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)
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").
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.
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 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.
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.
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.
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?
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.
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.
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.
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.
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.
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.
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.
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.
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.
economic viability of the complete system, including engines and airframe.
economic viability of the complete system, including engines and airframe.
that was done by others, not by rel... eg. esa, london economics, etc
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.
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?
I don't see them claiming that their plan is set in stone.
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 systemWhich would in fact have doubled the development budget as they would had to look at 2 vehicles
and the testing around hypersonic separation.
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?
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?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.
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.
(Not to mention a hypersonic passenger plane.)Then why mention it? It's a separate project that was sponsored by the EU.
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. :)
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."
But you dare suggest they are being a bit premature...Perhaps because the launch problem isn't like your rather elaborate metaphor?
{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.
You clearly know his mind better than we do. Perhaps you could explain his thinking?Quoteand 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?
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?Yet another new forum visitor. You really are coming out of the woodwork today. :) Welcome.
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.
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.
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.
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.
Yet another new forum visitor. You really are coming out of the woodwork today. :) Welcome.Thanks. :)
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.You're operating under a very big misunderstanding.
The only reason it goes above the atmosphere is to avoid the trouble with staging at hypersonic velocities while in the thick atmosphere.
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.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.
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.
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.I'll quote what Hempsell, who was with REL at the time, had to say.
So, while the deployment window is short, I believe it is manageable.
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?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.Quote
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.
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.
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. :(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.
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.
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.
There'd be no shame in their saying "we don't know yet".
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.
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.
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.
In other words SpaceX was "unproven" until they actually flew something successfully. (That would be the F9 btw :) )
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.
4) SpaceX have built a very fine ELV
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.
And REL have built a heat exchanger.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.
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...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.Quote5) 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?"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?
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.
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."
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
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.
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. ???
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.
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.
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?
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.
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 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.
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.
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.
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.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.
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
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.)
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.
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?
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 :)
Denigrating the hard work by done by people trying for the same goal but by different means.
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.
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.
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?
QuoteSpaceX 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.
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.
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.
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 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.
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?
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.
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.
The two biggest hurdles technology wise were the heat exchanger and the rocket motor both of which have been demonstrated.
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".
Is it perhaps that BOTH sides are missing the point that the discussion comes from "good intentions" on both sides?
QuoteBlind 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? :)
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?
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
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?
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 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.
Indeed. It's one of those ideas that sounds very sensible, until you look at it a bit more closely.
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.
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.
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.
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.
Also on the 26th of March he's a speaker at this event:
http://www.develop3dlive.com/speakers/
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?
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
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?Indeed. It's one of those ideas that sounds very sensible, until you look at it a bit more closely.
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.
QuoteI 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.
QuoteMany 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.
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
The X-33 wasn't VentureStar, VentureStar was a powerpoint, X-33 was an active x-plane project
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.
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?
Do I then assume that you deride the various "Fully-reusable TSTO is a done deal" SpaceX fans the same way?
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.
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.
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?
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.
about wooing investors with the promise of making high-speed turbojet engines more efficient and effective. why would they?
Paul451, I understand you haven't really been around
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.
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 opinionThen you'll be pleased to know that SpaceX have been doing plenty of 'real man's engineering' :)
make it a science because science is the creation and testing of theories, engineering is the creation and testing of devices.
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.
I thought their money is from a 60 million pound government investment [...] Why are you leaving out the major sources?
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 fewerdollarspoundseuros.
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.
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.
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.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".
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.
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.
"Step 1: Get £10 billion investment..."
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.
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.
Science is creating the rocket-equation
Do we think we know enough about SABRE to state categorically that it only works when integrated with a Skylon type of airframe?
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.
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. :)
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.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. :(
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.
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.
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. :(
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.
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?
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")
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-spaceWelcome to the forum and the thread.
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
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?
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.
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
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.
2) deliver the specifically designed lander into space, and bring the squad there when it is needed.
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.
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-spaceWelcome to the forum and the thread.
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
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.
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.
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:Thank you.
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.
-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.Given the advances in supersonic and hypersonic flow heating analysis is the "needle nose" even plausible today?
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.
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. :(
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
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?
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...]
@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.
