as the market shrinks - or in other words, it gets cheaper faster as the market grows.

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there are two factors that argue for it having higher per-flight operational costs: the fact that it uses liquid hydrogen (look at Delta IV's costs versus Atlas V) and the fact that it is single-stage (so it has less mass margin to use making things more rugged and cheaper to maintain).

That doesn't guarantee Skylon's costs will be higher, but it suggests they are likely to be.

No, it doesn't suggest anything of the sort.  You're comparing apples to oranges here; the vehicles are too different to suppose that those factors are likely to be dominant.

Besides, Skylon has plenty of mass margin and a higher structural safety factor than Falcon; the margin troubles show up with the Falcon upper stage.  And hydrogen does have reusability advantages vs. kerosene to go with the disadvantages.

...

There are a lot of unknowns, and I don't want anyone to take this as a confident prediction of the future.  But I do think you are being unfair to Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 11/08/2015 04:20 am
It lands like an airplane (well, like a glider), which is a comfortable, well-understood maneuver (particularly for a computer)

Can you explain the reasoning behind this comment? Chris was discussing "reliability" and abort scenarios. I'm not aware of any mainstream autopilot system that is capable of even an unpiloted emergency landing after a single engine-out, let alone an all-engines-out emergency glide.

I was contrasting it with Falcon 9's hoverslam, which strikes me as a highly tuned accident waiting to happen, with a first-try engine restart on the critical path.  I can imagine the control problem becoming well enough understood for robust performance, but I don't like that engine restart.

No one was discussing abort scenarios until I brought them up.  And who said anything about all engines out?  At least Skylon has a chance in that scenario; Falcon 9 sure as hell doesn't...

Losing one engine is a much more likely scenario (and REL have specifically sized the tail fin to deal with it).  With one engine, you've got options no matter where you are, even if you can't make orbit.

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historically liquid hydrogen systems haven't been as reliable as systems using other sorts of fuel.
Centaur      Expendable
Saturn V     Expendable
DC-X          Suborbital experiment
Ariane 5      Expendable
Delta IV      Expendable
STS           Expendable hydrogen tank, very expensive and high-maintenance engine.
...

Not sure what this list tells you about the reliability of reusable hydrogen rockets.

Not sure why you expected it to tell you anything about the reliability of reusable hydrogen rockets specifically.  Chris was talking about hydrogen vs. other fuels in general.  What the list shows is that there doesn't seem to be a significant effect on the probability of vehicle failure.

All the same, it does tell you something about reusable engines.  One thing it tells you is that the RL-10 is pretty great - the fact that DC-X was a "suborbital experiment" notwithstanding...

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I agree that advocates are grossly underplaying Skylon's complexity and risks

How so?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: TrevorMonty on 11/08/2015 06:16 am
It maybe possible to build and flight test the Skylon without a finished Reaction engine. Existing rocket engines or Reaction engine in rocket mode should provide enough DV to take airframe through the riskier parts of flight envelope.

Even better/cheaper build a subscale version using existing rocket engines. These don't necessary need to be hydrogen fuelled engines either.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 11/08/2015 08:56 am
It maybe possible to build and flight test the Skylon without a finished Reaction engine. Existing rocket engines or Reaction engine in rocket mode should provide enough DV to take airframe through the riskier parts of flight envelope.

Even better/cheaper build a subscale version using existing rocket engines. These don't necessary need to be hydrogen fuelled engines either.

Existing rocket engines would allow the Skylon's ability to take off, change course, navigate and land to be tested. Four things less to worry about when the SABRE is added.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 11/08/2015 11:29 am
It maybe possible to build and flight test the Skylon without a finished Reaction engine. Existing rocket engines or Reaction engine in rocket mode should provide enough DV to take airframe through the riskier parts of flight envelope.

Even better/cheaper build a subscale version using existing rocket engines. These don't necessary need to be hydrogen fuelled engines either.
Not cheaper to the overhaul project through. Whether a subscale model is needed will probably be decided when they have built and tested a full scale sabre engine of the ground. If that engine manages all stages of the flight without any major malfunctions or unexpected issues popping then I suspect they will go for a full scale model, if unexpected issues pop up then they might go for a subscale model. But this will be for testing Sabre engines not simply to test whether skylon model can fly with rocket engines or jet engines attach to it they will use computer simulations for that, which I'm sure they have already done.


An one person above mention costs. Cost per flight is expected to be just 5 million quid, they add 5 million for cost of acquiring Skylon presuming it will still cost 1 billion per unit but I suspect prices there will full as they introduce more 3d printed components,  and they could add another 5 for their profit and still be less than half the price of Falcon 9 whilst potentially being a lot more flexible in the missions it is able to carry out. 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Katana on 11/08/2015 01:59 pm
Orbital reentry of razor-thin tank airframe is something with "razor-thin margins".

Unless somebody reentry and reuse an upperstage before Skylon.

No matter with engines.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: TrevorMonty on 11/08/2015 02:07 pm
Alan Bond said it would cost £350 to get finished engine. £10B to produce Skylon and engines, I think this is large scale manufacturing.

Going from finished engine to flying prototype Skylon would still cost a few £B.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Katana on 11/08/2015 02:28 pm
Subscale models are needed to prove intact vehicle reentry from orbit.

Unless you want to try it with a full scale "reuseable" but really expendable vehicle.

F9R is cheap enough to start from F9 expendable, is Skylon also cheap enough to start from expendable?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 11/08/2015 05:09 pm

Subscale models are needed to prove intact vehicle reentry from orbit.

Unless you want to try it with a full scale "reuseable" but really expendable vehicle.

F9R is cheap enough to start from F9 expendable, is Skylon also cheap enough to start from expendable?

They aren't needed if you're interested in building a hypersonic aircraft & not Skylon.

I think people are still thinking that a subscale model is going to be for Skylon when from what BAE are indicating this isn't their initial aim.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 11/08/2015 05:46 pm
Are you implying BAe has a hypersonic military aircraft in mind, or a passenger aircraft? If military, what's the end product? I'm having a hard time imagine what strike/reconnaissance capability could justify the cost.

And it's been previously argued that a passenger aircraft is likely much harder to pull off (technically and economically) than an SSTO launcher.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: momerathe on 11/08/2015 06:03 pm
Allan Broad said it would cost £350 to get finished engine. £10B to produce Skylon and engines, I think this is large scale manufacturing.

Going from finished engine to flying prototype Skylon would still cost a few £B.

yup, and nobody's going to lay out that kind of investment without knowing the engine's going to work, because with no engine there's no value proposition.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Katana on 11/08/2015 06:09 pm
Reentry of lightweight fuselage = reuseable upperstage, may be more profitable than SSTO itself.

Anyway, if SSTO success but reuse fails, it's still benificial to reuse only engines and leave fuselage in orbit, docking with ISS, and modify into large diameter habitat.
Are you implying BAe has a hypersonic military aircraft in mind, or a passenger aircraft? If military, what's the end product? I'm having a hard time imagine what strike/reconnaissance capability could justify the cost.

And it's been previously argued that a passenger aircraft is likely much harder to pull off (technically and economically) than an SSTO launcher.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 11/08/2015 06:23 pm

Are you implying BAe has a hypersonic military aircraft in mind, or a passenger aircraft? If military, what's the end product? I'm having a hard time imagine what strike/reconnaissance capability could justify the cost.

And it's been previously argued that a passenger aircraft is likely much harder to pull off (technically and economically) than an SSTO launcher.

Well if you read the article posted up thread it sounds like they are very interested in point to point transport.

There seems to be a renewed interest in high speed passenger transport. Hence NASA & its quiet boom technology demonstrator to combat one of the main barriers to supersonic transport that of noise.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 11/08/2015 06:34 pm
Which one? The CNN, FT, and Forbes coverage follow the same pattern: REL talk up SSTO launch, but the press wants to talk about passenger travel, REL agree that's enabled by their technology, but if allowed, state that's not their first priority, and that it's harder than space launch.

Am I missing another article? Or missing a quote in these that suggests point-to-point is the new raison d'être?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 11/08/2015 09:11 pm
Orbital reentry of razor-thin tank airframe is something with "razor-thin margins".

Unless somebody reentry and reuse an upperstage before Skylon.

No matter with engines.

You don't sound like you're familiar with their structure and TPS concept.  It's not a "tank airframe".  The insulated aluminium cryo tanks are suspended inside a truss that provides the fuselage's stiffness and strength (safety factor 1.5 last I heard) made of titanium composite struts (they've already manufactured test struts; before they'd done that the baseline was ordinary CFRP) and titanium nodes, with multilayer foil underneath a flexible corrugated reinforced glass-ceramic skin (from a company in France; last I heard they were working with REL to get the specs up to those of the AEA's defunct System 2).  High-temperature areas use some form of carbon-carbon composite, like on Shuttle or X-37 (note that the X-37 uses much stronger ACC vs. the Shuttle's RCC, and REL knows this).  Heat soak is handled partly by residual hydrogen fuel.  Reentry simulations have indicated a slightly milder thermal environment than REL had been designing for, suggesting that they may not need active cooling at a certain point on the wing leading edge.  They still plan to use sweat cooling to protect the canard-fuselage interface.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 11/09/2015 02:10 am
Allan Broad said it would cost £350 to get finished engine. £10B to produce Skylon and engines, I think this is large scale manufacturing.

The name's Bond. ALAN Bond.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Katana on 11/09/2015 02:47 am
Weight must be kept low, similar to Shuttle ETs, so the thickness of structure and TPS are still limited hard.

No orbital RV of this kind have proved successful before. If it proved sucessful, reuesable upperstage also becomes successful, more competition of conventional TSTO rockets with SSTO.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 11/09/2015 02:56 am
An one person above mention costs. Cost per flight is expected to be just 5 million quid, they add 5 million for cost of acquiring Skylon presuming it will still cost 1 billion per unit but I suspect prices there will full as they introduce more 3d printed components,  and they could add another 5 for their profit and still be less than half the price of Falcon 9 whilst potentially being a lot more flexible in the missions it is able to carry out.

You're comparing RELs projected cost goals after a long, expensive development program to SpaceX costs today.  Surely it makes more sense to compare RELs projected future costs against SpaceX projected future costs.

Shotwell told a satellite industry conference SpaceX is targeting $5-8 million per launch long term.  That's the number to compare Skylon to.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 11/09/2015 03:36 am
An one person above mention costs. Cost per flight is expected to be just 5 million quid, they add 5 million for cost of acquiring Skylon presuming it will still cost 1 billion per unit but I suspect prices there will full as they introduce more 3d printed components,  and they could add another 5 for their profit and still be less than half the price of Falcon 9 whilst potentially being a lot more flexible in the missions it is able to carry out.

You're comparing RELs projected cost goals after a long, expensive development program to SpaceX costs today.  Surely it makes more sense to compare RELs projected future costs against SpaceX projected future costs.

Shotwell told a satellite industry conference SpaceX is targeting $5-8 million per launch long term.  That's the number to compare Skylon to.

$5-8M including an expendable upper stage?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 11/09/2015 04:04 am
An one person above mention costs. Cost per flight is expected to be just 5 million quid, they add 5 million for cost of acquiring Skylon presuming it will still cost 1 billion per unit but I suspect prices there will full as they introduce more 3d printed components,  and they could add another 5 for their profit and still be less than half the price of Falcon 9 whilst potentially being a lot more flexible in the missions it is able to carry out.

You're comparing RELs projected cost goals after a long, expensive development program to SpaceX costs today.  Surely it makes more sense to compare RELs projected future costs against SpaceX projected future costs.

Shotwell told a satellite industry conference SpaceX is targeting $5-8 million per launch long term.  That's the number to compare Skylon to.

$5-8M including an expendable upper stage?

She didn't say, but presumably no, that would be with a reusable upper stage.

SpaceX has said they're not working on a reusable upper stage right now, but they've always said it's their long-term plan.

SpaceX seems to want to grow the market first with somewhat lower costs with first-stage reuse, then later introduce upper stage reuse to lower costs more.  At the flight rate it would take to make Skylon meet its targets, there would be more than enough incentive for SpaceX to make a reusable upper stage.
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 11/09/2015 08:20 am
Which one? The CNN, FT, and Forbes coverage follow the same pattern: REL talk up SSTO launch, but the press wants to talk about passenger travel, REL agree that's enabled by their technology, but if allowed, state that's not their first priority, and that it's harder than space launch.

Am I missing another article? Or missing a quote in these that suggests point-to-point is the new raison d'être?

Yes you are missing an article because it is this one.

http://fortune.com/2015/11/06/bae-commercial-space-launch/


Quote
“This could fundamentally change the way aerospace works,” says Chris Allam, engineering director for BAE’s aerospace business. If the technology works as designed, he says, it could spawn a new breed of aircraft engines capable of much higher speeds and performance.

"A lot of people are excited about point-to-point travel at the moment, the thought of going anywhere in the world in four hours just excites people,” he says. “But that is hugely challenging, it’s just orders of magnitude more difficult. I was telling someone from Australia recently that, unfortunately, it’s more difficult to get to Australia than it is to get into space.”

By the way the fact that the media are more interested in high speed passenger transport than access to space should tell you something alone about where public interest maybe is.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 11/09/2015 01:55 pm

Yes you are missing an article because it is this one.

http://fortune.com/2015/11/06/bae-commercial-space-launch/


Quote
“This could fundamentally change the way aerospace works,” says Chris Allam, engineering director for BAE’s aerospace business. If the technology works as designed, he says, it could spawn a new breed of aircraft engines capable of much higher speeds and performance.

"A lot of people are excited about point-to-point travel at the moment, the thought of going anywhere in the world in four hours just excites people,” he says. “But that is hugely challenging, it’s just orders of magnitude more difficult. I was telling someone from Australia recently that, unfortunately, it’s more difficult to get to Australia than it is to get into space.”

Hardly an authoritative article:
Quote
“The engine would then transition to rocket power to propel the aircraft to space. On its return journey the aircraft could then transition back to jet power and land like a traditional jetliner on a conventional runway."
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/09/2015 02:25 pm
Orbital reentry of razor-thin tank airframe is something with "razor-thin margins".
Welcome to the forum.

The point of the SABRE/Skylon architecture is to make those margins quite wide and hence the design is much more tolerant of small miscalculations in mass and insulation properties.

Let me suggest you read more about SABRE and Skylon before you post again, since you're making assumption s about what is and is not necessary that are simply wrong.

SABRE's benefits to an RLV design, especially an HTOHL like Skylon have been discussed at considerable length within these threads, starting with the expected 2 tonne payload superiority of a Skylon over a (semi) reusable F9.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/09/2015 03:21 pm
It is intended to be certified like an airplane, with an extensive test programme putting two prototypes through hundreds of flights including dozens of abort tests,
And Dragon can do exactly the same thing.

Wow.  ::)

Just wow.

Leaving aside the fact you are conflating launch vehicle with payload AFAIK the most times a capsule has been flown is twice, in the Gemini programme.

So where have SX or Musk said they can do 100s of  cycles, or have stated that they are committed to hundreds of flight per capsule?

There is no experience of flying a capsule more than 2 times to orbit and no idea (outside SX's data files) how close launch and landing stresses push the capsule to structural failure.

That does not make your claim impossible. Merely that there is virtually no experience of doing it and it has never been a design goal, so it's unclear how close to the ultimate tensile limits (rather than the elastic limits) of materials they push current capsule designs.

OTOH A winged vehicle has done 39 flights to and from orbit. Long haul airliners are targeted at 35000 pressurization/depressureization cycles and short hauls 110 000.

So Skylon, at 0.5% of the number of a modern long haul, sounds conservative enough to be quite achievable.

An one person above mention costs. Cost per flight is expected to be just 5 million quid, they add 5 million for cost of acquiring Skylon presuming it will still cost 1 billion per unit but I suspect prices there will full as they introduce more 3d printed components,  and they could add another 5 for their profit and still be less than half the price of Falcon 9 whilst potentially being a lot more flexible in the missions it is able to carry out.

You're comparing RELs projected cost goals after a long, expensive development program to SpaceX costs today.  Surely it makes more sense to compare RELs projected future costs against SpaceX projected future costs.

Shotwell told a satellite industry conference SpaceX is targeting $5-8 million per launch long term.  That's the number to compare Skylon to.

$5-8M including an expendable upper stage?

She didn't say, but presumably no, that would be with a reusable upper stage.
Your memory seems to be failing. Let me refresh it.

Shotwell said this in 2013 in her Keynote speech at Singapore Satellite Forum 2013
Available courtesy of Trent's fine work   here (http://shitelonsays.com/transcript/singapore-satellite-industry-forum-2013-opening-keynote-gwynne-shotwell-2013-06-23)

Her $60m launch price tag clearly references the F9.

2014 Sept 25th. Elon Musk states stage 2 reuse of F9 "uneconomic" and full reusability will only be possible with next generation (BFR) hardware. This is an effect of the environment, not the actual root cause of why it cannot be made economic.  SX remain highly secretive about what that is.

This is where he said it https://www.youtube.com/watch?v=SOpmaLY9XdI
at around 14:20.
Quote
SpaceX has said they're not working on a reusable upper stage right now, but they've always said it's their long-term plan.
IOW for payloads in the 100 tonne+ category, with a suitably larger base price, Never for an F9 sized vehicle. That is simply dead. Musk made that clear when he said roughly "No reusable upper stages will be based on F9 hardware."
Quote
SpaceX seems to want to grow the market first with somewhat lower costs with first-stage reuse, then later introduce upper stage reuse to lower costs more.  At the flight rate it would take to make Skylon meet its targets, there would be more than enough incentive for SpaceX to make a reusable upper stage.
No one knows if the at lowered price will be low enough to grow the market at all, given the cost of the new 2nd stagy you have to stick on at every launch.

But you know this already, so why do keep up this misinformation?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Katana on 11/09/2015 03:37 pm
Payloads are usually 10x more expensive than launch services...simply reducing launch cost won't stimulate market size effectively, unless extremely low cost to enable different market structure.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 11/09/2015 04:11 pm
Which one? The CNN, FT, and Forbes coverage follow the same pattern: REL talk up SSTO launch, but the press wants to talk about passenger travel, REL agree that's enabled by their technology, but if allowed, state that's not their first priority, and that it's harder than space launch.

Am I missing another article? Or missing a quote in these that suggests point-to-point is the new raison d'être?

Yes you are missing an article because it is this one.

http://fortune.com/2015/11/06/bae-commercial-space-launch/


Quote
“This could fundamentally change the way aerospace works,” says Chris Allam, engineering director for BAE’s aerospace business. If the technology works as designed, he says, it could spawn a new breed of aircraft engines capable of much higher speeds and performance.

"A lot of people are excited about point-to-point travel at the moment, the thought of going anywhere in the world in four hours just excites people,” he says. “But that is hugely challenging, it’s just orders of magnitude more difficult. I was telling someone from Australia recently that, unfortunately, it’s more difficult to get to Australia than it is to get into space.”

By the way the fact that the media are more interested in high speed passenger transport than access to space should tell you something alone about where public interest maybe is.

Thanks. Actually I had read that one (and mistakenly referred to it as Forbes rather than Fortune.) I think Allam's quote and your comment speak for themselves, so won't add much more other than to say you are right that the public are perennially interested in shorter journey times (if there's no other cost) but we're also interested in time travel, miracle weight loss, and cures for the common cold.

Given what we know about the tech and business (limited) my guess is that despite high public interest in point-to-point, BAE may not prioritize a project that Allam (their engineering director for aerospace business) considers "orders of magnitude harder than space launch." But I could be wrong.  :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hanelyp on 11/09/2015 04:46 pm
Payloads are usually 10x more expensive than launch services...simply reducing launch cost won't stimulate market size effectively, unless extremely low cost to enable different market structure.
Payloads are expensive driven by demand to get mass down and reliability up, and by no economy of production scale.  If launch costs and delays drop to where launching a replacement isn't such a big deal, there are economies than can be had in the payloads.  Getting the delay to launch a payload down may be a bigger driver here than reducing price.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/10/2015 09:56 am
Payloads are usually 10x more expensive than launch services...simply reducing launch cost won't stimulate market size effectively, unless extremely low cost to enable different market structure.
Payloads are expensive driven by demand to get mass down and reliability up, and by no economy of production scale.  If launch costs and delays drop to where launching a replacement isn't such a big deal, there are economies than can be had in the payloads.  Getting the delay to launch a payload down may be a bigger driver here than reducing price.

There is a small amount of cost data on this subject.

Both the GPS and Iridium programmes needed quite large constellations of satellites. IIRC Iridium hired the man responsible for highly automating mfg of the Macintosh computers. Changed the design to simplify assembly and from memory cut build time by 50%.

I don't know if there's information on the GPS sats in the public domain but logically they should have set up a production team of some kind

NASA did a lot of work on the benefits of design-for-repair on orbit during the 1970's IIRC there are a couple of conference proceedings on the matter, given it was expected the Shuttle was expected to launch 52 times a year and  eventually carry an upper stage.

Current high reliability design uses 3 parallel strings of components with cross straps between all units so you can get one working string from multiple failed parts by bypassing the signals onto another string. This is usually shown as a 2 string process but the 3 string will involve lots  more switches.

Running a single string system means 1/3 the mass (actually a bit less with none of those switches) or 3x the capability at the same mass.

Of course if you can schedule your replacements reliably you might just decide to replace them regardless of failure to ensure uninterrupted coverage.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/11/2015 12:08 am
Not cheaper to the overhaul project through. Whether a subscale model is needed will probably be decided when they have built and tested a full scale sabre engine of the ground. If that engine manages all stages of the flight without any major malfunctions or unexpected issues popping then I suspect they will go for a full scale model, if unexpected issues pop up then they might go for a subscale model. But this will be for testing Sabre engines not simply to test whether skylon model can fly with rocket engines or jet engines attach to it they will use computer simulations for that, which I'm sure they have already done.
Correct. It happens that the SL thrust of a SABRE is about that of Merlin 1d but otherwise you're looking at finding a pair of 138 Klb thrust engines for a full size Skylon or whatever size a sub scale vehicle is.

REL's original test plan was to build 2 "boilerplate" Skylons which they described as "X" and "Y" vehicles. They did not expect the X vehicle to reach orbit but to drive final design for the Y vehicle, which would serve as the final design that would go into production.
Quote
An one person above mention costs. Cost per flight is expected to be just 5 million quid, they add 5 million for cost of acquiring Skylon presuming it will still cost 1 billion per unit but I suspect prices there will full as they introduce more 3d printed components,  and they could add another 5 for their profit and still be less than half the price of Falcon 9 whilst potentially being a lot more flexible in the missions it is able to carry out.
IIRC the figure is  $5m is for propellant and standard launch prep. REL estimated an average of a further $5m averaged over 200 launches for  specific issues on any given flight (nothing on some flights, more on others).

However the price of an F9SR  would only converge on the cost of the Upper Stage plus refurb costs for the 1st stage, unlikely ever to go below about $15m, and probably requiring 8+ launches to get the total package to just over $20m.

Don't expect too much from 3d printing. While I think it can be quite effective for some parts of the engine I think more conventional methods will deliver the necessary production rate and quality.
Remember REL only use cutting edge technology where it is absolutely going to deliver major benefits.

I do think they should be able to do a lot of automated assembly but the joker in the pack is how much all the work they have already done cuts the cost estimates for the later stages, or wheather this R&D was expected to lower mfg and the $12Bn project is the total cost after the cost reductions from the R&D they've been doing have been applied.

The fact remains that Skylon is just very big and when you run aerospace costing models for a vehicle of this size that is the price you get out of them.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 11/12/2015 05:57 pm
Another lecture, 20th January.

http://nearyou.imeche.org/eventdetail/index/11160
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 11/12/2015 11:50 pm
Payloads are usually 10x more expensive than launch services...simply reducing launch cost won't stimulate market size effectively, unless extremely low cost to enable different market structure.


One of the reasons they are so costly is because they are built with lots of redundancies that are needed because the people making it know it so expensive to get stuff into orbit. An it takes a relatively long time to get space on a rocket.

If costs of getting stuff into orbit comes down and it quicker to get stuff back up there,  they can use less redundancies and cheaper hardware and replace hardware as needed. 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 11/13/2015 07:41 am
Mark Thomas being interviewed

http://edition.cnn.com/videos/business/2015/11/04/bae-systems-reaction-engines-mark-thomas-intv-qmb.cnn

Perhaps this is the one people were referring to a couple of pages ago on this thread, but I didn't see a link to it.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 11/18/2015 07:55 am
https://www.flightglobal.com/news/articles/analysis-british-spaceplane-engine-concept-gets-cas-418612/?cmpid=NLC|FGFG|FGFIN-2015-1117-GLOB&sfid=70120000000taAh

Sorry, I am sure this will become a public article soon - you need the free membership to read it now.

The interesting points are:

1) The article suggests that Mark Thomas (REL) and Chris Allam (BAE head of Engineering) think purely UK funding will never be enough.

2) The article says that REL has £10 million from recent fundraising and £20m from BAE so it's "half way to unlocking the UK Space Agency's 60m of matching funding."  They think BAE's investment will galvanise others.

3) The first engine will not  be full size.

The comment about funding seems a bit alarming to me. So really there is a way to go before they get the 60m that we've been taking for granted for so long,
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 11/18/2015 12:30 pm
Just to add as a side point there is no guarantee that article will go free, not all on there do.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 11/18/2015 01:00 pm
https://www.flightglobal.com/news/articles/analysis-british-spaceplane-engine-concept-gets-cas-418612/?cmpid=NLC|FGFG|FGFIN-2015-1117-GLOB&sfid=70120000000taAh

Sorry, I am sure this will become a public article soon - you need the free membership to read it now.

The interesting points are:

1) The article suggests that Mark Thomas (REL) and Chris Allam (BAE head of Engineering) think purely UK funding will never be enough.

2) The article says that REL has £10 million from recent fundraising and £20m from BAE so it's "half way to unlocking the UK Space Agency's 60m of matching funding."  They think BAE's investment will galvanise others.

3) The first engine will not  be full size.

The comment about funding seems a bit alarming to me. So really there is a way to go before they get the 60m that we've been taking for granted for so long,
It a shame that British industry and finance sector don't seem interested in funding this. It also a shame they aren't building a full size engine, which I guess is solely down to lack of funding rather a decision they willingly made.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Ravenger on 11/18/2015 01:30 pm
It also a shame they aren't building a full size engine, which I guess is solely down to lack of funding rather a decision they willingly made.

Originally the plan was to build a sub-scale 'dissected rabbit' engine, with the parts spread out for easy access, then that changed to developing a full-size engine. Looks like the plan has changed again.

To attract further investment Reaction Engines have to prove the Sabre cycle works, as the only part so far fully experimentally proven is the heat-exchanger with frost control mechanism.

So I imagine building a demonstrator engine is the cheapest, quickest and best way to do that. Once they have hardware which proves the entire engine concept is valid then hopefully a lot more investors will jump in and fund the full size flight engine (and with any luck Skylon too)

What I would be interested to know is if the planned demonstrator engine is flight capable (i.e. could be attached to a test aircraft), or if it's the original plan of a 'dissected rabbit' ground test only engine.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 11/18/2015 01:53 pm
What I would be interested to know is if the planned demonstrator engine is flight capable (i.e. could be attached to a test aircraft), or if it's the original plan of a 'dissected rabbit' ground test only engine.

On rereading the quote from Mark Thomas says that demonstration engine now going into design will not be big enough to power Skylon.

Elsewhere, however, they say that they can have SABRE in full scale ground-rig tests before 2020 and a flight vehicle shortly after that.

So what the heck does that mean ? :-).   My reading is that they going to do a small demonstrator first, then a full sized engine  before 2020.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 11/18/2015 02:56 pm

What I would be interested to know is if the planned demonstrator engine is flight capable (i.e. could be attached to a test aircraft), or if it's the original plan of a 'dissected rabbit' ground test only engine.

On rereading the quote from Mark Thomas says that demonstration engine now going into design will not be big enough to power Skylon.

Elsewhere, however, they say that they can have SABRE in full scale ground-rig tests before 2020 and a flight vehicle shortly after that.

So what the heck does that mean ? :-).   My reading is that they going to do a small demonstrator first, then a full sized engine  before 2020.

The engine will probably be used in a subscale technology demonstrator.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 11/18/2015 03:16 pm
what about timelines?
a subscale ground engine is to be readied by end 2017 I guess, if they want to have time to build & test full scale ground engine by 2020.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Ravenger on 11/18/2015 03:46 pm
The engine will probably be used in a subscale technology demonstrator.

I thought that REL had come to the conclusion that a sub-scale engine was actually more technologically difficult than a full-size one, as high speed turbopumps can't easily be scaled down, which is why they were going full scale.

Perhaps they're going full scale (or near full scale) in size, but not full-power. The engine may not be capable of powering Skylon, but as you say could power a smaller demonstrator aircraft.

Though having to develop a sub-scale demonstrator aircraft will of necessity take funding that could otherwise have been applied to a full-scale Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: momerathe on 11/18/2015 03:49 pm
1) The article suggests that Mark Thomas (REL) and Chris Allam (BAE head of Engineering) think purely UK funding will never be enough.
It a shame that British industry and finance sector don't seem interested in funding this. It also a shame they aren't building a full size engine, which I guess is solely down to lack of funding rather a decision they willingly made.

Well, they've always been upfront at saying that the estimated cost for the whole SKYLON development was on the order of £10Bn. There just aren't any UK manufacturers left who can shoulder the whole of that cost, so I don't think this is anything new, just making explicit somehting which was always true.

I am somewhat concerned by she sub-scale engine, though. I just hope it doesn't delay the program overall.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 11/18/2015 04:13 pm
https://www.flightglobal.com/news/articles/analysis-british-spaceplane-engine-concept-gets-cas-418612/?cmpid=NLC|FGFG|FGFIN-2015-1117-GLOB&sfid=70120000000taAh

Sorry, I am sure this will become a public article soon - you need the free membership to read it now.

The interesting points are:

1) The article suggests that Mark Thomas (REL) and Chris Allam (BAE head of Engineering) think purely UK funding will never be enough.

2) The article says that REL has £10 million from recent fundraising and £20m from BAE so it's "half way to unlocking the UK Space Agency's 60m of matching funding."  They think BAE's investment will galvanise others.

3) The first engine will not  be full size.

The comment about funding seems a bit alarming to me. So really there is a way to go before they get the 60m that we've been taking for granted for so long,

£10m sounds pretty tiny for a company with the headcount and assets of REL. While the current reality after BAE coming onboard is undoubtedly positive, I wonder if we'd be hearing bad news soon if they had not. Perhaps this explains why BAE got what appears to be a very good deal.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim Davis on 11/18/2015 04:38 pm
The engine will probably be used in a subscale technology demonstrator.

Is this demonstrator under contract?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 11/18/2015 04:59 pm
https://www.flightglobal.com/news/articles/analysis-british-spaceplane-engine-concept-gets-cas-418612/?cmpid=NLC|FGFG|FGFIN-2015-1117-GLOB&sfid=70120000000taAh
...

2) The article says that REL has £10 million from recent fundraising and £20m from BAE so it's "half way to unlocking the UK Space Agency's 60m of matching funding."  They think BAE's investment will galvanise others.

3) The first engine will not  be full size.

The comment about funding seems a bit alarming to me. So really there is a way to go before they get the 60m that we've been taking for granted for so long,

I believe this is the first time we've heard the UKSA £60m is matching funds, released when REL has their own £60m. The following prior announcements talk about the money being released in the past tense, and to encourage investment in REL. I wonder which it is.

http://www.reactionengines.co.uk/press_release/Press_Release_17July2013_SABRE.pdf
http://www.bbc.com/news/science-environment-23332592
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 11/18/2015 07:01 pm

The engine will probably be used in a subscale technology demonstrator.

I thought that REL had come to the conclusion that a sub-scale engine was actually more technologically difficult than a full-size one, as high speed turbopumps can't easily be scaled down, which is why they were going full scale.

Perhaps they're going full scale (or near full scale) in size, but not full-power. The engine may not be capable of powering Skylon, but as you say could power a smaller demonstrator aircraft.

Though having to develop a sub-scale demonstrator aircraft will of necessity take funding that could otherwise have been applied to a full-scale Skylon.

I imagine a subscale demonstrator would be attractive in publicising the technology beyond its use in Skylon. Other interested parties such as the AFRL would be no doubt invited to view it.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 11/18/2015 08:55 pm
I believe what happened is that they had a large investment that handily exceeded the government funding amount, but the investor pulled out for reasons unknown.

I must say I'm somewhat disappointed in the aerospace business community, but this is a familiar feeling as I am also a fan of Polywell...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 11/19/2015 12:04 am


3) The first engine will not  be full size.


Is that "not large enough to power Skylon, but large enough to power this thing the USAF mentioned they might be interested in?"

If that was it the 60m would hardly be an issue
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 11/19/2015 07:29 am

3) The first engine will not  be full size.


Is that "not large enough to power Skylon, but large enough to power this thing the USAF mentioned they might be interested in?"

Your guess is as good as mine but of course as Pippin said, one would imagine that money was not an issue in that case.

A family member had a small business which got into trouble for what I think were similar reasons - he committed it to expansion and larger overheads and an investor decided not to make what I think was an agreed investment.  Hence I have been waiting with trepidation for this to happen to REL because I don't believe in promises about money - it's not real till it's in your bank account and they can't take it back.


Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: fatjohn1408 on 11/19/2015 12:40 pm
Sorry to take this off topic. I haven't followed this thread in a while and want to get to know a bit more about the precooler. They claim that they can cool air from 1000 °C to -150 °C.

During the test, did they actually do this? How did they heat up the flow to 1000 °C?
If they didn't do that but instead used ambient air. How cold did the air become after it left the precooler?

I would like to know because I might think of an application for just the precooler on its own. But my understanding about it is too limited so far. So any info on the precooler that exceeds the info given on the REL site would be welcome thank you.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: solartear on 11/19/2015 06:15 pm
http://sine.ni.com/cs/app/doc/p/id/cs-16263  or the pdf itself http://sine.ni.com/cs/app/doc/p/id/cs-16263/lang/en/pdf/yes/pdf

Has a nice diagram of the setup. A slightly modified Viper jet engine sucks ambient air through the precooler. They used liquid nitrogen, which is much warmer than liquid hydrogen. The experiment accounted for this.

The problem with cooling air has never been the 1000 C down to 0 C, but the frost from going well below 0 C. The link above shows the test setup was to sustain the airflow and cooling of the air down to -143 C.

I did not find specifics of temperature achieved beyond "substantially below -100 C for more than 5 minutes" and that the test successfully proved the technology.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/20/2015 06:46 am
I believe this is the first time we've heard the UKSA £60m is matching funds, released when REL has their own £60m. The following prior announcements talk about the money being released in the past tense, and to encourage investment in REL. I wonder which it is.

http://www.reactionengines.co.uk/press_release/Press_Release_17July2013_SABRE.pdf
http://www.bbc.com/news/science-environment-23332592
I think so too.

If so it's an even less generous deal that it looked originally.   :(

I imagine a subscale demonstrator would be attractive in publicising the technology beyond its use in Skylon. Other interested parties such as the AFRL would be no doubt invited to view it.
A full size, but not full thrust engine gives you all the drag of a full size engine without all the thrust to overcome it.

This (from REL's PoV) then drags you into a detailed design exercise to fund and build a flight vehicle that's either a scaled Skylon (to preserve the aerodynamics) or a completely 1 off test vehicle.

REL don't like scale models because they have scale effects which have to be compensated for and may not be fully understood, increasing the design risk scaling up.

Likewise the one off test vehicle brings all the problems of designing a flight vehicle without the benefits of transferring the solutions of those problems to Skylon. You'd want to mfg it in as conventional a way as possible to avoid the technical risks of the Titanium framework, ceramic body shell for example.

REL's original concept was for 2 test Skylons, similar in appearance but with evolving capabilities. They did not expect the 1st Skylon to be orbital capable but to give them experience and to discover where they had been conservative on margins (or where they had not been, given one of those "unknown unknowns" that come up in aeronautical testing) for the final orbit capable version.

I'm guessing the did a fair bit of cost modelling on this and this was the plan that had the lowest overall cost to implement.

What is not known outside REL is how all the testing and research has refined their confidence in their models, or equally, if it's shown areas that are not adequately modeled and will need a full scale test vehicle.

REL have made progress, and attracted good staff, by focusing on their goal and not getting side tracked. They may not have moved fast, but they have always moved in the same direction.

I doubt many people in REL have any interest in building a prototype military anything, or the appetite for the endless procurement paperwork that defense contractors seem to love.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 11/20/2015 01:03 pm

I believe this is the first time we've heard the UKSA £60m is matching funds, released when REL has their own £60m. The following prior announcements talk about the money being released in the past tense, and to encourage investment in REL. I wonder which it is.

http://www.reactionengines.co.uk/press_release/Press_Release_17July2013_SABRE.pdf
http://www.bbc.com/news/science-environment-23332592
I think so too.

If so it's an even less generous deal that it looked originally.   :(

I imagine a subscale demonstrator would be attractive in publicising the technology beyond its use in Skylon. Other interested parties such as the AFRL would be no doubt invited to view it.
A full size, but not full thrust engine gives you all the drag of a full size engine without all the thrust to overcome it.

This (from REL's PoV) then drags you into a detailed design exercise to fund and build a flight vehicle that's either a scaled Skylon (to preserve the aerodynamics) or a completely 1 off test vehicle.

REL don't like scale models because they have scale effects which have to be compensated for and may not be fully understood, increasing the design risk scaling up.

Likewise the one off test vehicle brings all the problems of designing a flight vehicle without the benefits of transferring the solutions of those problems to Skylon. You'd want to mfg it in as conventional a way as possible to avoid the technical risks of the Titanium framework, ceramic body shell for example.

REL's original concept was for 2 test Skylons, similar in appearance but with evolving capabilities. They did not expect the 1st Skylon to be orbital capable but to give them experience and to discover where they had been conservative on margins (or where they had not been, given one of those "unknown unknowns" that come up in aeronautical testing) for the final orbit capable version.

I'm guessing the did a fair bit of cost modelling on this and this was the plan that had the lowest overall cost to implement.

What is not known outside REL is how all the testing and research has refined their confidence in their models, or equally, if it's shown areas that are not adequately modeled and will need a full scale test vehicle.

REL have made progress, and attracted good staff, by focusing on their goal and not getting side tracked. They may not have moved fast, but they have always moved in the same direction.

I doubt many people in REL have any interest in building a prototype military anything, or the appetite for the endless procurement paperwork that defense contractors seem to love.  :(

If the military are going to give you development money for what is after all an untried technology in actual usage then you would be foolish in the extreme to turn your nose at it, if it helps reach your goals. Anyway now that BAE have a seat at the table I suspect your belief in what REL will or will not do may be misplaced.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Ravenger on 11/20/2015 02:09 pm
If the military are going to give you development money for what is after all an untried technology in actual usage then you would be foolish in the extreme to turn your nose at it, if it helps reach your goals. Anyway now that BAE have a seat at the table I suspect your belief in what REL will or will not do may be misplaced.

Remember that Alan Bond had a terrible experiences with the government cancelling cancelling HOTOL, then slapping an official secrets order on the patents for the RB545 HOTOL engine which he had designed. He spent decades working around his own patents to produce SABRE.

There's also the ITAR issue, where too heavy involvement in the USA could could prevent REL from exporting their technology, though they have been working with the US military to confirm the engine's feasibility.

REL have had bad dealings with government departments before, and so may be very careful before they sign any deals that could relinquish any control over the SABRE project. How that squares with BAE buying a stake in REL remains to be seen.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: simonbp on 11/20/2015 02:24 pm
There's also the ITAR issue, where too heavy involvement in the USA could could prevent REL from exporting their technology, though they have been working with the US military to confirm the engine's feasibility.

ITAR has recently (a few months ago) become significantly less restrictive about space hardware. That may in fact have allowed the BAE deal to happen (speculation).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 11/20/2015 03:34 pm

If the military are going to give you development money for what is after all an untried technology in actual usage then you would be foolish in the extreme to turn your nose at it, if it helps reach your goals. Anyway now that BAE have a seat at the table I suspect your belief in what REL will or will not do may be misplaced.

Remember that Alan Bond had a terrible experiences with the government cancelling cancelling HOTOL, then slapping an official secrets order on the patents for the RB545 HOTOL engine which he had designed. He spent decades working around his own patents to produce SABRE.

There's also the ITAR issue, where too heavy involvement in the USA could could prevent REL from exporting their technology, though they have been working with the US military to confirm the engine's feasibility.

REL have had bad dealings with government departments before, and so may be very careful before they sign any deals that could relinquish any control over the SABRE project. How that squares with BAE buying a stake in REL remains to be seen.

I imagine it was less restrictive ITAR environment that partly interested BAE in the first place, plus they have plenty of experience with dealing with military bureaucracy.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/20/2015 08:35 pm
If the military are going to give you development money for what is after all an untried technology in actual usage then you would be foolish in the extreme to turn your nose at it,
There is no indication that has happened.
Quote
if it helps reach your goals. Anyway now that BAE have a seat at the table I suspect your belief in what REL will or will not do may be misplaced.
Well there's what they will do and there's what they would like to do if they did not have other constraints.

It's not about funding. It's about control.

Remember that Alan Bond had a terrible experiences with the government cancelling cancelling HOTOL, then slapping an official secrets order on the patents for the RB545 HOTOL engine which he had designed. He spent decades working around his own patents to produce SABRE.

There's also the ITAR issue, where too heavy involvement in the USA could could prevent REL from exporting their technology, though they have been working with the US military to confirm the engine's feasibility.

REL have had bad dealings with government departments before, and so may be very careful before they sign any deals that could relinquish any control over the SABRE project. How that squares with BAE buying a stake in REL remains to be seen.
Various staff at REL also dealt with Concorde, where repeated government interference delayed the programme and wasted a lot of funds, basically becuse the French thought you could build an SST with 70 seats.

There's also the ITAR issue, where too heavy involvement in the USA could could prevent REL from exporting their technology, though they have been working with the US military to confirm the engine's feasibility.

ITAR has recently (a few months ago) become significantly less restrictive about space hardware. That may in fact have allowed the BAE deal to happen (speculation).
AFAIK this solely applies to communications satellites and parts. Launch vehicles remain dual use with all the problems that implies.

http://bizwest.com/relaxed-munitions-rules-pave-way-for-aerospace-exports/

Gives a background on the changes.

I imagine it was less restrictive ITAR environment that partly interested BAE in the first place, plus they have plenty of experience with dealing with military bureaucracy.
http://bizwest.com/relaxed-munitions-rules-pave-way-for-aerospace-exports/

Suggests your imagination is wrong.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 11/20/2015 09:23 pm
Just a thought on squaring the full scale test rig with the demonstration engine not big enough to power Skylon.
SABRE 3 was always two engines with a single precooler and compressor, four combustion chambers and nozzles and two of everything else, I'm not sure whether SABRE 4 is similarly designed on the airbreathing side but if it is you could imagine a demonstration engine with full scale parts but built with only one of everything so it is effectively half thrust. That way you can test pretty much everything but with a smaller engine.

I think the really pessimistic view on the BAE stake purchase is that there is no plan behind it at all, only that REL were failing to raise sufficient financing to keep everything going and the Government, having put substantial backing behind it both financial and reputationally, asked BAE to step in. £20m is really not that large compared to the size of BAE's UK government business and it's not that hard to see it as a small favour to keep a customer happy. If that's the case then BAE may have little to no thoughts on Skylon, SABRE or REL at all.
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 11/20/2015 09:55 pm
If the military are going to give you development money for what is after all an untried technology in actual usage then you would be foolish in the extreme to turn your nose at it,
There is no indication that has happened.
Quote
if it helps reach your goals. Anyway now that BAE have a seat at the table I suspect your belief in what REL will or will not do may be misplaced.
Well there's what they will do and there's what they would like to do if they did not have other constraints.

It's not about funding. It's about control.

Remember that Alan Bond had a terrible experiences with the government cancelling cancelling HOTOL, then slapping an official secrets order on the patents for the RB545 HOTOL engine which he had designed. He spent decades working around his own patents to produce SABRE.

There's also the ITAR issue, where too heavy involvement in the USA could could prevent REL from exporting their technology, though they have been working with the US military to confirm the engine's feasibility.

REL have had bad dealings with government departments before, and so may be very careful before they sign any deals that could relinquish any control over the SABRE project. How that squares with BAE buying a stake in REL remains to be seen.
Various staff at REL also dealt with Concorde, where repeated government interference delayed the programme and wasted a lot of funds, basically becuse the French thought you could build an SST with 70 seats.

There's also the ITAR issue, where too heavy involvement in the USA could could prevent REL from exporting their technology, though they have been working with the US military to confirm the engine's feasibility.

ITAR has recently (a few months ago) become significantly less restrictive about space hardware. That may in fact have allowed the BAE deal to happen (speculation).
AFAIK this solely applies to communications satellites and parts. Launch vehicles remain dual use with all the problems that implies.

http://bizwest.com/relaxed-munitions-rules-pave-way-for-aerospace-exports/

Gives a background on the changes.

I imagine it was less restrictive ITAR environment that partly interested BAE in the first place, plus they have plenty of experience with dealing with military bureaucracy.
http://bizwest.com/relaxed-munitions-rules-pave-way-for-aerospace-exports/

Suggests your imagination is wrong.

I didn't actually say military funding has happened. Rather I was implying that a subscale demonstrator would increase the likelihood of such funding.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 11/22/2015 10:29 pm
Regarding ITAR. I was wondering, a while back there was a lecture where, I think, Bond was saying that there may end up being two Skylon models, an American one and a European one because of the whole ITAR problem.

Previously when thinking about possible potential Skylon consortiums it had seemed likely to be Airbus based (assuming it ever happens) and unlikely to contain any American players but that would put all the risk of failure on Airbus and leave the Americans out in the cold should the project succeed.
So I was wondering whether a consortium involving both Boeing and Airbus was possible where there is two production lines and ITAR sensitive components are duel developed and sourced resulting in distinct  American and EU models but where the costs and risks of Skylon development, as well as the potential profits are spread across the entire industry.

Is that setup at all possible under the ITAR rules?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Khadgars on 11/22/2015 10:50 pm
I'll admit I haven't gone through the 5 threads on this subject, and though I wish my brothers across the pond the best I don't see how this architecture pans out successfully.

It feels like the shuttle, which flew but didn't fly 52 times per year or reduce cost.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 11/23/2015 06:33 am

I'll admit I haven't gone through the 5 threads on this subject, and though I wish my brothers across the pond the best I don't see how this architecture pans out successfully.

It feels like the shuttle, which flew but didn't fly 52 times per year or reduce cost.

It's not like the Shuttle much at all, other than they both have wings. Really it's closer to aviation than any winged space vehicle so far to have flown.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hanelyp on 11/23/2015 01:22 pm
It's not like the Shuttle much at all, other than they both have wings. Really it's closer to aviation than any winged space vehicle so far to have flown.
That's certainly the objective.  That's also a lot closer to what was promised for the shuttle than what was delivered.  Hopefully they can get a vehicle not crippled by overwhelming maintenance demands.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 11/23/2015 02:14 pm
It's not like the Shuttle much at all, other than they both have wings. Really it's closer to aviation than any winged space vehicle so far to have flown.
That's certainly the objective.  That's also a lot closer to what was promised for the shuttle than what was delivered.  Hopefully they can get a vehicle not crippled by overwhelming maintenance demands.

Even if it is, the more important thing is that they focus on eleminating those maintenance demands through upgrades and redesigns.

One of the biggest issue with the shuttle was that very little attempt was made to decrease the amount of maintenance needed after each flight and that was down to the lack of money available to Nasa.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 11/23/2015 10:29 pm
REL are aware of what happened with STS and appear to be attempting to minimize maintenance requirements.  Plus there's no indication of an arbitrary cost cap like the one that forced STS into the form we know.

- the TPS is much more friendly, consisting of large flexible panels, and manual inspection and maintenance is projected to take two days, though automation may be able to improve on that.

- the SABRE is lower pressure than the SSME, and by its unusual layout eliminates a number of corrosion and seals issues associated with the latter.  The mass penalty for this is largely absorbed by the requirements of the airbreathing cycle, since it needs a helium loop anyway.

- the number of fluids on board seems to be fairly well limited, with LH2, LOX, helium, water, nitrogen for the payload bay and tires, possibly a coolant for the payload bay door radiators, and...  maybe hydraulic fluid, if they don't go electromechanical?  (You can indeed do EM brakes, but honestly brake fluid is probably a fairly solid bet.)  There are certainly no toxic consumables; the OMS actually uses the same engines as the upper stage, and power is provided by hydrogen fuel cells and/or hydrolox APUs.

(Shuttle apparently (http://llis.nasa.gov/llis_lib/pdf/1033536main_SPST_Current%20STS_Shortfalls_10-18-05.pdf) employed 52 unique fluids (not 54; missile-grade air and nitric oxide are listed as "deleted"), and had 102 fluid subsystems involving 25 unique fluids that had to be serviced every flight, and in a number of cases systems using a particular fluid did not share storage and umbilicals, the standout examples being helium with 17 separate fluid subsystems and gaseous nitrogen with 20 separate service interfaces.  There were three moderately and three severely toxic fluids involved.)

- the vehicle is a single piece, fully reusable.  No dropping pieces that have to be retrieved or remanufactured and reintegrated for flight.  The only thing it drops en route to orbit is the brake coolant water.  It is also ground maneuverable and can self-ferry, which greatly eases logistics - no barges or crawlers or giant cranes.  The payload interface is standardized, as shown in the User's Manual available on REL's website, in contrast to STS which required the interfaces to be designed for each payload.

...

It seems to me that even if the initial version shows unacceptable maintenance properties, it has much more potential for low overhead than STS did.  And since the initial testing and certification involves about three times the number of flights made during the entire STS program, this sort of thing should show up early and could be largely solved before the vehicle even enters service.

A large part of why STS was so maintenance intensive is the fact that subsystems were designed and optimized independently with little thought given to maintainability.  It isn't inherent to the spaceplane concept.

One of the biggest issue with the shuttle was that very little attempt was made to decrease the amount of maintenance needed after each flight and that was down to the lack of money available to Nasa.

That's not strictly true.  For instance, SSME maintenance was reduced by 57% over the life of the program, and Block III would have dropped it further.  But yeah, major changes would have required a massive design overhaul - basically Shuttle II, which there was no money for.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 11/23/2015 11:48 pm
When, if ever, will Skylon fly? Anyone want to put down a prediction?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 11/24/2015 06:55 am
NET 2028?

(2019 full size ground engine. 2020-21 funding iatus. 2022 consortium created. 2023 subscale demonstrato 2025 beginning construction of full scale models. 2027 they are ready to fly, 2028 beginning of orbital testing)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/24/2015 01:38 pm
When, if ever, will Skylon fly? Anyone want to put down a prediction?
1st flight.

8 years after full funding starts with the current plan.

5 years if they can manage to launch a zero payload demonstrator that flies the whole mission with their existing funding and the rest of the world "discovers" that it works as described.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 11/24/2015 10:55 pm
A quick tangent on military applications for REL/Skylon. One capability that could command a fat check from deep defense coffers is anywhere/anytime rapid reconnaissance. I was thinking that Skylon could be good for this, but I've just read that the Falcon F9R-FT first stage is supposedly capable of SSTO, i.e. when carrying no second stage or payload+fairing. If it could manage to heft cameras etc., then that could give you overflight imagery of anywhere in less than ~30 minutes. Skylon would have one advantage over the Falcon, however: it wouldn't look exactly like a pre-emptive ICBM launch.  :o

Disclaimer: I've no idea if the SSTO claims for F9 S1 are true, or if it's capable of doing a once-around, or re-entering from orbital speed. The point is simply that while a Skylon could be useful for reconnaissance, there could be other, cheaper options available to military planners.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 11/25/2015 12:36 am
When, if ever, will Skylon fly? Anyone want to put down a prediction?
1st flight.

8 years after full funding starts with the current plan.

5 years if they can manage to launch a zero payload demonstrator that flies the whole mission with their existing funding and the rest of the world "discovers" that it works as described.
I meant an actual year.

It's likely that even if it flies, it will never get "full funding" until it's basically flying.

Anyone have a year?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Elmar Moelzer on 11/25/2015 12:53 am
One capability that could command a fat check from deep defense coffers is anywhere/anytime rapid reconnaissance.
Isn't it sad that military is getting so much more funding that space flight that we have to go look there for "fat checks"?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 11/25/2015 12:58 am
Anyone have a year?

Why?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 11/25/2015 01:44 am
Anyone have a year?

Why?
Just wondering. I find it useful when people passionate about a thing (myself included) actually put down their opinion numerically, mark their beliefs to market, as it were.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/25/2015 06:35 am
Anyone have a year?

Why?
Just wondering. I find it useful when people passionate about a thing (myself included) actually put down their opinion numerically, mark their beliefs to market, as it were.
What a good idea.

What were your dates for when SX would recover it's first F9 booster? BFR flight? MCT flight?
I'm curious

I'll note that Musk said of the crew escape system on Dragon 2.0 "3 years once we get full funding."
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/25/2015 06:36 am
A quick tangent on military applications for REL/Skylon. One capability that could command a fat check from deep defense coffers is anywhere/anytime rapid reconnaissance.
Only if a government issues a request for it. Defense contractors don't buy stuff unless a government has already paid them (much more) for it.
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I was thinking that Skylon could be good for this, but I've just read that the Falcon F9R-FT first stage is supposedly capable of SSTO, i.e. when carrying no second stage or payload+fairing. If it could manage to heft cameras etc., then that could give you overflight imagery of anywhere in less than ~30 minutes. Skylon would have one advantage over the Falcon, however: it wouldn't look exactly like a pre-emptive ICBM launch.  :o
"Anywhere" provided it's at a 28 deg slant to the equator or within the plane change range of an F9. Incidently you're confusing SSTO with reusability.

What (I think) you're thinking about is an SSTO and landing for reuse. That still gives you all the orbital velocity and therefore all the problems SX say make 2nd stage reuse "uneconomic"
so won't happen.
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Disclaimer: I've no idea if the SSTO claims for F9 S1 are true, or if it's capable of doing a once-around, or re-entering from orbital speed. The point is simply that while a Skylon could be useful for reconnaissance, there could be other, cheaper options available to military planners.
Given the excellent mass fraction of the booster, and the fact it's got a GNC package on board to do barge landings if you didn't install the landing legs and grid fins (and the ETL can carry a single stage rigidly) then yes an expendable SSTO with some payload seems pretty credible.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 11/25/2015 07:49 am
Incidently you're confusing SSTO with reusability.

Nope.

I was thinking of the sort of mission USAF wanted from Shuttle, so sufficient cross range to get home in a single orbit is needed, and no small feat.

And to be fair you should mention that Falcon Stage 2 reusability is harder because it typically returns from geostationary transfer orbit.

But my point was not to argue that Elon can sell a Spy Falcon to USAF, but that it's darned difficult to find applications for Skylon that are uniquely compelling other than satellite launch. Others here think there military applications could help get the thing built, and i was exploring that.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 11/25/2015 08:36 am
And to be fair you should mention that Falcon Stage 2 reusability is harder because it typically returns from geostationary transfer orbit.

That's not the only reason.  It's what makes it so hard that Elon said he wouldn't even try.

Regardless, I don't see why safe reentry is necessary, any more than a modern spy satellite has to drop film canisters.

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it's darned difficult to find applications for Skylon that are uniquely compelling other than satellite launch.

Most of what was uniquely useful about STS is also possible with Skylon, which is almost certain to be vastly cheaper.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 11/25/2015 12:13 pm
Anyone have a year?

Why?
Just wondering. I find it useful when people passionate about a thing (myself included) actually put down their opinion numerically, mark their beliefs to market, as it were.

I've thought for a while that REL has an 80% chance they get a working engine built by 2020 but only a 40% chance they can get a consortium put together to build Skylon.
Should that consortium be built I see an IOC of Skylon in a possible range between 2028 -2032 with 2030 most likely. An IOC of 2028 means that the ISS could still be used as part of the testing programmes and is only 3 years late based off their last published programme schedule and is in the middle of Mark Thomas's 10-15 years. However the BAE deal and the numbers that came with it make me more pessimistic on schedule.
Generally when the Skylon launch market is being discussed I'm thinking 2030 so I'll pick that, with the provisos that I think there's only a 40% chance of the consortium at all. 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/25/2015 01:58 pm

Nope.

I was thinking of the sort of mission USAF wanted from Shuttle, so sufficient cross range to get home in a single orbit is needed, and no small feat.
Basically that was the theft of a Russian satellite.

An item that would have either happened during WWIII or started WWIII.

The technical description for this was insane.

As it happens I think REL have indicated Skylon and the SABRE 4 cycle would give this capability (or very close to it) as it just has much better aerodynamics than Shuttle.
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And to be fair you should mention that Falcon Stage 2 reusability is harder because it typically returns from geostationary transfer orbit.

But my point was not to argue that Elon can sell a Spy Falcon to USAF, but that it's darned difficult to find applications for Skylon that are uniquely compelling other than satellite launch. Others here think there military applications could help get the thing built, and i was exploring that.
Which could be said of all launch vehicles.

"Military applications" of Skylon are basically putting military payloads into orbit.

If you want reusability and fast turnaround IE "responsive space" as the military tend to call it, then Skylon can deliver it to military customers, as it can to all customers.

"Weaponizing" a Skylon is plot for a straight-to-download thriller.

If  you've got those skills and that funding you can cause a lot more mayhem a lot more cheaply.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hanelyp on 11/25/2015 03:31 pm
A quick tangent on military applications for REL/Skylon. One capability that could command a fat check from deep defense coffers is anywhere/anytime rapid reconnaissance. ...
Presuming a minimal altitude good for only a modest number of orbits, how much payload is Skylon expected to be capable of lifting to a high inclination orbit?  If enough for a good telescope in the payload bay it might offer overflights of a target of urgent interest on shorter notice than the SR-71 did.  A peripheral question to such an operation is how willing and able would the target of such an overflight be to shoot at the spacecraft?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 11/25/2015 03:39 pm
"Weaponizing" a Skylon is plot for a straight-to-download thriller.
If  you've got those skills and that funding you can cause a lot more mayhem a lot more cheaply.  :(

I agree.

Most of what was uniquely useful about STS is also possible with Skylon, which is almost certain to be vastly cheaper.

Also agree. But we're back at the classic chicken-and-egg problem for Skylon: if money and politics were no obstacle then I'm confident we'd be reaping the benefits of Skylon launchers in the near term future - including STS-style capabilities and low launch prices. But realistically, how can the political and financial case be made?

In a different universe where there were no other credible projects that could potentially reduce launch costs through re-use, Skylon would surely attract attention from investors. And similarly, if SLS were not looking like it could actually fly then large-scale space projects could be enabled via multiple cheap Skylon launches, autonomous docking, and fuel depots, etc. And if the Ariane-6 procurement had been a bit later... Etc., etc.

Please don't misunderstand my gloomy comments, I want to believe there's a way to get Skylon financed and built, but need some help staying optimistic. Anyone?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 11/25/2015 08:42 pm


In a different universe where there were no other credible projects that could potentially reduce launch costs through re-use, Skylon would surely attract attention from investors.

If there were no other credible projects that could potentially reduce launch costs through re-use why would anyone need to invest in it?  If SpaceX or Blue Origin lowers launch costs through reuse is Boeing going to just exit the launch market or are they going to invest in reuse? Is Airbus just going to exit the launch market or are they going to invest in reuse?
The only launch provider that can launch Falcon is SpaceX, the only launch provider that can launch New Shephard is Blue Origin for everybody else there's what? Well if they care to invest there's Skylon, which every launch provider can buy.
There's 14 active launch service providers globally, only one of which is SpaceX. In a potential age of reusable launch they all have to be launching something competitive or go out of business.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 11/25/2015 09:43 pm
Presuming a minimal altitude good for only a modest number of orbits, how much payload is Skylon expected to be capable of lifting to a high inclination orbit?

User's Manual v2.1 says a little over 8 tonnes to 160 km sun-synch, given a launch site at 30°.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 11/25/2015 11:25 pm
Anyone have a year?

Why?
Just wondering. I find it useful when people passionate about a thing (myself included) actually put down their opinion numerically, mark their beliefs to market, as it were.
What a good idea.

What were your dates for when SX would recover it's first F9 booster? BFR flight? MCT flight?
I'm curious

I'll note that Musk said of the crew escape system on Dragon 2.0 "3 years once we get full funding."
Irrelevant and off-topic, but yes, I did mark down my predictions to market. Not sure about BFR/MCT, but there was a thread for voting on F9 booster recovery that I voted in.

No need to be defensive nor to change the topic to SpaceX.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 11/26/2015 12:44 am


In a different universe where there were no other credible projects that could potentially reduce launch costs through re-use, Skylon would surely attract attention from investors.

If there were no other credible projects that could potentially reduce launch costs through re-use why would anyone need to invest in it?  If SpaceX or Blue Origin lowers launch costs through reuse is Boeing going to just exit the launch market or are they going to invest in reuse? Is Airbus just going to exit the launch market or are they going to invest in reuse?
The only launch provider that can launch Falcon is SpaceX, the only launch provider that can launch New Shephard is Blue Origin for everybody else there's what? Well if they care to invest there's Skylon, which every launch provider can buy.
There's 14 active launch service providers globally, only one of which is SpaceX. In a potential age of reusable launch they all have to be launching something competitive or go out of business.

I think you've succeeded in laying out a hopeful and plausible scenario for Skylon. It just involves waiting a number years. IIUC the story goes something like:

1] By ~2020, REL have a working development engine, AND SpaceX are undercutting the competition by reaping the rewards of their reusable first stage.

2] Faced with either paying high prices for expendable launchers, or ceding the launch market to SpaceX (and Blue?) interested parties band together and form a consortium which cumulatively has the financial clout and risk capacity to complete a next generation vehicle that can compete with SpaceX.

Now that semi-reuse has been demonstrated there is a desire to skip a generation ahead of the competition, and Skylon fits the bill as a fully reusable SSTO. Hopefully Franscesco's timeline of orbital testing in 2028 could still be kept.

Such a scenario is dependent as much on geopolitical/financial realities as the rocket equation, but who knows - perhaps such as consortium could be assembled. There are precedents: Concorde, the Channel Tunnel, and of course the ISS come to mind. Even Ariane.

Viewing the problem this way does prompt some interesting new questions: For example, the Russians and Chinese have not put much energy into re-use thus far. Their indigenous expendable programs are surely expensive, and there must be some pressure internally to find more cost-effective ways to launch commercial/civilian payloads.

Such a consortium would need to be truly multinational - so no one put RAF roundels on the wings  ;).

And we'd likely see parts of development farmed out to member countries Ariane-style.

Or perhaps if we stretch the timeline out to where ESA is looking beyond Ariane 6, it could just be Ariane 7.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 11/26/2015 12:50 am
I would love that kind of scenario. It's been too long before we've seen some real fight by foreign launch providers on the technology front.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RonM on 11/26/2015 01:07 am
Such a consortium would need to be truly multinational - so no one put RAF roundels on the wings  ;).

Oh, I was so looking forward to a Queen's Own Skylon Squadron.  :)

I would love that kind of scenario. It's been too long before we've seen some real fight by foreign launch providers on the technology front.

Yes, Europe needs to get into the fight on the technology front.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Oli on 11/26/2015 02:04 am
Now that semi-reuse has been demonstrated

Semi-reuse has been demonstrated 35 years ago.

New Shepard is designed for suborbital tourism, that's a market that could potentially support a very high flight rate. No such market will exist for orbital spaceflight anytime soon (i.e. decades), and whether Skylon could create that market is very uncertain at best.

Why does REL not design an engine for suborbital tourism? I don't understand REL's obsession with SSTO, it sometimes makes me question whether their technology is ready for reality.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: tl6973 on 11/26/2015 08:35 am
Why does REL not design an engine for suborbital tourism? I don't understand REL's obsession with SSTO, it sometimes makes me question whether their technology is ready for reality.

Because there is no need for a complex new engine class for suborbital flight

you can easily achieve this using legacy rocket technology

you can get a fair way to achieving it with jet engines alone: a MiG-25M got to 123,500ft, in 1977

In fact, do you even need an engine at all? http://worldviewexperience.com/voyage/#flight-profile

Sub-orbital flight is about going up (100km),  moderately fast (M3), for a bit

Orbital flight is about going insanely fast (M25), moderately up (150km +)

The fast is much much harder than the up, which is why SABRE is important for Orbital flight but unnecessary for suborbital flight
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Archibald on 11/26/2015 10:23 am
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Concorde, the Channel Tunnel

Excuse me, but those are not very good examples. We all know that Concorde was a money pit, but the Shunnel economic case was a major boondoggle. The Eurotunnel company lost tons and tons of money, to the great pleasure of the poor guys who had bought shares in it. Never, ever buy any share in Eurotunnel.
I don't know what the situation is today, but in the 90's the shunnel was losing money pretty horribly.

As for the ISS, in 1984 it was to cost $8 billion, but it ended at $100 billion, twelve times more !
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 11/26/2015 11:54 am
Now that semi-reuse has been demonstrated

Semi-reuse has been demonstrated 35 years ago.

New Shepard is designed for suborbital tourism, that's a market that could potentially support a very high flight rate. No such market will exist for orbital spaceflight anytime soon (i.e. decades), and whether Skylon could create that market is very uncertain at best.

Why does REL not design an engine for suborbital tourism? I don't understand REL's obsession with SSTO, it sometimes makes me question whether their technology is ready for reality.

On which data do you assume there such a high market for suborbital flights and there is not for orbital ones?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 11/26/2015 12:03 pm
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Concorde, the Channel Tunnel

Excuse me, but those are not very good examples. We all know that Concorde was a money pit, but the Shunnel economic case was a major boondoggle. The Eurotunnel company lost tons and tons of money, to the great pleasure of the poor guys who had bought shares in it. Never, ever buy any share in Eurotunnel.
I don't know what the situation is today, but in the 90's the shunnel was losing money pretty horribly.

As for the ISS, in 1984 it was to cost $8 billion, but it ended at $100 billion, twelve times more !

In fact, since 2011 Eurotunnel is a fantastic money machine for an infrastructural project, with net profits touching 100M /Y. It is probably the highest revenue from infrastructural projects ever.
This said, YES: if you were a early investor, you had a considerable part of the initial capital written off.
But this is the whole point: IF someone develops Skylon, their product will become an exceptional money machine. The question is IF developing it is profitable, not if operating it is that.

Besides, I'd like to stress, once more, that infrastructure projects have strong positive externalities on the economy besides the profitability of selling tickets. You don't evaluate the construction of a motorway or of a railway simply assessing whether you will sell enough tickets: you first and foremost estimate the impact of the infrastructure on the economy.
And I can assure you that the impact of a infrastructure potentially bringing LEO costs as down as 600 $/KG is enormous, regardless of the fact it is profitable or not selling tickets.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Oli on 11/26/2015 04:02 pm
Why does REL not design an engine for suborbital tourism? I don't understand REL's obsession with SSTO, it sometimes makes me question whether their technology is ready for reality.

Because there is no need for a complex new engine class for suborbital flight

you can easily achieve this using legacy rocket technology

How's that even an argument?

New Shepard does staging, because an engine failure would be fatal otherwise. Its engine is also high-thrust, despite using hydrogen.

SpaceShipTwo uses a carrier aircraft.

The XCOR Lynx is the only runway takeoff/landing single stage vehicle, but it doesn't exactly win a trophy when it comes to payload delivered (passengers, cabin size).

So I think in principle an air-breathing rocket engine would very attractive for suborbital flight. Whether REL's technology would be useful/cost-effective is another question of course, but have they actually considered it?

On which data do you assume there such a high market for suborbital flights and there is not for orbital ones?

700 individuals have signed up for a ride on SS2. The Futron space tourism study sees a potential demand of 1'298 passengers per year at a $100k price, and 15'712 passengers at $50k. That's a lot flights.

The same study sees demand for orbital tourism as well, but we're absolutely nowhere near the price point where it would have a significant impact on todays flight rates. In fact the study expects 60 passengers per year at $5m, but that's at least an order of magnitude less expensive than commercial crew, and even then it would only lead to maybe 10 more flights.

Other than that I don't see any potential market. Even a constellation like OneWeb can easily be deployed with "a few" expendable launchers.

P.S. Of course the Futron study could be total bull****, but I haven't come across anything better.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 11/26/2015 04:06 pm


In a different universe where there were no other credible projects that could potentially reduce launch costs through re-use, Skylon would surely attract attention from investors.

If there were no other credible projects that could potentially reduce launch costs through re-use why would anyone need to invest in it?  If SpaceX or Blue Origin lowers launch costs through reuse is Boeing going to just exit the launch market or are they going to invest in reuse? Is Airbus just going to exit the launch market or are they going to invest in reuse?
The only launch provider that can launch Falcon is SpaceX, the only launch provider that can launch New Shephard is Blue Origin for everybody else there's what? Well if they care to invest there's Skylon, which every launch provider can buy.
There's 14 active launch service providers globally, only one of which is SpaceX. In a potential age of reusable launch they all have to be launching something competitive or go out of business.

I think you've succeeded in laying out a hopeful and plausible scenario for Skylon. It just involves waiting a number years. IIUC the story goes something like:

1] By ~2020, REL have a working development engine, AND SpaceX are undercutting the competition by reaping the rewards of their reusable first stage.

2] Faced with either paying high prices for expendable launchers, or ceding the launch market to SpaceX (and Blue?) interested parties band together and form a consortium which cumulatively has the financial clout and risk capacity to complete a next generation vehicle that can compete with SpaceX.

Now that semi-reuse has been demonstrated there is a desire to skip a generation ahead of the competition, and Skylon fits the bill as a fully reusable SSTO. Hopefully Franscesco's timeline of orbital testing in 2028 could still be kept.

Such a scenario is dependent as much on geopolitical/financial realities as the rocket equation, but who knows - perhaps such as consortium could be assembled. There are precedents: Concorde, the Channel Tunnel, and of course the ISS come to mind. Even Ariane.

Viewing the problem this way does prompt some interesting new questions: For example, the Russians and Chinese have not put much energy into re-use thus far. Their indigenous expendable programs are surely expensive, and there must be some pressure internally to find more cost-effective ways to launch commercial/civilian payloads.

Such a consortium would need to be truly multinational - so no one put RAF roundels on the wings  ;).

And we'd likely see parts of development farmed out to member countries Ariane-style.

Or perhaps if we stretch the timeline out to where ESA is looking beyond Ariane 6, it could just be Ariane 7.

As I think BAE has shown none of the interested parties have to wait until REL have a ground demonstration engine as for the low low price of whatever they can find down the back of the respective counches they can by a stake in the company and do due diligence with own engineers on whether a fully functional engine is an inevitability at this point and as for just sitting back and waiting to see whether a competitor does come in and radically disrupt your business, generally speaking by that point it's usually too late.
 The time to be making strategic investments to see off a competitor is before they start taking your business, the relevant launch providers should be studying what SpaceX is doing today, making their best estimate of their capabilities in ten years, 20 years time and the launch markets that will exist then and then investing in capabilities accordingly.

Should a consortium be formed next year then by the published roadmap 2024 is possible, but the negotiations to form such an enterprise are long and complex and it would be very easy to say we don't have to invest anything because (insert reusable System) isn't going to change anything because (delete as applicable)  it wont work/our customers can't buy it/our customers are guaranteed by the state.

As for China, interestingly, there were a couple of Chinese papers at this years IAC that kind of talked about SABRE or were SABRE influenced, so I think they're clearly thinking about an indigenous response to SABRE technology.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 11/26/2015 04:13 pm
Why does REL not design an engine for suborbital tourism? I don't understand REL's obsession with SSTO, it sometimes makes me question whether their technology is ready for reality.

Because there is no need for a complex new engine class for suborbital flight

you can easily achieve this using legacy rocket technology

How's that even an argument?

New Shepard does staging, because an engine failure would be fatal otherwise. Its engine is also high-thrust, despite using hydrogen.

SpaceShipTwo uses a carrier aircraft.

The XCOR Lynx is the only runway takeoff/landing single stage vehicle, but it doesn't exactly win a trophy when it comes to payload delivered (passengers, cabin size).

So I think in principle an air-breathing rocket engine would very attractive for suborbital flight. Whether REL's technology would be useful/cost-effective is another question of course, but have they actually considered it?

On which data do you assume there such a high market for suborbital flights and there is not for orbital ones?

700 individuals have signed up for a ride on SS2. The Futron space tourism study sees a potential demand of 1'298 passengers per year at a $100k price, and 15'712 passengers at $50k. That's a lot flights.

The same study sees demand for orbital tourism as well, but we're absolutely nowhere near the price point where it would have a significant impact on todays flight rates. In fact the study expects 60 passengers per year at $5m, but that's at least an order of magnitude less expensive than commercial crew, and even then it would only lead to maybe 10 more flights.

Other than that I don't see any potential market. Even a constellation like OneWeb can easily be deployed with "a few" expendable launchers.

P.S. Of course the Futron study could be total bull****, but I haven't come across anything better.

Commercial crew isn't, exactly, Skylon, is it?
Skylon operational cost is projected to be 5M, and the module is projected to transport 20 pp. This returns a ticket to orbit for 250.000, which is about the same price than VG. So one should expect a particular reason for people to fly suborbital and not orbital, when prices are close, in order to justify the claim that there is a different in market size....
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 11/26/2015 04:18 pm
ANYWAY, if any REL employee is listening.

the UK has formalized a 8 billions investment in the European Fund for Strategic Investment, which finances long-term, strategic investment in technologically intensive products which have high expected returns but are too risky for the privates to invest in the short term.
8 BN Eur is a big sum, which gives to the UK gvt some leverage. The instrument is perfect for REL because it works as a backing for private investors, removing or greatly reducing risks associated with financing the project.
The more I investigate the instrument, the more I believe this is exactly what REL needs.

I strongly advise you to get in touch with the EFSI. REL, those are your guys.

General information on EFSI can be found here. http://ec.europa.eu/priorities/jobs-growth-investment/plan/efsi/index_en.htm. financing applications are mediated through the European Investment Bank investment committee: the link for applications is provided in the main link above. If Skylon is not a strategic investment lacking private backing due to financial risks, then who is?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 11/26/2015 07:14 pm
Skylon's biggest market potential is point-to-point transport. I know that's not how it's designed, but it dwarfs the orbital launch market (which they're probably going to lose to the likes of SpaceX and Blue Origin anyway).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 11/26/2015 07:31 pm
Skylon's biggest market potential is point-to-point transport. I know that's not how it's designed, but it dwarfs the orbital launch market (which they're probably going to lose to the likes of SpaceX and Blue Origin anyway).

I 'like'd the P2P bit!
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 11/26/2015 09:43 pm
Skylon's biggest market potential is point-to-point transport. I know that's not how it's designed, but it dwarfs the orbital launch market (which they're probably going to lose to the likes of SpaceX and Blue Origin anyway).

Don't see either ever being able to match Skylon 5 million pounds per launch price.
Spacex even if all components could be recovered at some point in the future would still require days, if not weeks worth of work for it to be ready for it next flight.

Blue origin have yet to achieve orbit.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/27/2015 08:00 am
Skylon's biggest market potential is point-to-point transport. I know that's not how it's designed, but it dwarfs the orbital launch market (which they're probably going to lose to the likes of SpaceX and Blue Origin anyway).
VTVL systems take substantial hits for being SSTO. Multi stage VTVL reusable takes substantial hits for reintegration and Musk has said reuse of a 2nd stage in F9 sized payloads is dead, although he won't say why.

So you can have (maybe) reuse when the BFR appears in 100 tonne lots and a baseline price which with 15-20 years of launch price inflation will probably make a current Atlas V launch look cheap. In fact this is exactly the rationale for SLS.  :(

These things are quite easy to model and very hard to defeat. To increase the market you need to lower both the $/lb cost and retain the absolute payload size, otherwise you're selling 1/2 a payload at 1/2 price at best.  At worst you have a vehicle with a sticker price of X$/lb but you send up 90% empty, provided of course someone buys that launch, otherwise it's an expense SX will have to fund from their paying customers.

The obvious fixes (better Isp and better structural weight) are very difficult to achieve and very difficult to achieve with robust safety margins.

No a Skylon can't land on Mars. But it can build a Mars mission in 15 tonne blocks, at $5-10m a block.

So I'd like to think Musk would be pragmatic enough to buy a couple and run his project that way.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Archibald on 11/27/2015 10:01 am
P2P is very hard, because ballistics are hard. The issue is that trajectories are very "pointy" - you have to fly very high and fast for little horizontal distance.
For a transatlantic flight of 6500 km you need a speed of (roughly) 5 km/s. Orbital speed of 7 km/s give you a range of 10 000 km at best.Meanwhile the trajectory is so pointy you hand up flying through the lowest Van Allen radiation belts( 500 miles high or even more)

 Unfortunately, current ultra-long range Boeing and Airbus are flying 18 000 km or more. Travelling 18 000 km using P2P would take as much energy as Earth escape, or beyond.

Ballistics are a harsh mistress.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 11/27/2015 10:15 am
VTVL systems take substantial hits for being SSTO. Multi stage VTVL reusable takes substantial hits for reintegration and Musk has said reuse of a 2nd stage in F9 sized payloads is dead, although he won't say why.

Any all-rocket system takes a huge hit for being SSTO; winged HTO is probably counterproductive on something with engines that light.  And Musk did in fact say why F9 won't be fully reusable; it's because it's too hard to get the upper stage back from a GTO mission.  He also applied it specifically to the kerosene systems, citing Isp issues.  Do you have a reference where he says that any F9-sized upper stage reuse is off the table?

Travelling 18 000 km using P2P would take as much energy as Earth escape, or beyond.

No, you can travel as far as you want without ever having to exceed orbital velocity.  Think about it...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 11/27/2015 12:04 pm
Skylon's biggest market potential is point-to-point transport. I know that's not how it's designed, but it dwarfs the orbital launch market (which they're probably going to lose to the likes of SpaceX and Blue Origin anyway).

I'm don't really think both those things can be true.
Skylon's launch price is predicted to be heavily flight rate dependant, the incremental launch cost is very low and at high flight rates the launch price can fall quite low.

If as you posit point to point transport is a huge potential market for Skylon and that that market dwarfs the launch market in which SpaceX and Blue Origin participate then by definition the Skylon launch rate must dwarf the SpaceX and Blue Origin launch rate and thus the the profitable Skylon launch price must fall far below that achievable by SpaceX and Blue Origin. Thus it can't really be true that Skylon could own P2P but lose orbital launch, that doesn't make sense.

Taking your prediction to its logical conclusion in the longer term the Skylon technology can be applied to hypersonic passenger aircraft which is an even larger market than point to point requiring much more demanding engineering, by which point the shared technology base and flight experience will lead to 2nd and 3rd generation Skylons with massively improved lifetimes and maintenance costs as Skylon is just one aircraft type in a vastly larger technology ecosystem of similar aircraft all driving forward technology development and spreading the cost of it and numbering vastly more than there are  reusable VTOL rocket orbital launchers.
 So in the long run it really can't make sense.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/27/2015 02:00 pm
Any all-rocket system takes a huge hit for being SSTO; winged HTO is probably counterproductive on something with engines that light.  And Musk did in fact say why F9 won't be fully reusable; it's because it's too hard to get the upper stage back from a GTO mission.
That's a little more detailed but fails to explain what the detailed problem is.
Quote
He also applied it specifically to the kerosene systems, citing Isp issues.  Do you have a reference where he says that any F9-sized upper stage reuse is off the table?
Quote
I'll need to review the MIT presentation he gave. IIRC he said "F9 and F9 derived." Obviously an interesting question would would  an F9 sized Methalox system be viable?

So in the long run it really can't make sense.
What can't make sense, or do you mean his statements form a logical paradox where something has to be true and false at the same time?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 11/27/2015 04:19 pm


So in the long run it really can't make sense.
What can't make sense, or do you mean his statements form a logical paradox where something has to be true and false at the same time?

I meant that it that it couldn't both be true the Skylon could be successful in providing point to point transport and at same time fail to provide the lowest priced orbital launch and that the logical conclusion of success at point to point transport is in the long term development of dedicated hypersonic air transport using the same Skylon derived technology which for the reasons stated means that it really can't be true that Sklyon derived systems could prove superior at revolutionising air travel but fail to be better at orbital launch than staged reusable rockets, i.e. the statement doesn't make any sense.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 11/27/2015 09:23 pm
It could be true if Falcon ends up cheaper at a moderately high flight rate than Skylon does at a very high flight rate.  That doesn't seem especially likely to me, but we don't actually know yet...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 11/27/2015 10:47 pm
It could be true if Falcon ends up cheaper at a moderately high flight rate than Skylon does at a very high flight rate.  That doesn't seem especially likely to me, but we don't actually know yet...

Well, we won't know for more than a decade. I take there is a consensus, on this forum, that we will be lucky to see Skylon offering commercial trips by 2030.... which has a huge implication: for that moment, we will have finally known whether a sustainable market has emerged or not, and to what extent launching costs affect demand for launches. both aspects conjure to higher demand: R&D developing applications, and lower launching costs in making them profitable.

BTW, if you guys could contribute to the little study I am doing on historic launching costs (you can find the link here: http://forum.nasaspaceflight.com/index.php?topic=38888.0) it would help estimating some degree of elasticity. It would also be good to have a chat about the total size of the launch markets over the years, so to have better computations...

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ANTIcarrot on 11/28/2015 09:50 pm
Skylon's biggest market potential is point-to-point transport. I know that's not how it's designed, but it dwarfs the orbital launch market (which they're probably going to lose to the likes of SpaceX and Blue Origin anyway).
Do not forget the potential market for point to point delivery of 200lb warheads. While it might be nice to imagine investors looking towards space, I'm sure investors BAE is looking at Skylon and thinking 'mach 5 cruise missile' or '150,000ft bomber'. If the engine works, and can be made to work on something a little more practical, like methane (which it supposedly can) then that is something they can sell to a lot of customers, whether the space business works out or not.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/29/2015 10:15 am
Do not forget the potential market for point to point delivery of 200lb warheads. While it might be nice to imagine investors looking towards space, I'm sure investors BAE is looking at Skylon and thinking 'mach 5 cruise missile' or '150,000ft bomber'. If the engine works, and can be made to work on something a little more practical, like methane (which it supposedly can) then that is something they can sell to a lot of customers, whether the space business works out or not.
This is not SABRE, it's the Scimitar M5 cruise engine for the LAPCAT A2 version.

Armed forced are very wary of any cryogenics outside of LV's. Everything else runs on room temperature liquids or solids.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 11/29/2015 11:38 am
I'm definetively not an expert, but with a 15 T payload, Couldn't skylon carry a weapon optimized for re-entry up to orbit, and release the warhead just above target?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: alexterrell on 11/29/2015 12:50 pm
Couldn't skylon carry a weapon optimized for re-entry up to orbit, and release the warhead just above target?
In just the same way as any other launch vehicle could?

Yes. Russia, the USA, and a few other countries already have several thousand of these.

The ICBM killed off the strategic nuclear bomber 50 years ago. Skylon won't bring it back.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 11/29/2015 05:45 pm
I'm definetively not an expert, but with a 15 T payload, Couldn't skylon carry a weapon optimized for re-entry up to orbit, and release the warhead just above target?
True, but as others have pointed out it's a very expensive way to carry out this task and if you have the skills (and funding) to do it anyway you already have the means to carry much more cost effective forms of warfare.

I meant that it that it couldn't both be true the Skylon could be successful in providing point to point transport and at same time fail to provide the lowest priced orbital launch and that the logical conclusion of success at point to point transport is in the long term development of dedicated hypersonic air transport using the same Skylon derived technology which for the reasons stated means that it really can't be true that Sklyon derived systems could prove superior at revolutionising air travel but fail to be better at orbital launch than staged reusable rockets, i.e. the statement doesn't make any sense.

Yes I'd agree with that.  REL's focus has been orbital launch. It seems to believe they would succeed at something that was not their core focus, but fail at their core goal.

It could be true if Falcon ends up cheaper at a moderately high flight rate than Skylon does at a very high flight rate.  That doesn't seem especially likely to me, but we don't actually know yet...
Good point. But let's keep in mind the Skylon consortium will sell Skylons. It's up to the operators what the launch rate is
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Ravenger on 11/30/2015 11:13 am
I'm not sure if this has been posted, but I've not seen this video before:

Richard Varvil's lecture at DEVLOP3D conference in May 2015.

https://www.youtube.com/embed/41vVZWTw4hQ
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 11/30/2015 05:55 pm
This serves to remind us that as late as Q1 this year REL were still after $360M for their Phase 3.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 11/30/2015 09:04 pm
I'm definetively not an expert, but with a 15 T payload, Couldn't skylon carry a weapon optimized for re-entry up to orbit, and release the warhead just above target?
True, but as others have pointed out it's a very expensive way to carry out this task and if you have the skills (and funding) to do it anyway you already have the means to carry much more cost effective forms of warfare.

I meant that it that it couldn't both be true the Skylon could be successful in providing point to point transport and at same time fail to provide the lowest priced orbital launch and that the logical conclusion of success at point to point transport is in the long term development of dedicated hypersonic air transport using the same Skylon derived technology which for the reasons stated means that it really can't be true that Sklyon derived systems could prove superior at revolutionising air travel but fail to be better at orbital launch than staged reusable rockets, i.e. the statement doesn't make any sense.

Yes I'd agree with that.  REL's focus has been orbital launch. It seems to believe they would succeed at something that was not their core focus, but fail at their core goal.

It could be true if Falcon ends up cheaper at a moderately high flight rate than Skylon does at a very high flight rate.  That doesn't seem especially likely to me, but we don't actually know yet...
Good point. But let's keep in mind the Skylon consortium will sell Skylons. It's up to the operators what the launch rate is

An if the Skylon operator is truly ruthless they will massively undercut SpaceX prices , drive them into bankruptcy and then raise their prices to cover the cost of launches and buying new Skylons.
It the ruthless, no prisoner approach to the space business.  Whether this is entirely possible depends on whether the US military would use such an skylon operator even if they are based in the US and under US management. We have seen the US military go the expensive option even where are cheaper ones available just so they could keep their friends in employment.

An wouldn't put it pass congress from banning Skylon from US airspace to protect US rocket manufacturers or banning Skylon operators from being able to bid on US military satellite contract either.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Khadgars on 11/30/2015 09:21 pm
I'm definetively not an expert, but with a 15 T payload, Couldn't skylon carry a weapon optimized for re-entry up to orbit, and release the warhead just above target?
True, but as others have pointed out it's a very expensive way to carry out this task and if you have the skills (and funding) to do it anyway you already have the means to carry much more cost effective forms of warfare.

I meant that it that it couldn't both be true the Skylon could be successful in providing point to point transport and at same time fail to provide the lowest priced orbital launch and that the logical conclusion of success at point to point transport is in the long term development of dedicated hypersonic air transport using the same Skylon derived technology which for the reasons stated means that it really can't be true that Sklyon derived systems could prove superior at revolutionising air travel but fail to be better at orbital launch than staged reusable rockets, i.e. the statement doesn't make any sense.

Yes I'd agree with that.  REL's focus has been orbital launch. It seems to believe they would succeed at something that was not their core focus, but fail at their core goal.

It could be true if Falcon ends up cheaper at a moderately high flight rate than Skylon does at a very high flight rate.  That doesn't seem especially likely to me, but we don't actually know yet...
Good point. But let's keep in mind the Skylon consortium will sell Skylons. It's up to the operators what the launch rate is

An if the Skylon operator is truly ruthless they will massively undercut SpaceX prices , drive them into bankruptcy and then raise their prices to cover the cost of launches and buying new Skylons.
It the ruthless, no prisoner approach to the space business.  Whether this is entirely possible depends on whether the US military would use such an skylon operator even if they are based in the US and under US management. We have seen the US military go the expensive option even where are cheaper ones available just so they could keep their friends in employment.

An wouldn't put it pass congress from banning Skylon from US airspace to protect US rocket manufacturers or banning Skylon operators from being able to bid on US military satellite contract either.

Talking about decimating SpaceX? Skylon is over a decade away from being operational, if it even flies at all.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/01/2015 12:04 am
Talking about decimating SpaceX? Skylon is over a decade away from being operational, if it even flies at all.
You need to keep in mind a couple of things about this scenario.

The F9 Semi Reusable is not an Apples to Apples comparison with Skylon in terms of payload, flexibility or recurring costs.

The BFR which is meant to be the fully reusable SX LV  is also realistically at least a decade away as well. It took SX 4 years to get to go from zero to a gas generator engine, which have powered 20-40 ELVs and ICBM's over the years.

However there are no full flow ORSC engine in the West to study. There is no SP8000 volume dedicated to them. SX will will be starting a lot  further back on the development path. Making it VTVL (even with the improved Isp of ORSC) will still make it a very structurally demanding task.

No one has ever done a full VTO upper stage return from orbit, while Shuttle demonstrated a roughly airplane shaped vehicle that returned from orbit 134 times. Currently SX still has not demonstrated a booster stage landing.

I'll also point out the the aircraft design flow has been executed thousands of times over last century, rather than the few 10s of ELV's or ICBM's or the 2 cycles of STS and Buran.

Skylon looks very different to what people thing of when they think of "space launch vehicle" but in many ways it's the conservative lower risk option if SABRE delivers its performance targets.

It just won't make a very good nuclear weapons delivery system.

I don't think most people would find that too big a flaw.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RonM on 12/01/2015 04:01 am
Couldn't skylon carry a weapon optimized for re-entry up to orbit, and release the warhead just above target?
In just the same way as any other launch vehicle could?

Yes. Russia, the USA, and a few other countries already have several thousand of these.

The ICBM killed off the strategic nuclear bomber 50 years ago. Skylon won't bring it back.

While I agree Skylon would not be used as a bomber, we have to get our facts straight. ICBMs did not kill off the strategic nuclear bomber 50 years ago. Russia and the US still have strategic bombers today that carry nuclear weapons.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 12/01/2015 04:21 am
New article on Skylon.

Interestingly, Mark Thomas emphasizes that the SABRE engine is highly scalable, and continues the trend of inviting the press to talk about vehicle concepts in addition to Skylon...

Quote
“This is a really versatile propulsion system that we’re developing. It is an air-breathing rocket engine that can go from zero to five times the speed of sound and for the space-access variant, 25 times the speed of sound, and has a huge range of operation. The other advantage of this engine is that it’s highly scaleable.”
The ability to up or down-size the concept is undoubtedly a trump card.

http://www.telegraph.co.uk/finance/newsbysector/industry/engineering/12023867/British-technology-company-to-transform-air-and-space-travel-with-pioneering-new-engine-design.html
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 12/01/2015 12:41 pm
New article on Skylon.

Interestingly, Mark Thomas emphasizes that the SABRE engine is highly scalable, and continues the trend of inviting the press to talk about vehicle concepts in addition to Skylon...

Quote
“This is a really versatile propulsion system that we’re developing. It is an air-breathing rocket engine that can go from zero to five times the speed of sound and for the space-access variant, 25 times the speed of sound, and has a huge range of operation. The other advantage of this engine is that it’s highly scaleable.”
The ability to up or down-size the concept is undoubtedly a trump card.

http://www.telegraph.co.uk/finance/newsbysector/industry/engineering/12023867/British-technology-company-to-transform-air-and-space-travel-with-pioneering-new-engine-design.html

"“We don’t see anybody working on anything like Sabre. To do something with a single propulsion system is the dream ticket. "

...."except the Chinese. The Chinese don't have to worry about 'the market' for it and are already showing interest. So if we don't bloody get on with it they will kick our butts, like they are going to with everything else.", he should have added.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 12/01/2015 01:09 pm
I'm definetively not an expert, but with a 15 T payload, Couldn't skylon carry a weapon optimized for re-entry up to orbit, and release the warhead just above target?
True, but as others have pointed out it's a very expensive way to carry out this task and if you have the skills (and funding) to do it anyway you already have the means to carry much more cost effective forms of warfare.

I meant that it that it couldn't both be true the Skylon could be successful in providing point to point transport and at same time fail to provide the lowest priced orbital launch and that the logical conclusion of success at point to point transport is in the long term development of dedicated hypersonic air transport using the same Skylon derived technology which for the reasons stated means that it really can't be true that Sklyon derived systems could prove superior at revolutionising air travel but fail to be better at orbital launch than staged reusable rockets, i.e. the statement doesn't make any sense.

Yes I'd agree with that.  REL's focus has been orbital launch. It seems to believe they would succeed at something that was not their core focus, but fail at their core goal.

It could be true if Falcon ends up cheaper at a moderately high flight rate than Skylon does at a very high flight rate.  That doesn't seem especially likely to me, but we don't actually know yet...
Good point. But let's keep in mind the Skylon consortium will sell Skylons. It's up to the operators what the launch rate is

An if the Skylon operator is truly ruthless they will massively undercut SpaceX prices , drive them into bankruptcy and then raise their prices to cover the cost of launches and buying new Skylons.
It the ruthless, no prisoner approach to the space business.  Whether this is entirely possible depends on whether the US military would use such an skylon operator even if they are based in the US and under US management. We have seen the US military go the expensive option even where are cheaper ones available just so they could keep their friends in employment.

An wouldn't put it pass congress from banning Skylon from US airspace to protect US rocket manufacturers or banning Skylon operators from being able to bid on US military satellite contract either.

I don't see neither thing happening, for various reasons.
1. there won't be a skylon operator. there will be skylon operatorS, which means that- once the price is down- it will stay down as an effect of competition.
2. if SpaceX is only a service provider for LEO, in the very long run either they will develop something competitive, or they will by a skylon themselves.
3. if SpaceX will think itself as producer and vendor of exploration vassels, they will buy a Skylon and use it to assemble any deep space vehicle they'd like to sell/use.