@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" :)But only a small bit :(
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?
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.
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.
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.
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).
My impression was a single full-size SABRE with wings and tank
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 tankIf 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 was a single full-size SABRE with wings and tankIf 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.It's a swings and roundabouts problem. :(
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.
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?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.
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 ...
what existing aircraft uses lh2?
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...
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. :(
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#msg1298468Quote from: SICA DesignPhases 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).
:QuoteMy impression was a single full-size SABRE with wings and tank
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: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.
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.
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
Build a heat-shielded jet aircraft lighter than 15 tons or maintain a network of LH2-capable runways in hostile regions, neither seems particularly feasibleCorrect.
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.
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.
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.
Build a heat-shielded jet aircraft lighter than 15 tons or maintain a network of LH2-capable runways in hostile regions, neither seems particularly feasibleCorrect.
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 workWelcome to the forum.
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.Welcome to the forum.
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.
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.
UK ministers issue spaceport shortlist:-I don't think any of the runways have the necessary 5000m for a full Skylon runway.
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.
UK ministers issue spaceport shortlist:-I don't think any of the runways have the necessary 5000m for a full Skylon runway.
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.
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.
Build a heat-shielded jet aircraft lighter than 15 tons or maintain a network of LH2-capable runways in hostile regions, neither seems particularly feasibleCorrect.
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. :(
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.
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.Welcome to the forum.
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.
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. :(
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.
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
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.
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...
DROP TROOPERS! :)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.
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.
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 :) )I also think it's pretty clear that whatever such a vehicle would be it's definitely not a Skylon anymore.
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...
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.
Approx. 97% off-topic:
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.
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
QuoteThe 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 ??!!
QuoteThe 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
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.Interesting analogy.
http://forum.nasaspaceflight.com/index.php?topic=24621.msg735577#msg735577Quote from: HempsellWe 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.
JS19, your argument about 'bulk cargo' makes a lot of sense.Welcome to the site.
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 ?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.
Skylon kills this business case by providing cheap access. it brings the value of water down from 14k $ per kilo, to 600 $ per kilo.
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).No, it means he wants to focus on the technology development.
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?
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.
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.In theory yes, in practice no. :(
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.
I used to think RR might take REL over at some point, but now I just wonder why they haven't already.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.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. ..... :-)
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.
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.
....
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"
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.Then you'd be talking about REL's work on the EU funded LAPCAT project for M5 airliners.
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.
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?
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.Then you'd be talking about REL's work on the EU funded LAPCAT project for M5 airliners.
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.
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.
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.
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.
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. :(
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?
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?This looks interesting but I missed it.
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.
Develop3D Yep, all the videos from #D3DLive will be posted online soon. Stay tuned for the release announcement in the coming weeks
Re Richard Varville's talk at Develop3D. I asked them on their Facebook page about the video and they answered:I'll have to look out for that.QuoteDevelop3D Yep, all the videos from #D3DLive will be posted online soon. Stay tuned for the release announcement in the coming weeks
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?This looks interesting but I missed it.
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.
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 :(Not a problem. We'll wait for the videos.
It was a good talk, nothing that seemed a new revelation, but then I haven't been following the technical development too closely.It's the current status part that's likely to change over time.
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.
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
Re the need to cool the canards:REL probably chose water cooling over something like heat pipes because the system has been flight tested at least once.
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?
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.
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.
Below are some thoughts on Skylon areodynamics, and safety. I could be making some incorrect assumptions here, so am happy to hear corrections.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?
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.
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. :)
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.
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.
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. :(
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>
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.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.
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.REL state the landing speed and sink rate is such that it could land on grass. Note landing, not take off.
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.
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.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?
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.
For a VTOL SSTO, rather less so for an air breathing HTOL. This matter has been discussed before.
Assessments of Skylon tend to focus on it having 'near impossible' SSTO performance,
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.
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.
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.
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.
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. :-)"
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.
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."
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.
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. :-)"
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.QuoteThen 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.
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."
"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?"
Rather than repeat myself here, I'll refer interested parties (if there are any) back to my initial post on thisI 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.
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.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.
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.
"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. :(
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.
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.