In sum, I see no reason why SpaceX should disappear, and why US should ban Skylons. as the most space-advanced nation in the globe, as well as the nation with highest security concerns on space in the globe, they will be those profiting more of cheap access. Rather than banning Skylons from US, they will attempt to prevent unfriendly countries from acquiring them!
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 12/01/2015 01:39 pm
I'm definetively not an expert, but with a 15 T payload, Couldn't skylon carry a weapon optimized for re-entry up to orbit, and release the warhead just above target?
True, but as others have pointed out it's a very expensive way to carry out this task and if you have the skills (and funding) to do it anyway you already have the means to carry much more cost effective forms of warfare.

I meant that it that it couldn't both be true the Skylon could be successful in providing point to point transport and at same time fail to provide the lowest priced orbital launch and that the logical conclusion of success at point to point transport is in the long term development of dedicated hypersonic air transport using the same Skylon derived technology which for the reasons stated means that it really can't be true that Sklyon derived systems could prove superior at revolutionising air travel but fail to be better at orbital launch than staged reusable rockets, i.e. the statement doesn't make any sense.

Yes I'd agree with that.  REL's focus has been orbital launch. It seems to believe they would succeed at something that was not their core focus, but fail at their core goal.

It could be true if Falcon ends up cheaper at a moderately high flight rate than Skylon does at a very high flight rate.  That doesn't seem especially likely to me, but we don't actually know yet...
Good point. But let's keep in mind the Skylon consortium will sell Skylons. It's up to the operators what the launch rate is

An if the Skylon operator is truly ruthless they will massively undercut SpaceX prices , drive them into bankruptcy and then raise their prices to cover the cost of launches and buying new Skylons.
It the ruthless, no prisoner approach to the space business.  Whether this is entirely possible depends on whether the US military would use such an skylon operator even if they are based in the US and under US management. We have seen the US military go the expensive option even where are cheaper ones available just so they could keep their friends in employment.

An wouldn't put it pass congress from banning Skylon from US airspace to protect US rocket manufacturers or banning Skylon operators from being able to bid on US military satellite contract either.

Talking about decimating SpaceX? Skylon is over a decade away from being operational, if it even flies at all.
Any investor in SpaceX should be looking at the decade long outlook because that how long it will take for them to get any money back.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/01/2015 02:52 pm
While I agree Skylon would not be used as a bomber, we have to get our facts straight. ICBMs did not kill off the strategic nuclear bomber 50 years ago. Russia and the US still have strategic bombers today that carry nuclear weapons.
Then the question would then be how many current B52 and B2 missions are flying nuclear weapons?

My guess is few or none, just as the USN stopped carriers carrying nuclear bombs
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/01/2015 02:59 pm
Rather than banning Skylons from US, they will attempt to prevent unfriendly countries from acquiring them!
In reality this would be done by REL planned sales policy anyway.

The trouble is US control means the end of any sort of potential free market, given their obsession with technology control (which drove India to develop it's own LH2 upper stage and other failures of the policy).

REL indicate Skylon can operate from anywhere in the world. To get the kind of market were space launch becomes a commodity there have to be multiple customers.

Assuming Skylon works and Musk is a pragmatist I would expect him to buy a pair, short cut all the R&D and move straight to building his Mars transport, built around the ability to deliver to orbit on demand.

The downside is Skylon threatens the F9 revenue stream in several ways.

Why gamble on a launcher that can deliver 13 tonnes to orbit with design having a (demonstrated) 1 in 19 failure rate when you could have 15 tonnes on a vehicle that's already demonstrated however many flights (5? 20? 100?) that vehicle has already done.

My real concern for the SABRESkylon concept remains how you can collect expressions of interest in the project in a form that is legally binding, can be transferred to the mfg consortium and can be shown to funding organizations as a potential revenue stream. Solve that problem and large scale funding (and interest in joining a consortium) becomes much higher.

BTW The Channel Tunnel is operated by Eurotunnel. The actual "manufacturer" was the "Trans Marche Link" consortium

Any discussion around using the Tunnel as a model for how Skylon could develop should look at wheather TML made a profit (AFAIK they did) since they would be the equivalent of (to coin a name) "Skylon Enterprises Ltd."
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 12/01/2015 03:06 pm

While I agree Skylon would not be used as a bomber, we have to get our facts straight. ICBMs did not kill off the strategic nuclear bomber 50 years ago. Russia and the US still have strategic bombers today that carry nuclear weapons.
Then the question would then be how many current B52 and B2 missions are flying nuclear weapons?

My guess is few or none, just as the USN stopped carriers carrying nuclear bombs

How would anyone know as such information is no doubt classified so I don't see the point of asking.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 12/01/2015 07:12 pm
by the way, Reuters had a story on Skylon as well yesterday

http://www.reuters.com/article/2015/11/30/us-rocket-engine-space-plane-idUSKBN0TJ19U20151130
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 12/01/2015 08:42 pm
Skylon's biggest market potential is point-to-point transport. I know that's not how it's designed, but it dwarfs the orbital launch market (which they're probably going to lose to the likes of SpaceX and Blue Origin anyway).
Do not forget the potential market for point to point delivery of 200lb warheads. While it might be nice to imagine investors looking towards space, I'm sure investors BAE is looking at Skylon and thinking 'mach 5 cruise missile' or '150,000ft bomber'. If the engine works, and can be made to work on something a little more practical, like methane (which it supposedly can) then that is something they can sell to a lot of customers, whether the space business works out or not.

The Skylon C1 users manual had a suborbital deployment mode which could carry 30mt payloads and a while back in the thread I made the suggestion that the USAF could use that for delivering a bunch of their new High Speed Strike Weapons to  high mach removing the need for them to have rocket boosters, but apparently for Skylon D1 REL haven't worked out the rentry for that and the payload bay is no longer rated for that heavy a payload. But at those speeds a Skylon derived vehicle could delivery none ballistic munitions without every having to enter contested airspace.

If the engine works, and can be made to work on something a little more practical, like methane (which it supposedly can)
Do you have a source for that? To the best of my knowledge the cryogenic aspect is an essential part of the design, both as a form of stored energy (in addition to the calorific value) and as a heat sink


I modelled this stuff little a while back, if you're just interested in this as a hypersonic aircraft engine then I think you can run a Scimitar like engine ( i.e. 1:3 fuel air ratio) on a 40/60 methane/ammonia mix, which gives you a much denser fuel, but the performance drop kills SSTO and you are dealing with a gelled fuel.

New article on Skylon.

Interestingly, Mark Thomas emphasizes that the SABRE engine is highly scalable, and continues the trend of inviting the press to talk about vehicle concepts in addition to Skylon...

Quote
“This is a really versatile propulsion system that we’re developing. It is an air-breathing rocket engine that can go from zero to five times the speed of sound and for the space-access variant, 25 times the speed of sound, and has a huge range of operation. The other advantage of this engine is that it’s highly scaleable.”
The ability to up or down-size the concept is undoubtedly a trump card.

http://www.telegraph.co.uk/finance/newsbysector/industry/engineering/12023867/British-technology-company-to-transform-air-and-space-travel-with-pioneering-new-engine-design.html

It's interesting how Mark Thomas sounds almost like an enthusiastic commenter on this thread. I think to an extent as the former head of future programmes at Rolls Royce he's intimately aware of what RR has in development and with that in mind having come in to take charge of a company with a laser focus on space launch he's especially aware of the much broader capabilities of the technology.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 12/01/2015 09:41 pm
by the way, Reuters had a story on Skylon as well yesterday

http://www.reuters.com/article/2015/11/30/us-rocket-engine-space-plane-idUSKBN0TJ19U20151130

Quote
60 million pounds ($.4 million USD)
Quote
up to 20 times the speed of sound if it's going into orbit
Quote
high-vacuum braise
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Asteroza on 12/01/2015 10:55 pm
New article on Skylon.

Interestingly, Mark Thomas emphasizes that the SABRE engine is highly scalable, and continues the trend of inviting the press to talk about vehicle concepts in addition to Skylon...

Quote
“This is a really versatile propulsion system that we’re developing. It is an air-breathing rocket engine that can go from zero to five times the speed of sound and for the space-access variant, 25 times the speed of sound, and has a huge range of operation. The other advantage of this engine is that it’s highly scaleable.”
The ability to up or down-size the concept is undoubtedly a trump card.

http://www.telegraph.co.uk/finance/newsbysector/industry/engineering/12023867/British-technology-company-to-transform-air-and-space-travel-with-pioneering-new-engine-design.html

Scalable in what ways though?

REL is avoiding a subscale demonstrator due to fears of scaling effects for a full size Skylon. Does that imply a 1 MT payload small-Skylon is impractical, or simply undesired?

Skylon already needs a pretty hefty but otherwise conventional runway, so going larger seems possible but difficult. How would one implement a bigger Skylon? At some point would you need dedicated infrastructure for launch in some manner? Say, landing gear is rated for ferry MGTOW but not orbital mission MGTOW, so some sort of launch trolley/hovercraft assistively supporting the weight at the landing gear frame roots...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: mtakala24 on 12/01/2015 10:59 pm
by the way, Reuters had a story on Skylon as well yesterday

http://www.reuters.com/article/2015/11/30/us-rocket-engine-space-plane-idUSKBN0TJ19U20151130

Having followed Skylon's progress only sporadically during the last few years, is the article a good recap or does it miss any important details/developments?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 12/01/2015 11:17 pm
I think it is a rather good summary but with little technical detail. Are you planning to write an article on Skylon? if yes, I would advise you to talk with John, he's the one who knows Skylon stuff the most I guess.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 12/01/2015 11:32 pm
by the way, Reuters had a story on Skylon as well yesterday

http://www.reuters.com/article/2015/11/30/us-rocket-engine-space-plane-idUSKBN0TJ19U20151130

Having followed Skylon's progress only sporadically during the last few years, is the article a good recap or does it miss any important details/developments?
It misses out that the new engine design they plan to develop, SABRE 4, doesn't cool the air down to minus 150 degrees C only to 400K and thus doesn't need to bother with frost prevention while being twice as efficient.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 12/02/2015 12:14 am
I'm definetively not an expert, but with a 15 T payload, Couldn't skylon carry a weapon optimized for re-entry up to orbit, and release the warhead just above target?
True, but as others have pointed out it's a very expensive way to carry out this task and if you have the skills (and funding) to do it anyway you already have the means to carry much more cost effective forms of warfare.

I meant that it that it couldn't both be true the Skylon could be successful in providing point to point transport and at same time fail to provide the lowest priced orbital launch and that the logical conclusion of success at point to point transport is in the long term development of dedicated hypersonic air transport using the same Skylon derived technology which for the reasons stated means that it really can't be true that Sklyon derived systems could prove superior at revolutionising air travel but fail to be better at orbital launch than staged reusable rockets, i.e. the statement doesn't make any sense.

Yes I'd agree with that.  REL's focus has been orbital launch. It seems to believe they would succeed at something that was not their core focus, but fail at their core goal.

It could be true if Falcon ends up cheaper at a moderately high flight rate than Skylon does at a very high flight rate.  That doesn't seem especially likely to me, but we don't actually know yet...
Good point. But let's keep in mind the Skylon consortium will sell Skylons. It's up to the operators what the launch rate is

An if the Skylon operator is truly ruthless they will massively undercut SpaceX prices , drive them into bankruptcy and then raise their prices to cover the cost of launches and buying new Skylons.
It the ruthless, no prisoner approach to the space business.  ...
Of course, if a mystery launch provider could somehow do this, then SpaceX (backed by Google, or perhaps from constellation revenue) could do the same thing.

...except it's preposterous and clearly violates WTO rules, for either SpaceX or some mystery Skylon operator. Sounds like a very good way to lose billions of dollars for basically no gain (countries maintain independent launch capability for national security purposes, so one provider will never be able to totally drive everyone else out and develop a monopoly).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 12/02/2015 12:18 am
by the way, Reuters had a story on Skylon as well yesterday

http://www.reuters.com/article/2015/11/30/us-rocket-engine-space-plane-idUSKBN0TJ19U20151130

Quote
60 million pounds ($.4 million USD)
...
Did the UK just develop a serious inflation problem?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/02/2015 07:20 am
...except it's preposterous and clearly violates WTO rules, for either SpaceX or some mystery Skylon operator. Sounds like a very good way to lose billions of dollars for basically no gain (countries maintain independent launch capability for national security purposes, so one provider will never be able to totally drive everyone else out and develop a monopoly).
Thank you for noticing the difference between a launch vehicle manufacturer and a launch services provider

For ELV's this is a book keeping exercise but for Skylon there would indeed be a clear separation between the two.

The "National Security" "assured access" argument led to ULA being formed. Then you end up with gradually rising launch costs because the beast has to be fed.

An  early adopter could follow this strategy but maximizing profit during the window when they are a unique provider suggests they would go just below the market floor to get business.

In fact pretty much what SX has done.

However what really lowers cost is competition, so it's what happens when Skylon is sold to the second customer that things start to get interesting.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Archibald on 12/02/2015 02:42 pm
This has been discussed earlier in the thread - so Sabre 4 no longer care about frost control ? -
 see below (from the patent)

(http://i772.photobucket.com/albums/yy1/cacaprout1/precooler_zpsgkkwoyor.png)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Ravenger on 12/02/2015 03:11 pm
If I remember this correctly Sabre 4 has different combustion chambers for airbreathing and rocket modes, rather than the combined combustion chamber of Sabre 3. This adds weight, but means you don't have to cool the air as deeply, so you don't need the frost control mechanism.

It's also more fuel efficient so the extra weight is more than traded off by the performance increases.

In theory of course :)

It's deeply ironic that we finally found out how the top-secret frost-control system worked, only to find out at the same time that Sabre 4 doesn't need it.  ::)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Archibald on 12/02/2015 05:13 pm
Indeed, quite the irony. But if that helps them flying Skylons as soon as possible, I'm for it.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/02/2015 05:33 pm
Thank you for noticing the difference between a launch vehicle manufacturer and a launch services provider

There isn't a difference.  They are one in the same.   Space launch does not follow the aircraft manufacturer and airline COP.  And likely will never.   ILS is just a broker.  Arianespace is really an integrator (with falls under manufacturing).  And LSOC/USA still had to employ Rockwell/Boeing for shuttle integration/engineering.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/02/2015 05:42 pm

For ELV's this is a book keeping exercise but for Skylon there would indeed be a clear separation between the two.


Not a given.  There is no proof that it will happen.  Skylon likely will be too complex to be operated many
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 12/02/2015 10:52 pm
If I remember this correctly Sabre 4 has different combustion chambers for airbreathing and rocket modes, rather than the combined combustion chamber of Sabre 3. This adds weight, but means you don't have to cool the air as deeply, so you don't need the frost control mechanism.

It's also more fuel efficient so the extra weight is more than traded off by the performance increases.

In theory of course :)

It's deeply ironic that we finally found out how the top-secret frost-control system worked, only to find out at the same time that Sabre 4 doesn't need it.  ::)
I always thought the frost control that Sabre had allowed it to achieve an air breathing performance no one else could match. 

Does this now mean other companies could design and build their own design to match a Sabre engine, also would this mean the pre-cooler could be reduced in size enabling a reduction in weight and production costs.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 12/02/2015 11:01 pm
Thank you for noticing the difference between a launch vehicle manufacturer and a launch services provider

There isn't a difference.  They are one in the same.   Space launch does not follow the aircraft manufacturer and airline COP.  And likely will never.   ILS is just a broker.  Arianespace is really an integrator (with falls under manufacturing).  And LSOC/USA still had to employ Rockwell/Boeing for shuttle integration/engineering.

there is a difference in theory, and there is a difference for Skylon according with REL own plans. You might not like them, you might believe they are unrealistic and that "reality" today is different, but then again if anything that differs from how things are done today is unrealistic for the simple fact that they are not done today, why do you even bother about Skylon?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 12/02/2015 11:04 pm
If I remember this correctly Sabre 4 has different combustion chambers for airbreathing and rocket modes, rather than the combined combustion chamber of Sabre 3. This adds weight, but means you don't have to cool the air as deeply, so you don't need the frost control mechanism.

It's also more fuel efficient so the extra weight is more than traded off by the performance increases.

In theory of course :)

It's deeply ironic that we finally found out how the top-secret frost-control system worked, only to find out at the same time that Sabre 4 doesn't need it.  ::)
I always thought the frost control that Sabre had allowed it to achieve an air breathing performance no one else could match. 

Does this now mean other companies could design and build their own design to match a Sabre engine, also would this mean the pre-cooler could be reduced in size enabling a reduction in weight and production costs.

It was that kind of thinking and this post:
http://forum.nasaspaceflight.com/index.php?topic=36826.msg1449867#msg1449867

...that inspired my "buck your ideas up, China is coming" post on the last page! Just on the off chance someone from REL / BAE / ESA / Ariane is reading and would be inspired by my kick up the pants!  ;D
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 12/02/2015 11:19 pm
If I remember this correctly Sabre 4 has different combustion chambers for airbreathing and rocket modes, rather than the combined combustion chamber of Sabre 3. This adds weight, but means you don't have to cool the air as deeply, so you don't need the frost control mechanism.

It's also more fuel efficient so the extra weight is more than traded off by the performance increases.

In theory of course :)

It's deeply ironic that we finally found out how the top-secret frost-control system worked, only to find out at the same time that Sabre 4 doesn't need it.  ::)
I always thought the frost control that Sabre had allowed it to achieve an air breathing performance no one else could match. 

Does this now mean other companies could design and build their own design to match a Sabre engine, also would this mean the pre-cooler could be reduced in size enabling a reduction in weight and production costs.

REL's achievement lies in designing a thermodynamically more efficient engine cycle and building an ultralight heat exchanger capable of the task required, an incredibly difficult engineering task built on thirty years of experimentation, and hard fought experience. Other companies are free to try and replicate it but knowing how it works isn't the same as knowing how to build it. Plus it is patented.
Also it's not like nobody else has been trying to do this, the Japanese have been trying to build a liquid hydrogen precooled jet engine since the 90's i.e. Atrex, PCTJ.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 12/02/2015 11:50 pm
If I remember this correctly Sabre 4 has different combustion chambers for airbreathing and rocket modes, rather than the combined combustion chamber of Sabre 3. This adds weight, but means you don't have to cool the air as deeply, so you don't need the frost control mechanism.

It's also more fuel efficient so the extra weight is more than traded off by the performance increases.

In theory of course :)

It's deeply ironic that we finally found out how the top-secret frost-control system worked, only to find out at the same time that Sabre 4 doesn't need it.  ::)
I always thought the frost control that Sabre had allowed it to achieve an air breathing performance no one else could match. 

Does this now mean other companies could design and build their own design to match a Sabre engine, also would this mean the pre-cooler could be reduced in size enabling a reduction in weight and production costs.

REL's achievement lies in designing a thermodynamically more efficient engine cycle and building an ultralight heat exchanger capable of the task required, an incredibly difficult engineering task built on thirty years of experimentation, and hard fought experience. Other companies are free to try and replicate it but knowing how it works isn't the same as knowing how to build it. Plus it is patented.
Also it's not like nobody else has been trying to do this, the Japanese have been trying to build a liquid hydrogen precooled jet engine since the 90's i.e. Atrex, PCTJ.

Ok, but since it has been done - by three men and a dog - marvellous men though they are, it is do-able, so, I figure, someone else could do it.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 12/03/2015 03:17 am
I was wondering what the first Skylon should be called. I hope this is not too trivial for this forum.  Given the difficulties. I was thinking of e.g.

Dauntless
...or
Indomitable

But I am sure you can do better.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: TakeOff on 12/03/2015 07:42 am
I was wondering what the first Skylon should be called. I hope this is not too trivial for this forum.  Given the difficulties. I was thinking of e.g.

Dauntless
...or
Indomitable

But I am sure you can do better.
It will be named "Gorm".
This is England! No pompous transatlantic traitor colony who use false latin. Tables have switched, these are not the days of the Dreadnought. Actually, I predict it will be named "Muhammed" and that it will never fly.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/03/2015 09:01 am
There isn't a difference.  They are one in the same.   Space launch does not follow the aircraft manufacturer and airline COP.
Hello Jim. it's so rare to see you post to this thread.
For an ELV that basically follows the same flight path as an ICBM I'd agree there isn't.

One question I've always wondered about is how easy you could mount  warheads on a current generation LV and turn it back into an ICBM. My guess is pretty easily.  :(

"Concept of Operations" (I'm more used to ConOps myself) or "How we do 'things' with 'stuff' "  has changed over time and place.

In Europe it used to be thought the automobile would never be a mass transit device because "There are simply not enough people to train as chauffeurs"

During early aviation it was inconceivable that any pilot would have no ability to service their own engines, because they were so unreliable.

Likewise given that 70% of the Earth's surface is water  a segment of the aviation industry considered larger and larger seaplanes were the logical way to open up commercial aviation.

All of these COP's were either flat out wrong or shrunk to virtually nothing over time. People drive themselves, modern engines are reliable enough (and well enough instrumented) that failure is improbable and signal in advance and big jet powered sea planes never really happened (although I think they were rather beautiful).

Historically the bar to entry to the LV business has stopped any major shift in approach and the one attempt in the US to do so (STS) was so handicapped by funding and management decisions that it was amazing a design reached flight status and flew successfully.
Quote
And likely will never.
And that's where you start making assumptions.

BTW Shouldn't there be a noun at the end of that sentence?

Not a given.  There is no proof that it will happen.  Skylon likely will be too complex to be operated many
Now that sentence definitely needs an object at the end of it.  It's basically impossible to answer without one.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/03/2015 02:09 pm
The Skylon concept presents a freight company model, but the manual makes mention of Launch control, Facilities, Range Safety and Mission Control

Does anyone have a feel for how these would be sized in relation to those needed for current launch vehicles?
Keep in mind it is a UAV.

While I might expect to have such facilities I doubt they would be on the scale of any a conventional launch system.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hanelyp on 12/03/2015 03:55 pm
The Skylon concept presents a freight company model, but the manual makes mention of Launch control, Facilities, Range Safety and Mission Control

Does anyone have a feel for how these would be sized in relation to those needed for current launch vehicles?
To keep operations costs down you need to minimize the expense of ground facilities and crew relative to the number of vehicles flying.  There will be a massive reduction from STS in ground crew for a vehicle, as well as turn around time, or Skylon will be a failure economically.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Ravenger on 12/03/2015 04:18 pm
To keep operations costs down you need to minimize the expense of ground facilities and crew relative to the number of vehicles flying.  There will be a massive reduction from STS in ground crew for a vehicle, as well as turn around time, or Skylon will be a failure economically.

Skylon operation would be closer to the normal airport style of working with shared facilities between different carriers/operators

The airport and facilities including traffic control, range safety, etc. would probably be owned by a separate company, with the operators leasing hangars and facilities and paying fees for take off and landing slots, like how existing airports operate.

It'll be interesting to see how mission control is implemented as each mission profile would be unique to each Skylon launch. Perhaps mission control would be run by the space-port, with the help of operator specialists and representatives for each mission. 

Alternately if mission control is only a few people, then each carrier could have one, with spaceport traffic control just authorising take-offs and landings and parking/refuelling slots.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 12/04/2015 02:55 am
Or no one will buy a Skylon because they'll be taking a huge risk.

Reaction Engines and their partners will necessarily HAVE to operate Skylon for quite a while before they'll sell any.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 12/04/2015 04:12 am
Do you think 400 test flights is too few to prove out the design?  Or do you think the vehicle's cost profile is too front-heavy for the market?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/04/2015 07:09 am
To keep operations costs down you need to minimize the expense of ground facilities and crew relative to the number of vehicles flying.  There will be a massive reduction from STS in ground crew for a vehicle, as well as turn around time, or Skylon will be a failure economically.
True.

Skylon has been designed by a small team. As such the various systems are much better integrated in terms of how margins are traded off. Shuttle had something like 60 off tanks and 30 separate fluids, all with it's own little team to fill/fix/drain/monitor its operation.

Skylon has 3 core (LO2,LH2, cooling water) or 4 if they go with a hydraulic system and not EMA's (now flight proven on Vega for main engine 1st stage use).

Shuttle development and maintenance offers many lessons to anyone planning to build an RLV and NASA has documented a lot of those in various work, especially in the team lead by Edward Zapata.

I'm quite sure REL have studied most of it closely.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 12/04/2015 09:20 am
I'm definetively not an expert, but with a 15 T payload, Couldn't skylon carry a weapon optimized for re-entry up to orbit, and release the warhead just above target?
True, but as others have pointed out it's a very expensive way to carry out this task and if you have the skills (and funding) to do it anyway you already have the means to carry much more cost effective forms of warfare.

I meant that it that it couldn't both be true the Skylon could be successful in providing point to point transport and at same time fail to provide the lowest priced orbital launch and that the logical conclusion of success at point to point transport is in the long term development of dedicated hypersonic air transport using the same Skylon derived technology which for the reasons stated means that it really can't be true that Sklyon derived systems could prove superior at revolutionising air travel but fail to be better at orbital launch than staged reusable rockets, i.e. the statement doesn't make any sense.

Yes I'd agree with that.  REL's focus has been orbital launch. It seems to believe they would succeed at something that was not their core focus, but fail at their core goal.

It could be true if Falcon ends up cheaper at a moderately high flight rate than Skylon does at a very high flight rate.  That doesn't seem especially likely to me, but we don't actually know yet...
Good point. But let's keep in mind the Skylon consortium will sell Skylons. It's up to the operators what the launch rate is

An if the Skylon operator is truly ruthless they will massively undercut SpaceX prices , drive them into bankruptcy and then raise their prices to cover the cost of launches and buying new Skylons.
It the ruthless, no prisoner approach to the space business.  ...
Of course, if a mystery launch provider could somehow do this, then SpaceX (backed by Google, or perhaps from constellation revenue) could do the same thing.

...except it's preposterous and clearly violates WTO rules, for either SpaceX or some mystery Skylon operator. Sounds like a very good way to lose billions of dollars for basically no gain (countries maintain independent launch capability for national security purposes, so one provider will never be able to totally drive everyone else out and develop a monopoly).
WTO take years to sort out. You only threaten WTO when you want to kick the bucket down the road. An I mention that the military might choose security concerns over using the cheapest system. They done it before and Musk has plenty of time and money to build up a protection network inside them military like Boeing and co have done befor Skylon flies.

The formula changes as private industry builds itself up, if private industry flock to skylon there may simply not be the money to keep up another system flying.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 12/04/2015 09:27 am
I was wondering what the first Skylon should be called. I hope this is not too trivial for this forum.  Given the difficulties. I was thinking of e.g.

Dauntless
...or
Indomitable

But I am sure you can do better.
Now we get onto the important subject.  ;D

Thunderbird
or
Anastasia (name after Dan dare ship)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 12/04/2015 09:30 am
I was wondering what the first Skylon should be called. I hope this is not too trivial for this forum.  Given the difficulties. I was thinking of e.g.

Dauntless
...or
Indomitable

But I am sure you can do better.
Now we get onto the important subject.  ;D

Thunderbird
or
Anastasia (name after Dan dare ship)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Ravenger on 12/04/2015 11:29 am
I was wondering what the first Skylon should be called. I hope this is not too trivial for this forum.  Given the difficulties. I was thinking of e.g.

Dauntless
...or
Indomitable

But I am sure you can do better.

Fireflash because it sort of resembles it  :D

http://thunderbirds.wikia.com/wiki/Fireflash

I hope the registation or serial number is 007, as it was designed by Mr. Bond.  ::)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 12/04/2015 01:37 pm
It's interesting to think that being able to have a name is one aspect of re-usability.   Why name something that is destroyed the first time you use it?

How powerful names like "Enterprise"  or "Ark Royal" or "Illustrious" are!  It will be sad if Skylons only get numbers.   I hope they get named and that the names live again and again like ship names do.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 12/04/2015 01:46 pm
Or no one will buy a Skylon because they'll be taking a huge risk.

Reaction Engines and their partners will necessarily HAVE to operate Skylon for quite a while before they'll sell any.

Of course: they plan a 200 flights test programme. MORE than practically any other orbital launch vehicle to date, afaik.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/04/2015 02:27 pm

Skylon operation would be closer to the normal airport style of working with shared facilities between different carriers/operators

The airport and facilities including traffic control, range safety, etc. would probably be owned by a separate company, with the operators leasing hangars and facilities and paying fees for take off and landing slots, like how existing airports operate.

It'll be interesting to see how mission control is implemented as each mission profile would be unique to each Skylon launch. Perhaps mission control would be run by the space-port, with the help of operator specialists and representatives for each mission. 

Alternately if mission control is only a few people, then each carrier could have one, with spaceport traffic control just authorising take-offs and landings and parking/refuelling slots.

A lot of unsupported conjecture and wrong conclusions.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/04/2015 02:28 pm

While I might expect to have such facilities I doubt they would be on the scale of any a conventional launch system.


They very likely will be on the same scale.  Hangars, propellant storage, payload processing facilities would be the same.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/04/2015 02:32 pm

there is a difference in theory, and there is a difference for Skylon according with REL own plans. You might not like them, you might believe they are unrealistic and that "reality" today is different, but then again if anything that differs from how things are done today is unrealistic for the simple fact that they are not done today, why do you even bother about Skylon?

You are right.  I shouldn't bother since there is too much nonsense, unsupported conjecture and flat out just wrong statements on this thread.  Much of it should be in the scifi section because it isn't reality or come close to it.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/04/2015 02:34 pm
REL's achievement lies in designing a thermodynamically more efficient engine cycle

What "achievement"?  They yet to build one much operate one.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/04/2015 02:36 pm
The Skylon concept presents a freight company model, but the manual makes mention of Launch control, Facilities, Range Safety and Mission Control

Does anyone have a feel for how these would be sized in relation to those needed for current launch vehicles?



the same.  expendable vs reusable doesn't really change the flight support facilities.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 12/04/2015 02:57 pm

While I might expect to have such facilities I doubt they would be on the scale of any a conventional launch system.

They very likely will be on the same scale.  Hangars, propellant storage, payload processing facilities would be the same.

Given that Skylon doesn't have to be assembled at the site or transported there by machines, is that certain?  At the very least doesn't one need a lot less people and/or equipment?

Presumably it also needs quite a lot less liquid oxygen storage than a conventional launcher might.

On the other hand, if there is a high flight rate (in surges perhaps) then one might need much more propellant storage than a conventional launch site..
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 12/04/2015 03:51 pm
REL's achievement lies in designing a thermodynamically more efficient engine cycle

What "achievement"?  They yet to build one much operate one.
Did I say they had built one?
 I said they had designed an engine cycle and built a heat exchanger which they indisputably have done and which multiple institutions such as ESA, AFRL, DSTL, UKSA, BAE and DLR seem to recognize as an achievement worth noting and/or funding, you may not consider it an achievement warranting praise but clearly these things have been achieved by the company and praise is not a necessary condition of achievement.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 12/04/2015 03:56 pm

there is a difference in theory, and there is a difference for Skylon according with REL own plans. You might not like them, you might believe they are unrealistic and that "reality" today is different, but then again if anything that differs from how things are done today is unrealistic for the simple fact that they are not done today, why do you even bother about Skylon?

You are right.  I shouldn't bother since there is too much nonsense, unsupported conjecture and flat out just wrong statements on this thread.  Much of it should be in the scifi section because it isn't reality or come close to it.

Good, I'm glad we agree to disagree. Now it would be very kind of you if you could let us continuing our "nonsense conjectures" without further poisoning the discussion..
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/04/2015 03:56 pm
Did I say they had built one?
 I said they had designed an engine cycle and built a heat exchanger which they indisputably have done and which multiple institutions such as ESA, AFRL, DSTL, UKSA, BAE and DLR seem to recognize as an achievement worth noting and/or funding, you may not consider it an achievement warranting praise but clearly these things have been achieved by the company and praise is not a necessary condition of achievement.

There are many designs that have never left the factory or even drawing stage.  There aren't "off the drawing board" ceremonies, there are rollout ceremonies.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Archibald on 12/04/2015 04:24 pm
It's interesting to think that being able to have a name is one aspect of re-usability.   Why name something that is destroyed the first time you use it?

How powerful names like "Enterprise"  or "Ark Royal" or "Illustrious" are!  It will be sad if Skylons only get numbers.   I hope they get named and that the names live again and again like ship names do.


Just name them from all those battleships Britain build between 1890 and 1940. They build a crapton of them.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 12/04/2015 04:29 pm
Unless someone has a time machine, any thread that’s discussing events a decade out or more is going to have to humor both optimists and pessimists arguing their cases. But without details or insights this back and forth is dull, dull, dull.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/04/2015 04:33 pm

Good, I'm glad we agree to disagree. Now it would be very kind of you if you could let us continuing our "nonsense conjectures" without further poisoning the discussion..

No, I will continue to point out the nonsense
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/04/2015 04:36 pm

Given that Skylon doesn't have to be assembled at the site or transported there by machines, is that certain?  At the very least doesn't one need a lot less people and/or equipment?

Presumably it also needs quite a lot less liquid oxygen storage than a conventional launcher might.

On the other hand, if there is a high flight rate (in surges perhaps) then one might need much more propellant storage than a conventional launch site..

Still needs a lot of LH2, so the amount of LOX doesn't matter.  Still need a hangar much like the shuttle.  Still need payload processing area.  So look at Spacex pad but without the erector.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 12/04/2015 05:08 pm
One of the phrases used in connection with Skylon that raises eyebrows is ‘aircraft-like operations’.

Optimists picture a Skylon landing - much like a passenger jet - someone kicking the tires, filling up the tanks, loading a new payload, and then sending it back into orbit. And of course cashing the check.

For this to happen REL will have to accomplish a second breakthrough in space technology in addition to air breathing propulsion: a never-before-seen ultra low maintenance spacecraft (and all associated systems: RCS, OMS, TPS, landing gear/braking, aerosurfaces/actuators, etc.)

REL clearly expect to achieve this, hence the 200 flight test plan. But it’s not been done before. You can flip the reusability argument on its head and call expendable vehicles ‘maintenance free’. Sitting here in 2015 we don’t know what infrastructure will be needed to keep Skylon flying. But we do know it’s more than throwaway rockets need :-)

The maintenance of a passenger jet is low because much of the time it’s earning money it’s at cruise. And that’s a very benign environment - not that much different to being in the hangar. But this will not be the case for Skylon: ironically it will not be aircraft-like.

During the test flights REL will learn which systems need to be maintained with what frequency. If they get it all right first try, then the aircraft infrastructure analogy holds. Minimal inspection and maintenance will be done at the launch site (so it will require less pad infrastructure than STS.) And Skylon is only moved back to the assembly facility for major overhauls.

But realistically, we can’t expect them to get it all right first try - some system will have teething trouble and need to be inspected/tweaked/swapped out. And now the launch facility begins to look more and more like the factory.

Can we predict if Skylon will be gas-and-go for 200 flights, or need to be rebuilt every flight? Nope, not yet.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 12/04/2015 05:10 pm
they plan a 200 flights test programme.

~400, not 200.  Two vehicles, two years.  One vehicle doing envelope exploration and about 30 abort tests, the other doing 204 orbital launches to demonstrate the specified service lifetime (200 flights, plus the 4 test flights each unit undergoes before delivery).

I believe this was subsequent to the maybe-not-orbital boilerplate vehicle tests.

There may be newer information, but I don't recall seeing it.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 12/04/2015 05:17 pm
Right, ~400. But frankly this plan only tells me their heart is in the right place. Not that they can achieve it.

They could just as easily say ~1000 to cover even more of the edge/abort cases. Or ~100 which would give them parity statistics with other vehicles.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 12/04/2015 06:48 pm

Good, I'm glad we agree to disagree. Now it would be very kind of you if you could let us continuing our "nonsense conjectures" without further poisoning the discussion..

No, I will continue to point out the nonsense

if you think it adds to the discussion, feel free. But I think is more poisonous than else.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 12/04/2015 06:50 pm
they plan a 200 flights test programme.

~400, not 200.  Two vehicles, two years.  One vehicle doing envelope exploration and about 30 abort tests, the other doing 204 orbital launches to demonstrate the specified service lifetime (200 flights, plus the 4 test flights each unit undergoes before delivery).

I believe this was subsequent to the maybe-not-orbital boilerplate vehicle tests.

There may be newer information, but I don't recall seeing it.

well, even better then. Waiting for investors...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 12/04/2015 09:24 pm
Did I say they had built one?
 I said they had designed an engine cycle and built a heat exchanger which they indisputably have done and which multiple institutions such as ESA, AFRL, DSTL, UKSA, BAE and DLR seem to recognize as an achievement worth noting and/or funding, you may not consider it an achievement warranting praise but clearly these things have been achieved by the company and praise is not a necessary condition of achievement.

There are many designs that have never left the factory or even drawing stage.  There aren't "off the drawing board" ceremonies, there are rollout ceremonies.

Absolutely true and if you've been reading the thread you'll have seen that I gave odds that it was more likely than not that Skylon won't be built but it's clearly not true that theoretical work in science and engineering is never celebrated.

One of the phrases used in connection with Skylon that raises eyebrows is ‘aircraft-like operations’.

Optimists picture a Skylon landing - much like a passenger jet - someone kicking the tires, filling up the tanks, loading a new payload, and then sending it back into orbit. And of course cashing the check.

For this to happen REL will have to accomplish a second breakthrough in space technology in addition to air breathing propulsion: a never-before-seen ultra low maintenance spacecraft (and all associated systems: RCS, OMS, TPS, landing gear/braking, aerosurfaces/actuators, etc.)

REL clearly expect to achieve this, hence the 200 flight test plan. But it’s not been done before. You can flip the reusability argument on its head and call expendable vehicles ‘maintenance free’. Sitting here in 2015 we don’t know what infrastructure will be needed to keep Skylon flying. But we do know it’s more than throwaway rockets need :-)

The maintenance of a passenger jet is low because much of the time it’s earning money it’s at cruise. And that’s a very benign environment - not that much different to being in the hangar. But this will not be the case for Skylon: ironically it will not be aircraft-like.

During the test flights REL will learn which systems need to be maintained with what frequency. If they get it all right first try, then the aircraft infrastructure analogy holds. Minimal inspection and maintenance will be done at the launch site (so it will require less pad infrastructure than STS.) And Skylon is only moved back to the assembly facility for major overhauls.

But realistically, we can’t expect them to get it all right first try - some system will have teething trouble and need to be inspected/tweaked/swapped out. And now the launch facility begins to look more and more like the factory.

Can we predict if Skylon will be gas-and-go for 200 flights, or need to be rebuilt every flight? Nope, not yet.

Keep in mind that there is a paper stating the intention that the first tranche of Skylon production after the test programme is sold expensively to only experienced institutional operators (as Jim says at first very few organisations will have the know how to operate Skylon)  to allow for the proper commercial  maintenance and flight operations procedures to be developed and the initial operations feedback to feed into the second tranche of production which can be sold at a more affordable price to to a broader range of commercial operators along side a package of operational knowledge and maintenance. I would assume the 2 day turn around is something to be available once the broad commercial availability stage has been reached.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/05/2015 12:24 am
Or no one will buy a Skylon because they'll be taking a huge risk.

Reaction Engines and their partners will necessarily HAVE to operate Skylon for quite a while before they'll sell any.

Of course: they plan a 200 flights test programme. MORE than practically any other orbital launch vehicle to date, afaik.
He means REL selling launches after the 400 flight test programme (on 2 vehicles).

Note that The Aerospace Corporations  "3/8" rule that a failure within 3 launches (of an ELV)  is usually a design failure, within 8 it's probably a materials failure
They very likely will be on the same scale.  Hangars, propellant storage, payload processing facilities would be the same.
Actually given the size of the vehicle and the tanks I never expected them to be smaller.

However you missed out "Launch Control, Range Safety and Mission control"

I expect launch control to be much smaller given the higher structural margins and the underlying assumption that Skylon will work, rather than something that's a hairs breadth away from falling apart.

I would expect Range Safety to be autonomous on the vehicle. with engine shut down and propellant dumping ( no self destruct charges) to be SOP.

Mission Control? Isn't that what happens in an airport Control Tower? Shared across all vehicles using the runway.

So look at Spacex pad but without the erector.
The word you're looking for is "runway."  :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 12/05/2015 01:28 am
I mean selling launches /before/ all orbital launches have been completed.

Just 2 years of flight testing for 400 flights is VERY optimistic, as we can see from SpaceShipTwo and other reusable test-bed vehicles.

And yes, I do think that such expensive vehicles will be a hard sell, especially with the significant ground support equipment that will be necessary.

There will be a lot of pressure by investors to get earlier income. That's why I think that if Skylon ever happens, Reaction Engines will be initially operating Skylon for customer launches (during the "test program," if you like). And at that point, it'd be really tempting to just continue operating, since they'll already have the infrastructure in place.

And of course, customers of Skylon would know this. That's part of why I am skeptical of the "just sell Skylons to people, and ignore the actual launch market." If Skylon ever happens, I really doubt that's how it will work.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/05/2015 07:31 am
I mean selling launches /before/ all orbital launches have been completed.

Just 2 years of flight testing for 400 flights is VERY optimistic, as we can see from SpaceShipTwo and other reusable test-bed vehicles.
IE for a piloted, 2 stage passenger carrying vehicle programme where there is only 1 test vehicle in the programme.

Does that really sound like a fair comparison to you?

For an uncrewed, non passenger carrying vehicle (to begin with) with 2 development vehicles and being able to draw on roughly 100 years of flight test protocols I think the situation is much more favorable. Skylon is big and it's speed range is wide but it's aerodynamics are relatively (no "shuttle cock" re configurations) simple. It's statically stable (something Shuttle was not) and a great deal more is known about shocks on (and in) inlets since the the days Lockheed flew 66 flights to calibrate the SR71 inlets. I'm not sure how many flights Concorde or the Tu144 took to set their inlets up.
Quote
And yes, I do think that such expensive vehicles will be a hard sell, especially with the significant ground support equipment that will be necessary.
What specifically are you talking about?

Modern aircraft SOP is to fly with extensive servicing data being recorded (and in the case of some engines being transmitted to a central station while in flight) to monitor off line. That's been happening for 40+ years.

Large aircraft operations since 1954 (first flight of the C130 Hercules) or 1968 (first flight of C5A Galaxy), along with the Shuttle history have taught many lessons on operations & servicing, many of which can (and will) be incorporated before  Skylon is built That's a minimum 47 years of flight and maintenance experience (of large aircraft) to draw on.

In contrast the servicing procedures for any two stage vehicle with any degree of reuse are still being worked out, since the last 2 stage commercial (reusable) aircraft system flew in the 1930's. That puts SS2 about 75 years behind the fixed wing aircraft field in practice. Since no one's done VTO reuse (except in helicopters) SX will start from scratch.
Quote
There will be a lot of pressure by investors to get earlier income. That's why I think that if Skylon ever happens, Reaction Engines will be initially operating Skylon for customer launches (during the "test program," if you like). And at that point, it'd be really tempting to just continue operating, since they'll already have the infrastructure in place.
And yet Airbus did not do this (and AFAIK no other large passenger mfg in China or Russia has done this either).
BTW You're mistaking revenue for return on their investment. The classic way to realize ROI in modern times has been through an IPO. Outright Skylon sales would increase initial offer share price as there is solid potential for share dividends, unlike say Facebook, who's launch P/E ratio was in fractions of a century.

Quote
And of course, customers of Skylon would know this. That's part of why I am skeptical of the "just sell Skylons to people, and ignore the actual launch market." If Skylon ever happens, I really doubt that's how it will work.
Yes we can really see your doubts. :(

There are 3 ways you can solve a  problem.

Create a design, then find materials to implement it.

Evolve a design based on a fairly good knowledge of a materials strengths and weaknesses.

Build a vehicle like previous ones and try and "fix" it after you've built it to meet new more demanding criteria.

I'll leave you decide which RLV's fit in which category and what level of risk each approach has in reaching your end goal.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Archibald on 12/05/2015 01:05 pm
The fact is that Skylon  cryogens propellants, unpiloted mode,3 miles long take-off run and very high takeoff speed - all forbbide access to any airport. The FAA will never certify Skylon for LAX, JFK or Roissy CDG or Heathyrow. Just sayin'

Which doesn't mean Skylon is unseful. We still need a SSTO to lower the cost of a pound per orbit.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 12/05/2015 01:09 pm
I mean selling launches /before/ all orbital launches have been completed.

Just 2 years of flight testing for 400 flights is VERY optimistic, as we can see from SpaceShipTwo and other reusable test-bed vehicles.
IE for a piloted, 2 stage passenger carrying vehicle programme where there is only 1 test vehicle in the programme....
And I see you ignored the "and other reusable test-bed vehicles."
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/05/2015 05:46 pm
And I see you ignored the "and other reusable test-bed vehicles."
I presume you're talking about Grasshopper and SX's efforts here, or did you have some other test bed in mind?

So we've gone from the nearest winged to an attempted VTOL testbed.

A configuration that was guaranteed to have control issues from the start. It's no accident that all the plug nozzle based designs of Philip Bono in the 60's and the planned DC-1 were all kind of squat, since high aspect ratio designs, IE all ELVs were expected to be "floppy" and difficult to control.

Turned out they were right, even with 21st century computer speeds and program sizes.

That comes under the heading of "Starting with a design and trying to fix it." May be possible, may not be, but you can't put research on a clock.

SX are getting better at it but it's taken them a long time to do so.

SX are true pioneers and their heroic efforts to make this landing mode work are (I suspect) under appreciated. Slosh loads, deck winds, a landing pad that can fall or rise several meters. These are just a few issues the team has to contend with.

The fact is that Skylon  cryogens propellants, unpiloted mode,3 miles long take-off run and very high takeoff speed - all forbbide access to any airport. The FAA will never certify Skylon for LAX, JFK or Roissy CDG or Heathyrow. Just sayin'
People have been talking about Methane and LH2 for passenger aircraft since the 1970's, and a ferry mode Skylon will be 160 tonnes lighter with a much shorter takeoff run. Landing it will have neither on board cryogens nor high landing speed. In fact the key issues for an existing airport are likely to be it's a UAV and it's going to loud on takeoff.

BTW the FAA's writ does not run to France or the UK. And if it's not built in the US Skylon will not need their permission to operate in those airports to do so. Just saying'
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 12/05/2015 10:14 pm
Just so we're clear, it was never the intent to operate Skylon from an existing airport.  Emergencies are potentially a different matter, and if you really don't want liquid hydrogen on site, or you don't want the engines lit for the takeoff, you could always tow it.  But the usual mode of operation would be from a dedicated spaceport.

Just 2 years of flight testing for 400 flights is VERY optimistic, as we can see from SpaceShipTwo and other reusable test-bed vehicles.

If I'm not mistaken, this would be after the boilerplate prototype testing to ensure the system works.  It would be in large part a certification test series similar to what an airliner would go through.

(Also, it wasn't strictly two years - just less than three.)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 12/06/2015 12:28 am
Just so we're clear, it was never the intent to operate Skylon from an existing airport.  Emergencies are potentially a different matter, and if you really don't want liquid hydrogen on site, or you don't want the engines lit for the takeoff, you could always tow it.  But the usual mode of operation would be from a dedicated spaceport.
So customers would not only have to pay for their own Skylon or two, the ground support equipment required for it, payload processing building, but also a dedicated airport? Sounds like any possible payoff is further and further away for their potential customers. Since RE will need all this stuff (perhaps minus the payload processing) anyway just to prove out Skylon, they'll have a super easy opportunity to just start launching payloads themselves... (Which is fine with me, by the way.) It seems quite likely they'd be stuck in a situation where they paid for almost all the equipment needed to launch payloads themselves, but without being able to convince anyone to build a dedicated airport and buy all the ground support equipment and the Skylons needed to start service.

...Of course, I doubt they'd be stuck in that situation, since I'm sure they'd realize it before anything like a prototype flies.

Quote
Just 2 years of flight testing for 400 flights is VERY optimistic, as we can see from SpaceShipTwo and other reusable test-bed vehicles.

If I'm not mistaken, this would be after the boilerplate prototype testing to ensure the system works.  It would be in large part a certification test series similar to what an airliner would go through.

(Also, it wasn't strictly two years - just less than three.)
I thought the 400 flights info comes from before they planned the boilerplate prototype?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 12/06/2015 12:40 am
While there are many unknowns with Skylon, one pretty safe bet is as follows: If it ever launches payloads to orbit, it will launch them from Kourou and return there. If in doubt, it's better to think of Skylon as currently spec'd by REL is a spacecraft, not an aircraft.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Impaler on 12/06/2015 05:25 am
If 400 test flights are planned then it would be a crying shame to haul 6,000 mt of dummy payloads to orbit.  After say a dozen successes you might as well start using all that capacity and stimulating the market with a low cost to orbit so that your potential vehicle customers actually SEE the huge demand bubbling up that would be necessary to justify purchasing a vehicle.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 12/06/2015 12:34 pm
I thought it might be a good idea to repost some of the relevant papers given the current topics of conversation.
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Ric Capucho on 12/06/2015 12:42 pm
If 400 test flights are planned then it would be a crying shame to haul 6,000 mt of dummy payloads to orbit.  After say a dozen successes you might as well start using all that capacity and stimulating the market with a low cost to orbit so that your potential vehicle customers actually SEE the huge demand bubbling up that would be necessary to justify purchasing a vehicle.


Good point.

I'd expect dummy payloads for the first couple of Skylon test flights, and then deeply discounted commercial payloads for each subsequent flight, with the price discount ever reducing as the vehicle is proven and risk of loss is reduced. Then once the 200+ flight testing period draws to a close, the final operator of the now fully tested vehicles will look in vain for anything remaining on the ground still left to be launched.

What then? Launch what exactly into LEO? Rocks?

That's the achilles heel of both the Skylon commercial proposition and also SpaceX: without a Mars or Lunar program or some other pressing *need* to launch lots and lots of stuff into orbit, then both systems are going to be spending most of their time on the ground. Granted SpaceX has a Mars program on the drawing board (but I'm sceptical that even Elon and his friends have deep enough pockets to pay for it) so they're at least on paper providing their own pressing need for a reusable launch system. But Skylon's first operator? What's the pressing need for them? And can they cover the huge opportunity costs whilst a Skylon or two sit on the ground with nothing to launch?

This is where the infamous airliner comparison quickly falls apart: any airliner spends a large proportion of its time in the air... it'd better at those capital costs. And if not, it's soon returned to the leasing company after the airline goes bankrupt.

I personally would *love* Skylon to fly, but I greatly fear for the first commercial operator. "Build it, and they will come" is a fallacy that engineering-first companies fall for time and again. The Brits have a rich history of that, but I deleted the long list of examples that spring to my mind because I don't want to distract anyone from my point. But there is one sector with deep pockets where Skylon has a hope: first they'll need to paint it olive green; and then they'll have to weaponise it.

Cue the rush of SpaceX amazing peoples, Skylon amazing peoples and anti-military establishment types. (Yawn) Sticks and stones...

Ric
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/06/2015 02:19 pm

1.  I expect launch control to be much smaller given the higher structural margins and the underlying assumption that Skylon will work, rather than something that's a hairs breadth away from falling apart.

2.  I would expect Range Safety to be autonomous on the vehicle. with engine shut down and propellant dumping ( no self destruct charges) to be SOP.

3.  Mission Control? Isn't that what happens in an airport Control Tower? Shared across all vehicles using the runway.

So look at Spacex pad but without the erector.
4.  The word you're looking for is "runway."  :)

1.  No, LCC manning has nothing to with structural or operational margins.   Personnel are assigned by systems to manage.

2.  Still need to manage the range regardless of range safety methods.

3.  No.  That is the range control center.  The closest thing analogous wise would be the airline operations center, which are not typically at airports.  Mission control takes over after launch

4.  No, it would be the ramp at the terminal, which would be like the Spacex pad (hangar, prop storage, fueling area, payload facility, etc)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: banjo on 12/06/2015 03:34 pm
Quote from: Spaceflight vol 58, p26
[reporting on IAC 2015]... the new head of Arianspace, Stephane Israel, said he had not heard of Reaction Engines or the Skylon concept.

a strange marketing ploy to pretend have poor knowledge of one's industry.   
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 12/06/2015 05:43 pm
I thought the 400 flights info comes from before they planned the boilerplate prototype?

The idea of boilerplate Y-plane testing feeding into production prototype testing appears in the earliest image of REL's website on archive.org, from December 2003.  Mark Hempsell referenced the 400-flight test programme last June (specifically, he confirmed that it's part of the development budget, and always has been).  So no.

Best recent description of the test programme I can find is here (http://forum.nasaspaceflight.com/index.php?topic=24621.msg893482#msg893482).

Quote
The qualification flight test programme has two production prototypes (there are also two earlier full scale development vehicles which are probably not orbital).

...

Back in 2012, Hempsell also stated that they hoped to fly as many as 16 ISS missions during the test programme.  So apparently they didn't want to just launch a bunch of dummy payloads either...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Archibald on 12/06/2015 06:36 pm
There was a paper back then analyzing possible relationships between Skylon and ISS. I have it somewhere on my HD - it is certainly available on REL website.
I think their conclusion was that 16 Skylon flight would probably be totally overkill for the ISS. The logistic need is just not there.
The ISS uses to be on a "diet" regime of Progress, ATV, HTV, MPLM and the likes. Skylon logistic-rich regime would make it "obese".
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/06/2015 10:14 pm

1.  Would that be covered by ATC?

2.  Do you think the prop storage and fueling area are likely to be a spaceport facility? does the decoupling of fueling from launch give any benefits in terms of reducing the complexity of the launch process. Any benefits in terms of the size of the range control staff?


1.  No, just as ATC doesn't cover the area around an airport

2.  Range control staff is independent of the vehicle type and the ground support equipment.  That is launch control staff
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 12/06/2015 11:52 pm
If 400 test flights are planned then it would be a crying shame to haul 6,000 mt of dummy payloads to orbit.  After say a dozen successes you might as well start using all that capacity and stimulating the market with a low cost to orbit so that your potential vehicle customers actually SEE the huge demand bubbling up that would be necessary to justify purchasing a vehicle.


Good point.

I'd expect dummy payloads for the first couple of Skylon test flights, and then deeply discounted commercial payloads for each subsequent flight, with the price discount ever reducing as the vehicle is proven and risk of loss is reduced. Then once the 200+ flight testing period draws to a close, the final operator of the now fully tested vehicles will look in vain for anything remaining on the ground still left to be launched.

What then? Launch what exactly into LEO? Rocks?

That's the achilles heel of both the Skylon commercial proposition and also SpaceX: without a Mars or Lunar program or some other pressing *need* to launch lots and lots of stuff into orbit, then both systems are going to be spending most of their time on the ground. Granted SpaceX has a Mars program on the drawing board (but I'm sceptical that even Elon and his friends have deep enough pockets to pay for it) so they're at least on paper providing their own pressing need for a reusable launch system. But Skylon's first operator? What's the pressing need for them? And can they cover the huge opportunity costs whilst a Skylon or two sit on the ground with nothing to launch?

This is where the infamous airliner comparison quickly falls apart: any airliner spends a large proportion of its time in the air... it'd better at those capital costs. And if not, it's soon returned to the leasing company after the airline goes bankrupt.

I personally would *love* Skylon to fly, but I greatly fear for the first commercial operator. "Build it, and they will come" is a fallacy that engineering-first companies fall for time and again. The Brits have a rich history of that, but I deleted the long list of examples that spring to my mind because I don't want to distract anyone from my point. But there is one sector with deep pockets where Skylon has a hope: first they'll need to paint it olive green; and then they'll have to weaponise it.

Cue the rush of SpaceX amazing peoples, Skylon amazing peoples and anti-military establishment types. (Yawn) Sticks and stones...

Ric
Agreed. This is also why SpaceX is branching out to building and operating a comm satellite constellation. It gives their RLV (partial or full) something to justify its existence.

Skylon really needs something like that, too. I'm hopeful they'll find something other than just using Skylon as a bomber.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/07/2015 12:00 am

By decoupling the choreography of disconnections and releases, and by slowing the actual launch do you think the horizontal take-off concept have the potential to drastically simplify the launch sequence, or would it be only marginal, or make no significance difference? In addition by being dynamically stable and having a variety of intact abort options, does the Skylon concept have the potential to allow the launch control centre be scaled down? by how much?


not by much

https://blogs.nasa.gov/spacex/2014/09/21/mission-and-launch-control-centers-across-the-country/
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 12/07/2015 04:32 am
Changing up the angle a bit, why don't airliners require the same level of ground control attention as rockets, and how can (or why can't) Skylon move in that direction?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hanelyp on 12/07/2015 06:43 am
Changing up the angle a bit, why don't airliners require the same level of ground control attention as rockets, and how can (or why can't) Skylon move in that direction?
A lot of that has to do with system failure rate and ability to survive failures.  And airliners got there by flying a lot, building a knowledge base of how the systems can break down, and how the breakdowns can be prevented, predicted, or worked around.  A vehicle that is flown once and thrown away will never have that same reliability.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/07/2015 01:21 pm

I don't understand how your reference to a VTOL would help me to understand your answer -

It has nothing to do with orientation of takeoff or landing, it is the systems in the vehicle.  Skylon is going to have systems and operations that are similar to other launch vehicles that need monitoring prelaunch, like the loading of the propellants.  The example shown is a launch control center for a vehicle that both uses some of the latest technology.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/07/2015 01:30 pm
Changing up the angle a bit, why don't airliners require the same level of ground control attention as rockets, and how can (or why can't) Skylon move in that direction?

Because:
A.  Airliners have multiple back systems and also have the ability to have multiple abort modes.  Also, they have the ability to operate in a degraded mode.

b.  Jet engines are not working at the edge and they can contain a destructive failure or even fall off.

c.  An airliner fully fueled and ready to fly can sit on the ramp almost indefinitely.  A vehicle that uses cryogenics and hygols has to be monitored. 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Ravenger on 12/07/2015 02:05 pm

Because:
A.  Airliners have multiple back systems and also have the ability to have multiple abort modes.  Also, they have the ability to operate in a degraded mode.


I imagine Skylon will have some level of redundant systems. Skylon is also intended to have multiple abort modes. The runway length is designed for take-off aborts, the brakes are water cooled for aborts (with water dumped after take-off) and the tail fin has been sized to support steering with one engine out.

I believe Alan Bond has also said Skylon could generate enough thrust to continue flying using the bypass burners alone in the event of an engine failure.

Quote
b.  Jet engines are not working at the edge and they can contain a destructive failure or even fall off.

Skylon's test flight schedule is designed to test the limits of the engines so they can be operated within safe limits. I doubt they'll be operating at the edge without any safety margin. The engines only operate for a few minutes, not continuous hours of operation like Airliners, so that will mitigate some issues.

Quote
c.  An airliner fully fueled and ready to fly can sit on the ramp almost indefinitely.  A vehicle that uses cryogenics and hygols has to be monitored.

Agreed, cryogenic fuels require much more careful handling than AV fuels. There shouldn't be any major issues with Skylon having to wait on the runway while problems are resolved - after all standard rockets have to do this fairly frequently, even ones using cryogenics.

However Skylon is won't be using hygols - the OMS and RCS systems will use LH2/LO2.

The thing is that REL are trying for airport-like operations, but that doesn't mean it'll operate exactly like modern airliners, as there are and will be significant differences.

However it is intended to operate in a way which is much closer to normal airport operations than any other launch vehicle.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/07/2015 02:13 pm

1.  Agreed, cryogenic fuels require much more careful handling than AV fuels. There shouldn't be any major issues with Skylon having to wait on the runway while problems are resolved - after all standard rockets have to do this fairly frequently, even ones using cryogenics.

2.  However Skylon is won't be using hygols - the OMS and RCS systems will use LH2/LO2.

3.However it is intended to operate in a way which is much closer to normal airport operations than any other launch vehicle.


1.  Hence the need for personnel in a launch control center.  I doubt that Skylon will wait on the runway.  It would wait on the fueling ramp/pad while getting topped off.    Or there will be a topping off station at the end of the runway.

2.  Its payloads will.

3.  It will be closer to other launch vehicle operations than airport operations.  Take away to the tow to the runway and the rest is like other vehicles.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/07/2015 02:22 pm

Skylon's test flight schedule is designed to test the limits of the engines so they can be operated within safe limits. I doubt they'll be operating at the edge without any safety margin.

No different than any other rocket engine.   All rocket engines are operated within safe limits with margin.  It still doesn't change the fact that is a large amount of power in a small package and a lot of rotational energy.  That is what is meant by "working on the edge".   As far as rocket engines go, ground tests vs flight tests, there is no difference.  It is just operation time and hence Skylon has no advantage.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/07/2015 04:03 pm

That's useful insight, thank you. I've never dealt with anything scarier than LPG, what are the problems with cryogenic fuel handling that make you think the design has missed?

It uses LH2, which boils off quickly.   They have only talked about the flight vehicle and not the ground support equipment.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hanelyp on 12/07/2015 04:25 pm
LH2 has a known boil off rate for a given tank and ambient conditions.  A factor to be engineered into the design, not a show stopper.  Consider that the tanks and heat shields will need to deal with a period of supersonic flight, with a hot skin.  This implies to me some insulation.  A limited amount of boil off should be part of the design.  For a moderately extended hold I don't expect too much trouble driving out a truck to top off the tanks.  Longer holds (hopefully very rare) imply return to the hanger.

The one factor that comes to my mind where airliner style operations may come short for Skylon needs is on schedule liftoff when heading to a specific orbit.  The spaceplane may need to schedule a launch window.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/07/2015 05:02 pm

I thought a fair amount of consideration had been put into the ground support equipment
Pages 26-28 of the concept manual outlines the Ground Operations Sequence and Timing  (pages34-36 of the PDF)


Not really.  This is the first time I have seen it and it has some holes.  The first thing I saw that is wrong is the payload integration facility.  Totally unrealistic.

And the timeline is just as funny as the two week shuttle turnaround. 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/07/2015 05:04 pm
Regardless of how long of a hold, LH2 is boiling off, especially at the beginning of tanking.  This will necessitate a vent line and a flare stack.  The vehicle is not going to sit on the runway venting H2 to the atmosphere.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/07/2015 05:12 pm
LH2 has a known boil off rate for a given tank and ambient conditions.  A factor to be engineered into the design, not a show stopper.  Consider that the tanks and heat shields will need to deal with a period of supersonic flight, with a hot skin.  This implies to me some insulation.  A limited amount of boil off should be part of the design.  For a moderately extended hold I don't expect too much trouble driving out a truck to top off the tanks.  Longer holds (hopefully very rare) imply return to the hanger.


LH2 doesn't do a "limited" amount of boil off.   It vigorously boils off.   The replenishment that other launch vehicle do is not just to replace the boil off but to keep the bulk temperature down.   It takes more than "some" insulation.  Not just ice but liquid air forms on inadequately insulated tanks.  Regardless of the hold time, Skylon will need insulation equivalent to the shuttle external tank.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 12/07/2015 05:27 pm
The propellants are loaded subcooled.

Also, the tankage is indeed insulated.  It's just that it's inside the spaceframe truss, which is inside the TPS, so you don't see the insulation.

What exactly is unrealistic about the payload integration facility?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 12/07/2015 05:48 pm
How do you "subcool" LH2??
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/07/2015 05:50 pm
The propellants are loaded subcooled.

Also, the tankage is indeed insulated.  It's just that it's inside the spaceframe truss, which is inside the TPS, so you don't see the insulation.

What exactly is unrealistic about the payload integration facility?

No access platforms to the payload bay. 
It is a facility for hazardous operations, hence no offices much less a "passenger terminal" in it.
IOS 9 is not really a clean room. 
side by side vehicles for payload integration?  Means lifting payloads over other vehicles.  Not to mention that with the hilarious timelines, the payload installation is only 30 minutes and there will be need for 3 vehicles at a time?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/07/2015 08:52 pm
Not really.  This is the first time I have seen it and it has some holes.  The first thing I saw that is wrong is the payload integration facility.  Totally unrealistic.
So you're quite a long way behind the curve. Perhaps you should do more background reading first?
Quote
And the timeline is just as funny as the two week shuttle turnaround.
"Payload integration" for aircraft is basically loading the cargo on the plane in a container or strapping it down to deck fittings.

REL staff did work on payload integration for the Shuttle. They are aware of the issues around Coupled Loads Analysis, which is why they don't plan to bolt the payloads to the airframe.

It uses LH2, which boils off quickly.   They have only talked about the flight vehicle and not the ground support equipment.

Indirectly they have.  It's in their references to the use of sub cooled propellants to avoid tank venting. Either the vehicle launches before the system starts to boil or the propellants recycle to long term storage.

How do you "subcool" LH2??
Sub cooling of LH2 was demonstrated as part of the X33 programe. It was one of the few parts that worked quite well.

Historically people have used LHe to cool the LH2 further. Simple in concept but expensive because He is very difficult to cool, keep cool and obtain in propellant tank sized quantities. IIRC the X33 programme use LH2 to cool LH2. 

The heat exchanger coils are in a tank of LH2.  By sucking out the vapor you can lower the BP of the coolant, despite both sides of the cooling loop having the same fluid. The down side is you need some pretty big fans to suck the vapour out fast enough.

The better the HX design the smaller the temperature difference the HX needs to function. IIRC X33 (with hardware from Barber Nicholls, who went on to supply the early SX turbo pumps) got it down to 1-2c. This is important. A small temperature difference across the HX means you don't need to suck out the vapour to such a low pressure, letting you use smaller fans. The fans took (IIRC) about 3x the energy as the system extracted from the LH2. 

And REL are very good good at building heat exchangers.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 12/08/2015 01:00 pm
I mean selling launches /before/ all orbital launches have been completed.

Just 2 years of flight testing for 400 flights is VERY optimistic, as we can see from SpaceShipTwo and other reusable test-bed vehicles.

And yes, I do think that such expensive vehicles will be a hard sell, especially with the significant ground support equipment that will be necessary.

There will be a lot of pressure by investors to get earlier income. That's why I think that if Skylon ever happens, Reaction Engines will be initially operating Skylon for customer launches (during the "test program," if you like). And at that point, it'd be really tempting to just continue operating, since they'll already have the infrastructure in place.

And of course, customers of Skylon would know this. That's part of why I am skeptical of the "just sell Skylons to people, and ignore the actual launch market." If Skylon ever happens, I really doubt that's how it will work.

I actually don't see the point of them doing 200-400 test flights and not at least using a few of them to place actual satellites in orbit.

Especially if the first few orbital flights are completed, especially if they are done without any major problems cropping.

These won't necessarily be big satellites, but things like cube satellites, small research satellites from universities and schools.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/08/2015 02:00 pm

REL staff did work on payload integration for the Shuttle. They are aware of the issues around Coupled Loads Analysis, which is why they don't plan to bolt the payloads to the airframe.


Nonsense.  Don't know where to start since so much is wrong in that statement.
A.  The need for CLA's  is not determined by the method of attachment. 
b.  ELV's use clamp bands and still some have CLA issues
c.  It is more about the spacecraft structural stiffness
d..  A bolted interface was not the driver of shuttle CLA issues
d.  Skylon is using an interface that similar if not identical to the shuttle, the trunnion.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/08/2015 02:01 pm

Indirectly they have.  It's in their references to the use of sub cooled propellants to avoid tank venting. Either the vehicle launches before the system starts to boil or the propellants recycle to long term storage.


Subcooling doesn't prevent boil off
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 12/08/2015 02:14 pm
I mean selling launches /before/ all orbital launches have been completed.

Just 2 years of flight testing for 400 flights is VERY optimistic, as we can see from SpaceShipTwo and other reusable test-bed vehicles.

And yes, I do think that such expensive vehicles will be a hard sell, especially with the significant ground support equipment that will be necessary.

There will be a lot of pressure by investors to get earlier income. That's why I think that if Skylon ever happens, Reaction Engines will be initially operating Skylon for customer launches (during the "test program," if you like). And at that point, it'd be really tempting to just continue operating, since they'll already have the infrastructure in place.

And of course, customers of Skylon would know this. That's part of why I am skeptical of the "just sell Skylons to people, and ignore the actual launch market." If Skylon ever happens, I really doubt that's how it will work.

I actually don't see the point of them doing 200-400 test flights and not at least using a few of them to place actual satellites in orbit.

Especially if the first few orbital flights are completed, especially if they are done without any major problems cropping.

These won't necessarily be big satellites, but things like cube satellites, small research satellites from universities and schools.
If you read the papers I posted you'll see that one off them was a paper outlining a plan to use the 20 test flights of the SUS to launch a series of space exploration missions using generic probes. Another paper outlines the purpose of the test programme, besides putting 204 flights on an airframe, of testing every mission scenario in the user manual which by definition means they will be putting satellites in orbit as part of the programme.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/08/2015 02:17 pm

"Payload integration" for aircraft is basically loading the cargo on the plane in a container or strapping it down to deck fittings.


This isn't an aircraft nor is it carrying bulk cargo.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Ravenger on 12/08/2015 04:10 pm
This isn't an aircraft nor is it carrying bulk cargo.

It's got wings, takes off from a runway, and flies under its own power, which seems very much like an aircraft to me.

How do you define bulk cargo? The cargo bay is designed to take virtually anything up to the mass limit. That could include bulk items such as water, fuel and other consumables. It'd need specially designed cargo modules, but it'd be possible.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/08/2015 04:29 pm

1.  It's got wings, takes off from a runway, and flies under its own power, which seems very much like an aircraft to me.

2.  How do you define bulk cargo? The cargo bay is designed to take virtually anything up to the mass limit. That could include bulk items such as water, fuel and other consumables. It'd need specially designed cargo modules, but it'd be possible.

1.  It goes into orbit, that negates the aircraft designation.  It is a launch vehicle.

2.  It isn't going to bulk cargo in the beginning.  It is going to deliver spacecraft
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hanelyp on 12/08/2015 05:29 pm
Presuming everything works to plan:
Vehicle comes in.
If in flight diagnostics, schedule, or a quick automated systems check say it needs maintenance, it goes to the maintenance bay.  Another vehicle from the fleet steps in to the rotation.
Otherwise, flush the lines, fill the tanks, charge the batteries, drop in a cargo palate, and head out for the next flight.

Rapid turn around keeping the vehicle flying is the essence of "aircraft like" operations we want to capture.  Runways and wings are artifacts that may or may not play a role when we finally get a working system.

Liftoff time may be more constrained by destination orbit, and maintenance likely more frequent than a mature tech airliner, but without cutting the time and effort needed to refit between flights cost won't go where we need it.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 12/08/2015 06:02 pm

1.  It's got wings, takes off from a runway, and flies under its own power, which seems very much like an aircraft to me.

2.  How do you define bulk cargo? The cargo bay is designed to take virtually anything up to the mass limit. That could include bulk items such as water, fuel and other consumables. It'd need specially designed cargo modules, but it'd be possible.

1.  It goes into orbit, that negates the aircraft designation.  It is a launch vehicle.

2.  It isn't going to bulk cargo in the beginning.  It is going to deliver spacecraft

So is it still not an aircraft when it's not going into orbit?
Is it not an aircraft when it's just flying from the factory to Kourou?
Or is it an aircraft then but it suddenly ceases to be one when the nose points up?
What if it aborts orbital launch at Mach 5 and turns round around and flies back to the runway, did the intention to perform orbital launch make it not an aircraft and the abort turn it into one?
Or would it have been an aircraft until the launch is completed and the abort just stopped it turning into not an aircraft?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Chris Bergin on 12/08/2015 09:43 pm
Too many low quality posts. You're wasting your time because they will be deleted and you will be barred from posting on this thread again.

Trimmed. No more, and I mean no more crap like "It won't work. It's not what I like." etc. It's boring and embarrassing for a site like this.

And will someone for the love of God go round to Jim's house and show him have to respond to someone without making 15 posts. ;)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/08/2015 10:11 pm
Subcooling doesn't prevent boil off
But it will delay tank pressure rising to the point it becomes necessary, by which time either the Skylon will be on it's way to orbit and burning through the tank contents at a fair rate or it will have been recycled back to the hangar.

People think sub cooling is a nice to have bolt on but it's much better planned in from the start. With Skylon it is.

1.  It goes into orbit, that negates the aircraft designation.  It is a launch vehicle.
Skylon operates under the UK CAA rules.

It gets it's lift from wings while in UK airspace. That makes it an aircraft.

Nonsense.  Don't know where to start since so much is wrong in that statement.
At the beginning, then move to the middle and proceed to the end?  :)
Quote
A.  The need for CLA's  is not determined by the method of attachment. 
True. It's set by the wafer thin structural margins of most ELV's and the practice hard mounting to the LV, making for superb coupling between 2 major structures with opportunities to excite all kinds of failure modes.

Seriously LV's are the only transport systems that often require the cargo to be redesigned multiple times because it could be shaken to bits, or cause it's carrier can be shaken to bits by the resonance it can excite back into the carrier vehicle.

The reaction of the industry to this seems to have been "Oh well, that's just what you have to do to build a payload."

An attitude which in any other situation would have had the customers saying "No we don't. Get it fixed or we go elsewhere."
Quote
b.  ELV's use clamp bands and still some have CLA issues
I used CLA issues as an indication that REL are aware of all of the issue around payload integration between payloads and LV's.
Quote
c.  It is more about the spacecraft structural stiffness
I'd suggest the size and position of any spacecraft fluid tanks might be some effect on things as well. The point is it should have no effect. It should not require an FEA simulation to determine if there is or is not a problem.
Quote
d..  A bolted interface was not the driver of shuttle CLA issues
True. But I would ask if CLA was as big a problem with Shuttle as it is with ELV's?
Quote
d.  Skylon is using an interface that similar if not identical to the shuttle, the trunnion.
Which may or may not be a problem. OTOH the engines are not sitting directly behind the payload (as they were on Shuttle) to excite direct longitudinal vibrations.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/08/2015 11:15 pm

1.  It gets it's lift from wings while in UK airspace. That makes it an aircraft.

2.  true. It's set by the wafer thin structural margins of most ELV's and the practice hard mounting to the LV, making for superb coupling between 2 major structures with opportunities to excite all kinds of failure modes.

3.  Seriously LV's are the only transport systems that often require the cargo to be redesigned multiple times because it could be shaken to bits, or cause it's carrier can be shaken to bits by the resonance it can excite back into the carrier vehicle.

4.  I'd suggest the size and position of any spacecraft fluid tanks might be some effect on things as well. The point is it should have no effect. It should not require an FEA simulation to determine if there is or is not a problem.

5.  True. But I would ask if CLA was as big a problem with Shuttle as it is with ELV's?


1.  Not talking about regulations but the approach from an operations and structural POV
2.  No, it about controllability of vehicle and not structural margins
3.  Seriously, its not.  More nonsense and exaggeration
4.  FEA is a basic aerospace tool.  It is not unique to spacecraft and launch vehicles.  Aircraft do it too.  But as far as CLA, Skylon isn't going to be any different from the shuttle, so they will be done.
5.  Neither were/are a big problem
6.  Engine location is not going to matter. Skylon has mass on both sides of the wing, it is going to have its own unique issues.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 12/08/2015 11:38 pm
Seriously LV's are the only transport systems that often require the cargo to be redesigned multiple times because it could be shaken to bits, or cause it's carrier can be shaken to bits by the resonance it can excite back into the carrier vehicle.

Umm... yes.
LVs are also the only transport systems I am aware of that expose their cargo to multiple g's of acceleration during most of the transport time and Skylon will be no exception to this, won't it?

Also, all other transport systems I'm aware of tend to require you to surround your sensitive cargo with extensive packaging which is usually there to mitigate the effects of even much more benign transport conditions and from which the cargo is then carefully being unwrapped after shipment.
Another aspectc Skylon doesn't really have in common with "other" transport systems.

So it occurs to me that Skylon will still look much more in common with traditional LVs than with traditional air transport if it comes to cargo interfaces.

Yes, shipping water, fuel and raw materials for whatever reason might result in simplified cargo interfaces but I suspect most of the cargo will still, like Jim said, be spacecraft.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 12/09/2015 12:31 am

there is a difference in theory, and there is a difference for Skylon according with REL own plans. You might not like them, you might believe they are unrealistic and that "reality" today is different, but then again if anything that differs from how things are done today is unrealistic for the simple fact that they are not done today, why do you even bother about Skylon?

You are right.  I shouldn't bother since there is too much nonsense, unsupported conjecture and flat out just wrong statements on this thread.  Much of it should be in the scifi section because it isn't reality or come close to it.

Good, I'm glad we agree to disagree. Now it would be very kind of you if you could let us continuing our "nonsense conjectures" without further poisoning the discussion..

To me, having someone who disagrees isn't poisoning the discussion.

Poisoning the discussion is asking someone you disagree with to go away.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 12/09/2015 02:06 am
To me, having someone who disagrees isn't poisoning the discussion.
It depends on how they disagree. A great deal of insight can be gained from disagreements, provided they're presented in a more constructive form than "that's nonsense"

I agree, and sometimes Jim's posts are just that.  But I saw quite a few posts here where he posted more than just "that's nonsense".
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/09/2015 02:38 am
Umm... yes.
LVs are also the only transport systems I am aware of that expose their cargo to multiple g's of acceleration during most of the transport time and Skylon will be no exception to this, won't it?
Interesting choice of phrase since it neatly excludes all carrier landings and take offs. AFAIk the Grumman C2 Greyhound subjects it's payload (about 4 tonnes of passengers and cargo) to about 2.25g  for about 3 secs without any special design.
Quote
Also, all other transport systems I'm aware of tend to require you to surround your sensitive cargo with extensive packaging which is usually there to mitigate the effects of even much more benign transport conditions and from which the cargo is then carefully being unwrapped after shipment.
Except accleration is one of those things you can't shield the insides of the payload from, so packaging has limited use. OTOH cutting down the vibration and noise inside the payload bay can pay big dividends in payload survival.
Quote
So it occurs to me that Skylon will still look much more in common with traditional LVs than with traditional air transport if it comes to cargo interfaces.
As always with these questions it's a matter of how much Skylon resembles an ELV and how much it resembles an aircraft.

The simple answer is it resembles  an aircraft a lot more than Shuttle did and it's very unlike an ELV.

The shuttle mounting was very configurable - trunion mounts and keel points could be bolted between (almost?) any pair of ribs. The Skylon concept has a forward mounting position and a rear mounting position, in both cases the three trunion mount design will have a very clearly defined specification of what you can put in it.
I think that was more a problem than a strength. The mounting hardware in the different locations was unique, multiplying the number of simulation runs needed to see if a certain set of payloads would be OK, or if they would interact badly.
Quote from: https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36826.0;attach=1083478
One area of the SKYLON airframe that was refined as part of the S-ELSO Study was the payload interfaces.  There were two reasons for reconsidering at the interface design.  The first reason was that pre- study work by 42 Technology Limited suggested the previous design as defined in Issue 1 of the SKYLON Users’ Manual could be optimised to both reduce mass and reduce the load coupling.  This design goal of the interface only carrying the payload inertial loads was considered important as it was hoped that the need for coupled structure analysis of payload and launcher could be eliminated
They are a problem if one is trying to adopt a airline-like operational model.
True. IIRC Hemsell mentioned that CLA was a large (but hidden) cost of all LV operations, which just does not exist for other modes of transport.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/09/2015 03:59 am
I think that was more a problem than a strength. The mounting hardware in the different locations was unique, multiplying the number of simulation runs needed to see if a certain set of payloads would be OK, or if they would interact badly.


No, the CLA only was twice per mission, which was standard.  Multiple runs are not required. It is not a big deal as you say.

Also, Skylon having fixed attach points doesn't make CLA go away.  ELVs have fixed attach points.  Again, it is the structural stiffness of the payload and how it will interact with the carrier.

And yes, aircraft manufacturers have to do special analysis when carrying large unique cargo. 
like these:

http://i0.wp.com/www.defensemedianetwork.com/wp-content/uploads/2012/06/AN124-Condor-Heavy-Lift.jpg
http://www.chapman-freeborn.com/blog/wp-content/uploads/2013/12/AN-124-TRN-REC-Photo-3-December-2013.png


Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 12/09/2015 04:10 am
Interesting choice of phrase since it neatly excludes all carrier landings and take offs. AFAIk the Grumman C2 Greyhound subjects it's payload (about 4 tonnes of passengers and cargo) to about 2.25g  for about 3 secs without any special design.
So you are saying you can carry any cargo in such a setup without special handling?
Plus, that's a high g-force for what? 3s?

Quote
Except accleration is one of those things you can't shield the insides of the payload from, so packaging has limited use.
Huh? Ever bought a washing machine?
Adding support packaging for fragile structures _within_ a device is an absolute standard procedure for anything somewhat susceptible to load issues.
A lot of things are also being shipped partly disassembled for the same reason.

It's an absolute standard procedure to have extensive processing for cargo to ship it through no so benign conditions yet it's something you can't easily do for most spacecraft.
Where you can (think shipping to ISS) it's of course done.

Quote
As always with these questions it's a matter of how much Skylon resembles an ELV and how much it resembles an aircraft.
Sure. So have you seen how spacecraft are shipped in an aircraft. Does that anyhow resemble how it would be shipped with Skylon?
This is how aircraft shipping of a spacecraft looks like:
http://www.satnews.com/images_upload/1323524237/Aspace_VA209_Arrival.jpg

Quote
The simple answer is it resembles  an aircraft a lot more than Shuttle did and it's very unlike an ELV.
OK, so it will be launched unfueled, partly assembled, in a container and with extensive packaging? And then it will be processed in orbit? Interesting, didn't know that.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 12/09/2015 11:15 am
Umm, you are aware my comments were not about ground handling but launch?
So you think spacecraft will be launched by Skylon packaged in a shipping container? Who's going to unpack them on orbit?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 12/09/2015 06:28 pm
No your comments were a bizarre strawman argument involving supporting the drum in a washing machine, that somehow didn't need supporting when being thrown around on top of a rocket.
Quite to the contrary.
My comment was giving a real-world, low-tech example to counter a bizarre claim that packaging would never support the internals of the shipped goods.

The point is that in "normal" shipping operations you _do_ package stuff up with all kind of special transport packaging and support to make sure it arrives in one piece.
That's the exact process that allows you to standardize on the shipping interfaces. You don't need any special support and CLA between your vehicle and the transport container because all of the sensitive load handling is being done through packaging which is being removed after shipment.

In cases where you can't do this you will find less standardized interfaces.

For a spacecraft you can't do that. You have high loads, vibrations and very little packaging because nobody can have an extended unpacking and reassembly process after delivery to orbit.

That is the reason why spacecraft have to be designed for the load environment they are seeing during launch and that factor is not going to be significantly different for Skylon than for traditional LVs.
Quite to the contrary: due to the horizontal takeoff you have even more complicated load situations because you have acceleration in several axis.


Quote
A shipping container is the standardised form factor for flying things in a plane. The three trunion mount is the standardised form factor for flying things in Skylon. The SPLC concept is intented to allow existing bus designs to be flown with little modification, by acting as an adaptor.
The shipping container (together with packaging and partial disassembly for shipping) is a way to move the problem of handling loads (coupled or not) away from the vehicle interface.
Unless you find a way to do the same for the spacecraft being launched with Skylon your operations will not resemble a standard shipping container.
And I don't see anything specific to the Skylon that would make this any easier than for any other LV.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/09/2015 09:17 pm
It appears to have a dust cover. It appears to be mounted to the container by the same interface the launch vehicle will use. No signs of extensive packaging to me.


The launch vehicle interface is on the side during terrestrial shipping.  There are additional restraints on it that would have to be removed.   And there are additional covers on specific instruments. 

The spacecraft shown is one of the smaller GEOsats and not typical.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/09/2015 09:26 pm

The LEO facility that straps them to a Fluyt to get them where they're going


Adding more operations adds more risk and costs.   Also, and how many LEO facilities are there going to be to service spacecraft to different orbits.   Also, there isn't going to be a LEO facility for quite some time if at all for that kind of support.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 12/10/2015 01:02 am
The claim made was that packaging wouldn't be used to support  the internals of a payload (the context being of a launch vehicle payload that wouldn't be processed on orbit)
The claim was made that transport in Skylon is the same as other means of transport and that this would somehow be fundamentally different from how LVs work today. And that it would no longer be needed to redesign payloads for the LV environment because that's also not what you do with other means of transport.
Which doesn't hold because other means of transport usually expect the cargo to be in a condition that matches the transport environment and if that's not the case you solve it through packaging.

Since that's not an option here the payload WILL have to be able to withstand the launch conditions and that will indeed require a good deal of understanding of - among other things - coupled loads.

It happened with Shuttle around which a whole generation of payloads was designed. But Skylon won't have a law behind it mandating exclusivity so a spacecraft will have to match different vehicles. Few operators will rely on only one launch option, at least in the beginning.

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But absolutely, the payload has to be designed to handle the load environment. For a washing machine being moved when not in use this involves removable spacers.

And that's what was debated and that I was answering to:

Seriously LV's are the only transport systems that often require the cargo to be redesigned multiple times because it could be shaken to bits, or cause it's carrier can be shaken to bits by the resonance it can excite back into the carrier vehicle.
I replied that this is exactly the case because in other transport systems you solve this problem through disassembly or packaging.
Where you can't do this, e.g. weapons on mil. aircraft the designer is usually well aware of the environment.





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I don't expect it to visually look like a shipping container, I expect it to look like three trunions - but I expect the operations around it to resemble the operations around a shipping container, i.e. a well understood form factor with reasonable tolerences and defined load environment that is easy to handle in a routine and automated way.
But that's not really different to other LV operations, isn't it? I mean, part of the whole EELV activity was to define a standardized payload environment.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/10/2015 01:43 am

the launch vehicle interface appears to be on the front-right side in the second picture - and it appears to me that that is where the spacecraft is being secured to the base. As the picture shows the cover being lowered I'm not sure there are any further restraints - there might be some on what would be the top when it is vertical, but I'd be surprised if that was designed to be load bearing.


There are further restraints and not just on LV interface.  One on end opposite of the LV interface and at the base of the container.

Been around many spacecraft and containers.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/10/2015 08:13 am
There are further restraints and not just on LV interface.  One on end opposite of the LV interface and at the base of the container.

Been around many spacecraft and containers.
Going back to an earlier post of yours.

I'm curious. Do people load payload propellant on the pad anymore?

I know OMS/RCS loading for Shuttle was mandated that way but AIUI the propellant systems for payloads are designed to eliminate any leak path from the tanks or vapors getting into the system to corrode it before launch with an actual barrier in the flow path that needs to be punctured by a pyrovalve to allow flow to start. [EDIT Likewise AIUI once the system is filled it's fill points are also sealed ]
 
Since Skylon has no hypergols in it's design I'd wonder just how "hazardous" would such an area be, although if people are using solids there's always a risk of unexpected ignition.

[EDIT I'm not sure how the SX Dragon system will work, give it has hypergols designed in and yet is designed for reuse. Sealing the fill caps always sound a pretty one-shot deal to me.  ]
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/10/2015 01:50 pm

1.  I'm curious. Do people load payload propellant on the pad anymore?

2.  I know OMS/RCS loading for Shuttle was mandated that way but AIUI the propellant systems for payloads are designed to eliminate any leak path from the tanks or vapors getting into the system to corrode it before launch with an actual barrier in the flow path that needs to be punctured by a pyrovalve to allow flow to start. [EDIT Likewise AIUI once the system is filled it's fill points are also sealed ]
 
3. Since Skylon has no hypergols in it's design I'd wonder just how "hazardous" would such an area be, although if people are using solids there's always a risk of unexpected ignition.


1.  There are still a few and the upper stages load ACS propellant at the pad.

2.  It is not a puncture and not all are pyro.

3.  There are still leak paths and precautions are taken around fueled spacecraft no matter where they are.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/10/2015 07:26 pm
1.  There are still a few and the upper stages load ACS propellant at the pad.

2.  It is not a puncture and not all are pyro.

3.  There are still leak paths and precautions are taken around fueled spacecraft no matter where they are.
Interesting. I'll note Skylon COP is built built around using the Skylon Upper Stage for BEO missions. It would probably have propellant loading done at the fueling apron along with the main tanks. IIRC it's ACS is designed to go with GH2/GO2 propellants. The problem would then be if a customer insisted on using a storable upper stage which was not delivered to the payload loading area fueled. I'd be very surprised at anyone wanting to do this.

Personally I'm glad some builders are moving away from pyro systems if possible. I understand they're reliability record is excellent but the shock signatures hammer everything in their immediate vicinity and depending on range rules you could end up installing them on the pad, which looks like a PITA. I still find it hard to believe Shuttle had 300 of them.  :(

However it's done it was my understanding that SOP for hypergolic systems is that there is a physical barrier between the tanks and the rest of the system, and possibly another one just upstream of the thrust chambers to prevent any sort of atmospheric attack during long term storage.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/11/2015 12:08 am
1.  Interesting. I'll note Skylon COP is built built around using the Skylon Upper Stage for BEO missions. It would probably have propellant loading done at the fueling apron along with the main tanks. IIRC it's ACS is designed to go with GH2/GO2 propellants. The problem would then be if a customer insisted on using a storable upper stage which was not delivered to the payload loading area fueled. I'd be very surprised at anyone wanting to do this.

2. Personally I'm glad some builders are moving away from pyro systems if possible. I understand they're reliability record is excellent but the shock signatures hammer everything in their immediate vicinity and depending on range rules you could end up installing them on the pad, which looks like a PITA. I still find it hard to believe Shuttle had 300 of them.  :(

3.  However it's done it was my understanding that SOP for hypergolic systems is that there is a physical barrier between the tanks and the rest of the system, and possibly another one just upstream of the thrust chambers to prevent any sort of atmospheric attack during long term storage.

1.  It's the spacecraft with all the hyperbolas

2. Spacecraft still use a lot of them and the range doesn't require them to installed at the pad.  Don't know where you got that info.

3.  Yes,they are called valves.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Prober on 12/12/2015 04:27 pm
It seems to me that there could be a chance for REL to develop something which would not be economically worthwhile  if done by themselves but might be militarily worthwhile to the USAF.

How could one turn up one's nose at a chance to try out some aspects of Skylon/Sabre without needing to go directly to a $10 billion SSTO?  It could be a godsend.

That might control what aspects the engine demonstrator has to be most realistic about, how much money has to be spent on it and where.

That's my view why turn down money to develop technology that may eventually help you achieve your commercial aims.

My only fear is the USAF 'locking up' some vital technology for their use only.

think contrarian....who says the USAF doesn't have this technology ? Maybe the USAF needs a way to bring the tech out to the public without compromising the program.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/12/2015 05:36 pm
1.  It's the spacecraft with all the hyperbolas
That doesn't make sense. Can you explain it further?
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2. Spacecraft still use a lot of them and the range doesn't require them to installed at the pad.  Don't know where you got that info.
Mostly thinking of the Shuttle launch procedure. I just remembered Ariane does not mandate this and I guess outside of NASA it's not that common.
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3.  Yes,they are called valves.
I was unclear. I meant a solid fixed metal barrier in the fuel system.  Then again I may just be thinking of the system on the Lance missile, which needed storage times in years.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/12/2015 05:47 pm
think contrarian....who says the USAF doesn't have this technology ? Maybe the USAF needs a way to bring the tech out to the public without compromising the program.

What a very special view of the world you do have.

This is not physics, it's engineering.  Anyone could have most of this technology if they were willing to spend the time and money (and by USAF the money was tiny) to develop it.

But nobody has and the USAF and spent billions on the X30 programme instead, which was 3x bigger han REL's entire projected next phase budget and delivered nothing in return IE yet another SCRamjet engine attempt.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Prober on 12/12/2015 07:24 pm
think contrarian....who says the USAF doesn't have this technology ? Maybe the USAF needs a way to bring the tech out to the public without compromising the program.

What a very special view of the world you do have.

This is not physics, it's engineering.  Anyone could have most of this technology if they were willing to spend the time and money (and by USAF the money was tiny) to develop it.

But nobody has and the USAF and spent billions on the X30 programme instead, which was 3x bigger han REL's entire projected next phase budget and delivered nothing in return IE yet another SCRamjet engine attempt.

as someone said earlier in the thread this is 1960's stuff, I agree.

take the "PDE"; some years ago I walked outside my home looked in the sky because I saw an unusual con trail.  It was unusual because it looked like donuts dropping from the sky then dissipating.  Yes, its about engineering hence my beliefs.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/13/2015 04:24 pm
1.  It's the spacecraft with all the hyperbolas
That doesn't make sense. Can you explain it further?

2.  Mostly thinking of the Shuttle launch procedure. I just remembered Ariane does not mandate this and I guess outside of NASA it's not that common.


1.Hypergols.  Autocorrect error

2.  Wasn't applicable to the shuttle either.  There even was pyros in the Spacehab module and they were installed for months.   You are getting pyros mixed up with safe and arm devices which are used on solid motors.  But still it wasn't the installation, it was the activation that had to be done at the pad
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hanelyp on 12/13/2015 08:56 pm
One point of the Skylon concept, as I understand it, is avoidance of hypergols and other similarly difficult fluids.  Not that liquid hydrogen is easy, but it isn't prone to the same chemical reactions in storage or if small quantities leak around the plumbing.

Whether installation or activation, individual manual work on pyrotechnics is bad for quick and affordable launch.  On that point an electro-mechanical release that doesn't need personal attention for each launch has a great advantage.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/13/2015 09:11 pm
1.  One point of the Skylon concept, as I understand it, is avoidance of hypergols and other similarly difficult fluids. 
2.  Whether installation or activation, individual manual work on pyrotechnics is bad for quick and affordable launch.  On that point an electro-mechanical release that doesn't need personal attention for each launch has a great advantage.