Lots more jobs appearing on the Reaction Engines websiteYes 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.
http://www.reactionengines.co.uk/careers.html (http://www.reactionengines.co.uk/careers.html)
nice! are these new jobs or sobstitutions of people that left?A lot of those roles look new.
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"........
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.
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
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
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.
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
"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."
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.
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.
"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."
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.
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.
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?
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 :)
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?
Many of us has argued that from the start.And you didn't email REL to share your profound wisdom with them?
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.
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.
- If the upper stage has a propellant mass fraction of 0.9 staging at Mach 15 gives me ~2.5x the payload (Skylon C1).
Richard Varvill's talk has now been uploaded at:
https://player.vimeo.com/video/124910371
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.
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...
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!!
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.
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...
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
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?
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.
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. :(
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...
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.
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.
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.
Honestly, the press release makes my previous gut feel that much stronger - it's Scimitar the USAF really want.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.
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.
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...The cargo transport contract to the ISS is about $18Bn
I am slightly concerned about IP having been already handed over in this CRADA process however...
$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.
Ok. But I am sure the USAF can use their imagination :)Honestly, the press release makes my previous gut feel that much stronger - it's Scimitar the USAF really want.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.
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.
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...The cargo transport contract to the ISS is about $18Bn
I am slightly concerned about IP having been already handed over in this CRADA process however...
$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. :(
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.
Honestly, the press release makes my previous gut feel that much stronger - it's Scimitar the USAF really want.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.
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.
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...The cargo transport contract to the ISS is about $18Bn
I am slightly concerned about IP having been already handed over in this CRADA process however...
$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. :(
...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.With the Delta IV and Centaur the USAF have demonstrated they will tolerate LH2 for certain specific tasks, primarily launch.
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 :)
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?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?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.
With the Delta IV and Centaur the USAF have demonstrated they will tolerate LH2 for certain specific tasks, primarily launch.
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.
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.
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".It might seem like a reasonable comparison but it's not really a fair one.
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?
Could SABRE potentially work with methalox?...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.With the Delta IV and Centaur the USAF have demonstrated they will tolerate LH2 for certain specific tasks, primarily launch.
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 :)
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?
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 :(
The SABRE development programme is roughly $300m, I'd guess that's peanuts relative to the inflation adjusted costs of the SSME.
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.
QuotePossibly, 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.
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.
JS19That's very flattering. I'll try to continue to live up to your expectations. :)
**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.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.
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
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. :)
**I think the Scottish government would be happy to welcome REL to the country.**No. It will be made in Culham.
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.
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.
That's $360M to get to first working prototype.
He is also Boris Johnsons's brother.
http://en.wikipedia.org/wiki/Jo_Johnson
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.
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.
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.
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?
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.
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.
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.
An aerospike could also be used to alleviate heating on the sharp fuselage nose as it will face similar heating issues.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.
(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.)
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.
...
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.
...
Its a pdf, does this work? https://www.aiaa.org/WorkArea/DownloadAsset.aspx?id=14414
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.For those interested in tank design John Whiteheads paper makes very interesting reading.
url?
Doubtful. That rule applies when the tanks of the LV are virtually all of the dry mass (which for ELV stages they often are)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.
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'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. ]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.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.
There are a number of new things that need to be developed. These includeDrawing from various REL presentations I'll mention when REL looked at a particular area.
1. The transitioning inletOngoing since 2012. Inlets with moving centre bodies have been around since the late 50's.
2. lox cooled chamber2010. Also the use of air cooling for the cooling while the vehicle is air breathing.
3. heat exchangers, both the primary one and the high temperature silicon carbide one.Under study since 2002.
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.
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.
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.
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? :)
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?
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)
Doubtful. That rule applies when the tanks of the LV are virtually all of the dry mass (which for ELV stages they often are)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.
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.
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.
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
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
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?
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.I think the usual expression in patenese is "to those skilled in the art." :)
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?
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.
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.
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...
:-[ 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.
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.
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.
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
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 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.In some ways the simplest motivation is that it can be done at all encourages people to try finding out how.
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.
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.Logically yes.
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.
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)
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?
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.
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.
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.
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 ...
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.
And raise a very significant amount of funding.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 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 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.
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.
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...Part of it is the way the European system differs from the US model.