1.  Payloads can't avoid them

2.  Mechanical does have the same reliability.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Soundbite on 12/15/2015 04:25 pm
I don't know if anyone is interested, but there is an article today on MailOnline http://www.dailymail.co.uk/sciencetech/article-3359967/Spaceplanes-vs-super-rockets-Expert-reveals-win-battle-cheap-space.html (http://www.dailymail.co.uk/sciencetech/article-3359967/Spaceplanes-vs-super-rockets-Expert-reveals-win-battle-cheap-space.html) where a Bristol University academic compares the estimated cost of a Skylon launch with that of reusable versions of Falcon 9 and Falcon Heavy.  He suggests that Skylon could never compete.  What do you all think?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 12/15/2015 05:29 pm
I don't know if anyone is interested, but there is an article today on MailOnline http://www.dailymail.co.uk/sciencetech/article-3359967/Spaceplanes-vs-super-rockets-Expert-reveals-win-battle-cheap-space.html (http://www.dailymail.co.uk/sciencetech/article-3359967/Spaceplanes-vs-super-rockets-Expert-reveals-win-battle-cheap-space.html) where a Bristol University academic compares the estimated cost of a Skylon launch with that of reusable versions of Falcon 9 and Falcon Heavy.  He suggests that Skylon could never compete.  What do you all think?

Looks like the real difference is the cost of liquid hydrogen compared to kerosine, it is massive, lets hope it's not Skylons "Achilles heel".
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hanelyp on 12/15/2015 06:25 pm
If we can get to the point where the relative cost of LH2 vs. kerosene is a large portion of launch costs, mission accomplished.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/15/2015 11:26 pm
I don't know if anyone is interested, but there is an article today on MailOnline http://www.dailymail.co.uk/sciencetech/article-3359967/Spaceplanes-vs-super-rockets-Expert-reveals-win-battle-cheap-space.html (http://www.dailymail.co.uk/sciencetech/article-3359967/Spaceplanes-vs-super-rockets-Expert-reveals-win-battle-cheap-space.html) where a Bristol University academic compares the estimated cost of a Skylon launch with that of reusable versions of Falcon 9 and Falcon Heavy.  He suggests that Skylon could never compete.  What do you all think?
Historically propellant costs have been in the noise limit of costing estimates for all LV's
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 12/15/2015 11:41 pm
I don't know if anyone is interested, but there is an article today on MailOnline http://www.dailymail.co.uk/sciencetech/article-3359967/Spaceplanes-vs-super-rockets-Expert-reveals-win-battle-cheap-space.html (http://www.dailymail.co.uk/sciencetech/article-3359967/Spaceplanes-vs-super-rockets-Expert-reveals-win-battle-cheap-space.html) where a Bristol University academic compares the estimated cost of a Skylon launch with that of reusable versions of Falcon 9 and Falcon Heavy.  He suggests that Skylon could never compete.  What do you all think?
Historically propellant costs have been in the noise limit of costing estimates for all LV's
In this case, it's really about the development costs, not about the hydrogen costs (although the hydrogen costs do impact development and operations cost, just not for the cost of fuel itself).

In the very long term, with arbitrarily high reuse, then fuel cost matters. But we're not anywhere there, yet.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Asteroza on 12/16/2015 03:46 am
Uh, how far would it hobble Skylon operators to ban traditional toxic hypergols in payloads? Considering all the moves to electric thrusters as it is, what specific scenarios end up essentially needing hypergolic propellants? The missions that come to mind is any kind of short, high thrust scenario where a solid kick stage is undesirable, so some manned systems perhaps?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: tl6973 on 12/16/2015 09:12 am
Uh, how far would it hobble Skylon operators to ban traditional toxic hypergols in payloads?

As much as it would hobble other operators, I would guess.

None of the skylon architecture uses hypergols (the Skylon Upper Stage has SOMA engines which are LoX/ LH2), so it would be the payload builders that would have to go back to the drawing board.




Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 12/16/2015 10:09 am
I don't know if anyone is interested, but there is an article today on MailOnline http://www.dailymail.co.uk/sciencetech/article-3359967/Spaceplanes-vs-super-rockets-Expert-reveals-win-battle-cheap-space.html (http://www.dailymail.co.uk/sciencetech/article-3359967/Spaceplanes-vs-super-rockets-Expert-reveals-win-battle-cheap-space.html) where a Bristol University academic compares the estimated cost of a Skylon launch with that of reusable versions of Falcon 9 and Falcon Heavy.  He suggests that Skylon could never compete.  What do you all think?
Historically propellant costs have been in the noise limit of costing estimates for all LV's
In this case, it's really about the development costs, not about the hydrogen costs (although the hydrogen costs do impact development and operations cost, just not for the cost of fuel itself).

In the very long term, with arbitrarily high reuse, then fuel cost matters. But we're not anywhere there, yet.

It's about development costs, without computing SpaceX development costs.

sure, guess who wins? :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Soundbite on 12/16/2015 10:45 am
Aviation Week has just announced that Reaction Engines are one of their 4 finalists for their Laureate Awards in their Technology section for 2016 See link on Rocketeers http://rocketeers.co.uk/node/4452 (http://rocketeers.co.uk/node/4452).  They are definitely beginning to be noticed State side.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/16/2015 11:36 am
Uh, how far would it hobble Skylon operators to ban traditional toxic hypergols in payloads? Considering all the moves to electric thrusters as it is, what specific scenarios end up essentially needing hypergolic propellants? The missions that come to mind is any kind of short, high thrust scenario where a solid kick stage is undesirable, so some manned systems perhaps?

There isn't "all the moves", it has only been GEO comsats that have done it.  The issue is for attitude control and not orbit changing.  Most spacecraft need thrusters with more power than electric ones.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 12/16/2015 11:39 am


It's about development costs, without computing SpaceX development costs.

sure, guess who wins? :)

Well, this is where all the nonsense about the supposed advantages of separating operator and manufacturer business cases starts to hit you back...

This is not including development costs but costs of one LV.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 12/16/2015 12:15 pm


It's about development costs, without computing SpaceX development costs.

sure, guess who wins? :)

Well, this is where all the nonsense about the supposed advantages of separating operator and manufacturer business cases starts to hit you back...

This is not including development costs but costs of one LV.

Fair enough, but the study compares one LV with 200 flights capability with one with 10, without computing the capital cost you have to recur each10 times for Falcon. Moreover, there is no Fully reusable Falcon yet announced....
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 12/16/2015 12:48 pm
If the cost of the Falcon is total cost then you don't need to calculate any additional capital cost. And anything else would be apples to oranges because the cost of Skylon IS total cost.
Both need to add operations which he argues is more expensive for Skylon which is probably correct.

So it all boils down to interest rates and flight rates...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: tl6973 on 12/16/2015 02:24 pm
I know this is probably impossible to find, but does anyone know what the ground operations costs of something like
the SR71 or the B2 Spirit stealth bomber are like?

Might those be reasonable analogues to the operating costs for Skylon?

I'm sure there are many reasons why not, just want to have a think about required number of personnel, handling facility sizes etc.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 12/16/2015 03:05 pm
If the cost of the Falcon is total cost then you don't need to calculate any additional capital cost. And anything else would be apples to oranges because the cost of Skylon IS total cost.
Both need to add operations which he argues is more expensive for Skylon which is probably correct.

So it all boils down to interest rates and flight rates...

They compute only a one-off count, not a recylce of the acquisition each 10 launches. Basically, it is like buying one skylon and using it 200 times, or buying a falcon 9 and using it 200 times. which is wrong.

Also, keep in mind that a Skylon should have an oeprational life of minimum 30 years. Which means around 6 flights per year, to have the minimu price of  millions. at higher prices you need much less flights.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 12/16/2015 03:28 pm

If the cost of the Falcon is total cost then you don't need to calculate any additional capital cost. And anything else would be apples to oranges because the cost of Skylon IS total cost.
Both need to add operations which he argues is more expensive for Skylon which is probably correct.

So it all boils down to interest rates and flight rates...

They compute only a one-off count, not a recylce of the acquisition each 10 launches. Basically, it is like buying one skylon and using it 200 times, or buying a falcon 9 and using it 200 times. which is wrong.

Also, keep in mind that a Skylon should have an oeprational life of minimum 30 years. Which means around 6 flights per year, to have the minimu price of  millions. at higher prices you need much less flights.

No, that's not true. They use a different scale for the amortization. It's confusing but correct, they assume to buy 20 Falcons for 200 flights.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 12/16/2015 03:48 pm

If the cost of the Falcon is total cost then you don't need to calculate any additional capital cost. And anything else would be apples to oranges because the cost of Skylon IS total cost.
Both need to add operations which he argues is more expensive for Skylon which is probably correct.

So it all boils down to interest rates and flight rates...

They compute only a one-off count, not a recylce of the acquisition each 10 launches. Basically, it is like buying one skylon and using it 200 times, or buying a falcon 9 and using it 200 times. which is wrong.

Also, keep in mind that a Skylon should have an oeprational life of minimum 30 years. Which means around 6 flights per year, to have the minimu price of  millions. at higher prices you need much less flights.

No, that's not true. They use a different scale for the amortization. It's confusing but correct, they assume to buy 20 Falcons for 200 flights.

do you have a link to the original document? the newspaper article is totally confusing on so many factors that makes little sense to keep commenting on it, but if you have the full document I'd be pleased to read it
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/16/2015 10:26 pm
Uh, how far would it hobble Skylon operators to ban traditional toxic hypergols in payloads? Considering all the moves to electric thrusters as it is, what specific scenarios end up essentially needing hypergolic propellants? The missions that come to mind is any kind of short, high thrust scenario where a solid kick stage is undesirable, so some manned systems perhaps?
There's been a lot of talk about electric only propulsion for comm sats but like all parts of the space industry their designers are very conservative and toxic hypergols will not be phased out by anyone over night.

The thing is electric is not a clear win. You (in theory) trade longer station keeping with increased damage from extended passes through the inner Van Allen radiation belt,  unless you fly a Skylon/SUS trajectory to around 5900Km, skipping that part.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/16/2015 11:16 pm
Well, this is where all the nonsense about the supposed advantages of separating operator and manufacturer business cases starts to hit you back...

This is not including development costs but costs of one LV.
That "nonsense" that every transport system mfg and operator follows which does not operate a transport system based around a design for a strategic weapon system uses?

Of course if they did space launch using say, some refurbished artillery pieces they probably would follow the combined mfg/operator model as well.

Funny how that's not taken off as a concept, isn't it
Title: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 12/16/2015 11:23 pm
Well, this is where all the nonsense about the supposed advantages of separating operator and manufacturer business cases starts to hit you back...

This is not including development costs but costs of one LV.
That "nonsense" that every transport system mfg and operator follows which does not operate a transport system based around a design for a strategic weapon system uses?

Of course if they did space launch using say, some refurbished artillery pieces they probably would follow the combined mfg/operator model as well.

Funny how that's not taken off as a concept, isn't it

The nonsense is not to structure the business that way. This can actually make a lot of sense.

But it's nonsense to claim that it would reduce costs. It doesn't. It can help handle risk (not necessarily lower it but make it easier to handle or limit) and it helps to have more appropriate business models for development, manufacturing and operations but it doesn't by itself reduce any costs. That claim was made and it's nonsense.

And now somebody else turns that thing on its head and makes the similarly nonsensical claim that this structure would INCREASE the cost (it doesn't, it may make it more obvious or visible but it doesn't in itself cause fundamental additional costs), that's what I wanted to point out.

It's kind of fair :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/16/2015 11:29 pm

That "nonsense" that every transport system mfg and operator follows which does not operate a transport system based around a design for a strategic weapon system uses?

Of course if they did space launch using say, some refurbished artillery pieces they probably would follow the combined mfg/operator model as well.

Funny how that's not taken off as a concept, isn't it

The nonsense is the comparison to ICBMs and strategic weapon systems,

Space Launch is different than other transport systems because of the energies involved and it is a transitional system.  All other modes of transport have a steady state mode of operation, where most parameters are static.  Also, when power is removed, all other modes have graceful degradation.
Title: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 12/16/2015 11:29 pm
Btw, I don't get the point why everybody here seems to assume that building and operating a space launch vehicle in the same entity would be something totally common just because that's how SpaceX and some other NewSpace companies are trying to do it. I mean... That's quite a new model, not even ULA has operated that way until now.

And strategic weapon systems are definitely not being operated by their manufacturers
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 12/17/2015 06:47 am
Hypersonic strategic air-lift anyone?

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Potentially beneficial developments include faster computer processing, lighter logistics chains, 3D printing and “perhaps even hypersonic strategic air-lift”, plus autonomous weapon systems such as unmanned combat air vehicles.

https://www.flightglobal.com/news/articles/uk-predicts-more-stealthy-and-stand-off-ops-by-2035-420125/
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/17/2015 09:02 am
The nonsense is the comparison to ICBMs and strategic weapon systems,
Not really. All current LV's are multi stage one shot designs, exactly like ICBM's. the biggest difference is they trade the performance of liquid fuels with poor long term storage (in flight weight tanks) over the long term storability of solids. I think ICBM's also tend to operate to higher g limits but I have no doubts you could back convert any current generation ELV to an ICBM quite easily. I'm not saying anyone would want to, simply that with a suitable (nuclear) payload it would not be that difficult and everyone interested in this subject knows that.
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Space Launch is different than other transport systems because of the energies involved and it is a transitional system.  All other modes of transport have a steady state mode of operation, where most parameters are static.
Now that is true, although it could be said that the stable orbit part is the "cruise" state.
Quote
Also, when power is removed, all other modes have graceful degradation.
You're extending assumptions and design decisions from one launch mode to another.

Let's unpack you're assumptions.
When an LV takes off vertically (IE Thrust must exceed GTOW) with no engine out capability and an engine fails it has no graceful degradation.

Which is true.

The corollary of which is a)Design in engine out capability and/or  b)Don't take off vertically.

There is also the subtle point that all 1st stage engines should be "equal," otherwise you get the Shuttle architecture where any engine failed at takeoff and you're doomed, although you're more doomed if one of the SRB failed, as they provided 90% of the T/O thrust.

These are design decisions, not laws of physics.

The fact something has always been done a certain way does not mean a)It's the best possible way and b)That other ways will compete or replace it.

This seems a very simple idea yet it seems almost impossible to explain to some people.  :(
Btw, I don't get the point why everybody here seems to assume that building and operating a space launch vehicle in the same entity would be something totally common just because that's how SpaceX and some other NewSpace companies are trying to do it. I mean... That's quite a new model, not even ULA has operated that way until now.
They're not.  Historically on paper there is actually an ELV building company and a launch services company. But (also historically) this has made no real difference as they are both parts of the same company.

I'd check the small print to see if those companies have a contract with "Space Exploration Inc" or something like "Space Exploration Launch Services Inc"

Only Sea Launch or Arianespace come near  the idea of a true separation between the mfg side and launch ops side.

Now the question is wheather it's difficult to have such a separation because it's orbital launch or because it's orbital launch conducted with basically an expendable weapons architecture.

Some think any orbital launch system is doomed to a mfg/operator,  others that it's the VTO ELV or attempted VTO semi RLV architecture that's the problem.  My view is that separation of tasks was not a design driver for ICBM's. REL's market analysis indicate there are a lot of people who want to launch payloads but don't want to fund an ELV to do so because they see no benefit in having yet another ELV, with it's usual 5% failure rate, destroyed after 1 use characteristics.

IOW they want an asset that gets the job done, not a development programme.
Quote
And strategic weapon systems are definitely not being operated by their manufacturers
But then they are delivered in orders of 100's,not ones and twos, and a few percent failure was anticipated, as they were designed to fight WWIII. At heart their ConOP was "Press button A to open silo, turn key at same time as partner (so one guy going nuts can't launch it) and press button B to launch"

Incidentally ICBM's also benefited from hghly  standardized payloads, which keep non recurring (but quite large) engineering costs down.

Hypersonic strategic air-lift anyone?
https://www.flightglobal.com/news/articles/uk-predicts-more-stealthy-and-stand-off-ops-by-2035-420125/
And possibly matter transmission and time travel as well.   :)

One of the skills in reading a govt report written by a civil servant keen to demonstrate a)How they've read everything on their subject or b) who is trying to advance a personal agenda is to spot "everything-but-the-kitchen-sink" sentences.

And let's keep in mind that right now most of the enemies the UK is in dispute with don't actually have an airforce, and their air defense weapons were mostly handed to them by the people the coalition of countries that the UK is a part of handed them to for their defense.  :(

Which suggests if the UK doesn't want to deal with advanced air defenses it shouldn't hand them to people who will turn them over to it's enemies at the first sign of trouble.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 12/17/2015 10:17 am
They're not.  Historically on paper there is actually an ELV building company and a launch services company. But (also historically) this has made no real difference as they are both parts of the same company.
"Historically", LVs have been built by companies and operated by NASA and the Air Force (SU had a somewhat different model).
For the last 25 years there have been private companies taking over the operator side and they have pretty much tried a broad range of different setups (Arianespace, ULA, LM, Boeing, ILS, Seal Launch, Orbital, SpaceX, each of them has or had a different business model).

Quote
Now the question is wheather it's difficult to have such a separation because it's orbital launch or because it's orbital launch conducted with basically an expendable weapons architecture.
It's not difficult because you have very little standardization and few launches. For Airline traffic you have tens of thousands of planes being operated by hundreds of airlines and specialized service organizations. Also with all kinds of different levels of vertical integration.

With Space Launch you have 10-20 launches per system per year and to build up 5 different organizations having the launch and service knowledge doesn't make an awful lot of sense.

If you have one Skylon it will be the same. 3 or 4, too.
If you have 100 Skylons it will surely happen.

In any case you can of course separate the build and launch organizations because you might or might not want to have a different structure depending on your preferences about vertical integration (Musk vs. McKinsey being the two extreme side of philosophies....)

Quote
But then they are delivered in orders of 100's,not ones and twos
Bingo. so it was easier to have a clear separation between manufacturer and operator. Just harder to compute with very few vehicles/launches so whatever your model you usually find yourself in a setup with only a few players.

As usual, it boils down to flight rates...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 12/17/2015 12:07 pm

As usual, it boils down to flight rates...

True, but over a period of 30 years. So assuming that the price of a Skylon vehicle is about 1bn Eur. if it flies only once in 30 years, then it is a 1b+operative costs flight. to compete with a partial reusable F9, assuming SpaceX is able to reduce costs down to 50% of F9, you need to compete in the range of 30M/launch.

If REL's own estimates on operative costs are correct, operative costs are about 5M/flight.  Which means that, over a period of 30 years, a single Skylon vehicle must fly about 40 times to compete with a partially reusable F9.
Which means a flight rate of about 1.3 per year.
NOT an impossible achievement I'd say....

Now, with 1 Bn pricetag, REL would need to sell about 20 Skylons in total to cover up expenses and realise a meaningful profit. in total, not simultaneously. Assuming they can sell it at a rate of 1 each 2 years, this means that, at the top of the curve, there will be a max of 15 skylons operating simultaneously.

Therefore, if F9-partialR remains the best competitor (assuming no inter-skylon competition, which is a bad assumption I aknwoledge), the total  Skylon fleet flight rate, at most, will require no more than 20 flights per year divided over a full fleet of 15 vehicles.

Again, not an impresive number.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 12/17/2015 12:25 pm
True, but over a period of 30 years.
A flight rate is a flight rate, no matter how long you maintain it.
You don't pay for maintaining a launch organization and infrastructure per launch (OK, you do if your flight rate is _really_ high but then we need no discussion here) but per year.

Quote
So assuming that the price of a Skylon vehicle is about 1bn Eur. if it flies only once in 30 years, then it is a 1b+operative costs flight.
Yep. But if it flies TWICE in 30 years, one today and once in 30 years, then the cost of keeping that infrastructure and team you don't need for 29 years _really_ kill you. Sorry, these extreme cases just get you nowhere in the discussion.

Quote
assuming SpaceX is able to reduce costs down to 50% of F9
Here, too, a static assumption makes little sense since this, too, will depend on the flight rate...

Quote
If REL's own estimates on operative costs are correct, operative costs are about 5M/flight.
If REL's own estimates are static they are wrong. Period. If they are not, we need to discuss flight rates.

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Which means that, over a period of 30 years, a single Skylon vehicle must fly about 40 times to compete with a partially reusable F9.
Even if that partially reusable F9 makes it's 10 flights in one year? No way. Keeping the team and infrastructure around for 30 years will be dramatically more expensive than having it for one year, your initial Skylon investment will pale in comparison. Especially now that interest is a thing again...

Quote
NOT an impossible achievement I'd say....
Completely impossible. The maintenance and operations will kill you, cost wise. Hangar, runway, payload handling facilities, fuel handling facilities, team, all of that for 1.3 flights a year? No way that's ever going to be economical.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/17/2015 12:31 pm
Now that is true, although it could be said that the stable orbit part is the "cruise" state.

No, that is completely separate and different.  Environments are different, control is different, etc.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/17/2015 12:39 pm
The same people that design the rocket are the same as ones doing integration and flight analysis.  The same people that buy off impacts from manufacturing discrepancies are the ones that buy off new launch environments. 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Space OurSoul on 12/17/2015 04:19 pm
I wonder if insurance costs would emerge from the noise at those projected launch costs.
Advantage Skylon, I think, since it would be demonstrably more likely that you'd get your payload back if the launch failed.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/17/2015 05:20 pm
Advantage Skylon, I think, since it would be demonstrably more likely that you'd get your payload back if the launch failed.

Same spin was used for the shuttle.  It would be worse.  What you get back is potentially damaged spacecraft filled with hazardous propellant.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: sghill on 12/17/2015 07:20 pm
Advantage Skylon, I think, since it would be demonstrably more likely that you'd get your payload back if the launch failed.

Same spin was used for the shuttle.  It would be worse.  What you get back is potentially damaged spacecraft filled with hazardous propellant.

And wings so small it's glide path would charitably be 4 to 1 if we use the X-15 as an example and 1 to 1 if we use the shuttle.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 12/17/2015 07:38 pm
Advantage Skylon, I think, since it would be demonstrably more likely that you'd get your payload back if the launch failed.

Same spin was used for the shuttle.  It would be worse.  What you get back is potentially damaged spacecraft filled with hazardous propellant.

And wings so small it's glide path would charitably be 4 to 1 if we use the X-15 as an example and 1 to 1 if we use the shuttle.

If it's designed to abort then presumably it can do so.  That has to have insurance value, doesn't really matter what one might think of it as a flying machine.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Space OurSoul on 12/17/2015 08:18 pm
Advantage Skylon, I think, since it would be demonstrably more likely that you'd get your payload back if the launch failed.

Same spin was used for the shuttle.  It would be worse.  What you get back is potentially damaged spacecraft filled with hazardous propellant.

I think it's fair to claim that shuttle and Skylon's returned payload would be equivalently damaged if there were a RUD in either case. Now, I'm not exactly a Skylon fanboi, but I think, if Skylon fulfills its design, some stronger claims could legitimately be made about less-catastrophic failure modes.
Skylon is intended (which I recognize is a heck of a long way from demonstrating) to provide intact abort-to-runway-landing throughout the early phase of launch, absent a RUD. Shuttle couldn't even have claimed let alone provided that. There's water on board whose sole purpose is brake cooling for abort before liftoff, and the required runway length is only that long so that it can enable these aborts. The tail is sized for coping with single-engine-cluster operation at low speed, so RTLS is designed to be possible at any point even with one whole nacelle out of action. It is designed to cruise (at Mach 3) on bypass ram engines alone, enabling intact abort to a wide range of destinations late in the launch phase even with both sets of rockets out of action.
But the most important point is that they plan 400 launches to orbit (200 for each prototype) before selling the first Skylon, and each individual instance is intended to receive 2 or 4 (forget the exact number) full flights before being delivered.
That history, both of the type and of the individual craft, plus all those intact abort modes to a benign runway landing, would allow a demonstrably reduced chance of loss of payload. Hence cheaper insurance when compared to vertical-takeoff, even when compared to a vertical-takeoff system with an equivalent flight history.
I think it is fair to argue, however, that the odds of one of these intact-abort scenarios are low enough that perhaps the advantage isn't that great.

(N00b argues with Jim. DUCK!)

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/17/2015 08:24 pm

plus all those intact abort modes to a benign runway landing,


What says an intact abort is a benign runway landing?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Space OurSoul on 12/17/2015 09:41 pm

plus all those intact abort modes to a benign runway landing,


What says an intact abort is a benign runway landing?

That's their design goal, at least.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 12/18/2015 12:54 am
There's an intriguing sentence here:

https://www.gov.uk/government/publications/future-operating-environment-2035

Quote
There are exciting prospects ahead for operational commanders who relish such challenges.  While these may appear
daunting, other developments may ease the task in hand.  Computer processing power has already been mentioned.  The commander may also be able to exploit lighter logistic chains, courtesy of additive printing, or perhaps even hypersonic
strategic air-lift.

:-)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/18/2015 09:24 am
Advantage Skylon, I think, since it would be demonstrably more likely that you'd get your payload back if the launch failed.

Same spin was used for the shuttle.  It would be worse.  What you get back is potentially damaged spacecraft filled with hazardous propellant.

And wings so small it's glide path would charitably be 4 to 1 if we use the X-15 as an example and 1 to 1 if we use the shuttle.
If you're talking about Skylon you should keep in mind that while those wings look small it is much better balanced than Shuttle, its fuselage is much more aerodynamic (no slab sides) and most of that shape (which will probably generate significant lift on its own) is empty.

It should be noted that most of the events and failure modes of a Shuttle launch simply don't happen in Skylon. I'm sure there will be a significant number of critical failure modes (as any complex vehicle has) An obvious concern being bird strikes to the inlets (discussed at great  length in earlier threads)

So what are people speculating on ? Logically FOD is an issue but methods exist to deal with that concern.

AFAIK there are no stats for damage to satellites on the Shuttle. It never happened.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/18/2015 09:25 am
There's an intriguing sentence here:

https://www.gov.uk/government/publications/future-operating-environment-2035

Quote
There are exciting prospects ahead for operational commanders who relish such challenges.  While these may appear
daunting, other developments may ease the task in hand.  Computer processing power has already been mentioned.  The commander may also be able to exploit lighter logistic chains, courtesy of additive printing, or perhaps even hypersonic
strategic air-lift.

:-)
Seen before. Already commented upon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 12/18/2015 10:25 am
It is designed to cruise (at Mach 3) on bypass ram engines alone, enabling intact abort to a wide range of destinations late in the launch phase even with both sets of rockets out of action.

Well I have been interested in Skylon for a long time and never come across that gem of info before. That's quite something. With all main engines out it can still propel itself with the bypass ramjets? Is this a fact?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/18/2015 12:01 pm


AFAIK there are no stats for damage to satellites on the Shuttle. It never happened.

No stats are required for shuttle.  The payloads were just required to survive an abort landing.  The capability to be operable after an abort landing is s different story.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Space OurSoul on 12/18/2015 10:34 pm
It is designed to cruise (at Mach 3) on bypass ram engines alone, enabling intact abort to a wide range of destinations late in the launch phase even with both sets of rockets out of action.

Well I have been interested in Skylon for a long time and never come across that gem of info before. That's quite something. With all main engines out it can still propel itself with the bypass ramjets? Is this a fact?

Well, I suppose there is some inference on my part that might not be warranted. There's a comment from an REL person in one of the videos where it's mentioned that it's expected to sustain Mach 3 "on the bypass burners alone", but granted that could very well mean merely that the burners produce enough thrust to do so, rather than meaning that it's a fully-supported mode of operation.


Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 12/19/2015 02:03 am
I believe that's part of the abort procedure for a failure early in rocket mode.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 12/19/2015 02:22 am
Uh, how far would it hobble Skylon operators to ban traditional toxic hypergols in payloads? Considering all the moves to electric thrusters as it is, what specific scenarios end up essentially needing hypergolic propellants? The missions that come to mind is any kind of short, high thrust scenario where a solid kick stage is undesirable, so some manned systems perhaps?
Almost every single spacecraft uses hypergols. Crewed, uncrewed, science, military, commercial, etc. All pretty much use hypergols (except a handful of special design).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Patchouli on 12/19/2015 04:27 am

Well I have been interested in Skylon for a long time and never come across that gem of info before. That's quite something. With all main engines out it can still propel itself with the bypass ramjets? Is this a fact?

Well, I suppose there is some inference on my part that might not be warranted. There's a comment from an REL person in one of the videos where it's mentioned that it's expected to sustain Mach 3 "on the bypass burners alone", but granted that could very well mean merely that the burners produce enough thrust to do so, rather than meaning that it's a fully-supported mode of operation.



[/quote]

Seems it's abort modes are a lot better then a VTOL rocket.
Such as being able to handle a rejected take off after roll and even make it to a landing site with half it's engines inoperative.
http://www.reactionengines.co.uk/tech_docs/JBIS_v57_22-32.pdf

Makes sense loose half your thrust on a conventional LV it's coming back down but since Skylon operates as an aircraft during the first part of it's flight an engine failure should be similar to other fixed wing aircraft.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/23/2015 06:55 am


AFAIK there are no stats for damage to satellites on the Shuttle. It never happened.

No stats are required for shuttle.  The payloads were just required to survive an abort landing.  The capability to be operable after an abort landing is s different story.
IIRC the 4 satellites of the Cluster mission that flew on the first Ariane 5 were re flown after recovery from the Guyianan jungle.

I would expect most Skylon failure modes to be more benign (in terms of acceleration and heating) than a 1st stage engine explosion and subsequent ELV RUD.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Archibald on 12/24/2015 09:47 am
I don't think so. Do you have a source for that claim ? I think they were completely destroyed and new spacecrafts had to be build. 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/24/2015 04:21 pm
1.  IIRC the 4 satellites of the Cluster mission that flew on the first Ariane 5 were re flown after recovery from the Guyianan jungle.

2. I would expect most Skylon failure modes to be more benign (in terms of acceleration and heating) than a 1st stage engine explosion and subsequent ELV RUD.

1.  Nonsense. 

2.  Meaningless comparison, because the payload in both cases is unusable.

There is a major difference in design for surviving an abort landing vs being a 100% capable of use after one.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alpha_Centauri on 12/24/2015 05:18 pm
I don't think so. Do you have a source for that claim ? I think they were completely destroyed and new spacecrafts had to be build. 
Yes new spacecraft were built; IIRC at least one was made using spare parts from the first mission which is perhaps the source of confusion.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Vultur on 12/24/2015 06:08 pm
Uh, how far would it hobble Skylon operators to ban traditional toxic hypergols in payloads? Considering all the moves to electric thrusters as it is, what specific scenarios end up essentially needing hypergolic propellants? The missions that come to mind is any kind of short, high thrust scenario where a solid kick stage is undesirable, so some manned systems perhaps?

There isn't "all the moves", it has only been GEO comsats that have done it.  The issue is for attitude control and not orbit changing.  Most spacecraft need thrusters with more power than electric ones.

Yeah. You'd have to talk spacecraft manufacturers into using less toxic propellants like hydrogen peroxide/something, hydrogen peroxide and the new "green" monoprops instead of hydrazine family/N2O4 and hydrazine.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Vultur on 12/24/2015 06:15 pm
They compute only a one-off count, not a recylce of the acquisition each 10 launches. Basically, it is like buying one skylon and using it 200 times, or buying a falcon 9 and using it 200 times. which is wrong.

Where does the assumption that a F9 first stage will only have a life of 10 flights come from? Is this a SpaceX number?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Elmar Moelzer on 12/24/2015 10:57 pm
They compute only a one-off count, not a recylce of the acquisition each 10 launches. Basically, it is like buying one skylon and using it 200 times, or buying a falcon 9 and using it 200 times. which is wrong.

Where does the assumption that a F9 first stage will only have a life of 10 flights come from? Is this a SpaceX number?
Indeed, last I heard Elon Musk was optimistic that a booster could be launched 20 times before major refurbishment would be necessary (like taking the stage apart and cleaning and checking every piece of it). I do not remember anything about 10 being the limit (even with refurbishment).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Dalhousie on 12/25/2015 12:07 am
They compute only a one-off count, not a recylce of the acquisition each 10 launches. Basically, it is like buying one skylon and using it 200 times, or buying a falcon 9 and using it 200 times. which is wrong.

Where does the assumption that a F9 first stage will only have a life of 10 flights come from? Is this a SpaceX number?
Indeed, last I heard Elon Musk was optimistic that a booster could be launched 20 times before major refurbishment would be necessary (like taking the stage apart and cleaning and checking every piece of it). I do not remember anything about 10 being the limit (even with refurbishment).

Probably his usual excessive optimism.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 12/25/2015 12:14 am
Probably there is no hard limit to what could be done.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Elmar Moelzer on 12/25/2015 03:13 am
Indeed, last I heard Elon Musk was optimistic that a booster could be launched 20 times before major refurbishment would be necessary (like taking the stage apart and cleaning and checking every piece of it). I do not remember anything about 10 being the limit (even with refurbishment).
Probably his usual excessive optimism.
Well, so far he has done everything he claimed he would do... taking a bit longer than anticipated but he did it.
Also I am sure that this estimate is based on their experiences gained during their engine test program and the grasshopper tests. So if he is not the one who is in the position to make a prediction about this, who is?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/25/2015 08:47 pm
I don't think so. Do you have a source for that claim ? I think they were completely destroyed and new spacecrafts had to be build. 
Yes new spacecraft were built; IIRC at least one was made using spare parts from the first mission which is perhaps the source of confusion.
I re-checked the history and indeed they did build a new group launched on a pair of Soyuz.

I had equated recovery with reuse. My mistake.
Yeah. You'd have to talk spacecraft manufacturers into using less toxic propellants like hydrogen peroxide/something, hydrogen peroxide and the new "green" monoprops instead of hydrazine family/N2O4 and hydrazine.
The question is how big a threat of leakage does a satellite pose if adequately sealed and how do other operators deal with these problem?
Probably there is no hard limit to what could be done.
Probably not, however there is likely a number of cycles where the probability of failure rises substantially, effectively the tail end of the "bathtub" reliability curve.

An interesting question would be if this remains the same regardless of payload size and wheather they are GSO or LEO missions.

Only time will tell what those numbers are will but they will have a major effect on how cost effective reuse can be for F9SR.
Well, so far he has done everything he claimed he would do... taking a bit longer than anticipated but he did it.
Not quite. He's eventually found a way to do most of what he's talked about. The original airbags + parachutes plan was abandoned. Upper stage reuse of the F9 (and FH) has also been abandoned.

While this is very pragmatic approach (something is better than nothing) the problem it demonstrates no clear path to the ultimate goal, or even that there is a clear path to it.
Quote
Also I am sure that this estimate is based on their experiences gained during their engine test program and the grasshopper tests. So if he is not the one who is in the position to make a prediction about this, who is?
While SX obviously has the best available data for their stage reuse Grasshopper had a key goal of working out how to land in the first place. It's structure and flight trajectories were so different there is little to connect the two vehicles.

10 or 20 is an informed guess.

When a 1st stage  flies that number of launches then they will be on much firmer ground.

Now could we return to discussing REL, SABRE and Skylon?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Vultur on 12/26/2015 01:39 am
Upper stage reuse of the F9 (and FH) has also been abandoned.

It was abandoned at one time, but there was IIRC a more recent comment (in one of the news articles on this site, IIRC) that that might no longer be the case in view of the satellite constellation.

(Musk said that it didn't make sense before because of the low Isp of kerolox and most payloads want GTO. But with a lot of LEO demand...)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 12/26/2015 02:16 am
THIS THREAD IS NOT ABOUT SPACEx!
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Vultur on 12/26/2015 02:24 am
True, but the question of Skylon's ability to attract enough investment to be built, and profitability if it is built and works, is strongly affected by what other reusable launch vehicles/systems are around.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/26/2015 05:59 am
True, but the question of Skylon's ability to attract enough investment to be built, and profitability if it is built and works, is strongly affected by what other reusable launch vehicles/systems are around.
Current answer. None.

Future answer. None.

SX have a superb PR machine but for most normal people "reusable" means fully reusable.

Getting a first stage of a 2 stage vehicle down is an amazing achievement, but (provided it can be re-flown) it's still half of a reusable rocket.

Changing the definition of a word to have a more limited meaning borrows from another Silicon Valley company, Microsoft. 

Do you want to view SX as the new Microsoft?  :(

Now can we return to a positive discussion of REL?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 12/26/2015 09:06 am
The "how does SpaceX compare to Skylon" discussion was relevant.
The "does Elon ever have to change plan" discussion is not (here).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/27/2015 07:08 am
The "how does SpaceX compare to Skylon" discussion was relevant.
The "does Elon ever have to change plan" discussion is not (here).
You're confusing SpaceX (the company) with Skylon (the vehicle)

But actually SX's changes of plan are very relevant to how these business differ.

SX has followed a fairly common Silicon Valley paradigm.

1)Create the system/software/whatever up to the difficult part
2)Hope that by then we've learned enough to figure a way to make the difficult part work
3)If we have, do it.
4)If not revise what we want to do or try and sell what we've got as it is.

REL's approach has been.
What is the vehicle needed to meet this market goal.
Work backward to find the engineering that can implement it.

One is bottom up, one is top down.

The difference is one delivers a working system early (IE an ELV) but might never deliver its ultimate goal. The 2nd delivers a working system at the end that will meet the end goal.

The first is a "bottom up" approach where the company "feels" it's way to it's goal. The second starts iwth the map and works out how to get the pieces needed to get there.

SX have built a superb ELV but Musk is adamant there will be no 2nd stage reuse. That's not an Apples to Apples comparison with Skylon. 

If you'd like a fair comparison between a true F9R and Skylon you'd have to

a)Give the F9 a reusable or "tug" stage like the SUS
b)Limit the F9 2nd stage to just need to get its payloads to LEO.
c)Make the 2nd stage survive and be reusable to the same planned limits as the 1st stage
d)Increase it's payload to LEO by about 1800Kg.
e)Allow the whole package to be purchased (and operated) by anyone not on the UN banned list.

That would make a true F9R a very interesting development in both the technical and the economic areas and might lower the normal cost / Kg by quite a lot, which is my key interest.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 12/27/2015 08:37 am
If you want a fair comparison Skylon first would have to fly.
And in a "Silicon Valley" approach you don't have a goal that you could reach or not reach, you just have a vision. That's a difference.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 12/27/2015 09:52 am
Getting a first stage of a 2 stage vehicle down is an amazing achievement, but (provided it can be re-flown) it's still half of a reusable rocket.

9 engines recovered out of ten. 80% of dry mass recovered.

But "half".

Changing the definition of a word to have a more limited meaning borrows from another Silicon Valley company, Microsoft.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/27/2015 11:56 am
If you want a fair comparison Skylon first would have to fly.
Definitely.
Quote
And in a "Silicon Valley" approach you don't have a goal that you could reach or not reach,
And hence a point at which investors can say you've succeeded or failed.   :)
Quote
you just have a vision. That's a difference.
I think you're confused by what that word means.

Believing we are close to being able to build a vehicle that can do HTOL SSTO (when the "smart" money says VTO TSTO is the safe way to go) and pursuing it is visionary.

Building a cheaper ELV? That's seems like the goal of every other aerospace startup since the 1980's.

Recovering and reusing the 1st stage? Every major aerospace contractor was talking about this in the 1960's and has been claiming they could do it (with enough funding of course  ;) ) ever since.  Implementing that goal has taken some ground breaking science and engineering.

Now Musk's ultimate goal, persuading a significant number of people to emigrate to Mars (and getting them to pay their way to do so  :) ), is visionary.

9 engines recovered out of ten. 80% of dry mass recovered.

But "half".
Economically it's more than 50% but operationally it's simply 1 stage of 2. With no chance of recovery of the 2nd, which will have to be replaced, versus a system where what goes up comes back down.
Quote
Changing the definition of a word to have a more limited meaning borrows from another Silicon Valley company, Microsoft.
Again semi reusable is not reusable.  Fully reusable is reusable.

I look forward to seeing SX's plans for the BFR, which they are now saying will be fully reusable.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: NovaSilisko on 12/27/2015 06:01 pm
THIS THREAD IS NOT ABOUT SPACEx!
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 12/28/2015 01:48 am
...

Believing we are close to being able to build a vehicle that can do HTOL SSTO (when the "smart" money says VTO TSTO is the safe way to go) and pursuing it is visionary....
...who is pursuing it with whose army? I just see some R&D money, a few battleship pressure-fed rocket engine tests (not much more than amateur level) and a heat exchanger (which I'm told they don't even need for their new design). Nothing about a HTOL vehicle prototype, let alone one near SSTO performance.

...additionally, Skylon is practically TSTO anyway, since almost all commercial payloads of note are GSO.

Lots of people have had ideas for RLVs, even SSTO and horizontally landing ones. So far, Skylon isn't even as far as X-33, nor do I see evidence that they'll get that far.

Europe, please prove me wrong.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Lars-J on 12/28/2015 05:03 am

SX has followed a fairly common Silicon Valley paradigm.

1)Create the system/software/whatever up to the difficult part
2)Hope that by then we've learned enough to figure a way to make the difficult part work
3)If we have, do it.
4)If not revise what we want to do or try and sell what we've got as it is.

REL's approach has been.
What is the vehicle needed to meet this market goal.
Work backward to find the engineering that can implement it.

One is bottom up, one is top down.

The difference is one delivers a working system early (IE an ELV) but might never deliver its ultimate goal. The 2nd delivers a working system at the end that will meet the end goal.

I see what you did there. :) So there is no risk at all in the 2nd approach? You forgot to add this: ... But it might never deliver anything at all.

But if that really is your opinion, then it explains a great deal about your cheerleading for Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/28/2015 06:08 am
I see what you did there. :) So there is no risk at all in the 2nd approach? You forgot to add this: ... But it might never deliver anything at all.
You seem to have a very short memory.

I've repeatedly stated that SABRESkylon is a high risk/cost/reward project. 

Why would expect something the size of Airbus A380 to be less to build than A380?
Quote
But if that really is your opinion, then it explains a great deal about your cheerleading for Skylon.
Why don't you explain "my opinion" to me. I'd love to see the outsiders view.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 12/28/2015 02:19 pm
...

Believing we are close to being able to build a vehicle that can do HTOL SSTO (when the "smart" money says VTO TSTO is the safe way to go) and pursuing it is visionary....
...who is pursuing it with whose army? I just see some R&D money, a few battleship pressure-fed rocket engine tests (not much more than amateur level) and a heat exchanger (which I'm told they don't even need for their new design). ....

They do need their heat exchanger even in their new design - they simply won't need to drop the temperature as much if they use SABRE4  and therefore won't need the anti-freeze system.  It's difficult to discuss when basic inaccuracies keep slipping in.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 12/29/2015 02:38 am
...

Believing we are close to being able to build a vehicle that can do HTOL SSTO (when the "smart" money says VTO TSTO is the safe way to go) and pursuing it is visionary....
...who is pursuing it with whose army? I just see some R&D money, a few battleship pressure-fed rocket engine tests (not much more than amateur level) and a heat exchanger (which I'm told they don't even need for their new design). ....

They do need their heat exchanger even in their new design - they simply won't need to drop the temperature as much if they use SABRE4  and therefore won't need the anti-freeze system.  It's difficult to discuss when basic inaccuracies keep slipping in.
I appreciate the correction, but the essence of what I meant stands: I remember a big deal being made of their fancy demoed heat exchanger that can prevent icing, but you say now it's not needed.

Just skepticism. I've seen too many things that are studied to death or a few low-level tests and then nothing. I want them to actually BUILD a vehicle. I like the idea of their battleship demo vehicle that I heard here. Anything like that would be better than now.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/29/2015 06:29 am
I appreciate the correction, but the essence of what I meant stands: I remember a big deal being made of their fancy demoed heat exchanger that can prevent icing, but you say now it's not needed.
Your memory needs a little correction. The big deal about the REL HX technology is twofold It does not clog with ice (which they tested) and it's phenomenal power to weight ratio (IE power extracted from the airflow), which AFAIK they've also tested since the test unit was a full size module of the SABRE design.

The equivalent capacity HX used by nuclear power stations (such as the ones on the Nimitz class carriers for example, where weight is a factor) weigh 200 tonnes.

That's a 100-200:1 improvement.
Quote
Just skepticism. I've seen too many things that are studied to death or a few low-level tests and then nothing. I want them to actually BUILD a vehicle. I like the idea of their battleship demo vehicle that I heard here. Anything like that would be better than now.
Then we're all in complete agreement.  :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Kharkov on 12/29/2015 07:10 am
...

Believing we are close to being able to build a vehicle that can do HTOL SSTO (when the "smart" money says VTO TSTO is the safe way to go) and pursuing it is visionary....
...who is pursuing it with whose army? I just see some R&D money, a few battleship pressure-fed rocket engine tests (not much more than amateur level)... (snip)
I'm sorry, I've been doing my best to follow this thread but I think I missed a turn there.

"...a few battleship pressure-fed rocket engine tests..."?

I hope this isn't out of turn but could somebody explain that last bit?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/29/2015 07:45 am
I'm sorry, I've been doing my best to follow this thread but I think I missed a turn there.

"...a few battleship pressure-fed rocket engine tests..."?

I hope this isn't out of turn but could somebody explain that last bit?
he's referring to the series of uncooled engines REL have used to refine their design. These have typically been made from solid lumps of metal and are therefor quite heavy. Hence the term "battleship," as opposed to "flight weight."
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 12/29/2015 05:44 pm
Or a rocket powered Battleship! Lets face it that HAS to have some 'cool-is-the-rule' points :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 12/29/2015 08:21 pm

The question is how big a threat of leakage does a satellite pose if adequately sealed and how do other operators deal with these problem?


They are never "sealed".  There is always a chance of a leak.  The mitigation is to limit personnel exposure.  Only those necessary in performing work on the vehicle are allowed near the vehicle.  Hence, there are no offices facilities containing spacecraft loaded with propellants.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 12/29/2015 10:25 pm
Or a rocket powered Battleship! Lets face it that HAS to have some 'cool-is-the-rule' points :)

Randy
Oh that's Niven and Pournell's "Footfall."  :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 01/01/2016 10:10 am
So, with SpaceX demonstrating first stage return and soon performing a static fire test with zero extra refurbishment, can we call the reusability space race on?

this has implications for Skylon. Huge implications, I believe: it is the only design out there which could compete, in the long run, with spaceX. Wouldn't you look at it if you were in the governing body of some classical launching providers starting to feel the heat?

(happy new year to all!)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 01/01/2016 01:06 pm
So, with SpaceX demonstrating first stage return and soon performing a static fire test with zero extra refurbishment, can we call the reusability space race on?

this has implications for Skylon. Huge implications, I believe: it is the only design out there which could compete, in the long run, with spaceX. Wouldn't you look at it if you were in the governing body of some classical launching providers starting to feel the heat?

(happy new year to all!)

Sadly I seem to have learned form all this that the only re-usability private might be willing to fund is 'doing something like SpaceX'.  Is it realistically only the U.S. or Europe (govt agencies) who might take it further on the grounds that it is important new technology to be developed for all - or technology that would give an edge?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: QuantumG on 01/01/2016 10:08 pm
Nah, there's plenty of money available for a venture like this.. you just have to come up with a business plan that scales. There's a reason why there's a dozen different smallsat launch startups.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Darkseraph on 01/01/2016 10:41 pm
BAE systems is primarily a defense company and I am guessing their substantial investment in developing the SABRE engine technology is more related to its military applications. These technologies being used for hypersonic UAVs strikes me as being more likely than SKYLON or Concorde 2.0. 

For that reason, I don't think the success of Falcon9R will dent the development of SABRE engine.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 01/01/2016 11:51 pm
I think F9R's success so far, on balance, gives Skylon a better shot than it otherwise would.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 01/02/2016 09:07 am
I think F9R's success so far, on balance, gives Skylon a better shot than it otherwise would.

Yes, I agree with you. Also, if BAE is really mainly interested in defense, they would not oppose a partnership with different companies which are not their direct competitors in the defense sector. This, of course, excludes LM and therefore ULA; but they are not the only players in town.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 01/03/2016 06:12 pm
Sad news from REL at the end of 2015:

Quote
John Scott-Scott, one of the three founders of Reaction Engines, passed away in the early hours of Saturday 12th December 2015.
 
This marked the passing of a truly remarkable aerospace engineer. Thanks in no small part to John’s tireless work, Reaction Engines now enjoys recognition by both Government and Industry through strong partnerships with BAE Systems, and the UK and European Space Agencies. This success is a tribute to John, his incredible abilities and his perseverance.

http://www.reactionengines.co.uk/about_history_john_scott-scott.html
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 01/03/2016 06:31 pm
Several posts back Jim pointed out problems with the way Skylon ground ops are depicted in REL animations. We have heard before that the animations are just 'illustrative', for example showing A380s in the vicinity in order to show scale, not that there would be any at the sapceport. That started me thinking about what real ground ops might be like; what are the informed guesses we can make.

I'll throw out a couple: how will startup hydrogen burnoff, and static fire be handled?

1] Presumably Skylon's SABRE's would need some sort of sparkler to safely burn any hydrogen that's released during startup and/or aborted startup. Given that we think the Skylon will be fueled while on the runway, it will need to be positioned precisely over the fueling stations, and so the SABRE's could line up with fixed sparklers built at the end of the runway?

2] For static fire, I suppose you would have to build hard points into the SABRE's that mate to a fixed structure at the end of the runway. I doubt the runway material could endure the plume from a full duration test, including transition to rocket mode, so I think you'd need to excavate a large volume to accommodate this. (Just make sure a landing Skylon doesn't overshoot and nosedive into it...)

But if you didn't need a full duration test, a much simpler solution could be to just let Skylon roll down the runway unhindered. It's long enough to allow for a fairly long burn and then a leisurely braking afterwards.

What else?

http://www.reactionengines.co.uk/vid_skylonops.html
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Rocket Science on 01/03/2016 06:32 pm
Respects to an aerospace pioneer.... May he rest in peace...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/03/2016 09:52 pm
1] Presumably Skylon's SABRE's would need some sort of sparkler to safely burn any hydrogen that's released during startup and/or aborted startup.
It's usually called a flare stack and the ignitor is basically a spark plug. However REL's COP is to load and launch within 2 hrs or recycle the propellants to long term storage. By pre cooling the hardware and the propellants they expect zero boiloff under normal operation. An aborted takeoff is probably the most challenging, but I guess the question is how do current transport aircraft handle it? AFAIK they get the crew off ASAP and then unload the fuel and otherwise "safe" the vehicle, usually with a fair amount of fire retardent foam.
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Given that we think the Skylon will be fueled while on the runway,
Not quite. REL state they expect to do this at a specific "hard stand" area. To reduce the number of skin penetrations the drain/fill connectors are planned to be in the wheel wells, with automated refueling. Given UAV's have demonstrated in flight refuelling this should be fairly straightforward given a combination of grooves in the concrete and compliant couplings.
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it will need to be positioned precisely over the fueling stations, and so the SABRE's could line up with fixed sparklers built at the end of the runway?
No boil off means no burn off.
Quote
2] For static fire, I suppose you would have to build hard points into the SABRE's that mate to a fixed structure at the end of the runway. I doubt the runway material could endure the plume from a full duration test, including transition to rocket mode, so I think you'd need to excavate a large volume to accommodate this. (Just make sure a landing Skylon doesn't overshoot and nosedive into it...)
This is for VTO ELV's. AFAIK aircraft do some short full thrust tests before brake release.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 01/04/2016 01:14 am
JCRM: thanks for that. There is indeed a description of operations and even a draft spaceport layout on page 15 of IAC-14.D2.4.5: https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36826.0;attach=1083478

There's no mention of long duration static fire, just that full-thrust will be verified before committing to launch - when brakes are released. Evidently they're good brakes  :)

The runway has a 'starter strip' that's designed to withstand greater heating, as well as another toughened region where Skylon rotates.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/05/2016 08:18 am
There's no mention of long duration static fire, just that full-thrust will be verified before committing to launch - when brakes are released. Evidently they're good brakes  :)
They will be.

Outside nosecones and leading edges for orbital vehicles big aircraft brakes seems to have been the success story for Reinforced Carbon Carbon materials.

Keep in mind at this point the brakes are stopping Skylon to start moving. Later on they have to deal with its momentum, which is much higher, hence the water cooling.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/05/2016 08:33 am
Hopefully it will lay to rest some of the "It's not possible to reuse a launch vehicle without months and millions spent on refurbishment" doubts some have, but perhaps we have to wait until someone manages to reuse a second stage.
Well half a launch vehicle at any rate.

The real question is does this lower the $/Kg price to orbit.

My numbers for F9SR suggest probably not enough to matter.  :(

Only the Skylon design and business model (currently) delivers the freedom of launch base, launch supplier and launch schedule that could do makes a global launch market a reality.
Quote
Once fully reusable  launch vehicles have been achieved, how long will expendables be allowed to continue - with viable alternatives, are people going to carry on accepting the necessity of falling COPVs? (or will they be fine, until something important is hit by one, at which point it will be an unacceptable risk that must never be allowed again?)
The COPV for the F9 stage was inside the tank most of the time.

If you mean a COPV as a solid fuel SRB or stage then you're really talking about ICBM technology, which people will want regardless, because they want long term silo storage with launch on demand and accept the poor Isp in return because they want the ability to flash fry their enemies.   :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/05/2016 09:41 am
Yes, I agree with you. Also, if BAE is really mainly interested in defense, they would not oppose a partnership with different companies which are not their direct competitors in the defense sector. This, of course, excludes LM and therefore ULA; but they are not the only players in town.
For some time now it's looked like Finance is the key issue for moving SABRESkylon forward.

REL is not an aircraft builder but wants to get (a kind of) an aircraft built so it can be a sub contractor to the builder.

This makes raising funding for the current generation of work very tricky, despite (as REL point out) 94 countries having a national space agency, along with (as 2015) 1800 billionaires.

These facts suggest there is a substantial group of people and organizations who want (or could afford) a part or all of a fully reusable (and re saleable) system that could give them on demand access to LEO and (if wanted) GEO.

The challenge is how to get those organizations to legally commit to buying a system that does not yet exist to be manufactured by an organization that also does not exist yet.  :(

This has certainly been done in the past for large capital goods like mainframe computers and aircraft and has been critical  in allowing the companies to approach banks for funding for the development.

The novel aspects of this would be a)REL is acting as an "agent" for an organization that has not been formed yet. Indeed the existence of the commitments would encourage its formation to begin with. b)There have to be safeguards on cost and schedule so no (expected) purchase would have an unlimited price to pay at an indefinite time in the future. This suggests inflation and time clauses. If a consortium can't do it in the time and the maximum price then the organization has to buy nothing, although it if wants one after that it would then have to pay open market price for it (assumed Skylon was developed eventually).

Enough such signings would give REL a pool of confirmed sales the consortium would have at it's disposal provided it can deliver Skylon within the limit and make an adequate profit at the contract price at the time of delivery. That in turn gives incentives to get companies to join the consortium (based on their assessment of REL and their own abilities to deliver their parts) and that in turn gives funding organizations confidence to commit funds (based on their assessment of the consortium members financial and implementation track records).

It's a weird idea that a company (REL) creates such an asset (a pool of commitments) to transfer to another company that does not yet exist yet to facilitate its future growth. "Bootstrap" financing of both the consortium and the banks ?

The problem is it's a business solution and while I have no doubts about REL's technical competence I'm not sure they have anyone who's raised funds on this sort of scale in a commercial (IE from banks, not direct government funding, as in defense projects) environment.   :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 01/07/2016 10:24 pm
Yes, I agree with you. Also, if BAE is really mainly interested in defense, they would not oppose a partnership with different companies which are not their direct competitors in the defense sector. This, of course, excludes LM and therefore ULA; but they are not the only players in town.
For some time now it's looked like Finance is the key issue for moving SABRESkylon forward.

REL is not an aircraft builder but wants to get (a kind of) an aircraft built so it can be a sub contractor to the builder.

This makes raising funding for the current generation of work very tricky, despite (as REL point out) 94 countries having a national space agency, along with (as 2015) 1800 billionaires.

These facts suggest there is a substantial group of people and organizations who want (or could afford) a part or all of a fully reusable (and re saleable) system that could give them on demand access to LEO and (if wanted) GEO.

The challenge is how to get those organizations to legally commit to buying a system that does not yet exist to be manufactured by an organization that also does not exist yet.  :(

This has certainly been done in the past for large capital goods like mainframe computers and aircraft and has been critical  in allowing the companies to approach banks for funding for the development.

The novel aspects of this would be a)REL is acting as an "agent" for an organization that has not been formed yet. Indeed the existence of the commitments would encourage its formation to begin with. b)There have to be safeguards on cost and schedule so no (expected) purchase would have an unlimited price to pay at an indefinite time in the future. This suggests inflation and time clauses. If a consortium can't do it in the time and the maximum price then the organization has to buy nothing, although it if wants one after that it would then have to pay open market price for it (assumed Skylon was developed eventually).

Enough such signings would give REL a pool of confirmed sales the consortium would have at it's disposal provided it can deliver Skylon within the limit and make an adequate profit at the contract price at the time of delivery. That in turn gives incentives to get companies to join the consortium (based on their assessment of REL and their own abilities to deliver their parts) and that in turn gives funding organizations confidence to commit funds (based on their assessment of the consortium members financial and implementation track records).

It's a weird idea that a company (REL) creates such an asset (a pool of commitments) to transfer to another company that does not yet exist yet to facilitate its future growth. "Bootstrap" financing of both the consortium and the banks ?

The problem is it's a business solution and while I have no doubts about REL's technical competence I'm not sure they have anyone who's raised funds on this sort of scale in a commercial (IE from banks, not direct government funding, as in defense projects) environment.   :(

No worries! The guys who handle the excellent PR for REL are the ones handling the direct business work... Oh... wait...

Seriously it's scary at times when you really think about RELs position and the fact they've gotten as far as they have. Ahh well, it's another year so here comes 12 more months of Opportunity! (And Spirit, and opportunity even but this is about Skylon :) )

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/08/2016 09:48 am
No worries! The guys who handle the excellent PR for REL are the ones handling the direct business work... Oh... wait...
Indeed the REL PR team is trying. I've sometime viewed their efforts and thought "this is very trying."  :)
Quote
Seriously it's scary at times when you really think about RELs position and the fact they've gotten as far as they have. Ahh well, it's another year so here comes 12 more months of Opportunity! (And Spirit, and opportunity even but this is about Skylon :) )

Randy
True. Nice to see you posting again. It seems like it's been an age.  :)

I'm a great believer in the idea that chaos creates opportunity and I'm hoping the coming year may generate enough for some investors to start looking round and asking themselves "Who's got a well developed plan to deliver a better solution and who's demonstrated the ability and stamina to execute when fully funded?"

Provided REL can recognize when such opportunities are offered and take advantage of them.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/11/2016 07:13 am
Quote from: http://www.reactionengines.co.uk/press_release/2015-12-28_Chris_Allam_Appointment_FINAL.pdf
The Board of Reaction Engines Ltd is pleased to announce the appointment of Chris Allam, Engineering Director at BAE  Systems,  as  a  Director  of  the  Company. His  appointment  is  part  of  the  strategic investment and working partner relationship BAE Systems has entered into with Reaction Engines and he will co-ordinate BAE Systems’ collaboration on Reaction Engines’ development of its SABRE™ engine.

[...]
Previous roles within BAE Systems include Senior Vice President of F-35 Lightning II (2011), Managing Director  of  Autonomous  Systems  and  Future  Capability  (2008), and Project Director for Unmanned Air Vehicles within BAE Systems’ Future Systems division (2006)
So, some experience with developing new technologies?
He's clearly part of the price for the BAe investment.

His resume looks like he's some experience with UAV's which is obviously important but BAe's history with in house developed UAV's has not been impressive (Watchkeeper, anyone?)

As for the F35 the last estimate I saw was it was around 7 years late and $168 billion over budget.
IE Skylon could be built for about 8% of the cost overrun on the programme.

That makes him quite skilled at telling governments why they are not getting what they wanted for the price they wanted it at the time they expected it (and BTW could we have some more money please).

Is this the skillset you need for raising funds in a commercial background? Probably not. Does that mean REL are going to go 100% government funding? I hope not

REL have shown they are very smart engineers. I just hope their staff selection skills are as well developed.  :(

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 01/11/2016 02:57 pm

Quote from: http://www.reactionengines.co.uk/press_release/2015-12-28_Chris_Allam_Appointment_FINAL.pdf
The Board of Reaction Engines Ltd is pleased to announce the appointment of Chris Allam, Engineering Director at BAE  Systems,  as  a  Director  of  the  Company. His  appointment  is  part  of  the  strategic investment and working partner relationship BAE Systems has entered into with Reaction Engines and he will co-ordinate BAE Systems’ collaboration on Reaction Engines’ development of its SABRE engine.

[...]
Previous roles within BAE Systems include Senior Vice President of F-35 Lightning II (2011), Managing Director  of  Autonomous  Systems  and  Future  Capability  (2008), and Project Director for Unmanned Air Vehicles within BAE Systems’ Future Systems division (2006)
So, some experience with developing new technologies?
He's clearly part of the price for the BAe investment.

His resume looks like he's some experience with UAV's which is obviously important but BAe's history with in house developed UAV's has not been impressive (Watchkeeper, anyone?)

As for the F35 the last estimate I saw was it was around 7 years late and $168 billion over budget.
IE Skylon could be built for about 8% of the cost overrun on the programme.

That makes him quite skilled at telling governments why they are not getting what they wanted for the price they wanted it at the time they expected it (and BTW could we have some more money please).

Is this the skillset you need for raising funds in a commercial background? Probably not. Does that mean REL are going to go 100% government funding? I hope not

REL have shown they are very smart engineers. I just hope their staff selection skills are as well developed.  :(

So are you blaming BAE for the issues with the F-35 program because to me that's quite clearly very little to do with them. Also it is rather past history being as the program is now on track.

As for the comments about UAVs, again though it maybe only a technology demonstrator I would say their experience with delivering the Taranis is far more applicable here than the Watchkeeper program.

In fact I find the whole of your commentary here to be pretty unwarranted and little to do with the topic at hand.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/12/2016 01:05 pm
So are you blaming BAE for the issues with the F-35 program because to me that's quite clearly very little to do with them.
This suggests they are quite deeply integrated into the programme

http://www.globalsecurity.org/military/systems/aircraft/f-35-bae.htm

Certainly cost questions have been raised on the "autonomic logistics" system which is part of their remit to the point where the DoD have put this part of the work out to open tender.

Quote
Also it is rather past history being as the program is now on track.
That's fine where the customers a government and this sort of re-scoping is SOP when things go wrong but in the commercial field 7 years late is 7 years late. Not to mention the little matter of how it got to be 7 years late.
Quote
As for the comments about UAVs, again though it maybe only a technology demonstrator I would say their experience with delivering the Taranis is far more applicable here than the Watchkeeper program.
Taranis seems impressive (given what little's been released about it) and just 28% over budget.
I don't think that's particularly good by commercial funding standards.

I found it interesting that BAe asked for preferred supplier status in addition to their seat on the Board. You wonder what systems that was for and suspect REL could get better with an open tender.
Quote
In fact I find the whole of your commentary here to be pretty unwarranted and little to do with the topic at hand.
Wow. I really seem to have hit a raw nerve with you. My apologies.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 01/12/2016 01:42 pm
John, you may be looking at this the wrong way I think :)

Going over his resume presented again:
"Previous roles within BAE Systems include Senior Vice President of F-35 Lightning II (2011), Managing Director  of  Autonomous  Systems  and  Future  Capability  (2008), and Project Director for Unmanned Air Vehicles within BAE Systems’ Future Systems division (2006)"

I suspect REL/BAE are more interested in his experience with automated flight systems and "future capability/systems" than his overall experience with the F-35. (Though to be honest, one of the criteria for the on-board systems of the F-35 is fully automated take-offs and landing capability and supposedly automated refueling capability)

Considering that the Skylon is supposed to operate autonomously as a UAV for most operations I suspect "that" is the reasoning behind the appointment AND relationship with BAE.

I fully expect that this is also in-line with RELs attempts to get the government more interested in their work and to help secure funding both government and private.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 01/12/2016 03:14 pm

John, you may be looking at this the wrong way I think :)

Going over his resume presented again:
"Previous roles within BAE Systems include Senior Vice President of F-35 Lightning II (2011), Managing Director  of  Autonomous  Systems  and  Future  Capability  (2008), and Project Director for Unmanned Air Vehicles within BAE Systems’ Future Systems division (2006)"

I suspect REL/BAE are more interested in his experience with automated flight systems and "future capability/systems" than his overall experience with the F-35. (Though to be honest, one of the criteria for the on-board systems of the F-35 is fully automated take-offs and landing capability and supposedly automated refueling capability)

Considering that the Skylon is supposed to operate autonomously as a UAV for most operations I suspect "that" is the reasoning behind the appointment AND relationship with BAE.

I fully expect that this is also in-line with RELs attempts to get the government more interested in their work and to help secure funding both government and private.

Randy

I suspect you're on the right track with your final paragraph. The chance of this project getting off the ground without some kind of governmental financial support has looked increasingly slim to me as time has gone on.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 01/12/2016 05:39 pm
I suspect you're on the right track with your final paragraph. The chance of this project getting off the ground without some kind of governmental financial support has looked increasingly slim to me as time has gone on.

Well it's not a given though as REL and others have been pointing out :) The problem (again as REL and others have been pointing out) is that government support is elusive, fickle, and more often than not less help than hindrance, but this being a "launch vehicle" the expectation is there that at some point the government has to give it its blessings.

In truth this kind of project CAN be undertaken strictly as a private venture but the perception is there and can't be ignored. On the converse side, you have to take into account the "positive" attitude shown by "the government" both at home and abroad and figure that alone is a pretty good indication that "someone" thinks the project worth supporting.

But REL is an engine design/manufacturer with a unique product that needs to have others become partners in order to see a complete product. This is FAR from the first time such circumstances have happened and I, personally think that today's environment would seem to give a better chance of success than any time prior. But I look at the history of the SERJ (supercharged-ejector-ramjet) engine and other "innovative" air-breathing systems that failed to fly for lack of government interest, intermittent support, or numerous other factors and I can't at all fault RELs emphasis on not DEPENDING on the government if they can at all help it.

Lacking a dedicated angel investor or consortium of investors they may indeed have to turn directly to the government, a government, but they've managed a lot more than a lot of people ever thought they would already :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/13/2016 12:23 pm
Considering that the Skylon is supposed to operate autonomously as a UAV for most operations I suspect "that" is the reasoning behind the appointment AND relationship with BAE.
That's reasonable but I'm very weary of why BAe wanted "preferred supplier" status on some systems, and what they are.

Yes automated takeoff and landing is tricky but the X10 demonstrated autonomous landing in the late 50's and the first blind landing of a commercial aircraft took place in 1964. I think it's pretty clear that a takeoff or landing from a floating runway (pretty much the worst case scenario) is never going to happen outside a Bond movie.   :)
 
Skylon will pose unique problems given it's size and stiffness but I find it very hard to believe BAe has a unique skillset in this area. Uncommon, but not unique.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 01/13/2016 12:33 pm
That's reasonable but I'm very weary of why BAe wanted "preferred supplier" status on some systems, and what they are.
{snip}

BAE Systems were makers of airframes where as Reaction Engines are engine makers. There is an obvious match there. Rolls Royce produce aircraft engines but do not produce entire aircraft. BAE Systems could also supply the avionics.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 01/13/2016 01:16 pm
Taranis seems impressive (given what little's been released about it) and just 28% over budget.
I don't think that's particularly good by commercial funding standards.

The whole point of military projects is to make the less known and less predictable stuff known and predictable for commercial projects. Hence why it's important to snaffle someone who has been through it and has the experience to do it better or at least more predictably next time.

Watchkeeper is a Thales project BTW, not BAE.

What projects other than Taranis and Watchkeeper have their been in the UK? Which of those is most relevant? I suggest Taranis because it seems to be a much more complicated vehicle with unusual propulsion and control problems and an ultimately more ambitious direction.  It's also a sort of culmination of other work, not very glamorous stuff but indicative that BAE have not appeared in unmanned aviation totally out of the blue. New aircraft projects don't seem to be very common in the UK - I'd have imagined that getting people who have that experience is exceedingly valuable.


Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 01/13/2016 01:19 pm
SpaceNews Reports that the European Commission intends to develop a European reusable rocket, the decision to be made by 2020 in order to get funding in the 2021-2028 budget. No citation of Skylon, but lot of worries in traditional EU space circles reported.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Oli on 01/13/2016 03:45 pm
No citation of Skylon, but lot of worries in traditional EU space circles reported.

Nope, worries among EU politicians reported.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 01/13/2016 04:40 pm
... I think it's pretty clear that a takeoff or landing from a floating runway (pretty much the worst case scenario) is never going to happen outside a Bond movie.   :)

It's essentially OT, but why are you so skeptical about autoland? Perhaps you know something about things like X-47B carrier landing tests that we don't? I'm more cautious than most about automated landing (especially vertical landings in wind/wind-shear) but SpaceX and Blue are on the way to convincing me that control systems are getting pretty darn good.

For Skylon, we can guess that they'll be cautious about not landing in problematic weather, just as happened with the Shuttle.

https://www.youtube.com/watch?v=1gG-EFqrndM
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/13/2016 04:54 pm
It's essentially OT, but why are you so skeptical about autoland?
I'm not. Try to read what I wrote. Then compare the size of Skylon with any of the UAV's that have demonstrated a carrier deck landing.

Now consider how big that carrier would have to be to accommodate a Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 01/13/2016 05:16 pm
It's essentially OT, but why are you so skeptical about autoland?
I'm not. Try to read what I wrote. Then compare the size of Skylon with any of the UAV's that have demonstrated a carrier deck landing.

Now consider how big that carrier would have to be to accommodate a Skylon.

Fun fact: you seem to read all question directed to you as if they're trying make you sound foolish. Its not the case. You seem to be privy to some hard-to-find information, and I wondered if you could tell me something I didn't know. I could well believe the X-47B tests exposed challenges that are not widely known.

And when you suggest we don't have the necessary reading comprehension skills to interact with you, guess how that sounds.

And why on earth are we talking about landing Skylon on a carrier? Let's move on.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Archibald on 01/13/2016 06:56 pm
Bring back project habakkuk 
 https://en.wikipedia.org/wiki/Project_Habakkuk
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/13/2016 09:54 pm
Fun fact: you seem to read all question directed to you as if they're trying make you sound foolish. Its not the case.
No. In this case I think the question makes the questioner sound foolish, although I'll admit I'm assuming English is a first language for you. If not it might have made more sense to you in your native language.
Quote
You seem to be privy to some hard-to-find information, and I wondered if you could tell me something I didn't know. I could well believe the X-47B tests exposed challenges that are not widely known.
No idea. AFIK they went pretty well. A bit too well in fact for senior Naval officers who would like to feel that only "Naval Aviators" have the skills to do carrier landings.
The point I was trying to make, which you don't seem to understand, is carrier landings are a known hard task for UAV's. My point is "so what?" The so what is due to the fact no Skylon is going to do a carrier landing. 
Quote
And why on earth are we talking about landing Skylon on a carrier? Let's move on.
Certainly
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 01/13/2016 10:33 pm
Here's what I heard you say: 1] Autoland is easy 2] apart from carrier landings, which only happen in Bond movies 4] even though carrier landings - a known hard case - have been demonstrated successfully, but 5] it's a waste of time talking about the difficulty of landing UAV's on carriers because Skylon won't land on one.

...I'm certainly a fool for wasting my time in this thread.

Despite the bizarre tangents, everyone seems to agree the pilotless aspect of Skylon is not a big deal.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 01/14/2016 02:39 am
SpaceNews Reports that the European Commission intends to develop a European reusable rocket, the decision to be made by 2020 in order to get funding in the 2021-2028 budget. No citation of Skylon, but lot of worries in traditional EU space circles reported.
Very good news, but 2020??? "After we've lost all of our commercial payloads to SpaceX and maybe ULA and Blue Origin, we'll decide to develop a reusable rocket."

Anyway, please link when reporting a news item or really any new information!
Because what I do see does not seem to be exactly what you claim:
http://spacenews.com/brunet-european-commission-should-have-hand-in-designing-next-gen-rocket/
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/14/2016 08:47 am
Very good news, but 2020??? "After we've lost all of our commercial payloads to SpaceX and maybe ULA and Blue Origin, we'll decide to develop a reusable rocket."

Anyway, please link when reporting a news item or really any new information!
Because what I do see does not seem to be exactly what you claim:
http://spacenews.com/brunet-european-commission-should-have-hand-in-designing-next-gen-rocket/
You're right.

It's interesting that the EU has spent several years giving the ELV design teams greater autonomy to say "This is what we think will work."

That got the all solid A6 design.

I think non Europeans have real trouble understanding how the ELV design process works. In particular

EU <> EU Parliament <>EU Commission <> ESA <> CNES <> Arianspace.

They are all distinct industrial and governmental organizations.  I'm not quite sure how Brunet thinks the EU Commission can or should have a say as ESA (IIRC) comes under the Council of Ministers of the EU member countries.

The problem from REL's PoV is how to get more buy in from the European aerospace sector IE Airbus, thus making a better case for something like the European Investment Bank to become involved.  :( Like wise it would be interesting to see what investment the UK government could make without exceeding the EU national subsidy rules (Yes the UKG investment was looked at by the EU. An interesting question would be how much bigger it could have been before it was felt to be introducing "market distortion.")

I still find it ironic that one of the  biggest winners for a full scale Skylon project would be the French, who will supply the skin material, a fact the French government seems completely unaware of.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/14/2016 08:47 am
2] apart from carrier landings, which only happen in Bond movies
And that's where your comprehension fails.   :(
A carrier landing of a Skylon is a plot device for a Bond movie. An X47b is 11m long. A Skylon is 82m. You'd probably need to use a couple of bulk ore carriers as pontoons for the deck.

IRL I expect the USN will face increasing pressure to start basing UAV's on carriers as they can no longer claim UAV's can't do carrier landings.

All posters are responsible for what they post. None are responsible for what readers read.
Quote
Despite the bizarre tangents, everyone seems to agree the pilotless aspect of Skylon is not a big deal.
True.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 01/14/2016 11:26 am


In particular

EU <> EU Parliament <>EU Commission <> ESA <> CNES <> Arianspace.

They are all distinct industrial and governmental organizations.  I'm not quite sure how Brunet thinks the EU Commission can or should have a say as ESA (IIRC) comes under the Council of Ministers of the EU member countries.




well, rather: EU>> EU Parliament, Commission, Council of the EU (ministers), European Council
ESA: Council of ministers of ESA members (not EU members)

The rationale for EU to mess with ESA is precisely that, as they are their main customer, they now want to have a say.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Asteroza on 01/14/2016 11:52 pm
Floating runway...


I wonder if the cost of the runway/spaceport might be mitigated if it were a MegaFloat style linked barge runway in a suitable harbor or lagoon area. Runway construction would then be simply serial production of barge segements and towing to a perpared mooring area. The barges themselves could be made of hollow concrete (simple compartments and/or cellular glass spheres in the aggregate like a syntactic foam) to increase their lifetimes in a marine environment. This would basically mean any island, reef lagoon, or eastward facing coastal harbor could become a skylon spaceport (and by extension gain a local cargo airport).

The japanese MegaFloat floating runway demo used steel barges with link spans, and there are noises the japanese government will fund a new MegaFloat demo for an offshore helicopter base to service offshore oil rigs (to increase helicopter range). Concrete ships/barges were made in WWII, and sometimes manufactured now for floating houses as their base, and now can utilize basalt fiber rather than steel rebar to improve corrosion resistance. US Navy studied the MOB (mobile offshore base) design, which was typically a set of three to five semisubmersible rigs linked together to make a megacarrier. There is an interesting design called the pressure stabilized platform (PSP) that use bottom open hollow cylinders as the base block of a platform barge, which was seriously proposed for use in a replacement for San Diego airport as an offshore airport and as an offshore cargo inspection/transshipment facility for DHS.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 01/15/2016 03:38 am
Not sure why the thread has gone this far astray, but... when in Rome...

Floating runway...
I wonder if the cost of the runway/spaceport might be mitigated if it were a [...] japanese MegaFloat floating runway [] used steel barges with link spans

If we're going to these extremes, why not go whole hog and use an Ekranoplan aircraft carrier?

(https://s-media-cache-ak0.pinimg.com/736x/f0/95/bb/f095bb4f3d6b2d0f5f08d54c7bd70bb2.jpg) (http://"https://s-media-cache-ak0.pinimg.com/736x/f0/95/bb/f095bb4f3d6b2d0f5f08d54c7bd70bb2.jpg")

The approach speed can be high subsonic, rather than the typical slower runway speed. That might make the design a little easier.

The Skylon can land short/long, too fast, too slow, because the "runway" stays under it regardless, with effectively unlimited "run out". The Skylon auto-pilot just needs to hit the top of the approach box (to rendezvous with the carrier), and then focus on staying on heading as it descends; the carrier will adjust to always remain underneath. Take-off obviously works the same, high take-off speed, unlimited "runway"; with the bonus that the fuel to get up to high-subsonic is provided by the carrier.

And once the Skylon has landed, the carrier itself can land in the water and then cruise into dock at any suitable harbour. Or even just meet up with a supply ship and have a new payload (and fuel) loaded onto the Skylon right there for immediate relaunch. (The carrier can also be used as a transport vehicle, moving your takeoff site to anywhere in the world.)

The carrier in the image has a pseudo runway, but since touchdown occurs with zero relative velocity, there's no reason not to use skids or footpads, which tend to be much lighter than full wheeled landing gear. Possibly even use a cradle on the carrier and eliminate the landing gear entirely. (The missile batteries are probably also unnecessary. Probably.)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Lampyridae on 01/15/2016 06:06 am
Not sure why the thread has gone this far astray, but... when in Rome...

Floating runway...
I wonder if the cost of the runway/spaceport might be mitigated if it were a [...] japanese MegaFloat floating runway [] used steel barges with link spans

If we're going to these extremes, why not go whole hog and use an Ekranoplan aircraft carrier?

(https://s-media-cache-ak0.pinimg.com/736x/f0/95/bb/f095bb4f3d6b2d0f5f08d54c7bd70bb2.jpg) (http://"https://s-media-cache-ak0.pinimg.com/736x/f0/95/bb/f095bb4f3d6b2d0f5f08d54c7bd70bb2.jpg")

The approach speed can be high subsonic, rather than the typical slower runway speed. That might make the design a little easier.

The Skylon can land short/long, too fast, too slow, because the "runway" stays under it regardless, with effectively unlimited "run out". The Skylon auto-pilot just needs to hit the top of the approach box (to rendezvous with the carrier), and then focus on staying on heading as it descends; the carrier will adjust to always remain underneath. Take-off obviously works the same, high take-off speed, unlimited "runway"; with the bonus that the fuel to get up to high-subsonic is provided by the carrier.

And once the Skylon has landed, the carrier itself can land in the water and then cruise into dock at any suitable harbour. Or even just meet up with a supply ship and have a new payload (and fuel) loaded onto the Skylon right there for immediate relaunch. (The carrier can also be used as a transport vehicle, moving your takeoff site to anywhere in the world.)

The carrier in the image has a pseudo runway, but since touchdown occurs with zero relative velocity, there's no reason not to use skids or footpads, which tend to be much lighter than full wheeled landing gear. Possibly even use a cradle on the carrier and eliminate the landing gear entirely. (The missile batteries are probably also unnecessary. Probably.)

All good Bond movies end with rapid unplanned disassembly... I can see this happening :)

I wonder what Musk will call it. The SHS It's Just Part Of The Software Development Process?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 01/15/2016 06:41 am
An article about TISICS whose job it will be to make the titanium composite struts (thanks to Jamie Rowland for sending me this link).

http://www.geektime.com/2016/01/14/this-uk-startup-is-building-a-new-kind-of-space-age-metal/
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/15/2016 09:07 am
Floating runway...

To be clear.

My point was that that a Skylon takeoff or landing on a floating runway is a plot device for an action thriller.

IRL it's a stupid idea that adds enormous amounts of complexity and risk to a system that has enough risk to go around already.  :(

However  for more normal sized aircraft and UAVs (EG the F35 or X47b, or European, Russian, Chinese or Indian equivalents) I believe automated carrier landings will become routine within the next 10 years.

IIRC bad carrier landings and takeoffs generate significant numbers of repairs that take those vehicles off the flight line for fairly long periods.  Modern aerial vehicles are basically FBW or FBL and getting more expensive.  The pragmatic solution is add (possibly) a few sensors and a new software module (all these vehicles are designed to support S/W upgrades anyway) to handle this.

I do like wing-in-ground-effect vehicles and the old "Caspian Sea Monster" has to be the Daddy of these (another piece of tech suitable for a Bond villain. I wonder if anyone of the still exists, and if so can they still fly?) but definitely OT.  I will note the core problem of them seemed to be the huge fuel load it burned getting to cruising conditions, IIRC due to the huge thrust needed to start it moving.

Fix that and I think you have quite an attractive high mass, high volume, high(ish) speed freight vehicle that is not stopped by any obstacle less than about 200m high, but that won't be easy.  :(

Sadly while an Ekranoplane might make a "moving landing strip" for a Skylon it won't allow replacing the landing gear with pads. A rolling takeoff is a key part of Skylon ConOps and REL have done a lot ow work to confirm a landing gear mass of 1.5% of Gross Landing Weight (the usual for large commercial aircraft is about 4% but the B58 did 1.5%) is viable.

While definitely an "Advance Concept" this is OT for this thread.
 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/15/2016 11:11 am
An article about TISICS whose job it will be to make the titanium composite struts (thanks to Jamie Rowland for sending me this link).

http://www.geektime.com/2016/01/14/this-uk-startup-is-building-a-new-kind-of-space-age-metal/
I've read the article. It doesn't really add much to what we know of them, although being an MBO fo Quintiq is interesting.

Unlike a lot  of companies in this area they seem to have ambitions of moving "downstream" into the mfg of the parts as well, which is going to be needed.

I hope they continue to prosper.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Ravenger on 01/17/2016 08:55 pm
I found this old article from 2008 that that's got a very high-resolution cut-way CAD rendering of the sabre engine which I've not seen before. This was used to produce the 1/6th scale model for use at airshows, etc.

http://www.engineeringcapacity.com/news101/business-news/it_is_rocket_science_from_gemini

I think this makes the layout much clearer than other cut-aways I've seen.

It's new to me, so apologies if it's been posted before in the many previous Skylon threads.


Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 01/17/2016 09:13 pm
Can anyone discern any thirst vector control hardware for those nozzles? To the untrained eye they appear locked in place by the structure.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: NovaSilisko on 01/17/2016 09:49 pm
I'll attach it here, just in case that article ever blows up for whatever reason.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Soundbite on 01/18/2016 10:48 am
I have just come across an interesting report by Purdue University, published in July 2015, to study a design of a SABRE cycle based engine that is capable of powering a modified X-43 at Mach 5, so that they can test the performance of a modified X-43 when cruising at Mach 5 as well as the performance of the pre-cooler, see http://www.slideshare.net/JulianWang2/aae537sabrefinalreportdocx (http://www.slideshare.net/JulianWang2/aae537sabrefinalreportdocx).

Just note that it takes a few seconds for all the tables and images to load.

What do you all think?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 01/18/2016 03:21 pm
It has been stated in a couple of places that the axisymmetric inlet on the SABRE/Skylon - ingesting mostly uninterrupted free stream air - simplifies its design, so fitting SABRE to a rectangular inlet behind a forebody will involve some work. Mind you, if it only has to work at M5 (and not M0-M5 as on Skylon) perhaps thats doable.

X-43 is expendable, so somebody's going need a healthy budget to make this happen...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 01/18/2016 03:53 pm
Orbitec (now owned by SNC, of Dream Chaser fame) has received a NASA grant that amongst many other things looks at rocket-based combined cycle engines. And one of their partners is Purdue...

http://orbitec.com/documents/ORBITEC_RTAPS_2_contract_announce_pr_12.8.2015.pdf
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 01/19/2016 10:50 pm
Here's a SABRE brain teaser: will flying through heavy rain and/or ingesting spray kicked up from the nose gear be any cause for concern?

In a generic turbojet the compressor blades have to deal with rain drops, but by the time you get to the back, high pressure stages I think the water has evaporated so you just pass humid air to the combustion chamber. But in Skylon the rain/water has to pass in-between the precooler tubes before it hits the compressor. Looking at that exploded diagram it's hard to tell what will happen. Will most of the rain (relatively dense) fly past the pre cooler into the bypass ducts? Or does it get sucked through the precooler? And if the operating pressures are high enough ahead of the compressor then perhaps it just evaporates before it's of any concern?

This is the sort of thing they could test with their current precooler setup - if it wasn't too risky.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 01/20/2016 12:56 am
Didn't they already test this?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 01/20/2016 01:14 am
They certainly tested humid air - as demonstrating frost control was a key goal. But I'm not sure if that was just ambient humidity, or if they went on to chuck actual raindrops/spray in the front end.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 01/20/2016 08:24 am
Here's a SABRE brain teaser: will flying through heavy rain and/or ingesting spray kicked up from the nose gear be any cause for concern?

In a generic turbojet the compressor blades have to deal with rain drops, but by the time you get to the back, high pressure stages I think the water has evaporated so you just pass humid air to the combustion chamber. But in Skylon the rain/water has to pass in-between the precooler tubes before it hits the compressor. Looking at that exploded diagram it's hard to tell what will happen. Will most of the rain (relatively dense) fly past the pre cooler into the bypass ducts? Or does it get sucked through the precooler? And if the operating pressures are high enough ahead of the compressor then perhaps it just evaporates before it's of any concern?

This is the sort of thing they could test with their current precooler setup - if it wasn't too risky.

I remember this answered by Alan Bond at one of the talks I attended (apologies I can't remember which) when the apparent fragility of the pre-cooler was questioned. He stated first that the HX is much stronger than it looks when pressurised, but (more importantly) the airflow makes a sharp 90deg turn to enter the HX whereas debris (and liquid? - not sure if this was mentioned specifically) would continue past to the RAMjets.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 01/20/2016 06:06 pm
Thanks for that. What I find interesting is how unaerodynamic the precooler looks to the untrained eye. At low speeds (say take off speed of 0.5M) it appears as though debris and rain will hit the front edge of the third and fourth precooler ring head on. (While some will fly past towards the bypass burner inlets.)

My guess is it's incorrect to imagine rain drops flying into the precooler/bypass at high Mach because by then the temperatures and pressures inside the engine will vaporize them in short order.

I'm not sure if air is intended to be drawn into the side of the precooler rings that face the airstream, if not then you could easily imagine ramps added designed to deflect light debris/spray away from the rings, and out the bypass ducts.

Please don't think I'm suggesting REL haven't considered this - just curious about how it's all supposed to work.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Lars-J on 01/21/2016 05:33 am
Can anyone discern any thirst vector control hardware for those nozzles? To the untrained eye they appear locked in place by the structure.

I'll attach it here, just in case that article ever blows up for whatever reason.

Yes, that is a good question. There must be some thrust vector control/gimbal ability, otherwise there is no engine out capability and *very limited* control authority outside the atmosphere. The only way I can see it is if the entire "purple plate" that holds the four engine chambers gimbals, but that does seem very complex.

I certainly look forward to seeing a an actual working SABRE engine, that would go a *long* way towards making me a Skylon believer. But this design image must be hiding or obfuscating quite a few details, because as-is it seems more like a "rube goldberg machine" than a practical engine.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 01/25/2016 04:22 pm
Just noticed Alan Bond does not appear on the Reaction Engines web site board of directors or their executive
leadership team.

Anyone know anything about this ?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 01/25/2016 04:38 pm
are people going to carry on accepting the necessity of falling COPVs?
The COPV for the F9 stage was inside the tank most of the time.
I was thinking of the hairy black space balls that farmers come across from time to time

Those are not launch vehicle specific.  They are in spacecraft too and no different than other space hardware that returns.  Reusable launch vehicle are not going to change this
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 01/25/2016 04:39 pm

No boil off means no burn off.


No such thing with hydrogen.  There is always boil off.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/25/2016 06:58 pm

No boil off means no burn off.


No such thing with hydrogen.  There is always boil off.
AFAIK all LH2 work has been done at NBP.  I'm also not sure how these systems are pre cooled, or wheather they have just flushed the system and let it flash boil to GH2 before venting.

I think this has a lot to do with design decisions made in the 1960's. IIRC the SLS LH2 delivery system will cut the H2 waste by 50%.

My instinct is the key issues are a)Precooling all the hardware down to be the precooled level b)Precooling the LH2.

REL plan to operate around 16-18K, rather than 20K+

what has been done is not the limit of what can be done.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 01/25/2016 07:16 pm

No boil off means no burn off.


No such thing with hydrogen.  There is always boil off.
AFAIK all LH2 work has been done at NBP.  I'm also not sure how these systems are pre cooled, or wheather they have just flushed the system and let it flash boil to GH2 before venting.

I think this has a lot to do with design decisions made in the 1960's. IIRC the SLS LH2 delivery system will cut the H2 waste by 50%.

My instinct is the key issues are a)Precooling all the hardware down to be the precooled level b)Precooling the LH2.

REL plan to operate around 16-18K, rather than 20K+

what has been done is not the limit of what can be done.

I think Jim's point was that "boil-off" isn't something you can prevent due to the nature of LH2. Doesn't matter what temps REL is planning on working with as long as it's lower than ambient the propellant WILL boil, the question is at what rate. REL "planning" on having zero-boil off is part of the reason folks don't accept they fully understand what they are talking about :)

Hint: 16-18K simply means you have from there to 20K before boil off becomes serious, and you "vent" in fact to help keep the propellant cool :)

I'll admit that line struck me as odd as well:
"However REL's COP is to load and launch within 2 hrs or recycle the propellants to long term storage. By pre cooling the hardware and the propellants they expect zero boiloff under normal operation."

Load and launch in two hours is pretty strict timing and by "pre-cooling" the hardware they are in essence planning on flowing large amounts of LH2 THROUGH the system and a large percentage of it is going to be fully gaseous and either need to be recycled or dumped until the system is fully cooled and even THEN the on-board LH2 is going to be trying to boil unless they are constantly cycling propellant through the tanks. (And all that piping is NOT going to be as insulated as the tanks are btw)

Simply put, until REL shows a zero-boil off storage tank made of flight-weight materials and shows no "boiling" for two full hours no one who has worked with LH2 on a consistent basis is going to take the assumption seriously.

I for one have noted that REL seems to be confusing/conflating "pre-cool" with "sub-cool" of the LH2 which btw runs into "slush-hydrogen" operations which seems to be what they are talking about rather than "pre-cooling".

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 01/25/2016 09:33 pm

I think Jim's point was that "boil-off" isn't something you can prevent due to the nature of LH2. Doesn't matter what temps REL is planning on working with as long as it's lower than ambient the propellant WILL boil, the question is at what rate. REL "planning" on having zero-boil off is part of the reason folks don't accept they fully understand what they are talking about :)
Wikipedia tells me Hydrogen won't boil off below 20K. But the manual doesn't claim zero boil off, it only has zero venting (minimising boil off would help with that)

That's the confusing part for most folks as venting is required unless there's no boil off and hence no need for venting :)

The problem is that LH2 still heats up to ambient and wants to boil off. The only way to prevent this is to keep the LH2 colder than 20K and THAT isn't easy or cheap. (And mind you, this does not address the fact that LH2 LEAKS even if when liquid, it slips right out of ANY closed system and that's something no one has every managed to prevent)

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I'll admit that line struck me as odd as well:
"However REL's COP is to load and launch within 2 hrs or recycle the propellants to long term storage. By pre cooling the hardware and the propellants they expect zero boiloff under normal operation."

Load and launch in two hours is pretty strict timing
Fuel loading is 40 minutes, followed by 24 minutes of towing and final checks, followed by a hold time of up to two hours, during which time the temperature rises in the foam insulated tanks inside a nitrogen purged atmosphere inside layers of Mylar, inside the ceramic shell. If the temperature gets above 20K, then the pressure in the tank will start to rise - I don't know if that's accounted for in the concept design, but these people have spent decades working with the thermodynamic properties of hydrogen If it's not gone in that time it needs to be towed back

Uhm, yes and while they have spent decades working with the "thermodynamic properties" of hydrogen they are far from the only ones :) And yes they are planning on what amounts to a series of super-insulated "shells" to hinder the boil off of the LH2, but the fact they are counting on "zero-boil-off" after having spent "decades" working with the thermodynamic properties of hydrogen is something others who have been working for decades with the thermodynamic properties of hydrogen question since having no vents means you can't relieve the pressure build up in the tanks if you DO run into problems.

On the other hand let me add that there ARE in fact 'vents' in the design in that they can "vent" through the engines themselves but REL isn't planning it seems to follow any of the normal procedures for working with quantities of liquid hydrogen which is why there are questions from those who have also "yadda-yadda-decades-working-hydrogen" that don't seem to be addressed.

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and by "pre-cooling" the hardware they are in essence planning on flowing large amounts of LH2 THROUGH the system and a large percentage of it is going to be fully gaseous and either need to be recycled or dumped until the system is fully cooled and even THEN the on-board LH2 is going to be trying to boil unless they are constantly cycling propellant through the tanks. (And all that piping is NOT going to be as insulated as the tanks are btw)
* Install pipes and run LN2 through
* Connect to liquid Helium source and fill to cool.  Drain and recover helium
* Connect LH2 and LO2 pipes and fill.  Fill to 95% then top off

I'm assuming "Draw vacuum in filler tube [...] Tank chill down (H2 boils off until tank is cold)" refers to the storage tank where they sub-cool the hydrogen, otherwise cooling Skylon with helium seems like an unneeded step.

Liquid helium would be the only substance COLDER than LH2 so if they cool to Liquid Helium temperatures but that's a lot of helium to be running through the system and then recycling. And it still only delays the boil off. Enough to meet their ops deadline? Maybe, that's what REL thinks but others don't see it that way.

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Simply put, until REL shows a zero-boil off storage tank made of flight-weight materials and shows no "boiling" for two full hours no one who has worked with LH2 on a consistent basis is going to take the assumption seriously.
It's conceptual operations of a conceptual vehicle. If a top-up and vent hose had to be used, no one would have batted an eyelid - but these people who have spent decades working with the thermodynamic properties of hydrogen seem to think it wont be needed - if it turns out they're wrong they have egg on their face, ConOps needs revising, infrastructure costs go up, and some mass margin is lost - but the vehicle concept probably remains valid.
I guess that's a step along from no-one taking the idea seriously because intake air would be too hot, or no-one taking the idea seriously because precoolers are too slow, or no-one taking the idea seriously because precoolers are too heavy, or no one taking the idea seriously because undercarriage would be too heavy.

That's actually part of the problem as a whole, it IS a "conceptual" operations suggested for a "conceptual" vehicle and it's the fact that with all their experience working with the thermodynamic of hydrogen they are suggesting none of the proven and trusted technological solutions from "decades of practical work with the thermodynamics of hydrogen" are applicable to their concept :) Specifically it's "our design is so different" that has people worrying over their design as if it's that different it should be "provable" with a working prototype. They did it with the heat exchangers did they not?

Given that the outcome of an unvented tank with "boiling" cryogenic fluid in it is a bomb waiting to go off it's not unreasonable to want to see a working example before you commit to accepting the statement.

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I for one have noted that REL seems to be confusing/conflating "pre-cool" with "sub-cool" of the LH2 which btw runs into "slush-hydrogen" operations which seems to be what they are talking about rather than "pre-cooling".
REL or commentators?
My understanding is they precool Skylon, before filling it with sub-cooled hydrogen, where sub-cooled means significantly below the boiling point of hydrogen, but above freezing.

"Below the boiling point but above freezing" is in fact the usual definition of "slush" hydrogen used in most cases hence my question.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/25/2016 11:41 pm
"Below the boiling point but above freezing" is in fact the usual definition of "slush" hydrogen used in most cases hence my question.
That is a very suspicious definition.  :(

"Slush" Hydrogen is a very specific term for a 2 phase mix of liquid and solid Hydrogen, IE Hydrogen below the melting point of Hydrogen. IE c14K. IOW like a slush puppy desert.

"Sub cooled" Hydrogen would be LH2 cooled below it's normal (IE 1 atm pressure) boiling point, but remaining single phase.
A system "pre cooled" would be a system flushed with a cold fluid to bring the system down to the LH2 storage temperature. If the system is sealed then while it's quite high volume the fluid can be recovered and re-circulated.
Obviously GHe is the choice for this fluid but making it possible for a re-circulation path to cool the whole of the system is a design issue, not exactly cutting edge thermodynamics.

Of course it will take good HX design to cool the He, but since that's REL's core skillset I think that won't be a problem.

Please note Skylon propellant tanks are designed to be suspended from low themal conductivity and fixed at one end, so they can grow and contract with minimal structural resistance, and minimal heat leaks into the tanks.

Anyone who wants to know the scale of the problems shoudl figure what it takes to lower several tonnes of Aluminum alloy (or several tonnes of inconel, to represent the engines) to the necessary temperature, and once there how fast it would heat up.

BTW NASA have done a number of studies on Zero Boiloff Tankage.

IIRC the key issue was ensuring the inlet spray bars remained submerged to avoid either +ve or -ve pressure spiked (IE tank collapses).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/26/2016 08:24 pm
I thought it referred to hydrogen at it's triple-point of 14.01 K
Indeed.

Randy has pointed out US aerospace R&D seems to have gone off the rails somewhere in the 60's when they became obsessed with SCRamjets.

My feeling is the same applies to their pursuit of "Slush" Hydrogen. It's that same sense of "performance Uber Alles" of pursuing the absolute best performance (in this case in terms of density) regardless of the practical problems, when more viable options, which are simpler to implement, exist.

This is a side point. AIUI the stated concern is that people doubt a Skylon could stay on the runway for 2 hrs without venting.

I agree that a system that carries out the chill down LH2 sub cooling will need to vent gas to the atmosphere and that will be burnt off.

The question is with all that pre cooled hardware filled with sub cooled propellant resist the heat coming in from the environment long enough to eliminate venting?

I'll note a few points.

Jim pointed out that a layer of paint alone was sufficient to reduce LOX boil off to very  low levels.

Alan Bond noted that LH2 has a SHC 4xs that of water (already excellent, given most chemicals with its molecular weight are either gases or low BP liquids).

Those extra degrees of sub cooling give a large cushion (coupled with the heat the hardware would have to absorb before it gets to the propellant. Call it 2GJ before LH2's heat of vaporization would be needed to vaporize and the pressure rise, excluding similar benefits due to sub cooling LOX.

Leaving cryogenic tanks sealed indefinitely without active cooling would clearly be very difficult but that is simply not the case here.  The time frame is very tightly limited. With enough thermal mass it sounds very unlikely to me that a 2 hr hold on runway would not be possible.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 01/27/2016 01:33 pm

Jim pointed out that a layer of paint alone was sufficient to reduce LOX boil off to very  low levels.


Didn't say anything about the boil off.  Just that LOX tanks only have paint and no insulation.  LOX is boiling off and is replenished up to a few minutes before launch.  The open vents are closed but the boil off still causes the vent to open occasionally.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 01/27/2016 04:16 pm
I thought it referred to hydrogen at it's triple-point of 14.01 K
Indeed.

Like many other "grey" areas where people writing the papers don't want to get to specific, "slush hydrogen" tends to be generally described rather than nailed to a specific parameter. My point was simply that it's described as "below-but-above" in a lot of the papers I've read which struck me as odd.

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Randy has pointed out US aerospace R&D seems to have gone off the rails somewhere in the 60's when they became obsessed with SCRamjets.

LACE, now don't forget LACE as well :)

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My feeling is the same applies to their pursuit of "Slush" Hydrogen. It's that same sense of "performance Uber Alles" of pursuing the absolute best performance (in this case in terms of density) regardless of the practical problems, when more viable options, which are simpler to implement, exist.

Actually in most cases it's invoked for the simple reason of trying to reduce the tankage size of an LH2 system. In rarer cases it's used to allow "recycling" of gaseous LH2 into at least a semi-liquid state by running it back through the 'slush' after its used for some cooling purpose. From what I've read it usually isn't worth doing unless there is a very compelling reason, on the gripping-hand though there usually IS a very compelling reason which is why it gets invoked :)

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This is a side point. AIUI the stated concern is that people doubt a Skylon could stay on the runway for 2 hrs without venting.

Actually Jim brought up that LH2 "boils-off" and I 'tried-to-help' and failed miserably :)
http://forum.nasaspaceflight.com/index.php?topic=36826.msg1482971#msg1482971

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I agree that a system that carries out the chill down LH2 sub cooling will need to vent gas to the atmosphere and that will be burnt off.

The question is with all that pre cooled hardware filled with sub cooled propellant resist the heat coming in from the environment long enough to eliminate venting?

"MY" main point was the question of why NOT vents? (Thanks for the calc's JCRM :) )

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/27/2016 07:12 pm
LACE, now don't forget LACE as well :)
Indeed. LACE is the "performance Uber Alles" approach.  SABRE is the "good enough to get the job done" approach.  :)
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Actually in most cases it's invoked for the simple reason of trying to reduce the tankage size of an LH2 system. In rarer cases it's used to allow "recycling" of gaseous LH2 into at least a semi-liquid state by running it back through the 'slush' after its used for some cooling purpose. From what I've read it usually isn't worth doing unless there is a very compelling reason, on the gripping-hand though there usually IS a very compelling reason which is why it gets invoked :)
I don't know about the 60's concepts (IIRC some of Bono's SSTO ideas had it in the small print, along with Beryllium alloy structures) but I get the feeling a lot of the time it comes in when someone has mis-estimated the performance (either engine or structural) of their planned design. 

It's from the same place that caused HOTOL to develop a jet engined takeoff trolley. 

A valuable lesson that (I think) the REL team took to heart.
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"MY" main point was the question of why NOT vents? (Thanks for the calc's JCRM :) )
Well there's the practical and the philosophical.

Skylon is moved after propellant load to its start point on the runway.  Yes you could run some kind of flexible vent pipe to a burn off stack but imagine how clumsy that would be  :(

Option b would be to stick vent system on the vehicle.  H2 is very light and would disperse very quickly but I'm not sure that would be enough to convince the CAA it would not need some kind of burn off system.

Then there's the philosophical point. IE the COP.

Aircraft don't have flare stacks for fuel vapors from their tanks.  VTO  ELV's do.

AFAIK the nearest they get are Nitrogen generators, to purge fuel tanks on large aircraft of explosive vapors, are quite a recent feature (although IIRC SOP for military aircraft)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/27/2016 07:12 pm
Didn't say anything about the boil off.  Just that LOX tanks only have paint and no insulation.  LOX is boiling off and is replenished up to a few minutes before launch.  The open vents are closed but the boil off still causes the vent to open occasionally.
Noted.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 01/27/2016 07:50 pm
LACE, now don't forget LACE as well :)
Indeed. LACE is the "performance Uber Alles" approach.  SABRE is the "good enough to get the job done" approach.  :)

I'm not so sure it's actually "performance-et-al" really because it's quite clear the people working on the "problems" were in many ways going out of their way to "work" the problems even when there was evidence (but none they were paying attention to) of a "simpler" way to do things. Maybe more the allure of the "perfect" system approach, with eyes fixed firmly on the "prize" with all the blinders that implies :)

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Actually in most cases it's invoked for the simple reason of trying to reduce the tankage size of an LH2 system. In rarer cases it's used to allow "recycling" of gaseous LH2 into at least a semi-liquid state by running it back through the 'slush' after its used for some cooling purpose. From what I've read it usually isn't worth doing unless there is a very compelling reason, on the gripping-hand though there usually IS a very compelling reason which is why it gets invoked :)
I don't know about the 60's concepts (IIRC some of Bono's SSTO ideas had it in the small print, along with Beryllium alloy structures) but I get the feeling a lot of the time it comes in when someone has mis-estimated the performance (either engine or structural) of their planned design. 

It's from the same place that caused HOTOL to develop a jet engined takeoff trolley.

Actually I was thinking of Bono's case specifically and the fact it had to "fit" into what was supposed to be a "basic" S-IVB stage :) There simply wasn't room to fit the needed amount of LH2 in any form BUT slush... 

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"MY" main point was the question of why NOT vents? (Thanks for the calc's JCRM :) )
Well there's the practical and the philosophical.

Skylon is moved after propellant load to its start point on the runway.  Yes you could run some kind of flexible vent pipe to a burn off stack but imagine how clumsy that would be  :(

Option b would be to stick vent system on the vehicle.  H2 is very light and would disperse very quickly but I'm not sure that would be enough to convince the CAA it would not need some kind of burn off system.

Then there's the philosophical point. IE the COP.

Aircraft don't have flare stacks for fuel vapors from their tanks.  VTO  ELV's do.

AFAIK the nearest they get are Nitrogen generators, to purge fuel tanks on large aircraft of explosive vapors, are quite a recent feature (although IIRC SOP for military aircraft)

I'd actually rather face the truth you're working with hydrogen and face the issues :)

In either case though it still doesn't make that much sense as these "issues" were faced when there was consideration of using LH2 to power aircraft, but I suspect the main issue is the amount of LH2 involved and the more advanced knowledge of dealing with its vapors in an operational manner.

The reading is confusing as for the most part most VTO and all HTO designs using LH2 don't seem to be concerned with LH2 venting and/or leakage in operations. Yet VTO rocket operations on a pad it's an assumed requirement.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Asteroza on 01/28/2016 12:55 am
Hrm, if one were committed to flaring off somehow, how about a hobby/micro gas turbine with a shaft motor/generator to regulate the RPM'S? Keep the compressor turning hard enough to heat air to autoignite any vented hydrogen gas flushed into the combustor. Piping to the rear near the SOMA engines, plus maybe five kilos worth of gear?

Vehicle self-flaring would avoid hydrogen umbilicals after tanking...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/28/2016 08:32 am
It would be about 30 tonnes of hydrogen that would need to be evaporated to chill (my estimate of) 180 tonnes of fuel. That's a lot to burn, even if one was happy to just throw it away. On the other hand, it's a lot to pressurise and store - so  who knows what actual operational procedure would be.
The usual figures for Skylon are it holds about 150 tonnes of LO2 and about 60 tonnes of LH2.

John Whitehad's team estimated LV propellant tanks are about 1% of contents weight except for LH2, when (IIRC) it's nearer 12% (Shuttle ET H2 is about 1/8 mass of LH2 it holds).
That's about 9 tonnes of Aluminium to cool down. With engines being roughly 24 tonnes of superalloy.

Assuming the drain and fill pipes are well located it should be possible to re-circulate Helium through the whole system to give good coverage of all the pipes and tanks. 

Note that LN2 is the cheapest bulk cryogen (described as being cheaper than "A quart of milk" in tanker car quantities) and with a delta t of 2deg (demonstrated by the X33 sub cooler HX) that would get the whole structure (and contents) to 79K (quite how SX get their LO2 tank to 65K remains something of a mystery to me).

Beyond that you'd need to run LH2 to cool the GHe further. Sub cooling LH2 either takes lots of LHe or sub atmospheric boiling of some of the LH2 to cool the rest. This was how the the X33 programme did it.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: hkultala on 01/28/2016 01:40 pm
It would be about 30 tonnes of hydrogen that would need to be evaporated to chill (my estimate of) 180 tonnes of fuel. That's a lot to burn, even if one was happy to just throw it away. On the other hand, it's a lot to pressurise and store - so  who knows what actual operational procedure would be.
The usual figures for Skylon are it holds about 150 tonnes of LO2 and about 60 tonnes of LH2.

John Whitehad's team estimated LV propellant tanks are about 1% of contents weight except for LH2, when (IIRC) it's nearer 12% (Shuttle ET H2 is about 1/8 mass of LH2 it holds).
That's about 9 tonnes of Aluminium to cool down. With engines being roughly 24 tonnes of superalloy.

The shuttle tank also contains 630 tonnes of O2, the 26 tonne total weight the total weight of the O2+H2 tanks.

So your 12% number is total rubbish.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 01/28/2016 02:30 pm

The shuttle tank also contains 630 tonnes of O2, the 26 tonne total weight the total weight of the O2+H2 tanks.

So your 12% number is total rubbish.

Wikipedia gives the (SLWT) dry ET mass as 26.5T
1% of the LO2 mass would be 6.3T
12% of the 106T LH2 mass would be 12.7T (1/8th would be 13.3T)
This leaves 6.9 - 7.5T for the intertank and other miscellaneous

Given the limited info, 12% seems plausible to me - and certainly doesn't deserve to be called "total rubbish".
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Asteroza on 01/28/2016 10:19 pm
Would an engineered aluminum material be worth the weight/expense to avoid the thermal conductivity? Say a 3D printed tank wall that was actually two aluminum face sheets and cubic octet truss honeycomb?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: AnalogMan on 01/28/2016 10:45 pm

The shuttle tank also contains 630 tonnes of O2, the 26 tonne total weight the total weight of the O2+H2 tanks.

So your 12% number is total rubbish.

Wikipedia gives the (SLWT) dry ET mass as 26.5T
1% of the LO2 mass would be 6.3T
12% of the 106T LH2 mass would be 12.7T (1/8th would be 13.3T)
This leaves 6.9 - 7.5T for the intertank and other miscellaneous

Given the limited info, 12% seems plausible to me - and certainly doesn't deserve to be called "total rubbish".
12% seems to be stated a little too precise given the way it was estimated. No need, however for the LWT:
Quote from: http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/et.html
Liquid Hydrogen Maximum 227,641 pounds
[...]
The liquid hydrogen tank is 331 inches in diameter, 1,160 inches long, and has a volume of 53,518 cubic feet and a dry weight of 29,000 pounds
or 12.74%
Now, Skylon's tanks aren't structural, so it may be lighter - but they're less optimally shaped, so it's probably a good estimate.

Disappointingly, the SHC of aluminuim is ridiculous at cryogenic temperatures, with just 0.055 J/g to raise its temperature from 16 to 22 K and its thermal conductivity remains high at 27W/m K - so it wont be doing much to slow the temperature rise,

And this is the description given for the SLWT:

The liquid hydrogen tank is a semi-monocoque structure designed to contain 227,641 pounds of propellant fuel; it measures 1160.75 inches long with on outside skin diameter of 331 inches, has a total volume of 53,518 cubic feet, and its empty weight is approximately 23,600 pounds.

[Taken from "Space Shuttle External Tank - System Definition Handbook SLWT, December 1997"]

So about 10.4% for the lighter version
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 01/29/2016 08:38 am
A ?new? promotional puff:

http://www.msn.com/en-us/video/t/the-new-engine-that-could-revolutionise-aviation/vp-BBoFjko (http://www.msn.com/en-us/video/t/the-new-engine-that-could-revolutionise-aviation/vp-BBoFjko)
"destroy all the other naysayers that say this can;t be done"

This piece implies that BAe's interest is more in LAPCAT/Scimitar - media bias, perhaps?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 01/29/2016 10:07 am
This piece implies that BAe's interest is more in LAPCAT/Scimitar - media bias, perhaps?
Scimitar is a better missile engine? Four hours to Australia is of more interest to the general public than space access? (weird right? but then the general public watch Big Brother and the X Factor)

'Fraid I'm guilty with the X Factor - honestly guv, my wife makes me!
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/29/2016 08:54 pm
A ?new? promotional puff:

http://www.msn.com/en-us/video/t/the-new-engine-that-could-revolutionise-aviation/vp-BBoFjko (http://www.msn.com/en-us/video/t/the-new-engine-that-could-revolutionise-aviation/vp-BBoFjko)
"destroy all the other naysayers that say this can;t be done"

This piece implies that BAe's interest is more in LAPCAT/Scimitar - media bias, perhaps?
The LAPCAT stuff was a fairly small part of the report I thought. LAPCAT remains a very different engine from SABRE.  The joker in the pack remains coping with the prolonged heating on a fuselage during cruise.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 01/29/2016 11:07 pm

A ?new? promotional puff:

http://www.msn.com/en-us/video/t/the-new-engine-that-could-revolutionise-aviation/vp-BBoFjko (http://www.msn.com/en-us/video/t/the-new-engine-that-could-revolutionise-aviation/vp-BBoFjko)
"destroy all the other naysayers that say this can;t be done"

This piece implies that BAe's interest is more in LAPCAT/Scimitar - media bias, perhaps?
The LAPCAT stuff was a fairly small part of the report I thought. LAPCAT remains a very different engine from SABRE.  The joker in the pack remains coping with the prolonged heating on a fuselage during cruise.

I think it's above eight minutes and the skin of the craft tears off.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 01/29/2016 11:57 pm
Make 'er out of Titanium, then...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 01/30/2016 12:00 am

Make 'er out of Titanium, then...

I think even that has its issues at hypersonic speeds as the craft starts to stretch, the old SR-71 used to and that was only doing Mach 3.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 01/30/2016 03:30 pm
A ?new? promotional puff:

http://www.msn.com/en-us/video/t/the-new-engine-that-could-revolutionise-aviation/vp-BBoFjko (http://www.msn.com/en-us/video/t/the-new-engine-that-could-revolutionise-aviation/vp-BBoFjko)
"destroy all the other naysayers that say this can;t be done"

This piece implies that BAe's interest is more in LAPCAT/Scimitar - media bias, perhaps?
The LAPCAT stuff was a fairly small part of the report I thought. LAPCAT remains a very different engine from SABRE.  The joker in the pack remains coping with the prolonged heating on a fuselage during cruise.

I agree; more than 75% of the piece was dedicated to SABRE and reusable space vehicles. However my point was based on the last minute where the video and talk appeared all about LAPCAT, with the quote at 3:51 -

"The project [LAPCAT visuals playing] received a huge boost at the end of 2015: a $100M investment from BAe Systems and the British government" followed shortly after at 4:06 -

Varvill: "When that day happens and that AEROPLANE [my emphasis] rolls out on the tarmac will be a pretty emotional moment..."

Hope I'm wrong...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 01/30/2016 06:59 pm

A ?new? promotional puff:

http://www.msn.com/en-us/video/t/the-new-engine-that-could-revolutionise-aviation/vp-BBoFjko (http://www.msn.com/en-us/video/t/the-new-engine-that-could-revolutionise-aviation/vp-BBoFjko)
"destroy all the other naysayers that say this can;t be done"

This piece implies that BAe's interest is more in LAPCAT/Scimitar - media bias, perhaps?
The LAPCAT stuff was a fairly small part of the report I thought. LAPCAT remains a very different engine from SABRE.  The joker in the pack remains coping with the prolonged heating on a fuselage during cruise.

I agree; more than 75% of the piece was dedicated to SABRE and reusable space vehicles. However my point was based on the last minute where the video and talk appeared all about LAPCAT, with the quote at 3:51 -

"The project [LAPCAT visuals playing] received a huge boost at the end of 2015: a $100M investment from BAe Systems and the British government" followed shortly after at 4:06 -

Varvill: "When that day happens and that AEROPLANE [my emphasis] rolls out on the tarmac will be a pretty emotional moment..."

Hope I'm wrong...

And what's wrong with that?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Stormbringer on 01/31/2016 12:16 am
http://nextbigfuture.com/2016/01/charles-bombardier-has-improved.html

to quote daffy duck when he is about to be in a lot of pain:  "mother"

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/31/2016 05:30 am
And what's wrong with that?
Quite a lot.

The world does not need another weapons system.

It does need a fully reusable launch system that has a real shot at cutting the price of missions 10x.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/31/2016 05:35 am
http://nextbigfuture.com/2016/01/charles-bombardier-has-improved.html

to quote daffy duck when he is about to be in a lot of pain:  "mother"
And this has any relevance to Skylon how?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: NovaSilisko on 01/31/2016 06:57 am
And what's wrong with that?
Quite a lot.

The world does not need another weapons system.

It does need a fully reusable launch system that has a real shot at cutting the price of missions 10x.  :(

I'm confused. Is a Britishism sailing over my head? Isn't aeroplane a general term for aircraft? Or does it mean a military aircraft specifically?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Stormbringer on 01/31/2016 07:20 am
http://nextbigfuture.com/2016/01/charles-bombardier-has-improved.html

to quote daffy duck when he is about to be in a lot of pain:  "mother"
And this has any relevance to Skylon how?
look at the comment section. this could be a competitor to it. though they lack one important thing... a hypersonic engine. Just a minor detail.  :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 01/31/2016 08:28 am

And what's wrong with that?
Quite a lot.

The world does not need another weapons system.

It does need a fully reusable launch system that has a real shot at cutting the price of missions 10x.  :(

I'm confused. Is a Britishism sailing over my head? Isn't aeroplane a general term for aircraft? Or does it mean a military aircraft specifically?

No it is a general term here as well.:)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 01/31/2016 09:32 am
I'm confused. Is a Britishism sailing over my head? Isn't aeroplane a general term for aircraft? Or does it mean a military aircraft specifically?
Yes. It's more BAe systems only making weapon systems. They sold off their commercial airliner business a long time ago.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Archibald on 01/31/2016 09:55 am

Make 'er out of Titanium, then...

I think even that has its issues at hypersonic speeds as the craft starts to stretch, the old SR-71 used to and that was only doing Mach 3.

The SR-71 leaked fuel on the ramp, so much that it had to be refueled after liftoff by a KC-135Q...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 01/31/2016 10:02 am

Make 'er out of Titanium, then...

I think even that has its issues at hypersonic speeds as the craft starts to stretch, the old SR-71 used to and that was only doing Mach 3.

The SR-71 leaked fuel on the ramp, so much that it had to be refuelled after liftoff by a KC-135Q...







How old is SR-71 technology?,I think we have come a long way since then.
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 01/31/2016 02:37 pm

Make 'er out of Titanium, then...

I think even that has its issues at hypersonic speeds as the craft starts to stretch, the old SR-71 used to and that was only doing Mach 3.

The SR-71 leaked fuel on the ramp, so much that it had to be refuelled after liftoff by a KC-135Q...







How old is SR-71 technology?,I think we have come a long way since then.

As far as aircraft are concerned it might be old but it's the only practical example we have going at these kind of speeds. If there was other examples they haven't been disclosed.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hanelyp on 01/31/2016 03:00 pm
The SR-71 leaked fuel on the ramp, so much that it had to be refuelled after liftoff by a KC-135Q...
How old is SR-71 technology?,I think we have come a long way since then.
The SR-71 leaked on the runway because of thermal expansion joints in the fuel tank.  Come up with a fuel tank that can take the heat without thermal expansion joints and you can get a hypersonic aircraft that doesn't leak on the runway.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Rocket Science on 01/31/2016 03:12 pm
The SR-71 leaked fuel on the ramp, so much that it had to be refuelled after liftoff by a KC-135Q...
How old is SR-71 technology?,I think we have come a long way since then.
The SR-71 leaked on the runway because of thermal expansion joints in the fuel tank.  Come up with a fuel tank that can take the heat without thermal expansion joints and you can get a hypersonic aircraft that doesn't leak on the runway.
Nitrile rubber fuel bladder...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 01/31/2016 04:41 pm
The SR-71 leaked on the runway because of thermal expansion joints in the fuel tank.  Come up with a fuel tank that can take the heat without thermal expansion joints and you can get a hypersonic aircraft that doesn't leak on the runway.

So a pressurised liquid hydrogen cryo-tank that can withstand hypersonic shock temperatures for several hours, which is light enough to allow the aircraft to fly, but likely must be strong enough to be a major structural component of the airframe?

...Let me check in the back shed.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 01/31/2016 07:34 pm
And what's wrong with that?
Quite a lot.

The world does not need another weapons system.

It does need a fully reusable launch system that has a real shot at cutting the price of missions 10x.  :(

I'm confused. Is a Britishism sailing over my head? Isn't aeroplane a general term for aircraft? Or does it mean a military aircraft specifically?

More importantly, the term aeroplane generally does not include spaceplane.

My concern is that BAe's interest and money is towards an atmospheric application (such as LAPCAT, or some other military hypersonic) rather than towards reusable space launch, i.e. Skylon.

This is a SPACEFLIGHT forum!
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 01/31/2016 08:09 pm
And what's wrong with that?
Quite a lot.

The world does not need another weapons system.

It does need a fully reusable launch system that has a real shot at cutting the price of missions 10x.  :(

I'm confused. Is a Britishism sailing over my head? Isn't aeroplane a general term for aircraft? Or does it mean a military aircraft specifically?

More importantly, the term aeroplane generally does not include spaceplane.

My concern is that BAe's interest and money is towards an atmospheric application (such as LAPCAT, or some other military hypersonic) rather than towards reusable space launch, i.e. Skylon.

This is a SPACEFLIGHT forum!

Don't be so narrow. Especially if you look suborbital & hypersonic vehicles are covered on here as well. Anyway success with one will probably lead to the other eventually.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 02/01/2016 02:41 pm
I don't think the nomenclature is really a problem, though to repeat my mantra; A Spacecraft is not an Airplane and an Airplane! Space-plane, Aerospaceplane, would be more accurate, but "aero" plane implies an atmosphere only vehicle WHICH I suspect is actually the point since it's BAe and all :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 02/01/2016 06:54 pm

Skylon could not get into space without an atmosphere, it relies upon lifting flight and aerodynamics for control, almost up to MECO



No, the aerodynamic control is not used after a few minutes and certainly not near MECO.  The engines provide most of the control
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 02/01/2016 07:55 pm
Yes,  it is. See page 11 of Skylon Aerodynamics and SABRE Plumes (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150015818.pdf) report, which details the foreplane activity up to 75KM.


No, Mach 17 is not near MECO and 75km is far from orbital altitude.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 02/01/2016 11:19 pm

I used the NASA source as you're less likely to dismiss it as biased.


It isn't a source.  It is an in depended study that makes assumptions on the flight profile.  It doesn't use an official Skylon trajectory
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 02/03/2016 01:08 pm
The SR-71 leaked on the runway because of thermal expansion joints in the fuel tank.  Come up with a fuel tank that can take the heat without thermal expansion joints and you can get a hypersonic aircraft that doesn't leak on the runway.

So a pressurised liquid hydrogen cryo-tank that can withstand hypersonic shock temperatures for several hours, which is light enough to allow the aircraft to fly, but likely must be strong enough to be a major structural component of the airframe?

...Let me check in the back shed.
Or

You can accept LH2 vehicles have special challenges and split the task into a highly insulated tank (handling the dead weight of the LH2 and the acceleration loads on it) and an outer fuselage handling the aerothermal loads.

Which is how every LH2 fueled aircraft concept since the original Suntan has planned to handle it.

And which is how Skylon will handle it.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 02/08/2016 09:12 am
I have been thinknig, of late, at a different military application for a Sabre-based vehicle. Let's say, a small-ish drone carrying anti-sat weaponry which jumps to LEO, releases its small payload, and goes back. How small can a sabre-based vehicle be made? I am sure there is a downard limitation...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Stormbringer on 02/08/2016 02:25 pm
The problem with that as I see it is we already have ASAT capability even from something as small as conventional fighter jets, big bombers, and naval destroyers. developing a sabre derivative for the same thing wouldn't at first glance seem logical.

*shakes REL box to encourage faster news delivery*



Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hanelyp on 02/08/2016 04:24 pm
Killing a satellite doesn't require the kill device to reach orbit.  It's enough for the device to be in the right spot for the satellite to hit it.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 02/08/2016 04:41 pm
The problem with that as I see it is we already have ASAT capability even from something as small as conventional fighter jets, big bombers, and naval destroyers. developing a sabre derivative for the same thing wouldn't at first glance seem logical.

*shakes REL box to encourage faster news delivery*

true. But most of these methods are devastating in terms of space environment. Maybe blinding lasers would be more effective than from the ground?

Just speculating of course.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 02/08/2016 06:18 pm
Responding generally to the idea of ASAT, I would have thought Skylon/whatever is far more appropriate to the opposite side of the equation - replacing satellites that have been knocked out.

One might imagine that putting satellites in space purely for a contingency costs money and allows them to become obsolete and allows an enemy to study them and try to intercept their communications.  So you could leave your war-winning system in a mountain somewhere, continually improving it  and launch it only at need - if you could do it fairly rapidly.   What would be? An ASAT defence system? A surge in the number of satellites for some observation system that is already in orbit giving it much higher resolution?   Star wars mk2? Something anyhow that you could hide from your foes and surprise them with.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 02/08/2016 06:39 pm
It's an interesting question: would affordable launch (if enabled by Skylon and others) make ASAT development less attractive because assets can be easily replaced, or more likely because space-based weapons can be launched on smaller budgets... That question probably deserves a new thread, though.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 02/08/2016 11:20 pm
The problem with that as I see it is we already have ASAT capability even from something as small as conventional fighter jets, big bombers, and naval destroyers. developing a sabre derivative for the same thing wouldn't at first glance seem logical.

*shakes REL box to encourage faster news delivery*

true. But most of these methods are devastating in terms of space environment. Maybe blinding lasers would be more effective than from the ground?

Just speculating of course.

Iran and China have been blinding US satellites for years using lasers.

http://www.ynetnews.com/articles/0,7340,L-4162770,00.html (http://www.ynetnews.com/articles/0,7340,L-4162770,00.html)

http://www.telegraph.co.uk/news/worldnews/1529864/Beijing-secretly-fires-lasers-to-disable-US-satellites.html (http://www.telegraph.co.uk/news/worldnews/1529864/Beijing-secretly-fires-lasers-to-disable-US-satellites.html)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 02/09/2016 08:38 am
The problem with that as I see it is we already have ASAT capability even from something as small as conventional fighter jets, big bombers, and naval destroyers. developing a sabre derivative for the same thing wouldn't at first glance seem logical.

*shakes REL box to encourage faster news delivery*

true. But most of these methods are devastating in terms of space environment. Maybe blinding lasers would be more effective than from the ground?

Just speculating of course.

Iran and China have been blinding US satellites for years using lasers.

http://www.ynetnews.com/articles/0,7340,L-4162770,00.html (http://www.ynetnews.com/articles/0,7340,L-4162770,00.html)

http://www.telegraph.co.uk/news/worldnews/1529864/Beijing-secretly-fires-lasers-to-disable-US-satellites.html (http://www.telegraph.co.uk/news/worldnews/1529864/Beijing-secretly-fires-lasers-to-disable-US-satellites.html)

I am aware, but sending a laser to cut through the deep planet atmosphere does not sound very efficient. A Skylong-based system instead would be able to reach low orbit, disable the target satellite with much larger laser efficiency, and turn back.

It's an interesting question: would affordable launch (if enabled by Skylon and others) make ASAT development less attractive because assets can be easily replaced, or more likely because space-based weapons can be launched on smaller budgets... That question probably deserves a new thread, though.

I agree it deserves a new topic, although Skylon is related. However, so far, only a country is seriously developing reusable launchers, so it is not yet worth discussing strategically...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 02/09/2016 07:52 pm
I have been thinknig, of late, at a different military application for a Sabre-based vehicle. Let's say, a small-ish drone carrying anti-sat weaponry which jumps to LEO, releases its small payload, and goes back. How small can a sabre-based vehicle be made? I am sure there is a downard limitation...
It depends.

The joker in the pack is the chamber pressure.  The physical properties of LH2 make building small high pressure LH2 pumps very difficult. During talks about their ground based test engine planned to go with pressure feeding as designing such a pump would take up most (if not all) of their planned budget.

I'm still hoping the do a full size (but not flight weight) engine.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Dalhousie on 02/09/2016 11:50 pm

Iran and China have been blinding US satellites for years using lasers.

http://www.ynetnews.com/articles/0,7340,L-4162770,00.html (http://www.ynetnews.com/articles/0,7340,L-4162770,00.html)

http://www.telegraph.co.uk/news/worldnews/1529864/Beijing-secretly-fires-lasers-to-disable-US-satellites.html (http://www.telegraph.co.uk/news/worldnews/1529864/Beijing-secretly-fires-lasers-to-disable-US-satellites.html)

Poorly supported speculation a 5-10 years old that probably is not relevant here.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 02/13/2016 12:24 pm
The problem with that as I see it is we already have ASAT capability even from something as small as conventional fighter jets, big bombers, and naval destroyers. developing a sabre derivative for the same thing wouldn't at first glance seem logical.

*shakes REL box to encourage faster news delivery*

true. But most of these methods are devastating in terms of space environment. Maybe blinding lasers would be more effective than from the ground?

Just speculating of course.

Iran and China have been blinding US satellites for years using lasers.

http://www.ynetnews.com/articles/0,7340,L-4162770,00.html (http://www.ynetnews.com/articles/0,7340,L-4162770,00.html)

http://www.telegraph.co.uk/news/worldnews/1529864/Beijing-secretly-fires-lasers-to-disable-US-satellites.html (http://www.telegraph.co.uk/news/worldnews/1529864/Beijing-secretly-fires-lasers-to-disable-US-satellites.html)
Quote
I am aware, but sending a laser to cut through the deep planet atmosphere does not sound very efficient. A Skylong-based system instead would be able to reach low orbit, disable the target satellite with much larger laser efficiency, and turn back.
These systems aren't designed to permanently disable satellites, just to blind them and prevent them taking clear pictures of what going on on the ground.

Space base weapons is vastly more costly, why achieving the same thing as ground base lasers, blinding your opponents to your activities. Plus you less likely to trigger international incident if you just blinding a satellite instead of shooting it down.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 02/16/2016 10:40 am
The problem with that as I see it is we already have ASAT capability even from something as small as conventional fighter jets, big bombers, and naval destroyers. developing a sabre derivative for the same thing wouldn't at first glance seem logical.

*shakes REL box to encourage faster news delivery*

true. But most of these methods are devastating in terms of space environment. Maybe blinding lasers would be more effective than from the ground?

Just speculating of course.

Iran and China have been blinding US satellites for years using lasers.

http://www.ynetnews.com/articles/0,7340,L-4162770,00.html (http://www.ynetnews.com/articles/0,7340,L-4162770,00.html)

http://www.telegraph.co.uk/news/worldnews/1529864/Beijing-secretly-fires-lasers-to-disable-US-satellites.html (http://www.telegraph.co.uk/news/worldnews/1529864/Beijing-secretly-fires-lasers-to-disable-US-satellites.html)
Quote
I am aware, but sending a laser to cut through the deep planet atmosphere does not sound very efficient. A Skylong-based system instead would be able to reach low orbit, disable the target satellite with much larger laser efficiency, and turn back.
These systems aren't designed to permanently disable satellites, just to blind them and prevent them taking clear pictures of what going on on the ground.

Space base weapons is vastly more costly, why achieving the same thing as ground base lasers, blinding your opponents to your activities. Plus you less likely to trigger international incident if you just blinding a satellite instead of shooting it down.

yes, but the "mission profile" is not a peacetime attempt to decrease a competitor's capacities without provoking international unease.
Rather, it is becoming clear that any large scale conflict of the future will be  chacraterised by attempts to achieve space dominance first. having a reliable, quick and cheap launcher, copuled with a modified version capable of taking down the opponent's assets, is a game changer in that scenario.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 02/20/2016 03:40 pm
The lack of news is making me feel a bit grim, being a news junkie.

I read that there's a talk at the University of Nottingham by Mark Thomas on 15 March at 5:30 pm.   I'm posting this in the hope that someone will be able to go as it looks like there's no chance of me being able to do it.

http://www.tinyurl.com/SABRElecture

The University of Nottingham - Engineering & Science Learning Centre (ESLC), B01. University Park. Nottingham NG7 2RD GB
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 02/21/2016 05:21 pm
I just realised that I forgot a list of questions.  Perhaps we should suggest some in case someone has a chance to ask them?

For me:

1) What's the response to the recent economic analysis from Ashley Dove-Jay at Bristol University that cast an unfavourable light on Skylon's economics? I'm not trying to be aggressive about this because it's obvious that everything depends on a set of assumptions. I just want to know what REL thinks.

2) The other thing I want to ask is if they feel like commenting on the issue raised by NASA Ames about the temperature at the tail.







Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Lar on 02/23/2016 04:41 pm
Hey guess what, guys and girls??? I just discovered an astounding thing. ** this thread is NOT about SpaceX **

Trimmed.

Posts sent to sleep with the fishes.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 02/25/2016 02:46 pm
yes, but the "mission profile" is not a peacetime attempt to decrease a competitor's capacities without provoking international unease.
Rather, it is becoming clear that any large scale conflict of the future will be  chacraterised by attempts to achieve space dominance first. having a reliable, quick and cheap launcher, copuled with a modified version capable of taking down the opponent's assets, is a game changer in that scenario.
The subject is referred to as "Responsive space" by the USAF and they have organized several conferences on it. AFAIK the proceedings are online.

One of the things you discover when you study this subject is that reusability is not enough

The vehicle must be able to launch on a consistent basis IE a regular "service" should be possible.

Likewise customers must know that their payload will not be dropped off the manifest for no reason they can control. This was one of the frustrations with (IIRC) McDonald Douglas's work on protein separation. It was only (IIRC) a couple of mid deck lockers but was one of the few serious efforts to do commercial research in space for short term payback. It kept getting put back. This is death to any sort of development schedule.

Please keep in mind REL reckon a 2 day turnaround is possible but its payload is 15 tonnes to LEO, whereas a Delta IV Heavy is looking at 24 tonnes. It would simply not be able to replace some of the bigger NRO payloads. Wheather you need all that mass, or could split the payload into multiple single instrument satellites under 15 tonnes (or 6 tonnes with the SUS to get them to GTO) is another question.

I would also note a laser killer satellite can be launched just as easily by an ELV and if left attached to Skylon would have a life on orbit of about 4-6 days, because Skylon is expected to deliver stuff to orbit then return, a process taking about a day for return to the original launch site, but rather less if people are OK with it landing, picking up LH2 and self ferrying back to base.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Til800?CU on 02/26/2016 11:02 pm
I am curious is not the laser approach superseding "engine" tech so should not efforts be thinking on coming up for better ideas in that line of direction?  ::)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 02/26/2016 11:49 pm
Rockets for lift-off take on the order of Gigawatts of power. This is why laser launch isn't terribly practical except for very small rockets, which still would need many megawatts.

People often underestimate just how much power is involved with modern rockets. Falcon Heavy, for instance, would produce on the order of 60 Gigawatts. BFR would be 200-300 Gigawatts, i.e. half the average US electric grid output.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Til800?CU on 02/27/2016 02:25 am
Rockets for lift-off take on the order of Gigawatts of power. This is why laser launch isn't terribly practical except for very small rockets, which still would need many megawatts.

People often underestimate just how much power is involved with modern rockets. Falcon Heavy, for instance, would produce on the order of 60 Gigawatts. BFR would be 200-300 Gigawatts, i.e. half the average US electric grid output.

Indeed I was thinking more "in space" not lift off ;)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: R7 on 02/27/2016 11:41 am
<lasers>

Indeed I was thinking more "in space" not lift off ;)

Laser in space propulsion does not belong to Skylon thread. Photonic propulsion thread (http://forum.nasaspaceflight.com/index.php?topic=39643.0) is more suitable.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Til800?CU on 02/27/2016 09:01 pm
I was just sayin if we as human species are going to the stars then maybe we want to go faster :)  8)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Soundbite on 02/29/2016 11:58 am
The Science and Technology Committee: Satellites and Space Inquiry have just published their minutes http://data.parliament.uk/writtenevidence/committeeevidence.svc/evidencedocument/science-and-technology-committee/satellites-and-space/oral/29543.pdf (http://data.parliament.uk/writtenevidence/committeeevidence.svc/evidencedocument/science-and-technology-committee/satellites-and-space/oral/29543.pdf).  There were some interesting contributions from Mark Thomas, such as that they still haven't seen any of the £60M funds that Osborne promised in 2013...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 02/29/2016 07:14 pm
The Science and Technology Committee: Satellites and Space Inquiry have just published their minutes http://data.parliament.uk/writtenevidence/committeeevidence.svc/evidencedocument/science-and-technology-committee/satellites-and-space/oral/29543.pdf (http://data.parliament.uk/writtenevidence/committeeevidence.svc/evidencedocument/science-and-technology-committee/satellites-and-space/oral/29543.pdf).  There were some interesting contributions from Mark Thomas, such as that they still haven't seen any of the £60M funds that Osborne promised in 2013...

Many many thanks for that.  I found the whole thing interesting - not just the reaction engines bit. 

I noticed what seemed like a rather competitive attitude towards RE from several of the witnesses. There were comments about how the UK should not trying to do anything new that competes with what other countries have spent a lot of money on  since it would be hard for the UK to have any advantage.   The argument was  that money could be directed to the places where the UK already had an "edge" so that it can maintain that.

Then there was some water-muddying which seemed a little unprofessional to me regarding the cost of a launcher.   There are all sorts of places to look for evidence but this rather old link http://spacenews.com/39906former-arianespace-chief-says-spacex-has-advantage-on-cost/ suggests that Mark Thomas was not wrong and that perhaps they were talking about somewhat different things.  Nevertheless I felt there was some degree of animosity that you get when people are competing for attention and of course the possibility of getting money.   

Then there was a comment about the spaceport and horizontal launch to the effect of "lets not choose something for which the technology and business case don't exist"  -  which seemed entirely aimed at RE.

It made me see why the space industry in the UK might not be too keen on Skylon/SABRE being a success as they see it soaking up government money that they want. Since they are satellite makers or buyers they see launching as something they are not competing in internationally and they obviously feel that if a new launcher is created by e.g. SpaceX then they can buy rides on it like anyone else - no need for the UK to blow any cash that could instead be spent of making their actual products more competitive.

I don't accept this viewpoint of course because I am an RE fanboi and because to a degree these companies are either big enough to look after themselves or profitable even if small and to some degree they have had their cake and should be able to generate investment interest if they really have something to offer, some big plan to execute.

Anyhow perhaps it's just my mindset that I saw it this way. :-)  The bit about RE not having any of the money yet is just ridiculous but it's interesting to see how things happen.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 02/29/2016 11:02 pm
Sadly that just like Cameron and Osborn all talk and very very little in the way of action. In fact I can't remember a single pledge they have actually fulfilled. So it doesn't surprise me that their pledge of funds to RE have yet to be fulfilled.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Ravenger on 03/01/2016 09:34 am
The main problem with dealing with governments and big organizations is the bureaucracy and the time it takes them to do anything.

One reason for the delay in the government's payment is that it had to be referred to the EU, as it could have breached EU state-aid rules. Permission was eventually given for the payment to go ahead, but it took a long while to happen.

Even with that delay, it's still a scandal that the UK government haven't delivered the promised funding by now.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 03/02/2016 01:18 pm
In reference the the parliamentary committee where Mark Thomas mentioned that Reaction engines was going to be short of people with experience in rocket engines:

https://www.flightglobal.com/news/articles/analysis-ariane-6-launch-cost-assault-is-a-revoluti-422239/

I don't want to get too far off the topic - the article just says that "too many people are employed in building Ariane rockets"  and details how this is going to be remedied.   So that might solve RE's problem in finding people with the right experience.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/02/2016 07:24 pm
The Science and Technology Committee: Satellites and Space Inquiry have just published their minutes http://data.parliament.uk/writtenevidence/committeeevidence.svc/evidencedocument/science-and-technology-committee/satellites-and-space/oral/29543.pdf (http://data.parliament.uk/writtenevidence/committeeevidence.svc/evidencedocument/science-and-technology-committee/satellites-and-space/oral/29543.pdf).  There were some interesting contributions from Mark Thomas, such as that they still haven't seen any of the £60M funds that Osborne promised in 2013...
This is very disappointing.

It would seem they have taken the government at it's word. Always a doubtful proposition.  :(

By all means wait till a reasonable amount of time has gone by but once the deadline is passed they really needed to have started seriously chasing this.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 03/03/2016 12:25 am
In reference the the parliamentary committee where Mark Thomas mentioned that Reaction engines was going to be short of people with experience in rocket engines:

https://www.flightglobal.com/news/articles/analysis-ariane-6-launch-cost-assault-is-a-revoluti-422239/

I don't want to get too far off the topic - the article just says that "too many people are employed in building Ariane rockets"  and details how this is going to be remedied.   So that might solve RE's problem in finding people with the right experience.
Continuous development went missing on a lot of rockets in the past. It be interesting to see if Arianespace/ Airbus Safran Launchers will be able to keep up continuous development of Vega and Ariane rockets. An where the money for this continuous development will come from there own funds or from government.

I'm surprise to see the French give up the 1/3 of Arianespace they own. That must have took a lot of convincing.   
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 03/03/2016 06:45 am
Continuous development went missing on a lot of rockets in the past. It be interesting to see if Arianespace/ Airbus Safran Launchers will be able to keep up continuous development of Vega and Ariane rockets. An where the money for this continuous development will come from there own funds or from government.

I'm surprise to see the French give up the 1/3 of Arianespace they own. That must have took a lot of convincing.

Another thing that I note as interesting is that they claim that horizontal payload integration is going ot be faster and cheaper.   This reminds me of the debate earlier on about whether Skylon had advantages for that reason - if this is actually significant for Ariane 6 then presumably it would also be for a Skylon.

Presumably the other ideas about having an assembly line for  engines etc don't apply so much to SABRE unless there's a huge order book.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 03/03/2016 11:58 am
The Science and Technology Committee: Satellites and Space Inquiry have just published their minutes http://data.parliament.uk/writtenevidence/committeeevidence.svc/evidencedocument/science-and-technology-committee/satellites-and-space/oral/29543.pdf (http://data.parliament.uk/writtenevidence/committeeevidence.svc/evidencedocument/science-and-technology-committee/satellites-and-space/oral/29543.pdf).  There were some interesting contributions from Mark Thomas, such as that they still haven't seen any of the £60M funds that Osborne promised in 2013...
This is very disappointing.

It would seem they have taken the government at it's word. Always a doubtful proposition.  :(

By all means wait till a reasonable amount of time has gone by but once the deadline is passed they really needed to have started seriously chasing this.

Britain starts a new financial year on the 5th April. Making noises before then can backfire badly.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 03/03/2016 02:00 pm
"USAF set to unveail concept based on Skylon technology"


key takeaways:

- two 2STO concepts based on SABRE will be unveiled either in September or in March 2017
- a competition had been launched in February this year for in-flight testing of the SABRE precoolers.


http://www.space.com/32115-skylon-space-plane-engines-air-force-vehicle.html?cmpid=514648
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 03/03/2016 02:11 pm
a SABRE- based first stage for USAF, then.
How would it fit with the second stage based on RAPTOR that USAF is also developing?
Would such architecture mixinx REL & SpaceX technologies provide  ground for a 2stage full reusable system?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/03/2016 03:36 pm
a SABRE- based first stage for USAF, then.
How would it fit with the second stage based on RAPTOR that USAF is also developing?

Might not use the Raptor at all, they could use the something similar to the SMV set-up in this report:
http://www.sei.aero/eng/papers/uploads/archive/SEI_JANNAF_Sentinel_2007_present.pdf (Page 18)

Or if they do they've been "thinking" about using Falcon derived upper stages for a while now:
http://www.sei.aero/eng/papers/uploads/archive/SEI_JANNAF_Spiral2_2007.pdf
http://www.sei.aero/eng/papers/uploads/archive/AIAA-2006-8057.pdf

Quote
Would such architecture mixinx REL & SpaceX technologies provide  ground for a 2stage full reusable system?

Probably but very different from what SpaceX is looking to.

Examples:
http://www.sei.aero/eng/papers/uploads/archive/AIAA-2004-5950.pdf
http://www.sei.aero/eng/papers/uploads/archive/GT-SSEC-B.1_present.pdf
https://mdao.grc.nasa.gov/publications/TETS-2010_TBCC-JSS.pdf
http://sites.nationalacademies.org/cs/groups/depssite/documents/webpage/deps_068007.pdf

Mostly because it IS the "Air Force Research Laboratory" and once they move past expendable upper stages they tend to put wings on everything anyway :) I'm not going to be at all surprised either if they (AFRL that is) don't find some way to stick a SCramjet on the concepts as well.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 03/03/2016 03:50 pm
"USAF set to unveail concept based on Skylon technology"


key takeaways:

- two 2STO concepts based on SABRE will be unveiled either in September or in March 2017
- a competition had been launched in February this year for in-flight testing of the SABRE precoolers.


http://www.space.com/32115-skylon-space-plane-engines-air-force-vehicle.html?cmpid=514648

Here we go again, another Frank Whittle moment !!!
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Asteroza on 03/03/2016 10:23 pm
For TSTO, the trajectory profile should be basically the same as the current Skylon suborbital max payload throw as currently envisioned, right? For reference, what's the max suborbital throw weight? As a rough figure of merit, with said upperstage, what are we looking as payload to a minimal parking/checkout orbit assuming the payload can electric thrust its way elsewhere?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 03/03/2016 11:00 pm
So the Air Force has found a concept that allows them to maximize system cost while minimizing the advantages? I mean... What should a two stag concept be good for? You replace a simple and scalable booster with an expensive SABRE design just to then add a second stage? Why???
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 03/04/2016 12:06 am
Anyone else building precoolers other than Reaction Engines?. Here hoping this isn't an attempt by the air force to replicate Reaction Engine technologies in the US without Reaction engine involvement.

Spacex Raptor program is design for this generation of space launch vehicles, one presume this would be next generation of launch vehicles.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 03/04/2016 12:10 am
So the Air Force has found a concept that allows them to maximize system cost while minimizing the advantages? I mean... What should a two stag concept be good for? You replace a simple and scalable booster with an expensive SABRE design just to then add a second stage? Why???
Let the US figure that out, Reaction Engine will just build the engine, what other people do with them is their choice, hopefully Reaction engine will have enough money left over to continue their development of a SSTO Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alpha_Centauri on 03/04/2016 09:25 am
Anyone else building precoolers other than Reaction Engines. Here hoping this isn't an attempt by the air force to replicate Reaction Engine technologies in the US without Reaction engine involvement.

That was inevitable once REL started working with the Americans. Tbh I would rather someone, anyone, take the technology forward rather than it remain a pretty PowerPoint.  It's a shame, but this country has become far too myopic.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 03/05/2016 02:22 am
"USAF set to unveail concept based on Skylon technology"
http://www.space.com/32115-skylon-space-plane-engines-air-force-vehicle.html?cmpid=514648

Hmmm...

Quote
"The oxygen in the chilled air will become liquid in the process."

Unless the USAF really does intend to turn REL's (or equivalent) pre-coolers into LACE, I suspect this in a standard Space.com "near enough" article. So I wouldn't read too much into the details.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: momerathe on 03/05/2016 08:10 pm
Let the US figure that out, Reaction Engine will just build the engine, what other people do with them is their choice,
Really, this should be what REL are doing. I've always found their "this is our design for a spaceplace guys - by the way, we want someone else to build it" stance to be a little contradictory.

Quote
hopefully Reaction engine will have enough money left over to continue their development of a SSTO Skylon.
or at least let AFRL pay to get the first engine flying; once that's done, building a second gets that much easier, and other investors that much easier to find.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 03/05/2016 09:12 pm
So the Air Force has found a concept that allows them to maximize system cost while minimizing the advantages? I mean... What should a two stag concept be good for? You replace a simple and scalable booster with an expensive SABRE design just to then add a second stage? Why???

Because a two stage system gives greater design margins.  A lot of experienced people believe Skylon has a lot of design risk because it's single-stage to orbit.  With two stages, there's more margin to work with, so the design doesn't have to push the edge of what's possible in so many ways, and there's more margin for making it more cost-effective.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 03/05/2016 09:14 pm
So the Air Force has found a concept that allows them to maximize system cost while minimizing the advantages? I mean... What should a two stag concept be good for? You replace a simple and scalable booster with an expensive SABRE design just to then add a second stage? Why???

Because a two stage system gives greater design margins.  A lot of experienced people believe Skylon has a lot of design risk because it's single-stage to orbit.  With two stages, there's more margin to work with, so the design doesn't have to push the edge of what's possible in so many ways, and there's more margin for making it more cost-effective.

Plus, with two stages you can get the same payload to orbit with a smaller overall vehicle, or a larger payload to orbit with the same size vehicle.  Smaller size means lower cost, which can more than offset the additional complexity of having two stages.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/07/2016 07:07 am
Anyone else building precoolers other than Reaction Engines?. Here hoping this isn't an attempt by the air force to replicate Reaction Engine technologies in the US without Reaction engine involvement.

That's debatable The programme mentioned in the space.com article is described here.

https://www.sbir.gov/sbirsearch/detail/870285

Note the bit upfront about ITAR and how access to USAFRL supecomputing facilities maybe by "qualified" staff only.

The joke is REL would be able to handle both phase I & II without breaking sweat given their prior experience.  :(

Time will tell if this is an effort by USAFRL to fund REL or if they are just trying to drain the tech from REL and inject it into an American company.  I'll note that AFAIK only REL have worked out what to build and how to build it. I sincerely hope REL take precautions to ensure that information remains with them.

IIRC an outfit called Andrews Aerospace has been pushing something called "Air Collection and Enrichment System" for decades, which is basically LACE. Somehow the words "Enthalpy of Vaporization" just don't seem to mean anything to them.

But SABRE is a launch engine, not a cruise engine.  It's designed to go Mach 0-23. If you want less, get a different design.  :(

Or (just throwing this idea out there) the USAF could pay REL to design a cruise engine, like normal customers do when they want something for a special purpose.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/07/2016 07:29 am
Plus, with two stages you can get the same payload to orbit with a smaller overall vehicle, or a larger payload to orbit with the same size vehicle.  Smaller size means lower cost, which can more than offset the additional complexity of having two stages.
The current Skylon user manual gives a GTOW of 325 tones for a 15 tonne payload

That's a payload fraction of  4.6%

Which is better than a Delta IV, the nearest big LH2 LV around and probably better than an F9, given SX are remarkably secretive about such things.

Vertical Takeoff RLV's have always sacrificed payload fraction.  VTO SSTO's have sacrificed a lot of payload.

Skylon was designed to deliver a TSTO ELV payload fraction because its designers know there is no point in trying to raise funding for anything less.

Because a two stage system gives greater design margins. 
It's believed a TSTO design give greater margins.

So how come only 2 large designs in the 1930's were 2 stage aircraft? All commercial aircraft are "single stage."

Let's be clear the hidden message in this thinking is "we messed up the design of a stage, the other stage will compensate."

Why? Because the other stage will magically be better designed ? That might be true if the stages (like Saturn) were designed by different companies.

A single company is likely to end up with two underperforming stages instead of one.
Quote
A lot of experienced people believe Skylon has a lot of design risk because it's single-stage to orbit.  With two stages, there's more margin to work with, so the design doesn't have to push the edge of what's possible in so many ways, and there's more margin for making it more cost-effective.
AFAIK no one has experience of designing a successful SSTO of any kind, so who are these "experienced" people?

SABRE is designed to go the whole distance both in terms of speed and altitude. Skylon is designed to do the same. Splitting the task means..

(2 engine designs  + 2 vehicle designs + all their testing) x all the interactions between those stages.

Like the "Let's make a good TSTO ELV and then turn both stages into an RLV" meme it's one of those notions that sounds really sensible, and low risk but does in fact have an unquantifiable level of risk attached to it, to the point that one mfg has abandoned further efforts to do so with its existing architecture.

In contrast thousands of aircraft designs have gone from drawing board (and now CAD screen) to takeoff. Single stage winged vehicles have done sustained flight to M3.3+ and the X15 to M7+ for long enough to understand the issues. The Shuttle showed winged lift could handle M23 to M0 as well.

As the X30 programme showed the biggest risk of a HTOL SSTO is the engine and SABRE can be tested well enough on the ground that vehicle designers can be confident if their structural engineering is good enough it can get the job done.

If you're looking to get to LEO in a reusable system with minimum risk (and  you don't have some hobby horse to ride, like nuclear weapons delivery) you'd look at what flight regimes have the biggest knowledgebase you could leverage.

You'd also note that HTO means thrust can be 1/3 of GTOW rather than 1.1x (or more) of GTOW for VTOL systems.

But then you'd note there was no engine around that could the full range with adequate Isp and go back to rockets, which are also quite simple to model, relative to air breathing systems.

For pragmatic people who don't have a pet system to champion SABRE is a game changer.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: chipguy on 03/07/2016 04:38 pm

The current Skylon user manual gives a GTOW of 325 tones for a 15 tonne payload

That's a payload fraction of  4.6%

Which is better than a Delta IV, the nearest big LH2 LV around and probably better than an F9, given SX are remarkably secretive about such things.


The key difference here is that DIV and F9 exist today and are launching payloads.

Skylon is a concept remarkably short of actual full scale technology demonstration of either propulsion or
vehicle structure and TPS. A slight shortfall in the performance of the former or underestimation of the
mass of the latter could reduce its SSTO performance from 15 tons to not reaching orbit at all with zero
payload.

Saying Skylon is *better* than a working system is nonsense. Maybe some day it might but I wouldn't
bet on it. The user manual for a non-existent system is science fiction.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 03/07/2016 05:44 pm

Saying Skylon is *better* than a working system is nonsense. Maybe some day it might but I wouldn't
bet on it. The user manual for a non-existent system is science fiction.

Surely someone has to think "it is better" of a non-existent thing before they could be bothered to get out of bed and make it real?

Did the SpaceX founders think their non-existent clean sheet implementation would be better?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: chipguy on 03/07/2016 09:39 pm

Surely someone has to think "it is better" of a non-existent thing before they could be bothered to get out of bed and make it real?

Did the SpaceX founders think their non-existent clean sheet implementation would be better?

Aspiring to do better than current solutions is what engineers like me do every day.

However, look at the tense of claim the previous poster made: " That's a payload fraction of  4.6%
Which is better than a Delta IV, the nearest big LH2 LV around and probably better than an F9"

You can't correctly claim that X is better than Y when Y exists and X doesn't. This especially true
when that claim about X is based on the development and perfection of technology that has never
been demonstrated before. X doesn't exist. A prototype of X or its engine doesn't exist. Performance
claims have to be taken with a freighter full of salt. History of this industry leads one to be sceptical.

A factually correct claim is "if X can be developed and if it performs up to the hopes of its proponents
then...". Anything stronger or more definite than that is intellectually dishonest.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 03/07/2016 11:54 pm
To state the obvious: This thread is in Advanced Concepts. So off the bat we know that: 1] it doesn't exist yet, 2] people are interested in discussing the concept, and if/how it might come to exist.

So posts that point out it doesn't exist, and/or rush to conclude that it won't ever exist, or isn't worth discussing, really aren't moving the conversation forward very far...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 03/07/2016 11:59 pm
A slight shortfall in the performance of the former or underestimation of the mass of the latter could reduce its SSTO performance from 15 tons to not reaching orbit at all with zero payload.

We've been over this before.  It's not a matter of a "slight shortfall"; this is not an all-rocket SSTO and is nowhere near as sensitive to either mass growth or engine underperformance.

According to my calculations, based on the numbers in the 2014 NISSIG presentation (http://forum.nasaspaceflight.com/index.php?topic=33648.msg1171426#msg1171426)*, total payload loss would require one of:  A) an 11.6% Isp loss across both engine modes, B) a 12.2% rocket Isp loss with no airbreathing performance loss, C) a 72% loss of airbreathing Isp with no rocket performance loss, D) 30.5% dry mass growth, or E) some combination of the above.

But that's assuming no mass margin is being carried in the design, which is not accurate; they claim they're using mass growth margins "consistent with AIAA guidelines" for Skylon D1, which to me means at least 15% (IIRC their structural calculations for Skylon C1 back in the day used 15%).  Recalculating with dry mass divided by 1.15 results in the scenarios becoming:  A) a 16.8% Isp loss across both engine modes (for perspective, this would be like the SSME coming in at 379 s vac), B) a 17.5% rocket Isp loss with no airbreathing performance loss, C) an 80% loss of airbreathing Isp with no rocket performance loss, D) 50% dry mass growth, or E) some combination of the above.

* 325,000 kg at start of roll (from which I have subtracted 1,418 kg of brake water, under the assumption that not carrying it through the takeoff roll won't affect the numbers much), 299,819 kg at transition, 73,435 kg at MECO, 52,347 kg dry.  Payload to standard orbit is 15,000 kg with 986 kg performance margin.  For the purpose of these calculations, I have assumed that lost payload due to underperformance is subtracted from GTOW - ie: the vehicle is not being redesigned either to have lower dry mass or to carry more propellant in place of the lost payload.

intellectually dishonest.

It's shorthand, not intellectual dishonesty.  This thread would be way harder to read (and much more annoying to post to) if everyone had to rigorously finesse every single statement like you're demanding.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/08/2016 09:57 am

Skylon is a concept remarkably short of actual full scale technology demonstration of either propulsion or
vehicle structure and TPS.
I see. So Skylon lacks a full scale demonstration because no one has built a Skylon yet. That alone makes you a doubter rather than a skeptic.

Your name suggests you deal with logic devices.

Do you understand the concept of a circular argument?
Quote
A slight shortfall in the performance of the former or underestimation of the
mass of the latter could reduce its SSTO performance from 15 tons to not reaching orbit at all with zero
payload.
You're thinking like it's a VTOL SSTO, where thrust must exceed GTOW just to lift off and you're structure mas can be no more than about 3% to give a payload of 1%, which is historically what Bono style VTOL have accepted.
Quote
Saying Skylon is *better* than a working system is nonsense. Maybe some day it might but I wouldn't
bet on it. The user manual for a non-existent system is science fiction.
Funny. I've seen plenty of semiconductor documentation marked "provisional."

In some cases I doubt they have even done the floor planning for the chip before telling the world it'll be available by next April, or whenever, yet they behave as if it will happen, and a lot of the time it does.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/08/2016 09:58 am
To state the obvious: This thread is in Advanced Concepts. So off the bat we know that: 1] it doesn't exist yet, 2] people are interested in discussing the concept, and if/how it might come to exist.

So posts that point out it doesn't exist, and/or rush to conclude that it won't ever exist, or isn't worth discussing, really aren't moving the conversation forward very far...
Or indeed anywhere.   :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 03/08/2016 11:33 am
For the love of Thor. This is a discussion forum. On advanced concepts (stuff that hasn't been built yet).

We all know that. We don't need to repeat it and qualify our comments in very post.   smh
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hanelyp on 03/08/2016 04:38 pm
According to my calculations, based on the numbers in the 2014 NISSIG presentation (http://forum.nasaspaceflight.com/index.php?topic=33648.msg1171426#msg1171426)*, total payload loss would require one of:  A) an 11.6% Isp loss across both engine modes, B) a 12.2% rocket Isp loss with no airbreathing performance loss, C) a 72% loss of airbreathing Isp with no rocket performance loss, D) 30.5% dry mass growth, or E) some combination of the above.
...
LOX-LH2 rocketry is a sufficiently mature tech that a large shortfall is ISP seems unlikely, even with the novel pump arrangement.  Which, presuming their engineers have done their jobs right, leaves substantial performance margins before complete loss of payload.  Allowing for the 15% margin looks even better.  Of course any payload loss reduces the economic margins of viability.

Taking the above as reliable, the biggest uncertainty may be maintenance requirements between flights.  Uncontained inspection and repair costs might render the whole system uneconomic even if full performance is delivered.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: chipguy on 03/08/2016 05:03 pm
I see. So Skylon lacks a full scale demonstration because no one has built a Skylon yet. That alone makes you a doubter rather than a skeptic.

Your name suggests you deal with logic devices.

Do you understand the concept of a circular argument?

The DIV and F9 have existence proof of performance.

Skylon is a paper design relying on technologies yet to be demonstrated. I am all in favour of innovation
and progress and new ideas.

What I don't like is someone touting something hypothetical as if it was real and had proven performance.
An awful lot of things have to go very right for Skylon to live up to expectations. The history of attempting
to mix wings and/or air-breathing and/or hybrid propulsion systems with space flight suggests a healthy
scepticism is in order.

Quote
Funny. I've seen plenty of semiconductor documentation marked "provisional."

In some cases I doubt they have even done the floor planning for the chip before telling the world it'll be available by next April, or whenever, yet they behave as if it will happen, and a lot of the time it does.

I have never worked for such an organization. We disclose new products after we have thoroughly tested
them, have built thousands to assess manufacturability margins and ability to meet specifications with
good yield, and have performed extensive accelerated aging and stress tests to assure product operating
lifetimes.

OTOH you seem to be setting up a strawman to justify your touting Skylon so highly for an unbuilt system
relying on unproven technologies ("see, everybody does it"). The fact that you chose semiconductors as your
strawman category IMO hints at thinly veiled ad hominem attack.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 03/08/2016 07:46 pm
I still see no reply to the very informative post of 93143. Any one with better numbers? let's have a polite discussion on how much off the design must be not to deliver. We all want to see the calculations of those claiming the margins are really small.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/09/2016 07:13 am
LOX-LH2 rocketry is a sufficiently mature tech that a large shortfall is ISP seems unlikely, even with the novel pump arrangement.  Which, presuming their engineers have done their jobs right, leaves substantial performance margins before complete loss of payload. 
The design of the SSME was off it's predicted Isp by about 3 secs. Note this was only the 2nd staged combustion engine built in the US and the first (and only) LH2 engine. That's 0.66% for a first of a kind (SC of LH2) design.  This suggests the rocket part at least is fairly well understood.
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Taking the above as reliable, the biggest uncertainty may be maintenance requirements between flights.  Uncontained inspection and repair costs might render the whole system uneconomic even if full performance is delivered.
That's definitely one of the areas that the flight test programme will answer, to quantify damage between flights.

Note that while the Shuttle relied on a small army (several 100 staff IIRC) to inspect and repair the tiles & blankets a clean sheet design including the ConOps would incorporate embedded damage sensors in the airframe (NASA developed miniature remote reading data loggers to be dropped in the gaps between tiles to detect over temperature events. Multiple other options, including FO strain systems are possible) or an external scanning system as Carnegie Mellon proposed in the early 90's to move a sensor package over the whole skin and flag areas for attention.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 03/10/2016 08:49 am
So posts that point out it doesn't exist, and/or rush to conclude that it won't ever exist, or isn't worth discussing, really aren't moving the conversation forward very far...

Except that's exactly what people did when they dismissed the USAF's TSTO proposal.

Yet the same people believe (and aggressively denounce anyone who questions that belief) that REL is so far beyond criticism, that we already know the non-existent Skylon's future payload accurate to one part in one thousand.

Your argument would be more believable if you had applied it in both cases.
Title: The Reaction Engines Skylon Master Thread (5)
Post by: pippin on 03/10/2016 10:03 am
LOX-LH2 rocketry is a sufficiently mature tech that a large shortfall is ISP seems unlikely, even with the novel pump arrangement.  Which, presuming their engineers have done their jobs right, leaves substantial performance margins before complete loss of payload. 
The design of the SSME was off it's predicted Isp by about 3 secs. Note this was only the 2nd staged combustion engine built in the US and the first (and only) LH2 engine. That's 0.66% for a first of a kind (SC of LH2) design.  This suggests the rocket part at least is fairly well understood.
Not necessarily. Don't exactly know what you mean by "first LH2 engine", probably first LH2 staged combustion engine.
But if you look at the development effort you'll see that it had several years of delays and huge cost overruns in development.
As to hitting the ISP: they had to at all cost to make the whole thing viable, 10s less ISP and there goes your payload.

The general theory on how much ISP you can get out of a certain engine setup is pretty well understood, yes. But getting there can be very expensive and time consuming if you lack the experience and especially if it's a high ISP.
Look at Bezos' arguments as to why they are shooting for the mid range for BE4
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Ravenger on 03/10/2016 12:25 pm
There's a new article about Skylon and Sabre at The Verge website:

http://www.theverge.com/2016/3/8/11174670/rel-skylon-spaceplane-announced-jet-engine-rocket-propulsion

One bit of info was new to me:

Quote
"The company plans to test the engines this year"

This is exciting news if true.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 03/10/2016 12:36 pm
There's a new article about Skylon and Sabre at The Verge website:

http://www.theverge.com/2016/3/8/11174670/rel-skylon-spaceplane-announced-jet-engine-rocket-propulsion

One bit of info was new to me:

Quote
"The company plans to test the engines this year"

This is exciting news if true.

Far too soon for engine testing, component testing  yes.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Ravenger on 03/10/2016 12:57 pm
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Far too soon for engine testing, component testing  yes.

Thought it was probably too good to be true.  ::)

Let's hope we get some decent info from REL soon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/10/2016 02:24 pm
I still see no reply to the very informative post of 93143. Any one with better numbers? let's have a polite discussion on how much off the design must be not to deliver. We all want to see the calculations of those claiming the margins are really small.

While it would nice to have such a conversation there are at least two criteria for that to happen;

1) You need the numbers, the ACTUAL numbers to base such a conversation on. The numbers provided by 93143 are the best estimates available from the estimates and assumptions that REL has done so far which is all well and good. But they are still not actual performance figures. If we compare actual, historical numbers... Which was one of the "points" since we can't, no one has designed, built, or operated an SSTO (either horizontal or vertical take off nor by power plant type) so the only available numbers are estimates from previous designs.

2) Everyone has to at least agree on some basic factors to have any chance of discussing the original subject. Which by the way was that "TSTO designs give greater design margins than SSTO designs" which is in fact TRUE and verifiable through historic reference and experience.

Despite John Smith 19 confusing "airplanes" with "spacecraft/spaceplanes" and using the old saw that the former are "SSTO" (which ignores SO many operational and design differences as to have no meaning) so "obviously" having the latter SSTO is the only thing that makes sense, and attacks describing all TSTO designs as "failures" of design-and-engineering, etc, etc the basic fact does not change a bit.

Probably the main question or point of discussion would be how applicable is the SABRE engine design to use on a TSTO vehicle? SABRE on the Skylon is specifically designed for SSTO operations, but we already know from LAPCAT that a similar engine-cycle is applicable to high-speed, in-atmosphere flight so it's not really that much of a stretch to see SABRE being adapted to booster use only even though it is probably less of an efficient use of the system.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/10/2016 02:28 pm
There's a new article about Skylon and Sabre at The Verge website:

http://www.theverge.com/2016/3/8/11174670/rel-skylon-spaceplane-announced-jet-engine-rocket-propulsion

One bit of info was new to me:

Quote
"The company plans to test the engines this year"

This is exciting news if true.

Far too soon for engine testing, component testing  yes.

Really? I was under the impression that REL was planning on testing a "bread-board" SABRE engine system this year. Yes it could be considered "component-testing" but it is testing the components together AS a system in order to refine function and efficiency.

And frankly they need to.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 03/10/2016 03:50 pm

There's a new article about Skylon and Sabre at The Verge website:

http://www.theverge.com/2016/3/8/11174670/rel-skylon-spaceplane-announced-jet-engine-rocket-propulsion

One bit of info was new to me:

Quote
"The company plans to test the engines this year"

This is exciting news if true.

Far too soon for engine testing, component testing  yes.

Really? I was under the impression that REL was planning on testing a "bread-board" SABRE engine system this year. Yes it could be considered "component-testing" but it is testing the components together AS a system in order to refine function and efficiency.

And frankly they need to.

Randy

I am with you on this not sure why the OP thinks they are that far behind.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 03/10/2016 04:08 pm

There's a new article about Skylon and Sabre at The Verge website:

http://www.theverge.com/2016/3/8/11174670/rel-skylon-spaceplane-announced-jet-engine-rocket-propulsion

One bit of info was new to me:

Quote



"The company plans to test the engines this year"

This is exciting news if true.

Far too soon for engine testing, component testing  yes.

Really? I was under the impression that REL was planning on testing a "bread-board" SABRE engine system this year. Yes it could be considered "component-testing" but it is testing the components together AS a system in order to refine function and efficiency.

And frankly they need to.

Randy

I am with you on this not sure why the OP thinks they are that far behind.

They have a massive amount of detailed design work to undertake before  work can start on construction.

I seem to recall Reaction Engines stating engine testing would not start until late 2018/2019

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 03/10/2016 04:11 pm
SpaceX president yesterday declared that first stage reusability would cut prices of max. 30%, meaning a per-kg cost of 2800$. still sure there is no business case for Skylon? even being very pessimistic, it approaches a cost of 1500/2000 $/kg, and the optimistic figure says 600....
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: chipguy on 03/10/2016 04:58 pm
SpaceX president yesterday declared that first stage reusability would cut prices of max. 30%, meaning a per-kg cost of 2800$. still sure there is no business case for Skylon? even being very pessimistic, it approaches a cost of 1500/2000 $/kg, and the optimistic figure says 600....

First of all you have to recognize the *difference* between price and cost. You are using the terms
interchangeably above.

If SpaceX is already offering substantially lower prices than competitors then how should it apply the
cost reduction benefit of first stage re-usability? Smart business practice is to split the cost reduction
bonus between some price reduction, like up to 30%, and increased launch services gross margins to
pay for R&D and build financial resources. Any price reduction is basically an experiment to test TAM
demand elasticity. Putting a toe in the water is sensible rather than leaping in and generating demand
you can't meet and leaving money on the table for the demand you do fill.

Holding back some of the cost reduction also provides flexibility in case a new lower cost competitor,
perhaps using Skylon if it completes development and performs as advertised, appears.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hauerg on 03/10/2016 05:14 pm
SpaceX president yesterday declared that first stage reusability would cut prices of max. 30%, meaning a per-kg cost of 2800$. still sure there is no business case for Skylon? even being very pessimistic, it approaches a cost of 1500/2000 $/kg, and the optimistic figure says 600....
Skylon is so far away from flying that "current" reusable pricing will be irrelevant.
(I like it to be successful, though.) 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/10/2016 06:40 pm
They have a massive amount of detailed design work to undertake before  work can start on construction.

I seem to recall Reaction Engines stating engine testing would not start until late 2018/2019

I think there's some confusion between engine-testing and engine-system testing :)

As I understood it they need to test the various components in a basic configuration (hence the "bread-board" type layout) in order to refine the overall design requirements and system functionality. It won't be an "engine" but the systems of the engine run as a unit to define the design of the actual engine.

They were supposed to run the configuration this year so they could have a basic prototype engine by late 2018/2019.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 03/10/2016 07:12 pm
They have a massive amount of detailed design work to undertake before  work can start on construction.

I seem to recall Reaction Engines stating engine testing would not start until late 2018/2019

I think there's some confusion between engine-testing and engine-system testing :)

As I understood it they need to test the various components in a basic configuration (hence the "bread-board" type layout) in order to refine the overall design requirements and system functionality. It won't be an "engine" but the systems of the engine run as a unit to define the design of the actual engine.

Just to clarify my position on this.

Testing of various components will progress over the next couple of years and then a "non-flight" proof of concept engine will be tested. If the testing proves successful I think they will endeavour to bring an airframe manufacture on board. I still think a first  flight will not happen until around 2028.
Skylon is a post Ariane 6 launcher. It just cannot operate in such a low launch  per year environment.

I expect by the end of the next decade the number of launches per year will be at a totally different level with a responsibility of companies to keep space clear of "trash" . There will be all sorts of large structures in orbit from power generation beamed down to earth, manufacturing in zero gravity and more, all needing service and supply. this is Skylons home ground.

My personal view of course!.



Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/10/2016 07:24 pm
SpaceX president yesterday declared that first stage reusability would cut prices of max. 30%, meaning a per-kg cost of 2800$. still sure there is no business case for Skylon? even being very pessimistic, it approaches a cost of 1500/2000 $/kg, and the optimistic figure says 600....

Actually there is no business "case" for Skylon because of the simple fact there is no Skylon... Yet :)

I'll have to look up the exact quote but as chipguy notes there's a difference between price and cost and which one the "30%" actually applies to AND how SpaceX is applying it.

In general, (all "things" being equal etc :) ) a SSTO vehicle is supposed to be cheaper to operate than a TSTO vehicle due to the factors of only a single vehicle, monolithic maintenance and operations costs, etc. That's why all other transportation systems (supposedly) are "Single Stage" vehicles rather than multiple stages. ("Supposedly" because really all transportation is composed of a "system" of moving the payload from place to place and "technically" more often than not you use several "vehicles/stages" to get it from point A to point B but we don't want to get to confusing or push any analogy to far... Because...)

However, space launch has never been something you can directly "analog" with any other transportation system we have because of numerous factors inherent in it. People tend to default to aviation as an analog because it is a) the "newest" transport system we have, and b) because its the easiest to make comparisons with in general. (Planes and rockets both "take-off" and "land" and in between they "fly" and both carry passengers and cargo, etc. If you really wanted to be more accurate they would compare with ships and water travel because they both pretty much require both a source and destination to be effective and if you "stop" a ship is sits on the water and floats like a rocket does once in-orbit, but as I said NONE of our other transportation systems really are an effective analog in anything but really general terms)

"Space is hard" is a truism and that's when the base line is using multiple stages to get the payload where you want to go. It gets harder with only a single stage and the basic idea that operating and maintaining that single stage will be "cheaper" than doing so with multiple stages tends to not be as true as it would seem. A lot of the assumptions involved are not based on actual data but on extrapolations of other transportation systems and again the analogies (and data) are not as clear cut as it would appear. The fact that most of the data points come from aviation experience do not in fact increase the viability of the data as much as is supposed.

Leaving aside the main point of one being a currently operational, partially reusable system transitioning to a fully reusable (is the hope) system at a later date, while the other is still in the design stage. The Falcon-9 is a Vertical Take-Off, Two-Stage-To-Orbit system whereas the Skylon is a Horizontal Take-Off, Single-Stage-To-Orbit* system and the two vehicles are going to have vastly different flight regimes and well as operations and maintenance schemes. The capabilities are different as well and direct comparison or the use of the former to "prove" any data points on the latter is questionable at best.

Randy
*Technically you COULD do some comparison between Falcon-9 and Skylon as when you get right down to it both are actually "Two-Stage-To-Destination" vehicles in that both require a second stage to deliver the payload to the proper destination and Skylon therefore has to include margin to allow bringing said stage all the way to orbit in it's "payload" but that's a nit and, again, mostly not indicative of comparable capability. But it IS fun to occasionally bring up to tweak people with :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 03/10/2016 10:41 pm
The general theory on how much ISP you can get out of a certain engine setup is pretty well understood, yes. But getting there can be very expensive and time consuming if you lack the experience and especially if it's a high ISP.

The argument was that a "slight shortfall" in performance could zero the payload.  A staged-combustion hydrolox engine coming in at 380-400 seconds is not a "slight shortfall".

Hydrolox engine design is much better understood than it was when the 455 s target was established for the SSME, and the design tools are much better.  Furthermore, the SABRE's lower pressure as compared with the SSME would vastly ease the design even if it didn't have hugely more benign turbomachinery environments due to the cycle layout.  Not to mention that the SABRE 4 concentric nozzle design allows the designers to simply ignore sea-level performance and optimize for vacuum; as far as I can tell from the numbers, REL have not attempted to take advantage of this by raising the target Isp.

It would take a 0.7% loss of trajectory-averaged Isp - roughly 3 seconds vac, more than what the SSME saw - just to wipe out the 986 kg performance margin, assuming the vehicle eats up its entire mass growth allowance.  The RS-68 saw a bigger shortfall, but I believe that was because of a known injector design flaw they haven't bothered to fix, and in any case it's still in the range where if SABRE suffered a similar but unfixable shortfall, a reasonable vehicle scale-up could restore the lost payload.

Note also that my numbers so far all assume no vehicle redesign, either to lighten the structure or to replace lost payload with extra propellant.  If you replace lost payload with propellant instead of with nothing (there is headroom in the airframe design), the numbers look even better.

Large reductions in airbreathing effective Isp are perhaps less unlikely, but the design is vastly less sensitive to airbreathing performance (note that Skylon C1 was considered viable even with the SABRE 3, which seems to have had an estimated airbreathing Isp approximately half that of the SABRE 4).  Dry mass could be a problem too, but again my numbers suggest healthy margins, particularly if they're not cheating on the mass growth allowance...

As of two years ago, the SABRE programme was estimated to cost close to $6B, most of that after demonstrating a full-scale prototype on the test stand.  That doesn't sound to me like they plan to just sling together a first cut and call it a day.

I still see no reply to the very informative post of 93143. Any one with better numbers? let's have a polite discussion on how much off the design must be not to deliver. We all want to see the calculations of those claiming the margins are really small.
You need the numbers, the ACTUAL numbers to base such a conversation on. The numbers provided by 93143 are the best estimates available from the estimates and assumptions that REL has done so far which is all well and good. But they are still not actual performance figures.

What?

If we had actual performance figures, there would be no room for said conversation.  The whole point is that we don't; the viability of the design is not known yet and depends on how close they can get to their estimates.  The question is: how much margin for error in those estimates do they have?  If my math is right, it seems they have quite a bit...

Actually there is no business "case" for Skylon because of the simple fact there is no Skylon...

That's not how that works.  You build a business case for something you're considering doing in the future, in order to determine whether or not you should.  If there's no business case for Skylon, no business will build it because it would be a pointless money pit.  The business case comes first; the product comes later.

To be fair, the business case is kinda wobbly right now due partly to the technical unknowns; it should firm up considerably as development progresses (assuming it goes well), which is one reason REL aren't asking for $15B up front...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/11/2016 01:14 am
1) You need the numbers, the ACTUAL numbers to base such a conversation on. The numbers provided by 93143 are the best estimates available from the estimates and assumptions that REL has done so far which is all well and good. But they are still not actual performance figures. If we compare actual, historical numbers... Which was one of the "points" since we can't, no one has designed, built, or operated an SSTO (either horizontal or vertical take off nor by power plant type) so the only available numbers are estimates from previous designs.
True. Hopefully this situation will be clearer by the end of the year.
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2) Everyone has to at least agree on some basic factors to have any chance of discussing the original subject. Which by the way was that "TSTO designs give greater design margins than SSTO designs" which is in fact TRUE and verifiable through historic reference and experience.
Agreed, for VTO ELVs. But the evidence for Shuttle is much less conclusive. Both engine systems failed to meet their performance targets. One did not compensate for the other.
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Despite John Smith 19 confusing "airplanes" with "spacecraft/spaceplanes" and using the old saw that the former are "SSTO" (which ignores SO many operational and design differences as to have no meaning) so "obviously" having the latter SSTO is the only thing that makes sense, and attacks describing all TSTO designs as "failures" of design-and-engineering, etc, etc the basic fact does not change a bit.
Quote
Not so. I think the fact that all other transport systems are "single stage," in the sense they use one vehicle to do one job is strongly suggestive that is the way to go. The reality (until now) is that has not been possible. The question is will it always be so? I don't believe it is a law of nature.
Probably the main question or point of discussion would be how applicable is the SABRE engine design to use on a TSTO vehicle? SABRE on the Skylon is specifically designed for SSTO operations, but we already know from LAPCAT that a similar engine-cycle is applicable to high-speed, in-atmosphere flight so it's not really that much of a stretch to see SABRE being adapted to booster use only even though it is probably less of an efficient use of the system.
Certainly possible. What's odd is why would you would still call it SABRE, given so much of the design would be thrown away?

Logically they should just ask (and pay) REL to design an engine for the part of the flight regime they believe it can safely cover and buy a rocket to cover the rest.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/11/2016 01:15 am
As I understood it they need to test the various components in a basic configuration (hence the "bread-board" type layout) in order to refine the overall design requirements and system functionality. It won't be an "engine" but the systems of the engine run as a unit to define the design of the actual engine.

Just to clarify my position on this.

Testing of various components will progress over the next couple of years and then a "non-flight" proof of concept engine will be tested.
I'm guessing where your post starts and ends as you seem to be having trouble with quoting.

You don't appear to be aware that component design and testing has been underway (funds permitting) since the late 90's

the 2014 NISSIG presentation (http://forum.nasaspaceflight.com/index.php?topic=33648.msg1171426#msg1171426)

Look at slide 15.

You will see they have been developing test components and mfg methods for some time. Not just Powerpoints or CFD models but actual working hardware, at full size wherever possible to avoid scale effects and to allow them to drop that part directly into the full scale engine.

You might like to revise your estimate of how soon that test model will be ready.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 03/11/2016 01:21 am
I think he's talking about the "dissected rabbit" engine, which was ruled out when they got enough money to go full-scale right away but may have been ruled back in when their major investor pulled out, or when BAE bought into the project.  (I can't remember, and right now I should do some actual work instead of digging for that information...)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/11/2016 01:31 am
LOX-LH2 rocketry is a sufficiently mature tech that a large shortfall is ISP seems unlikely, even with the novel pump arrangement.  Which, presuming their engineers have done their jobs right, leaves substantial performance margins before complete loss of payload. 
The design of the SSME was off it's predicted Isp by about 3 secs. Note this was only the 2nd staged combustion engine built in the US and the first (and only) LH2 engine. That's 0.66% for a first of a kind (SC of LH2) design.  This suggests the rocket part at least is fairly well understood.
Not necessarily. Don't exactly know what you mean by "first LH2 engine", probably first LH2 staged combustion engine.
Correct. And you managed to reason that out without using the context of the early part of the sentence IE the first SC engine using storable propellants. This situation will change with the new Blue BE4 engine of course.
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But if you look at the development effort you'll see that it had several years of delays and huge cost overruns in development.
As to hitting the ISP: they had to at all cost to make the whole thing viable, 10s less ISP and there goes your payload.
In total they lost 5 secs across the solid and liquid systems, which lead to a payload "scrub" (of the whole orbiter) to lower mass by 15%. They never achieved the target payload in the payload bay of 65 000lb.

STS demonstrated that any Vertical Takeoff system is very sensitive to Isp
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 03/11/2016 08:22 am
As I understood it they need to test the various components in a basic configuration (hence the "bread-board" type layout) in order to refine the overall design requirements and system functionality. It won't be an "engine" but the systems of the engine run as a unit to define the design of the actual engine.

Just to clarify my position on this.

Testing of various components will progress over the next couple of years and then a "non-flight" proof of concept engine will be tested.
I'm guessing where your post starts and ends as you seem to be having trouble with quoting.

You don't appear to be aware that component design and testing has been underway (funds permitting) since the late 90's

the 2014 NISSIG presentation (http://forum.nasaspaceflight.com/index.php?topic=33648.msg1171426#msg1171426)

Look at slide 15.

You will see they have been developing test components and mfg methods for some time. Not just Powerpoints or CFD models but actual working hardware, at full size wherever possible to avoid scale effects and to allow them to drop that part directly into the full scale engine.

You might like to revise your estimate of how soon that test model will be ready.

The vast majority of Reaction Engines design and testing has been on the heat exchanger.

Although  Detailed design work on all the other components designed for SABRE has been ongoing for some time, I think they now have started to crank up this work, you only have to look at their job adverts over the last 12/18 months to see they now really mean business on a full scale engine development.

One cannot underestimate the task in development. They are developing a joint rocket and jet engine, a world first for the UK again.

While I would love to see a non-flight SABRE on test next year, I cannot see that happening until 2018/2019.
Only time will tell on this JS.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/14/2016 05:58 pm
I still see no reply to the very informative post of 93143. Any one with better numbers? let's have a polite discussion on how much off the design must be not to deliver. We all want to see the calculations of those claiming the margins are really small.
You need the numbers, the ACTUAL numbers to base such a conversation on. The numbers provided by 93143 are the best estimates available from the estimates and assumptions that REL has done so far which is all well and good. But they are still not actual performance figures.

What?

If we had actual performance figures, there would be no room for said conversation.  The whole point is that we don't; the viability of the design is not known yet and depends on how close they can get to their estimates.  The question is: how much margin for error in those estimates do they have?  If my math is right, it seems they have quite a bit...

If their math is correct then your math is probably correct to their estimates... Which still doesn't eliminate the possibility that everyone's math isn't going to be met by actual performance. Doubtful but the chance is non-zero to a significant degree. Hybrid engines specifically are tricky beasts to get working as various SERJ and other air-breathing hybrid engines showed.

But lets' all be honest, what we REALLY want is to but this entire argument to bed for good, which requires the real numbers and yes that would leave LITTLE (come on, you know as well as I do how much people love to argu.... er, discuss this stuff :) ) room for discussion.

Quote
Actually there is no business "case" for Skylon because of the simple fact there is no Skylon...

That's not how that works.  You build a business case for something you're considering doing in the future, in order to determine whether or not you should.  If there's no business case for Skylon, no business will build it because it would be a pointless money pit.  The business case comes first; the product comes later.

To be fair, the business case is kinda wobbly right now due partly to the technical unknowns; it should firm up considerably as development progresses (assuming it goes well), which is one reason REL aren't asking for $15B up front...

To be totally honest the "business case" exists but the Skylon is not technically firm enough to apply to that case. That would be the normal commercial launch business "case" but Skylon isn't at the point yet, (as you note) where it can be realistically compared to the current providers. Skylon IS a "product" under the circumstances and it has to be brought to a point where enough technical and operations unknowns are retired to be able to build an applicable business and operations plan specifically for Skylon.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/14/2016 06:37 pm
1) You need the numbers, the ACTUAL numbers to base such a conversation on. The numbers provided by 93143 are the best estimates available from the estimates and assumptions that REL has done so far which is all well and good. But they are still not actual performance figures. If we compare actual, historical numbers... Which was one of the "points" since we can't, no one has designed, built, or operated an SSTO (either horizontal or vertical take off nor by power plant type) so the only available numbers are estimates from previous designs.
True. Hopefully this situation will be clearer by the end of the year.

Please, yes! :)
 
Quote
Quote
2) Everyone has to at least agree on some basic factors to have any chance of discussing the original subject. Which by the way was that "TSTO designs give greater design margins than SSTO designs" which is in fact TRUE and verifiable through historic reference and experience.
Agreed, for VTO ELVs. But the evidence for Shuttle is much less conclusive. Both engine systems failed to meet their performance targets. One did not compensate for the other.

The Shuttle was specifically a 1.5STO design with the SRBs being "augmentative" rather than an actual stage. It was a design compromise that was well known but un-avoidable under the circumstances. HAD the Shuttle been designed as an actual TSTO or any number of "improved" boosters (and no, the ASRBs were no where near enhance enough to make up for the short-falls) concepts had been built they would have compensated for the SSME short-falls.

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Despite John Smith 19 confusing "airplanes" with "spacecraft/spaceplanes" and using the old saw that the former are "SSTO" (which ignores SO many operational and design differences as to have no meaning) so "obviously" having the latter SSTO is the only thing that makes sense, and attacks describing all TSTO designs as "failures" of design-and-engineering, etc, etc the basic fact does not change a bit.
Not so. I think the fact that all other transport systems are "single stage," in the sense they use one vehicle to do one job is strongly suggestive that is the way to go. The reality (until now) is that has not been possible. The question is will it always be so? I don't believe it is a law of nature.

Quite a few people believe the same way but the plain fact is that no other transportation system has to do what ground-to-orbit transport does and while operationally single-stage has obvious advantages both technically and operationally the minimum we've found to work currently is 1.5STO. If Skylon is fully verified then that could (should) change but there is in fact no guarantee even if Skylon works TECHNICALLY that it won't be OPERATIONALLY as much a game-changer as assumed.

I probably wouldn't go as far as calling it a "law of nature" but pushing payload "uphill" from the surface of the Earth to orbit two-stages sharing the load puts more mass into place than a single stage vehicle does. And those two stages have higher overall margins than the single vehicle can have because they are split between two vehicles.

The main draw/claim for SSTO versus multiple stages in simple terms is that while the SSTO has lower margins and payload to destination, it is cheaper to operate and build since it's only a single vehicle. The idea being that it would be more like all the 'other' transportation systems and therefor even with less payload and possibly a higher cost it could fly more often and OVERALL would deliver more payload and lower operations costs over time. This hasn't been shown yet and is based on a lot of un-proven assumptions based on OTHER transportation systems which don't operate at all like space launch. Will this always apply? Probably not but at this point Skylon is in the same situation as Space Tethers where all the assumed number make them look wonderful but they haven't actually gotten to the point where those numbers are solid enough to assume they are true without significant added assumptions.

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Probably the main question or point of discussion would be how applicable is the SABRE engine design to use on a TSTO vehicle? SABRE on the Skylon is specifically designed for SSTO operations, but we already know from LAPCAT that a similar engine-cycle is applicable to high-speed, in-atmosphere flight so it's not really that much of a stretch to see SABRE being adapted to booster use only even though it is probably less of an efficient use of the system.
Certainly possible. What's odd is why would you would still call it SABRE, given so much of the design would be thrown away?