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.
- PRESS RELEASE -
Monday 15 June 2015
Reaction Engines Ltd. have begun their latest round of rocket engine testing in Westcott, UK.
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.
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.Hempsell mentioned this on a Space Show, but I can't recall which episode.
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?
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?
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.
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.
@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...
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.
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...
My very dodgy guess at Skylon's T/w is 0.26.
... 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... :) )
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.
No, perhaps not the best word, but engine no longer shares a fuel delivery system, rocket chambers or preburner betweeen modes.... 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... :) )
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 :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.
the proposed work will include investigation of vehicle concepts based on a SABRE derived propulsion systemNow 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 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.
OneWeb satellite operator eyes huge rocket campaignhttp://www.bbc.com/news/science-environment-33268180
@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.
@t43562The trip to GEO is planned to use the Skylon Upper Stage. That's designed to carry about a 6500Kg payload to GTO.
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.
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.You might like to look at the 1st generation Orbcomm satellites.
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.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.
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?I don't think so. The dispenser is part of the payload. It's designed to fit on the front of the upper stage.
well, not sure of names, but it must have these characteristicsOriginally REL were only talking about the pre cooler but their skills seem to be growing and their confidence at executing the whole design.
I would bet on RR, Boeing or LM, but who knows?
well, not sure of names, but it must have these characteristicsOriginally REL were only talking about the pre cooler but their skills seem to be growing and their confidence at executing the whole design.
I would bet on RR, Boeing or LM, but who knows?
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?AFAIK LM make no commercial products. All they do is a)Government contract work b)National security systems c) Weapon systems.
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.
ok, so we can exclude LM from the picture. Who else should be dropped?
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.
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.
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.
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.
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. :(
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.
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.
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.
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:Agreed.
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.Reasonable.
Good luck with that.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.
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.
I read that the Altas V was developed for a US Airforce program.It was.
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.
https://twitter.com/patriciavmayes/status/620858977602154496Now that injection plate is intriguing.
https://twitter.com/patriciavmayes/status/620858977602154496Now that injection plate is intriguing.
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...)
update from REL website.Look like RE learnt something publicity.
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
Curious comment from the UK space conference;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.
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
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.
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 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.
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.
That's a bit of a chicken & egg problemQuote from: http://www.reactionengines.co.uk/lapcat.htmlThe 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.
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 ...
Hello all,Welcome.
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: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.
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.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.
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.
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.
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.
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.
It's hard to see how flying through the atmosphere for longer, in an SSTO, is going to make a space plane safer.
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.
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.
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.
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.
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?
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 $5k business class tickets.
there is another problem with a suborbital skylon- the pricing would be totally out of reach for everyone but the wealthiest. A LEO Skylon launch, in the best scenario possible, could lower the kg/price down to 350$. 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.
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.
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.
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 understand that the trip through Reagan at Washington DC is very fast.
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. :-)
Reaction Engines concept of a full-scale Sabre ground demonstrator.Where did this come from?
Clearly not a flight model engine yet, but massive progress if this proves successful in 2018/2019.
So many things wrong with that picture....I'd certainly say it look like it was made by a graphics artist, not an engineer.
For those of us that aren't subscribed to Aviation Weekly, does it say anything new or interesting in the article? Thanks.
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...
From the Aviation Week digital magazine. Photo credit Reaction EnginesThat's an interesting qualification.
I'm not the only one who thinks of LM as strictly a government contractor and nothing else.
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.
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.
I'm not the only one who thinks of LM as strictly a government contractor and nothing else.
Doesn't mean it is right.
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.That's an assertion.
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?
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
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.
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.
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.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.
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.You need to develop a bit more of a feel for engineering. :(
http://nextbigfuture.com/2015/07/nuclear-thermal-turbo-rocket-with.html
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
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.
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.
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.
"The question to answer next is what benefit the Sabre could bring to high-speed aerospace vehicles compared to other propulsion systems,”(Hellman, AFRL)
“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.”
“very risky as a first application,”(Hellman, AFRL)
“Sabre may provide some unique advantages in more manageable two-stage-to-orbit configurations.”
“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)
“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.”
“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)
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 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).
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. :(
Skylon is: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.Quote“very risky as a first application,”(Hellman, AFRL)
“Sabre may provide some unique advantages in more manageable two-stage-to-orbit configurations.”
(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)
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.
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.
Sam HutchisonIt 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.
**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?
Could you explain perhaps exactly how you see SABRE 4 and Scimitar as very different internally? To my eyes SABRE 4 seems Scimitar inspired.Skylon is: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.Quote“very risky as a first application,”(Hellman, AFRL)
“Sabre may provide some unique advantages in more manageable two-stage-to-orbit configurations.”
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. :(
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.
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 $$$$ that could help further the Skylon project).
I'm confident you're reading too much into this. It would be a different matter if Alan Bond said "we're switching to TSTO" publicly, but here you have their Director of Corporate Development sound just exactly like someone in that role should: he's being broadly supportive of the AFRL statement - i.e. their recent partner who they may hope to work with again (read $$$$ 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.
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.
At least certainly not in the timeframe as currently envisioned by REL.
Star OneWorrying 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.
**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.
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.
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.
Maybe the AFRL have in mind a hypersonic aircraft sporting heat exchangers, carrying a scramjet vehicle to start up speed.
Maybe the AFRL have in mind a hypersonic aircraft sporting heat exchangers, carrying a scramjet vehicle to start up speed.
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).
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?
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?
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.
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. :(
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. :(
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).They are but this needs LH2 and armed forces are very wary of cryogenics.
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).
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.
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.
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+.
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.
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.QuoteLooking 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).They are but this needs LH2 and armed forces are very wary of cryogenics.
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).
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.QuoteI 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.QuoteMach 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.
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.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.
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. :(
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 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?
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?
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. :(
Came across this recent NASA Ames conference paper on Skylon that I thought might be of interest to followers of this thread.Interesting report.
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]
This looks slightly alarming at Mach 12: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.
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?
NASA's analysis is that REL figures for lift and drag are conservative and underestimate how good the design is.
This looks slightly alarming at Mach 12: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.
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?
The use of altitude compensating Expansion/Deflection nozzles should help also.
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!
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.
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.
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.
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.
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.
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.
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?
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.
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.
Not my assessment but the report's.QuoteThis 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.
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.
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. :(
I'd look a bit closer at those pictures.
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?
My suggestion was to move to a single large area ratio nozzleJudging by the diagram you supplied that's what already happens.
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.
My second suggestion is to crank the delta wing to increase the wingspan,Which gets what?
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.
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.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. :(QuoteI'd look a bit closer at those pictures.
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 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?
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.My suggestion was to move to a single large area ratio nozzleJudging by the diagram you supplied that's what already happens.
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.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.
It moves the nacelles further away from the fuselage trading wing mass for active cooling mass.My second suggestion is to crank the delta wing to increase the wingspan,Which gets what?
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.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.
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
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.
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.
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.
It's patented. REL would have to license it.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 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.
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.
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.
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 NASPWhich one? The original NASP of the early 60's or the later X30 of the late 80's?
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.
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.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.
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.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.QuoteNope, 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.
It's patented. REL would have to license it.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 might also be an idea to angle the nacelles a bit like in the Cfastt-1 design.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.
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.It's still a 2 phase mixture and this is a design approach REL seem very keen to avoid.
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.
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.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.
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.
For the x-30. I distinctly recall it from the book.Which one? The original NASP of the early 60's or the later X30 of the late 80's?
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
Where LH2 with either SH2 or mixed with something like Methane I doubt anyone has long term experience on any kind of industrial scale.
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.
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.
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?
... 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.
... 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.
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 estimateCurrent plans call for dumping the water just after take off as successful take off implies it's no longer necessary.
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 ... ???
@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.
Ok, so if we're posting numbers now I might as well post mine.That's about 2/3 of my worst case area estimate.
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.Another data point may put this number in perspective.
@RonMPerhaps not as far as you think.
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.
... 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.... 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.
@RonMPerhaps not as far as you think.
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.
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.
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.
You have more absolute faith in Skylon specifications that REL engineers themselves do.Again not in the sense you seem to mean. :(
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?
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.
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. :)
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 problem they're trying to solve is not the fundamental economic viability of the vehicle.