Logically they should just ask (and pay) REL to design an engine for the part of the flight regime they believe it can safely cover and buy a rocket to cover the rest.  :(

The main point of SABRE is it's a combined air-breather/rocket which means it can cover a larger portion of the trajectory than a single system. You'll note in most combined-cycle studies the AF has had used the first stage to reach speeds low-hypersonic speed (Mach 5-6) and then used rockets to push the stage out of the atmosphere to a point where the second stage needs little or no streamlining and/or the engines can be vacuum optimized.

It would also allow the design to have loiter and significant cross-range launch capability which is another thing the military loves for an "on-demand" launch system.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Radical_Ignorant on 03/15/2016 10:15 pm
Often in this thread there is assumption: if they would go two stage everything would be easier and better. This is reasoning from analogy to VTO rocket Launch Vehicles.
The case is: if they go TTO then nor Skylon nor Sabre has any sense. All concept is build around using air, not fighting with it, what makes it unique and first phase super efficient - and since engines are the same then what you can throw away? Airframe? How much fuel is used in first phase? How much mass could be shaved?
This is two phases to orbit in one stage to orbit.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: QuantumG on 03/15/2016 10:19 pm
A first stage that gets to Mach 5 in the atmosphere, pops over the top of the atmosphere for second stage separation, turns around to return to the launch site, and does a powered landing on a runway. Sounds pretty awesome to me.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Radical_Ignorant on 03/15/2016 10:22 pm
A first stage that gets to Mach 5 in the atmosphere, pops over the top of the atmosphere for second stage separation, turns around to return to the launch site, and does a powered landing on a runway. Sounds pretty awesome to me.

Virgin is pursuing such a concept. Maybe if White Knight could do Mach5... But then look at the shape of White Knight. Anything like that can't do anything near Mach5.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Radical_Ignorant on 03/15/2016 10:53 pm
Unfair treatment of REL.
As few people before I also feel that many here have hostile attitude toward REL.
 They don't have working stuff? That's the very nature of advanced concepts that they are nothing until they are build, because they are not, they do not exist, they are not part of reality. Just what's the reason for looking at advanced concepts If everything is doomed, because you have seen so many failures in the past?
And please keep in mind that in Europe there are nor Elons with 100s millions to throw at their dream (even Branson is building VG, not anything here), nor NASA (ESA is so tiny in comparison), nor DARPA, nor USAF. We even hardly have any VC - so the fact that anything is happening is a miracle in itself :-)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 03/16/2016 12:02 am
Unfair treatment of REL.
As few people before I also feel that many here have hostile attitude toward REL.
 They don't have working stuff? That's the very nature of advanced concepts that they are nothing until they are build, because they are not, they do not exist, they are not part of reality. Just what's the reason for looking at advanced concepts If everything is doomed, because you have seen so many failures in the past?

Or, you could try reading what people are actually saying here.

Nobody is saying everything is doomed.  People are saying it's risky.  People are saying it's riskier to put all the eggs in the single-stage basket and maybe it would be less risky to try a two-stage system first.

I'm not sure how you think people are saying "everything is doomed" from that unless you aren't really interested in what people are actually saying.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Radical_Ignorant on 03/16/2016 07:53 am
  People are saying it's risky.  People are saying it's riskier to put all the eggs in the single-stage basket and maybe it would be less risky to try a two-stage system first.


That is not what I've seen. Of course - I haven't read all the comments, but on last few pages and somewhere on start of this thread5 you were saying making it TS will improve the margins, not that it'll be less risky.

But still - How one vehicle can be more risky than two? Where is more potential points of failure?
What you save in TSTO if first stage fails? How much reputation and value for client you save if only second stage fails?

All I can agree is that it would be more probable if it was smaller and required smaller upfront dev cost. But as few people pointed out, this technology doesn't scale well. Except if they somehow could make it single engine vehicle... Hmm... But then this small vehicle could be like Falcon 1 - rather proof of concept and tech demonstrator than commercial vehicle. Don't know, but I suspect it wouldn't save much development.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 03/16/2016 08:14 am
  People are saying it's risky.  People are saying it's riskier to put all the eggs in the single-stage basket and maybe it would be less risky to try a two-stage system first.


That is not what I've seen. Of course - I haven't read all the comments, but on last few pages and somewhere on start of this thread5 you were saying making it TS will improve the margins, not that it'll be less risky.

But still - How one vehicle can be more risky than two? Where is more potential points of failure?
What you save in TSTO if first stage fails? How much reputation and value for client you save if only second stage fails?

All I can agree is that it would be more probable if it was smaller and required smaller upfront dev cost. But as few people pointed out, this technology doesn't scale well. Except if they somehow could make it single engine vehicle... Hmm... But then this small vehicle could be like Falcon 1 - rather proof of concept and tech demonstrator than commercial vehicle. Don't know, but I suspect it wouldn't save much development.

Could the fact adding a sub scale demonstrator would increase the  already large development costs on their decision to go straight to a full size prototype?.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 03/16/2016 08:19 am
The talk  at the University of Nottingham by Mark Thomas should have happened yesterday (15 March) did anyone go or find any materials about it?


Tonight there seems to be this one in Gloucester:

Quote
The RAeS Gloucester & Cheltenham Branch invite you to explore the history of the aviation industry and learn about the future of space launcher – SKYLON – with Dr Robin Davies, Senior Control and System Engineer of Reaction Engines Ltd.
A Joint Event with the IMechE.


The space launcher industry is still using rocket technology from the 1950s to place things in orbit; it's expensive and involves a new rocket for every launch. SKYLON is an unpiloted, reusable Spaceplane intended to provide reliable, responsive and cost effective access to space. The advanced combined cycle air-breathing SABRE rocket engine enables the vehicle to take off from a runway, fly direct to earth orbit and return for a runway landing, just like an aircraft. This is a game-changing engine technology that could make conventional rockets obsolete overnight!

18:00 visit to Jet Age Museum and networking
19:30 Lecture starts

ALL WELCOME, but please book as spaces are limited.

To book, please email:
Guillermo Durango
[email protected]

For enquiries about the event:
Kerissa Khan
[email protected]


Event address:

Jet Age Museum
Meteor Business Park
Cheltenham Road East
Gloucester
GL2 9QL
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 03/16/2016 08:33 am
  People are saying it's risky.  People are saying it's riskier to put all the eggs in the single-stage basket and maybe it would be less risky to try a two-stage system first.


That is not what I've seen. Of course - I haven't read all the comments, but on last few pages and somewhere on start of this thread5 you were saying making it TS will improve the margins, not that it'll be less risky.

Better margins means less risky.

But still - How one vehicle can be more risky than two? Where is more potential points of failure?
What you save in TSTO if first stage fails? How much reputation and value for client you save if only second stage fails?

I'm talking about design risk here, not the risk of a particular mission -- that is, the risk that the design doesn't pan out and can't carry the intended payload to orbit and/or is too costly.  But, even though it's not what I was talking about, you absolutely can have one vehicle be more risky than two if the one vehicle is pushing the envelope too far.  Instead of spending the margin on getting to orbit in a single stage, you can spend it on making each of the stages simpler and more reliable.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Radical_Ignorant on 03/16/2016 08:41 am

[...] But as few people pointed out, this technology doesn't scale well. Except if they somehow could make it single engine vehicle... Hmm... But then this small vehicle could be like Falcon 1 - rather proof of concept and tech demonstrator than commercial vehicle. Don't know, but I suspect it wouldn't save much development.

Could the fact adding a sub scale demonstrator would increase the  already large development costs on their decision to go straight to a full size prototype?.

Not sure. IMHO Skylon is "power-point vehicle" at the moment. Sabre is an engine in development which will allow something Skylonish to happen, and maybe as well something very unskylonish as well. Diesel engine happened for cars but allowed big changes in maritime/rails.
Single engine vehicle would not change a bit in next few years of development. And having more possibilities, like vision for small 5humans to orbit cheaper vehicle would maybe help to find founds.
However that's far from their focus - they want to develop engine, not vehicle, so it's very little chance they will take resources from engine development to investigate such a case. But it doesn't make it stupid/wrong/impossible.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 03/16/2016 08:45 am
I suppose it's a vain hope that there will be anything in today's budget for REL.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Radical_Ignorant on 03/16/2016 09:01 am
  People are saying it's risky.  People are saying it's riskier to put all the eggs in the single-stage basket and maybe it would be less risky to try a two-stage system first.


That is not what I've seen. Of course - I haven't read all the comments, but on last few pages and somewhere on start of this thread5 you were saying making it TS will improve the margins, not that it'll be less risky.

Better margins means less risky.


Payload margins is wasted opportunity and means lost income.
Better financial margins means ULA against Space X way, not sure if that's always better.
It's all about trade offs.

Finally as far as I understand whole concept, making it two stage is just over complication which does not help as far as LEO is considered. Then they are talking about thugs for GEO, rockets for BEO - so you have your second stage.

All benefits of Sabre disappear if you have to carry engine which is not used for bigger part of the way. I think you are still reasoning by analogy. First leg of the journey is not as hard as in VTOL rocket in any way. You don't need so powerful engines, you don't need so much fuel. So stage separation becomes much less attractive. That's the very core of Sabre/Skylon concept. Like not having a sail on steam boat.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Radical_Ignorant on 03/16/2016 09:18 am

But still - How one vehicle can be more risky than two? Where is more potential points of failure?
What you save in TSTO if first stage fails? How much reputation and value for client you save if only second stage fails?

I'm talking about design risk here, not the risk of a particular mission -- that is, the risk that the design doesn't pan out and can't carry the intended payload to orbit and/or is too costly.  But, even though it's not what I was talking about, you absolutely can have one vehicle be more risky than two if the one vehicle is pushing the envelope too far.  Instead of spending the margin on getting to orbit in a single stage, you can spend it on making each of the stages simpler and more reliable.

That is a point. How far and how do we want envelope to be pushed. If you push it to little you have nothing new and your efforts are not providing any benefit.
If you push to far into unknown territory all becomes just research. But then to quote them "we have all research done, what's left is development not research" - so they aren't pushing envelope into unknown territory.
Maybe I'm dumb but it seems simple. If Sabre works, then there is nothing very risky in Skylon. If Sabre does not work, then no matter number the stages or scale it makes no sense. And unfortunately Sabre is not very scalable. Nor down (engine reasons) nor up (infrastructure reasons) except single engine possibility.
But I got off. In short if you don't push envelope you don't have benefits. You much prefer Space X way of pushing it in small steps. But then we have Space X and they won't stop doing it, so duplicating their way is doing what other does and makes no sense if you are not established player on the market.
 Can you go to investors and tell them: hey I need few hundred millions and I'll do things like Space X is doing except I'm much late into the game and don't have experience and hmmm, here in Europe I can't count on NASA, DOD, USAF contracts?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 03/16/2016 09:38 am
I have found some tweets from the talk at the University of Nottingham:

https://twitter.com/search?q=sabre%20reactionengines&src=typd

Some samples (Most from a gentleman called Jon Knight):
Quote
#sabre engine flight demonstration aimed for 2023-2025, with production in following decade. Are @ReactionEngines going to be too late?

Question asked about @ReactionEngines finances. They see #sabre and heat exchange tech as they income generators.

Mark Thomas: Since @BAESystemsInc investment @ReactionEngines has scaled up and improved manufacturing processes further #SABRE

There is a schools competition between @ReactionEngines and iMechE to design a #Sabre powered transport aircraft for RAF.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 03/16/2016 10:49 am
...And unfortunately Sabre is not very scalable. Nor down (engine reasons) nor up (infrastructure reasons) except single engine possibility.

You have mentioned "single engine possibility" more than once now.

It should be pointed out that it was the rear-heavy design failure of HOTOL - which became a "means for lifting hydraulics into orbit" (huge canards to compensate CoM issues) - which principally drove the twin-engined Skylon design.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 03/16/2016 12:29 pm

Payload margins is wasted opportunity and means lost income.


Wrong.  They are not talking about payload margins for a specific launch, but development margins.  You design for X + 20% capability, so that as issues and things like weight creep and ISP/thrust losses come around, you can still hit your target X capability.   TS means better development margins.

Shuttle has a problem because of margins.  Mass to orbit was not just the payload at 50klb (round numbers) but the 250klb orbiter.  So if the orbiter came in too heavy at 5%, that means the payload loses 12.5klb mass.  that is why they had to increase the performance of the system.  For SSTO, it is worse.

Also, most payload use the whole capability of current vehicles.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: TrevorMonty on 03/16/2016 03:24 pm
A strapon booster for existing/future LV is one possibility.

Does anybody know what type performance increase 2 1xsabre boosters would give Vulcan assuming they separate at Mach5.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 03/16/2016 04:07 pm
People are saying it's riskier to put all the eggs in the single-stage basket and maybe it would be less risky to try a two-stage system first.
you were saying making it TS will improve the margins, not that it'll be less risky.
Better margins means less risky.
Payload margins is wasted opportunity and means lost income.

Engineering margins.

That might be the difference between designing for 700 degrees, versus 1200 degrees. Between using machine stamped aluminium, versus hand-made carbon-composite. Between a component lasting a hundred hours, versus just ten hours. Between a modular assembly that can be quickly swapped out, versus deeply integrated components that require thousands of hours of disassembly to change one part. Between being able to use lower cost mass-produced off-the-shelf components for mundane elements, versus having to design and customise every single part in low-volume production.

There's an old engineering rule-of-thumb that each 10% increase in material, doubles the life of the part. Probably the same with cost. Things don't scale linearly, there's an exponent in the curve.

And that feeds back into every other assumption in your business case. Cost of development, cost of operations, lifespan of vehicles, turn-around time of vehicles.

But still - How one vehicle can be more risky than two?

Because the one and the two are not the same types of vehicles.

Two trucks are clearly easier to develop than one jet. The engineering challenge of developing an SSTO is so astoundingly far beyond the engineering challenge of TSTO. Not just twice as hard, but orders of magnitude.

proof of concept and tech demonstrator [...] but I suspect it wouldn't save much development.

This is, IMO, one of the most destructive myths in aerospace. The belief that developing directly to the end goal is going to be cheaper than passing through three or four operational stepping-stones.

Reality is the opposite. Unless what you are developing is completely mundane and your designers, engineers, technicians and ops people are all experienced in that technology, it will always cost less to pass through multiple iterative stages before even attempting the final design. (Indeed, before attempting to design the final design.)

(It's the same "one is less than two" mentality.)

REL is at least doing one form of iterative development: subscale component testing. It also seems like they are happy to have other players use their technology on lower risk iterations, ironically unlike many of their defenders here.

In short if you don't push envelope you don't have benefits. You much prefer Space X way of pushing it in small steps. But then we have Space X and they won't stop doing it, so duplicating their way is doing what other does and makes no sense if you are not established player on the market.

That's silly. It's their method you'd be copying, iterative development, not the product.

Can you go to investors and tell them: hey I need few hundred millions and I'll do things like Space X is doing except I'm much late into the game

Versus going to investors and saying: hey I need a ten billion (probably) and I'll (try to) develop something that no-one (including me) has ever done before, and without doing any risk-reducing steps? Oh, and because I'm developing directly to the end-goal, you won't see any return for twenty years. Oh, and it involves sustained high-mach flight, which has been traditionally horribly expensive. Oh, and it involves a hybrid engine, which has traditionally been horribly expensive. Oh, and we're not airframe designers, so we'll need to outsource that anyway, but don't worry, this computer model says my design is perfect.

[edit: typos]
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 03/16/2016 04:21 pm
A strapon booster for existing/future LV is one possibility.
Does anybody know what type performance increase 2 1xsabre boosters would give Vulcan assuming they separate at Mach5.

SABRE has a projected thrust-to-weight ratio of around 14. That's double the F119 engine, for example, which itself it higher than most commercial engines.

But rocket engines are up around 80-100. (The record is either Merlin 1D (180:1) or one of the Russian engines.)

[edit2: to clarify that. It means that if your SABRE-booster and fuel masses 14 times the mass of the engine, the booster will only be able to hover, it won't add any lift. If it masses more than 14 times the engine, the boosters will actually be hanging off the core stage, merely adding to the weight.]

SABRE's Isp is massively better than any rocket during its air-breathing mode, but for a vertical launch that precisely when you are most willing to sacrifice Isp for thrust. (The amount of fuel you burn in your first three minutes is much less important than the amount consumed in the last three minutes, because the fuel burnt in the last three minutes has to be carried during the rest of the flight.)

Skylon can cope with low thrust/weight because it gets lift from aerodynamic surfaces to compensate for gravity losses. And that long horizontal climb is where you need high-Isp.

[edit1: added the parenthesised comments]
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/16/2016 07:11 pm
You have mentioned "single engine possibility" more than once now.

It should be pointed out that it was the rear-heavy design failure of HOTOL - which became a "means for lifting hydraulics into orbit" (huge canards to compensate CoM issues) - which principally drove the twin-engined Skylon design.
True.

For a demonstration vehicle what is essentially a winged nacelle would be possible.

To preserve the CoG protecting features you'd need to put it on top of the payload bay, like a sort of V1 cruise missile.

But that would leave the issue of how  you open the bay to get the payload out. 

The latter is a slightly closer to Skylon so might shorten the test programme of the real Skylon, while the former is likely to be cheaper.

Both would probably make the test programme more expensive overall.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/16/2016 07:21 pm
A strapon booster for existing/future LV is one possibility.
No it's not. This was a running theme of WIlliam Escher.  It's a bad notion given the poor T/W of airbreathers (although SABRE's is excellent by turbofan standards).

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/16/2016 07:42 pm
It would also allow the design to have loiter and significant cross-range launch capability which is another thing the military loves for an "on-demand" launch system.
The cross range capability is a result of the Skylon design, not the SABRE engine.

But a pre cooled engine gives you the T/W to allow such a design to take off from a runway.

It took me years to find a report that would finally state what a SCRamjet T/W was.  ONce I saw "2:1" It thought, "how did they ever get funding to pursue this?" Yet $Bn have been spent.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/16/2016 09:12 pm
Often in this thread there is assumption: if they would go two stage everything would be easier and better. This is reasoning from analogy to VTO rocket Launch Vehicles.
The case is: if they go TTO then nor Skylon nor Sabre has any sense. All concept is build around using air, not fighting with it, what makes it unique and first phase super efficient - and since engines are the same then what you can throw away? Airframe? How much fuel is used in first phase? How much mass could be shaved?
This is two phases to orbit in one stage to orbit.

Right off the bat let me say that there have been a LOT of combined cycle rocket-air-breathing engine concepts over the years that have performance similar to the SABRE and they have been suggested for use in booster stages of a TSTO system NOT because they can't fly all the way to orbit but because a TSTO system nominally has more payload and engineering margins than an SSTO. The concept and practice of "using" the air and not "fighting" it is a well known possible path of development for spaceflight. (Trust me, this is one I've argued for years :) ) In reality though they have never been as simple as just using all rockets despite any obvious disadvantages and the real struggle is to get any of them to an operational or demonstrable flying status in order to actually PROVE the advantages. Skylon/SABRE is no different really and must ("justifiable" or not) therefor prove itself and it's advantages.

The "case" is a lot more complex than you make it out to be. First of all there is a difference between "orbit" and "destination" that is often ignored in these comparisons. Far more often than not the former is not the latter. The adage that once you're in orbit you are half way to anywhere is often cited as a truism but really we don't currently USE LEO as much as that was assumed when that was said. GTO/GEO and escape trajectories, serviced by multi-stage, direct ascent vehicles has become the default method instead of LEO rendezvous, fueling, and orbital assembly. The latter is more conducive to SSTO operations because SSTOs rarely can service both systems while TSTOs have the excess capability to do so. Skylon does not change this operational fact. (See below)

Second your assumed "assumption" is not correct as the reason the analogy of current VTO TSTO is used for comparison is that they exist and the data is well known. Similar comparisons have been done with just about every proposed concept for getting from the surface to orbit because that data is so well known and available and Skylon is not any special case. Lastly the suggestion, (not assumption) is that a TSTO system would have higher engineering margins and payload mass than an SSTO system FOR THE SAME DESIGN POINTS. Which is admittedly something that tends to get forgotten in the conversation.

Why do you assume at all that something must be "thrown away"? Staging is dropping off excess mass to increase efficiency of the overall system. That CAN mean "expending" some portion of the system, (which isn't either 'bad' nor unheard of since every transportation system 'expends' fuel to operate after all :) ) and there are viable and logical trade-offs where that may apply, but dropping off the excess mass of the booster stage and continuing the mission profile with a more efficient second stage that is fully reusable is as valid an assumption as not.

And in fact operationally the Skylon is a two stage 'to-destination' vehicle with the Skylon only attaining orbit while it requires a second stage, (Skylon Upper Stage, SUS) to deliver it's designed payload to the proper (GTO/GEO) orbit or beyond. (This tends to be where the statement that the Skylon was designed to carry "EELV" class payloads breaks down. In general that payload class is somewhere between 8mt to 10mt to GTO, but closer to 18mt to 20mt to LEO. Best case for Skylon is between 15mt and 18mt to LEO and that has to include the SUS mass for GTO/GEO payloads) The SUS can be used either as an expendable or reusable stage depending on the payload destination requirements. You'll note the various payload capabilities listed in the Skylon Users Manual and various propulsive requirements for each*

REL decided on going SSTO rather than TSTO for reasons they have often given HOWEVER that in no way invalidates the use of the SABRE in TSTO applications nor do any of those reasons REL gives do so.

I keep pointing out that SABRE is perfectly capable of performing the most common HTL air-breathing booster mission; Ground take-off, Orbital plane and Trajectory adjustment or "cruise" mode to selected "launch" point, "launch" with acceleration to above Mach-5 in air-breathing mode, powered pull-up and switching to pure rocket mode for climb outside the atmosphere, release second stage, perform controlled reentry and powered return to take off site for turn around. REL has base lined the Skylon as an SSTO vehicle and operations mode but even they admit that TSTO operations even with the Skylon design has operational and payload advantages. It would be more advantageous if the Skylon were actually designed for the TSTO booster role but that's not the way they are aiming and the reasons given are viable either way for the assumptions made.

AFRL has been looking at both SSTO and TSTO designs using various propulsion systems and for various applications for decades and they are interested in the SABRE as a power plant for an HTL-TSTO booster application which, while different operationally from the path that REL chose it's no less valid and it certainly can't be argued as being 'wrong' either. Frankly, if they can keep from trying to slap some SCRamjets on the design somewhere it has a much higher chance of reaching testing which would benefit REL to no end than if REL had insisted that the SABRE can ONLY be used on SSTO designs and crocked the whole deal. REL doesn't have an issue with the decision really, so why should we?

Randy
*REL itself, while rightly pointing out that the Skylon is DESIGNED for SSTO operations and is more "efficient" at that design point given it's design assumptions, explains that the Skylon AS DESIGNED is capable of and could be used as the suborbital first stage of a two-stage mission. It's right there in the Skylon Users Manual cited earlier. Page 8-9 give orbital figures while page 10 is for suborbital deployment. Note in either case for anything other than LEO all payloads have to include propulsion to deliver to their required destination. As noted above that's somewhere around 15mt to 18mt for Skylon delivery to orbit but the guide points out that Skylon can deliver up to it's maximum STRUCTURAL load of 30mt in a suborbital, two stage launch with payload supplied propulsion.  :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/16/2016 09:23 pm
You have mentioned "single engine possibility" more than once now.

It should be pointed out that it was the rear-heavy design failure of HOTOL - which became a "means for lifting hydraulics into orbit" (huge canards to compensate CoM issues) - which principally drove the twin-engined Skylon design.
True.

For a demonstration vehicle what is essentially a winged nacelle would be possible.

To preserve the CoG protecting features you'd need to put it on top of the payload bay, like a sort of V1 cruise missile.

But that would leave the issue of how  you open the bay to get the payload out. 

The latter is a slightly closer to Skylon so might shorten the test programme of the real Skylon, while the former is likely to be cheaper.

Both would probably make the test programme more expensive overall.

Two things; While it's awkward, "under" is also possible, but more importantly would you want a 'demonstrator' to have payload? It's nice but... You could also go with a more integrated engine/body design which REL has avoided due to this being rather difficult to get "just right" without extensive testing BUT it something that any airframe manufacturer could do within a budget. The basic Skylon design is the way it is to avoid as much airframe design work as possible, (REL keeps telling everyone they design engines with airframes as a side-line to have something to put those engines on after all :) ) but once you go beyond that requirement there's a lot of ways to do the design itself.

In the end you have to make a decision what exactly the 'demonstrator' is demonstrating. If it's engine operations over the flight regime an actual payload isn't needed. If it's going to be demonstrating that the entire concept of both the engine cycle flight operations is possible then you are pretty much designing a actual sub-scale vehicle with certain capabilities which can include payload deployment. (This was the concept behind the GTX which could "deliver" 300kg to orbit or carry test instruments, but was also to demonstrate the engine concept) There are variations in between but not as much as you'd think.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 03/16/2016 09:31 pm
Shuttle has a problem because of margins.  Mass to orbit was not just the payload at 50klb (round numbers) but the 250klb orbiter.  So if the orbiter came in too heavy at 5%, that means the payload loses 12.5klb mass.  that is why they had to increase the performance of the system.  For SSTO, it is worse.

Not this SSTO.  The vehicle's projected mass at MECO minus the payload is less than four times the payload, not much worse than the Shuttle orbiter and significantly better than the orbiter+ET.  This is after industry-standard mass growth margins.

The engineering challenge of developing an SSTO is so astoundingly far beyond the engineering challenge of TSTO. Not just twice as hard, but orders of magnitude.

The whole point of SABRE is that it makes this not true any more.  Insisting otherwise without any actual math as backup (as people like to pop in here and do now and then) is cargo cultism - associating the difficulty with the label rather than with the technological requirements.

Quote
REL is at least doing one form of iterative development: subscale component testing. It also seems like they are happy to have other players use their technology on lower risk iterations, ironically unlike many of their defenders here.

Quite so.  But they apparently see no need to take that detour themselves; they've been doing risk reduction on the SSTO and pushing it pretty much exclusively, because they think it's a reasonable thing to do if the engine works.

The technical risk involved in doing TSTO first is probably lower.  But the cost may very well not be - these are still high-performance flight vehicles, after all - and the commercial payoff is dubious.

Quote
Engineering margins.

Last I heard, the airframe was being designed to a safety factor of 1.5, the same as a commercial airliner.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/16/2016 09:41 pm
A strapon booster for existing/future LV is one possibility.
No it's not. This was a running theme of WIlliam Escher.  It's a bad notion given the poor T/W of airbreathers (although SABRE's is excellent by turbofan standards).

Oh it's still possible, just not likely :) T/W can be adjusted in a lot of jet engines by various means. Some more operationally viable than others, but in context you could get a much higher T/W from the SABRE with enough work. The main issue is why you'd want to though as it would degrade capability in other areas enough that it probably wouldn't be a SABRE anymore.
And it should be pointed out that he did say "future" LVs too which could be interesting to explore. The main issue with current LVs is they don't deal well with horizontal operations and you'd avoid VTO operations with the base line SABRE so what if any advantage would there be?

It would also allow the design to have loiter and significant cross-range launch capability which is another thing the military loves for an "on-demand" launch system.
The cross range capability is a result of the Skylon design, not the SABRE engine.

Really? What's the cross-range on an Atlas-V or Delta-IV? :)

No that's actually because the SABRE is an air-breathing engine which allows them to MOVE the launch point around to where they need it. I probably should have been more explicit though.

Quote
But a pre cooled engine gives you the T/W to allow such a design to take off from a runway.

You and I have discussed this before and it's NOT just pre-cooling that allows such operations. The SERJ could do it just fine without. With enough "bits" added, (pre-cooling was included in all of Escher's "Spaceliner" class air-breathing propulsion engines except some H2O2 prototype design concepts) you get a T/W which allows VTOL operations which was unattainable for most jet-type engines alone. No where near a rockets but a lot of the combined cycle engines used both rockets and air-breathing in various combinations in the same engine anyway.

It's a design toss-up decision that is based on what your assumptions are from the start. Frankly I don't see SABRE working that way operationally efficient enough to warrant and would stick to HTOL operations to take advantage of the cycle.

Quote
It took me years to find a report that would finally state what a SCRamjet T/W was.  ONce I saw "2:1" It thought, "how did they ever get funding to pursue this?" Yet $Bn have been spent.  :(

But EVENTUALLY (so the theory says) you can go as fast as you want to with a SCRamjet engine which is WHY the bucks keep flowing in. Of course as everyone well knows "I" can't see any way that justifies trying to fly around in an atmosphere at speeds above Mach-5 for any length of time but then again I'm not an advocate of SCRamjets anyway :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 03/16/2016 10:57 pm


Quote
Engineering margins.

Last I heard, the airframe was being designed to a safety factor of 1.5, the same as a commercial airliner.

That is not the same.  Engineering or design margin is in addition to the safety factor. If they design has something wrong or under calculated, they might not have 1.5 safety factor
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 03/16/2016 10:59 pm
Shuttle has a problem because of margins.  Mass to orbit was not just the payload at 50klb (round numbers) but the 250klb orbiter.  So if the orbiter came in too heavy at 5%, that means the payload loses 12.5klb mass.  that is why they had to increase the performance of the system.  For SSTO, it is worse.
Not this SSTO. 

Yes, this SSTO and all others.  They are more sensitive to mass increases than other LVs, especially first stages.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 03/17/2016 01:08 am
Engineering or design margin is in addition to the safety factor. If they design has something wrong or under calculated, they might not have 1.5 safety factor

I may have trimmed my post too much.  In any case it doesn't sound like the post I was responding to meant anything especially specific by the term...

REL claims (http://iafastro.directory/iac/archive/browse/IAC-10/D2/4/7325/) that Skylon D1 uses "a mass margin philosophy consistent with AIAA guidelines", and one of their old papers (http://reactionengines.co.uk/tech_docs/JBIS_v57_x-x.pdf) calculated C1's truss structure mass using both a safety factor of 1.5 and a 15% mass growth allowance.  They're not just using bare calculated part masses in their presentations.  And there's a modest payload margin (~6.5% as of two years ago) on top of the structural margins.

Yes, this SSTO and all others.  They are more sensitive to mass increases than other LVs, especially first stages.

The point wasn't about "other LVs", and nobody mentioned first stages.  You were taking STS as an example, noting that the bulk of the mass that had to make orbit was not payload, and then said that "For SSTO, it is worse".

Well, technically this one is, a little, if you only compare it to the orbiter.  But a better comparison might be to the orbiter+ET, since that's the hardware unit that reaches orbit (basically) and thus trades 1:1 with payload.  It's also a better functional match to Skylon.  And it turns out that the payload of Skylon D1 (15,000 kg) is a larger fraction of the projected total orbited mass (73,435 kg) than the payload of STS was if you include the ET.  Even if you don't, it's fairly close.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: TrevorMonty on 03/17/2016 01:24 am
A strapon booster for existing/future LV is one possibility.
Does anybody know what type performance increase 2 1xsabre boosters would give Vulcan assuming they separate at Mach5.

SABRE has a projected thrust-to-weight ratio of around 14. That's double the F119 engine, for example, which itself it higher than most commercial engines.

But rocket engines are up around 80-100. (The record is either Merlin 1D (180:1) or one of the Russian engines.)

[edit2: to clarify that. It means that if your SABRE-booster and fuel masses 14 times the mass of the engine, the booster will only be able to hover, it won't add any lift. If it masses more than 14 times the engine, the boosters will actually be hanging off the core stage, merely adding to the weight.]

SABRE's Isp is massively better than any rocket during its air-breathing mode, but for a vertical launch that precisely when you are most willing to sacrifice Isp for thrust. (The amount of fuel you burn in your first three minutes is much less important than the amount consumed in the last three minutes, because the fuel burnt in the last three minutes has to be carried during the rest of the flight.)

Skylon can cope with low thrust/weight because it gets lift from aerodynamic surfaces to compensate for gravity losses. And that long horizontal climb is where you need high-Isp.

[edit1: added the parenthesised comments]
Figured where I went wrong, I was looking at its rocket phase (LoX/LH) thrust of 440lkbs not airbreathing thrust which is considerably less.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 03/17/2016 03:11 am
To preserve the CoG protecting features you'd need to put it on top of the payload bay, like a sort of V1 cruise missile.
But that would leave the issue of how  you open the bay to get the payload out.

Belly doors, obviously. (Loading would be via an elevator-pit.)

but dropping off the excess mass of the booster stage and continuing the mission profile with a more efficient second stage that is fully reusable is as valid an assumption as not.

If you're using SABRE, then you've got that backwards. You'd have a reusable first stage (the Skylon-derivative), with an expendable all-rocket, vacuum-optimised upper-stage.

The cross range capability is a result of the Skylon design, not the SABRE engine.
No that's actually because the SABRE is an air-breathing engine which allows them to MOVE the launch point around to where they need it.

JS19's point was that any air-launch system has the same cross-range, rapid deployment ability; not just a SABRE-based launcher.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hanelyp on 03/17/2016 03:57 pm
If you use a Skylon derived first stage in a TSTO system, the second stage would be all rocket vacuum optimized, not necessarily expendable.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 03/17/2016 05:16 pm
To preserve the CoG protecting features you'd need to put it on top of the payload bay, like a sort of V1 cruise missile.
But that would leave the issue of how  you open the bay to get the payload out.

Belly doors, obviously. (Loading would be via an elevator-pit.)

Bear in mind that even with the SABREs on the wingtips there's concern over the vacuum-expanded plume heating the rear fuselage. So a V1-style configuration could melt the aft?

If you really need a single SABRE config, then perhaps something D21-like could work? You'd have to run the cooled air around or through the tanks, and managing center of mass would be trickier. You might need the same dual LOX and H2 tanks that Skylon has in order to be able to drain fore/aft strategically. Sounds like too many compromises vs. the standard Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Vultur on 03/17/2016 05:36 pm
The engineering challenge of developing an SSTO is so astoundingly far beyond the engineering challenge of TSTO. Not just twice as hard, but orders of magnitude.

The whole point of SABRE is that it makes this not true any more.  Insisting otherwise without any actual math as backup (as people like to pop in here and do now and then) is cargo cultism - associating the difficulty with the label rather than with the technological requirements.

I'm not sure this is even true of pure-rocket SSTOs anymore, and I'm pretty sure it won't be in 5 years.

SSTO-level mass fractions have been done before. SpaceX has demonstrated engines with sufficient TWR, and they're working on VTVL recovery and reusability. In 5 years, they should have the capacities needed to build a pure-rocket VTVL SSTO (they won't, because it doesn't fit their plans, but they could).

A pure-rocket SSTO would still have less payload than a TSTO, and would be harder, but not I think orders of magnitude harder.

EDIT:
The "case" is a lot more complex than you make it out to be. First of all there is a difference between "orbit" and "destination" that is often ignored in these comparisons. Far more often than not the former is not the latter. The adage that once you're in orbit you are half way to anywhere is often cited as a truism but really we don't currently USE LEO as much as that was assumed when that was said. GTO/GEO and escape trajectories, serviced by multi-stage, direct ascent vehicles has become the default method instead of LEO rendezvous, fueling, and orbital assembly.

True. I think SSTOs would have a much stronger case if we had space tugs.

However, with electric propulsion now being available to raise satellite orbits...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 03/18/2016 01:10 pm
video from SABRE – The Next Leap Forward in Powered Flight (http://tinyurl.com/SABRErecording)
15th March 2016, Aerospace and Transport Technologies Research Priority Area, Faculty of Engineering, Nottingham University.

(I've not seen it yet, but passing on the link)

Almost inaudible - a shame...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 03/18/2016 01:56 pm
The audio has had a strong noise-gate filter applied, so the gaps between words are dropped to low volume. I bet it would be easier to understand if that were removed - assuming it's not in the original recording.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/18/2016 07:45 pm
Belly doors, obviously. (Loading would be via an elevator-pit.)
I had not thought of this. More or less SOP for bombers though.
Quote
If you're using SABRE, then you've got that backwards. You'd have a reusable first stage (the Skylon-derivative), with an expendable all-rocket, vacuum-optimised upper-stage.
Yes that makes more sense. The days when avionics was so heavy/expensive to only use 1 set is long over.
Quote
JS19's point was that any air-launch system has the same cross-range, rapid deployment ability; not just a SABRE-based launcher.
Not quite. In principal you could get the cross range on a Skylon shaped vehicle with rockets, because Skylons aerodynamics are better than the Shuttle (not having slab sides on your fuselage is probably quite helpful here), but you'd take a big hit on payload because of the extra reaction mass that vehicle would take which SABRE gets from the air.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 03/18/2016 08:32 pm
If anyone from REL reads this.....please please provide some advertising of the talks you're going to give in advance - e.g. a list on your website.  Quite a few people mentioned this to me recently and it is *the* most basic form of public relations you could engage in.  I mean giving the talk itself is many times harder than entering an item onto an REL web page so what's the problem?

Another issue is please consider recording the audio for these things. again this is not so hard with modern technology - a mobile phone with an external battery would make the whole thing easy and reliable - it can sit on the presenter's desk or in their pocket. 

Think how you manage to talk to 50 people in a lecture theatre but 100s or 1000s over a period of months on the internet. Of all those people the number that can help you is small so you have to maximise the reach of each chance you get to state your case. Some of us are such fools we want to spend our spare time helping you so help us please.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Radical_Ignorant on 03/19/2016 07:34 am
...And unfortunately Sabre is not very scalable. Nor down (engine reasons) nor up (infrastructure reasons) except single engine possibility.

You have mentioned "single engine possibility" more than once now.

It should be pointed out that it was the rear-heavy design failure of HOTOL - which became a "means for lifting hydraulics into orbit" (huge canards to compensate CoM issues) - which principally drove the twin-engined Skylon design.

Yes. I'm fully aware of this. I just think Skylon idea for them is more like basic math which proves: yes, this makes sense, so let's not waste time wondering what could be done if engines were ready. We now know something very useful can be done so let's focus our super tiny resources on engine development.
But there is lot of different shapes of working planes. I won't pretend I know anything about aerodynamics, but I believe if they were bigger and have time to focus a little bit on anything else than engine development, they, or other air frame developers, could came with other solutions. Maybe this one is optimal, but those others could be little more expensive per kg of cargo delivered while much cheaper per vehicle.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Radical_Ignorant on 03/19/2016 08:20 am

proof of concept and tech demonstrator [...] but I suspect it wouldn't save much development.

This is, IMO, one of the most destructive myths in aerospace. The belief that developing directly to the end goal is going to be cheaper than passing through three or four operational stepping-stones.

Reality is the opposite. Unless what you are developing is completely mundane and your designers, engineers, technicians and ops people are all experienced in that technology, it will always cost less to pass through multiple iterative stages before even attempting the final design. (Indeed, before attempting to design the final design.)

(It's the same "one is less than two" mentality.)

REL is at least doing one form of iterative development: subscale component testing. It also seems like they are happy to have other players use their technology on lower risk iterations, ironically unlike many of their defenders here.

In short if you don't push envelope you don't have benefits. You much prefer Space X way of pushing it in small steps. But then we have Space X and they won't stop doing it, so duplicating their way is doing what other does and makes no sense if you are not established player on the market.

That's silly. It's their method you'd be copying, iterative development, not the product.

Can you go to investors and tell them: hey I need few hundred millions and I'll do things like Space X is doing except I'm much late into the game

Versus going to investors and saying: hey I need a ten billion (probably) and I'll (try to) develop something that no-one (including me) has ever done before, and without doing any risk-reducing steps? Oh, and because I'm developing directly to the end-goal, you won't see any return for twenty years. Oh, and it involves sustained high-mach flight, which has been traditionally horribly expensive. Oh, and it involves a hybrid engine, which has traditionally been horribly expensive. Oh, and we're not airframe designers, so we'll need to outsource that anyway, but don't worry, this computer model says my design is perfect.

[edit: typos]

I believe here you nailed core point of our disagreement. But first - please don't suggest that I'm against risk reducing steps. I'm aware it can fail, I'm aware of costs.
Please consider that in Europe there is no something like NASA or DARPA which will pay for tech demonstrators. So you'd need to have some private willing to pay for most of development for something not usable. I just can't imagine such a thing. That's the very reason why you have those gov agencies. We don't have them.
Secondly, there is what Zurbin is arguing against: let's do multiple middle steps. Let's push the final goal so far away that till this time will come, everything will change. How many projects with approach let's-first-develop-demonstrator were never continued because of, "nah, we are not interested in this anymore" from politicians.
However I think I now understand much better your point. Shuttle seems to be good example of rushed development which failed in most of goals because it was first iteration of new technology. So thanks for making your stance clearer for me.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 03/19/2016 11:43 am
Please consider that in Europe there is no something like NASA or DARPA which will pay for tech demonstrators.

That's precisely why trying to jump directly to a multi-billion Pound/Euro design seems so unlikely.

And I'm not talking about "tech demonstrators", I'm talking about productive versions that reduce the development costs for each step.

Secondly, there is what Zurbin is arguing against: let's do multiple middle steps. Let's push the final goal so far away that till this time will come, everything will change.

How's that worked out for Zubrin so far? He's now notorious for handwaving any problems in his own proposals while attacking any alternatives, to the point that I doubt anyone except a few rusted-on amazing people¹ take him at all seriously any more.

The most he's achieved is to reduce support for other technology development programs.

¹ Of course, one of those amazing people now owns his own rocket company. But ironically he practices the iterative development method I prefer.

How many projects with approach let's-first-develop-demonstrator were never continued because of, "nah, we are not interested in this anymore" from politicians.

Far fewer than have overpromised and underdelivered, and consumed way too much money chasing a technological mirage before being cancelled.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: alanr74 on 03/19/2016 11:59 am
not sure if this is useful, but I snipped the slides from the talk.

https://imgur.com/a/F87pA
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 03/19/2016 12:11 pm
I wish someone had asked about nozzle development and whether they've decided to go for ED nozzle's or not. And if not, what were the factors underlying the decision.

Also: from listening to the talk I got the impression that Mark Thomas (&REL) was moving away from trying to develop the skylon design (due to commercial/funding realities) and looking more to develop and prove the engine tech first. Maybe along the lines as suggested by AFRL. Anyone else get that impression, or just me reading too much into his voice and intonation on the point.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: alanr74 on 03/19/2016 12:26 pm
I wish someone had asked about nozzle development and whether they've decided to go for ED nozzle's or not. And if not, what were the factors underlying the decision.

Also: from listening to the talk I got the impression that Mark Thomas (&REL) was moving away from trying to develop the skylon design (due to commercial/funding realities) and looking more to develop and prove the engine tech first. Maybe along the lines as suggested by AFRL. Anyone else get that impression, or just me reading too much into his voice and intonation on the point.

I don't think they've ever been interested in the manufacture of the actual spaceplane (are they called space planes?). It's always been about the engine as to build the actual spaceplane and the engine would be something that is just not feasible.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 03/19/2016 01:38 pm
@alanr74
Yes, but they've always actively promoted the Skylon idea, even going through iterations of designs for the craft. They've said that Skylon was the optimal configuration for the Sabre engine. That's above and beyond just designing an engine.

At least that's been my impression of the story thus far. Every presentation they gave always heavily featured Skylon. My impression from this talk was that, although Skylon would be great, Mark Thomas seemed to be more open to other developmental pathways first.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 03/19/2016 05:56 pm
...
At least that's been my impression of the story thus far. Every presentation they gave always heavily featured Skylon. My impression from this talk was that, although Skylon would be great, Mark Thomas seemed to be more open to other developmental pathways first.

He did say that they had done a small project recently but not what it was and that raised my ears. They're getting interest for their manufacturing ability too. Then there's the fact that the only people who almost look like customers (AFRL) have other ideas about what they want.  Skylon needs billions and who is going to provide them? I can see his feeling that REL have survived by the skin of their teeth, have a bit more time thanks to BAE and eventually HMG but they have most of the mountain still to climb.  So I am sure they will do whatever anyone else will pay them to do as I think they did with the Lapcat project.   

I would guess that they probably had a lot of money promised to them at one point and that it disappeared for reasons of the financial crisis or changes in fortune or Spacex or whatever (I remember the point at which 2-300 million seemed to be apparently lined up if I understood it right).   One can speculate, but I would guess that they are having a hard time visualising how they are going to avoid developing a whole lot of nearly usable technology and then suddenly  going "phut" before new investment can come along.

I got the impression too that he thinks there are some strange possibilities out there for the technology that they have developed and that you never know what it might lead to - that he isn't sure whether to be excited or stressed out.  Someone who has felt some ups and downs was my impression. Anyhow, with companies like this it was ever so. :-) That's why they are exciting. I hope they do work out some big weapons contract or deals to make components for other people or  one of those other bits of luck that famous technology companies often seem to need to get themselves kickstarted.







Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 03/19/2016 08:37 pm
t43562
**I remember the point at which 2-300 million seemed to be apparently lined up if I understood it right**

That's what a lot of us seemed to think, but to be honest that might just have been ourselves seeing things where there was nothing. REL never said such a thing.

But as you say, they've hung on until now by the skin of their teeth. The BAE buy-in was a surprise (to me at least) and although REL may welcome the money and profile BAE bring with them, it did seem rather cheap for the percentage stake that BAE got. It seems like they were down to few options with financial and commercial realities beginning to bite.

From the looks of things now, I would guess that Skylon, as originally imagined by Alan Bond and Co, is dead in the water. I'd guess that the Sabre tech is first going to appear in a USAF project.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 03/19/2016 09:41 pm
t43562
**I remember the point at which 2-300 million seemed to be apparently lined up if I understood it right**

That's what a lot of us seemed to think, but to be honest that might just have been ourselves seeing things where there was nothing. REL never said such a thing.

But as you say, they've hung on until now by the skin of their teeth. The BAE buy-in was a surprise (to me at least) and although REL may welcome the money and profile BAE bring with them, it did seem rather cheap for the percentage stake that BAE got. It seems like they were down to few options with financial and commercial realities beginning to bite.






From the looks of things now, I would guess that Skylon, as originally imagined by Alan Bond and Co, is dead in the water. I'd guess that the Sabre tech is first going to appear in a USAF project.

Regrettably I have to agree with you.

I believe Alan Bond might have taken a back seat in the company, and is acting on a semi-retired basis only.
He has put his heart and sole into the project and  Skylon looks more distant then ever now.

I think the company will now focus on development of various aspects of heat-exchanger components.
I think a none flight SABRE engine will be completed, if only to show just what can be accomplished with pre-cooler technology for many other applications.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: The Amazing Catstronaut on 03/19/2016 10:07 pm
Better just the pre-cooler than nothing. If the technology is picked up elsewhere and used for other applications, seeing another Skylon-esque project develop a decade down the road becomes increasingly more likely, and the team will have less of a money pile to climb for it.

Anything that enables high speed hypersonics is useful for designing similar airbreathing SSTOs. Certainly Skylon will inspire other SSTO designs for a long time coming.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: alanr74 on 03/20/2016 12:04 am
t43562
**I remember the point at which 2-300 million seemed to be apparently lined up if I understood it right**

That's what a lot of us seemed to think, but to be honest that might just have been ourselves seeing things where there was nothing. REL never said such a thing.

But as you say, they've hung on until now by the skin of their teeth. The BAE buy-in was a surprise (to me at least) and although REL may welcome the money and profile BAE bring with them, it did seem rather cheap for the percentage stake that BAE got. It seems like they were down to few options with financial and commercial realities beginning to bite.

From the looks of things now, I would guess that Skylon, as originally imagined by Alan Bond and Co, is dead in the water. I'd guess that the Sabre tech is first going to appear in a USAF project.

Cheap! I would say BAE possibly overspent. It's basically a massive risk, way to far in the future and could be out of date before it's born.

If anything BAE, RR (in kind) and the UK government are all part of keeping it afloat enough to make the project viable. hell even the Americans are taking an interest because there are possibilities for it.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 03/20/2016 06:59 am

From the looks of things now, I would guess that Skylon, as originally imagined by Alan Bond and Co, is dead in the water. I'd guess that the Sabre tech is first going to appear in a USAF project.

I didn't mean to set off a round of pessimism! I think that it's underestimating them to imagine that they haven't got their goal in sight all the time.   It just think that the path from here to there might have to pass through various stopovers.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Radical_Ignorant on 03/20/2016 09:00 am
And I'm not talking about "tech demonstrators", I'm talking about productive versions that reduce the development costs for each step.
Hard to disagree. Just I have problems to see how TSTO would simplify, make development cheaper, less risky and still competitive if all advantage of this system is to use different approach and as they say it's not down scalable.
Space X took proven technology, so it worked for them. How this approach could work for REL? Let's build engine and sell it? It's what they try to do - correct me if I'm wrong. Let whoever have any desire buy it and pay them cash so they can think of making Skylon or even not - maybe someone else will do Skylon or something different.

Secondly, there is what Zurbin is arguing against: let's do multiple middle steps. Let's push the final goal so far away that till this time will come, everything will change.

How's that worked out for Zubrin so far? He's now notorious for handwaving any problems in his own proposals while attacking any alternatives, to the point that I doubt anyone except a few rusted-on amazing people¹ take him at all seriously any more.

The most he's achieved is to reduce support for other technology development programs.

¹ Of course, one of those amazing people now owns his own rocket company. But ironically he practices the iterative development method I prefer.
That's not fair. What progress NASA achieved in their goals to go to moon and Mars and... Other tech programs, like VASIMIR, which is, as far as I read abut it, over promised even in theory. Additionally that was the goal of Zurbin to "don't waste resources on unknown purpose technology". Addionally that he is little aggressive and unfriendly in manner of his speeches have nothing to do with validity of his arguments.

How many projects with approach let's-first-develop-demonstrator were never continued because of, "nah, we are not interested in this anymore" from politicians.

Far fewer than have overpromised and underdelivered, and consumed way too much money chasing a technological mirage before being cancelled.
OK - that makes no sense. We could argue for ages about methodology how to count it. There are lot of examples when each approach worked and as well multiple examples for opposite.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/20/2016 10:49 am
True. I think SSTOs would have a much stronger case if we had space tugs.

However, with electric propulsion now being available to raise satellite orbits...
The biggest change in REL's development plans was the introduction of the Skylon Upper Stage, which is a reusable space tug
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 03/20/2016 11:21 am
True. I think SSTOs would have a much stronger case if we had space tugs.

However, with electric propulsion now being available to raise satellite orbits...
The biggest change in REL's development plans was the introduction of the Skylon Upper Stage, which is a reusable space tug

Without the upper stage  "space tug" Skylon would have been a none starter from the beginning. It's low orbit would have been of no use to the vast majority of it's prospective clients.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/20/2016 12:11 pm
Skylon needs billions and who is going to provide them? I can see his feeling that REL have survived by the skin of their teeth, have a bit more time thanks to BAE and eventually HMG but they have most of the mountain still to climb.  So I am sure they will do whatever anyone else will pay them to do as I think they did with the Lapcat project.   
REL are still waiting for the £60m promised over 2 years by George Osborne in 2014.


I don't think they've ever been interested in the manufacture of the actual spaceplane (are they called space planes?). It's always been about the engine as to build the actual spaceplane and the engine would be something that is just not feasible.
Historically it was REL's plan to just build the pre cooler for the enging.

However as size a company has to be to be able to handle complex tasks has shrunk they've realized they could make the whole engine as well.

REL's goal was always to form a consortium around the idea of building a spaceplance with Skylon as their model. The consortium could come up with a new design but REL aimed to deliver a design well enough thought out to get the consortium to go with it
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/20/2016 12:12 pm
Cheap! I would say BAE possibly overspent. It's basically a massive risk, way to far in the future and could be out of date before it's born.
Yes it's true BAE don't like risk.

They like their money from nice safe cost plus projects like Typhoon.

How many decades it take to go from signing the contract to getting a single vehicle to RAF service?
Quote
If anything BAE, RR (in kind) and the UK government are all part of keeping it afloat enough to make the project viable. hell even the Americans are taking an interest because there are possibilities for it.
Or perhaps it's because when REL have been adequately funded they have delivered what they said they could when they said they would?


That's precisely why trying to jump directly to a multi-billion Pound/Euro design seems so unlikely.

And I'm not talking about "tech demonstrators", I'm talking about productive versions that reduce the development costs for each step.
Skylon's (and hence SABRE's) size is the way it is because REL looked at the market and asked people what they wanted to meet their needs. This is the size that came back.
Quote
How many projects with approach let's-first-develop-demonstrator were never continued because of, "nah, we are not interested in this anymore" from politicians.

Far fewer than have overpromised and underdelivered, and consumed way too much money chasing a technological mirage before being cancelled.
A near perfect description of the X30 programme.

Which was REL asked ESA to perform an independent assessment of what they are planning and how. Something AFAIK no other company has done to demonstrate conclusively that what they are proposing is viable
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 03/20/2016 04:29 pm
I have problems to see how TSTO would simplify, make development cheaper, less risky and still competitive

A TSTO would still be too many steps at once, IMO. But more generally, TSTO would lower risk by reducing both the top speed required and the re-entry forces it has to cope with to allow low-cost reuse. (Remember, it's not just thermal effects.) Also, by reducing the demands on the airframe, by increasing the engineering margins, you lower the development costs.

But to clarify: most of my criticism isn't aimed at REL, but at their amazing people. I'm sure REL would be happy to work on a TSTO. Hell, even developing a version of the pre-cooler for stationary generator gas turbines. It's the amazing people not REL itself who are screeching that any alternative proposal is "wrong" or "stupid", even when those proposing it are holding money.

I do think that in the early years, REL pushed Skylon too heavily and that actually harmed their ability to attract interest. It created the perception that they weren't open to other ideas: "We have this product that can only be used on one extremely high risk, extremely costly development. Plz send ur monies." More recently, they seem to have opened up to other concepts (or at least changed the perception) and correspondingly, interest from potential investors has increased. Both investors and potential customers tend to avoid overly-obsessive inventors because they will be blind to alternative business opportunities and be high-maintenance to work with. There's a difference between enthusiastic and monomaniacal. One is hard working, the other is hard to live with. Surely you've noticed that in your own life? You tend to avoid working with shouty-obsessive types, even when they are otherwise skilled and useful.

JohnSmith19,
Make up your mind. One minute the technology itself is inherently unscalable, the next it's scaled that way only to fit the requirements of the client.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 03/21/2016 12:15 am
The technology is scalable.  Last time I asked, REL had not run into any upper limit, and there's no real reason you couldn't make it a bit smaller if that would fit the market better.

But if you try to make it a lot smaller, you run into problems.  Alan Bond has noted that a subscale development engine like the one they were planning originally would have issues with the extreme speed of the hydrogen turbopump (~300krpm or something), which would cost quite a bit to develop.  Hence their eagerness to go to full scale on the engine prototype when it looked like they'd have a chance to do so.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 03/21/2016 02:06 am
https://imgur.com/a/F87pA

...oh hey.  They've got new graphs based on the ones in Varvill & Bond (2003).  And SABRE 4 (as expected) performs vastly better than SABRE 2/3 - the shape of the Isp curve is similar, but this one peaks near 6000 seconds instead of a little past 3000.  And it's missing the hole around Mach 1; the peak is thus closer to Mach 1.3 or so rather than Mach 2.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Citizen Wolf on 03/21/2016 09:07 am
@93143
I totally missed that the graph was referring to Sabre 4. Thanks for pointing that out. I know we all pretty much guessed that they were going to go with Sabre 4, AFAIK no official announcement has been made yet, but I guess going from that graph the decision has been made for Sabre 4.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 03/21/2016 10:59 am
@93143
I totally missed that the graph was referring to Sabre 4. Thanks for pointing that out. I know we all pretty much guessed that they were going to go with Sabre 4, AFAIK no official announcement has been made yet, but I guess going from that graph the decision has been made for Sabre 4.

It is interesting that in that talk he made no mention of the fact that the frost control system was probably not going to be needed and mentioned that one person nearly let out the secret of it without pointing out that the patents are public and the secret is revealed anyhow.   So why have the talks have continued following the "SABRE3" story?  One reason could be that it allows them to give an interesting talk, impress everyone etc without giving away too much about their current train of thought.

With regard to publicising talks, I can well imagine that they are not interested in publicity *that much* and are doing them for the money. If so it's a bit sad. I think amazing people are future shareholders :-)


Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 03/21/2016 07:28 pm
@93143
I totally missed that the graph was referring to Sabre 4. Thanks for pointing that out. I know we all pretty much guessed that they were going to go with Sabre 4, AFAIK no official announcement has been made yet, but I guess going from that graph the decision has been made for Sabre 4.

It is interesting that in that talk he made no mention of the fact that the frost control system was probably not going to be needed and mentioned that one person nearly let out the secret of it without pointing out that the patents are public and the secret is revealed anyhow.   So why have the talks have continued following the "SABRE3" story?  One reason could be that it allows them to give an interesting talk, impress everyone etc without giving away too much about their current train of thought.

With regard to publicising talks, I can well imagine that they are not interested in publicity *that much* and are doing them for the money. If so it's a bit sad. I think amazing people are future shareholders :-)



The most likely reason that REL is giving these public talks now is simply recruitment, as was made clear in this presentation they're hiring 2-3 people every month, and in response to a question the audience was directed to the website for current job openings.
If you consider from REL's perspective they need to hire several hundred skilled engineers across a variety of disciplines  over the coming years and giving these lectures on a regular basis before a relevant audience does a lot to get the word out to potential employees.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 03/21/2016 10:34 pm
If there are problems shrinking the engines a simpler vehicle could have a single engine. This may mean a tiny payload to LEO (e.g. Falcon 1 Vs. Falcon 9) or a sounding rocket (e.g. Masten Xombie). Both options allow testing of reentry.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hanelyp on 03/22/2016 02:00 pm
As far as going single engine, it doesn't seem beyond consideration to divide the Sabre engine into an intake / turbopump assembly mounted centerbody, and rocket combustion chambers with nozzles in wing pods.  But that would require high pressure plumbing between the separated pieces.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/22/2016 02:47 pm
Original reply was lost in space/time :)

*REL itself, while rightly pointing out that the Skylon is DESIGNED for SSTO operations and is more "efficient" at that design point given it's design assumptions, explains that the Skylon AS DESIGNED is capable of and could be used as the suborbital first stage of a two-stage mission. It's right there in the Skylon Users Manual cited earlier. Page 8-9 give orbital figures while page 10 is for suborbital deployment. Note in either case for anything other than LEO all payloads have to include propulsion to deliver to their required destination. As noted above that's somewhere around 15mt to 18mt for Skylon delivery to orbit but the guide points out that Skylon can deliver up to it's maximum STRUCTURAL load of 30mt in a suborbital, two stage launch with payload supplied propulsion.  :)
That's the C2 manual, it isn't in the D1 manual, and was (if I recall correctly) disavowed by the REL team

It is in fact but still informative. If REL "disavowed" it they may want to take it off their website :)

Actually comparing both is instructive in and of itself:
C2: http://www.reactionengines.co.uk/tech_docs/SKYLON_User_Manual_rev1-1.pdf
D1: http://www.reactionengines.co.uk/tech_docs/SKYLON_Users_Manual_Rev_2.1.pdf

Quote
- but I personally suspect it's more because such activity is more the nailbiting style operations of vertical launch vehicle instead of the dull airline style operation they aim to achieve than for any show stopping reason.

Actually there was something of a "show-stopper" in the operation description; The Skylon had to be TOWED home after the suborbital mission which would indicate it used all its propellant getting the 30mt to suborbital velocity.

Note in comparing the above manuals that the current D1 finally gets to a full 17mt "payload" by several fudges such as lower orbital altitude and mass capability in that the vehicle is now capable of handling less than 20mt overall with a specification of a maximum of 17mt to LEO (600km as opposed to 800km in the C2) shown.

Nothing 'wrong' with this in any way it's refinement of the Skylon design, but it does point out the issues being discussed about SSTO vehicles.

Quote
Take out the SOMA, fuel cells and heavily insulated orbital tankage, lengthen (and strengthen?) the cargo bay and add some batteries you've got a reusable first stage to a TSTO launch vehicle. Perhaps slap a conventional jet engine in the SOMA hole and some inlet ducting to allow RTB.

No the Skylon as designed isn't going to work for a first stage per-se. As noted even if you pull out the cited systems you still need to radically restructure the air/spaceframe to handle the new loads which is going to no longer make it a "Skylon" anyway.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 03/22/2016 03:37 pm
As far as going single engine, it doesn't seem beyond consideration to divide the Sabre engine into an intake / turbopump assembly mounted centerbody, and rocket combustion chambers with nozzles in wing pods.  But that would require high pressure plumbing between the separated pieces.

Is running that plumbing a show-stopper? As I think about the single SABRE integrated into a fuselage I can see a couple of benefits compared to Skylon in addition to the challenges. With Skylon the wings need to be strong enough to support the SABREs on the ground, and any loads the SABREs would apply when flying/gliding during turbulence. More strength often means more mass. Their shape is presumably driven and even compromised by this - shorter wingspan is better for loads.

The wings on an integrated SABRE/fuselage design can be shaped and sized for the aerodynamics alone.

You also have a much simpler, more conventional shape for re-entry. (Although we've heard from REL that Skylon's unusual shape can re-enter just fine.)

I'm confidently guessing drag would be lower too.

So picture something like super-sized X-37B SSTO that takes off and lands on a runway. Throw in the V-tail from the X-37 and FASTT design for good measure so you don't need the transpiration cooled canards.

Payload would be small compared to the twin SABRE Skylon, but perhaps a runway launched, responsive, reusable spaceplane would interest the USAF? Sort of like a next gen X-37.

But all of this does hinge on the practicality of running that plumbing.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/22/2016 03:39 pm
True. I think SSTOs would have a much stronger case if we had space tugs.

However, with electric propulsion now being available to raise satellite orbits...
The biggest change in REL's development plans was the introduction of the Skylon Upper Stage, which is a reusable space tug

Er, and "upper-stage" has ALWAYS been implicit in the design of Skylon you DO understand that right? :) Skylon is ONLY capable of reaching LEO so it would have been useless for it's "designed" job of delivering commercial satellites if it could not put them into the proper orbit(s) as required.

The required delta-v from LEO (800km with the C2 or 600km for the D1) was always implied to be part of the "payload" mass to LEO carried by the Skylon. I think that was always one of the biggest confusions.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: The Amazing Catstronaut on 03/22/2016 03:44 pm

The required delta-v from LEO (800km with the C2 or 600km for the D1) was always implied to be part of the "payload" mass to LEO carried by the Skylon. I think that was always one of the biggest confusions.

Randy

Which in-turn leads to a smaller true payload. Shuttle also had the capability to have an extra upper stage as payload capability, if I'm reading this thread right.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/22/2016 04:06 pm
Secondly, there is what Zurbin is arguing against: let's do multiple middle steps. Let's push the final goal so far away that till this time will come, everything will change.

How's that worked out for Zubrin so far? He's now notorious for handwaving any problems in his own proposals while attacking any alternatives, to the point that I doubt anyone except a few rusted-on amazing people¹ take him at all seriously any more.

The most he's achieved is to reduce support for other technology development programs.

¹ Of course, one of those amazing people now owns his own rocket company. But ironically he practices the iterative development method I prefer.
That's not fair. What progress NASA achieved in their goals to go to moon and Mars and... Other tech programs, like VASIMIR, which is, as far as I read abut it, over promised even in theory. Additionally that was the goal of Zurbin to "don't waste resources on unknown purpose technology". Addionally that he is little aggressive and unfriendly in manner of his speeches have nothing to do with validity of his arguments.

Zubrin's more than a bit off-topic for this thread, as Skylon is one of those "technology development programs" he doesn't like because it doesn't get anyone (in his opinion) closer to Mars and never mind how much constant access does to ANY space program. But being honest Zubrin's trope has always been "don't waste resources on any ideas but mine" and he has made no bones about it. The fact that he is aggressive and unfriendly hasn't helped matters nor has the fact that he can't get everything but his exact ideas taken up as the one true way to Mars which makes him even more so.

Zubrin's goal sound laudable, at first, but the more you try to get into the details and the more questions you ask the less it seems so. Apollo is exactly the WRONG model to wish to emulate for a space program as it was a "one-trick" pony that did it's job but left very little to follow on and Zubrin simply won't except that HIS concept might have the same inherent flaw. The validity of his arguments beyond some of the more common sense ones, (ISRU was actually brilliant but it was already under consideration AND building up a Cis-Lunar ISRU and support infrastructure was 2/3rds of the cost of the entire VSI which Zubrin condemns) is suspect because of the assumptions they are based on.
A fact Zubrin refuses to even consider.

But lets get back to the actual subject which is Skylon...

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/22/2016 04:07 pm
To preserve the CoG protecting features you'd need to put it on top of the payload bay, like a sort of V1 cruise missile.
But that would leave the issue of how  you open the bay to get the payload out.

Belly doors, obviously. (Loading would be via an elevator-pit.)

As JS19 notes pretty SOP for bombers, and really MOST aircraft ordinance is bottom mounted, as well as various air-launched X vehicles and such. And with good reason because it greatly simplifies the mass shift and aerodynamic separation problems  of the vehicles involved. The original RASCAL concept assumed a mostly exo-atmospheric release would allow a simplified top-launched second stage with light weight doors but subsequent study by Georgia Tech showed this wasn't true and the vehicle would still require bottom mounted doors. The basic Skylon design would have to be radically re-designed to accommodate such a system so, again, I doubt it would be worth trying to adapt it for the job.

Something more akin to the University of Strathclyde CFASTT-1 with a recessed or belly bay.
http://strathprints.strath.ac.uk/41933/1/Brown_et_al_Towards_Robust_Aero_Thermodynamic_Predictions_for_Re_Usable_Single_Stage_to_Orbit_Vehicles.pdf

But that all depends on if you have to assume the wingtips are the only place to put the engines to address the CoG issues. (IIRC CoG was ONE issue that the wingtip engines addressed but there where supposed to be others, such as shock-interactions and keeping the intakes mounted as far away from the body as possible to reduce the air flow equations)
Frankly, while engine exhaust impingement is concerning a LOT of concepts used the aft end of the vehicle as an expansion surface for under-mounted engine exhaust. REL put the engines where they did because they are engine designers and not actually airframe designers.

Quote
but dropping off the excess mass of the booster stage and continuing the mission profile with a more efficient second stage that is fully reusable is as valid an assumption as not.

If you're using SABRE, then you've got that backwards. You'd have a reusable first stage (the Skylon-derivative), with an expendable all-rocket, vacuum-optimized upper-stage.

No reason to assume it would be expended since there would be incentive to bring in a fully reusable design if possible. A vacuum optimized, "bare-bones" stage was something the AF played with for quite a while and they pretty much always 'base-line' an expendable upper stage for planning purposes but they would be satisfied with a reusable upper stage vehicle if they can get it. The rather obvious point that's been made over and over again in their studies is that barring someone building them a custom stage for no-money they are going to have to accept compromises in the design and expendable/reusable isn't as easy to call as was the assumption.

(There's a reason most recent studies showed an "X-37B-like" orbital stage boosted by various types of upper stages :) )

On cross-range, you folks are over-thinking it :)

I was pointing out that the Air Force (and hence AFRL) happens to like the ability to move both the launch point AND the launcher around to keep Op-For guessing as much as possible. You can't do that with a ground launch system and even most air-launch systems have issues due to range requirements and restrictions. (Yes in fact they can and do often apply to the military as well, especially in peace-time) SABRE "air-breath's" so that's probably part of what AFRL is considering.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 03/22/2016 05:12 pm
Original reply was lost in space/time :)

*REL itself, while rightly pointing out that the Skylon is DESIGNED for SSTO operations and is more "efficient" at that design point given it's design assumptions, explains that the Skylon AS DESIGNED is capable of and could be used as the suborbital first stage of a two-stage mission. It's right there in the Skylon Users Manual cited earlier. Page 8-9 give orbital figures while page 10 is for suborbital deployment. Note in either case for anything other than LEO all payloads have to include propulsion to deliver to their required destination. As noted above that's somewhere around 15mt to 18mt for Skylon delivery to orbit but the guide points out that Skylon can deliver up to it's maximum STRUCTURAL load of 30mt in a suborbital, two stage launch with payload supplied propulsion.  :)
That's the C2 manual, it isn't in the D1 manual, and was (if I recall correctly) disavowed by the REL team

It is in fact but still informative. If REL "disavowed" it they may want to take it off their website :)

According to Mark Hempsell it's out.
http://forum.nasaspaceflight.com/index.php?topic=34964.msg1272415#msg1272415
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/22/2016 05:21 pm
As far as going single engine, it doesn't seem beyond consideration to divide the Sabre engine into an intake / turbopump assembly mounted centerbody, and rocket combustion chambers with nozzles in wing pods.  But that would require high pressure plumbing between the separated pieces.

Is running that plumbing a show-stopper?

As far as suggested above, probably. The SABRE is very much an "in-line" engine that would lose a lot of efficiency in trying to duct things around. A D-21 shape isn't really that bad of a basis for starting, it's been suggested for 2 or 3 combined cycle demonstrators that I can recall :)

Quote
As I think about the single SABRE integrated into a fuselage I can see a couple of benefits compared to Skylon in addition to the challenges. With Skylon the wings need to be strong enough to support the SABREs on the ground, and any loads the SABREs would apply when flying/gliding during turbulence. More strength often means more mass. Their shape is presumably driven and even compromised by this - shorter wingspan is better for loads.

(snip some other good stuff)

Skylon has been compared to being a hypersonic/orbital airship at times and really the current wing size is enough for fully loaded take off so getting back down is going to be rather "fluffy" in any case :) One thing to keep in mind is the Skylon basic shape is designed to be as easy as possible to fabricate. Avoiding complex shapes or curves in favor of simple (and well understood) rounded tanks. Once you start trying to wrap tankage around a single engine you have to move towards a more complex design which complicates fabrication and increases cost etc.

Trade offs and all that :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Space OurSoul on 03/22/2016 05:24 pm
As far as going single engine, it doesn't seem beyond consideration to divide the Sabre engine into an intake / turbopump assembly mounted centerbody, and rocket combustion chambers with nozzles in wing pods.  But that would require high pressure plumbing between the separated pieces.

Is running that plumbing a show-stopper? As I think about the single SABRE integrated into a fuselage I can see a couple of benefits compared to Skylon in addition to the challenges. With Skylon the wings need to be strong enough to support the SABREs on the ground, and any loads the SABREs would apply when flying/gliding during turbulence. More strength often means more mass. Their shape is presumably driven and even compromised by this - shorter wingspan is better for loads.

The wings on an integrated SABRE/fuselage design can be shaped and sized for the aerodynamics alone.

You also have a much simpler, more conventional shape for re-entry. (Although we've heard from REL that Skylon's unusual shape can re-enter just fine.)

I'm confidently guessing drag would be lower too.

So picture something like super-sized X-37B SSTO that takes off and lands on a runway. Throw in the V-tail from the X-37 and FASTT design for good measure so you don't need the transpiration cooled canards.

Payload would be small compared to the twin SABRE Skylon, but perhaps a runway launched, responsive, reusable spaceplane would interest the USAF? Sort of like a next gen X-37.

But all of this does hinge on the practicality of running that plumbing.

I've considered similar notions, but always assumed REL must have considered and discarded the single in-line SABRE configuration. But now that the subject has been broached :-) ....

In my thoughts, I assumed there would be a single (set of) combustion chamber (s) at the tail, further reducing the drag/wing-structure issues. I note that the exact placement of the intake + precooler could be tuned in order to maintain optimal CoG.

Some other issues/advantages leap to mind:
-Where would the bypass burners vent? It doesn’t seem impossible to have bypass air ducted all the way to the back of the vehicle. Many smaller ducts seem preferable, in order to maintain as straight a path as possible.
-Heat transfer to the cryo tanks from that plumbing
-The current vertical stabilizer is over-sized merely to provide sufficient control authority for a single-engine abort. With in-line thrust, the tail could be significantly smaller.
-REL might want to maintain two completely independent engine systems anyway, but there would be an opportunity for some small cost, complexity and mass savings by having a single engine albeit probably 2X the size in most of its components.
-inline thrust seems to offer small advantages in terms of control stability, and the tail-mount nozzle offers greater authority from thrust vectoring, at the cost of differential throttle for yaw control
-no issues with exhaust impinging on the airframe (could be a big issue, as we saw way up-thread)
-The ducting that runs the length of the vehicle could double as structural members. On the face of it, it seems unwise to have structural members go through such extreme thermal and therefore dimensional transformations, but I also read that SR72 expects to have a “warm” structure, so maybe it’s not mad.
-Perhaps the hot piping could be jacketed with a co-axial pipe carrying LH2 forwards, although REL might actually be embarrassed to field such a low-tech brute-force HX. It’d be a poor substitute for the current design’s enthalpy-recovery HX.
-Could the bypass burners’ exhaust be ducted out the canard’s tips? Perhaps the canard could be raked more strongly in order to reduce the amount of kinetic energy lost by redirecting the bypass air sideways.
-All this ducting might force a change in the OML, with presumably a slightly wider fuselage at the base, making Skylon look more like a Dreamchaser and less like an F-104.
-There have been some experiments with drag-reduction via venting small amounts of air through tiny holes all over an airframe. Perhaps an alternate use for bypass air, but not a system that would play well with a TPS.


Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Space OurSoul on 03/22/2016 05:27 pm
A question that’s unrelated to this layout scheme that occurred to me while wondering what to do about the bypass burners: With sufficient additional LH2 could the bypass air be utilized TAN style to enable the main nozzles’ expansion ratio to be tuned closer to vacuum optimum? It may not produce much (any) more thrust, the stoichiometry being only that appropriate to air not pure O2, but might it address the stability issues that would otherwise plague an over-expanded nozzle?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/22/2016 05:53 pm
Original reply was lost in space/time :)
As noted above that's somewhere around 15mt to 18mt for Skylon delivery to orbit but the guide points out that Skylon can deliver up to it's maximum STRUCTURAL load of 30mt in a suborbital, two stage launch with payload supplied propulsion.  :)
That's the C2 manual, it isn't in the D1 manual, and was (if I recall correctly) disavowed by the REL team

It is in fact but still informative. If REL "disavowed" it they may want to take it off their website :)
Having both versions shows how the design has been revised, so while removing it would be for claity I sincerely hope they don't.

You actually can't seem to access FROM their site, I found it in a round-a-bout fashion. The only one listed is the D1 manual.

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Actually there was something of a "show-stopper" in the operation description; The Skylon had to be TOWED home after the suborbital mission which would indicate it used all its propellant getting the 30mt to suborbital velocity.
I'm not sure why that's a show stopper? I've not seen an operational mode for Skylon that relights the SABREs (other than transitioning from air to LOX). Towing is their preferred method of site-to-site transport for Skylon

Really? I hadn't seen that anywhere as I understood the preferred method was self ferry.

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Take out the SOMA, fuel cells and heavily insulated orbital tankage, lengthen (and strengthen?) the cargo bay and add some batteries you've got a reusable first stage to a TSTO launch vehicle. Perhaps slap a conventional jet engine in the SOMA hole and some inlet ducting to allow RTB.

No the Skylon as designed isn't going to work for a first stage per-se. As noted even if you pull out the cited systems you still need to radically restructure the air/spaceframe to handle the new loads which is going to no longer make it a "Skylon" anyway.

I'm sorry that I was unclear, I was expressing how I though a SABRE-based TSTO craft could be designed - I quite agree you couldn't take a delivered Skylon D1 and turn it into one in the same way a mechanic may turn a hummer into a limo. From the design PoV I'm not quite sure why strengthening and lengthening would require the design would need to be radically restructured - in the same was as the D1 was not radically restructured from the C2.[/quote]

Sorry "I" wasn't clear either, I understood the intent but I was pointing out it's actually the opposite; The length is decreased with a smaller propellant load and the entire structure has to be reinforced to carry a significantly higher mass for a second stage system. And that's before we even open up the can or worms on how the second stage is deployed from the first :)

Quote

The required delta-v from LEO (800km with the C2 or 600km for the D1) was always implied to be part of the "payload" mass to LEO carried by the Skylon. I think that was always one of the biggest confusions.

Which in-turn leads to a smaller true payload. Shuttle also had the capability to have an extra upper stage as payload capability, if I'm reading this thread right.
As I understand it the Shuttle generally used the IUS, and the Centaur-G was designed to be flown (in Challenger or Discovery) but wasn't

In general I was pointing out the assumption was always there.

According to Mark Hempsell it's out.
http://forum.nasaspaceflight.com/index.php?topic=34964.msg1272415#msg1272415

Yup saw that. It's interesting the reasons for it but it's why AFRL is more interested in SABRE than in Skylon.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 03/22/2016 10:49 pm
As far as going single engine, it doesn't seem beyond consideration to divide the Sabre engine into an intake / turbopump assembly mounted centerbody, and rocket combustion chambers with nozzles in wing pods.  But that would require high pressure plumbing between the separated pieces.

Is running that plumbing a show-stopper? As I think about the single SABRE integrated into a fuselage I can see a couple of benefits compared to Skylon in addition to the challenges. With Skylon the wings need to be strong enough to support the SABREs on the ground, and any loads the SABREs would apply when flying/gliding during turbulence. More strength often means more mass. Their shape is presumably driven and even compromised by this - shorter wingspan is better for loads.

The wings on an integrated SABRE/fuselage design can be shaped and sized for the aerodynamics alone.

You also have a much simpler, more conventional shape for re-entry. (Although we've heard from REL that Skylon's unusual shape can re-enter just fine.)

I'm confidently guessing drag would be lower too.

So picture something like super-sized X-37B SSTO that takes off and lands on a runway. Throw in the V-tail from the X-37 and FASTT design for good measure so you don't need the transpiration cooled canards.

Payload would be small compared to the twin SABRE Skylon, but perhaps a runway launched, responsive, reusable spaceplane would interest the USAF? Sort of like a next gen X-37.

But all of this does hinge on the practicality of running that plumbing.

I've considered similar notions, but always assumed REL must have considered and discarded the single in-line SABRE configuration. But now that the subject has been broached :-) ....

In my thoughts, I assumed there would be a single (set of) combustion chamber (s) at the tail, further reducing the drag/wing-structure issues. I note that the exact placement of the intake + precooler could be tuned in order to maintain optimal CoG.

Some other issues/advantages leap to mind:
-Where would the bypass burners vent? It doesn’t seem impossible to have bypass air ducted all the way to the back of the vehicle. Many smaller ducts seem preferable, in order to maintain as straight a path as possible.
-Heat transfer to the cryo tanks from that plumbing
-The current vertical stabilizer is over-sized merely to provide sufficient control authority for a single-engine abort. With in-line thrust, the tail could be significantly smaller.
-REL might want to maintain two completely independent engine systems anyway, but there would be an opportunity for some small cost, complexity and mass savings by having a single engine albeit probably 2X the size in most of its components.
-inline thrust seems to offer small advantages in terms of control stability, and the tail-mount nozzle offers greater authority from thrust vectoring, at the cost of differential throttle for yaw control
-no issues with exhaust impinging on the airframe (could be a big issue, as we saw way up-thread)
-The ducting that runs the length of the vehicle could double as structural members. On the face of it, it seems unwise to have structural members go through such extreme thermal and therefore dimensional transformations, but I also read that SR72 expects to have a “warm” structure, so maybe it’s not mad.
-Perhaps the hot piping could be jacketed with a co-axial pipe carrying LH2 forwards, although REL might actually be embarrassed to field such a low-tech brute-force HX. It’d be a poor substitute for the current design’s enthalpy-recovery HX.
-Could the bypass burners’ exhaust be ducted out the canard’s tips? Perhaps the canard could be raked more strongly in order to reduce the amount of kinetic energy lost by redirecting the bypass air sideways.
-All this ducting might force a change in the OML, with presumably a slightly wider fuselage at the base, making Skylon look more like a Dreamchaser and less like an F-104.
-There have been some experiments with drag-reduction via venting small amounts of air through tiny holes all over an airframe. Perhaps an alternate use for bypass air, but not a system that would play well with a TPS.

Routing the hot bypass air does sound like the thorniest problem. It may not be worth it, and instead you dump it through bypass doors - a la SR71. But that comes with a performance penalty (no thrust from bypass burners, plus maybe drag) and complexity.

It's a good guess that Bond et al considered this sort of configuration in depth after the HOTOL cancellation, before coming up with Skylon.

IIUC the only thing that's a little different now is the temperature/pressure of the cooled air is less extreme with SABRE 4.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 03/23/2016 12:21 am
Note in comparing the above manuals that the current D1 finally gets to a full 17mt "payload" by several fudges such as lower orbital altitude and mass capability in that the vehicle is now capable of handling less than 20mt overall with a specification of a maximum of 17mt to LEO (600km as opposed to 800km in the C2) shown.

Nothing 'wrong' with this in any way it's refinement of the Skylon design, but it does point out the issues being discussed about SSTO vehicles.

Look closer.  Both designs have a payload of exactly 15 tonnes at 300 km altitude and 0° from an equatorial launch site.  D1's payload charts go to lower altitudes; C2's go to higher altitudes.

The "refinement" here is that the latest design work showed that reentry from 800 km might be a little optimistic, at least for the D1 airframe, and that there may be some advantage to be had in using orbits as low as 160 km vs. 250.  The nominal payload isn't part of the "refinement"; it's from market studies.  It's what the design is built around and hasn't changed.  If anything, D1 has better payload performance, because Skylon C was a rough exercise that apparently turned out to be a little short of its target when analyzed in depth, whereas Skylon D was supposed to establish a for-sure buildable design.

REL put the engines where they did because they are engine designers and not actually airframe designers.

Or maybe they put the engines where they did because it's actually the best place to put them if you aren't overly concerned about your design looking "futuristic" (ie: like the X-30).  These aren't really "hypersonic" engines, and may be better served by more traditional placement.

issues with exhaust impinging on the airframe (could be a big issue, as we saw way up-thread)

I thought we established that the heating rate was probably way too low?

Though with an engine stuck right to the fuselage, it might not be...  furthermore, an engine on the bottom would probably require a significantly heavier undercarriage to maintain ground clearance, and an engine on the top might have issues with being in the wake of the fuselage.

On the subject of running an engine through the fuselage, I always figured that would make the vehicle both larger and heavier than it needed to be, partly from volume and structure considerations and partly due to the extra insulation required.  Simplicity of manufacture would also be ill served by having to build the tankage around an engine duct.  And putting the precooler and turbocompressor at the front of the vehicle to manage CoG would multiply the issues because now the duct has to be both hot and high-pressure...

...not to mention that separating the precooler and compressor from the combustion chambers by some substantial fraction of 80 metres might make for an interesting engine integration problem...

With sufficient additional LH2 could the bypass air be utilized TAN style to enable the main nozzles’ expansion ratio to be tuned closer to vacuum optimum?

I believe the SABRE 4 uses low-expansion annular nozzles for airbreathing mode anyway.  The high-expansion-ratio central nozzle is only for rocket mode, which starts at around 28 km altitude.

I understood the preferred method was self ferry.

Not for Skylon C it wasn't.  The airbreathing Isp was too low.  Even now it isn't clear what's "preferred", but SABRE 4 and the D1 airframe changes do seem to enable much longer range.

it's actually the opposite; The length is decreased with a smaller propellant load

Keep in mind that the airframe size is already not driven by the propellant load.  D1.5's fineness ratio is a compromise between optimizing for low drag and optimizing for low mass; earlier iterations of D1 had a lot of wasted space inside.  With the payload bay as wide as it is, their options for scaling down are limited.

...

Also, this has been bugging me for a while:

I still see no reply to the very informative post of 93143. Any one with better numbers? let's have a polite discussion on how much off the design must be not to deliver. We all want to see the calculations of those claiming the margins are really small.
You need the numbers, the ACTUAL numbers to base such a conversation on. The numbers provided by 93143 are the best estimates available from the estimates and assumptions that REL has done so far which is all well and good. But they are still not actual performance figures.
If we had actual performance figures, there would be no room for said conversation.  The whole point is that we don't; the viability of the design is not known yet and depends on how close they can get to their estimates.  The question is: how much margin for error in those estimates do they have?  If my math is right, it seems they have quite a bit...
If their math is correct then your math is probably correct to their estimates... Which still doesn't eliminate the possibility that everyone's math isn't going to be met by actual performance. Doubtful but the chance is non-zero to a significant degree.

You're missing the point.  I wasn't calculating the performance of the vehicle.  I was calculating how badly wrong REL's estimates would have to be to kill their idea completely.  Saying "yes, but their numbers might not be right" doesn't engage the actual question.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 03/23/2016 04:23 am
but dropping off the excess mass of the booster stage and continuing the mission profile with a more efficient second stage that is fully reusable is as valid an assumption as not.
If you're using SABRE, then you've got that backwards. You'd have a reusable first stage (the Skylon-derivative), with an expendable all-rocket, vacuum-optimized upper-stage.
No reason to assume it would be expended

(People are reading too much into a throw-away line.)

I didn't mean that it had to be expendable, but that the expendability or reusability of the upper-stage is completely independent from the first stage.

I just meant that if you are using a SABRE-derived TSTO, then it will never be the second stage that is based on Skylon with a dumb booster stage. TSTO-Skylon would be the first stage, the second stage will just be a boring old rocket US.

I wouldn't expect a reduced SABRE propellant load. I'd expect the second stage to be pushed out of the cargo bay at around 200km altitude during a ballistic coast, doing around 6km/s

That was my image for STSO, except no payload bay, dorsal-mounted second stage/payload. (And probably lower staging, 80-100km.)

I wasn't calculating the performance of the vehicle.  I was calculating how badly wrong REL's estimates would have to be to kill their idea completely.

The issue isn't whether Skylon is possible, but whether it's practical. We don't need another unaffordable launcher. It doesn't take much to blow out the already-extraordinary design costs. Nor to blow out the ops costs.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/23/2016 04:04 pm
The issue isn't whether Skylon is possible, but whether it's practical. We don't need another unaffordable launcher.
And yet national governments keep funding them. While the LV is tied to a 2000Km artillery range they probably always will.  :(
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It doesn't take much to blow out the already-extraordinary design costs. Nor to blow out the ops costs.
Not even a "IMHO" to qualify that statement?

Aircraft cost models are basically built on mass, not complexity. Most of values for big ones will be derived from passenger aircraft. Such vehicles are very complex internally due to all the passenger support hardware. The models say nothing about this. Just that an aircraft that big is likely to cost this much. And Skylon is the size of an A380. Thrust wise its 2 1/8 bigger.

Keep in mind the equivalent cost models in the LV business predicts the total cost of the F1 & F9 programmes to first F9 launch about 10x what SX actually spent with NASA BAU processes and 6x with "more commercial" procurement.  ???

So I'll guess that SABRESkylon would have to have very bad project management to go over that level (run as a government cost plus contract, which is where most of the cost data for the LV business came from) and I would expect it to be somewhat below that level.

Physically Skylon is big, but internally it's relatively simple, once you get past the construction materials. Built in a clean sheet factory it should be possible to mfg it with a high degree of automation at a reasonable pace.

The thing I would love to know is how much has all the work REL put in already lowered those cost figures? My guess is that what they've done (over the last decades) has knocked quite a lot off that $12Bn  estimate, by turning "possibly, probably, maybe" into "yes, if we use parts of this diameter it will work" or "no, we'll have to revise the parameters for the D1.5 revision."
But that would disconnect their estimate from the numbers funding organizations would get when they run the cost models, so they won't talk about them.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/23/2016 04:05 pm
Er, and "upper-stage" has ALWAYS been implicit in the design of Skylon you DO understand that right? :) Skylon is ONLY capable of reaching LEO so it would have been useless for it's "designed" job of delivering commercial satellites if it could not put them into the proper orbit(s) as required.
Implicit certainly, but it was only relatively recently they started discussing the Skylon Upper Stage in detail and adding it to their main budget.
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The required delta-v from LEO (800km with the C2 or 600km for the D1) was always implied to be part of the "payload" mass to LEO carried by the Skylon. I think that was always one of the biggest confusions.
True. 15 tonnes was always the mass to LEO, and it was expected "something" in that mass would handle the getting to GEO part.

The required delta-v from LEO (800km with the C2 or 600km for the D1) was always implied to be part of the "payload" mass to LEO carried by the Skylon. I think that was always one of the biggest confusions.

Randy

Which in-turn leads to a smaller true payload. Shuttle also had the capability to have an extra upper stage as payload capability, if I'm reading this thread right.
15 tonnes is the true payload to LEO.  SUS is sized to put (IIRC) a 6 000 Kg comm sat on it's way to GEO, which is at the top of currently projected comm sat sizes.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/23/2016 04:05 pm
A D-21 shape isn't really that bad of a basis for starting, it's been suggested for 2 or 3 combined cycle demonstrators that I can recall :)
Agreed. If you must have a demonstrator logically you either a)Go with a scaled down version of your core design, to leverage all your CFD and wind tunnel work or b)Go as simple as possible, like an X plane. A test vehicle to demonstrate 1 key capability, with everything else kept as simple as possible.

I think scale models are tricky. They have most (all) of the difficult bits of the full size machine but only needed in 1 of or 2 of quantities, so as far as possible you want to get OTS stuff for the non tricky bits.

Personally I think you need to size the model to the sizes of the OTS bits you've got and avoid the special orders unless absolutely necessary. I'm especially thinking of the undercarriage. I think we all recall the Dream Chaser test vehicle using landing parts from a stock fighter and it's roll over when the landing gear door bay jammed.  :(
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Skylon has been compared to being a hypersonic/orbital airship at times and really the current wing size is enough for fully loaded take off so getting back down is going to be rather "fluffy" in any case :)
That's a bit unfair (and IIRC there really is a story about a hyper dirigible  :) ). Skylon's  structural loading is like that of an airship, but materially it's a very different beast.
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One thing to keep in mind is the Skylon basic shape is designed to be as easy as possible to fabricate. Avoiding complex shapes or curves in favor of simple (and well understood) rounded tanks. Once you start trying to wrap tankage around a single engine you have to move towards a more complex design which complicates fabrication and increases cost etc.
Very true, especially if LH2 is the fuel. Again it's back to keeping a demonstrator as cheap as possible. Cylindrical tanks are still the way to go.
I was pointing out that the Air Force (and hence AFRL) happens to like the ability to move both the launch point AND the launcher around to keep Op-For guessing as much as possible. You can't do that with a ground launch system and even most air-launch systems have issues due to range requirements and restrictions. (Yes in fact they can and do often apply to the military as well, especially in peace-time) SABRE "air-breath's" so that's probably part of what AFRL is considering.
I'll note Skylon is restricted by it's need to use a runway capable of handling a B36, of which the USAF owns 3 in CONUS. Naturally you take a payload hit for non equatorial launch but not letting anyone know you've launched may outweigh this.

However because Skylon is about 210 tonnes lighter landing would require much more minimal facilities. For the really impatient Skylon user I think a launch from one coast to full orbital velocity might be possible, deployment, then reentry in time to hit a runway on the other coast for landing, loading of LH2 and self ferry back to main operating base.

It sounds a bit involved to me but technically the launch asset never leaves the US, rather than wait a day for it to return to track over the original launch site (although Skylon's X-range is 2000Km+)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/23/2016 04:07 pm

Routing the hot bypass air does sound like the thorniest problem. It may not be worth it, and instead you dump it through bypass doors - a la SR71. But that comes with a performance penalty (no thrust from bypass burners, plus maybe drag) and complexity.
This is the issue.  The problem with it is
a)High volume, so the ducts have large diameters
b)Very hot. so they have to be made in either a high temperature alloy, or something like RCC.

So you've either got a high surface are of a heavy high temperature alloy like Inconel or a high surface area of a very expensive difficult to make (and oxidation pron) semi-ceramic.

Keeping pipe runs short and densities high by using a pre-cooler is part of how SABRE can do a T/W of 15:1 when a SCRamjet can do 2:1.
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It's a good guess that Bond et al considered this sort of configuration in depth after the HOTOL cancellation, before coming up with Skylon.

IIUC the only thing that's a little different now is the temperature/pressure of the cooled air is less extreme with SABRE 4.


You're missing the point.  I wasn't calculating the performance of the vehicle.  I was calculating how badly wrong REL's estimates would have to be to kill their idea completely.  Saying "yes, but their numbers might not be right" doesn't engage the actual question.
In electronic design this is sometimes called a "sensitivity analysis."

Skeptics seem to ignore this, thinking SABRE's payload sensitivity is that of a VTOL SSTO. What it actually shows is REL's calculations and simulations would have to very far out to fail to deliver a working engine or a working vehicle.

They also seem to ignore that unlike other systems SABRE has had independent scrutiny, partly to avoid such mishaps as the X30 PI using the wrong properties for air and deluding himself (and the USAF) that it was possible, when it simply wasn't.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 03/24/2016 03:58 pm
So according to this account of the 8th of March lecture,
https://www.reddit.com/r/ReactionEngines/comments/48a8uz/at_loughborough_university_on_8th_march_2016/

Skylon is being designed to have a life expectancy of ten years, which isn't something I've heard before.

This would imply a Skylon has a life of 200 launches or 10 years, which ever came first. So unless an operator is launching at least an average of 20 times a year the purchase price will have to be amortized over fewer launches.  An operator launching only 10 times a year would only have 100 launches to recoup the purchase price.
If the launch market is indeed elastic then this would suggest that Skylon operators would be incentivised to lower prices to stimulate launch rates.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/24/2016 04:44 pm
Not sure what keeps happening to the page settings but I'm not going to paste quotes and hope to avoid transferring them on :)

AFRL and TSTO: AFRL isn't interested in Skylon because while "nice" to have once someone else develops it, history has shown TSTO vehicles tend to fit their assumptions and requirements more. Hence SABRE as part of a TSTO system in a booster. Considering the militaries operational bias against LH2 for anything they didn't actually HAVE to have I really wouldn't be surprised if trades are still made to try and arrive at a methane/propane or kerosene fueled SABRE with the obvious results :)

Payload: C2 was structurally capable of carrying up to 30mt as designed but was ONLY capable of actually orbiting around 17mt. D1 is structurally capable of only carrying 17mt maximum. In any case part of that has to be an upper-stage to deliver the payload to its actual destination orbit. Currently Skylon couldn't act as a "booster" for an actual TSTO system due to structural and design limits. The main point though is REL is not considering looking at Skylon in any form other than SSTO while others have expressed interest in doing so. Neither approach is "wrong" but I am pointing out that REL itself has done the math that shows (with assumed structural ability) a SABRE powered, sub-orbital booster COULD in fact provide more payload than the basic Skylon to orbit. That's all.