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.
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.
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?
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).
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.
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 ]
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.Depends what you mean by "quantum."
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
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.
And yet that "fudge" is exactly how every other transport system on this planet does business. :(
Historically people seem to have been thinking that you can gradually evolve to full reusability but SX have demonstrated that does not work.
The real issue would probably be that under US ITAR laws flying down to the Equator would be viewed as "exporting" the payload
Could it reach Hawaii from the US west coast?
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.
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.
The test programme is ~400 flights with just two vehicles, including a couple dozen abort tests.
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.
Will it be dramatically cheaper? Nah.Based on what?
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?
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: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.
"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'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...
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.
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.
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?QuoteWill 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 rateI didn't write about price. I wrote about cost. And I explicitly stated that.
I had this image of some rockets...
Over in an L2 SpaceX thread, Ronpur50 put together a simple size comparison of some extant launchers with some speculation on the SpaceX BFR:It's big.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.
OK, I'll try to explain it one more time...I agree if the system is to operate without any government subsidies.
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.You still persist in thinking this is a government programme. If the costs are not fully recovered the business is insolvent and closes.
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.
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.
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" ?
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.
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.
Now, what would be the operating costs, and how many times could it be reused?
I agree if the system is to operate without any government subsidies.What have government subsidies to do with all this?
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.
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.
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.
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?
...
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.
{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.
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?
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.
Or, you can buy your independent space access system with minimum of 200 launches ready developed for significantly less.
Depends on who builds the fuselage and what the payload is (and who built that), doesn't it?
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.
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.
...
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.
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.
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
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.
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?
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.
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.
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
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)
Full reusability makes Skylon an asset not an expense (and in effect a lottery ticket) as current ELV's are.
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.
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.
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.
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.
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.
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
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.
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.
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.
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.
of course it's an asset. Only a foolish would think otherwise.
No, a country could set the price at pretty much anything they want.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.
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.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.
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?
Well, we'll see. There was another RLV that was supposed to reach that price range....And your point....
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.
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.
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.
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.
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.And yet some how China, India and (IIRC) Indonesia do maintain large fleets of large aircraft.
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.
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.
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.
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.
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.
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?
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?
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.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.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.
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?
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 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.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.
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).
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.
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.
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.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.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.
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.
Another interesting hire:Quote from: http://www.reactionengines.co.uk/news_updates.htmlJonathan 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.
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.It's a fair question. I'd like to see a few more companies other than RR show themselves
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.
not exactly skylon news but....Closer than you might realize.
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
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.)Dig a little deeper.
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.
guys, I think I need few clarifications as I am no engineer.The focus is the DLR "MR2" design, which is their M8 plan.
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)?
I wonder what this is all about?About 55 years too late.
http://aviationweek.com/technology/turbine-engine-could-pave-way-supersonic-cruise-missiles
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.
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/
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.The IAC update seems to have happened but I can't find any crumbs of news or comments about it:" The vehicle can
https://iafastro.directory/iac/paper/id/31601/summary/
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?
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.
...
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?
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.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.The IAC update seems to have happened but I can't find any crumbs of news or comments about it:" The vehicle can
https://iafastro.directory/iac/paper/id/31601/summary/
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?
...
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 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.I'd be surprised at that.
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?
On page 3 of the report it says: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.
**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?
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.The IAC update seems to have happened but I can't find any crumbs of news or comments about it:" The vehicle can
https://iafastro.directory/iac/paper/id/31601/summary/
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?
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.
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 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 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).
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.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.The IAC update seems to have happened but I can't find any crumbs of news or comments about it:" The vehicle can
https://iafastro.directory/iac/paper/id/31601/summary/
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?
do you expect substantial costs reduction from getting rid of frost control?Probably not much.
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.
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.
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.
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.
There is the benefit that you've lost a fourth liquid system from the engine which operationally must mean lower maintenance costs.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.
AFRL is also looking at vehicle concepts.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).
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.
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.
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.
"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. "
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?
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.Not nearly well enough to convincingly answer the question.
I might be wrong - how in-depth were your calculations?
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.
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.
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.Anything is possible but this sounds more like one of those "cover all the bases" clauses that patent drafters like to use.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.