Operations: REL has designed and assumed certain operational parameters for Skylon as an SSTO vehicle. AFRL is looking at a different set of assumptions and requirements. Again neither one is "right" or "wrong" as they are based on different criteria. What we WANT here is enough support for AFRL to at least get someone to build and test a ground-prototype SABRE and put the arguments there to rest. Getting from there to an operational vehicle is another kettle of fish all together.

Can't access the reddit article but stating a "life-expectancy" for an air frame in years is odd to say the least. Even "200 launches" is based on a ton of assumptions and airframe life is most often expressed in hours (of flight time) not years. (BTW? That would be over 80,000 hours :) ) And is dependent on component and materials versus stress and maintenance factors which are not known until you actually do the testing required to gather the data.

The statement would appear to have about as much validity as the claims that the Falcon-9R first stage can fly "10 times" which is unproven and un-provable until after you actually FLY the airframe at least 10 times...

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 03/24/2016 05:26 pm
{snip}
Can't access the reddit article but stating a "life-expectancy" for an air frame in years is odd to say the least. Even "200 launches" is based on a ton of assumptions and airframe life is most often expressed in hours (of flight time) not years. (BTW? That would be over 80,000 hours :) ) And is dependent on component and materials versus stress and maintenance factors which are not known until you actually do the testing required to gather the data.

The statement would appear to have about as much validity as the claims that the Falcon-9R first stage can fly "10 times" which is unproven and un-provable until after you actually FLY the airframe at least 10 times...

Randy

Expressing the life expectancy of an air frame in years may be odd but it is normal to express the shelf life of silicon chips in years. 10 years is about the maximum shelf life of a Flash Memory.
Ref: http://www.wdc.com/WDProducts/SSD/whitepapers/en/NAND_Evolution_0812.pdf (http://www.wdc.com/WDProducts/SSD/whitepapers/en/NAND_Evolution_0812.pdf)

Whether the entire Skylon needs replacing after 10 years or only its electronics would need investigating. Things like the hydraulics and seals may also need replacing.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 03/24/2016 05:40 pm
{snip}
Can't access the reddit article but stating a "life-expectancy" for an air frame in years is odd to say the least. Even "200 launches" is based on a ton of assumptions and airframe life is most often expressed in hours (of flight time) not years. (BTW? That would be over 80,000 hours :) ) And is dependent on component and materials versus stress and maintenance factors which are not known until you actually do the testing required to gather the data.

The statement would appear to have about as much validity as the claims that the Falcon-9R first stage can fly "10 times" which is unproven and un-provable until after you actually FLY the airframe at least 10 times...

Randy

Expressing the life expectancy of an air frame in years may be odd but it is normal to express the shelf life of silicon chips in years. 10 years is about the maximum shelf life of a Flash Memory.
Ref: http://www.wdc.com/WDProducts/SSD/whitepapers/en/NAND_Evolution_0812.pdf (http://www.wdc.com/WDProducts/SSD/whitepapers/en/NAND_Evolution_0812.pdf)

Whether the entire Skylon needs replacing after 10 years or only its electronics would need investigating. Things like the hydraulics and seals may also need replacing.

To be clear the exact quote I'm referencing is :

Quote
Mark said they were aiming for 10 year lifespan for Skylon and rapid reuse
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/24/2016 06:06 pm
To be clear the exact quote I'm referencing is :

Quote
Mark said they were aiming for 10 year lifespan for Skylon and rapid reuse

Thanks. As I noted I couldn't access the article :)
STILL an odd way of putting it.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 03/24/2016 09:56 pm
{snip}
Can't access the reddit article but stating a "life-expectancy" for an air frame in years is odd to say the least. Even "200 launches" is based on a ton of assumptions and airframe life is most often expressed in hours (of flight time) not years. (BTW? That would be over 80,000 hours :) ) And is dependent on component and materials versus stress and maintenance factors which are not known until you actually do the testing required to gather the data.

The statement would appear to have about as much validity as the claims that the Falcon-9R first stage can fly "10 times" which is unproven and un-provable until after you actually FLY the airframe at least 10 times...

Randy

Expressing the life expectancy of an air frame in years may be odd but it is normal to express the shelf life of silicon chips in years. 10 years is about the maximum shelf life of a Flash Memory.
Ref: http://www.wdc.com/WDProducts/SSD/whitepapers/en/NAND_Evolution_0812.pdf (http://www.wdc.com/WDProducts/SSD/whitepapers/en/NAND_Evolution_0812.pdf)

Whether the entire Skylon needs replacing after 10 years or only its electronics would need investigating. Things like the hydraulics and seals may also need replacing.

To be clear the exact quote I'm referencing is :

Quote
Mark said they were aiming for 10 year lifespan for Skylon and rapid reuse

Car lifetimes are expressed in years and miles.
10 years is the expected lifespan of a modern car. So they are building the Skylons to similar standards.
https://www.cardealpage.com/column14.html (https://www.cardealpage.com/column14.html)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: tatarana on 03/24/2016 10:04 pm
I did a little data extracting from   <https://imgur.com/a/F87pA>    and came back with the
following pictures, comparing Isp  and T/W   from several iterations of the SABRE engine.

I call it  SABRE  1/2/3    and   SABRE 4B   (most recent taken from the link above).
There is clearly a dramatic improvement from the first to second group.


Anyone cares to comment ? My technical background is not up to this task.

Tatarana

(edited) I made a mistake and put data for Sabre 4A that was really only an extrapolation from
old data from Sabre 2.  Apologies are due to everybody.   


Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 03/24/2016 10:49 pm
If I am not mistaken, early figures put Skylon lifetime to 30 years. Has this changed? the implications for the economics of the system are enormous if the expected lifetime is, indeed, only 10 years.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 03/25/2016 01:59 am
I did a little data extracting from   <https://imgur.com/a/F87pA>    and came back with the
following pictures, comparing Isp  and T/W   from several iterations of the SABRE engine.

I call it  SABRE  1/2/3    and   SABRE  4A (older data)   / SABRE 4B   (most recent taken from the link above).
There is clearly a dramatic improvement from the first to second group.

Also there is a marked difference between Isp and T/W  from SABRE 4A to 4B.

Where is your older data from?  Aside from Varvill & Bond (2003) and the C1 trajectory spreadsheet, I know of no sources that give (or can be analyzed to give) Isp curves for SABRE.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: tatarana on 03/25/2016 12:24 pm
I did a little data extracting from   <https://imgur.com/a/F87pA>    and came back with the
following pictures, comparing Isp  and T/W   from several iterations of the SABRE engine.

I call it  SABRE  1/2/3    and   SABRE  4A (older data)   / SABRE 4B   (most recent taken from the link above).
There is clearly a dramatic improvement from the first to second group.

Also there is a marked difference between Isp and T/W  from SABRE 4A to 4B.

Where is your older data from?  Aside from Varvill & Bond (2003) and the C1 trajectory spreadsheet, I know of no sources that give (or can be analyzed to give) Isp curves for SABRE.


Dear Sir

I made a mistake, already corrected in the original post. Figures were corrected also.
Thank you for your keen attention to details.
I put bellow the figures, again. The first figure is from the link   <https://imgur.com/a/F87pA>,
and the following 2 figures are mine.

Tatarana
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 03/27/2016 10:30 pm
New Skylon article with some  details on the test program at the end.

http://epizodsspace.no-ip.org/bibl/inostr-yazyki/aerospace-america/2016/3/8-11.pdf
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: oddbodd on 03/28/2016 03:18 am
News at 11: Researchers competing for aerospace R&D dollars have pessimistic view of alternatives to their own research!

Seriously? How long and how much have these people (plus all the other scramjet researchers) spent on scramjet tech? Rhetorical question; since the 50's and billions (probably more than the entire Skylon projected budget) And what have they delivered so far? A space launch system? Nope. A practical usable atmospheric vehicle? Nope. So far (IIRC correctly) we have a small vehicle that needs to be pre-boosted using rockets to get it up to a significant Mach number, then ignites the scramjet and gets up to something like Mach 5-8, flies for a max of 3 minutes, and is then dumped in the ocean. A launch vehicle with scramjets would not only need pre-boosting, but it would also need "something else" engine-wise to achieve orbit because the scramjet alone can't achieve it. And yet they get asked to comment on the SABRE engine? Why? You might as well ask the oil companies to comment on the viability of electric cars.

Disclaimer: I'm a Brit so, as well as a little bit of national pride, I also tend to root for the underdog, so I'm doubly invested in seeing Skylon succeed.

2nd disclaimer: Yes, I'm fully aware that scramjets are much further along in real terms than SABRE, but until the scramjets achieve reuse, testing will continue to be crazy expensive and slow. A key trait of the SABRE (in comparison) is that a great deal of the engine modes and cycles can be tested on the ground. Provided REL/SABRE isn't starved of cash and there are no "unknown unknowns" in the design I think the SABRE engine (not Skylon) could overtake (pun intended) scramjets in the not too distant future.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Oli on 03/28/2016 10:16 am

A scramjet can go up to Mach 10.

Mach 5 you can do with a turboramjet, to my knowledge.

Both have very bad thrust-to-weight ratios, but that's not a showstopper for atmospheric flight. Space launch is hardly a relevant market at this point.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 03/28/2016 02:55 pm
New Skylon article with some  details on the test program at the end.
http://epizodsspace.no-ip.org/bibl/inostr-yazyki/aerospace-america/2016/3/8-11.pdf

Looks like they are planning a single engine suborbital test vehicle. Props to AM_Swallow for predicting this.

EN: "The first flight test vehicle, with its  single  engine, would look more like a missile than a space plane, [Richard] Varvill [REL chief designer] says. It would be built to test the initial stage of a flight to space — taking off from the ground and accelerating to about Mach 5 with air-breathing engines — and then the engine would shut off and the air-craft would glide back to the ground."

As I said before, the company is clearly more flexible than people trying to "defend" the company.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: oddbodd on 03/28/2016 03:47 pm

A scramjet can go up to Mach 10.


Yeah, I didn't do enough searching when I wrote that, but to be fair, it only traveled at that speed for 10 seconds and that was way back in 2004. Since then as far as I could see lower speeds with longer durations have been the norm.


Mach 5 you can do with a turboramjet, to my knowledge.

Both have very bad thrust-to-weight ratios, but that's not a showstopper for atmospheric flight. Space launch is hardly a relevant market at this point.

Which was the main point of my post. The scramjet research and the people involved have no sensible bearing on space launch, so why the hell ask them to comment on SABRE?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/28/2016 05:13 pm
I'll note that people who love the SCRamjet concept never talk about it's T/W or the very large system needed to get it up to operating speed.

It took me years to discover the current expected T/W for a SCRamjet is about 2:1. That's less than the combined J58/nacelle combination (and the combination was key to making the system work) for the SR71 in the mid 1950's.

6 decades of effort (starting roughly in 1960 at Johns Hopkins APL) has produced this.

Historically fixed geometry ramjets have been good for a an operating Mach range of about 3 IE M1-M4 M2-M5 at most disregarding the weight of the rocket (including propellant) or air breathing engines to get it there.

SABRE design (as it was planned to from day one) covers the whole range from 0 to M23. The downside is it's poor (but only  by rocket standards) T/W ratio (which is 50% better than state of the art turbofans).

SABRE buys a huge propellant tank (provided by the airflow through it) and that makes it's relatively poor IE T/W ratio 7x better than SCRamjet, performance, coupled with it's excellent air breathing Isp good enough to get the job done.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 03/29/2016 12:24 am
New Skylon article with some  details on the test program at the end.
http://epizodsspace.no-ip.org/bibl/inostr-yazyki/aerospace-america/2016/3/8-11.pdf

Looks like they are planning a single engine suborbital test vehicle. Props to AM_Swallow for predicting this.

EN: "The first flight test vehicle, with its  single  engine, would look more like a missile than a space plane, [Richard] Varvill [REL chief designer] says. It would be built to test the initial stage of a flight to space — taking off from the ground and accelerating to about Mach 5 with air-breathing engines — and then the engine would shut off and the air-craft would glide back to the ground."

As I said before, the company is clearly more flexible than people trying to "defend" the company.

A good sign that they are actually bending metal.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 03/29/2016 05:41 am
As I said before, the company is clearly more flexible than people trying to "defend" the company.

No one ever complained about test vehicles.

The issue is that some feel the full DDT&E/certification program for a full-size commercial TSTO would be a waste of time and money, because it could easily cost as much or more to develop as Skylon without being nearly as cheap or easy to use (it might very well not be competitive with SpaceX, assuming F9 reusability goes well), and if SABRE works as expected and the airframe technology development doesn't trip over any major oversights, the technical risk associated with SSTO isn't high enough to make up the difference.  It's the same reason nobody is proposing a 3STO nowadays.

But it is hard to tell from the armchair, and there's still room for various opinions on this matter.

I tried to do some figuring on a SABRE-based TSTO one time.  As I recall, the numbers looked surprisingly bad, due in part to the extra hydrogen required for first-stage RTLS...  but maybe my design assumptions needed tweaking...
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 03/29/2016 06:52 am
Seems like REL may have some competition in this area & LM hope to fly their demonstrator by 2018.

Quote
That is according to Skunk Works head Rob Weiss, who confirmed that it would be an unmanned vehicle, at least at first. Hewson says the company’s long-term ambition is to “enable hypersonic passenger flights and easier access to space”.

Quote
Hewson, while displaying an artist’s rendering of the SR-72, said it would cost “less than $1 billion” to develop and fly a demonstrator aircraft the size of a the company's F-22 Raptor.

Quote
[In] 2016 [there] will be a decision on winners; more than one, likely, on one or both programmes,” says Weiss, adding that flight tests are planned for 2018.

https://www.flightglobal.com/news/articles/lockheed-pushing-1-billion-mach-6-airbreather-423198/
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: alanr74 on 03/29/2016 12:20 pm
Seems like REL may have some competition in this area & LM hope to fly their demonstrator by 2018.


Quote
https://www.flightglobal.com/news/articles/lockheed-pushing-1-billion-mach-6-airbreather-423198/

Forgive me if I'm wrong but that article seems to be about ramjets in a craft the size of a f22. I don't think it is even close to like for like.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 03/29/2016 01:17 pm
Scramjets have proven to be so successful, you know they only been trying to get them to work for the last 60 years or so, may this time they will succeed, I wouldn't place any money on it, especially as they fail to explain how they are going to get their aircraft up to Mach 6 to enable it to start operating the Scramjets.

http://epizodsspace.no-ip.org/bibl/inostr-yazyki/aerospace-america/2016/3/8-11.pdf

What this article neglect to say is that the whole engine can be tested and develop on the ground until all of the main problems, such as wear and tear of the combustion chambers are solved.

An well it not surprising the main criticism of Skylon come from people who are pursuing Scramjets, surely most funding for that dream would cease.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 03/29/2016 01:54 pm
Ramjets have proven to be so successful, you know they only been trying to get them to work for the last 60 years or so, may this time they will succeed, I wouldn't place any money on it, especially as they fail to explain how they are going to get their aircraft up to Mach 6 to enable it to start operating the Ramjets.
Think you may be referring to SCRamjets (Supersonic Combustion Ramjet) - there's a difference...
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 03/29/2016 03:07 pm
Seems like REL may have some competition in this area & LM hope to fly their demonstrator by 2018.


Quote
https://www.flightglobal.com/news/articles/lockheed-pushing-1-billion-mach-6-airbreather-423198/

Forgive me if I'm wrong but that article seems to be about ramjets in a craft the size of a f22. I don't think it is even close to like for like.

That's just the tech demonstrator that will be that size obviously not the final vehicle(s). The SR-72 alone if built will be 100 foot long plus, let alone any other vehicles that come from the research.

Scramjets have proven to be so successful, you know they only been trying to get them to work for the last 60 years or so, may this time they will succeed, I wouldn't place any money on it, especially as they fail to explain how they are going to get their aircraft up to Mach 6 to enable it to start operating the Scramjets.

http://epizodsspace.no-ip.org/bibl/inostr-yazyki/aerospace-america/2016/3/8-11.pdf

What this article neglect to say is that the whole engine can be tested and develop on the ground until all of the main problems, such as wear and tear of the combustion chambers are solved.

An well it not surprising the main criticism of Skylon come from people who are pursuing Scramjets, surely most funding for that dream would cease.

Do you honestly expect the full details of the research done by an organisation like Skunk Works to be in the public realm? There seems to be enough hints in the article and what is reported to suggest that elements of this technology have been developed out of the public gaze.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Archibald on 03/29/2016 04:58 pm
Quote
    REL put the engines where they did because they are engine designers and not actually airframe designers.

Quote

Or maybe they put the engines where they did because it's actually the best place to put them if you aren't overly concerned about your design looking "futuristic" (ie: like the X-30).  These aren't really "hypersonic" engines, and may be better served by more traditional placement.

They put the engines on the wingtips because they are near the center of gravity.
Alan Bond learned a lesson the hard way with HOTOL: the RB-545 at the back made HOTOL completely unbalanced, and they lost a lot of time, money, most of the payload to orbit and political support trying to solve that issue.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Archibald on 03/29/2016 05:36 pm
I'll note that people who love the SCRamjet concept never talk about it's T/W or the very large system needed to get it up to operating speed.

It took me years to discover the current expected T/W for a SCRamjet is about 2:1. That's less than the combined J58/nacelle combination (and the combination was key to making the system work) for the SR71 in the mid 1950's.

6 decades of effort (starting roughly in 1960 at Johns Hopkins APL) has produced this.

Historically fixed geometry ramjets have been good for a an operating Mach range of about 3 IE M1-M4 M2-M5 at most disregarding the weight of the rocket (including propellant) or air breathing engines to get it there.

SABRE design (as it was planned to from day one) covers the whole range from 0 to M23. The downside is it's poor (but only  by rocket standards) T/W ratio (which is 50% better than state of the art turbofans).

SABRE buys a huge propellant tank (provided by the airflow through it) and that makes it's relatively poor IE T/W ratio 7x better than SCRamjet, performance, coupled with it's excellent air breathing Isp good enough to get the job done.


Excellent post. Nowadays scramjet for SSTOs is dead since the NASP debacle more than twenty years ago. Scramjet research has been redirected toward hypersonic missiles.
As for NASP, Tony Dupont oversold a naive DARPA staff a widly optimistic design - but Dupont is a politically astute con man, see the DP-2 story - scandal http://www.wired.com/2007/06/hunters_folly_6
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 03/29/2016 06:51 pm
I'll note that people who love the SCRamjet concept never talk about it's T/W or the very large system needed to get it up to operating speed.

It took me years to discover the current expected T/W for a SCRamjet is about 2:1. That's less than the combined J58/nacelle combination (and the combination was key to making the system work) for the SR71 in the mid 1950's.

6 decades of effort (starting roughly in 1960 at Johns Hopkins APL) has produced this.

Historically fixed geometry ramjets have been good for a an operating Mach range of about 3 IE M1-M4 M2-M5 at most disregarding the weight of the rocket (including propellant) or air breathing engines to get it there.

SABRE design (as it was planned to from day one) covers the whole range from 0 to M23. The downside is it's poor (but only  by rocket standards) T/W ratio (which is 50% better than state of the art turbofans).

SABRE buys a huge propellant tank (provided by the airflow through it) and that makes it's relatively poor IE T/W ratio 7x better than SCRamjet, performance, coupled with it's excellent air breathing Isp good enough to get the job done.


Excellent post. Nowadays scramjet for SSTOs is dead since the NASP debacle more than twenty years ago. Scramjet research has been redirected toward hypersonic missiles.
As for NASP, Tony Dupont oversold a naive DARPA staff a widly optimistic design - but Dupont is a politically astute con man, see the DP-2 story - scandal http://www.wired.com/2007/06/hunters_folly_6

And what has any of that ancient history got to do with LM are doing now. That's the problem with people who oppose scramjet research they seem to live in the past and don't keep up with current developments.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 03/29/2016 09:36 pm
They put the engines on the wingtips because they are near the center of gravity.

We know.  The question is, could they be mounted closer to the fuselage, or even integrated into it?  Some think it might be better, others think it probably wouldn't.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/29/2016 10:33 pm
And what has any of that ancient history got to do with LM are doing now. That's the problem with people who oppose scramjet research they seem to live in the past and don't keep up with current developments.
This is not a programme.

It's a PR campagn to try to get the US Congress to set one up for them.

On topic for this thread I'd love to find out what REL reckons such a vehicle costs when it's put through the standard cost models for aircraft.

I'll bet it's much higher than $1Bn and historically DARPA has funded much lower than this level for their projects.

Always keep in mind modern aircraft research  departments are viewed as profit, [not as cost centers for the company to maintain their technical edge. From their PoV it's only necessary that it get funded, not that it works.

People don't oppose SCramjets. They simply note it's a massively over promised (air breathing to orbit !) technology and (equally) massively under delivered, 4 decades just to make the thrust generated exceed the drag the engine creates in operation is not impressive.  :(

I'll also note this "double barrelled" over & under engine concept still gives you a large diameter (because you're dealing with stagnation temperature airflow, not highly densified near liquid)  high surface area duct made of very heavy materials which untill cruise is basically dead weight.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/29/2016 10:35 pm
Excellent post. Nowadays scramjet for SSTOs is dead since the NASP debacle more than twenty years ago. Scramjet research has been redirected toward hypersonic missiles.
As for NASP, Tony Dupont oversold a naive DARPA staff a widly optimistic design - but Dupont is a politically astute con man, see the DP-2 story - scandal http://www.wired.com/2007/06/hunters_folly_6
For legal reasons I would not call him a con man.
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 03/29/2016 11:03 pm
And what has any of that ancient history got to do with LM are doing now. That's the problem with people who oppose scramjet research they seem to live in the past and don't keep up with current developments.
This is not a programme.

It's a PR campagn to try to get the US Congress to set one up for them.

On topic for this thread I'd love to find out what REL reckons such a vehicle costs when it's put through the standard cost models for aircraft.

I'll bet it's much higher than $1Bn and historically DARPA has funded much lower than this level for their projects.

Always keep in mind modern aircraft research  departments are viewed as profit, [not as cost centers for the company to maintain their technical edge. From their PoV it's only necessary that it get funded, not that it works.

People don't oppose SCramjets. They simply note it's a massively over promised (air breathing to orbit !) technology and (equally) massively under delivered, 4 decades just to make the thrust generated exceed the drag the engine creates in operation is not impressive.  :(

I'll also note this "double barrelled" over & under engine concept still gives you a large diameter (because you're dealing with stagnation temperature airflow, not highly densified near liquid)  high surface area duct made of very heavy materials which untill cruise is basically dead weight.

I'd put more money on LM in this competition at this time than REL if for no other reason that they are more likely to get their funding. Things like REL not receiving the money promised from government is going to do nothing but hamper their progress when it comes to financing.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Ravenger on 03/30/2016 09:48 am
So, what form is this single engine SABRE demonstrator likely to look like - something like the  Lockheed D21 drone perhaps?

That fits the description of looking more like a missile than an aircraft, and has the configuration you'd expect of a Mach 5 capable vehicle.

BAE's experience with the Taranis drone aircraft would be useful here, as number of its systems could be adapted for the SABRE demonstrator, especially the autonomous flight control systems.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 03/30/2016 10:06 am
I wonder how far this single engine vehicle can carry a spy camera at Mark 5?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 03/30/2016 10:43 am
And what has any of that ancient history got to do with LM are doing now. That's the problem with people who oppose scramjet research they seem to live in the past and don't keep up with current developments.
This is not a programme.

It's a PR campagn to try to get the US Congress to set one up for them.

On topic for this thread I'd love to find out what REL reckons such a vehicle costs when it's put through the standard cost models for aircraft.

I'll bet it's much higher than $1Bn and historically DARPA has funded much lower than this level for their projects.

Always keep in mind modern aircraft research  departments are viewed as profit, [not as cost centers for the company to maintain their technical edge. From their PoV it's only necessary that it get funded, not that it works.

People don't oppose SCramjets. They simply note it's a massively over promised (air breathing to orbit !) technology and (equally) massively under delivered, 4 decades just to make the thrust generated exceed the drag the engine creates in operation is not impressive.  :(

I'll also note this "double barrelled" over & under engine concept still gives you a large diameter (because you're dealing with stagnation temperature airflow, not highly densified near liquid)  high surface area duct made of very heavy materials which untill cruise is basically dead weight.

I'd put more money on LM in this competition at this time than REL if for no other reason that they are more likely to get their funding. Things like REL not receiving the money promised from government is going to do nothing but hamper their progress when it comes to financing.

Yet again a government promising money for a project that does not materialise.

I hope that at the very least the local MP is knocking on door of the treasury, asking "Where is our money".
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 03/30/2016 12:24 pm
And what has any of that ancient history got to do with LM are doing now. That's the problem with people who oppose scramjet research they seem to live in the past and don't keep up with current developments.
This is not a programme.

It's a PR campagn to try to get the US Congress to set one up for them.

On topic for this thread I'd love to find out what REL reckons such a vehicle costs when it's put through the standard cost models for aircraft.

I'll bet it's much higher than $1Bn and historically DARPA has funded much lower than this level for their projects.

Always keep in mind modern aircraft research  departments are viewed as profit, [not as cost centers for the company to maintain their technical edge. From their PoV it's only necessary that it get funded, not that it works.

People don't oppose SCramjets. They simply note it's a massively over promised (air breathing to orbit !) technology and (equally) massively under delivered, 4 decades just to make the thrust generated exceed the drag the engine creates in operation is not impressive.  :(

I'll also note this "double barrelled" over & under engine concept still gives you a large diameter (because you're dealing with stagnation temperature airflow, not highly densified near liquid)  high surface area duct made of very heavy materials which untill cruise is basically dead weight.

I'd put more money on LM in this competition at this time than REL if for no other reason that they are more likely to get their funding. Things like REL not receiving the money promised from government is going to do nothing but hamper their progress when it comes to financing.

Yet again a government promising money for a project that does not materialise.

I hope that at the very least the local MP is knocking on door of the treasury, asking "Where is our money".

That must also send out the wrong signals to potential future investors I would have thought. What does it say when your own government doesn't follow through on pledges like that?
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 03/30/2016 05:20 pm
Things like REL not receiving the money promised from government is going to do nothing but hamper their progress when it comes to financing.

That must also send out the wrong signals to potential future investors I would have thought. What does it say when your own government doesn't follow through on pledges like that?

I think you're taking that out of context, Mark Thomas's complaint  evidence to the committee was about  was about the pace of funding, not that it wasn't being followed through.


I hope that at the very least the local MP is knocking on door of the treasury, asking "Where is our money".
Quote from:  Nicola
Blackwood, http://data.parliament.uk/writtenevidence/committeeevidence.svc/evidencedocument/science-and-technology-committee/satellites-and-space/oral/29543.pdf
Would you mind writing to the Committee with the details of exactly what happened and the timings? It would be very helpful for the inquiry if we could understand exactly what has gone on and what bureaucratic hurdles you have had to overcome.

It was my understanding that none of this promised £60 million had been so far received?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 03/30/2016 08:15 pm
It was my understanding that none of this promised £60 million had been so far received?
From the report, it would appear your understanding is correct:

Quote
Mark Wood:
"Let me give you a local example. Reaction Engines received a tremendous boost when it
was announced that we had achieved £60 million of Government investment back in 2013,
but it took two and a half years to get the grant agreement signed, and three years later we
still have not seen any of those funds flowing into the company. Potentially, it is a missed
opportunity in that it has given our competitors an extra three years to try to find ways to
beat our engine."
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 03/30/2016 08:19 pm
So, what form is this single engine SABRE demonstrator likely to look like - something like the  Lockheed D21 drone perhaps?

When I first thought about it, that seemed like the most obvious solution. Except the D-21...

(http://www.air-and-space.com/20080309%20Palmdale/BL2_0412%20D-21%20right%20side%20l.jpg)

...burned JP-5 or similar fuel. A nice dense, hydrocarbon. Hence it only had relatively small toroidal tanks around its "waist".

SABRE burns liquid hydrogen, which is horribly low density. Even for a short flight, runway to Mach-5, the fuel volume will dominate the airframe.

In which case, I suspect they'll default to a simple engine-on-a-pylon...

(http://pegasus.bluefameupload.com/img/b5491d8c92acc951c5e348c43f5ea17f/blu1.jpg)

...with the airframe being mostly tank.

Being a smaller airframe than the full Skylon, it shouldn't be as sensitive to CoG issues as the fuel is used up. Plus putting the GNS and a large science package in the nose will balance out some of the mass of the engine. That lets you move the engine further rearward, letting you keep the pylon shorter without either dirty airflow or thermal issues on the tail, simplifying the design by keeping the line of thrust closer to the airframe.

Additionally, the pylon configuration should drop naturally out of prior air testing. I would expect them to carry a SABRE on a conventional jet aircraft, first to test the heat-exchange in flight, then to do subsonic hot runs; before switching to the self-contained test vehicle for the supersonic runs.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 03/30/2016 08:35 pm
Things like REL not receiving the money promised from government is going to do nothing but hamper their progress when it comes to financing.

That must also send out the wrong signals to potential future investors I would have thought. What does it say when your own government doesn't follow through on pledges like that?

I think you're taking that out of context, Mark Thomas's complaint  evidence to the committee was about  was about the pace of funding, not that it wasn't being followed through.


I hope that at the very least the local MP is knocking on door of the treasury, asking "Where is our money".
Quote from:  Nicola
Blackwood, http://data.parliament.uk/writtenevidence/committeeevidence.svc/evidencedocument/science-and-technology-committee/satellites-and-space/oral/29543.pdf
Would you mind writing to the Committee with the details of exactly what happened and the timings? It would be very helpful for the inquiry if we could understand exactly what has gone on and what bureaucratic hurdles you have had to overcome.

It was my understanding that none of this promised £60 million had been so far received?

I guess we would all agree the UK government should honour  their £60 million promise to RE.

How about  this forum creating a petition we could present to HM government.

I fully understand if the management of this forum do not wish to dip their toes into politics, but do we just say nothing and allow government to play politics with the aero space industry.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 03/30/2016 08:37 pm
(http://image.slidesharecdn.com/presentation13-120120151359-phpapp02/95/progress-on-the-skylon-reusable-spaceplane-28-728.jpg?cb=1327072631)
This was the original REL concept for a Nacelle Test Vehicle:
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 03/30/2016 09:28 pm
It was my understanding that none of this promised £60 million had been so far received?
From the report, it would appear your understanding is correct:

Quote
Mark Wood:
"Let me give you a local example. Reaction Engines received a tremendous boost when it
was announced that we had achieved £60 million of Government investment back in 2013,
but it took two and a half years to get the grant agreement signed, and three years later we
still have not seen any of those funds flowing into the company. Potentially, it is a missed
opportunity in that it has given our competitors an extra three years to try to find ways to
beat our engine."

I wonder why the government have suddenly got cold feet on this, Treasury meddling?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 03/30/2016 09:47 pm
I wonder why the government have suddenly got cold feet on this, Treasury meddling?

The impression given in the recent parliamentary hearing by Mark Thomas was just that the wheels grind slowly. I am not sure on the EU rules about state aid but you can imagine that some issue like that has probably gummed up the works. e.g. could it be that matching funds are required from industry? He didn't really explain and probably doesn't want to cause any upsets.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 03/30/2016 10:00 pm
I believe it's been mentioned in lectures that they had a major funder drop out so the government money which was unlocked by a certain level of private finance couldn't be. At least that's my understanding.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 03/30/2016 10:34 pm

It was my understanding that none of this promised £60 million had been so far received?

I guess we would all agree the UK government should honour  their £60 million promise to RE.

How about  this forum creating a petition we could present to HM government.

I fully understand if the management of this forum do not wish to dip their toes into politics, but do we just say nothing and allow government to play politics with the aero space industry.

Britain's new financial year starts on 5 April. That is less than a week away. With civil service reaction times do not do anything until May, unless you know the money has been denied. The new money could just be stuck in committee, (there are lots of committees).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 03/30/2016 10:50 pm
way to many committees in this country.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: topsphere on 03/31/2016 12:39 am
As I understand it (from what I have been told), the £60m pledge will be honoured, just taking a lot longer to sort through bureaucratic details with HMG and UKSA than REL would like.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lk555 on 03/31/2016 03:45 am
Has anyone looked at the possibility of applying tri-propellant technology to the SABRE? So the hydrogen is the main propellant taking up most of the volume of the airframe, and its still a big airframe even with reduced sizing of the oxygen tanks. So what about using a tri-propellent, use kerosene with the air breathing initial stage, then switch over to LH2 for the rocket portion where it would have a bigger advantage? Means you minimise storage size and therefore airframe mass? Plus that tank would need less insulation on ascent as its not cryogenic?

Sabre looks to be using a fuel rich staged combustion set up, has there been a kerosene staged combustion cycle? I suppose its just adding complexity to the entire thing, but am I completely out there?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: hkultala on 03/31/2016 03:49 am
Has anyone looked at the possibility of applying tri-propellant technology to the SABRE? So the hydrogen is the main propellant taking up most of the volume of the airframe, and its still a big airframe even with reduced sizing of the oxygen tanks. So what about using a tri-propellent, use kerosene with the air breathing initial stage, then switch over to LH2 for the rocket portion where it would have a bigger advantage? Means you minimise storage size and therefore airframe mass? Plus that tank would need less insulation on ascent as its not cryogenic?

Would not work. The cold hydrogen is needed to cool the air entering the engine during the airbreathing mode.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/31/2016 09:41 am
What this article neglect to say is that the whole engine can be tested and develop on the ground until all of the main problems, such as wear and tear of the combustion chambers are solved.
True. It is a fact the SSME combustion chambers tubes started failing at 1/3 their predicted lifespan. The extreme thermal shock during startup caused "dog kenneling" A fair chunk of the modern theory around thermal stress (IIRC it's called the "visco-elasto-plastic" stress model) was developed specifically to explain this massive discrepancy between theory and practice.

What people forget about SABRE is that LH2 is not used to cool the chambers tubes. That's done by deeply precooled air from the inlet and later LO2 from the tanks.

Both have been tested at DLR in Germany and worked fine.
Quote
An well it not surprising the main criticism of Skylon come from people who are pursuing Scramjets, surely most funding for that dream would cease.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/31/2016 03:08 pm

A scramjet can go up to Mach 10.

Just so we're all on the same page here, a "Supersonic Combustion Ramjet" (SCramjet) can (in theory :) ) accelerate indefinitely though material and aerodynamic issues would probably limit any "actual" SCramjet vehicle to somewhere below Mach-30. That's the "draw" of the concept and always has been.

Reality? Not so much. The X-43 managed somewhat below Mach-9.8 and that was with the rocket booster pushing it nearly to that speed BEFORE the SCramjet took over. As noted everything we've seen (both on the bench and now with flight testing) shows the SCramjet isn't an efficient or effective accelerator.

Then again, that's not what the military is looking at them for :)

Quote
Mach 5 you can do with a turboramjet, to my knowledge.

Turboramjets have been operated up to around Mach-4, with modifications and various techniques they can probably be pushed to Mach-5 or a bit over but it's not worth the cost of doing so. (Mostly because doing so requires removing the turbofan/jet from the ramjet duct to allow the ramjet to reach peak efficiency in operation which would then allow speeds up to Mach-10 according to people who actually designed and built ramjets for a living. The same folks were telling anyone who would listen since the 1960s that a SUB-sonic combustion ramjet could do Mach-10 if anyone was willing or needed to build one. The got drowned out by the SCramjet crowd)

Just an FYI, but a standard low-to-medium bypass turbofan can be used to get to Mach-4 and some change with a few bolt-on systems but there's been no 'need' for doing so.

Randy

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/31/2016 03:09 pm
I'll note that people who love the SCRamjet concept never talk about it's T/W or the very large system needed to get it up to operating speed.

Well in honesty you need some added systems to go from "zero-to-start" for any combined cycle system. That includes SABRE :)

But I agree that the SCramjet-uber-alles crowd tends to downplay FAR to much of the required effort. Sure you can accelerate to Mach-30+ but if it takes a week-and-a-half to do so what's your operational incentive?

Quote
It took me years to discover the current expected T/W for a SCRamjet is about 2:1. That's less than the combined J58/nacelle combination (and the combination was key to making the system work) for the SR71 in the mid 1950's.

Actually BENCH SCramjets have had much higher T/W ratios but working with a "real" atmosphere (and a real intake and exhaust rather than a lab set up) hasn't been anywhere near where it was predicted from the bench tests.

Quote
6 decades of effort (starting roughly in 1960 at Johns Hopkins APL) has produced this.

And if past experience has taught us anything it will take a few more decades of SERIOUS work (and money) to get to an effective operational system. The main problem is, while SCramjet LOOKS good in theory it has very few 'real-world' operational uses. Unfortunately SABRE, ATR, SERJ and most other proposed "space" vehicle air-breathing systems have the same problem.

Quote
Historically fixed geometry ramjets have been good for a an operating Mach range of about 3 IE M1-M4 M2-M5 at most disregarding the weight of the rocket (including propellant) or air breathing engines to get it there.

"Fixed" inlets yes, but like SABRE almost no one suggests using a fixed inlet/exhaust for a space launch accelerator system. (And interestingly, fixed inlet systems have turned out to be more flexible than assumed with higher speed 'sweet-spots' above their design points. Combined with some additive (injection) systems it's been shown that you can achieve similar results to having a fully adjustable mechanically variable inlet system with far less mass and cost. However this method isn't as operationally flexible as actual adjustable inlets which is why it was not pursued beyond testing)

And I have to disagree that unlike the SCramjet crowd those who suggest various combined cycle space launch concepts DO include and are very obvious at pointing out the combined systems mass. That's actually a major point in that combined systems mass significantly less than separate systems employed in the same vehicle.

Quote
SABRE design (as it was planned to from day one) covers the whole range from 0 to M23. The downside is it's poor (but only  by rocket standards) T/W ratio (which is 50% better than state of the art turbofans).

No different than several other proposed and tested combined cycle system really. SABRE buys a few advantages with the extensive pre-cooling rather than going down the dead-end "Liquid Air Cycle" route that most prior work in the 50s and 60s went but most more modern concepts (since the 1970s) have avoided that pitfall. Strangely enough, simply injecting water into the intake of a semi-modern low-bypass turbofan like the F100 will double the T/W and it would still have a higher ISP than the SABRE. Toss in significant pre-cooling of the air such as the SABRE pre-cooler system and it increases yet again with no ISP loss.

However, (as noted) this won't get you much past Mach-5 and is only an air-breathing mode concept.

SABRE isn't alone in being designed for SSTO operations from the start is my main and significant point.

Quote
SABRE buys a huge propellant tank (provided by the airflow through it) and that makes it's relatively poor IE T/W ratio 7x better than SCRamjet, performance, coupled with it's excellent air breathing Isp good enough to get the job done.

True, for a "versus-SCramjet" comparison, but it compares more evenly with just about any combined cycle engine system that doesn't (which is difficult these days I will admit) include a SCramjet.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/31/2016 03:54 pm
This was the original REL concept for a Nacelle Test Vehicle:

Would seem to be about the right size but mass looks really, really low. The GTX test vehicle (RBCC engine test bed) for a similar flight test pattern was about the same size, (37.3ft=11.3m long by 14.5ft=4.4m wingspan compared to 29.5ft=9m long and 11.5ft=3.5m wingspan) but mass was much higher than 1000kg. (Propellant mass for the LH2 was listed as 589lbs/267kg) Even without the SRBs the flight test vehicle was around 7,937lbs/3600kg fully fueled and it was using some pretty light-weight structural materials.
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20030055618.pdf

Wingspan alone is going to have to go up to support an HTOL take off and glide back whereas the GTX was VTO and only used stub wings and body lift because it 'started' at over Mach-2.

The D-21 (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000004765.pdf) was 42.9ft/13.07m long, 7.1ft/2.1m high with a 19.1ft/5.8m wingspan using JP-7/8 fuel though as noted it was in a very compact tank compared to LH2. Interestingly, modifications for the DRACO RBCC concept test bed, changed the overall dimensions very little, (44"+"ft long, wingspan to 19.5ft, etc http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000012490.pdf) though the mass went up, it was not as much as one might expect. Given the configuration of the SABRE compared to the more integrated DRACO RBCC I suspect it would probably be EASIER to modify the D-21 to house a small scale SABRE prototype. If of course the SABRE can be scaled down sufficiently.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 03/31/2016 07:44 pm

The D-21 (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000004765.pdf) was 42.9ft/13.07m long, 7.1ft/2.1m high with a 19.1ft/5.8m wingspan using JP-7/8 fuel though as noted it was in a very compact tank compared to LH2. Interestingly, modifications for the DRACO RBCC concept test bed, changed the overall dimensions very little, (44"+"ft long, wingspan to 19.5ft, etc http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000012490.pdf) though the mass went up, it was not as much as one might expect. Given the configuration of the SABRE compared to the more integrated DRACO RBCC I suspect it would probably be EASIER to modify the D-21 to house a small scale SABRE prototype. If of course the SABRE can be scaled down sufficiently.
Interesting idea about using the D11 as the DRACO test bed. It seemed quite reasonable. Very pragmatic, and relatively cheap. I guess it got lost in the budget. Too bad.  :(

AFAIK the joker in scaling down SABRE (and why REL are reluctant to do one) was to be a real test of the engine it's got to be at full chamber pressure.  That combo of full pressure but low flow rates gives a very high speed turbo pump design.

Now if SABRE 4 allows a lower chamber pressure for the air breathing part that may make the pump design more reasonable. Obviously the RL10 demonstrates expansion drive in fairly small sizes is possible. I think the chamber pressure was the issue.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 03/31/2016 09:19 pm

The D-21 (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000004765.pdf) was 42.9ft/13.07m long, 7.1ft/2.1m high with a 19.1ft/5.8m wingspan using JP-7/8 fuel though as noted it was in a very compact tank compared to LH2. Interestingly, modifications for the DRACO RBCC concept test bed, changed the overall dimensions very little, (44"+"ft long, wingspan to 19.5ft, etc http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000012490.pdf) though the mass went up, it was not as much as one might expect. Given the configuration of the SABRE compared to the more integrated DRACO RBCC I suspect it would probably be EASIER to modify the D-21 to house a small scale SABRE prototype. If of course the SABRE can be scaled down sufficiently.
Interesting idea about using the D11 as the DRACO test bed. It seemed quite reasonable. Very pragmatic, and relatively cheap. I guess it got lost in the budget. Too bad.  :(

Actually it was a good idea but getting the D21 to the point where it was going to be able to work at speeds over the 'nominal' 3.5 was going to cost to much. Up to that point the D21 was great, beyond it? Not so much. And in the end simply "flying" the DRACO wasn't worth it. Pretty much the same story for any combined cycle power plant really.

Quote
AFAIK the joker in scaling down SABRE (and why REL are reluctant to do one) was to be a real test of the engine it's got to be at full chamber pressure.  That combo of full pressure but low flow rates gives a very high speed turbo pump design.

Now if SABRE 4 allows a lower chamber pressure for the air breathing part that may make the pump design more reasonable. Obviously the RL10 demonstrates expansion drive in fairly small sizes is possible. I think the chamber pressure was the issue.

Which is what I gathered from what REL was saying which means at 'best' we're talking about a single, full-size, Skylon/SABRE nacelle as a test vehicle which is NOT going to be cheap in any sense of the word. And there's the sticking point :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 04/01/2016 07:56 am
This was the original REL concept for a Nacelle Test Vehicle:

Would seem to be about the right size but mass looks really, really low... 

...Given the configuration of the SABRE compared to the more integrated DRACO RBCC I suspect it would probably be EASIER to modify the D-21 to house a small scale SABRE prototype. If of course the SABRE can be scaled down sufficiently.

Randy

I agree; what I remembered shortly after digging out this concept was REL's thinking at the time:

Almost every aspect of SABRE can be tested on the ground - except the aerodynamics (e.g. maintaining shock on lip) of the nacelle under real flight conditions. Hence this is a NACELLE Test Vehicle, probably boosted by non air-breathing conventional rockets mounted within.

Explains the low mass and the lack of significant LH2 storage volume (and the loss of the endearing banana shape!).

Not sure whether this half-way approach would ever come back into favour...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 04/02/2016 03:41 am
The scramjet research and the people involved have no sensible bearing on space launch, so why the hell ask them to comment on SABRE?

Scramjet researchers may be biased.  But so might the people at REL.  Scramjet researchers are experts on propulsion at these speeds.  There's basically just them and REL.  Both could potentially have some bias, but if you want a perspective from outside REL, there's nobody better to give it than scramjet researchers.

Whether the goal is space launch or missiles, it's still propulsion at hypersonic speeds.

So, it makes sense to be wary of what scramjet researchers say about Skylon, and keep a critical frame of mind, but not to dismiss it out of hand.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/02/2016 08:13 pm
The scramjet research and the people involved have no sensible bearing on space launch, so why the hell ask them to comment on SABRE?

Scramjet researchers may be biased.  But so might the people at REL.  Scramjet researchers are experts on propulsion at these speeds.  There's basically just them and REL.  Both could potentially have some bias, but if you want a perspective from outside REL, there's nobody better to give it than scramjet researchers.

Whether the goal is space launch or missiles, it's still propulsion at hypersonic speeds.

So, it makes sense to be wary of what scramjet researchers say about Skylon, and keep a critical frame of mind, but not to dismiss it out of hand.
Actually there are also the groups who build ramjets for missiles.

But that's not really considered "research" as they can deliver systems that work already.  M3.5-4 has certainly been proven since the late 70's.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Radical_Ignorant on 04/04/2016 02:17 pm
The technology is scalable.  Last time I asked, REL had not run into any upper limit, and there's no real reason you couldn't make it a bit smaller if that would fit the market better.

But if you try to make it a lot smaller, you run into problems.  Alan Bond has noted that a subscale development engine like the one they were planning originally would have issues with the extreme speed of the hydrogen turbopump (~300krpm or something), which would cost quite a bit to develop.  Hence their eagerness to go to full scale on the engine prototype when it looked like they'd have a chance to do so.

Upper scale is existing infrastructure. Even A380 was scaled up to where infrastructure allowed and no more. And there are more money as for now in civilian jets than in space transports.

But making it smaller. I heard that it's rather impossible or would not reduce costs at all. However I won't provide link. I think it was one of their speeches, but there is only my far from perfect memory for that. If you can prove me wrong by some link, I'd be grateful. That would be really nice if they could scale it down and make cheaper version. I thought that was the reason they go for full scale.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Ravenger on 04/04/2016 03:28 pm
According to REL the main issue with scaling down the SABRE engine is the LH2 turbopump. A smaller turbopump requires much higher RPM, which makes it much more technically difficult to produce. I think the figure quoted was £100m just to develop the turbopump alone.

This is why REL previously ruled out a sub-scale SABRE demonstrator.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 04/04/2016 03:48 pm
Right, that is one component that we believe is hard to scale down. But the rest of the Skylon system is sized to launch comsats - one of the easiest business cases to make for a launcher.

However IIUC, if REL find a customer with a fat wallet that needs a smaller payload, then there are many conceivable SABRE based vehicles of various sizes that could be designed - even if they all do come with big H2 turbo pumps.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Radical_Ignorant on 04/04/2016 04:02 pm
But to clarify: most of my criticism isn't aimed at REL, but at their amazing people. I'm sure REL would be happy to work on a TSTO. Hell, even developing a version of the pre-cooler for stationary generator gas turbines. It's the amazing people not REL itself who are screeching that any alternative proposal is "wrong" or "stupid", even when those proposing it are holding money.

I do think that in the early years, REL pushed Skylon too heavily and that actually harmed their ability to attract interest. It created the perception that they weren't open to other ideas: "We have this product that can only be used on one extremely high risk, extremely costly development. Plz send us ur monies"
{snip}

Can't disagree. As Space X, as I imagine it, didn't went to investors telling them "we want to colonize Mars somewhere 30-50 years down the road. Wanna give us few hundreds millions?" Space X goal is hard and then rarely even talked about. All focus is on next step, which in SX case is to make cheap space transport.

And here for REL they should/are focusing on engine. And if there is a way to generate revenue out of this engine then that's the way to go no matter if payer idea makes sense. If someone want to makes cats go to Internet faster using this engine let them do it if he pays btw for what REL guys and we all dream about :p
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/04/2016 06:49 pm

Can't disagree. As Space X, as I imagine it, didn't went to investors telling them "we want to colonize Mars somewhere 30-50 years down the road. Wanna give us few hundreds millions?" Space X goal is hard and then rarely even talked about. All focus is on next step, which in SX case is to make cheap space transport.
They didn't go to investors at all Musk was rich enough to fund F1 and F9.

REL have had to justify every penny they have been given.
Quote
And here for REL they should/are focusing on engine. And if there is a way to generate revenue out of this engine then that's the way to go no matter if payer idea makes sense. If someone want to makes cats go to Internet faster using this engine let them do it if he pays btw for what REL guys and we all dream about :p
A fair point.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 04/04/2016 11:26 pm
Upper scale is existing infrastructure.

Skylon isn't intended to use existing infrastructure.  As I recall, REL were envisioning a new-built spaceport (or a new-built facility at an existing spaceport like Kourou) designed specifically to service it.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Radical_Ignorant on 04/05/2016 07:32 am

Can't disagree. As Space X, as I imagine it, didn't went to investors telling them "we want to colonize Mars somewhere 30-50 years down the road. Wanna give us few hundreds millions?" Space X goal is hard and then rarely even talked about. All focus is on next step, which in SX case is to make cheap space transport.
They didn't go to investors at all Musk was rich enough to fund F1 and F9.

REL have had to justify every penny they have been given.

No, Musk money was not enough. https://www.quora.com/How-much-money-has-SpaceX-raised-and-who-from (and that's only the beginning) But yeah, you are right, they needed little more money, not all the money. So had much more freedom in how to operate. And the second difference is NASA - early contract allowed them to develop F9. IIRC Musk money was enough for three failed launches of F1 (and building company). At least that what he was saying at the very start.
But I'm getting little off topic.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 04/05/2016 11:34 am
(it really helps that Kourou has cleanroom standard vehicles with an airlock for moving things between buildings)

It isn't that great of idea. Just an unnecessary move.  Just put the fairing on the payload before bringing it to the launch vehicle.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 04/05/2016 10:19 pm
The scramjet research and the people involved have no sensible bearing on space launch, so why the hell ask them to comment on SABRE?

Scramjet researchers may be biased.  But so might the people at REL.  Scramjet researchers are experts on propulsion at these speeds.  There's basically just them and REL.  Both could potentially have some bias, but if you want a perspective from outside REL, there's nobody better to give it than scramjet researchers.

Whether the goal is space launch or missiles, it's still propulsion at hypersonic speeds.

So, it makes sense to be wary of what scramjet researchers say about Skylon, and keep a critical frame of mind, but not to dismiss it out of hand.

Actually I have to disagree because SCramjet researches have a biased opinion BECAUSE SABRE is somewhat of a "hypersonic" propulsion system which therefore is directly in competition with them and they are pretty vocal about it. Yes REL has some bias' about SCramjets, so does anyone who's ever worked on or built subsonic combustion ramjets, including the majority of folks who initially worked the hardest ON SCramjet research.
(The same folks that actually BUILT operational ramjets all the way into the '90s before SCramjet research managed to convince everyone that ramjets were obsolete)

And ask yourself if you really get any good information from someone who has never researched or worked on anything BUT SCramjets on systems they therefore know nothing about? (Hint? While yes aero-propulsion systems are generally the same the devil is in the details and the people you're talking to in fact don't really know that much about anything BUT SCramjet propulsion)

The point, and it's quite a valid one, is that asking someone who works on SCramjets about a zero-to-hypersonic propulsion system is going to get you a vary biased and probably highly inaccurate answer because the person you're asking ONLY works with hypersonic to VERY-HIGH hypersonic propulsion and not anything that can start from zero and even go supersonic let alone reach hypersonic speeds on it's own. And you're asking the question of someone who very well knows that any positive answer can potentially cause their own research to lose funding, support, or interest.

SABRE barely touches hypersonic speed, (at most Mach-6 when "hypersonic" is at least Mach-5) it uses a compressor, it has rocket engines, and it takes off from a runway all of which a SCramjet doesn't do and frankly no one has been designing them to for almost 40 years. SCramjet researchers have all been concentrating on getting from Mach-7, (where a SCramjet starts working efficiently if at all) to higher speeds, the closest they have come in the last 20 years to addressing the "zero-to-" issue is suggesting an integral rocket/ramjet/SCramjet but since the 'duel-mode' SCramjet (a subsonic and supersonic combustion ramjet in one engine) never panned out and SCramjet research has sucked up all the money for integral rocket/ramjet research there has been nothing else but to launch SCramjet test articles by brute force rocket launch. Yet the same folks will tell you how wonderful the "theory" is that once we have SCramjets we can "easily" fly to Mach-26+ in the atmosphere and drift out into space for pennies per pound...

And you want their opinion on a possible competitor system?

Granted REL has their own issues but if you want an "outside" opinion you'd need to get one from someone who's probably at least in theory qualified to actually give you an accurate answer wouldn't you think?

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 04/05/2016 10:36 pm
The scramjet research and the people involved have no sensible bearing on space launch, so why the hell ask them to comment on SABRE?

Scramjet researchers may be biased.  But so might the people at REL.  Scramjet researchers are experts on propulsion at these speeds.  There's basically just them and REL.  Both could potentially have some bias, but if you want a perspective from outside REL, there's nobody better to give it than scramjet researchers.

Whether the goal is space launch or missiles, it's still propulsion at hypersonic speeds.

So, it makes sense to be wary of what scramjet researchers say about Skylon, and keep a critical frame of mind, but not to dismiss it out of hand.

Actually I have to disagree because SCramjet researches have a biased opinion BECAUSE SABRE is somewhat of a "hypersonic" propulsion system which therefore is directly in competition with them and they are pretty vocal about it. Yes REL has some bias' about SCramjets, so does anyone who's ever worked on or built subsonic combustion ramjets, including the majority of folks who initially worked the hardest ON SCramjet research.
(The same folks that actually BUILT operational ramjets all the way into the '90s before SCramjet research managed to convince everyone that ramjets were obsolete)

And ask yourself if you really get any good information from someone who has never researched or worked on anything BUT SCramjets on systems they therefore know nothing about? (Hint? While yes aero-propulsion systems are generally the same the devil is in the details and the people you're talking to in fact don't really know that much about anything BUT SCramjet propulsion)

The point, and it's quite a valid one, is that asking someone who works on SCramjets about a zero-to-hypersonic propulsion system is going to get you a vary biased and probably highly inaccurate answer because the person you're asking ONLY works with hypersonic to VERY-HIGH hypersonic propulsion and not anything that can start from zero and even go supersonic let alone reach hypersonic speeds on it's own. And you're asking the question of someone who very well knows that any positive answer can potentially cause their own research to lose funding, support, or interest.

SABRE barely touches hypersonic speed, (at most Mach-6 when "hypersonic" is at least Mach-5) it uses a compressor, it has rocket engines, and it takes off from a runway all of which a SCramjet doesn't do and frankly no one has been designing them to for almost 40 years. SCramjet researchers have all been concentrating on getting from Mach-7, (where a SCramjet starts working efficiently if at all) to higher speeds, the closest they have come in the last 20 years to addressing the "zero-to-" issue is suggesting an integral rocket/ramjet/SCramjet but since the 'duel-mode' SCramjet (a subsonic and supersonic combustion ramjet in one engine) never panned out and SCramjet research has sucked up all the money for integral rocket/ramjet research there has been nothing else but to launch SCramjet test articles by brute force rocket launch. Yet the same folks will tell you how wonderful the "theory" is that once we have SCramjets we can "easily" fly to Mach-26+ in the atmosphere and drift out into space for pennies per pound...

And you want their opinion on a possible competitor system?

Granted REL has their own issues but if you want an "outside" opinion you'd need to get one from someone who's probably at least in theory qualified to actually give you an accurate answer wouldn't you think?

Randy

Except what LM is looking into longer term for its air breathing vehicle isn't a pure scramjet.

Quote
Hewson also showed an image of a third hypersonic concept, similar to the HAWC but with a recoverable “turbine-based combined cycle” engine, Weiss explained. The HAWC’s booster is designed for a single use, he stressed. There is not yet a DARPA project for this capability, and Lockheed still needs to mature the propulsion technology, he said.

http://www.defensenews.com/story/defense/air-space/2016/03/16/lockheeds-marilyn-hewson-touts-breakthroughs-hypersonic-weapons/81836070/

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 04/05/2016 11:09 pm

Can't disagree. As Space X, as I imagine it, didn't went to investors telling them "we want to colonize Mars somewhere 30-50 years down the road. Wanna give us few hundreds millions?" Space X goal is hard and then rarely even talked about. All focus is on next step, which in SX case is to make cheap space transport.
They didn't go to investors at all Musk was rich enough to fund F1 and F9.

REL have had to justify every penny they have been given.
Quote
And here for REL they should/are focusing on engine. And if there is a way to generate revenue out of this engine then that's the way to go no matter if payer idea makes sense. If someone want to makes cats go to Internet faster using this engine let them do it if he pays btw for what REL guys and we all dream about :p
A fair point.
Musk wasn't rich enough, in fact he had to borrow money after the first three F1s blew up to fund the launch of the 4th and Spacex been borrowing money ever since.

But he had enough connections that he borrowed money of his rich silicon valley buddies, many of them I suspect thought it would just be fun to see if he could do it rather than as a series investment opportunity.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: oddbodd on 04/05/2016 11:11 pm

Except what LM is looking into longer term for its air breathing vehicle isn't a pure scramjet.


If you follow the thread back I was the original person criticizing the article - that was only about Skylon - for quoting the opinions of scramjet researchers. The article (http://forum.nasaspaceflight.com/index.php?topic=36826.msg1508669#msg1508669) had nothing to do with LM except for referencing the LM X-33 program that never flew and was canceled some 15 years ago. No-one else mentioned LM, so I don't understand the relevance of your point/response to Randy, which I guess relates to the proposals for their new SR-72 program engines. I only seek enlightenment btw, not trying to start a flame fest.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 04/06/2016 02:31 am

Except what LM is looking into longer term for its air breathing vehicle isn't a pure scramjet.


If you follow the thread back I was the original person criticizing the article - that was only about Skylon - for quoting the opinions of scramjet researchers. The article (http://forum.nasaspaceflight.com/index.php?topic=36826.msg1508669#msg1508669) had nothing to do with LM except for referencing the LM X-33 program that never flew and was canceled some 15 years ago. No-one else mentioned LM, so I don't understand the relevance of your point/response to Randy, which I guess relates to the proposals for their new SR-72 program engines. I only seek enlightenment btw, not trying to start a flame fest.

The article seemed pretty balanced between Skylon optimists and skeptics to me.  There were lots of quotes from a REL representative, and the non-Skylon people expressed a mix of skepticism and hope.  It was not a Skylon-bashing article.

If there are two main approaches, A and B, in any field, then the people working in the field who don't think A is the best approach will naturally be working on approach B.  Your argument seems to be that we should ignore all statements by people working on approach B.  I think that causes you to miss the opportunity to hear from the people most likely to have valid criticisms of approach A.  Sure, be aware that people working on B might have some bias, but listen and consider what they say, don't just dismiss it out of hand.  Unless, of course, you only want to hear opinions that confirm what you already believe.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 04/06/2016 06:43 am
I'd suggest that people don't usually work on a particular project because they've expertly assessed all the options and chosen what they think is the best one.  They are more likely to favour an approach (and/or have a dim view of alternatives) because it's what they've been working on their whole careers, since long before they had the expertise to assess the options.

If these scramjet guys had expressed valid concerns, that would be one thing.  But as far as I can tell from the article's quotes, there was no substance to their skepticism at all.  A bit of generic information about why SSTOs have been hard to build, and how you make engineering decisions when designing one, but no actual analysis or reasoning to support their negativity on the subject of Skylon specifically.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: MIKKELH on 04/06/2016 09:38 am
Please forgive me if this has already been discussed, but I ven't had the time to read all the 77 pages of posts in this thread, let alone the previous threads. I have my own reservations about Skylon, not because it is not pausible, nor even because the economic model won't work. Rather, I tend to agree with the argument that they are not thinking incrementally enough. It is not so mich that they are tacklong too many unknowns... It is that they are not taking a good look at what their engine actually does. Skylon is not really a novel engine design. It is at most a novel arrangement of engine omponents. What IS new is that rather than carrying pre-processed oxidizer in a heavy tank, they are collecting and processing oxygen as they go up. Personally, I think this is brilliant, but they are spending too mich time looking at other things.
Why not stick with basic, well proven, rocket engine designs? For the most part, this is all the thrust producing part of a Saber engine actually is. They have a collection of small conventional thrust chambers and nozzles, which is rather silly because these small thrusters are much less efficient than a single thruster with the same thrust load would be.
Why not stick with a proven booster design? Okay, a horizontal lift rocket would have the benefit of being able to use unsophisticated airport runways.... You just need to add LH propellant storage facilities. But, for the short term, stick with rockets that get out of the atmosphere more quickly... And thus reduce the total deltas v loss resulting from aerodynamic and gravity drag.
Finally, instead of developing an engine that produces just the right amount of oxygen flow as it is needed, and weighing down your rocket with the oxidizer mass required for operations when the atmosphere is too rarified for collection, why not stick with an oversized air collector and processor? Instead of solid rocket boosters, have strap on air collectors capable of processing large quantities of air, extracting water vapour centrifugally before comprssion, cooling the remaining air down to liquid temperatures ( condensation issues no longer being a major development concern because you are no longer feeding the processed oxygen in directly) during the compression stage, and feeding the liquid air (perhaps after separating the oxygen from the nitrogen centrifugally) to an initially empty propellant tank (initially loaded with just enough gaseous oxygen to support sea level air pressure). The key is to have a large enough intake not only to collect the amount of oxygen required for combustion, but to also fill the oxidiser tank while on the way up. Once at an altitude too high for oxygen collection, these strap on units will be jettisoned for recovery. Not only does this dramatically decrease launch mass, it also means that you can jettison the mass of the air intakes and compressors. As a side note, the extracted water and nitrogen could either be jettisoned directly, or collected in another 'empty' tank for space station supply.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 04/06/2016 02:32 pm
US military to reveal Skylon-based launch vehicle

http://www.rocketeers.co.uk/node/4613
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 04/06/2016 02:53 pm
US military to reveal Skylon-based launch vehicle

http://www.rocketeers.co.uk/node/4613

Can't see anything new in that, that hasn't already been reported up thread?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: MIKKELH on 04/06/2016 04:03 pm
What IS new is that rather than carrying pre-processed oxidizer in a heavy tank, they are collecting and processing oxygen as they go up

They're not. SABRE is not a LACE
SABRE is an evolutional development of LACE. The principal responsible for SABRE was co-creator of LACE, and all the work on SABRE was a continuation of the lessons learnt from LACE research. The essential difference between the two is that LACE liquified the oxygen, whereas SABRE keeps the oxygen above the condensation point, which I have already alluded to. There is also a difference in the intended structural design of the host craft (Skylon vs HOTOL) in that the engines are moved forward to correct for a cascade of problems resulting from the original engine placement causing the CG to be moved too far back.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: ChrisWilson68 on 04/06/2016 05:54 pm
US military to reveal Skylon-based launch vehicle

http://www.rocketeers.co.uk/node/4613

You make it sound like they're about to pull a curtain back and show the world an operational vehicle that is ready to fly.

I think it's more accurate to say "A US military research lab is going to present a paper outlining a two-stage launch vehicle concept using SABRE engine technology."

There's a big difference between SABRE-based and Skylon-based.  And there's a big difference between presenting a concept for a vehicle and unveiling an actual vehicle, or even a funded vehicle development program.

The truth of this is a big positive for REL.  No need to exaggerate.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: oddbodd on 04/06/2016 06:11 pm

Except what LM is looking into longer term for its air breathing vehicle isn't a pure scramjet.


If you follow the thread back I was the original person criticizing the article - that was only about Skylon - for quoting the opinions of scramjet researchers. The article (http://forum.nasaspaceflight.com/index.php?topic=36826.msg1508669#msg1508669) had nothing to do with LM except for referencing the LM X-33 program that never flew and was canceled some 15 years ago. No-one else mentioned LM, so I don't understand the relevance of your point/response to Randy, which I guess relates to the proposals for their new SR-72 program engines. I only seek enlightenment btw, not trying to start a flame fest.

The article seemed pretty balanced between Skylon optimists and skeptics to me.  There were lots of quotes from a REL representative, and the non-Skylon people expressed a mix of skepticism and hope.  It was not a Skylon-bashing article.

If there are two main approaches, A and B, in any field, then the people working in the field who don't think A is the best approach will naturally be working on approach B.  Your argument seems to be that we should ignore all statements by people working on approach B.  I think that causes you to miss the opportunity to hear from the people most likely to have valid criticisms of approach A.  Sure, be aware that people working on B might have some bias, but listen and consider what they say, don't just dismiss it out of hand.  Unless, of course, you only want to hear opinions that confirm what you already believe.

I have no problem with a countering view point, I'm just not convinced of the scramjet researchers as particularly good ones. A scramjet is (at least currently as far as I'm aware) a single mode engine more related to a pure jet (not turbine jet). If the article had quoted counterpoints from LACE, turbine jet, and/or rocket engine researchers/designers they would have made better skeptics. Instead only scramjet researchers were quoted, and as 93143 said, they weren't particularly good as skeptics.

Anyway, I think the horse is well and truly flogged on this.

[edited to remove the unintentional scamjet Freudian slip typo ;D]
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/06/2016 06:17 pm
What IS new is that rather than carrying pre-processed oxidizer in a heavy tank, they are collecting and processing oxygen as they go up

They're not. SABRE is not a LACE
SABRE is an evolutional development of LACE. The principal responsible for SABRE was co-creator of LACE, and all the work on SABRE was a continuation of the lessons learnt from LACE research.
Who are you talking about? HOTOL was not a LACE system.
Quote
The essential difference between the two is that LACE liquified the oxygen, whereas SABRE keeps the oxygen above the condensation point, which I have already alluded to. There is also a difference in the intended structural design of the host craft (Skylon vs HOTOL) in that the engines are moved forward to correct for a cascade of problems resulting from the original engine placement causing the CG to be moved too far back.
What exactly is the question you were asking?

US military to reveal Skylon-based launch vehicle

http://www.rocketeers.co.uk/node/4613

Can't see anything new in that, that hasn't already been reported up thread?
No. TL:DR version. LM say they've made lots of improvements to make a hypersonic weapon system. Please give us the money to build one.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/06/2016 06:22 pm
And there's a big difference between presenting a concept for a vehicle and unveiling an actual vehicle, or even a funded vehicle development program.
True.

LM continues their PR campaign to get build an "SR72," whatever that is.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: oddbodd on 04/06/2016 06:29 pm
SABRE is an evolutional development of LACE. The principal responsible for SABRE was co-creator of LACE, and all the work on SABRE was a continuation of the lessons learnt from LACE research. The essential difference between the two is that LACE liquified the oxygen, whereas SABRE keeps the oxygen above the condensation point, which I have already alluded to. There is also a difference in the intended structural design of the host craft (Skylon vs HOTOL) in that the engines are moved forward to correct for a cascade of problems resulting from the original engine placement causing the CG to be moved too far back.

Huh? Maybe it's a language thing, but co-creator? It reads a bit like you are saying the same person who came up with LACE also came up with SABRE, which is not true. I think it is a lost-in-translation thing though. Yes, the SABRE learnt from the lessons of LACE, but they are substantially different. AIUI LACE is a single mode engine that collects and uses/stores liquid oxygen (discarding the 80% nitrogen) before powering out of the atmosphere meaning it has to cruise in atmosphere for some period of time to collect sufficient oxygen. SABRE is a dual-mode engine that uses atmospheric gaseous oxygen/nitrogen while in-atmosphere and ground loaded on-board liquid oxygen for the exit from the atmosphere, which means it does not need to cruise along collecting oxygen. I'd call SABRE a cousin rather than progeny of LACE.

LACE was never an option for HOTOL, so not sure why you bring up the difference between HOTOL and Skylon here. The RB545 was designed for HOTOL, and is still classified top secret. I'd love to know what the big deal was with that engine.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 04/06/2016 07:17 pm
What IS new is that rather than carrying pre-processed oxidizer in a heavy tank, they are collecting and processing oxygen as they go up

They're not. SABRE is not a LACE
SABRE is an evolutional development of LACE. The principal responsible for SABRE was co-creator of LACE, and all the work on SABRE was a continuation of the lessons learnt from LACE research. The essential difference between the two is that LACE liquified the oxygen, whereas SABRE keeps the oxygen above the condensation point, which I have already alluded to. There is also a difference in the intended structural design of the host craft (Skylon vs HOTOL) in that the engines are moved forward to correct for a cascade of problems resulting from the original engine placement causing the CG to be moved too far back.

Note on the historical "evolution" of the SABRE cycle and LACE in general;

Alan Bond created a series of LACE and LACE-like engines but LACE itself was researched and developed in the United States in the mid-50s for the "Aerospaceplane" project. LACE, (Liquid Air Cycle Engines) have always suffered from a high "wastage" of hydrogen required in order to liquefy air to feed into the rocket engine. The air was turned to liquid because of a basic assumption that it HAD to be liquid to allow it to be compressed by a high-speed turbo pump to reach a high enough pressure to feed into a rocket combustion chamber. (Secondarily to allow it to be stored in on-board tanks to feed afore mentioned rocket engines later in flight)

Around the same time the first actual liquid hydrogen rocket engines were being developed and tested and several things were noted. First of all "liquid" hydrogen engines actually performed better if the hydrogen was injected as a high pressure "gas" rather than a liquid and second that the previously assumed "required" pressures in the combustion chamber had been over-estimated by a large factor. Lastly that if both the oxygen and hydrogen were injected as gasses mixing and combustion was much more efficient.

Unfortunately the people who were developing the rockets were not talking to those developing LACE and vice-versa in any significant way. So many of the basic assumptions that were directing the design of LACE development were in fact wrong.

During this time a sub-contractor on the Aerospaceplane LACE system discovered that highly cooled air, (very cold but NOT liquefied) could be compressed and pumped by modified turbo-pumps that were compatible with use in a rocket engine BUT did not reach the pressures that the teams developing LACE were assuming were required so deep-cooling as it was know was not pursued and eventually both LACE and Aerospaceplane were dropped. (Of course another down-side is "deep-cooled" air wasn't as efficient to store as LOX but that was actually "minor" since it was a "silly" idea to use "deep-cooled" air in a rocket engine when you needed LIQUID oxygen... Yep, dropped the ball there guys :) )

Several improvements on the basic concept of LACE came along over the years but pretty much all of them ended up using more liquid hydrogen than they actually needed to run the engine cycle because of the delta-t needed to go from "deep-cooled" to "liquid" so most work concentrated on methods of "using" that excess hydrogen.  LH2 turbofans, turbojets, and ramjets all burning the "excess" hydrogen were considered, researched and eventually discarded over and over again until Bond re-/discovered the idea of a deep-cooling rocket engine.

The situation is very much one of those historical "Doh!" moments when the answer was sitting right in front of everyone but missed because the "right" answer everyone knew was in fact not as "right" as was assumed.

And probably even MORE annoying than the history of the subject is the fact that after HOTOL was proposed but was having other issues, several OTHER people re-discovered the previous deep-cooled cycle work AND the fact that there had been tests running an RL10 on "deep-cooled-but-not-liquid" oxygen/air done in the late-60s/early-70s! Worse, "officially" everyone was assuming the reason HOTOL 'failed' was because the engines didn't work!

There are none so blind....

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/06/2016 07:31 pm
Huh? Maybe it's a language thing, but co-creator? It reads a bit like you are saying the same person who came up with LACE also came up with SABRE, which is not true. I think it is a lost-in-translation thing though. Yes, the SABRE learnt from the lessons of LACE, but they are substantially different. AIUI LACE is a single mode engine that collects and uses/stores liquid oxygen (discarding the 80% nitrogen) before powering out of the atmosphere meaning it has to cruise in atmosphere for some period of time to collect sufficient oxygen. SABRE is a dual-mode engine that uses atmospheric gaseous oxygen/nitrogen while in-atmosphere and ground loaded on-board liquid oxygen for the exit from the atmosphere, which means it does not need to cruise along collecting oxygen. I'd call SABRE a cousin rather than progeny of LACE.

LACE was never an option for HOTOL, so not sure why you bring up the difference between HOTOL and Skylon here. The RB545 was designed for HOTOL, and is still classified top secret. I'd love to know what the big deal was with that engine.
"William Escher" of NASA is often mentioned relevant to LACE. He came up with a way of describing most (all ?) air breathing space launch systems, which is why SABRE can be described as a "Deeply pre-cooled turbo rocket." Wheather he can be described as the inventor of LACE, as I suspect several companies had this idea around the same time.

I don't think there's any evidence he was in contact with any of the REL team.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 04/06/2016 08:33 pm
Except what LM is looking into longer term for its air breathing vehicle isn't a pure scramjet.

Quote
Hewson also showed an image of a third hypersonic concept, similar to the HAWC but with a recoverable “turbine-based combined cycle” engine, Weiss explained. The HAWC’s booster is designed for a single use, he stressed. There is not yet a DARPA project for this capability, and Lockheed still needs to mature the propulsion technology, he said.

http://www.defensenews.com/story/defense/air-space/2016/03/16/lockheeds-marilyn-hewson-touts-breakthroughs-hypersonic-weapons/81836070/

Actually no, LM is NOT looking into "long-term" and the concepts ARE in fact "pure" SCramjets... As we've been saying over and over again SCramjets need another engine system to reach operational speed. That's quite clear from the article. Note also that it clearly states LM needs to "mature" the propulsion technology, (ie: getting a SCramjet to actually work on a consistent basis) and that there are currently NO DARPA requirements for the concept vehicles.

Fun facts from the cited article;
- Lockheed is NOT working on any of the propulsion systems, that's Aerojet-Rocketdyne if they don't go out of business first.

- Both primary and secondary projects are in fact for "one-shot" weapons system with no "long-term" use. It is only when you get to a third "concept" vehicle they even mention a "reusable" turbine-based-combined-cycle BOOSTER for the one-shot SCramjet weapon.

- The article keeps pointing out that Lockheed (and the military) are aiming for speeds "up-to" Mach-5 which is barely hypersonic AND where we already know SCramjets have a hard time operating. (The speed is actually LOW for a supersonic internal engine flow, point-of-fact SUBSONIC combustion ramjet engines were lab-tested to speeds as high as Mach-7+ with "positive thrust-to-weight" factors HIGHER than tested SCramjets. Engineers who actually designed and built subsonic combustion ramjets stated they saw no problems other than materials in one going as fast as Mach-10. So one probably SHOULD question why everyone seems to think you need a SCramjet to do the job being described)

- Love the quote: “We are now producing a controllable, low-drag, aerodynamic configuration capable of stable operations from takeoff to subsonic, transonic, supersonic and hypersonic, to Mach 6.” Which sounds great until you realize the hypersonic flight portion has to take place at altitudes above 75,000ft or the airframe burns up.

- The "perspective" of a jet flying at Mach 5 "could cross the continental United States in about half an hour" is deceptive because said hypersonic jet is above 70,000ft where as the weapon needs to survive flying at that speed long enough to hit the target which will be well below 20,000ft! TPS requirements are going to make orbital reentry look like a campfire in "perspective" and the weapon has to survive that for probably a couple of minutes at least. (@Mach-5=3,600mph=60mpm=6mps. Hint: Russia is set to deploy an "long-range" AAA missile with a range of up to around 25 miles. To reach if from beyond effective range, say 30 miles to be generous the weapon has to survive for over 30 seconds at very low altitude and very high speed assuming the target is stationary mind you. CEP for a good kill on an armored target will be less than 100' and probably closer to 50' with a "standard' warhead including the weapon velocity)

Oh and I should mention the article is wrong, the X-15 went to Mach-6, (Mach-6.7 in fact which is faster than the SCramjet has gone) in the 1960s, not Mach-5 as stated.

Take away? LM is still trying to sell the idea of the "SR-72" in some fashion and are willing to turn it into a single use "prototype" weapon for the government if said government will fund them to the tune of a couple of billions dollars for ONE copy. Ignore the facts they have no engine, no aerodynamics, thermal or control systems since we're using the "Skunk-works" to propose this you should simply believe us when we say we can do what we haven't managed to do yet with the money you gave us already.

Oh and about nothing to do with the Skylon I should point out :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 04/06/2016 08:48 pm
Huh? Maybe it's a language thing, but co-creator? It reads a bit like you are saying the same person who came up with LACE also came up with SABRE, which is not true. I think it is a lost-in-translation thing though. Yes, the SABRE learnt from the lessons of LACE, but they are substantially different. AIUI LACE is a single mode engine that collects and uses/stores liquid oxygen (discarding the 80% nitrogen) before powering out of the atmosphere meaning it has to cruise in atmosphere for some period of time to collect sufficient oxygen. SABRE is a dual-mode engine that uses atmospheric gaseous oxygen/nitrogen while in-atmosphere and ground loaded on-board liquid oxygen for the exit from the atmosphere, which means it does not need to cruise along collecting oxygen. I'd call SABRE a cousin rather than progeny of LACE.

LACE was never an option for HOTOL, so not sure why you bring up the difference between HOTOL and Skylon here. The RB545 was designed for HOTOL, and is still classified top secret. I'd love to know what the big deal was with that engine.
"William Escher" of NASA is often mentioned relevant to LACE. He came up with a way of describing most (all ?) air breathing space launch systems, which is why SABRE can be described as a "Deeply pre-cooled turbo rocket." Wheather he can be described as the

I don't think there's any evidence he was in contact with any of the REL team. I'm not sure he can be described as the inventor of LACE, as I suspect several companies had this idea around the same time.

Escher was working for Mardquart at the time and they were one of the companies doing the development of LACE, (as well as initial SCramjet research and advanced ramjet work) and he was interested in the "deep-cooling" effect. But only in the context of increasing the density of intake air for T/W purposes. He was still advocating LACE for the rockets, (and moved to SCram-LACE as a 'standard' later on) and only briefly mentioned using the "excess" hydrogen from the LACE process injected in the after-burner portion of the SES/RJ (Supercharged-Ejector-SCram/Ramjet) engine as part of the bypass system during LACE operations. Most of his "Spaceliner" engine systems used LACE collection up to speeds in excess of Mach-10 so you can guess why he found a 'significant excess' of hydrogen being produced :)

To address the cycle question, and so we're all on the same page, LACE uses liquid hydrogen to turn incoming air liquid. The air is separated into oxygen and nitrogen using a variety of methods, (usually the least complex and lighters are preferred but there are trade offs) with the nitrogen dumped and the now liquid oxygen being stored and/or used in a rocket engine to continue acceleration. Dozens of variations exist from "simply" collecting the lox while in subsonic flight to the afore mentioned supersonic/hypersonic collection and liquefying idea and everything in between.

A great number of people still get confused with the difference between LACE and SABRE since they see an air-intake at one end and rocket motors at the other. There's still a lot of people who think that if you have rocket engines then obviously you have to feed them LIQUID oxygen. On the other hand there are still a lot of EXPERTS that think the same thing so I think the confusion can be forgiven :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/06/2016 08:49 pm
Take away? LM is still trying to sell the idea of the "SR-72" in some fashion and are willing to turn it into a single use "prototype" weapon for the government if said government will fund them to the tune of a couple of billions dollars for ONE copy. Ignore the facts they have no engine, no aerodynamics, thermal or control systems since we're using the "Skunk-works" to propose this you should simply believe us when we say we can do what we haven't managed to do yet with the money you gave us already.
That sounds less like the X30 (NASP) and reather more like the X33 for NASA.

That was for an SSTO (with the demo vehicle pitched to M15), cost $1.1Bn and delivered no flight vehicle.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 04/06/2016 09:07 pm
If you follow the thread back I was the original person criticizing the article - that was only about Skylon - for quoting the opinions of scramjet researchers. The article (http://forum.nasaspaceflight.com/index.php?topic=36826.msg1508669#msg1508669) had nothing to do with LM except for referencing the LM X-33 program that never flew and was canceled some 15 years ago. No-one else mentioned LM, so I don't understand the relevance of your point/response to Randy, which I guess relates to the proposals for their new SR-72 program engines.

It was supposed to show that "someone" working on SCramjets, (which LM actually isn't but a proposed weapon that would USE a SCramjet) is looking towards "long-term" use. Which is supposed to be connected to the use of "long-duration" in the article. The problem is that it is obvious that the article and LM were talking about a WEAPON system so "long-duration" is only enough time to go from launch to the target. (Which at Mach-5 you are talking seconds probably and less than a minute at best)

This IS a key point because what nobody mentions is that while a SCramjet has flown at hypersonic speed, (Mach-5.1 to be exact) it was at 60,000ft and what they military wants is something that can fly at Mach-5 from 20,000ft to ZERO feet! (It's a weapon after all) The SR-71 operated at speeds of Mach-3+ BUT only over 45,000ft, (closer to 65-70Kft actually) because it would fall apart at lower altitude from the heating.

What the military wants is something that can be launched from around 20,000ft to Mach-5 and then REMAIN at Mach-5 all the way to impact and zero feet. That's a key factor to keep in mind. What is required is a combined propulsion system as everyone keeps pointing out. What I find interesting is that LM and everyone else seem to be missing the point though. Yes a SCramjet can keep a vehicle at hypersonic speed (barely it seems) once its brought there by another propulsion system, but SCramjets, and ramjets actually work LESS efficiently as you decrease the altitude at higher speeds, (specifically hypersonic) because your aero-heating goes up significantly fast.

In essence what is being suggested by the requirements is a weapon that can be launched from beyond engagement range of the target defenses, accelerates to Mach-5 then SUSTAINS that speed until it "engages" the target and keeps that speed all the way to impact.

Nobody asks me but it's pretty clear that what you need is NOT a SCramjet but a boosted ramjet (expendable solid booster, dropped once the ramjet comes online) to Mach-5 at 20,000+ft, "cruise" to engagement range of the target, (the faster the better which is where a Mach-6-8 ramjet would come in handy, point is you need to keep a significant T/W which we already know the SCramjet can't do), lock on to target and expend the ramjet and light up another solid rocket to boost till target impact. Rather simpler and probably cheaper than a "billion dollars" since we've already built and flown integral rocket/ramjet missiles to over Mach-5 (albeit because of a stuck fuel valve but that's kind of makes my point) and all you're adding is another short-duration, high thrust rocket motor.

I'm going to leave this link here (http://www.designation-systems.net/dusrm/app4/asalm.html) and simply say this weapon was designed to fly at Mach-4.5 with a fixed inlet ramjet to a range of 300 miles (480km) with inertial and duel mode active guidance, (ok we'd lose the thermonuclear warhead but I'm not seeing that as a real "down-side" given the mission) in 1980... Explain to me again why LM (and everyone else) seems to think there's an urgent need for the SCramjet engine to meet the requirements?

Quote
I only seek enlightenment btw, not trying to start a flame fest.

Oh sure, you're an enabler and you know it ;)
Hope I helped explain things somewhat.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 04/06/2016 09:26 pm
Take away? LM is still trying to sell the idea of the "SR-72" in some fashion and are willing to turn it into a single use "prototype" weapon for the government if said government will fund them to the tune of a couple of billions dollars for ONE copy. Ignore the facts they have no engine, no aerodynamics, thermal or control systems since we're using the "Skunk-works" to propose this you should simply believe us when we say we can do what we haven't managed to do yet with the money you gave us already.
That sounds less like the X30 (NASP) and reather more like the X33 for NASA.

That was for an SSTO (with the demo vehicle pitched to M15), cost $1.1Bn and delivered no flight vehicle.  :(

Actually the demo was not supposed to initially go faster than Mach-12, but very soon after LM got the contract this was reduced to Mach-10, Mach-8, Mach-7, I think you get the picture :)

If you read the article can I ask if you were as amused by the statement by LM that “Lockheed Martin has a legacy of making fast aircraft,” with no hint of irony in that they are only know for doing so, what, twice? (F-104 and SR-71) Both of which were expensive to operate and maintain? The Skunk works isn't anything like what it was when those were designed and built and nothing gives me confidence that LM can actually accomplish what they say they can despite trying to build on a legacy they no longer follow.

And again I specifically have to question why they wouldn't consider actually using technology and systems they already HAVE to fill this supposed "urgent" need? Asking for a billion dollars for a single prototype when they could probably deliver an operational system for the same amount makes me wonder if we shouldn't see if we can run some copper wiring around Kelly Johnsons body and take advantage of all that spinning he's doing for the greater good...
(Sorry that was tacky but true:( )

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 04/06/2016 10:05 pm
Actually the demo was not supposed to initially go faster than Mach-12, but very soon after LM got the contract this was reduced to Mach-10, Mach-8, Mach-7, I think you get the picture :)
I didn't recall the exact starter Mach number.

I certainly recall the gradually dropping Mach numbers where it got to (IIRC) "Single Stage to Colorado" at the end.
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If you read the article can I ask if you were as amused by the statement by LM that “Lockheed Martin has a legacy of making fast aircraft,” with no hint of irony in that they are only know for doing so, what, twice? (F-104 and SR-71) Both of which were expensive to operate and maintain?
Somehow I thought they'd made more M2+ aircraft.

The F104 seemed to need a blown flaps system like the BAC Buccaneer (with a few more operating issues) to handle takeoff and landing.

Not to mention their aggressive marketing campaign for F104.
Quote
The Skunk works isn't anything like what it was when those were designed and built and nothing gives me confidence that LM can actually accomplish what they say they can despite trying to build on a legacy they no longer follow.
They played that card with the X33. Worked with NASA, but the DoD would have better access to the actual results
Quote
And again I specifically have to question why they wouldn't consider actually using technology and systems they already HAVE to fill this supposed "urgent" need? Asking for a billion dollars for a single prototype when they could probably deliver an operational system for the same amount
I think you hit the nail when you pointed out the Skunkworks of today is not the outfit Kelly Johnson ran through the 40s,50s and 60s. It's goal is not to keep Lockheed design ahead of the field, it's to get a cashflow from who'll ever pay them regardless of wheather there are cheaper ways to solve the problem.  :(
Quote
makes me wonder if we shouldn't see if we can run some copper wiring around Kelly Johnsons body and take advantage of all that spinning he's doing for the greater good...
(Sorry that was tacky but true:( )
I'm quite a fan of novel clean energy concepts myself.  :)

I'd love to see what would happen if people just said "We'll give the SCramjet a break and just see what the best conventional ramjet we can build using the latest CFD and diagnostics to build a really good fixed geometry system." The rule of thumb has been 3 Mach numbers and maybe slowing the airstream to M0.3. Make it 5 Mach numbers (possibly by slowing air to say M0.9) and if the rocket can get them to M2 that's well into the hypersonic range already.

I'll note the key reason REL switch to rocket at about M5.5 is that (as they've pointed out numerous times) at that point the energy you loose in slowing down the airflow inside the duct you have to put back burning fuel. That may be pessimistic based on a conservative ramjet design rules used in the spill ramjet buners, but I doubt it's that conservative. 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Archibald on 04/07/2016 12:14 pm
Quote
I didn't recall the exact starter Mach number

Initially it was to be mach 15, but then it dropped to mach 12. Did they dropped further before cancellation ?
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 04/12/2016 03:25 pm
Reading this article may answer why REL has yet to see the investment promised by the UK government. It seems since the General Election the industry now faces a more sceptical government when it comes to space related activities.

http://spacenews.com/is-britains-5-year-space-investment-locomotive-running-out-of-steam/
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 04/12/2016 05:06 pm
Actually the demo was not supposed to initially go faster than Mach-12, but very soon after LM got the contract this was reduced to Mach-10, Mach-8, Mach-7, I think you get the picture :)
I didn't recall the exact starter Mach number.

I certainly recall the gradually dropping Mach numbers where it got to (IIRC) "Single Stage to Colorado" at the end.

Actually it was always "Single-Stage-To-New Mexico" from Utah which was the Air Force proposed (and accepted) flight profile. With some "reverse" trips included. It was funny because the site in Utah is ALSO called "White Sands" and it was very clear that the Air Force lost interest pretty much as soon as the contract was signed because they canceled all work on repairs and upgrades to the launch site around that same time.

Quote
I didn't recall the exact starter Mach number

Initially it was to be mach 15, but then it dropped to mach 12. Did they dropped further before cancellation ?

The program goal was given as initially to Mach-15 and was dropped to Mach-12 when the contract was signed. LM kept dropping the goal all the way to cancelation which was Mach-6, maybe, by the time of cancelation.


I'll note the key reason REL switch to rocket at about M5.5 is that (as they've pointed out numerous times) at that point the energy you loose in slowing down the airflow inside the duct you have to put back burning fuel. That may be pessimistic based on a conservative ramjet design rules used in the spill ramjet burners, but I doubt it's that conservative.

Key note: REL is talking about air slowed for use in a compressor/fan, not the bypass/ram air which you need to keep in mind. While the air in a subsonic ramjet has to be slowed to use the combustor actual engineers who designed, built and tested standard ramjets were confident that a subsonic combustion ramjet could be designed to work from Mach-2 to Mach-10 with ease. I'll also note the "rule-of-thumb" that is being cited for the "3 Mach Numbers" is normally for a FIXED inlet ramjet where as an adjustable intake/exhaust system is pretty much insensitive to such issues. Around Mach-7 you have to inject more fuel to keep accelerating but the actual amount is not as significant as it's made out to be by SCramjet advocates. From what I understand after Mach-10 the amount of shocks needed to keep the flow sub-sonic is mechanically difficult and generally not thought to be worth the effort. (Not for anything that one wants to reuse that is :) )

I though the temperature of the intake air also became a problem above this speed?

Above Mach-5 intake air just keeps getting hotter as it's shocked to subsonic speeds and compressed. SABRE helps a lot since it's still cooling the air with the HE system where as a standard subsonic ramjet doesn't have such a system but once you've got an airframe and engine system that can stand up to higher speeds your intake air temperature is less of a problem. Again, engineers who worked on ramjets were confident they could be used up to Mach-10... But they were honest that there wasn't an airframe out there that could do the same :)

Really there isn't much of a requirement for sustained travel at hypersonic speeds. Almost every 'cited' use is for niche uses that for the most part are single-use missions OR ones that are just "passing through" speeds over Mach-5.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 04/12/2016 05:14 pm
Reading this article may answer why REL has yet to see the investment promised by the UK government. It seems since the General Election the industry now faces a more sceptical government when it comes to space related activities.

http://spacenews.com/is-britains-5-year-space-investment-locomotive-running-out-of-steam/

Interesting and not actually unexpected. Governments have a tendency to make decisions based on bias' upon which they are elected, no matter how short-sighted those bias' are.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Archibald on 04/12/2016 05:29 pm
Quote
LM kept dropping the goal all the way to cancelation which was Mach-6

Oh damn, was it THAT worse ?  >:(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 04/12/2016 07:03 pm
Reading this article may answer why REL has yet to see the investment promised by the UK government. It seems since the General Election the industry now faces a more sceptical government when it comes to space related activities.

http://spacenews.com/is-britains-5-year-space-investment-locomotive-running-out-of-steam/

Interesting and not actually unexpected. Governments have a tendency to make decisions based on bias' upon which they are elected, no matter how short-sighted those bias' are.

Randy

My heart sunk on reading as it seems like the UK might return to the old status que when it comes to the industry. Which wouldn't bode well for any more flights involving Tim Peake.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 04/12/2016 08:46 pm
Quote
LM kept dropping the goal all the way to cancelation which was Mach-6

Oh damn, was it THAT worse ?  >:(

Well, you can think of them being ahead of the curve for DARPA's XS-1 project, sorta :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lk555 on 04/14/2016 05:58 pm
Has anyone got a record of where I can find the STERN results? There was definitely a paper published and I had it from somewhere on open access, but I have no idea where it has saved.

Any help would be fantastic.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 04/19/2016 03:04 pm
Has anyone got a record of where I can find the STERN results? There was definitely a paper published and I had it from somewhere on open access, but I have no idea where it has saved.

Any help would be fantastic.
this? http://enu.kz/repository/2011/AIAA-2011-5688.pdf

Editted to add:
or this http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=30547.0;attach=534797

Those were quite interesting to read.  The conclusions don't seem to be absolutely definitively in favour of E/D nozzles and they do mention a follow on STRICT programme to see what might be done to cope with the issue they found.   It would be rather interesting to know what came out of that but I havenot been able to find anything so far.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: R7 on 04/22/2016 03:24 pm
from the other thread:

Why are you dodging the point?  Skylon's tanks are very low pressure and are not load-bearing; it's the truss that matters.

Just out of curiosity; are Skylon tanks rated at 1 atm gauge pressure all the way to the orbit (absolute pressure inside tanks reduced as the ambient pressure drops on the way up) or do they cope with 2 atm absolute?
Tank pressure falls with altitude. After MECO the main tanks are vented as a safety precaution OMS/RCS/APU are driven off a separate set of tanks.

When ambient pressure drops to near vacuum do Skylon tank pressures drop to 1 atm absolute, during powered flight??
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 04/22/2016 07:52 pm
When ambient pressure drops to near vacuum do Skylon tank pressures drop to 1 atm absolute, during powered flight??