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. "
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.
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).
{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.
Could nitrogen be used instead of helium at those temperatures?
The liquid hydrogen heat exchanger cools the helium down to 50k so if it was nitrogen it would freeze.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.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.
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 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.
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.
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.
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.
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.
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.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.
Noted but the standard only has 1 design win with only 1 test flight of hours.
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.
What's the main point of using ethernet though? Is it to reduce the number of cables or to increase the data rate?
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.
{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 ]
Provided it uses Spacewire, which I think is likely.{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.
{snip}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.
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.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.
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.
BAE buys 20% stake in Reaction EnginesWell that must be the bargain of the century.
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".
- 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.
How far back are they scaling the test engine work though? That might hurt more than the funding help...
The refrigeration technology may permit spinoffs. I wonder if there are any none aerospace applications that need rapid cooling to cryogenic temperatures?
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 :)
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.
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.
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 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.
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.- 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.
Except it's not more funding than they've ever had before.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.
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.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.
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?
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
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.QuoteThe 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
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?
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.
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.
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.- 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.
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.
BAE buys 20% stake in Reaction EnginesThe synopsis is much appreciated.
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:
That does not sound like much for something that REL have significantly de risked over the last few decades.
- 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.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.
- 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?
- 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 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.
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.
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.
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?
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.
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'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 ;).
If SpaceX can increase the demand for spaceflight by lowering costs with reusability, that only improves Skylon's chances of being developed.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.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.
Not if in the process SpaceX's costs go below those projected for Skylon.
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.
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.
There's no reason to actually think Skylon would have better reliability.
historically liquid hydrogen systems haven't been as reliable as systems using other sorts of fuel.
Ummm... Development costs are sunk costs and so have no impact whatsoever on the operational economics.
Concord had excessive operating costs (it was still lossy after they wrote down all of the purchase costs)
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 it can wait out bad weather on orbit or divert to almost anywhere in the world (the wings afford a very large cross range),
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.
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 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.
Quotehistorically 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.
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.
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 .
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?
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.
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.
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.
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.
It lands like an airplane (well, like a glider), which is a comfortable, well-understood maneuver (particularly for a computer)
Quotehistorically 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.
...
Dragon can also wait out bad weather on orbit. It doesn't need much cross-range capability to do that.
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.
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.
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.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.
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.
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.
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?
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.
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
So, I was watching this interview on CNN and the image below popped up. What is this?Interesting but a bit disturbing.
http://www.cnn.com/videos/business/2015/11/04/bae-systems-reaction-engines-mark-thomas-intv-qmb.cnn
So, I was watching this interview on CNN and the image below popped up. What is this?Interesting but a bit disturbing.
http://www.cnn.com/videos/business/2015/11/04/bae-systems-reaction-engines-mark-thomas-intv-qmb.cnn
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?
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.So, I was watching this interview on CNN and the image below popped up. What is this?Interesting but a bit disturbing.
http://www.cnn.com/videos/business/2015/11/04/bae-systems-reaction-engines-mark-thomas-intv-qmb.cnn
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.
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?
So, I was watching this interview on CNN and the image below popped up. What is this?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.
http://www.cnn.com/videos/business/2015/11/04/bae-systems-reaction-engines-mark-thomas-intv-qmb.cnn
So, I was watching this interview on CNN and the image below popped up. What is this?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.
http://www.cnn.com/videos/business/2015/11/04/bae-systems-reaction-engines-mark-thomas-intv-qmb.cnn
The question is can REL turn this increase exposure into either increased funding or move them forward in forming the Skylon consortium?
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".
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.”
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.”
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.
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.
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.
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.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.I hope not.
Wonder if the demonstrator will be manned or a drone?
That looks like a study of reentry aerodynamics at high angle of attack, not the low angle of attack on the way up.So, I was watching this interview on CNN and the image below popped up. What is this?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.
http://www.cnn.com/videos/business/2015/11/04/bae-systems-reaction-engines-mark-thomas-intv-qmb.cnn
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
I increasingly see the parallels with the Taranis technological demonstrator. As that is to drone technology so this will be to hypersonic research.I hope not.
Wonder if the demonstrator will be manned or a drone?
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. :(
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.