According to the ESA report, yes.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: R7 on 04/23/2016 06:23 am
Read elsewhere that the hydrogen is subcooled to 16K. If the tank pressure is reduced to 1 atm during flight then NPSH drops to about 0.7atm minus all the losses on the way to the pump inlet. The turbopump guy is not going to be very happy about this.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 04/23/2016 08:27 pm
Part of the subcooling is for pump design reasons.  The rest is so the vehicle can sit on the runway for two hours without venting.  And I imagine the densification doesn't hurt...  (Just realized I probably overestimated the amount of kerosene/LOX that would fit into the tank volume, though I suppose you could densify that too...)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 04/24/2016 04:53 pm
Mark Thomas will be a speaker at this conference in May:
http://www.aerosociety.com/Events/Event-List/2197/What-Price-Speed
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 04/25/2016 11:22 am
Mark Thomas will be a speaker at this conference in May:
http://www.aerosociety.com/Events/Event-List/2197/What-Price-Speed
May be we will get something new, they been quiet since December.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 05/11/2016 08:21 am
any progress of late? we would very much appreciate some update status from REL, if any REL-affiliated person is reading this...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/11/2016 12:10 pm
Read elsewhere that the hydrogen is subcooled to 16K. If the tank pressure is reduced to 1 atm during flight then NPSH drops to about 0.7atm minus all the losses on the way to the pump inlet. The turbopump guy is not going to be very happy about this.
Running the properties for H2 from the NIST data book

http://webbook.nist.gov/cgi/fluid.cgi?TLow=14&THigh=20&TInc=1&Applet=on&Digits=5&ID=C1333740&Action=Load&Type=SatP&TUnit=K&PUnit=atm&DUnit=mol%2Fl&HUnit=kJ%2Fmol&WUnit=m%2Fs&VisUnit=uPa*s&STUnit=N%2Fm&RefState=DEF

Give saturation conditions for H2 at 16K of 0.2atm.

I'd suggest REL have had ample time to model flow losses through the pipework and turbopump design has advanced somewhat since days of the RZ20 and J2.

[EDIT The ability to pump 2 phase LH2/GH2 was part of the J-2S programme so a stage could relight after a long period on orbit (by the end they'd cracked the valve sequencing necessary to maintain low enough back pressure on the pumps to dispense with the starter cartridges, opening the way to unlimited starts). Designs capable of pumping a 50% gas flow had IIRC been mfg. AFAIK the design reports are still in the NASA archives ]
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 05/11/2016 12:30 pm
At the moment I believe SABRE 3 is very thirsty and SABRE 4 is "obese"

Could this mean a SABRE 3.5 !
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: dror on 05/11/2016 02:44 pm
Part of the subcooling is for pump design reasons.  The rest is so the vehicle can sit on the runway for two hours without venting.  And I imagine the densification doesn't hurt...  (Just realized I probably overestimated the amount of kerosene/LOX that would fit into the tank volume, though I suppose you could densify that too...)

I didn't read this thread for a while,
Why do you mention kerosene in relation to Skylon?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 05/12/2016 01:15 am
Carryover from another thread:

http://forum.nasaspaceflight.com/index.php?topic=40066.msg1521829#msg1521829
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alf Fass on 05/12/2016 06:46 am
Carryover from another thread:

http://forum.nasaspaceflight.com/index.php?topic=40066.msg1521829#msg1521829



Meanwhile, much more "traditional" SSTO proposals can get similar or higher margins and less payload uncertainty with way fewer new technologies and a more reasonable development budget...

Analysis or citation please.  This statement is preposterous on its face.

Actually, if a Skylon vehicle used dense propellants, conventional high t/w rocket engines and was launched vertically, it would place somewhere between 2 and 4 times more payload into orbit for its empty weight (obviously swapping out the SABRE engines for rocket engines).  I've done this calculation for several different iterations of the published Skylon empty mass, so don't wish to bother to hunt up the link here on NASAspaceflight at the moment.  But using published info on Skylon anyone can repeat the calculation.

The calculation illustrates Skylon's real technical risk (beyond the engines working as planned).  No surprise, but its mass fraction is quite high, higher than I'd be comfortable proposing for a LOX-hydrocarbon vehicle, even VTOL.  It just looks low due to the larger amount of LH2 it employs.  But PMF calculations always must be normalized to propellant density, not weight, since that is the proper metric.

I wrote this 5 years ago:
Quote
After running through the mass numbers for Skylon that Reaction Engines offers, I'm left believing that they've got an engine that will theoretically get them to orbit in one stage, but only by them making unrealistic assumptions about the structural weight of the rest of the vehicle, total dry mass 53 tonnes, engine thrust 270 tonnes, engine T/W 14 therefore mass of engines ~19 tonnes, therefore mass of the rest of the vehicle ~34 tonnes. 34 tonnes for a winged vehicle that's 83 meters long, carries all its landing gear to orbit, it has a propellant volume around 1400^3 meters, it uses cryogenic propellants and it has to endure re-entry. I know they're promoting Skylon as having revolutionary construction materials and methods, but it seems to me they've had to make some excessively optimistic assumptions about the structural weight to get the numbers to come together  so they can continue with their pet project - the engines.

Looking at it another way: The combined propellant tank volume by my math (with a few assumptions on the current LH2:LOX ratio) would have enough volume to hold 500 tonnes of LH2/LOX at a 1:6 ratio, lets allow structural weight growth of 20% for the heavier take-off weight making structural wt 40.8 tonnes, 2 SSME's (or easily maintained equivalent) is + 6.4 tonnes, so total unladen weight is 47.2 tonnes, add a P/L of 15 tonnes and also the 500 tonnes LOX/LH2 and you get a take-off weight of 562.2 tonnes, at engine shut off weight is 62.2. Mo/M1 is 9.03, delta V at Ve 4500 m/s is 9907m/s.

While I was obviously too optimistic about the achievable exhaust velocity from SSME's lifting from the ground, I see no reasons in the rebuttals to Gary's comments to revise my skepticism of Skylon, that version of Skylon had a fuselage physically larger than an A380 that weighs less than 34 tons. Why aren't we building all out jet aircraft using the aeroshell that RE plans? Think of the fuel savings that could be had by cutting the weight of aircraft by over 50%!
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/12/2016 09:58 pm
While I was obviously too optimistic about the achievable exhaust velocity from SSME's lifting from the ground, I see no reasons in the rebuttals to Gary's comments to revise my skepticism of Skylon, that version of Skylon had a fuselage physically larger than an A380 that weighs less than 34 tons. Why aren't we building all out jet aircraft using the aeroshell that RE plans? Think of the fuel savings that could be had by cutting the weight of aircraft by over 50%!
So you don't really know anything, but you're sure the number have been fudged. Is that about it?

And you really can't figure out any reason all aircraft are made from this material?

Passenger aircraft don't have to deal with skin temperatures of 1100c. They can get by with Aluminum and composites. The skin material is likely to be more expensive and certainly has less usage history than either, so they won't use it as there is no compelling need for it.

You've also ignored the fact that such a lightweight structural concept maybe possible because LH2 has such low density and the load is quite evenly distributed within the whole fuselage.

Rather like a soda can, which weighs 11g and carries around 330g,  but can support at least nine more sitting on top of it. IE a load of 3.3Kg sitting on an 11g, a 300:1 payload to structure ratio.

But you can't scale that performance up. The problem plays to the strengths of the materials used to create a solution that seems to be impossible.

Much like Skylon's structural concept.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alf Fass on 05/13/2016 01:37 am
While I was obviously too optimistic about the achievable exhaust velocity from SSME's lifting from the ground, I see no reasons in the rebuttals to Gary's comments to revise my skepticism of Skylon, that version of Skylon had a fuselage physically larger than an A380 that weighs less than 34 tons. Why aren't we building all out jet aircraft using the aeroshell that RE plans? Think of the fuel savings that could be had by cutting the weight of aircraft by over 50%!
So you don't really know anything, but you're sure the number have been fudged. Is that about it?

I didn't say fudged, rockets on the drawing board often don't turn out to be as good as the designers hoped, you and I are both in the situation of not really knowing anything, you're just trusting that this paper plane will work as well as its promoters imagine.
Quote
And you really can't figure out any reason all aircraft are made from this material?

Passenger aircraft don't have to deal with skin temperatures of 1100c. They can get by with Aluminum and composites. The skin material is likely to be more expensive and certainly has less usage history than either, so they won't use it as there is no compelling need for it.

And you know these facts from what?
Quote
You've also ignored the fact that such a lightweight structural concept maybe possible because LH2 has such low density and the load is quite evenly distributed within the whole fuselage.

So the vehicle has bulkheads in it to keep the H2 load evenly distributed even when the acceleration of the vehicle would make it unevenly distributed?
Quote
Rather like a soda can, which weighs 11g and carries around 330g,  but can support at least nine more sitting on top of it. IE a load of 3.3Kg sitting on an 11g, a 300:1 payload to structure ratio.

And if an ant were as big as an elephant it could lift 10 tons
Quote

But you can't scale that performance up. The problem plays to the strengths of the materials used to create a solution that seems to be impossible.

Much like Skylon's structural concept.

If the light weight Skylon fuselage is possible, it will be easy enough to build the tanks with that system to get to orbit with a reusable SSTO vehicle carrying the same PL, with the same vehicle dry mass, by using just plain old rocket engines.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Elmar Moelzer on 05/13/2016 01:59 am
rockets on the drawing board often don't turn out to be as good as the designers hoped
Like?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alf Fass on 05/13/2016 02:15 am
rockets on the drawing board often don't turn out to be as good as the designers hoped
Like?

The Shuttle had growth problems throughout its development, wasn't it originally supposed to get 29.5 tons into LEO, but couldn't in practice?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 05/13/2016 04:04 am
So the vehicle has bulkheads in it to keep the H2 load evenly distributed even when the acceleration of the vehicle would make it unevenly distributed?

No, I don't think so.  Actually, I think he misspoke there; it's not "even" distribution as much as it is a particular distribution that makes the structural concept work.  (Note that to help maintain trim, they drain the rear tanks first.)

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If the light weight Skylon fuselage is possible, it will be easy enough to build the tanks with that system to get to orbit with a reusable SSTO vehicle carrying the same PL, with the same vehicle dry mass, by using just plain old rocket engines.

Skylon is a detailed design optimized for a specific load envelope and mixture ratio with hydrogen in the bulk of the volume and almost all the heavy stuff in the middle where the lift and thrust loads are.  You can't just hijack it for rocket mixture ratios, never mind different propellants or a different vehicle configuration, and expect the dry mass to stay the same.  Mark Hempsell already pointed this out (http://forum.nasaspaceflight.com/index.php?topic=24621.msg758619#msg758619).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alf Fass on 05/13/2016 08:22 am

If the light weight Skylon fuselage is possible, it will be easy enough to build the tanks with that system to get to orbit with a reusable SSTO vehicle carrying the same PL, with the same vehicle dry mass, by using just plain old rocket engines.

Skylon is a detailed design optimized for a specific load envelope and mixture ratio with hydrogen in the bulk of the volume and almost all the heavy stuff in the middle where the lift and thrust loads are.  You can't just hijack it for rocket mixture ratios, never mind different propellants or a different vehicle configuration, and expect the dry mass to stay the same.  Mark Hempsell already pointed this out (http://forum.nasaspaceflight.com/index.php?topic=24621.msg758619#msg758619).

Hudson says volume Hempsell says mass, how to choose, personally I'd start with volume and add in whatever reinforcing required to support the extra mass.

With "build the tanks with that system" I mean using the same truss system that's supposed to work so well for Skylon but used in a VTOHL configuration with the engines at the back, interestingly despite my earlier misgivings, Skylon's fuselage isn't hugely lighter in terms of mass ratio that the Shuttle ET, the big difference is the surviving re-entry bit.

Something with the ET's H2/LOX propellant and Skylon's structural mass/propellant ratio and reentry ability with the equivalent of 6 SSME's on the back end could do the round trip with a similar PL to Skylon.

SLWT mass: 26,500 kg
LOX mass: 630,000 kg
H2 mass: 106,000 kg
6 x SSME: 27,600 kg
Add in a bit for other: 6,000 kg*
Payload: 15,000

GLOW: 811,100 kg

Thrust at Lift off: 6 x 1860 kN = 11,160 kN
Orbital mass: 75,100 kg

M0/M1 10.8

Exhaust velocity: 3586 - 4430 m/s SL - vac,  average 4000 m/s?

Delta V: 9518 m/s.


* Other: wings, fins, giudance, landing gear (which would be far lighter than Skylon's in only having to support the landing of the propellant empty vehicle) payload compartment - all the things already included in Skylon's ~34,000 kg engineless weight.

If Skylon works, I credit it to its light weight yet still reusable structure, not the engines.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 05/13/2016 01:45 pm
Anyway,
I updated my calculations for Skylon's operators and producers business case with very, very conservative assumptions.

Assumptions for the operator:
Skylon acquisition price: 2.3 BN Eur.  per Unit (4x original REL value)
operation costs per flight: 10 M eur per flight (2X original REL value)
market price of similar launcher category: 40 M eur per flight (SpaceX F9-1R)
Nr. of total flights: 200 (as stated by REL)
lifespan: 30 years (as stated by REL)
With this conservative assumptions, each Skylon operator closes the business case with at least 3 launches per year over 30 years, i.e. 90 launches in total in 30 years.


Assumptions for the builder:
Skylon development costs: 20 bn Eur (about 25% higher than REL estimates)
of which:
            10 BN put forward by investors
            10 BN through loan financing at 5%-year interest rate.

SKylon production cost (per unit) 300 M (unknown value)
Skylon selling costs (2.3 BN *unit) (about 4X original value).

Now, financing: assuming that:
1)  50% of the total develpment cost of Skylon (10 BN) is financed through 5% annual interest rate
2) 2/3 of each unit sold go to reduce that debt burden, while 1/3 goes to investors
3) REL pulls out 1 new skylon each year once the production kicks off

then, it will take 8/9 years for REL to completely repay the original debt burden without disappointing the investors. The entire amount put upfront by the investors (the other 10 BN) will be repaid in total 11 years.


With these numbers, REL (or any producer) turns to profit if at least 11 skylons are built.

diffent assumptions:

1) 10% annual interest rate, 1 skylon produced per year: 11 years to fully repay debt, investors are paid off in 14 years
2) 10% annual interest rate, 2 skylon produced per year: 6 years to repay debt, 6 to repay investors
3) 5% annual interest rate, 2 skylon produced per year: 4 years to repay debt, 5 to repay investors

Concluding, we can consider that the quicker Skylon units are produced and built, the less expensive they become (because revenue can be used to repay part of the debt, therefore reducing the interest burden).
in turn, the pace Skylon units are built depend on the market absorption capacity. for 2 units per year to be built each year, the total skylon fleet would need to increase number of flights it does each year from 6 (3 per vehicle the first year) to 30 (still 3 per vehicle) the sixth year.

The flight pace would need to increase if the price per flight were to go below 40M per flight (which is the price of the best competitor).

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/14/2016 10:47 am
I didn't say fudged, rockets on the drawing board often don't turn out to be as good as the designers hoped, you and I are both in the situation of not really knowing anything, you're just trusting that this paper plane will work as well as its promoters imagine.
The topic of what design margins SABRESkylon has has been discussed at length on this thread.

What we know from Shuttle is that it's possible to go from no design base to a design (the SSME) that was within 3 secs of its Vacuum Isp target. IIRC SABRE would have to be 10s of seconds below it's rocket Isp and 100s of secs below its airbreathing Isp before Skylon would not be viable at its design masses. REL have also stated they are designing to international standards for fuselage weight growth so their design still works if it comes in 15% heavier than expected.
Quote
And you know these facts from what?
People have been learning how to work and use Aluminum alloys since the days of the Zeppelins. Every material has a much shorter usage history in the field. This is why both the French and the British opted to go with a Aluminum alloy for Concorde. That was viable at M2.2, not so at M3.
Quote
So the vehicle has bulkheads in it to keep the H2 load evenly distributed even when the acceleration of the vehicle would make it unevenly distributed?
Centre of Gravity (or "trim" as it's usually called in aircraft) is AFAIK SOP for all big aircraft such as the round the world Voyager, because other wise you need large control surfaces and/or large movements of those surfaces to make the vehicle change directions. But fast aircraft also have major Centre of Pressure shifts as they move through the Mach range. The B58 and Concorde certainly controlled the order and rate their tanks were used and I'd fully expect the SR71 and XB70 did as well.

Incidentally it's the location of the dead weight that matters, not tank stiffness, so pressure stabilization would not help this problem. People who design rockets have little understanding of this area as their brief is just to get the vehicle out of any atmosphere ASAP.
Quote
And if an ant were as big as an elephant it could lift 10 tons
Exactly. But I still find it a good yard stick to remind people there is what is possible (under certain conditions) and what people think is possible. Frequently the latter is very much less than the former.
Quote
If the light weight Skylon fuselage is possible,
Which it is, given the Wellington bomber was built with such construction. It's strong and light but was labor intensive to build in WWII.

I full expect that even fairly slow automation (operating 24/7) could build full fuselages and wing assemblies at an acceptable rate with much lower staff needs.
Quote
it will be easy enough to build the tanks with that system to get to orbit with a reusable SSTO vehicle carrying the same PL, with the same vehicle dry mass, by using just plain old rocket engines.
You appear to be conflating 2 separate idea.

The question "Can you build the fuselage at all" and "can you build the fuselage so it can take 100tonnes+ more weight," since that's an estimate of the LOX mass SABRE's save the vehicle having to carry.

The first is plausible.

The second is much less certain.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/14/2016 11:10 am
Anyway,
I updated my calculations for Skylon's operators and producers business case with very, very conservative assumptions.

Assumptions for the operator:
Skylon acquisition price: 2.3 BN Eur.  per Unit (4x original REL value)

Assumptions for the builder:
Skylon development costs: 20 bn Eur (about 25% higher than REL estimates)
This is a most interesting post but I think you're starting numbers are a bit off.

Despite being a UK company REL normally quote their development budget and Skylon pricing in US dollars, whcih I think ithe international standard for the launch services business.

IIRC their current development budget (including the Skylon Upper Stage) is $12Bn, that's 10.61Bn euros, so 25% higher would be about 13.27Bn. 20Bn Euros is about 88% higher. IIRC this is derived from the ESA cost model, which is very conservative, given it predicted the A380 cost to be about $3Bn higher than it actually was.

The LSE analysis performed for ESA used a price of $2Bn for a Skylon, which is about Bn1.77 Euros. Your figure is therefor about 30% higher than the LSE estimate, which I think was conservative to begin with.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 05/14/2016 02:44 pm
Anyway,
I updated my calculations for Skylon's operators and producers business case with very, very conservative assumptions.

Assumptions for the operator:
Skylon acquisition price: 2.3 BN Eur.  per Unit (4x original REL value)

Assumptions for the builder:
Skylon development costs: 20 bn Eur (about 25% higher than REL estimates)
This is a most interesting post but I think you're starting numbers are a bit off.

Despite being a UK company REL normally quote their development budget and Skylon pricing in US dollars, whcih I think ithe international standard for the launch services business.

IIRC their current development budget (including the Skylon Upper Stage) is $12Bn, that's 10.61Bn euros, so 25% higher would be about 13.27Bn. 20Bn Euros is about 88% higher. IIRC this is derived from the ESA cost model, which is very conservative, given it predicted the A380 cost to be about $3Bn higher than it actually was.

The LSE analysis performed for ESA used a price of $2Bn for a Skylon, which is about Bn1.77 Euros. Your figure is therefor about 30% higher than the LSE estimate, which I think was conservative to begin with.

I am aware I was extremely conservative. However, consider that prices were expressed in 2008 values, so inflation also is to be taken into account. Still, the numbers are higher than their own estimates precisely because I wanted to test whether the model is sustainable even in case of substantial costs overshots.

the verdict is that yes, it looks sustainable, as long as operators mantain an high price (spaceX 1R levels). If prices go substantially below, then each Skylon will need to launch much more frequently . The bottom price any commercial Skylon operator looks to be a price of 16M/flight, at the conditions they manage to fly it at least 7 times per year (for 30 years). this is the minimal condition to operate without losses. below that, the company is in red.
Ideally, if a Skylon operator would charge 25M/flight and fly 10 times per year, it would completely repay the investment in about 8-9 years, leaving  more than the half of the vehicle capaity for pure profit.
in that case, total expected revenue is about 5Bn in 18 years.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 05/14/2016 02:52 pm
A public operator willing to buy a Skylon to use as a public infrastructure would be able to charge as little as 10M/flight to keep it running, at the condition of writing off the initial investment (as it happens with nearly all public infrastructure projects, which are not done to create profit for the the State but to provide infrastructure).
personally, I believe that a State owning a Skylon and willing to charge only operating expenses to the customers would be able to give an incredible boost to its space industry.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Elmar Moelzer on 05/14/2016 03:46 pm
The Shuttle had growth problems throughout its development, wasn't it originally supposed to get 29.5 tons into LEO, but couldn't in practice?
The Shuttle is a special case to me and also only ONE example for this. You said "often". One is not "often".
If I was to take one, then I could use Falcon 9 which is now way beyond the original designs capabilities.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Jim on 05/14/2016 04:48 pm
The Shuttle had growth problems throughout its development, wasn't it originally supposed to get 29.5 tons into LEO, but couldn't in practice?
The Shuttle is a special case to me and also only ONE example for this. You said "often". One is not "often".
If I was to take one, then I could use Falcon 9 which is now way beyond the original designs capabilities.

A.  It applies to all rockets, not just shuttle, most fail to meet original specs.   And it applies Falcon 9 too

b.  There were upgrades left on the table to help the shuttle meet original requirements. 

c.  All vehicles have gone through upgrades.  Nothing new about that.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/14/2016 05:12 pm
I am aware I was extremely conservative. However, consider that prices were expressed in 2008 values, so inflation also is to be taken into account. Still, the numbers are higher than their own estimates precisely because I wanted to test whether the model is sustainable even in case of substantial costs overshots.
I see.
Quote
the verdict is that yes, it looks sustainable, as long as operators mantain an high price (spaceX 1R levels). If prices go substantially below, then each Skylon will need to launch much more frequently . The bottom price any commercial Skylon operator looks to be a price of 16M/flight, at the conditions they manage to fly it at least 7 times per year (for 30 years). this is the minimal condition to operate without losses. below that, the company is in red.
Ideally, if a Skylon operator would charge 25M/flight and fly 10 times per year, it would completely repay the investment in about 8-9 years, leaving  more than the half of the vehicle capaity for pure profit.
in that case, total expected revenue is about 5Bn in 18 years.
My cost modelling game reckons the with enough launches the customer price for an F9SR will converge to the replacement cost of the upper stage, the refurb costs and the profit SX charge.

Currently Shotwell reckons $3m in all in will cover refurb and the upper stage is somewhere around $17m. With a 20% gross profit margin that gives a price of $27m/launch.

SX will say that FH will be cheaper on a $/Kg basis and (in principal) have all lower stages fully recoverable, but the mission cost goes up a lot.

The interesting thing about a state buying a Skylon is that while it won't have the launch site restrictions of a 2000 Km missile range to drop stages over it will have exactly the same political restrictions. In that those payloads funded by governments or government controlled institutions will not be allowed to launch from certain countries and vice versa.

However Skylon is the only architecture that lets each state do that and still give the supplier a profit.

Of course if that state were someone like New Zealand I could imagine quite a lot of people would be happy to have their payload launched by "NZ Space."  :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Elmar Moelzer on 05/14/2016 06:40 pm
The Shuttle had growth problems throughout its development, wasn't it originally supposed to get 29.5 tons into LEO, but couldn't in practice?
The Shuttle is a special case to me and also only ONE example for this. You said "often". One is not "often".
If I was to take one, then I could use Falcon 9 which is now way beyond the original designs capabilities.

A.  It applies to all rockets, not just shuttle, most fail to meet original specs.   And it applies Falcon 9 too

b.  There were upgrades left on the table to help the shuttle meet original requirements. 

c.  All vehicles have gone through upgrades.  Nothing new about that.
Falcon 9 exceeded the original specs, from all we know. No one said that vehicles don't go through upgrades. Upgrades are fine. My point was that the OP said that rockets often don't meet their design capabilities. My point was that while it might happen, it is not often. They get there, at least after upgrades.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alf Fass on 05/14/2016 10:51 pm
The statistics I quoted 5 years ago are different to those I'm seeing today, most notably engine thrust, my original post had it at 270 "tons" thrust at a T/W of 14, wiki now has 2000 kN per engine, still at T/W of "up to 14"

That difference would mean an increase in engine weight from 19 tons to over 28 tons, empty weight is still given as 53.4 tons, so that shrinks non engine empty weight from 34 to 25 tons.

Maybe I've misinterpreted something, or maybe wiki's got it wrong, or maybe those growth problems are happening for Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alf Fass on 05/14/2016 11:14 pm
. . . They get there, at least after upgrades.

Or they don't and are abandoned.


Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 05/15/2016 08:38 am
The statistics I quoted 5 years ago are different to those I'm seeing today, most notably engine thrust, my original post had it at 270 "tons" thrust at a T/W of 14, wiki now has 2000 kN per engine, still at T/W of "up to 14"

That difference would mean an increase in engine weight from 19 tons to over 28 tons, empty weight is still given as 53.4 tons, so that shrinks non engine empty weight from 34 to 25 tons.

Maybe I've misinterpreted something, or maybe wiki's got it wrong, or maybe those growth problems are happening for Skylon.

You're using wiki as a source for something like this.....
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alf Fass on 05/15/2016 09:19 am
The statistics I quoted 5 years ago are different to those I'm seeing today, most notably engine thrust, my original post had it at 270 "tons" thrust at a T/W of 14, wiki now has 2000 kN per engine, still at T/W of "up to 14"

That difference would mean an increase in engine weight from 19 tons to over 28 tons, empty weight is still given as 53.4 tons, so that shrinks non engine empty weight from 34 to 25 tons.

Maybe I've misinterpreted something, or maybe wiki's got it wrong, or maybe those growth problems are happening for Skylon.

You're using wiki as a source for something like this.....

The Reaction Engines site seems to have a lot less details about Skylon and Sabre on it these days, I can confirm that as of May 2014 the Skylon dry mass and engine thrust are as Wiki states, the T/W for the engines isn't stated on the RE document I'm looking at, but hey, maybe they're working on it going up from 14 to 20, that would keep the engine weight under control  ::) .

http://www.reactionengines.co.uk/tech_docs/SKYLON_Users_Manual_Rev_2.1.pdf
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/15/2016 10:14 am
The statistics I quoted 5 years ago are different to those I'm seeing today, most notably engine thrust, my original post had it at 270 "tons" thrust at a T/W of 14, wiki now has 2000 kN per engine, still at T/W of "up to 14"

That difference would mean an increase in engine weight from 19 tons to over 28 tons, empty weight is still given as 53.4 tons, so that shrinks non engine empty weight from 34 to 25 tons.

Maybe I've misinterpreted something, or maybe wiki's got it wrong, or maybe those growth problems are happening for Skylon.
Or we could use the figures from V 2.0 of the Skylon Users Manual figures.

That has a GTOW of 325 Tonnes  with air breathing minimum thrust of 163 tonnes up to 407 tonnes and a rocket thrust of 407 tonnes.

Given this is a HTO vehicle thrust does not have to exceed mass. Typically GTOW for aircraft is 3x thrust. For Skylon it's about 2x thrust, given a substantially faster acceleration profile. 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alf Fass on 05/15/2016 10:28 am
The statistics I quoted 5 years ago are different to those I'm seeing today, most notably engine thrust, my original post had it at 270 "tons" thrust at a T/W of 14, wiki now has 2000 kN per engine, still at T/W of "up to 14"

That difference would mean an increase in engine weight from 19 tons to over 28 tons, empty weight is still given as 53.4 tons, so that shrinks non engine empty weight from 34 to 25 tons.

Maybe I've misinterpreted something, or maybe wiki's got it wrong, or maybe those growth problems are happening for Skylon.
Or we could use the figures from V 2.0 of the Skylon Users Manual figures.

That has a GTOW of 325 Tonnes  with air breathing minimum thrust of 163 tonnes up to 407 tonnes and a rocket thrust of 407 tonnes.

Given this is a HTO vehicle thrust does not have to exceed mass. Typically GTOW for aircraft is 3x thrust. For Skylon it's about 2x thrust, given a substantially faster acceleration profile.

Umm, yeah, it's TO speed is around 500 km/hr!
The figures you quote offer no explanation as to how TO weight can increase by 50 tons, engine thrust can increase by 48% and yet dry mass remains the same as it was in the earlier C1 version.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alf Fass on 05/15/2016 10:33 am
wiki now has 2000 kN per engine, still at T/W of "up to 14"


Maybe I've misinterpreted something, or maybe wiki's got it wrong, or maybe those growth problems are happening for Skylon.
I take it you failed to notice the "citation needed" note on the 14:1 statement in wikipedia's Skylon article?

Why would they not have a citation? Is it perhaps because with RE failing to provide a T/W ratio for the engines they've done the sensible thing and had to assume its the same as for the previous engine?

If you think that an air breathing engine as complex as Sabre is can have a thrust ratio as high as 20/1, which would be far higher than any turbojet, well . . .
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 05/15/2016 01:12 pm
Sabre 3 engine mass was 10870 kg for both engines, Sabre 4 isn't necessarily a heavier engine as it losses the frost control mass.
SABRE T/W is up to 14 over the air breathing mode as it varies with velocity and altitude, peeking around Mach 2. SABRE rocket mode is substantially higher thrust with a T/W of 28.
That's my understanding from the information we have available to us.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/15/2016 05:08 pm
I take it you failed to notice the "citation needed" note on the 14:1 statement in wikipedia's Skylon article?

Why would they not have a citation? Is it perhaps because with RE failing to provide a T/W ratio for the engines they've done the sensible thing and had to assume its the same as for the previous engine?

If you think that an air breathing engine as complex as Sabre is can have a thrust ratio as high as 20/1, which would be far higher than any turbojet, well . . .
Firstly AFAIK it doesn't need to be better than 14:1 to do the job. I don't think anyone has suggested 20:1 is needed.

Is this another of your "Well I don't know any better, but I'm sure it can't be possible" views then?

As it happens experimental turbojet lift engines in the 1960's for some VTOL designs had T:W ratios of 16:1. They had short continuous operating lives but they were expected to only be operating in horizontal to vertical flight transition, a period of minutes with plenty of recovery time during flight.

The ones I'm aware of were designed by Rolls Royce.

There's the common state of practice, the state of the art and the theoretical maximum based on physics and thermochemistry.

The 3 are very rarely close to each other.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alf Fass on 05/15/2016 06:49 pm
Sabre 3 engine mass was 10870 kg for both engines, Sabre 4 isn't necessarily a heavier engine as it losses the frost control mass.
SABRE T/W is up to 14 over the air breathing mode as it varies with velocity and altitude, peeking around Mach 2. SABRE rocket mode is substantially higher thrust with a T/W of 28.
That's my understanding from the information we have available to us.

Thanks, that makes more sense.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 05/15/2016 11:44 pm

SABRE T/W is up to 14 over the air breathing mode as it varies with velocity and altitude, peeking around Mach 2. SABRE rocket mode is substantially higher thrust with a T/W of 28.
That's my understanding from the information we have available to us.
Which SABRE? do you have a source?
Skylon user Manual 2.1 shows 2MN peak thrust for air breathing and 2MN thrust for rocket.




The manual is stating gross thrust but I was quoting net T/W which explains the difference. During rocket mode the net thrust is much higher as atmospheric drag is removed. I should have been clearer.

Just to correct myself, I stated the wrong rocket mode, a T/W of 28 is what SABRE 3 seems to have but SABRE 4 looks like it reaches a T/W of 35 during rocket mode.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 05/16/2016 12:14 pm
Britain to announce the location of its first spacesport after tomorrow.

http://www.parabolicarc.com/2016/05/15/reports-britain-announce-location-spaceport-wednesday/

I believe that the only suited for Skylon is CampbellTown, right?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 05/16/2016 03:17 pm
The EU has launched a public consultation on its 2030 Space Strategy.

It will inform the next EU Strategy on space to be developed next year, and also will lead allocation of EU resources.

You can freely participate here: https://ec.europa.eu/eusurvey/runner/SpaceStrategy

Don't forget to cite SABRE development as a priority :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 05/16/2016 07:56 pm
Britain to announce the location of its first spacesport after tomorrow.

http://www.parabolicarc.com/2016/05/15/reports-britain-announce-location-spaceport-wednesday/

I believe that the only suited for Skylon is CampbellTown, right?

I got a feeling it will be Newquay through. Cornwall is a economic deprive area so using a spaceport to drive investment make sense. I don't think it will the two scottish sites.

It will be interest to see if any backers are reveal tomorrow. Virgin Galactic, Reaction Engines or BAE Systems.
£150 million is a bit low for Skylon through, construction and modifications to the runway is likely to cost substantially more than that.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alpha_Centauri on 05/17/2016 10:36 am
The spaceport isn't directly related to Skylon in any way, it's about developing the UK space sector through space tourism (virgin galactic etc) and eventually potential for a small polar launcher. Of course REL may well make use of the site for small-scale testing.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 05/17/2016 03:50 pm
The spaceport isn't directly related to Skylon in any way, it's about developing the UK space sector through space tourism (virgin galactic etc) and eventually potential for a small polar launcher. Of course REL may well make use of the site for small-scale testing.

I wouldn't say they are not related in any way. Sure, they are not dependent on each other. But a appropriately sized space-port would actually boost skylon chances.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alpha_Centauri on 05/17/2016 04:22 pm
Skylon, if it ever happens, will not launch from the UK.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/17/2016 06:49 pm
Skylon, if it ever happens, will not launch from the UK.
The UK is a possible site for polar launches, which would probably be adequate for most if not all of the test flight campaign, unless you needed to test the full mass to LEO, when you'd need an equatorial runway.

So if the site does have the right kind of runway for a fully loaded takeoff you could do most of the development work and building in the UK.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 05/17/2016 07:04 pm
Skylon, if it ever happens, will not launch from the UK.
But should it ever happen the government would very much like it to be built here which would require a runway capable of supporting at the very least self ferry launches to actual launch sites, which practically speaking would mean all the same requirements as the proposed spaceport.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: rcoppola on 05/17/2016 07:10 pm
The spaceport isn't directly related to Skylon in any way, it's about developing the UK space sector through space tourism (virgin galactic etc) and eventually potential for a small polar launcher. Of course REL may well make use of the site for small-scale testing.

I wouldn't say they are not related in any way. Sure, they are not dependent on each other. But a appropriately sized space-port would actually boost skylon chances.
The only thing that will boost Skylon's chances is finding a few Billion Dollars in development and testing costs. Which I hope they do.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 05/17/2016 11:04 pm
Skylon, if it ever happens, will not launch from the UK.
If it manufactured in the UK, it likely will be launched from the UK at least once and flown to its full time operating base.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alpha_Centauri on 05/18/2016 10:31 am
It is highly doubtful the majority of the manufacturing would be in the UK. No, it would be shipped in parts to be constructed on site.

The UK is a possible site for polar launches

Not with Skylon, that would be ridiculous. There are no payloads worth it lifting. As I said the plans are for polar launches with a small launcher, indeed REL discussed their own plan for such a vehicle, the hint being it's not Skylon...

As I said the spaceport isn't about Skylon, but they may use it for testing.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/18/2016 07:18 pm
The only thing that will boost Skylon's chances is finding a few Billion Dollars in development and testing costs. Which I hope they do.
The current round of development is looking for $360m.

What REL really need is a way to turn customer interest into a form that that can look to a bank like an order.

When you can take a binding agreement to a bank that says "We won't pay a penny up front but we'll pay the (inflation adjusted) price listed on it meeting the stated performance specifications" and have X potential customers signed up then funding gets easier.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 05/18/2016 07:26 pm
It is highly doubtful the majority of the manufacturing would be in the UK. No, it would be shipped in parts to be constructed on site.
building in the UK keeps the supply chain short and mostly paid in pounds. REL are not keen on "just returne." AFAIK they'd prefer to buy best-of-breed parts, not based on the proportion of funds from a country, hence their aversion to public funding.
Quote
Not with Skylon, that would be ridiculous. There are no payloads worth it lifting. As I said the plans are for polar launches with a small launcher, indeed REL discussed their own plan for such a vehicle, the hint being it's not Skylon...
My point was that while the UK is very far from being an ideal launch site for anything but polar launches that's would not be a problem for most of the Skylon test programme up to LEO flights but below full payload. You want to test if the vehicle can get to LEO, which inclination is not really that important.

It's when you want to go to a full payload LEO launch that you need a full weight runway near the equator.
Quote
As I said the spaceport isn't about Skylon, but they may use it for testing.
I don't think anyone thought it was.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Lars-J on 05/19/2016 07:22 am
Britain to announce the location of its first spacesport after tomorrow.

http://www.parabolicarc.com/2016/05/15/reports-britain-announce-location-spaceport-wednesday/

I believe that the only suited for Skylon is CampbellTown, right?

It may be somewhat ironic how they are planning a spaceport in an airport form, when the the real space launch growth in the near decades may be VTOL instead of HTOL. (the two reusable LV pioneers making the most current progress are VTOL: SpaceX and Blue, whereas the HTOL firms - VG, XCor, and Skylon - are facing severe technology or budget issues)

That could certainly change, but I would caution them to wait to make any sizeable spaceport investment, to avoid risking a "Spaceport America" situation.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 05/29/2016 10:44 pm
did someone go here?

http://www.aerosociety.com/Events/Event-List/2197/What-Price-Speed
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 05/29/2016 11:01 pm
just for your fun:

this  guy actually gave a presentation claiming that if Skylon can bring costs down to 200 $ kg to GEO (!!!) and fly about 140 times PER MONTH, then Solar-based power will make you rich.

He claims to work at REL, but it sounds suspicious because it clearly doesn't get the numbers right, and he puts his personal mail address (gmail) instead of the corporate one on the presentation.

https://drive.google.com/a/unitn.it/file/d/0B5iotdmmTJQsek9TNHhkeUI4UDlRQlNyVUNMclhJYkpxa3Jz/view
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: AnalogMan on 05/30/2016 01:30 am
just for your fun:

this  guy actually gave a presentation claiming that if Skylon can bring costs down to 200 $ kg to GEO (!!!) and fly about 140 times PER MONTH, then Solar-based power will make you rich.

He claims to work at REL, but it sounds suspicious because it clearly doesn't get the numbers right, and he puts his personal mail address (gmail) instead of the corporate one on the presentation.

https://drive.google.com/a/unitn.it/file/d/0B5iotdmmTJQsek9TNHhkeUI4UDlRQlNyVUNMclhJYkpxa3Jz/view (https://drive.google.com/a/unitn.it/file/d/0B5iotdmmTJQsek9TNHhkeUI4UDlRQlNyVUNMclhJYkpxa3Jz/view)


This tells you all you need to know:
https://en.wikipedia.org/wiki/Keith_Henson (https://en.wikipedia.org/wiki/Keith_Henson)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 05/30/2016 09:24 am
just for your fun:

this  guy actually gave a presentation claiming that if Skylon can bring costs down to 200 $ kg to GEO (!!!) and fly about 140 times PER MONTH, then Solar-based power will make you rich.

He claims to work at REL, but it sounds suspicious because it clearly doesn't get the numbers right, and he puts his personal mail address (gmail) instead of the corporate one on the presentation.

https://drive.google.com/a/unitn.it/file/d/0B5iotdmmTJQsek9TNHhkeUI4UDlRQlNyVUNMclhJYkpxa3Jz/view (https://drive.google.com/a/unitn.it/file/d/0B5iotdmmTJQsek9TNHhkeUI4UDlRQlNyVUNMclhJYkpxa3Jz/view)


This tells you all you need to know:
https://en.wikipedia.org/wiki/Keith_Henson (https://en.wikipedia.org/wiki/Keith_Henson)

you mean, for the scientology stuff?
otherwise the wiki page of the man doesn't transpire any particular weirdness,,, And I can tell you, those slides are full of it.

EDIT:
Ah, but YOU are the man, right? now I get it. And sorry, but the numbers just don't add up. How did you get to the 200$/KG to GEO cost?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 05/30/2016 10:10 am
just for your fun:

this  guy actually gave a presentation claiming that if Skylon can bring costs down to 200 $ kg to GEO (!!!) and fly about 140 times PER MONTH, then Solar-based power will make you rich.

He claims to work at REL, but it sounds suspicious because it clearly doesn't get the numbers right, and he puts his personal mail address (gmail) instead of the corporate one on the presentation.

https://drive.google.com/a/unitn.it/file/d/0B5iotdmmTJQsek9TNHhkeUI4UDlRQlNyVUNMclhJYkpxa3Jz/view (https://drive.google.com/a/unitn.it/file/d/0B5iotdmmTJQsek9TNHhkeUI4UDlRQlNyVUNMclhJYkpxa3Jz/view)


This tells you all you need to know:
https://en.wikipedia.org/wiki/Keith_Henson (https://en.wikipedia.org/wiki/Keith_Henson)

you mean, for the scientology stuff?
otherwise the wiki page of the man doesn't transpire any particular weirdness,,, And I can tell you, those slides are full of it.

EDIT:
Ah, but YOU are the man, right? now I get it. And sorry, but the numbers just don't add up. How did you get to the 200$/KG to GEO cost?
The logarithmic Skylon $/kg vs flights per year chart is from REL's own paper on Solar power sat manufacture. It shows a price point of 200$/kg at a flight rate of 9000 per year.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 05/31/2016 12:05 am
just for your fun:

this  guy actually gave a presentation claiming that if Skylon can bring costs down to 200 $ kg to GEO (!!!) and fly about 140 times PER MONTH, then Solar-based power will make you rich.

He claims to work at REL, but it sounds suspicious because it clearly doesn't get the numbers right, and he puts his personal mail address (gmail) instead of the corporate one on the presentation.

https://drive.google.com/a/unitn.it/file/d/0B5iotdmmTJQsek9TNHhkeUI4UDlRQlNyVUNMclhJYkpxa3Jz/view (https://drive.google.com/a/unitn.it/file/d/0B5iotdmmTJQsek9TNHhkeUI4UDlRQlNyVUNMclhJYkpxa3Jz/view)


This tells you all you need to know:
https://en.wikipedia.org/wiki/Keith_Henson (https://en.wikipedia.org/wiki/Keith_Henson)

you mean, for the scientology stuff?
otherwise the wiki page of the man doesn't transpire any particular weirdness,,, And I can tell you, those slides are full of it.

EDIT:
Ah, but YOU are the man, right? now I get it. And sorry, but the numbers just don't add up. How did you get to the 200$/KG to GEO cost?
The logarithmic Skylon $/kg vs flights per year chart is from REL's own paper on Solar power sat manufacture. It shows a price point of 200$/kg at a flight rate of 9000 per year.

A quite outdated paper I believe, as it does not match their own minimal numbers... would you mind to send me the reference paper?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 05/31/2016 12:37 am
just for your fun:

this  guy actually gave a presentation claiming that if Skylon can bring costs down to 200 $ kg to GEO (!!!) and fly about 140 times PER MONTH, then Solar-based power will make you rich.

He claims to work at REL, but it sounds suspicious because it clearly doesn't get the numbers right, and he puts his personal mail address (gmail) instead of the corporate one on the presentation.

https://drive.google.com/a/unitn.it/file/d/0B5iotdmmTJQsek9TNHhkeUI4UDlRQlNyVUNMclhJYkpxa3Jz/view (https://drive.google.com/a/unitn.it/file/d/0B5iotdmmTJQsek9TNHhkeUI4UDlRQlNyVUNMclhJYkpxa3Jz/view)


This tells you all you need to know:
https://en.wikipedia.org/wiki/Keith_Henson (https://en.wikipedia.org/wiki/Keith_Henson)

you mean, for the scientology stuff?
otherwise the wiki page of the man doesn't transpire any particular weirdness,,, And I can tell you, those slides are full of it.

EDIT:
Ah, but YOU are the man, right? now I get it. And sorry, but the numbers just don't add up. How did you get to the 200$/KG to GEO cost?
The logarithmic Skylon $/kg vs flights per year chart is from REL's own paper on Solar power sat manufacture. It shows a price point of 200$/kg at a flight rate of 9000 per year.

A quite outdated paper I believe, as it does not match their own minimal numbers... would you mind to send me the reference paper?
http://www.reactionengines.co.uk/tech_docs/ssp_skylon_ver2.pdf
It's page 23.  The chart actual refers to the flight rate of a second generation Skylon, it's assumed that  through operational learning a number of aspects have been improved lowering costs.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 05/31/2016 08:52 pm
this  guy actually gave a presentation

Yes he did; to REL on the date shown.

Quote
He claims to work at REL

Where does he claim this??

I've corresponded with Keith on a number of occasions and have found him sincere and serious, though perhaps over-ambitious (IMHO) to initiate and rapidly expand SSP at scale which undercuts coal. One thing I can be sure of (from my experience) is that he will have done the maths for both the physics and the economics before making any claims.

His plans include boot-strapping; using each SPS also for in-space beaming - to power arc jets to assist LEO-GSO transfer (faster transfer minimises micrometeorite and van-allen radiation damage) of further SPS.

REL have certainly offered support to him, though I wouldn't claim this extends to endorsement.

Keith has rarely commented on this forum: https://forum.nasaspaceflight.com/index.php?action=profile;area=showposts;u=13365 though I'm sure he would be willing to justify his claims (to someone with well-considered arguments) via the email address he supplied.



Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Keith Henson on 05/31/2016 10:55 pm
this  guy actually gave a presentation

Yes he did; to REL on the date shown.

Quote
He claims to work at REL

Where does he claim this??

To clear this up, I don't work for REL and don't know how anyone formed that impression from the slides.  It would be fair to call me a Skylon fan and a power satellite advocate.

Quote
I've corresponded with Keith on a number of occasions and have found him sincere and serious, though perhaps over-ambitious (IMHO) to initiate and rapidly expand SSP at scale which undercuts coal.

I don't like the huge scale either.  But if you want to solve the carbon and energy problems with power satellites, you are just stuck with it being huge.  Population size and power demand per person.

Quote
One thing I can be sure of (from my experience) is that he will have done the maths for both the physics and the economics before making any claims.

His plans include boot-strapping; using each SPS also for in-space beaming - to power arc jets to assist LEO-GSO transfer (faster transfer minimises micrometeorite and van-allen radiation damage) of further SPS.

It's a little more complicated.  The proposal is to build two propulsion power satellites up front and use those to reduce the cost for the LEO to higher orbits.  This video might make more sense than trying to explain it in words.

https://www.youtube.com/watch?v=VEkZkINrJaA

Shorter version that was shown a the White House recently by Peter Garretson and Paul Jaffe.

https://www.youtube.com/watch?v=zrcoD_vHzxU&feature=youtu.be

Quote
REL have certainly offered support to him, though I wouldn't claim this extends to endorsement.

Keith has rarely commented on this forum: https://forum.nasaspaceflight.com/index.php?action=profile;area=showposts;u=13365 though I'm sure he would be willing to justify his claims (to someone with well-considered arguments) via the email address he supplied.

If you set as a goal, power satellites cheap enough to displace coal, then you are limited to spending about $2400/kW.  Between parts, labor and the rectenna, that uses about $1100/kW.  The remaining $1300 is for transport.  Any combination of kg/kW and $/kg that comes in at $1300 or less will do.  I have proposed a thermal power satellite based on steam turbines and many square km of radiators that came in at 6.5 kg/kW, allowing up to $200/kg for the transport cost to GEO. 

BTW, the Skylon are expected to fly every other day.  140/month was the production rate of Skylons to keep up a million flights per year.  If you rebuild them at 500 flights, it would reduce the projection rate to 70/month.  The cost estimate graph mentioned in this thread gets down to $120/kg at around 100,000 flights per year.  The electric propulsion (at 30,000 tons per month) add about $55/kg to the cost.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 06/01/2016 03:29 pm
I don't like the huge scale either.  But if you want to solve the carbon and energy problems with power satellites, you are just stuck with it being huge.  Population size and power demand per person.

Sorry for reposting but I forgot to quote you in the approved way and don't want to be dumped out of the airlock as a result.

I wondered if the infrastructure for solar powered tugs might be useful for other launches? The scale of this enterprise seems great but I wondered if you might not use some of it to do other things and thus spread the cost a bit.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: MartinW on 06/02/2016 10:40 am
BTW, the Skylon are expected to fly every other day.  140/month was the production rate of Skylons to keep up a million flights per year.  If you rebuild them at 500 flights, it would reduce the projection rate to 70/month.  The cost estimate graph mentioned in this thread gets down to $120/kg at around 100,000 flights per year.  The electric propulsion (at 30,000 tons per month) add about $55/kg to the cost.
These are quite an absurd numbers, really. You'd need to have a multi-planetary species to support anything remotely near that number, it's such a high number for one launch vehicle to go that we are stepping into the realm of sci-fi. It's not feasible within a lifetime of any of us.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 06/02/2016 11:02 pm
BTW, the Skylon are expected to fly every other day.  140/month was the production rate of Skylons to keep up a million flights per year.  If you rebuild them at 500 flights, it would reduce the projection rate to 70/month.  The cost estimate graph mentioned in this thread gets down to $120/kg at around 100,000 flights per year.  The electric propulsion (at 30,000 tons per month) add about $55/kg to the cost.
These are quite an absurd numbers, really. You'd need to have a multi-planetary species to support anything remotely near that number, it's such a high number for one launch vehicle to go that we are stepping into the realm of sci-fi. It's not feasible within a lifetime of any of us.
For context both Airbus and Boeing routinely build more than 125 jet airliners per month  and there are easily more than 30 million airliner flights per year yet there are many people alive today for whom those numbers have come from nothing within their lifetimes.

Also I don't see how if a million flights a year are needed to build and support a global space solar power infrastructure off world colonies are needed to supply demand for that flight rate, the demand is the space solar power infrastructure which is what dictated the flight rate in the first place.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 06/03/2016 01:52 pm
Those of you who know my ID, know I am a huge fan of the Reaction Engine chaps. Thing is I am also a huge Elon Musk fan - and he says solar powered satellites are unnecessary. Being a huge REL fan for years I picked up on that comment straight away since I know of the old REL SPS study. In this video (at 3 minutes) he says, "If anyone should be in favour of solar power satellites it should be me ... but this is completely unnecessary"

https://www.youtube.com/watch?v=NvCIhn7_FXI
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 06/03/2016 04:03 pm
Those of you who know my ID, know I am a huge fan of the Reaction Engine chaps. Thing is I am also a huge Elon Musk fan - and he says solar powered satellites are unnecessary.

It's not as if his proposal is practical either at the moment  - I'm not buying solar panels for example because of the cost (installation, inverter etc).  It's actually a rip-off for those of us with small roofs where I live and I can save the planet more by buying a modern boiler.

One might as well work through these ideas for the sake of understanding them though and it can lead to other ideas.  e.g. a solar powered tug might be quite useful.

You might have a solar power station in orbit to power those micro-chip interstellar ships that Stephen Hawking etc have been talking about.  It could boost them up to near light speed.

Perhaps one day we will try to put up a sun shade to cool the earth down! :-)

Skylon will be at the ready to help make nutty ideas possible, crazy ideas imaginable.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 06/03/2016 04:09 pm
Those of you who know my ID, know I am a huge fan of the Reaction Engine chaps. Thing is I am also a huge Elon Musk fan - and he says solar powered satellites are unnecessary. Being a huge REL fan for years I picked up on that comment straight away since I know of the old REL SPS study. In this video (at 3 minutes) he says, "If anyone should be in favour of solar power satellites it should be me ... but this is completely unnecessary"

This is fairly old now, discussed here http://forum.nasaspaceflight.com/index.php?topic=30107.msg969044#msg969044 (Oct 2012) and more recently here http://forum.nasaspaceflight.com/index.php?topic=17902.msg1511703#msg1511703 (May 2016)

If you want to compare SPS with a relatively small scale terrestrial system located in the desert of your choice then I'd agree with Musk, with the caveat that his fabled photon-to-electron-to-photon-to-electron dismissal is actually not that bad at all: space solar beats equatorial noon sun by 37%, the dc-(space)-to-microwave-to-dc-(grid) can be achieved with an efficiency of around 50%. Add in the fact that power is constant except for a few hours each equinox (compared with terrestrial day/night cycles and weather) then, on average, space solar produces about 11 times more energy than the equivalent terrestrial system.

If your goal is to wean humanity off fossil fuels, then your options are limited. Take the (not-so-sunny) UK for example. Terrestrial solar farms average approximately 10W/m^2. An equivalent grid-scale rectenna would be limited only by the safe-level central peak beam intensity of 250-350W/m^2 (one-quarter to one-third noon sunlight intensity), giving an average power density of 60W/m^2 - i.e. requiring only one-sixth the land area, which could remain dual use for growing crops.

Of-course if you are contemplating fully renewable energy (as opposed to sustainable energy including fission/fusion power), then almost everything other than SPS requires truly massive grid-scale storage to meet baseload requirements.

Once as a civilisation we decide we can no-longer live with fossil fuels, and probably before fusion can be scaled globally, we will need Skylon, or something very much like it, to achieve the high flight rates - costs be damned!
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: lkm on 06/03/2016 06:23 pm
Those of you who know my ID, know I am a huge fan of the Reaction Engine chaps. Thing is I am also a huge Elon Musk fan - and he says solar powered satellites are unnecessary. Being a huge REL fan for years I picked up on that comment straight away since I know of the old REL SPS study. In this video (at 3 minutes) he says, "If anyone should be in favour of solar power satellites it should be me ... but this is completely unnecessary"

This is fairly old now, discussed here http://forum.nasaspaceflight.com/index.php?topic=30107.msg969044#msg969044 (Oct 2012) and more recently here http://forum.nasaspaceflight.com/index.php?topic=17902.msg1511703#msg1511703 (May 2016)

If you want to compare SPS with a relatively small scale terrestrial system located in the desert of your choice then I'd agree with Musk, with the caveat that his fabled photon-to-electron-to-photon-to-electron dismissal is actually not that bad at all: space solar beats equatorial noon sun by 37%, the dc-(space)-to-microwave-to-dc-(grid) can be achieved with an efficiency of around 50%. Add in the fact that power is constant except for a few hours each equinox (compared with terrestrial day/night cycles and weather) then, on average, space solar produces about 11 times more energy than the equivalent terrestrial system.

If your goal is to wean humanity off fossil fuels, then your options are limited. Take the (not-so-sunny) UK for example. Terrestrial solar farms average approximately 10W/m^2. An equivalent grid-scale rectenna would be limited only by the safe-level central peak beam intensity of 250-350W/m^2 (one-quarter to one-third noon sunlight intensity), giving an average power density of 60W/m^2 - i.e. requiring only one-sixth the land area, which could remain dual use for growing crops.

Of-course if you are contemplating fully renewable energy (as opposed to sustainable energy including fission/fusion power), then almost everything other than SPS requires truly massive grid-scale storage to meet baseload requirements.

Once as a civilisation we decide we can no-longer live with fossil fuels, and probably before fusion can be scaled globally, we will need Skylon, or something very much like it, to achieve the high flight rates - costs be damned!

What SPS is uniquely good at is providing power to a place without having to physically and permanently install a billion dollars of capital investment in that place. So for things like forward operating bases, refugee camps or unstable nations power can be supplied on a temporary basis or without risking your capital investment on the ground. For these uses the actual cost of power production is very much less important as SPS is competing with non consumption not other forms of production.

 SPS could also spread the power market from a regional one to a continental one as a Satellite could chose where to beam its power on a moment to moment basis across a much larger area than conventional power production can shift power to meet demand.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Chris Bergin on 06/03/2016 06:34 pm
This thread is to do with Reaction Engines/Skylon. If you want to discuss satellites, start a new thread.

(Reacting to report to mod alerts......lots of them today)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 06/05/2016 03:22 pm
Guys, I am sorry to have brought the issue up. But to me it sounds really at odds with reality to make hypotheses on the opportunities given by building 140 Skylons per month when we are very far away from securing even only the first 10% of the development programme.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 06/06/2016 07:38 am
If there was a very great project, could Skylon be scaled up?  We know that scaling down is problematic.  Could you double the volume, add 2 more engines and then carry twice the payload?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: 93143 on 06/06/2016 10:16 am
http://forum.nasaspaceflight.com/index.php?topic=24621.msg735577#msg735577

Quote from: Hempsell
We have not seriously explored taking the SKYLON type vehicle up to the heavy lift class but the few “fun exercises” we have done have not shown any fundamental upper limit technically but the economics go to pot. Basically making the systems as small as possible while still capturing the main market (i.e. not small sats) throws the economic burden on to more launches (where reusables score) and off development cost and acquisition cost (where reusable suffer).

Sounds like a yes.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Turbinia on 06/07/2016 08:09 pm
I have just listened to the the latest Planetary Radio podcast which had a very interesting interview with Andy Weir who presented his vision for low cost access to space for people and freight and leading to an LEO space tourism industry. The kind of assumptions which Andy outlines in the interview seems to me to point directly at a Skylon type solution (No he didn't mention Skylon).

Anyway the podcast can be found here http://www.planetary.org/multimedia/planetary-radio/show/2016/0606-2016-contact-conference  (http://www.planetary.org/multimedia/planetary-radio/show/2016/0606-2016-contact-conference) [
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Turbinia on 06/07/2016 08:14 pm
RE my post above this is the correct link. Sorry it was my first post.

http://www.planetary.org/multimedia/planetary-radio/show/2016/0606-2016-contact-conference.html  (http://www.planetary.org/multimedia/planetary-radio/show/2016/0606-2016-contact-conference.html)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 06/07/2016 08:17 pm
http://forum.nasaspaceflight.com/index.php?topic=24621.msg735577#msg735577

Quote from: Hempsell
We have not seriously explored taking the SKYLON type vehicle up to the heavy lift class but the few “fun exercises” we have done have not shown any fundamental upper limit technically but the economics go to pot. Basically making the systems as small as possible while still capturing the main market (i.e. not small sats) throws the economic burden on to more launches (where reusables score) and off development cost and acquisition cost (where reusable suffer).

Sounds like a yes.
jongoff makes a good argument for scaling down to like ~3 tons LEO, then using refueling and a transfer stage to put those 3 ton payloads directly to GSO. That would be about equivalent to 5 tons GTO.

So I wonder if Skylon could halve the cost (and development time) if they went for a ~3 ton payload instead of 10-15.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/08/2016 12:55 am
http://forum.nasaspaceflight.com/index.php?topic=24621.msg735577#msg735577

Quote from: Hempsell
We have not seriously explored taking the SKYLON type vehicle up to the heavy lift class but the few “fun exercises” we have done have not shown any fundamental upper limit technically but the economics go to pot. Basically making the systems as small as possible while still capturing the main market (i.e. not small sats) throws the economic burden on to more launches (where reusables score) and off development cost and acquisition cost (where reusable suffer).

Sounds like a yes.
jongoff makes a good argument for scaling down to like ~3 tons LEO, then using refueling and a transfer stage to put those 3 ton payloads directly to GSO. That would be about equivalent to 5 tons GTO.

So I wonder if Skylon could halve the cost (and development time) if they went for a ~3 ton payload instead of 10-15.
Where does this refuelling come from? Skylon already has a Skylon Upper Stage to handle the GTO, which like Skylon is designed to be reusable.

Provided you don't hit the machinery or building limits (which impose step change costs) bigger is not that much more expensive, and hence smaller is not that much more cheaper.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Avron on 06/08/2016 01:03 am
Skylon already has a Skylon Upper Stage

six year later ...

... can you post a picture of this Skylon.. or at least a working air breathing rocket engine ?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 06/08/2016 01:12 am
http://forum.nasaspaceflight.com/index.php?topic=24621.msg735577#msg735577

Quote from: Hempsell
We have not seriously explored taking the SKYLON type vehicle up to the heavy lift class but the few “fun exercises” we have done have not shown any fundamental upper limit technically but the economics go to pot. Basically making the systems as small as possible while still capturing the main market (i.e. not small sats) throws the economic burden on to more launches (where reusables score) and off development cost and acquisition cost (where reusable suffer).

Sounds like a yes.
jongoff makes a good argument for scaling down to like ~3 tons LEO, then using refueling and a transfer stage to put those 3 ton payloads directly to GSO. That would be about equivalent to 5 tons GTO.

So I wonder if Skylon could halve the cost (and development time) if they went for a ~3 ton payload instead of 10-15.
Where does this refuelling come from? Skylon already has a Skylon Upper Stage to handle the GTO, which like Skylon is designed to be reusable.

Provided you don't hit the machinery or building limits (which impose step change costs) bigger is not that much more expensive, and hence smaller is not that much more cheaper.
Reduce the cost enough, and it looks attractive versus developing Ariane 6. Or, you know, let perfect be the enemy of the good and be content with nothing. If a reduction in payload from 15 tons to 3 tons means a reduction in cost to near Ariane 6 costs, then all of a sudden, Skylon looks very attractive.

And being much, much smaller would make operating out of more airports a LOT easier by reducing the infrastructure costs (hydrogen, etc) and reducing the required runway length. That'd dramatically expand the client base. That is Reaction Engines' business plan, right?


...a reduction of payload from 15 tons to 3 tons could result in a reduction in development costs from $12 billion to $4.5 billion. That is the same as Ariane 6.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Chris Bergin on 06/08/2016 11:58 am
Skylon already has a Skylon Upper Stage

six year later ...

... can you post a picture of this Skylon.. or at least a working air breathing rocket engine ?

Probably could have said it less sarcastically ;) But this really needs some progress now. If other vehicles are subject to questions, this one should be too. To me it feels like it's stuck in the mud somewhat. I'd "love it" if I could be proven wrong. Keegan-style (UK folk will get that reference).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 06/08/2016 12:32 pm
Skylon already has a Skylon Upper Stage

six year later ...

... can you post a picture of this Skylon.. or at least a working air breathing rocket engine ?

Probably could have said it less sarcastically ;) But this really needs some progress now. If other vehicles are subject to questions, this one should be too. To me it feels like it's stuck in the mud somewhat. I'd "love it" if I could be proven wrong. Keegan-style (UK folk will get that reference).

Of late I'd say it maybe that BAE who are steering the ship and they have other things in mind for technology than Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: supersubie on 06/08/2016 07:15 pm
Just saw that the USAF are expected to announce a development programmer based around the SABRE pre cooling technology later this year. Is this new information or just a continuation of the studies they have been working on together in the past?

http://nextbigfuture.com/2016/06/us-air-force-research-will-develop.html
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 06/08/2016 07:18 pm
Just saw that the USAF are expected to announce a development programmer based around the SABRE pre cooling technology later this year. Is this new information or just a continuation of the studies they have been working on together in the past?

http://nextbigfuture.com/2016/06/us-air-force-research-will-develop.html

I am sure this was initially reported a little while back. This is pretty intriguing & probably will finally represented some  full scale forward momentum for REL.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/08/2016 07:47 pm
Just saw that the USAF are expected to announce a development programmer based around the SABRE pre cooling technology later this year. Is this new information or just a continuation of the studies they have been working on together in the past?

http://nextbigfuture.com/2016/06/us-air-force-research-will-develop.html
The article still thinks this is for a LACE cycle.

That puts doubt on the rest of the article.  :(

Likewise if the USAFRL want a M5 engine, not a ground-to-space engine SABRE is a very odd choice to start from, as REL could have told them.

The whole "two-stage-is-easier-than-one" mantra is simple wrong if SABRE can demonstrate it's full capabilities.

It's like turning an E-type jaguar into a hearse.  :)

Possible, but why do so?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 06/14/2016 06:29 pm
Which is a shame, it would be nice to believe there was some weight behind this article where Nextbigfuture believes the Reaction Engine Skylon Spaceplane will be fully funded (http://nextbigfuture.com/2016/06/spacex-disrupting-global-space-industry.html) as a result of SpaceX's potential dominance

Don't read anything into NextBigFuture articles. It's just a one-man science blog. Outside of some conference-blogging, there's never new information in the articles. Certainly, in the case of space-related topics, nothing you wouldn't have seen on NSF.

The author is usually just regurgitating press releases, science papers, or trying to do an "overview" type of article from a handful of different (online) sources, sometimes with a mushing together of concepts. (The Skylon article seems to be an example of the latter.)

For regular readers, NextBigFuture is basically just having someone else trawl the net for science stories for you; summarised so you can see if you care enough to click-through to the primary source. You get used to the vagaries of the author.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/14/2016 09:57 pm
It may be easier to obtain funding for a new class of engine that can be strapped to an existing vehicle
What existing vehicle would that be? XS1 seems too far gone for them to be an entrant and ATK seem quite tightly linked into the SR72 powerpoints powerplant project
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than to punt for a novel engine for a novel vehicle which requires novel infrastructure? or to put it anouther way
Quote
AFRL officials views a single-stage-to-orbit Skylon space plane as "technically very risky as a first application [...]
This remains just a bizarre piece of logic. REL did an EU design study specifically for M5 cruise for the EU. While the core elements are similar the overall design is radically different because the task is radically different. The USAFRL should know this.

If the SABRE test engine delivers its promise the only logical thing to put it on is a single stage to orbit spaceplane. If you just want a precooled engine then it's not SABRE.

It comes down to this. A 2 stage design would essentially be the original Faget concept space shuttle (hopefully without the high risk stall maneuver he was looking at).

Such a design needs 2 engines and 2 airframes to get funded, develop and test.

There are a few ways to side step some of those issues, but not many.

Build the aircraft equivalent of a "biamese" rocket. 2 Identicalaircraft with the same engines and airframe.  SABRE sort of plays into this concept if your issue is you doubt REL's Skylon concept is infeasible. Note for maximum cost reduction the engines and airframes must be identical.

Slightly down from this would be identical airframes with different SABRE versions. The booster has the full moving spike inlets but flies with empty LOX tanks (remember, identical hardware --> both vehicles can be certified together) the upper stage has sealed nacelles (identical aerodynamics AFAP for flight certification)  and runs purely in rocket mode, with a reduced LH2 load. Same tanks, different propellant load. It's not the maximum payload to orbit plan, but it is the minimum budget plan short of the reprising the STS orbiter-plus-moster-RATO-packs-plus-monster-drop-tank concept, which we all got to appreciate.

Above that in terms of cost (and the most conventionally structured development plan) would be where you're looking at 2 separate vehicles (with separate mfg programmes, followed by separate then combined test programmes to integrate them together) with 2 separate engines.

Best case for this is that USAFRL has an existing rocket engine they can use for the 2nd stage. Worst case is this is a development from scratch.  :(

A TSTO is probably the safe bet if you don't have an engine that can give you (at least for part of the journey) an Isp of 3000+ secs.

Once that's on the table you should really reconsider your options.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 06/14/2016 11:59 pm
TSTO is the best bet if you don't want to solve the problems you're likely to uncover from both a dramatically new engine concept and an extremely good mass fraction airframe/TPS simultaneously.

One miracle at a time.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 06/15/2016 01:03 am
Note for maximum cost reduction the engines and airframes must be identical.

Incorrect. This is the two-is-more-than-one myth again. A single design that can perform the two tasks is not necessarily going to be cheaper to develop than two designs that do one each. In fact, given the demands of re-entry, the opposite is likely to be true. For a TSTO built around SABRE, a biamese may be the worse possible design possible.

And you certainly don't want to use the same engines on both stages (you don't want SABRE or a derivative on the second stage.)

Similarly,

Such a design needs 2 engines and 2 airframes to get funded, develop and test.

With a TSTO, the upper stage engine would be a conventional rocket engine. That will not be the same development costs as the first stage hybrid air-breathing engine. For the first experimental version of the system, you can even use a conventional upper-stage off an existing system. That reduces your development cost to just the first stage. Since the re-entry for the upper-stage is vastly more demanding than the first stage, deferring development of a reusable second stage saves a lot, and allows you to fly hardware sooner.

I'm not arguing that the USAF idea for TSTO is necessarily superior to Skylon, but two-is-more-expensive-than-one is not a valid argument against it.

[edit: corrected stupid]
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/15/2016 07:50 am
TSTO is the best bet if you don't want to solve the problems you're likely to uncover from both a dramatically new engine concept and an extremely good mass fraction airframe/TPS simultaneously.

One miracle at a time.
If SABRE fully checks out on the ground you'll basically waste most of it's design features. If you just want precooled air inlets then it's not SABRE at all. It's jet engine with a heat exchanger up front.

This should still generate significant revenue for REL, but it's not getting them anywhere near orbit.  :(

Regarding truss structure. NASA Langley did a study in 1969 comparing Aluminum with AlBe and Be tubing. The straight Al alloy structure (the "heavy" design) weighed 3lbs but could carry a 250lb load, roughly 83 1/3:1 load to mass.

So I think a well designed truss structure can support very significant loads.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/15/2016 07:51 am
Incorrect. This is the two-is-more-than-one myth again. A single design that can perform the two tasks is not necessarily going to be cheaper to develop than two designs that do one each.
Let me get this straight.

A TSTO using 2 unique stage designs and engines will be cheaper to design and build IE the overall budget will be lower, than a biamese with a single structural and engine design
Quote
In fact, given the demands of re-entry, the opposite is likely to be true. For a TSTO built around SABRE, a biamese may be the worse possible design possible.
No one goes to a biamese design for performance. They use it because the budget won't support the cost of 2 full vehicle and possibly engine design and the integration of the 2 vehicles, which might involve redesign as well. I did not state this but I thought it was fairly obvious.
Quote
With a TSTO, the upper stage engine would be a conventional rocket engine.
Which was noted as a possible development option if you have an engine of appropriate size, or one that can be clustered to give the necessary thrust or you are in the position to size SABRE to the upper stage engine ahead of time. So now you're down to SABRE and 2 unique vehicles.
Quote
That will not be the same development costs as the first stage hybrid air-breathing engine. For the first experimental version of the system, you can even use a conventional upper-stage off an existing system. That reduces your development cost to just the first stage. Since the re-entry for the upper-stage is vastly more demanding than the first stage, deferring development of a reusable second stage saves a lot, and allows you to fly hardware sooner.
So basically an XS1 done by the USAFRL.
Quote
I'm not arguing that the USAF idea for TSTO is necessarily superior to Skylon, but two-is-more-expensive-than-one is not a valid argument against it.
Ah, I see our grounds for disagreement.

I was looking at how to fly SABRE and deliver a fully reusable launch system. You merely want to stick a payload in orbit.

You seem to be under the impression there is a shortage of space launch systems.

There is not. 

What there is a shortage of are fully reusable launch systems (1 or 2 stage) so the only part that gets "expended" is the payload (and you have down mass), with a turnaround time from previous launch measured in (at most) weeks and with a time from request (assuming you have a payload to hand) to launch of days or hours that you can treat as an asset not a ticket to ride and that you can buy and sell as an asset.

That's something no one has. It's something quite a lot of payload people would like and it's something that SABRE can help supply.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alf Fass on 06/15/2016 08:04 am
TSTO is the best bet if you don't want to solve the problems you're likely to uncover from both a dramatically new engine concept and an extremely good mass fraction airframe/TPS simultaneously.

One miracle at a time.
If SABRE fully checks out on the ground you'll basically waste most of it's design features. If you just want precooled air inlets then it's not SABRE at all. It's jet engine with a heat exchanger up front.

This should still generate significant revenue for REL, but it's not getting them anywhere near orbit.  :(

Regarding truss structure. NASA Langley did a study in 1969 comparing Aluminum with AlBe and Be tubing. The straight Al alloy structure (the "heavy" design) weighed 3lbs but could carry a 250lb load, roughly 83 1/3:1 load to mass.

So I think a well designed truss structure can support very significant loads.

One thing that does worry me about the Skylon truss structure is something I saw in an interview with a crewman on the Wellington bomber, while he thought the framing was great, he recounted how flexible the Wellington's fuselage was, he said the plane virtually wriggled its way across the sky, with the fuselage continuously bending and twisting in flight.

I imagine that the designers of Skylon will have to engineer a far more ridged frame structure given the rigidity that I assume the aeroshell will have.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 06/15/2016 08:25 am
Incorrect. This is the two-is-more-than-one myth again. A single design that can perform the two tasks is not necessarily going to be cheaper to develop than two designs that do one each.
Let me get this straight.
A TSTO using 2 unique stage designs and engines will be cheaper to design and build IE the overall budget will be lower, than a biamese with a single structural and engine design

Yes.

It will also be faster to develop.

No one goes to a biamese design for performance.

No one goes to a biamese in reality.

You seem to be under the impression there is a shortage of space launch systems.

I'm not. The USAF wants a launcher that can operate out of airports and quickly replace US satellites in the event of a major kick-off with an a-sat capable nation.

Delta/Atlas/F9 ain't such beasts, and are vulnerable to attacks on launch sites.

And they obviously don't trust that Skylon can be built for a reasonable price or on a reasonable schedule.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/15/2016 11:41 am
One thing that does worry me about the Skylon truss structure is something I saw in an interview with a crewman on the Wellington bomber, while he thought the framing was great, he recounted how flexible the Wellington's fuselage was, he said the plane virtually wriggled its way across the sky, with the fuselage continuously bending and twisting in flight.

I imagine that the designers of Skylon will have to engineer a far more ridged frame structure given the rigidity that I assume the aeroshell will have.
AFAIK the wellington structure was a single shell. Skylons is a space frame, with 2 layers of members. I would expect it to be much more rigid to stop it contacting the tanks which occupy most of the space frame, rather than to cope with skin rigidity.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/15/2016 06:23 pm
Why would there be? We develop multistage rockets all the time. Something as sophisticated and high performance as Skylon and its airframe is FAR harder. It will be more expensive, by Reaction Engines' own estimates!
It seems I have not been clear enough on my assumptions.

My OP on this subject had the words

Quote from: john smith
Build the aircraft equivalent of a "biamese" rocket. 2 Identicalaircraft with the same engines and airframe.  SABRE sort of plays into this concept if your issue is you doubt REL's Skylon concept is infeasible. Note for maximum cost reduction the engines and airframes must be identical.
Emphasis added.

Being the USAF I expected they to be looking at a winged vehicle. SABRE is also a very poor fit to a VTO LV so no I would expect designing 2 large aircraft with very different designs to be very expensive.

It would seem people who only think in terms of cylindrical tanks, with nothing wrapped around them, have trouble adjusting to the concept.

Obviously I must take more care to spell exactly what I mean to ensure comprehension by all readers. 
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 06/16/2016 11:42 am
Alan Bond to be guest of honour at BIS summer get together on the 30 July.

http://www.bis-space.com/2016/01/18/16053/bis-space-conference-at-charterhouse
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: momerathe on 06/16/2016 02:16 pm
Why would there be? We develop multistage rockets all the time. Something as sophisticated and high performance as Skylon and its airframe is FAR harder. It will be more expensive, by Reaction Engines' own estimates!

IIRC REL actually addressed this directly at some point. Paraphrasing from memory, with a reusable TSTO there are actually three vehicles that need to be flight tested: the first  stage, the second stage, and the first and second stage together. This makes for a hard combinatorial problem. The flight dynamics of the Skylon airframe, OTOH are relatively bog-standard.

In other words, going TSTO might de-risk the engine, but it would add risk to the airframe development. Obviously they have confidence in their engine technology.

Rockets have significantly simpler flight dynamics and, moreover, there's a wealth of institutional knowledge on building multistage rockets that doesn't exist for aircraft.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 06/16/2016 03:37 pm
Yeah, I've heard that argument before, but Skylon is anything but bog standard.

I think Reaction Engines shouldn't let perfect be the enemy of the good, here. Far better to actually fly than to just talk about it because the initial investment step is simply far too high.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: momerathe on 06/17/2016 08:29 am
Well, AFRL have kindly offered to do that for them. :)

Less flippantly, what they really have to do is demonstrate a fully working engine - which is what they're working on. At that point any number of options open up.

I've somewhat lost track of the discussion - is the NTV still a thing?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/17/2016 09:12 am
Yeah, I've heard that argument before, but Skylon is anything but bog standard.
Only in areas where where it can't afford to be.  Most of it's construction techniques have been suggested or used in other contexts, such as MLI and truss structures. Even the water cooled brake idea is SOP (in truck racing). Key risks are more in the materials area and structural interaction over the whole M0-23-0 range.
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I think Reaction Engines shouldn't let perfect be the enemy of the good, here. Far better to actually fly than to just talk about it because the initial investment step is simply far too high.
Undoubtedly.

The problem is moving to a 2 winged stage design, which is needed for full reusability. Skylons in rocket mode already has the best possible Isp and if you're worried about the structural design AFAIK all other are worse, requiring more of the mass to be set aside for the structure. I think it's fair to say most of the benefits of staging in other designs are simply delivered by the high Isp of SABRE.

So if you can't design a 2nd winged stage with lower structural mass fraction than Skylon (the "safe" option because we're talking risk reduction here. Although at M5+ A lifting body design would be possible if you can figure out how to land it ) the only other option is the expendable rocket, IOW the XS-1 approach .

Note this is the broad outline of the constraints and it's possible that at the margins an option for a fully reusable 2 stage vehicle exists. Perhaps Skylons structural design is actually conservative compared to some other approaches, allowing a heavier structure for the 2nd stage, rather than the straight propellant-tanks-with-engines-at-bottom which seems the only lighter weight option.

Perceptions that a 2 stage winged system is somehow "safer" to design are just that, perceptions.
Once you see the constraint map I can't help thinking "Let's go for broke. See what the budget is, build the smallest SABRE you can and the smallest Skylon around it you can. It might put 10Kg in LEO but it's a) fully reusable and b)can be returned to Earth after it's been in orbit. "

This is still the USAF Research Laboratory. Research is about taking calculated risks. 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Asteroza on 06/20/2016 01:29 am
Following that train of thought, what are reasonable lower bounds on size for SABRE cycle designs, if you want to follow the minimum demo path with a mini-Skylon? What is the bricklifter equivalent, able to place a 3U cubsat in orbit? REL is loath to make anything less than full size, mostly due to LH2 turbine design issues, but AFRL is under no such constraint (though considering the recent demise of the air launch project again...)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/20/2016 09:45 am
Following that train of thought, what are reasonable lower bounds on size for SABRE cycle designs, if you want to follow the minimum demo path with a mini-Skylon? What is the bricklifter equivalent, able to place a 3U cubsat in orbit? REL is loath to make anything less than full size, mostly due to LH2 turbine design issues, but AFRL is under no such constraint (though considering the recent demise of the air launch project again...)
That is a very tough question to answer.

SABRESkylon is a system. If you shrink SABRE you have to think about the issues of shrinking Skylon.

REL do have a horror of scale models because they have scale effects, things that are highly non linear with size. The other issue is scaling up from test samples. Using small modules of large systems makes this much easier as much less analysis is going to be needed to do the scaling.

For SABRE I'd start by asking what is the smallest part of the engine already? The rest of the design I could scaled down by reducing the number of modules (and accepting the thrust loss as a consequence) but this part is either the smallest you can get or needs a major redesign to go smaller, possibly triggering module redesigns as well, giving a small engine with no pedigree you can use in the final version. It's no longer a SABRE-lite, with few key modules of every subsystem. It's a complete reimplementation of a SABRE at a smaller scale.  :(

But that scaling is likely the easy part.

Aerodynamic phenomena scale very badly. A 10-20cm nose radius may have relatively  low heating but drop that to a 2cm radius and the stagnation heating will skyrocket. What was viable in Pyrosic or RCC may not even be viable in the UHTC materials like Hafnium Diboride (assuming you could get big enough pieces that aren't too brittle and can be machined to adequate tolerances). Likewise transpiration cooling might need to cover a substantial part of the (model) wing due to boundary layer effects, which again scale badly.

Likewise they truss members are (IIRC) about 30cm long. You can make them shorter but you'd need to make them smaller in diameter so the end connectors remained a fraction of the link mass, but that fraction would be rising.

Essentially you would retain the aspect ratio of the payload bay but accept whatever the design can lift as the payload. I've no real sense how far you could go down with this plan.  Ithink the SABRE 4 cycle, needing lower thrust chamber pressures, helps a bit

Essentially it would be a very tricky re-balancing act, akin to the original SABRESkylon design process.

I'd love to see a fully orbit capable Skylon the size of a large executive jet. Once you demonstrate self ferry, launch on demand and rapid turnaround everything changes.

But I expect the physics places strong limits on how small you can make the airframe, and hence how small an engine is needed to fly the mission.

And I think those limits are pretty high.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Nilof on 06/20/2016 10:26 am
Yeah, I've heard that argument before, but Skylon is anything but bog standard.
Only in areas where where it can't afford to be.  Most of it's construction techniques have been suggested or used in other contexts, such as MLI and truss structures. Even the water cooled brake idea is SOP (in truck racing). Key risks are more in the materials area and structural interaction over the whole M0-23-0 range.
Quote
I think Reaction Engines shouldn't let perfect be the enemy of the good, here. Far better to actually fly than to just talk about it because the initial investment step is simply far too high.
Undoubtedly.

The problem is moving to a 2 winged stage design, which is needed for full reusability. Skylons in rocket mode already has the best possible Isp and if you're worried about the structural design AFAIK all other are worse, requiring more of the mass to be set aside for the structure. I think it's fair to say most of the benefits of staging in other designs are simply delivered by the high Isp of SABRE.

So if you can't design a 2nd winged stage with lower structural mass fraction than Skylon (the "safe" option because we're talking risk reduction here. Although at M5+ A lifting body design would be possible if you can figure out how to land it ) the only other option is the expendable rocket, IOW the XS-1 approach .

Note this is the broad outline of the constraints and it's possible that at the margins an option for a fully reusable 2 stage vehicle exists. Perhaps Skylons structural design is actually conservative compared to some other approaches, allowing a heavier structure for the 2nd stage, rather than the straight propellant-tanks-with-engines-at-bottom which seems the only lighter weight option.

Perceptions that a 2 stage winged system is somehow "safer" to design are just that, perceptions.
Once you see the constraint map I can't help thinking "Let's go for broke. See what the budget is, build the smallest SABRE you can and the smallest Skylon around it you can. It might put 10Kg in LEO but it's a) fully reusable and b)can be returned to Earth after it's been in orbit. "

This is still the USAF Research Laboratory. Research is about taking calculated risks.

You do NOT need wings or lifting bodies at all for reuse. Winged reentries are the root of all evil. Reducing peak g-loads and peak heating seems like a good trade at first, but it moves the heating problem to a near-equilibrium heating situation which forces you into a lot of bad trades that tend to increase shielding mass. Wings add mass, are useless for most of the flight, and add reentry problems that are arguably harder than the ones they solve.

I mean, which one would you rather do? Quickly pour a shot glass of liquid nitrogen on your hand, or keep it in -20C freezing salt water for a few hours? What kind of gloves would you need to protect your hand against one or the other?

Blunt-body reentry with high gees and ablative shielding add less mass than wings would. Lift is naturally much easier to get at high gees so maintaining the maximum load at the design level is easier. Any structural reinforcements required also give you more safety margin on the way up.

I would argue that three different wingless vehicles are much easier to design than a single winged vehicle that has to work from mach 0 to mach 25.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: momerathe on 06/20/2016 10:48 am
You do NOT need wings or lifting bodies at all for reuse.

No, but it cuts the required takeoff thrust by your L/D ratio. IIRC the SABRE thrust in airbreathing mode isn't enough for vertical takeoff, without scaling the engine up considerably.

Quote
I would argue that three different wingless vehicles are much easier to design than a single winged vehicle that has to work from mach 0 to mach 25.

Well yes, that's obvious. Is that actually what AFRL are proposing though?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Nilof on 06/20/2016 11:00 am
You do NOT need wings or lifting bodies at all for reuse.

No, but it cuts the required takeoff thrust by your L/D ratio. IIRC the SABRE thrust in airbreathing mode isn't enough for vertical takeoff, without scaling the engine up considerably.

But for TSTOs it gives you nothing. Liftoff T/W barely cuts into the dry mass that has to be brought with you into orbit at all.

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I would argue that three different wingless vehicles are much easier to design than a single winged vehicle that has to work from mach 0 to mach 25.

Well yes, that's obvious. Is that actually what AFRL are proposing though?

It is what the USAF will likely be contracting for standard workhorse launches in a few years, without any government R&D money required.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/21/2016 06:36 am
You do NOT need wings or lifting bodies at all for reuse. Winged reentries are the root of all evil. Reducing peak g-loads and peak heating seems like a good trade at first, but it moves the heating problem to a near-equilibrium heating situation which forces you into a lot of bad trades that tend to increase shielding mass. Wings add mass, are useless for most of the flight, and add reentry problems that are arguably harder than the ones they solve.
You seem to have a  design in mind. Perhaps you should move this discussion to a new thread?
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Blunt-body reentry with high gees and ablative shielding add less mass than wings would.
As Dyansoar and Hermes "proved."  :(

Yet the USAF has persisted with the X37b, whose wings are used only during descent.
As always in such a discussion such a statement has so many hidden assumptions behind it that it's virtually meaningless.
Quote
Lift is naturally much easier to get at high gees so maintaining the maximum load at the design level is easier. Any structural reinforcements required also give you more safety margin on the way up.
Don't you mean high velocity?
Quote
I would argue that three different wingless vehicles are much easier to design than a single winged vehicle that has to work from mach 0 to mach 25.
BTW After Mercury (which was designed for a pure ballistic entry) all US vehicles have generated aerodynamic lift as part of their trajectory.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: momerathe on 06/21/2016 10:51 am
You do NOT need wings or lifting bodies at all for reuse.

No, but it cuts the required takeoff thrust by your L/D ratio. IIRC the SABRE thrust in airbreathing mode isn't enough for vertical takeoff, without scaling the engine up considerably.

But for TSTOs it gives you nothing. Liftoff T/W barely cuts into the dry mass that has to be brought with you into orbit at all.

Why don't rockets have turbofan first stages, then? they've got great ISP..

Quote
Quote
I would argue that three different wingless vehicles are much easier to design than a single winged vehicle that has to work from mach 0 to mach 25.

Well yes, that's obvious. Is that actually what AFRL are proposing though?

It is what the USAF will likely be contracting for standard workhorse launches in a few years, without any government R&D money required.

What's that got to do with anything? I'll restate the question. Are AFRL proposing a SABRE-based, wingless, VTVL TSTO?

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 06/23/2016 05:47 pm
Opinion | Reviving The Aerospace Plane Program

Quote
The design of an aerospace plane strongly depends on the propulsion system. With successful ground and flight tests of the SABRE, it could be available for use in an aerospace plane in the 2020s, decades before the availability of appropriate turbine-based combined cycle (TBCC) engines [which are designed either with a turbine engine plus a dual-mode ramjet (or dual-mode scramjet) engine] for an accelerating atmospheric flight reaching Mach ~11. The USAF hypersonic roadmap projects technology readiness in the 2040s for a hypersonic cruise aircraft using a TBCC engine. Consequently, the first-generation operational aerospace planes would use SABRE and the second-generation planes would use TBCC engines.

http://spacenews.com/reviving-the-aerospace-plane-program/
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 06/23/2016 07:21 pm
Opinion | Reviving The Aerospace Plane Program
http://spacenews.com/reviving-the-aerospace-plane-program/
Read it. If you know the subject it's hilarious.  :)

Either this guy is an associate professor or he's with AIAA. You're not a professor with AIAA.



Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Archibald on 07/01/2016 03:19 pm
This is certainly sloppy. What aerospaceplane ? the one of the 60's ? the NASP of the 80's ? something else ? Skylon ? (there is a picture of Skylon, but nothing related in the writting)

It looks like someone having an epiphany and saying " hey, we need a RLV to make space transportation cheaper" That opinion is just 70 years old (and counting !)

(P.S is it just me or every single post in this thread related to Brexit have been cut, a complete week of messages ?!!  :o )
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 07/04/2016 11:04 am
BAE Systems have released a video of a single-engined Mach 5 vehicle which is clearly SABRE-derived:

https://www.youtube.com/watch?v=4OMAEEqORyY
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 07/04/2016 12:12 pm
Thanks for posting. I wonder who the intended audience is... As you say, it's clearly influenced by Skylon/SABRE, but I wonder if that influence is simply artistic/aesthetic.

(And I certainly hope we don't have to wait for those holographic projection screens to be developed before seeing some flying REL hardware!)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/04/2016 12:17 pm
Thanks for posting. I wonder who the intended audience is... As you say, it's clearly influenced by Skylon/SABRE, but I wonder if that influence is simply artistic/aesthetic.

(And I certainly hope we don't have to wait for those holographic projection screens to be developed before seeing some flying REL hardware!)

I imagine the intended audience is the USAF.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 07/04/2016 12:32 pm
I think this is the first stage of BAC starting to market the SABRE concept, they are big into military hardware on both sides of the "pond".

Sadly that is the reason they acquired shares in Reaction Engines for military purposes only (for the moment ),
it does mean. I think Skylon is anchored up a backwater for the present time, but I do have high hopes it will come good sometime in the next 10/20 years.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alpha_Centauri on 07/04/2016 01:41 pm
For Skylon to ever have any chance of literally taking off the cost to the investor needs to be reduced substantially. That means the engine development would need to be largely complete and there would need to be an industrial chain in place for the construction of hypersonic vehicles.

If it takes USAF funds to achieve that then I'm not going to complain.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 07/04/2016 01:44 pm
BAE Systems have released a video of a single-engined Mach 5 vehicle which is clearly SABRE-derived:

I remember  Alan Bond talking about some sort of military consulting or other work, quite some time ago) and when asked more, he said something like:  "well  you know - it's always about small pointy things zooming around"  or words to that effect.

I suspect this is only new news to the public

I watched that film recently about the US ambassador/representative to Libya. One can imagine how useful it would have been for them to receive reconnaissance/other support very quickly.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/04/2016 03:48 pm
This article gives some context to the above video from BAe.

http://www.janes.com/article/61966/bae-systems-reveals-advanced-r-d-concepts
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 07/04/2016 05:24 pm
If BAC do intend to use SABRE as shown in the video as an atmospheric vehicle , I was under the impression LAPCAT was the design best  suited to this form of flight, is SABRE capable of prolonged flight in the
 atmosphere ?.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: dror on 07/04/2016 05:42 pm
Thanks for posting. I wonder who the intended audience is... As you say, it's clearly influenced by Skylon/SABRE, but I wonder if that influence is simply artistic/aesthetic.

(And I certainly hope we don't have to wait for those holographic projection screens to be developed before seeing some flying REL hardware!)

Seems like a possible XS1 contender.
 ???
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Archibald on 07/04/2016 05:43 pm
That video, well... it screams "THUNDERBIRDS ARE GO !!!"

Also, (at 0:18 in the video) it looks strikingly like those old ramjet-powered Leduc birds of the 50's, particularly the 021
(http://jn.passieux.free.fr/images/Leduc021.jpg)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 07/04/2016 07:13 pm
BAE Systems have released a video of a single-engined Mach 5 vehicle which is clearly SABRE-derived:

I remember  Alan Bond talking about some sort of military consulting or other work, quite some time ago) and when asked more, he said something like:  "well  you know - it's always about small pointy things zooming around"  or words to that effect.

I suspect this is only new news to the public

I watched that film recently about the US ambassador/representative to Libya. One can imagine how useful it would have been for them to receive reconnaissance/other support very quickly.
They refuse flat out discussed the work Reaction Engines have undertaken for the MOD, only saying they done work for the MOD.
I'm presuming this will use Reaction Engine work in Lapcat than it work into Sabre and Skylon.  Although BAE might want to get a working engine that runs on the ground first before pursuing any real projects that involves using Reaction Engine technologies.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Asteroza on 07/05/2016 12:59 am
I wonder if that might be a backdoor war to fund the nacelle test vehicle? In the same vein as other marginally militarily useful vehicles like the X-37...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 07/05/2016 04:36 am
I wonder if that might be a backdoor war to fund the nacelle test vehicle? In the same vein as other marginally militarily useful vehicles like the X-37...
I hope that was a Freudian slip! We don't need any more wars to achieve political aims.

That said, the original proposed NTV had identical twin-engine configuration as Skylon, just with a shorter Sears-Haack body. I'm not sure how useful the BAE configuration would be for testing either the nacelle nor SABRE, given the stated purpose of Mach 5 "rapid response" cruise, not orbital launch.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: momerathe on 07/05/2016 07:28 am
Good point. Can anyone think what the implications of having the intake and the engine much more widely separated would be? (It's probably just brochure-ware, but still)

Would you put the pre-cooler at the front or the back? and would you just be getting back to the centre-of-mass problems that Hotol had?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: STS-200 on 07/05/2016 12:16 pm
If BAC do intend to use SABRE as shown in the video as an atmospheric vehicle , I was under the impression LAPCAT was the design best  suited to this form of flight, is SABRE capable of prolonged flight in the
 atmosphere ?.

REL are developing SABRE as a booster engine not a sustainer, however they don't say this is SABRE (the article only says "along the lines of"). At Mach 5-6, I can't see why they would want any of the rocket engine aspects of SABRE.

Nitpick - they haven't been called BAC since 1977.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Asteroza on 07/05/2016 11:16 pm
I wonder if that might be a backdoor war to fund the nacelle test vehicle? In the same vein as other marginally militarily useful vehicles like the X-37...
I hope that was a Freudian slip! We don't need any more wars to achieve political aims.

That said, the original proposed NTV had identical twin-engine configuration as Skylon, just with a shorter Sears-Haack body. I'm not sure how useful the BAE configuration would be for testing either the nacelle nor SABRE, given the stated purpose of Mach 5 "rapid response" cruise, not orbital launch.

Well, spellcheck won't prevent putting my foot in my mouth...

Rapid response as a term these days generally falls into non-ballistic depressed trajectory profiles to "show" you aren't delivering a nuke. Using SABRE as a booster engine for a boost-glide hypersonic delivery vehicle sort of fits. If it's like Hypersoar, you could potentially skip glide to target, drop payload, and reboost home, but that makes the fuselage design much harder. Though skip gliding and the ostensible boost-glide are a bit different, as skip glide had a secondary objective of getting out of the atmosphere to reduce heating.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Hankelow8 on 07/07/2016 10:50 pm
If BAC do intend to use SABRE as shown in the video as an atmospheric vehicle , I was under the impression LAPCAT was the design best  suited to this form of flight, is SABRE capable of prolonged flight in the
 atmosphere ?.

REL are developing SABRE as a booster engine not a sustainer, however they don't say this is SABRE (the article only says "along the lines of"). At Mach 5-6, I can't see why they would want any of the rocket engine aspects of SABRE.

Nitpick - they haven't been called BAC since 1977.

Dear Nitpick!,

Thanks for bringing me back to present day (freudian slip).
It does look very much like "British Aerospace" are concentrating on the military aspects of SABRE/LAPCAT designs, great shame if Skylon is frozen out, but I still think the concept in 20 years will be what drives down cost even further with even greater reliability from the skylon type design.

How about views on what satellite launchers will be like in 30 years time, open to any thoughts from the forum on this, new thread I would think.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Archibald on 07/08/2016 06:21 am
IMVHO If they concentrate on LAPCAT rather than Skylon it is a very mad move - kinetic friction born out of  hours long cruise at Mach 5 is much more complicated than reaching orbit. And noise will be a problem, as will integration into airports and ATC.
Seriously - go for skylon !
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 07/08/2016 08:46 am
IMVHO If they concentrate on LAPCAT rather than Skylon it is a very mad move - kinetic friction born out of a hours long cruise at Mach 5 is much more complicated than reaching orbit. And noise will be a problem, as will integration into airports and ATC.
Seriously - go for skylon !

I don't think there's any suggestion of that.  They seem to have done some design work for a vehicle that is (I assume) a lot smaller than LAPCAT since there is no need to carry passengers. Possibly the engine might bear some slight comparison with the one proposed for lapcat.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/08/2016 01:14 pm
Thanks for bringing me back to present day (freudian slip).
It does look very much like "British Aerospace" are concentrating on the military aspects of SABRE/LAPCAT designs, great shame if Skylon is frozen out, but I still think the concept in 20 years will be what drives down cost even further with even greater reliability from the skylon type design.
They aren't called that either.

It's BAe Systems. And their nearest counterpart is neither Boeing or even ULA, it's LM.

The company that brought you the X33.

This is not a proud pedigree for lowering costs.   :(

I don't think there's any suggestion of that.  They seem to have done some design work for a vehicle that is (I assume) a lot smaller than LAPCAT since there is no need to carry passengers. Possibly the engine might bear some slight comparison with the one proposed for lapcat.

Scimitar was the engine, LAPCAT was the EU programme that funded and the outline REL design to carry the engine was A2.

Scimitar is a very different design to SABRE as it's a very different mission.

BTW interesting point about LAPCAT was REL was one of 2 designs remaining. The other was German. They said they could do a M8 SCramjet but it could not quite meet the mission range requirements. REL can't match that (theoretical) top speed but their design met the range requirements comfortable, although only 2.2x faster than Concorde.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/08/2016 01:23 pm
ESA will be at Farmborough 11-17th July in the Hall 3 "Space Zone." Tuesday the 12th is "Space Day.

http://www.esa.int/About_Us/Exhibitions/FIA_2016/ESA_at_FIA_2016_-_Programme_of_key_events

Not especially 1130-1200

"Signature of the contract for the continued development of the SABRE - Synergetic Air-Breathing Rocket Engine - Phase 3B programme, "

If I'm reading this right then 3a is complete.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/08/2016 01:32 pm
IMVHO If they concentrate on LAPCAT rather than Skylon it is a very mad move - kinetic friction born out of a hours long cruise at Mach 5 is much more complicated than reaching orbit. And noise will be a problem, as will integration into airports and ATC.
Seriously - go for skylon !
True. The nicest short description of hypersonic cruise is "continuous re-entry."

In theory that will be the airframe mfg's problem.  :(

I remember  Alan Bond talking about some sort of military consulting or other work, quite some time ago) and when asked more, he said something like:  "well  you know - it's always about small pointy things zooming around"  or words to that effect.
Quote
Bond has mentioned that he has worked on problems of "National Defense." There is one area that countries have studied continuously in high speed flight and that's in respect to warhead reentry. In the UK that would have been the "Chevaline" project.
I watched that film recently about the US ambassador/representative to Libya. One can imagine how useful it would have been for them to receive reconnaissance/other support very quickly.
Don't get too excited. The USAF scrapped the SR71 because they didn't want to maintain the JP7 supply chain of storage tanks and tankers to carry it and that's room temperature storable.

LH2 is chemically much simpler to make but very difficult to store.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 07/08/2016 01:36 pm
ESA will be at Farmborough 11-17th July in the Hall 3 "Space Zone." Tuesday the 12th is "Space Day.

http://www.esa.int/About_Us/Exhibitions/FIA_2016/ESA_at_FIA_2016_-_Programme_of_key_events

Not especially 1130-1200

"Signature of the contract for the continued development of the SABRE - Synergetic Air-Breathing Rocket Engine - Phase 3B programme, "

If I'm reading this right then 3a is complete.


Phase 3A is the final design of the ground test engine?

Phase 3B would be the construction of that engine?
Phase 3C would be ground testing that engine and resolving any technological problems they encounter?

Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/08/2016 03:28 pm
IMVHO If they concentrate on LAPCAT rather than Skylon it is a very mad move - kinetic friction born out of a hours long cruise at Mach 5 is much more complicated than reaching orbit. And noise will be a problem, as will integration into airports and ATC.
Seriously - go for skylon !

At the end of the day you build what the customer wants and what they are paying you for. I doubt the military are that concerned by noise as such vehicles would operate out of airbases in the middle of nowhere.

I am increasing convinced BAE are far more interested in building something for the USAF than doing anything with Skylon any time soon. In fact it's a pretty good guess that's why the invested in REL in the first place.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 07/08/2016 04:52 pm
I think we should wait until we see their announcements at Farmborough before coming to any conclusions. The fact they continue to mention previous programs that were aimed at developing Skylon, suggests they plan on at least building Sabre test engine, which is probably the biggest step needed to produce Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/08/2016 07:07 pm
ESA will be at Farmborough 11-17th July in the Hall 3 "Space Zone." Tuesday the 12th is "Space Day.

http://www.esa.int/About_Us/Exhibitions/FIA_2016/ESA_at_FIA_2016_-_Programme_of_key_events

Not especially 1130-1200

"Signature of the contract for the continued development of the SABRE - Synergetic Air-Breathing Rocket Engine - Phase 3B programme, "

If I'm reading this right then 3a is complete.


Phase 3A is the final design of the ground test engine?

Phase 3B would be the construction of that engine?
Phase 3C would be ground testing that engine and resolving any technological problems they encounter?
In one of the REL reports key items listed in 3a (from memory can't find the report).

Final decision on SABRE 3 or 4 cycle
Improve inlet modelling
Thrust chamber manufacture development
Heat exchanger mfg improvement
Design ground demonstration
System design requirements review.

"3b" would appear to be "make it happen."
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Misha Vargas on 07/08/2016 07:27 pm
They aren't called that either.

It's BAe Systems.

You're still one merger behind the times in capitalization. It's BAE Systems.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: momerathe on 07/08/2016 09:59 pm
It's BAe Systems. And their nearest counterpart is neither Boeing or even ULA, it's LM.

Even that's not a terribly good comparison. BAE haven't made a whole new aircraft in 20 years or more (excluding drones). I don't doubt that BAE can develop the engine, but I do doubt their ability to build a Skylon.
Title: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/08/2016 10:03 pm
It's BAe Systems. And their nearest counterpart is neither Boeing or even ULA, it's LM.

Even that's not a terribly good comparison. BAE haven't made a whole new aircraft in 20 years or more (excluding drones). I don't doubt that BAE can develop the engine, but I do doubt their ability to build a Skylon.

I don't see why you're excluding drones being as Skylon is also a drone.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 07/09/2016 12:39 am
It's BAe Systems. And their nearest counterpart is neither Boeing or even ULA, it's LM.

Even that's not a terribly good comparison. BAE haven't made a whole new aircraft in 20 years or more (excluding drones). I don't doubt that BAE can develop the engine, but I do doubt their ability to build a Skylon.
Skylon is a drone and so is the craft they show in the video.

The only area BAE might not have all of the in house know how or knowledge that can be brought in from other companies, is how to construct a heat shield that is capable of withstanding multiple reentries and other technologies in that area. Reaction Engines have done some work on this but I'm pretty certain if Skylon went ahead a tonne more work would have to be done on those areas before construction of the vehicle could begin.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Ravenger on 07/09/2016 10:58 pm
Looks like REL are moving towards a new phase in Sabre development.

They're recruiting a Production Manager 'To plan, direct and coordinate all manufacturing operations and activities in line with company strategy and business plan.'

http://www.reactionengines.co.uk/careers_031productionmanager.html

Key Responsibilities and Accountabilities:

Establish the overall manufacturing vision and implement world-class manufacturing capabilities
Ensure manufacturing capability and capacity is available to support the SABRE programme, including fast make
Maximise the financial, human and capital assets while meeting the production schedule and objectives
Drive and reinforce lean manufacturing principles at all levels in the organisation
Lead efforts to continuously control costs, improve efficiency and productivity
Maximise opportunities for return on investment through commercial customers
Develop and lead a high performing team, well integrated with the wider organisation
Promote core company behaviours and accountability, leading by example
Planning and organising production schedules
Estimating, forecasting and agreeing budgets and timescales with customers (internal & external)
Procedure and process management
Accountability of HS&E for manufacturing facilities/sites
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/10/2016 11:06 am
The only area BAE might not have all of the in house know how or knowledge that can be brought in from other companies, is how to construct a heat shield that is capable of withstanding multiple reentries and other technologies in that area. Reaction Engines have done some work on this but I'm pretty certain if Skylon went ahead a tonne more work would have to be done on those areas before construction of the vehicle could begin.
It's not called a heat shield, it's called a skin and it's the other area that REL have (quietly) been working on.

In truth no one has experience of building using these materials. However at least 2 aircraft have flown with corrugated panel structures, including the SR71. The structural architecture for Skylon is very conservative, being panels riveted to a framework. This is well understood and frequently used. 

More to the point the issues around these designs are well understood.  The properties those parts need to have to build a safe vehicle is also known.

However let's keep in mind that REL's core goal is the mfg of the engine for a vehicle, not the vehicle itself.

REL's key problems are not technical, but financial. Specifically how to turn interest in the SABRESkylon into actual commitments that can be taken to banks for funding when the organization that builds it has not been formed yet.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: topsphere on 07/11/2016 01:00 pm
A tweet from REL states "We've strengthened our management team and opened a US Office".


https://twitter.com/ReactionEngines/status/752487279814406144

link to their news update

http://www.reactionengines.co.uk/news_11jul2016.html
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Chris Bergin on 07/11/2016 01:10 pm
Beat me to it, Mr. Fast Fingers ;D

That is probably the most interesting thing about them for a long time. A step forward.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 07/11/2016 04:02 pm
A tweet from REL states "We've strengthened our management team and opened a US Office".


https://twitter.com/ReactionEngines/status/752487279814406144

link to their news update

http://www.reactionengines.co.uk/news_11jul2016.html
The biggest news here is Reaction Engines actually have a Twitter Account! I thought this whole PR mullarkey was beyond them.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: docmordrid on 07/11/2016 06:42 pm
And their nearest counterpart is neither Boeing or even ULA, it's LM.
... Dr. Dissel joins Reaction Engines Inc. from Lockheed Martin Space Systems

Interesting since Lockmart is one of the suitors rumored to be interested in acquiring BAE.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/11/2016 07:08 pm
And their nearest counterpart is neither Boeing or even ULA, it's LM.
... Dr. Dissel joins Reaction Engines Inc. from Lockheed Martin Space Systems

Interesting since Lockmart is one of the suitors rumored to be interested in acquiring BAE.

I hope not. Reckon Brexit will put off any such suitors anyway.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 07/11/2016 10:02 pm
According to the Financial times Reaction Engine now has funding for a sabre demonstration engine,

https://next.ft.com/content/f879fe82-4782-11e6-8d68-72e9211e86ab (https://next.ft.com/content/f879fe82-4782-11e6-8d68-72e9211e86ab)

I presume that BAE must be offering substantial in kind and probably additional cash support on top of the 60 million coming from ESA and UKSA for the construction of this demonstration than the currently stated 20 million.

As the original budget for the ground engine demonstrator was 200 to 300 million.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/11/2016 10:05 pm
According to the Financial times it has funding,

https://next.ft.com/content/f879fe82-4782-11e6-8d68-72e9211e86ab (https://next.ft.com/content/f879fe82-4782-11e6-8d68-72e9211e86ab)
Nothing but pay wall on that link.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 07/11/2016 10:09 pm
According to the Financial times it has funding,

https://next.ft.com/content/f879fe82-4782-11e6-8d68-72e9211e86ab (https://next.ft.com/content/f879fe82-4782-11e6-8d68-72e9211e86ab)
Nothing but pay wall on that link.

 :(  it working for me, not a subscriber, usually you get 5 article free month from the site. Not sure you are allowed to copy the whole article, but here it is anyway, This what the article state,
Quote
Reaction Engines  Follow
Reaction Engines secures funding for space engine
UK start-up to produce demonstrator of its Sabre technology that could transform travel beyond earth


3 HOURS AGO by: Peggy Hollinger in Farnborough

Britain has given the go-ahead to crucial development funding for a revolutionary UK designed engine that could send aircraft into outer space and back at five times the speed of sound.

Reaction Engines, founded by British engineer Alan Bond, has signed a €10m development contract with the European Space Agency, which unlocks £50m from the UK Space Agency.

The funding will allow Reaction, a UK start-up now 20 per cent owned by British defence company BAE Systems, to build a ground-based demonstrator of its Sabre engine.


This is supposed to power Skylon, a space aircraft also designed by Reaction.

Originally developed by former Rolls-Royce engineer Mr Bond and two business partners more than 30 years ago, the Sabre technology has passed technical assessments by the US air force and the European Space Agency.

The Sabre design for a reusable hybrid rocket cum jet engine promises to transform the economics of space.

Reaction said the agreements with the European Space Agency and the UK Space Agency, as well as the industrial partnership with BAE Systems, would enable it to “deliver the world’s first Sabre ground demonstrator engine by the end of the decade”.

Mark Thomas, Reaction’s chief executive, said: “We’ve had valuable support from [the European Space Agency] and [the UK Space Agency] to date, and today’s agreement is a further vote of confidence not only in the revolutionary potential of this technology, but our ability to deliver on it.

“We are now entering an exciting phase where we can accelerate the pace of development to get [Sabre] up and running.”
.




Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/11/2016 11:51 pm
I'd be very careful of wholesale posting of a copyright item.  :(

However for once the REL PR "department" has actually made an announcement.

http://www.reactionengines.co.uk/news_11jul2016.html

the establishment of a US division appears to be SOP in the defense business because, bluntly the DoD simply don't feel comfortable with dealing with foreign companies unless they have some sort of firewalled system so US secrets can't be transferred abroad.

Of course in this case the actual dangers is transfer of UK held (commercial) secrets to the US.  :(

There are a couple of interesting things about Dr Dissel.

Firstly LM (unlike BAE) have not invested in REL. Executives from BAE can expect to have retained some of their pension and other benefits from BAE. In principal he would have none. That means he's either looking at REL matching them, which I think is a pretty serious amount of cash, or he's expecting some sort of stock option.

But that only makes sense if REL is going public. ??

His previous title at LM "System Architect for Responsive Space" is also interesting. "Responsive Space" has been the US military phrase for fast call up and deployment of military space assets and what that needs. This is not the "SR72." It's LEO, short lifetime payloads to expand capacity of "something" in a particular theater of operations. It meant looking at things like standard satellite payloads, either as 1 sensor per satellite or some kind of "tinker toy" plug-n-play assembly with streamlining things like coupled loads analysis.

Which suggest Dr Dissel may have a vehicle design that could be flexed to carry SABRE, or something similar.

[EDIT This article gives a sense of the sort of things the US military means by "responsive space."
http://spacenews.com/ors-director-were-not-here-to-build-neat-toys/

obviously if one moves away from  "artillery range" style launch operations things can run much more smoothly, provided a suitable vehicle exists. ]
]
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: oddbodd on 07/12/2016 01:50 am
Interesting since Lockmart is one of the suitors rumored to be interested in acquiring BAE.

I hope not. Reckon Brexit will put off any such suitors anyway.

This is the ideal time for predatory antics. The GBP is some 13% down against the USD. It depends on the overall LM strategy, but the simplistic cost of acquisition/merger just dropped substantially.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: oddbodd on 07/12/2016 01:56 am
I'd be very careful of wholesale posting of a copyright item.  :(

Quote
Copyright The Financial Times Limited 2016. All rights reserved. You may share using our article tools. Please don't cut articles from FT.com and redistribute by email or post to the web.

He even copied the bit that told not to copy the article. So at least he was thorough  :o
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 07/12/2016 07:16 am
I'd be very careful of wholesale posting of a copyright item.  :(

However for once the REL PR "department" has actually made an announcement.

http://www.reactionengines.co.uk/news_11jul2016.html

That doesn't mention the bit about the funds from UK Space Agency finally being released to Reaction engines and additional funding from ESA and confirmation that construction of a Sabre engine ground demonstrator is to begin. Which is something we been speculating on since we found out an announcement of  BAE have release that video and we also been speculating about what exactly Phase 3B programme.

It was never financial problems that prevents someone like Lockheed Martin buying up BAE, it political opposition that will be enormous for any deal that involves the UK selling it one and only remaining large defence firm. The only way would be for the whole firm to base in the UK with UK government maintain a golden share, that I presume would be completely unacceptable for the US government and the Pentagon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/12/2016 09:02 am
That doesn't mention the bit about the funds from UK Space Agency finally being released to Reaction engines and additional funding from ESA and confirmation that construction of a Sabre engine ground demonstrator is to begin. Which is something we been speculating on since we found out an announcement of  BAE have release that video and we also been speculating about what exactly Phase 3B programme.
An interesting question is wheather this is finally the bulk of the £60m George Osborne promised REL in 2013 or if it's in addition to that funding. If it's the latter that's a substantial boost to their development funding.
Quote
It was never financial problems that prevents someone like Lockheed Martin buying up BAE, it political opposition that will be enormous for any deal that involves the UK selling it one and only remaining large defence firm.
It's not the only large defense company in the UK but I think it's the last remaining prime, being able to handle the epic levels of MoD paperwork and years of selection needed to win a weapon system contract.

Note it is the last remaining prime because of the MoD desire to create a "national champion." This same line of thinking is why there are only 3 major defense conglomerates left in the US.  The theory was all about "economies of scale" and "synergy" between widely divergent divisions. No one mentioned the dis economies of scale, the astonishing increase in bureaucracy or the fact that IRL the ballistic missile submarine division has not helped in the construction of new aircraft, or vice versa.  :(
Quote
The only way would be for the whole firm to base in the UK with UK government maintain a golden share, that I presume would be completely unacceptable for the US government and the Pentagon.
The UK Govt already has a "Golden" share. BAE gets on demand access to the Prime Ministers office, something I doubt even the CEO of LM can match. Something I don't think any CEO should have as a right.

IRL AFIK the bulk of BAE's income does not come from the UK, I'm not convinced it's designed-exactly-to-MoD-requirments products are better than other countries across the board and in the case of the Nimrod MR4 project, werevastly expensive and a total failure to deliver a capability, as welling as killing a whole (large) aircrew in the process.  :(

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 07/12/2016 09:29 am
Finally!

FT reports Sabre getting the money it was promised (10 M eur + 50M pounds)

Also, the FT reports the creation of a REL subsidiary in US to deal with US gvt contracts. it will be led by a former Lockheed executive.

https://next.ft.com/content/f879fe82-4782-11e6-8d68-72e9211e86ab#axzz4E8vmccUO
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Chris Bergin on 07/12/2016 01:15 pm
ESA on SABRE:

http://tinyurl.com/zuerv9z (was a massive ESA URL, so shortened it).
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/12/2016 02:45 pm
Just hope Brexit doesn't blow this whole project off course.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 07/12/2016 03:16 pm
Just hope Brexit doesn't blow this whole project off course.
Or this thread, yet again.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alpha_Centauri on 07/12/2016 05:00 pm
At this rate perhaps we should Brexit more often... ;)

Anyway I don't know if this has been discussed previously but the Beeb has more about a tie-up with small-sat launcher project Orbital Access Limited to get flight data with scaled down versions of SABRE.

http://www.bbc.co.uk/news/science-environment-36773074

Quote
But because the engine technology is considered scalable, Reaction Engines announced at Farnborough that it is also joining a consortium to look at the feasibility of putting reduced-sized power units on smaller vehicles that could run out of Prestwick airport.

Orbital Access Limited is the company behind the effort to turn the Scottish aviation centre into a spaceport. It is already working with BAE Systems - a major shareholder in REL - to turn a DC10 into a flying platform from which to launch rocket-carrying satellites.

It is keen to see if it is possible to piggyback additional launch services on some of the future test flight models that Reaction Engines will build to further develop Sabre.

"What this study aims to do is to look at those vehicle concepts and evaluate which sorts of configurations can yield commercial payload capabilities," explains Orbital's CEO Stuart McIntyre.

"If you take a Sabre test engine, put wings on it and go fly it, all you'll get is some engineering answers. But if we do these flight tests in a certain way, where you plug a top stage to these vehicles, it may then be possible for REL to get their air test data and for us to launch payloads."

Edit; the article above appears to have been edited, it previously mentioned that "The Sabre/Prestwick feasibility study is receiving a £250,000 grant from the UKSA."

http://webcache.googleusercontent.com/search?q=cache:http://www.bbc.co.uk/news/science-environment-36773074
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 07/12/2016 07:06 pm
A minor point maybe, but it appears "SABRE" has become "Sabre" in REL nomenclature. Apart from the article above, Richard Varvill has been using "Sabre" recently.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: LM13 on 07/12/2016 07:14 pm
A minor point maybe, but it appears "SABRE" has become "Sabre" in REL nomenclature. Apart from the article above, Richard Varvill has been using "Sabre" recently.

That might just be the BBC--to my recollection, they have also customarily called NASA "Nasa."  A British acquaintance of mine once told me that it's not customary on that side of the Atlantic to capitalize all letters in an acronym.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alpha_Centauri on 07/12/2016 07:18 pm
^^
Yes that's because of changes to media style guides that are, in my opinion, butchering the language.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/12/2016 07:33 pm
At this rate perhaps we should Brexit more often... ;)

Anyway I don't know if this has been discussed previously but the Beeb has more about a tie-up with small-sat launcher project Orbital Access Limited to get flight data with scaled down versions of SABRE.

http://www.bbc.co.uk/news/science-environment-36773074
Edit; the article above appears to have been edited, it previously mentioned that "The Sabre/Prestwick feasibility study is receiving a £250,000 grant from the UKSA."

http://webcache.googleusercontent.com/search?q=cache:http://www.bbc.co.uk/news/science-environment-36773074
I've never heard of Orbital Access Limited before.

And I'm very surprised that they think SABRE is scalable down to that sort of size.

IIRC the big issue remains the LH2 pump due to the still high chamber pressure needed, although SABRE 4 seems to offer a possible much lower pressure chamber for the pure rocket mode.

This opens possibilities.

Keep in mind that due to its nature REL will probably need to consider the whole nacelle carrying it as well. That strongly suggests work in fibre reinforced SiC or some kind of RCC, of which there are a number of mfg in Europe, notably in Germany.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: SICA Design on 07/12/2016 07:45 pm
A minor point maybe, but it appears "SABRE" has become "Sabre" in REL nomenclature. Apart from the article above, Richard Varvill has been using "Sabre" recently.

That might just be the BBC--to my recollection, they have also customarily called NASA "Nasa."  A British acquaintance of mine once told me that it's not customary on that side of the Atlantic to capitalize all letters in an acronym.

Richard Varvill is the Chief Engineer at REL - he is using "Sabre" in email. He has also referred recently to the possibility of TSTO, which may have been an informal reference to the Orbital Access work.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alpha_Centauri on 07/12/2016 07:57 pm
At this rate perhaps we should Brexit more often... ;)

Anyway I don't know if this has been discussed previously but the Beeb has more about a tie-up with small-sat launcher project Orbital Access Limited to get flight data with scaled down versions of SABRE.

http://www.bbc.co.uk/news/science-environment-36773074
Edit; the article above appears to have been edited, it previously mentioned that "The Sabre/Prestwick feasibility study is receiving a £250,000 grant from the UKSA."

http://webcache.googleusercontent.com/search?q=cache:http://www.bbc.co.uk/news/science-environment-36773074
I've never heard of Orbital Access Limited before.

And I'm very surprised that they think SABRE is scalable down to that sort of size.

IIRC the big issue remains the LH2 pump due to the still high chamber pressure needed, although SABRE 4 seems to offer a possible much lower pressure chamber for the pure rocket mode.

This opens possibilities.

Keep in mind that due to its nature REL will probably need to consider the whole nacelle carrying it as well. That strongly suggests work in fibre reinforced SiC or some kind of RCC, of which there are a number of mfg in Europe, notably in Germany.

Me neither, it's a new outfit that is intending to be the operator running out of a future Prestwick Spaceport, apparently they are sourcing a DC-10 for an air-launch system.

http://www.orbital-access.com/our-projects.html

Remember the work done by Strathclyde on alternative Skylon designs?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 07/12/2016 09:03 pm
At this rate perhaps we should Brexit more often... ;)

Anyway I don't know if this has been discussed previously but the Beeb has more about a tie-up with small-sat launcher project Orbital Access Limited to get flight data with scaled down versions of SABRE.

http://www.bbc.co.uk/news/science-environment-36773074

Quote
But because the engine technology is considered scalable, Reaction Engines announced at Farnborough that it is also joining a consortium to look at the feasibility of putting reduced-sized power units on smaller vehicles that could run out of Prestwick airport.

Orbital Access Limited is the company behind the effort to turn the Scottish aviation centre into a spaceport. It is already working with BAE Systems - a major shareholder in REL - to turn a DC10 into a flying platform from which to launch rocket-carrying satellites.

It is keen to see if it is possible to piggyback additional launch services on some of the future test flight models that Reaction Engines will build to further develop Sabre.

"What this study aims to do is to look at those vehicle concepts and evaluate which sorts of configurations can yield commercial payload capabilities," explains Orbital's CEO Stuart McIntyre.

"If you take a Sabre test engine, put wings on it and go fly it, all you'll get is some engineering answers. But if we do these flight tests in a certain way, where you plug a top stage to these vehicles, it may then be possible for REL to get their air test data and for us to launch payloads."

Edit; the article above appears to have been edited, it previously mentioned that "The Sabre/Prestwick feasibility study is receiving a £250,000 grant from the UKSA."

http://webcache.googleusercontent.com/search?q=cache:http://www.bbc.co.uk/news/science-environment-36773074
Wonder if that means Prestwick has now become the favourite to host the UK spaceport.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 07/12/2016 09:12 pm
At this rate perhaps we should Brexit more often... ;)

Anyway I don't know if this has been discussed previously but the Beeb has more about a tie-up with small-sat launcher project Orbital Access Limited to get flight data with scaled down versions of SABRE.

http://www.bbc.co.uk/news/science-environment-36773074
Edit; the article above appears to have been edited, it previously mentioned that "The Sabre/Prestwick feasibility study is receiving a £250,000 grant from the UKSA."

http://webcache.googleusercontent.com/search?q=cache:http://www.bbc.co.uk/news/science-environment-36773074
I've never heard of Orbital Access Limited before.

And I'm very surprised that they think SABRE is scalable down to that sort of size.

IIRC the big issue remains the LH2 pump due to the still high chamber pressure needed, although SABRE 4 seems to offer a possible much lower pressure chamber for the pure rocket mode.

This opens possibilities.

Keep in mind that due to its nature REL will probably need to consider the whole nacelle carrying it as well. That strongly suggests work in fibre reinforced SiC or some kind of RCC, of which there are a number of mfg in Europe, notably in Germany.

Me neither, it's a new outfit that is intending to be the operator running out of a future Prestwick Spaceport, apparently they are sourcing a DC-10 for an air-launch system.

http://www.orbital-access.com/our-projects.html

Remember the work done by Strathclyde on alternative Skylon designs?
Quote
THE FSPLUK PROJECT
Conscious that future systems will need to employ the new technologies that are in development the FSPLUK project is a collaboration led by Orbital Access Limited that combines Reaction Engines Limited's SABRE technology with BAE Systems aero-design capability and the leading hypersonic research and trajectory design and optimisation capabilities of Glasgow and Strathclyde Universities to define a road map of new vehicle developments to provide next generation small payload launch vehicles and the air test vehicles required to finesse the development of the SABRE engine. The project also incorporates the UK's leading small satellite manufacturers SSTL and Clyde Space and incorporates their future needs as a primary design imperative for the roadmap. As such the FSPLUK project defines Orbital Access's product development pipeline and integrates the UK industrial base required to realise that product roadmap. The specific outputs targeted by the project is an initial horizontal small payload launch system in service by 2020 with a fully reusable system in service by 2030. The technical and operational learning from these system developments will lay the foundation for the delivery of Skylon in the long term.


To me they sound like someone that has the intention of being the company that builds Skylon and the prototype vehicles needed to test the engines and technologies needed to support Skylon. In fact it reads very much like they intend to be the type of consortium Reaction Engines always wanted to build Skylon, why they presumably refocus completely on developing and building the engines

 Unless I'm reading that wrongly. This is another company to keep a close eye on over the next few years. Sadly no mention of who is financially backing them, beyond the 250k UK Space Agency have given them.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alpha_Centauri on 07/12/2016 09:26 pm
It's a small start-up that looks to be largely an operator procuring systems rather than a manufacturer.  I can see them operating a small BAE-developed skylon-derived prototype TSTO small-sat launcher.  They would not be a Skylon manufacturer.

As for the spaceports, recently there was a disappointing change in policy where the government will only license spaceports rather than patronising a particular site.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 07/12/2016 11:10 pm

As for the spaceports, recently there was a disappointing change in policy where the government will only license spaceports rather than patronising a particular site.
That a shame, they kept that announcement pretty quiet.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Asteroza on 07/12/2016 11:20 pm
How much does this feed back into the AFRL work, considering the USAF may be interested in TSTO (see XS-1)? Is BAE effectively going to sell Orbital Access Ltd's TSTO as a manufacturer?

Is REL now resigned to doing an reduced NTV-esqe vehicle with the associated non-transferrable LH2 pump work, in order to get operational experience at altitude?

An interesting byproduct of such a smallsat TSTO is that it would effectively cement the UK as the leader as far as a vertically integrated marketplace, with smallsat parts manufacturers, whole smallsat manufacturers, and launch services as ITAR unrestricted brands would be backing such a marketplace.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: oddbodd on 07/13/2016 04:08 am
ESA on SABRE:

http://tinyurl.com/zuerv9z (was a massive ESA URL, so shortened it).

Maybe it's just me, but that announcement rubs me the wrong way. It's "ESA did this", "ESA did that". Poor ol' REL are lucky to be in the presence of such giants! /s I honestly have no idea of ESA's real level of contribution to the project till now, but it just sorta gives the impression that it's ESA who got it to where it is now, and REL have made some minor contribution. You know, like all the actual engineering!

I shouldn't be so churlish though. At least there's progress  ;D
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/13/2016 06:33 am

Maybe it's just me, but that announcement rubs me the wrong way. It's "ESA did this", "ESA did that". Poor ol' REL are lucky to be in the presence of such giants! /s I honestly have no idea of ESA's real level of contribution to the project till now, but it just sorta gives the impression that it's ESA who got it to where it is now, and REL have made some minor contribution. You know, like all the actual engineering!
First rule of PR.

The organisation that writes the press release emphasises it's work.

Actually by getting ESA involved to act as a monitor they have done something which (AFAIK) no other newspace company (that does not have an independent backer) have succeeded in doing.

Getting the technical arm of a recognized space agency to look in detail at their design and confirm it will do what they say it will do.

This is one of the key problems with getting commercial funding, sometimes known as "My cousin at NASA," because "My cousin says if it was that good NASA would be doing it."

Readers of this site should be well aware there are in fact many reasons why major space agencies will not support anything outside the mainstream with anything more than the most limited funding.
Quote
I shouldn't be so churlish though. At least there's progress  ;D
If you want to be churlish blame the UK govt and the EU for taking 3 years from George Osbornes announcement. At that point it was going to be a loan which had to be repayed. In the meantime BAE have bought up a significant chunk of the company for a fairly low cost.

Had the money come through faster REL might have remained more independent.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/13/2016 07:25 am

Maybe it's just me, but that announcement rubs me the wrong way. It's "ESA did this", "ESA did that". Poor ol' REL are lucky to be in the presence of such giants! /s I honestly have no idea of ESA's real level of contribution to the project till now, but it just sorta gives the impression that it's ESA who got it to where it is now, and REL have made some minor contribution. You know, like all the actual engineering!
First rule of PR.

The organisation that writes the press release emphasises it's work.

Actually by getting ESA involved to act as a monitor they have done something which (AFAIK) no other newspace company (that does not have an independent backer) have succeeded in doing.

Getting the technical arm of a recognized space agency to look in detail at their design and confirm it will do what they say it will do.

This is one of the key problems with getting commercial funding, sometimes known as "My cousin at NASA," because "My cousin says if it was that good NASA would be doing it."

Readers of this site should be well aware there are in fact many reasons why major space agencies will not support anything outside the mainstream with anything more than the most limited funding.
Quote
I shouldn't be so churlish though. At least there's progress  ;D
If you want to be churlish blame the UK govt and the EU for taking 3 years from George Osbornes announcement. At that point it was going to be a loan which had to be repayed. In the meantime BAE have bought up a significant chunk of the company for a fairly low cost.

Had the money come through faster REL might have remained more independent.

Or you might regard their investment as a vote of confidence and providing a strong backer. Independence maybe over-rated in this case.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: topsphere on 07/13/2016 01:37 pm
Just hope Brexit doesn't blow this whole project off course.

It was an internal European Commission review that delayed the £60m government grant to REL by several years. I don't want to take the thread off topic again but if this experience is anything to go by, it will drastically speed up any state funds REL may receive.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Mutley on 07/13/2016 01:48 pm
Was anybody at the Reaction Engines presentation at the Farnborough international Airshow today? 

Have seen some slides on twitter including a new image of a ground test engine.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 07/13/2016 05:18 pm
How much does this feed back into the AFRL work, considering the USAF may be interested in TSTO (see XS-1)? Is BAE effectively going to sell Orbital Access Ltd's TSTO as a manufacturer?

Is REL now resigned to doing an reduced NTV-esqe vehicle with the associated non-transferrable LH2 pump work, in order to get operational experience at altitude?

An interesting byproduct of such a smallsat TSTO is that it would effectively cement the UK as the leader as far as a vertically integrated marketplace, with smallsat parts manufacturers, whole smallsat manufacturers, and launch services as ITAR unrestricted brands would be backing such a marketplace.
I think REL is resign to what it always wanted to be a engine maker. I think BAE will now take over the design of any vehicles that use the engines REL produces, and we won't see any new work from Reaction Engine on Skylon, that will either all come out of BAE or another company or consortium at a later date.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/13/2016 05:54 pm
How much does this feed back into the AFRL work, considering the USAF may be interested in TSTO (see XS-1)? Is BAE effectively going to sell Orbital Access Ltd's TSTO as a manufacturer?

Is REL now resigned to doing an reduced NTV-esqe vehicle with the associated non-transferrable LH2 pump work, in order to get operational experience at altitude?

An interesting byproduct of such a smallsat TSTO is that it would effectively cement the UK as the leader as far as a vertically integrated marketplace, with smallsat parts manufacturers, whole smallsat manufacturers, and launch services as ITAR unrestricted brands would be backing such a marketplace.
I think REL is resign to what it always wanted to be a engine maker. I think BAE will now take over the design of any vehicles that use the engines REL produces, and we won't see any new work from Reaction Engine on Skylon, that will either all come out of BAE or another company or consortium at a later date.

Surely that plays to their strengths.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 07/20/2016 08:57 am
So, on Friday Richard Varvill will deliver a Skylon Update to the BIS conference. What are they likely to say, and what would you want them to say?

Want them to say?

"we secured (X) customers who have put refundable deposits on our books so we can finally move towards airframe maker selection & speed up ground testing. We will deliver on schedule."

jokes aside, I would like them to develop over recent remarks that the ground test article is going to be "much cheaper originally expected". Is it due to cutting on costs, or is it due to early conservative estimates?
if the latter, is there any hope that (1) the already-confirmed cost reductions for the ground test articles are applicable to the real engines, and that (2) the overall cost estimates are equally conservative?

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 07/20/2016 10:09 am
So, on Friday Richard Varvill will deliver a Skylon Update to the BIS conference. What are they likely to say, and what would you want them to say?

I expect a restatement of what we know already with a big fuzzy area around anything that might involve the AFRL or BAE systems.

What they should say:

What about the plumes issue?
Did they pick SABRE4 yet ?
How did they make their demo engine cheaper?
What's with this Orbital Access deal? How can it possibly help them? Surely it would have to take full scale SABRE engines since they can't be made smaller? Or would it just test nacelles or other aspects of the technology?
How are they getting along with designing the various heat exchangers (other than the precooler)?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Soundbite on 07/20/2016 12:35 pm
Quote
What's with this Orbital Access deal? How can it possibly help them? Surely it would have to take full scale SABRE engines since they can't be made smaller?

If you look at reaction engines update it quite clearly states the engine is highly scalable
Quote
...enable the development of a ground based demonstrator of SABRETM, a new class of aerospace engine which is highly scalable with multiple potential applications in hypersonic travel and space access.
see http://reactionengines.co.uk/news_updates.html (http://reactionengines.co.uk/news_updates.html)

When reaction engines built the pre-cooler demonstrator in 2012, Alan Bond stated that they were originally going to use 3 pre-cooler modules in front of the viper engine, however they didn't have enough funds to do that.  They only had enough funds to use 1 pre-cooler module and that is what they went with.

IMHO I think that Alan Bond and Reactions Engines had originally planned for a 'Rolls Royce' Development programme, but reality is now setting in and they have to go for the cheapest development programme they can get away with that proves what they need to prove.

I have always thought that a £12 Bn development programme was just too expensive.  TBH I think the cost of the design and development should be halved to £6 Bn.  There are a whole new bunch of technologies that should help them reduce the cost since they first calculated the programme cost....  much more detailed and accurate advanced design & simulation software... 3D printing etc....   It is obvious to me that, that is why they have employed Mark Wood to focus on reducing costs
Quote
...Chief Operating Officer & Engineering Director, with responsibility for operational leadership, improving the efficiency and effectiveness of the business through integration, collaboration and operational best practices.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 07/20/2016 12:54 pm
So, on Friday Richard Varvill will deliver a Skylon Update to the BIS conference. What are they likely to say, and what would you want them to say?

Want them to say?

"we secured (X) customers who have put refundable deposits on our books so we can finally move towards airframe maker selection & speed up ground testing. We will deliver on schedule."

jokes aside, I would like them to develop over recent remarks that the ground test article is going to be "much cheaper originally expected". Is it due to cutting on costs, or is it due to early conservative estimates?
if the latter, is there any hope that (1) the already-confirmed cost reductions for the ground test articles are applicable to the real engines, and that (2) the overall cost estimates are equally conservative?
Could it also be because BAE will be providing a lot of the components without profit margins and sale tax. VAT is 20% cost reduction alone.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 07/20/2016 01:39 pm
Quote
What's with this Orbital Access deal? How can it possibly help them? Surely it would have to take full scale SABRE engines since they can't be made smaller?

If you look at reaction engines update it quite clearly states the engine is highly scalable ..

That is not at all what we have been told in the past - the typical issue that gets brought up being the cost of designing small hydrogen pumps.  So that would need clarification too.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/21/2016 07:33 am
Describing something as "highly scalable" doesn't preclude a minimum size. The current SABRE design is based around the Skylon D1 requirements, which are larger than the C2, those larger than the C1. the D2 requirements are driven by a commercial launch sweet spot, so while a desktop SABRE is not practical, a half-size one may be.
A 1/2 size Skylon would still be a very big beast indeed.
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It's my understanding the sub-scale demonstrator they are now proposing rather than being a full working engine, demonstrates the full cycle - e.g by being pressure fed instead of having the final engines fuel pumps
When did you see that information? Pressure fed was being talked about when Mark Hempsell was still with REL.

I'll note that what we know about SABRE 4 suggests it runs 2 separate combustion chambers (one inside the other?) If so they could run at substantially different chamber pressures. Chamber pressure, and hence head rise, is the problem with LH2 pump scaling.  If the ground tests run just past the air breathing / rocket transition (which they should because it's a key even) you might have a low(ish) pressure turbo pump for the air breathing then simulate the high pressure rocket part (briefly) with a pressure feed to demonstrate that with those flows and pressures cut over is smooth and controlled, even if it only runs a few seconds after switching to full rocket mode.

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What's with this Orbital Access deal? How can it possibly help them? Surely it would have to take full scale SABRE engines since they can't be made smaller?

If you look at reaction engines update it quite clearly states the engine is highly scalable ..

That is not at all what we have been told in the past - the typical issue that gets brought up being the cost of designing small hydrogen pumps.  So that would need clarification too.
Indeed.

I'd say there are a couple of ways those first few sentences found their way into the press release.

1)REL's PR is poorly vetted and loosely worded.  Not impossible. REL's never been that keen on talking to outsiders for the sake of doing so.

2)REL have reviewed their options and their funding and concluded scaling is not quite the issue they thought it was.

Which is of course much more interesting. Richard Varvills update to the BIS should be a hot ticket.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/21/2016 07:38 am
IMHO I think that Alan Bond and Reactions Engines had originally planned for a 'Rolls Royce' Development programme, but reality is now setting in and they have to go for the cheapest development programme they can get away with that proves what they need to prove.
It's always been the cheapest development plan they can implement.
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I have always thought that a £12 Bn development programme was just too expensive.  TBH I think the cost of the design and development should be halved to £6 Bn. 
The problem with that is what's called "Aerospace cost models." or Coste Estimating Relationships.  When backers do due diligence to decide if an idea is sensible they get someone to run one of these.

When they do so for a vehicle of 625 tonnes and about 15 tonnes payload out pops the £10Bn figure. When they run a similar model for the SUS it comes up about £2Bn. Hey presto£12bn.

Now when NASA ran the SX development programme through the favorite US version (IIRC up to the first F9 flight, and including the F1 series) it came up with $2Bn  :(

As you might guess these models institutionalize decades of cost plus government aerospace project overruns and government procurement practices, however they are what a banker would base their estimate of the size of the bag of cash needed to fund a project this size.  Anyone coming in with a figure substantially below the  model before doing the work would "clearly" have failed to factor in important parts of the project, otherwise their figure would be much closer to the model.

This means a)Raising that money will be very difficult b)If they succeed they should have substantial contingency funds to deal with unexpected problems.
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There are a whole new bunch of technologies that should help them reduce the cost since they first calculated the programme cost....  much more detailed and accurate advanced design & simulation software... 3D printing etc....   It is obvious to me that, that is why they have employed Mark Wood to focus on reducing costs
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...Chief Operating Officer & Engineering Director, with responsibility for operational leadership, improving the efficiency and effectiveness of the business through integration, collaboration and operational best practices.

Quite probably. You should also include the many collaborations that REL have undertaken with all sorts of people to raise the TRL of different parts of the design. REL are very good at leveraging partnerships.

I'm quite sure that having spent so long on this REL have a very well developed model of what they need to do and a "ground up" model of (roughly) what the real costs would be.

But that's just based on their collecting actual costings for the various parts of the task, whereas the CERs
(supposedly) pick up all the real world unexpected things that happen on lots of real projects. And SABRESkylon is sufficiently not a rocket or an aircraft that you cannot rely on the real (needed) budget being 1/5 what the model said SX's budget needed to be for the F1 and F9 programmes.

I believe the CER's for SABRESkylon are very conservative (most of the big vehicles in the data base will be large passenger aircraft, with lots of issues related to them carrying fare paying passengers from day 1 of their entering scheduled service) and run as a commercial programme the "Skylon Consortium" (whoever they turn out to be) can deliver Skylon at substantially less than the model cost.

But there's what I believe and what can be demonstrated through the CER and that's £10bn for SABRESkylon and £2bn for SUS.

IOW "Model says no."  :(

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 07/22/2016 07:54 am
So, on Friday Richard Varvill will deliver a Skylon Update to the BIS conference. What are they likely to say, and what would you want them to say?

Want them to say?

"we secured (X) customers who have put refundable deposits on our books so we can finally move towards airframe maker selection & speed up ground testing. We will deliver on schedule."

jokes aside, I would like them to develop over recent remarks that the ground test article is going to be "much cheaper originally expected". Is it due to cutting on costs, or is it due to early conservative estimates?
if the latter, is there any hope that (1) the already-confirmed cost reductions for the ground test articles are applicable to the real engines, and that (2) the overall cost estimates are equally conservative?
Could it also be because BAE will be providing a lot of the components without profit margins and sale tax. VAT is 20% cost reduction alone.
on intermediate products, VAT is usually refundable so it shouldn't impact costs... not sure how it works in UK however.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alpha_Centauri on 07/22/2016 03:45 pm
Don't suppose anyone was at the BIS talk today?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: A_M_Swallow on 07/23/2016 02:15 am
{snip} Could it also be because BAE will be providing a lot of the components without profit margins and sale tax. VAT is 20% cost reduction alone.
on intermediate products, VAT is usually refundable so it shouldn't impact costs... not sure how it works in UK however.

In the UK the seller only pays VAT on the price difference. These are exemptions for exports.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/23/2016 10:32 am
In a throw-away comment about the title slide, RV joked that PR had come to Reaction engines - the title wasn't anything an engineer would write "Reaction Engines / To Mach 5 and Beyond / the SABREtm solution.
Which suggests the comments about a "highly scaleable" engine in the press release was not loose writing by a PR hack.
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RV confirmed SABRE is designed to be a SSTO engine, but they're investigating TSTO concepts.
Hypersonic passenger transport is too expensive to be practical at the moment. Not going to go into other unmanned craft in this talk.
Wasn't thinking about other unmanned craft until this...
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They continued to use the same SABRE engine diagram as we've seen before, but RV was quite careful to use "This particular design" when describing it, and refer to it as the C1 engine. (with particular reference to the sub zero cooling, and the conical inlet closing shutters)

They are goig to build their own H2 test facility, and have quite detailed plans. (which didn't appear to have LOX tanks I only saw LH2, LHe and LN)
Which is unfortunate as that suggests they won't be investigating (even briefly) the air breathing/ rocket transition, which I'd suggest is a key point where SABRE does diverge from both turbojets and rockets and likely to be an area of "unknown unknowns."  :(
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The SABRE test engine begins at the compressor, has various heat exchangers but doesn't have thrust chambers. From the humanoid figure for scale it's about 4 feet high, five wide and ten deep,
Once the testing of the SABRE cycle is complete, the front and back will be added and testing of the integrated engine can be done. Once that's complete a test engine can be installed into a winged test vehicle and flown. Development of the test vehicle is expected to be around 1bn (I don't know if that's cumulative or additional to the engine costs)
That sounds like an upgraded Nacelle Test Vehicle but running a full airbreathing SABRE. Typically running it with one engine would give very different aerodynamics but I've just had a thought....

Build the test vehicle in the Skylon shape. Put the complete test engine in 1 nacelle and balence it with a straight rocket.  Obviously flights will be short due to high propellant burn but perhaps long enough to get the needed information.
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While too small for the propulsion systems, the National Propulsion Test Facility would probably come in useful for testing the RCS system.
Will this just be the RCS or are they talking the SOMA OMS engine? that' a fairly powerful little beast in its own right.
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REL are particularly hoping BAE can help with the analysis of the CFD at the back of the nacelle (I don't know if that's a reference to the plume issue, or the internal flow)
Could be either. NASA and DLR have mentioned plum [EDIT plume ]impingement on the rear fuselage as a possible concern and detailed airflow around all the rear plumbing is likely to be complex. It'd be terrible to discover the engine has too much drag when some slight layout changes in design could have fixed it.  :(
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Unrelated, Alan Bond is one of the most charismatic people I've met. I wouldn't trust myself to objectively judge anything he said.
Not too obvious on recordings but I suspect he's quite different without a camera in his face. :)

A more common observation is "Does not suffer fools gladly." This is likely to have made interfacing to some government departments quite tense on occasions.
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the C1 engine was designed to run at 100-200 bar, as is required for the high SI.
The air breathing engines in SABRE 4 are more likely to be around 20.
That should make the air breathing pump problems quite a bit easier but that still leaves what they will run the rocket chambers at.  AIUI it's the combination of high pressure rise and low volume that makes the LH2 pump design problem such a PITA.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 07/23/2016 10:37 am

Unrelated, Alan Bond is one of the most charismatic people I've met. I wouldn't trust myself to objectively judge anything he said.


I have heard him oncein person  and I wasn't sure about other people but he had that effect on me. He radiates competence and intelligent interest and so on.  I want very much to believe everything he says :-)

Anyhow it's an important skill and I'm sure SABRE/Skylon wouldn't have had the chances it has had without that.

Thanks very very much for your summary - there are some interesting things to digest.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: flymetothemoon on 07/23/2016 10:46 pm
Wasn't thinking about other unmanned craft until this...

Not even this one?

https://www.youtube.com/watch?v=cInXWApcbew

[...] plum impingement [...]

Ooh... Ouchie!  ;D ;)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: adrianwyard on 07/24/2016 12:18 am
A UAV with hypersonic plum impingement capability would be a war-winning weapon. I expect the USAF to write a cheque for full funding just as soon as they learn what plum is British slang for. :-)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Bob Shaw on 07/24/2016 12:28 am
Brexit may kill Skylon, as it would be a logical Ariane 7 and although ESA isn't an aspect of the EU most of the ESA money comes from the EU, and supports EU aerospace...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: gosnold on 07/24/2016 08:54 am
Brexit may kill Skylon, as it would be a logical Ariane 7 and although ESA isn't an aspect of the EU most of the ESA money comes from the EU, and supports EU aerospace...
The ESA money is for Sentinel and Galileo, not for the launcher program.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alpha_Centauri on 07/24/2016 10:27 am
Brexit may kill Skylon, as it would be a logical Ariane 7 and although ESA isn't an aspect of the EU most of the ESA money comes from the EU, and supports EU aerospace...

No, only roughly about ~20% is from the EU, and as per above the vast majority of that is for the Gallileo and Sentinel constellations. Launchers are not funded via the EU.

Besides Skylon was never actually going to be Ariane 7 as the French are the largest investor in launchers, and for obvious political reasons they were never going to sign up to a British idea where their space industry is reliant on a piece of British technology.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/24/2016 08:25 pm
Brexit may kill Skylon, as it would be a logical Ariane 7 and although ESA isn't an aspect of the EU most of the ESA money comes from the EU, and supports EU aerospace...

No, only roughly about ~20% is from the EU, and as per above the vast majority of that is for the Gallileo and Sentinel constellations. Launchers are not funded via the EU.

Besides Skylon was never actually going to be Ariane 7 as the French are the largest investor in launchers, and for obvious political reasons they were never going to sign up to a British idea where their space industry is reliant on a piece of British technology.
Actually Skylon is dependent on the French made Pyrosic material as much as Skylon would be dependent on SABRE. Each is a critical part of the concept.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: knowles2 on 07/25/2016 12:49 am
Brexit may kill Skylon, as it would be a logical Ariane 7 and although ESA isn't an aspect of the EU most of the ESA money comes from the EU, and supports EU aerospace...

No, only roughly about ~20% is from the EU, and as per above the vast majority of that is for the Gallileo and Sentinel constellations. Launchers are not funded via the EU.

Besides Skylon was never actually going to be Ariane 7 as the French are the largest investor in launchers, and for obvious political reasons they were never going to sign up to a British idea where their space industry is reliant on a piece of British technology.
Actually Skylon is dependent on the French made Pyrosic material as much as Skylon would be dependent on SABRE. Each is a critical part of the concept.

There UK Atomic Energy Authority SYTEM 2 material that REL and some universities was trying to reinvent. I suspect which ever material is chosen, given the size of the vehicle, a substantial investment in manufacturing will be required and therefore the decision will either be purely political, give the French the work to keep them happy or commercial which ever material is the best or which ever manufacture willing to invest in the project with capital and knowledge.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/25/2016 07:11 pm
Brexit may kill Skylon, as it would be a logical Ariane 7 and although ESA isn't an aspect of the EU most of the ESA money comes from the EU, and supports EU aerospace...

No, only roughly about ~20% is from the EU, and as per above the vast majority of that is for the Gallileo and Sentinel constellations. Launchers are not funded via the EU.

Besides Skylon was never actually going to be Ariane 7 as the French are the largest investor in launchers, and for obvious political reasons they were never going to sign up to a British idea where their space industry is reliant on a piece of British technology.
Actually Skylon is dependent on the French made Pyrosic material as much as Skylon would be dependent on SABRE. Each is a critical part of the concept.

There UK Atomic Energy Authority SYTEM 2 material that REL and some universities was trying to reinvent. I suspect which ever material is chosen, given the size of the vehicle, a substantial investment in manufacturing will be required and therefore the decision will either be purely political, give the French the work to keep them happy or commercial which ever material is the best or which ever manufacture willing to invest in the project with capital and knowledge.
This has no French government involvement. It'a French company making a product. Outside the material Skylon's design is quite conventional, including the size of panels that need to be made. IIRC the ring spacing for the full size Skylon is 0.3m. The panels only grow if they get longer. I think mfg of this size is well within the scale of the French operation.  Wheather they can make enough of them fast enough without substantial scaling up is another matter.  Retaining that standard size would result in a smaller vehicle with fewer panels.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: guckyfan on 07/26/2016 08:56 am
Outside the material Skylon's design is quite conventional,

That's like the Wright brothers lookin at a 747 and saying "Outside the material and engines this design is quite conventional"
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Dalhousie on 07/26/2016 09:42 am
Brexit may kill Skylon, as it would be a logical Ariane 7 and although ESA isn't an aspect of the EU most of the ESA money comes from the EU, and supports EU aerospace...

ESA money supports ESA Aerospace.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 07/28/2016 05:53 pm
Outside the material Skylon's design is quite conventional,

That's like the Wright brothers lookin at a 747 and saying "Outside the material and engines this design is quite conventional"

Just to be clear, that actually IS what they would say if they saw a 747 and it was explained and demonstrated for them. They weren't stupid, (rather stubborn, more than a little vain, and certainly grasping and vindictive, but NOT stupid) and would have easily realized how its operation compared to their own work. It was the direction their own work was going and obvious by the work of others around them. There are details that they would have trouble understanding at first because of their knowledge base, but in general they'd see the 747 layout as very 'conventional',  requiring advanced materials and propulsion far in advance of what they had available certainly but recognizable from their own knowledge.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: CameronD on 07/29/2016 12:01 am
...... There are details that they would have trouble understanding at first because of their knowledge base, but in general they'd see the 747 layout as very 'conventional',  requiring advanced materials and propulsion far in advance of what they had available certainly but recognizable from their own knowledge.

Mebbe add 'controls' to that list.  The Wright brothers didn't invent the joystick/rudder pedals (that came later over in Europe) so they wouldn't recognise anything in the cockpit either.  :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: high road on 07/29/2016 11:24 am
...... There are details that they would have trouble understanding at first because of their knowledge base, but in general they'd see the 747 layout as very 'conventional',  requiring advanced materials and propulsion far in advance of what they had available certainly but recognizable from their own knowledge.

Mebbe add 'controls' to that list.  The Wright brothers didn't invent the joystick/rudder pedals (that came later over in Europe) so they wouldn't recognise anything in the cockpit either.  :)

The fly-by-wire and autopilot function (even when not on the actual autopilot) that are part of current controls are even more important developments that allow airplane sizes and flight lengths that would be prohibitively taxing for pilots with direct mechanical control. That is something that would be hard to explain to them from their 19th - early 20th century reference. (well, they'd probably think it's an actual AI flying the plane).

New material, new engines, smaller wings than ever before (while still functioning as an airplane), dedicated landing strips, 'detachable' carbo bay that can be preloaded and quickly swapped upon landing... About as run-off-the-mill as, say, Thunderbird II. (That one can even land propulsively. Best of both worlds :p)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/29/2016 11:18 pm
...... There are details that they would have trouble understanding at first because of their knowledge base, but in general they'd see the 747 layout as very 'conventional',  requiring advanced materials and propulsion far in advance of what they had available certainly but recognizable from their own knowledge.

Mebbe add 'controls' to that list.  The Wright brothers didn't invent the joystick/rudder pedals (that came later over in Europe) so they wouldn't recognise anything in the cockpit either.  :)
The Wright brothers in 1903 probably. By 1913 (by which time Bleriot had flown the English Channel) they would recognize a control wheel with rudder and flaps.

The fly-by-wire and autopilot function (even when not on the actual autopilot) that are part of current controls are even more important developments that allow airplane sizes and flight lengths that would be prohibitively taxing for pilots with direct mechanical control. That is something that would be hard to explain to them from their 19th - early 20th century reference.
In 1903 maybe, by 1914 Sperry had already demonstrated an autopilot

https://en.wikipedia.org/wiki/Lawrence_Sperry.

IIRC By 1920 the word "Drone" had already been seen in science fiction stories by EE Smith and small radio controlled aircraft were in use as gunnery targets by the early 1920's.
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(well, they'd probably think it's an actual AI flying the plane).
Wrong. Explaining electronics that complex would be difficult, but the concept would be there.  This technology has been around for a lot longer than you seem to realize.
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New material, new engines, smaller wings than ever before (while still functioning as an airplane),
Wing loading for the MD MD11F was 844 Kg/m^2. That was for a passenger carrying airliner. I don't have  a figure for wing area for Skylon but anything above 386 m^2 would put it's wing loading below that.
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dedicated landing strips,
Wrong again. A dedicated launch runway to orbit, but in air breathing only mode Skylon can take off from a much wider range of runways. Most of the length is to meet emergency stop criteria for the fully loaded vehicle, which only apply when it's fully loaded to go to orbit. Landing is much easier with a low empty weight and no engine noise issues.
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'detachable' carbo bay that can be preloaded and quickly swapped upon landing...
Much like how most passenger luggage is shipped in fact.
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About as run-off-the-mill as, say, Thunderbird II. (That one can even land propulsively. Best of both worlds :p)
You really need to either read up on what Skylon or stop putting up so many strawman arguments.   :(

For those who don't really know that much about Skylon I'll say it's designed like the SR71 to be as radical as it needs to be (in terms of materials and systems) to get the job done. 

REL are very conscious of the perception (and actual) level of risk of the project. Outside of the critical areas needed to make it work they have aimed to go with the most boring mature technology possible. This explains why they went with riveting for examples, despite the huge advances in adhesives. They are confident they can make (and test) rivets in the size and shape needed to do the job, whereas an adhesive that can provably operate over the full Earth to space pressure / temperature range is likely a major research project on its own.  Likewise AFAIK the tanks are spec at a regular Al alloy, not AlLi. Mfg of such tanks is fairly widespread, while AlLi is a niche material and it's not needed to get the job done.

But the top level story. It's a twin engine low wing monoplane with a payload bay in the mid body made by riveting skin panels to a framework which takes off and lands horizontally, like a few thousand other designs in the last 100 years but unlike the only 3 partially reusable space vehicles that have flown.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 07/30/2016 01:13 am
[Wright Bros and 747s.]

The point of that analogy was that the 747 flies by principles understood in the first decade of aviation, in spite of still being completely and utterly impossible to build at the time.

'detachable' carbo bay that can be preloaded and quickly swapped upon landing...
Much like how most passenger luggage is shipped in fact.

No aircraft uses a detachable cargo section that must function as an integrated part of the vehicle. ULD's are not even remotely analogous.

It's that kind of exaggeration that makes people so sceptical of the continual claims that Skylon has no "showstoppers".

[The only aircraft I've seen with detachable cargo-pod was the failed Fairchild XC-120 "Packplane".]
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 07/30/2016 01:18 am
It's that kind of exaggeration that makes people so sceptical of the continual claims that Skylon has no "showstoppers".

For that matter, it's why I detest the constant use of the phrase "no showstoppers" in aerospace. As if "theoretically within the laws of physics, as far as we can tell, having never done anything remotely like it before" is the sole criteria for the practicality of a design.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 07/30/2016 06:24 am
It's that kind of exaggeration that makes people so sceptical of the continual claims that Skylon has no "showstoppers".

For that matter, it's why I detest the constant use of the phrase "no showstoppers" in aerospace. As if "theoretically within the laws of physics, as far as we can tell, having never done anything remotely like it before" is the sole criteria for the practicality of a design.

This is an unproductive argument about tone and semantics. With the work that has been done so far no insurmountable problems have been found. It's trivially self-evident that problems can turn up as development proceeds.   It's also quite possible for quite surmountable problems to kill off an effort which runs out of money.  This is all quite different from ideas which have known problems.

We are really interested in whether Skylon/SABRE proceeds or not and what will happen if it does. 
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/30/2016 07:01 am

'detachable' carbo bay that can be preloaded and quickly swapped upon landing...
Much like how most passenger luggage is shipped in fact.

No aircraft uses a detachable cargo section that must function as an integrated part of the vehicle. ULD's are not even remotely analogous.

It's that kind of exaggeration that makes people so sceptical of the continual claims that Skylon has no "showstoppers".

[The only aircraft I've seen with detachable cargo-pod was the failed Fairchild XC-120 "Packplane".]
I used the phrase "passenger luggage" very specifically to denote the sort of boxes used to speed up passenger luggage handling at airports

https://en.wikipedia.org/wiki/Unit_load_device

It's that kind of superficial, badly researched knee jerk criticism that makes me suspect I'm dealing with a doubter, not a sceptic.  :( If you're a sceptic you can explain exactly what areas you have concerns about.  "It can't be done" is the hall mark of doubter, who will never be convinced it's possible till it happens.

As for "no showstoppers" that paraphrases the professional opinion of the ESA technical centre, with full access to the SABRE technology and the Skylon development plan.

So you're entitled to your opinion, but the opinion of people who do this for a living is that it can be done. provided the engine meets it's T/W and Isp specs (and they are confident that is viable) and the structures can be made with the strength to weight ratio and thermal properties needed.

Pretty much like any large engineering development in fact.  :(

SABRESkylon is a high risk/high cost/high reward programme that give customers, actual payload users, something they simply won't get from any conventional rocket system, even a semi reusable one.

A launch vehicle to take their payloads, on  their schedule to orbit. If it fails they get the payload back in 1 piece and if they run out of payloads to launch they can sell it to someone else.

It's only that the rocket launch services "business rules" are so mad compared to every other transport mode in existence that this notion is viewed with such suspicion   :(

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 07/30/2016 10:30 am
'detachable' carbo bay that can be preloaded and quickly swapped upon landing...
Much like how most passenger luggage is shipped in fact.
No aircraft uses a detachable cargo section that must function as an integrated part of the vehicle. ULD's are not even remotely analogous.
I used the phrase "passenger luggage" very specifically to denote the sort of boxes used to speed up passenger luggage handling at airports
https://en.wikipedia.org/wiki/Unit_load_device

I'm curious what you believed the highlighted part of my comment was referring to?

As for "no showstoppers" that paraphrases the professional opinion of the ESA technical centre, with full access to the SABRE technology and the Skylon development plan.

Rolls-Royce and British Aerospace thought the same thing about the inherently flawed HOTOL design. As did the UK government for 6 years.

Similar "no showstoppers" claims were made about similarly flawed designs, from NASP to X-33. Likewise JWST, as is slips multiples overbudget. Likewise there are "no showstoppers" with SLS today nor were there with Ares before it. And "no showstoppers" with the launch of Orion on a modified SRB launcher and now on an SRB-boosted launcher.

You wonder why whenever I hear that phrase, I expect the best-case scenario is that the project will merely go several times over-budget and deliver a fraction of what was promised, but more likely fail completely.

SABRESkylon is a high risk/high cost/high reward programme

But if anyone but a True Believer says that, we get lectured at.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: francesco nicoli on 07/30/2016 11:30 am
'detachable' carbo bay that can be preloaded and quickly swapped upon landing...
Much like how most passenger luggage is shipped in fact.
No aircraft uses a detachable cargo section that must function as an integrated part of the vehicle. ULD's are not even remotely analogous.
I used the phrase "passenger luggage" very specifically to denote the sort of boxes used to speed up passenger luggage handling at airports
https://en.wikipedia.org/wiki/Unit_load_device

I'm curious what you believed the highlighted part of my comment was referring to?

As for "no showstoppers" that paraphrases the professional opinion of the ESA technical centre, with full access to the SABRE technology and the Skylon development plan.

Rolls-Royce and British Aerospace thought the same thing about the inherently flawed HOTOL design. As did the UK government for 6 years.

Similar "no showstoppers" claims were made about similarly flawed designs, from NASP to X-33. Likewise JWST, as is slips multiples overbudget. Likewise there are "no showstoppers" with SLS today nor were there with Ares before it. And "no showstoppers" with the launch of Orion on a modified SRB launcher and now on an SRB-boosted launcher.

You wonder why whenever I hear that phrase, I expect the best-case scenario is that the project will merely go several times over-budget and deliver a fraction of what was promised, but more likely fail completely.




you are free of taking whatever conclusion suits your intelligence.... simiarly, we are free to take a formally stated opinion from ESA in higher consideration than an anonimous comment on the web. No offense, of course.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/30/2016 05:15 pm
Rolls-Royce and British Aerospace thought the same thing about the inherently flawed HOTOL design. As did the UK government for 6 years.
With the benefit  of 20/20 hindsight of course.  HOTOL taught the REL design teams lessons which others still seem either unwilling or unable to recognize. Whenever I see a VTOHL concept without a drop tank and SRB's to loose mass I think "You have no idea what the pitching moments from that are going to be, do you?"
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Similar "no showstoppers" claims were made about similarly flawed designs, from NASP to X-33. Likewise JWST, as is slips multiples overbudget. Likewise there are "no showstoppers" with SLS today nor were there with Ares before it. And "no showstoppers" with the launch of Orion on a modified SRB launcher and now on an SRB-boosted launcher.
You missed out "Compute our way to orbit," a favorite of the X30 programme.

That burned through $1Bn+ of US taxpayers money before any independent assessment of the science behind it.  Had that been done it never would have been Green lit as it had so many holes in it.

SABRESkylon has had that assessment and there are no holes.  I've not seen any such assessment done of any competitors. 

In particular I'm still looking forward to seeing how SX will make their BFR a fully reusable TSTO when they said they could with F9, but in fact can't.
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You wonder why whenever I hear that phrase, I expect the best-case scenario is that the project will merely go several times over-budget and deliver a fraction of what was promised, but more likely fail completely.
I think we get it. Thank you for clarifying.
Quote
But if anyone but a True Believer says that, we get lectured at.
I think you'll find it's when people make badly researched knee jerk comments they get reminded of the facts.

Big risk, big gains. Anyone who tells you different is either rigging the game or about to take you for a bag of cash.

Do what you always do, get what you always get.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 07/31/2016 03:35 am
Rolls-Royce and British Aerospace thought the same thing about the inherently flawed HOTOL design. As did the UK government for 6 years.
With the benefit  of 20/20 hindsight of course.  HOTOL taught the REL design teams lessons which others still seem either unwilling or unable to recognize.

...then you immediately say...

In particular I'm still looking forward to seeing how SX will make their BFR a fully reusable TSTO when they said they could with F9, but in fact can't.

You don't see the double-standard here?

One failed project gives REL innovation superpowers, but SpaceX deciding not to pursue US-reusability for F9 somehow means the opposite.

A group that has never delivered a completed launcher, or aircraft, or analogous project, working on a design that has never been built, of a type (SSTO) that is a graveyard of failed designs, is seen as beyond criticism. Because they have Experience! Meanwhile a company that has successfully built and operated two launchers in a decade, recovered both the first stage and cargo-capsule, is assumed to be incompetent when it comes to scaling up because they decided the numbers on a single sub-project didn't work, before they'd spent a dime on itsdevelopment.

[Personally, I'd be shocked if SpaceX can pull off the BFR booster alone within a decade, forget the rest of MCT, not to mention the rest of Mars-side infrastructure. They seem to be skipping over too many steps between here-and-there. (IMO, taking too big a leap caused some of the early issues with F9.) But using the F9-US as a reason for scepticism is nuts.]

fully reusable TSTO when they said they could with F9, but in fact can't.

...and speaking of poorly researched.

Big risk, big gains. Anyone who tells you different is either rigging the game or about to take you for a bag of cash.
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SABRESkylon has had that assessment and there are no holes.

You go from "Big Risk" to "There are no holes!" within even a single post.

Which was my point. When a non-believer points out the risk (and the cost), they get lectured. The ESA has done an assessment! The ESA! REL has eliminated every risk! Every remaining part is off-the-shelf, low-risk, industry standard! Who are you to dare suggest Skylon is a high-risk concept?! Vested interests!
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Robotbeat on 07/31/2016 03:55 am
...

In particular I'm still looking forward to seeing how SX will make their BFR a fully reusable TSTO when they said they could with F9, but in fact can't. ...
"In fact," you are false.

You've repeated this distortion many times.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/31/2016 08:30 am
Rolls-Royce and British Aerospace thought the same thing about the inherently flawed HOTOL design. As did the UK government for 6 years.
With the benefit  of 20/20 hindsight of course.  HOTOL taught the REL design teams lessons which others still seem either unwilling or unable to recognize.

...then you immediately say...

In particular I'm still looking forward to seeing how SX will make their BFR a fully reusable TSTO when they said they could with F9, but in fact can't.

You don't see the double-standard here?

One failed project gives REL innovation superpowers, but SpaceX deciding not to pursue US-reusability for F9 somehow means the opposite.

A group that has never delivered a completed launcher, or aircraft, or analogous project, working on a design that has never been built, of a type (SSTO) that is a graveyard of failed designs, is seen as beyond criticism. Because they have Experience! Meanwhile a company that has successfully built and operated two launchers in a decade, recovered both the first stage and cargo-capsule, is assumed to be incompetent when it comes to scaling up because they decided the numbers on a single sub-project didn't work, before they'd spent a dime on itsdevelopment.

[Personally, I'd be shocked if SpaceX can pull off the BFR booster alone within a decade, forget the rest of MCT, not to mention the rest of Mars-side infrastructure. They seem to be skipping over too many steps between here-and-there. (IMO, taking too big a leap caused some of the early issues with F9.) But using the F9-US as a reason for scepticism is nuts.]

fully reusable TSTO when they said they could with F9, but in fact can't.

...and speaking of poorly researched.

Big risk, big gains. Anyone who tells you different is either rigging the game or about to take you for a bag of cash.
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SABRESkylon has had that assessment and there are no holes.

You go from "Big Risk" to "There are no holes!" within even a single post.

Which was my point. When a non-believer points out the risk (and the cost), they get lectured. The ESA has done an assessment! The ESA! REL has eliminated every risk! Every remaining part is off-the-shelf, low-risk, industry standard! Who are you to dare suggest Skylon is a high-risk concept?! Vested interests!

But it does seem Space X gets a free pass from criticism on here by some yet REL gets told that will never happen, perhaps some tire of the double standards expressed.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Alpha_Centauri on 07/31/2016 06:50 pm
But it does seem Space X gets a free pass from criticism on here by some yet REL gets told that will never happen, perhaps some tire of the double standards expressed.
As much as I hate a lot of the idiotic SpaceX amazing peopleism on here, which is why i don't post very often anymore, at least SpaceX are flying stuff...
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 07/31/2016 08:18 pm
But it does seem Space X gets a free pass from criticism on here by some yet REL gets told that will never happen, perhaps some tire of the double standards expressed.
As much as I hate a lot of the idiotic SpaceX amazing peopleism on here, which is why i don't post very often anymore, at least SpaceX are flying stuff...

But then their financial path has been clearer than the winding labyrinth that REL seem to have been expected to walk to get their money.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 07/31/2016 09:48 pm
One failed project gives REL innovation superpowers, but SpaceX deciding not to pursue US-reusability for F9 somehow means the opposite.
Interesting use of language.

I'd say SX's failure to make F9 upper stage reuse work will be as crucial to their growth as the REL teams inability to make HOTOL work, specifically in the insight it gives them. That sounds rather more balanced.
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A group that has never delivered a completed launcher, or aircraft, or analogous project, working on a design that has never been built, of a type (SSTO) that is a graveyard of failed designs, is seen as beyond criticism.
Most of whose attempts have been in the  VTOL mode, the most difficult way to do this task. As for "beyond criticism" could you stop with the strawmen? if you have actual areas you think they are wrong spell them out.
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Because they have Experience! Meanwhile a company that has successfully built and operated two launchers in a decade, recovered both the first stage and cargo-capsule, is assumed to be incompetent when it comes to scaling up because they decided the numbers on a single sub-project didn't work, before they'd spent a dime on itsdevelopment.
Except no scaling was meant to be needed to make full reuse work for F9, was it?   :(

As for confidence. We know 3 vehicles have demonstrated winged reentry from full LEO velocity. There is no track record of any conventionally shaped upper stage coming in from full LEO velocity. I can think of several good reasons why it it will never be viable while delivering a useful payload to orbit without orders of magnitude improvements in materials to make this mode work due to the compromises it will take to make the stage survive and be able to be reused.

However this is off topic for this thread.

So apart from some phraseolgy you find annoying what real complaints do you have about SABRESkylon?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Vultur on 08/01/2016 03:06 am
I'd say SX's failure to make F9 upper stage reuse work

I don't think they did fail to make it work; they decided not to try, which isn't the same thing. Musk said, IIRC, that it wasn't practical for such a low-specific-impulse second stage when most of the market is in GTO.

FH will have more margin, anyway, so if they want to pursue second stage reusability for LEO with their commsat constellation, it'd probably be on FH.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Dalhousie on 08/01/2016 11:45 am
I come to this thread to read about Sabre and Skylon, not endless rehashing of how SpaceX is better than everything.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: hkultala on 08/01/2016 01:22 pm

As for confidence. We know 3 vehicles have demonstrated winged reentry from full LEO velocity. There is no track record of any conventionally shaped upper stage coming in from full LEO velocity.

None of your 3 winged vehicles have been real upper stages with full-size tanks. 1 was only a payload that was lifted all the way up to orbit with a rocket, 1 was payload with just very small apogee engines, and had the main engines of the upper stage but lacked the fuel tank.

And there are also much greater amount of wingless capsules that have demonstrated re-entry from full LEO velocity, at least two also from much higher velocities.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: oddbodd on 08/01/2016 02:50 pm

As for confidence. We know 3 vehicles have demonstrated winged reentry from full LEO velocity. There is no track record of any conventionally shaped upper stage coming in from full LEO velocity.

None of your 3 winged vehicles have been real upper stages with full-size tanks. 1 was only a payload that was lifted all the way up to orbit with a rocket, 1 was payload with just very small apogee engines, and had the main engines of the upper stage but lacked the fuel tank.

And there are also much greater amount of wingless capsules that have demonstrated re-entry from full LEO velocity, at least two also from much higher velocities.

None of your many wingless capsules have been real upper stages with full-size tanks or full-size engines.

There. Fixed it for you.

I look at a small stubby conical crew module with a large heat shield, and compare to an upper stage, a tall cylinder with engines at one one end, and it would seem different enough to bear no relation:
* Presumably won't come in sideways for all sorts of reasons.
* Heat shield on top with head first reentry? Surely the lack of cone shape will bring the side-spilling hot gases into contact with the relatively fragile cylinder? Would also be very unstable due to COG of engines at bottom/rear.
* Engine first rentry? Surely this will cause damage to the engines as well as the cylindrical shell?
* Fully powered deorbit into atmosphere, engine off then powered landing ala current reusable first stage? Surely would take an enormous amount of fuel, killing payload margins? Also, the cylinder would spend a prolonged period passing through its own hot exhaust.

I can look at the shuttle and Skylon, and see that the underlying principle is the same. Heat shield on a winged vehicle, correct angle of attack, with relatively small mass to large surface area, vehicle slows, then glides in to land. Purely on the reentry heating DLR in Germany have anaylsed the reentry of a Skylon and say that the heating is less than that of the Shuttle because... science! math! CFD! Germans!
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 08/01/2016 03:16 pm
...... There are details that they would have trouble understanding at first because of their knowledge base, but in general they'd see the 747 layout as very 'conventional',  requiring advanced materials and propulsion far in advance of what they had available certainly but recognizable from their own knowledge.

Mebbe add 'controls' to that list.  The Wright brothers didn't invent the joystick/rudder pedals (that came later over in Europe) so they wouldn't recognise anything in the cockpit either.  :)

Actually they understood them and even tried to 'include' them in their patent fight as "natural extensions" of the concept of "control" itself. The Wright's were well aware of the limitations to wing-warping but they backed themselves into a corner. Again, they weren't stupid... Just jerks :)


As for confidence. We know 3 vehicles have demonstrated winged reentry from full LEO velocity. There is no track record of any conventionally shaped upper stage coming in from full LEO velocity.

None of your 3 winged vehicles have been real upper stages with full-size tanks. 1 was only a payload that was lifted all the way up to orbit with a rocket, 1 was payload with just very small apogee engines, and had the main engines of the upper stage but lacked the fuel tank.

And there are also much greater amount of wingless capsules that have demonstrated re-entry from full LEO velocity, at least two also from much higher velocities.

Point? None of the capsules had "full-size" integral tanks either and while "aren't going to try" and "can't" are not the same the main point was it was not as "easy" as it was presented as being which SpaceX keeps finding out is the case. Elon Musk has acknowledged things are in fact harder to do than he assumed, though that doesn't stop him from continuing to do so :)

So far we've seen a booster stage that only reaches a fraction of orbital velocity recovered successfully, or "payloads" that have been specifically designed and constructed to survive but in turn require being more robust and heavy structures to ensure that survival.

We know what works, we also know what SHOULD work but have yet to prove that it does and quite often that 'proof' can work either way in the end. But the simple and basic fact is that there needs to be multiple methods and designs tried and tried again as there is obviously no ONE "right" way to do this.

Arguing about the general and specific details of a proposed design is one thing, arguing about the relative ability of any 'team' to bring a design to fruition is not helpful at all. If we're going to discuss actual issues with Skylon, then lets. Otherwise comparisons and contrasts between REL and SpaceX should be limited to another thread.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Rocket Science on 08/01/2016 03:40 pm
Really "epic" patent fight "Wright vs Curtis", folks should google it... :)
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: RanulfC on 08/01/2016 03:44 pm
Really "epic" patent fight "Wright vs Curtis", folks should google it... :)

And costly as well. "Birdmen" (https://www.amazon.com/Birdmen-Wright-Brothers-Curtiss-Control/dp/0345538056/ref=sr_1_1?s=books&ie=UTF8&qid=1470066111&sr=1-1&keywords=birdmen) makes a good case that the feud managed to set American aviation back a huge amount as well as the Wright's insistence on a complete monopoly on "aircraft" (world wide no less) for at least a decade.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 08/01/2016 04:25 pm
I can look at the shuttle and Skylon, and see that the underlying principle is the same. Heat shield on a winged vehicle, correct angle of attack, with relatively small mass to large surface area, vehicle slows, then glides in to land. Purely on the reentry heating DLR in Germany have anaylsed the reentry of a Skylon and say that the heating is less than that of the Shuttle because... science! math! CFD! Germans!
Indeed. This is where keeping the LH2 tank inside the vehicle pays off. Yes it's a very big vehicle, but once the tanks empty it's a very light vehicle (and with much better aerodynamics to begin with) so it can start to decellerate higher, and more gently. Tougher to build, easier to fly.

And costly as well. "Birdmen" (https://www.amazon.com/Birdmen-Wright-Brothers-Curtiss-Control/dp/0345538056/ref=sr_1_1?s=books&ie=UTF8&qid=1470066111&sr=1-1&keywords=birdmen) makes a good case that the feud managed to set American aviation back a huge amount as well as the Wright's insistence on a complete monopoly on "aircraft" (world wide no less) for at least a decade.
Wow, what an epic sense of entitlement those guys had.  :(
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 08/01/2016 06:02 pm
On a general point I can see why some people can't deal with the paradox of people having confidence in a design yet still calling it high risk at the same time.

At heart it's the difference between science and engineering. It's also about the credibility of a team working on something versus a knowledgeable (in the subject) team (but not working on that particular problem) saying the (first) team can do something. 

Science searches for the detail rules that build the universe.  Engineering uses the rules that have been found to solve specific problems.

A scientist who can only explain 1/2 of why something works as it does is a very unhappy person. An engineer would ask "does that that explain enough of the phenomena involved to let me build what I want?"

What the ESTEC team and the symposium attendees agreed on is that REL have a) A clear path from what they have built to what they want to build and b) that it involves no new science. Existing models and design tools are good enough to build the vehicle with a high degree of confidence that it will work.

A classic contrast would be with the X30 programme (I could suggest others), where the PI asserted that the design tools of the time were good enough to build it with no independent confirmation. Likewise that the science was well enough understood to design a fuel injector that would mix, ignite and burn the fuel in the time it took to flow over the under surface of the vehicle.

Neither of these assertions was true (along with various others, as Heppleheimers book describes). The result was like trying to do brain surgery with a razor sharp but very floppy scalpel.  :( Once an independent inspection of the NASP programme was done it was effectively dead.

People who understand engineering and who've dug into REL's programme (as the ESTEC team did, including full disclosure of the then secret frost control system) feel the science is understood well enough by REL that the engine and the vehicle will do what they say it will do.

The "high risk" part of comes from the difference between what can be done (IE does not violate chemical or physical laws) and making it work.

Leonard De Vici knew that better, cheaper  bearings would have a major effect on how well machinery ran IE he understood the science well enough to recognize there benefits. But he did not have the engineering to make them good enough on a big enough scale (and hence cheap enough for mass use) to deliver any ideas he might have had for using them.

For SABRESkylon the risk starts with wheather they can raise all the money the cost models say you need for the project. This is the biggest risk since inadequate funding reduces margins for coping with unknown problems.

SABRE and Skylon are very large systems with lots of parts and lots of interactions between the parts.
Can they be made at the price, quality and volume levels needed?
Can they be assembled at the rate needed to deliver a vehicle before the money runs out?
Will testing reveal unexpected interactions between systems (probably)?
If harmful problems are found can work arounds be found?
Will the work arounds so damage the capabilities of the vehicle to make it unsaleable or economically unusable?

The open ended nature of some of those risks is what makes the SABRESkylon programme "high risk"

If some of the up-front risks materialize the programme never starts (or cripple it critically later on) while some of the later ones could kill it right at the last hurdle and you will only know you've succeeded when the last Skylon needed to break even has been sold. 

I hope that explains how people can both be confident that SABRESkylon can work (IE no new science and no impossible physics involved) but also be conscious that there is still a very large degree of risk in making it work.

The payoff. Countries, corporations or even (very) wealthy individuals can acquire on-demand launch of their payloads (or themselves  :) if they are happy to take the risk) with a safety record  orders of magnitude above what they could ever develop for themselves of up to 15tonnes to LEO, more than 5 tonnes to GTO with a reusable tug and several tonnes to escape velocity (letting you run your own Moon/Mars/Venus/Wherever exploration programme) , and recover a chunk of their investment if they run out of payloads to launch by simply selling it to someone else.

It's a rule that VC funders invest in the team, not the details of an idea. To date the REL team has shown that when fully funded they have delivered what they promised roughly when they promised it and coped with any issues along the way.  That includes a great many other side projects run with other partners to develop and verify various SABRE specific parts. Those projects only appear as single slides in their summary presentations but demonstrate that REL has run a great many more projects than most people realize.  The SABRE ground demonstration will not be their first trip round the block by a very long way.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Lars-J on 08/01/2016 06:58 pm
But it does seem Space X gets a free pass from criticism on here by some yet REL gets told that will never happen, perhaps some tire of the double standards expressed.

The "double standard" is due to one group actually building and flying real hardware, whereas the other group only has managed to build test hardware of small components, all the while claiming that there "are no showstoppers" for building something much better.

Which group do you think would naturally be taken more seriously?
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 08/01/2016 07:25 pm
But it does seem Space X gets a free pass from criticism on here by some yet REL gets told that will never happen, perhaps some tire of the double standards expressed.

The "double standard" is due to one group actually building and flying real hardware, whereas the other group only has managed to build test hardware of small components, all the while claiming that there "are no showstoppers" for building something much better.

Which group do you think would naturally be taken more seriously?

That's a far from fair comment being as REL have had to traverse a literal labyrinth to obtain the financing they have so far unlike Space X.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Lars-J on 08/01/2016 07:49 pm
But it does seem Space X gets a free pass from criticism on here by some yet REL gets told that will never happen, perhaps some tire of the double standards expressed.

The "double standard" is due to one group actually building and flying real hardware, whereas the other group only has managed to build test hardware of small components, all the while claiming that there "are no showstoppers" for building something much better.

Which group do you think would naturally be taken more seriously?

That's a far from fair comment being as REL have had to traverse a literal labyrinth to obtain the financing they have so far unlike Space X.

It may not be "fair", but it is accurate. Fairness has nothing to do with it. And SpaceX has not had an "easy street" either.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Star One on 08/01/2016 09:04 pm
But it does seem Space X gets a free pass from criticism on here by some yet REL gets told that will never happen, perhaps some tire of the double standards expressed.

The "double standard" is due to one group actually building and flying real hardware, whereas the other group only has managed to build test hardware of small components, all the while claiming that there "are no showstoppers" for building something much better.

Which group do you think would naturally be taken more seriously?

That's a far from fair comment being as REL have had to traverse a literal labyrinth to obtain the financing they have so far unlike Space X.

It may not be "fair", but it is accurate. Fairness has nothing to do with it. And SpaceX has not had an "easy street" either.

They have compared to REL.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: t43562 on 08/01/2016 09:58 pm
Could the mods please delete this pointless discussion please! It's not about Skylon
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Paul451 on 08/02/2016 02:53 am
I come to this thread to read about Sabre and Skylon, not endless rehashing of how SpaceX is better than everything.

It's interesting that John Smith 19 "liked" that comment, since I've noticed that he is always the one who initially brings up SpaceX in this thread. Others merely respond.

As for confidence. We know 3 vehicles have demonstrated winged reentry from full LEO velocity.

And that's the sort of exaggeration that makes everything else you say suspect. There's no analogous relationship between the Skylon design and the two round-nosed, stubby-body, delta-wing orbiters (STS/Buran), nor with the tiny little X-37 spaceplane.

Skylon is an entirely new untried dissimilar design. You can't just say "Oo, look, wings" and expect anyone to take you seriously.

(As Lars-J notes, it'd be like comparing a reusable upper-stage and a capsule, "Oo, look, wingless". There's just no comparison. And Lars could have also added a re-entry body for a warhead. Or even those three winged re-entry vehicles: They have as much similarity, from a physics standpoint, to a reusable upper-stage as they have to Skylon. (Ie, none.))

On a general point I can see why some people can't deal with the paradox of people having confidence in a design yet still calling it high risk at the same time.

Firstly, if you are going to address a comment to me, address it to me. "Some people" is just passive aggressive nonsense.

Secondly, you couldn't have missed my point more if you'd deliberately got into a car and travelled in the opposite direction until you hit ocean.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: high road on 08/02/2016 08:42 am
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New material, new engines, smaller wings than ever before (while still functioning as an airplane),
Wing loading for the MD MD11F was 844 Kg/m^2. That was for a passenger carrying airliner. I don't have  a figure for wing area for Skylon but anything above 386 m^2 would put it's wing loading below that.

With a length of 82 meters, and the design on wikipedia remotely to scale, it's considerably less, indeed. That's the point of a SSTO. Smaller wings, less mass to haul along. Which means a higher cruising speed to compensate for the smaller wings.

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dedicated landing strips,
Wrong again. A dedicated launch runway to orbit, but in air breathing only mode Skylon can take off from a much wider range of runways. Most of the length is to meet emergency stop criteria for the fully loaded vehicle, which only apply when it's fully loaded to go to orbit. Landing is much easier with a low empty weight and no engine noise issues.

That's what I said. The Skylon needs a dedicated runway to get to orbit. Using the SABRE engine for an airplane doesn't require the Skylon design.

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'detachable' carbo bay that can be preloaded and quickly swapped upon landing...
Much like how most passenger luggage is shipped in fact.

Oh yeah, last time I took the airplane, the preloaded cargo bay was inserted into the plane. Totally forgot about that one. And after that, the passenger cabin was attached to the wings that had just landed. No reason to wait to board until the previous passengers had gotten off.

Wait, that design also exists only on the drawing board. (I've tried finding the thread, but no such luck. Apparently, I didn't post in it).

Quote
On a general point I can see why some people can't deal with the paradox of people having confidence in a design yet still calling it high risk at the same time.

Curious statement, coming from the man who's arguing that there's nothing that revolutionary about the Skylon. Personally, I think it has quite a few new features, that'll require a lot of funding to get the kinks out. It's high risk, with possible high gain (as you said yourself, very confusing compared to the post I quoted above). Will it fly? Who knows. Personally, I'm not going into that one until there's a full scale model of the SABRE engine. Otherwise, there's nothing but opinion to argue with.

Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: hkultala on 08/02/2016 09:30 am
Quote
New material, new engines, smaller wings than ever before (while still functioning as an airplane),
Wing loading for the MD MD11F was 844 Kg/m^2. That was for a passenger carrying airliner. I don't have  a figure for wing area for Skylon but anything above 386 m^2 would put it's wing loading below that.

With a length of 82 meters, and the design on wikipedia remotely to scale, it's considerably less, indeed. That's the point of a SSTO. Smaller wings, less mass to haul along. Which means a higher cruising speed to compensate for the smaller wings.

I don't think comparing wing loading calculated makes much sense when comparing skylon against traditional airliners; On Skylon, most of the lift comes from the body, not from the wings. So the "effective wing loading" of Skylon may be less than half of the "calculated wing loading" of Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 08/02/2016 10:02 am
And that's the sort of exaggeration that makes everything else you say suspect.
And that's the sort of pointless comment that makes people suspect you have another agenda.
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There's no analogous relationship between the Skylon design and the two round-nosed, stubby-body, delta-wing orbiters (STS/Buran), nor with the tiny little X-37 spaceplane.
I'll spell it out for you. There are 2 proven full size (for their task) configurations which have been shown to survive return from orbit. Stubby, dense capsules and wing/fuselage designs. If Dream Chaser flies we can add lifting body as well.

Of these Shuttle was the closest to a full stage, with main engines and payload.  We know such a structure can be built and work.  That's the "known" part of the equation.
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Skylon is an entirely new untried dissimilar design.
I spent a whole post explaining my views on risk. But it seems you see what  you want to see.
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You can't just say "Oo, look, wings" and expect anyone to take you seriously.
Nor did I. But again you seem to see what you want to see.

I didn't bother to emphasize that Skylon is a fully reusable vehicle and is expected to go through a full test programme like an aircraft.  I thought it was redundant. Obviously an oversight on my part.
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(As Lars-J notes, it'd be like comparing a reusable upper-stage and a capsule, "Oo, look, wingless".
Which may explain why trying to land an upper stage has proved so difficult.
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There's just no comparison. And Lars could have also added a re-entry body for a warhead. Or even those three winged re-entry vehicles: They have as much similarity, from a physics standpoint, to a reusable upper-stage as they have to Skylon. (Ie, none.))
Again the specific point I was covering was re-entry. They all do (or did) it roughly horizontally. In fact they will have more similarity to such an upper stage as they all went up vertically and spent most of their re-entry moving horizontally.  I await the first upper stage ever to duplicate that feat with much interest.
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Firstly, if you are going to address a comment to me, address it to me. "Some people" is just passive aggressive nonsense.
It was only when I took a step back that it occurred to me that the fact I could hold what seemed opposite views about what seemed the same thing could seem strange.

You have a very high opinion of yourself if you think my post was only addressing you.
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Secondly, you couldn't have missed my point more if you'd deliberately got into a car and travelled in the opposite direction until you hit ocean.
Perhaps you should explain exactly what was your point? I got lost in amongst  the various quotes you included.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: john smith 19 on 08/02/2016 10:30 am
With a length of 82 meters, and the design on wikipedia remotely to scale, it's considerably less, indeed. That's the point of a SSTO. Smaller wings, less mass to haul along. Which means a higher cruising speed to compensate for the smaller wings.
Wing loading or wing area? Either way shifts  you comment
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That's what I said. The Skylon needs a dedicated runway to get to orbit. Using the SABRE engine for an airplane doesn't require the Skylon design.
There's what you seem to have meant and what  you wrote. The term you're looking for is "runway"
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Much like how most passenger luggage is shipped in fact.

Oh yeah, last time I took the airplane, the preloaded cargo bay was inserted into the plane. Totally forgot about that one. And after that, the passenger cabin was attached to the wings that had just landed. No reason to wait to board until the previous passengers had gotten off.
I doubt you've ever paid any attention to how aircraft passenger luggage is shipped. It mostly uses these things.

https://en.wikipedia.org/wiki/Unit_load_device

So yes actually most passenger luggage is shipped in pre loaded units, which is how I was careful to phrase it.
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Wait, that design also exists only on the drawing board. (I've tried finding the thread, but no such luck. Apparently, I didn't post in it).
And the aircraft involved has even been named on this thread, which makes your inability to find it even worse....
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Curious statement, coming from the man who's arguing that there's nothing that revolutionary about the Skylon. Personally, I think it has quite a few new features, that'll require a lot of funding to get the kinks out. It's high risk, with possible high gain (as you said yourself, very confusing compared to the post I quoted above).
Then perhaps you should try reading this post, which explains my views.
[quote john smith 19 link=topic=36826.msg1565303#msg1565303 date=1470074522]
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Will it fly? Who knows. Personally, I'm not going into that one until there's a full scale model of the SABRE engine. Otherwise, there's nothing but opinion to argue with.
We will look forward to hearing from you then.
Title: Re: The Reaction Engines Skylon Master Thread (5)
Post by: Chris Bergin on 08/02/2016 07:28 pm
This thread is cooked, well done. But unlike a tasty steak, it's burnt.....where am I going with this. Oh yeah, locked, new thread time! ;D

Oh and bloody behave. Too many people waving their arms around and being all rowdy.

Thread 6:
https://forum.nasaspaceflight.com/index.php?topic=40846.0