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.
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
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.
If Skylon loses propulsion
Also, propulsive landings give more than one shot at an approach.
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!
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.
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.
STS killed more astronauts than any other space launch system in history.
STS's problems came from trying to push the edge of what is possible -- exactly what Skylon hopes to do.
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.
STS had one catastrophic engine failure -- of a solid engine.
No, they affect costs. Development costs are costs.Ummm... Development costs are sunk costs and so have no impact whatsoever on the operational economics.They affect launch prices (not 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.
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.
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.
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.
Quotehistorically 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.
I agree that advocates are grossly underplaying Skylon's complexity and risks
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.
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.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.
Even better/cheaper build a subscale version using existing rocket engines. These don't necessary need to be hydrogen fuelled engines either.
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?
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.
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.
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.
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.
Allan Broad said it would cost £350 to get finished engine. £10B to produce Skylon and engines, I think this is large scale manufacturing.
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.
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.
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?
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?
“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.”
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.”
“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."
Orbital reentry of razor-thin tank airframe is something with "razor-thin margins".Welcome to the forum.
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.
Your memory seems to be failing. Let me refresh it.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.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."
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.
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.
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.
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.
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.
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).
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.
https://www.flightglobal.com/news/articles/analysis-british-spaceplane-engine-concept-gets-cas-418612/?cmpid=NLC|FGFG|FGFIN-2015-1117-GLOB&sfid=70120000000taAhIt 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.
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 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.
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.
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.
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.
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,
The engine will probably be used in a subscale technology demonstrator.
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,
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.
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?"
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?"
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.I think so too.
http://www.reactionengines.co.uk/press_release/Press_Release_17July2013_SABRE.pdf
http://www.bbc.com/news/science-environment-23332592
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.
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.I think so too.
http://www.reactionengines.co.uk/press_release/Press_Release_17July2013_SABRE.pdf
http://www.bbc.com/news/science-environment-23332592
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.
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.
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.
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.
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.
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.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.
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.
AFAIK this solely applies to communications satellites and parts. Launch vehicles remain dual use with all the problems that implies.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).
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/
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.Quoteif 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.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.
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.AFAIK this solely applies to communications satellites and parts. Launch vehicles remain dual use with all the problems that implies.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).
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'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.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.
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.
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.
When, if ever, will Skylon fly? Anyone want to put down a prediction?1st flight.
I meant an actual year.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.
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"?
Anyone have a year?
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.Anyone have a year?
Why?
What a good idea.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.Anyone have a year?
Why?
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.
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.
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.
Incidently you're confusing SSTO with reusability.
And to be fair you should mention that Falcon Stage 2 reusability is harder because it typically returns from geostationary transfer orbit.
it's darned difficult to find applications for Skylon that are uniquely compelling other than satellite launch.
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.Anyone have a year?
Why?
Basically that was the theft of a Russian satellite.
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.Which could be said of all launch vehicles.
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.
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?
"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. :(
Most of what was uniquely useful about STS is also possible with Skylon, which is almost certain to be vastly cheaper.
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.
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?
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.What a good idea.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.Anyone have a year?
Why?
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."
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.
Such a consortium would need to be truly multinational - so no one put RAF roundels on the wings ;).
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.
Now that semi-reuse has been demonstrated
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.
Concorde, the Channel Tunnel
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.
QuoteConcorde, 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 !
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
On which data do you assume there such a high market for suborbital flights and there is not for orbital ones?
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.
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.
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).
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).
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.
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.
Travelling 18 000 km using P2P would take as much energy as Earth escape, or beyond.
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).
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.
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?QuoteI'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?
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?
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...
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.
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.
Yes. Russia, the USA, and a few other countries already have several thousand of these.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?
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.
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
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
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.You need to keep in mind a couple of things about this scenario.
Yes. Russia, the USA, and a few other countries already have several thousand of these.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?
The ICBM killed off the strategic nuclear bomber 50 years ago. Skylon won't bring it back.
“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.
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
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.
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.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.
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?
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.
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
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.
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.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
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
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
60 million pounds ($.4 million USD)
up to 20 times the speed of sound if it's going into orbit
high-vacuum braise
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
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
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.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?
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.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. ...
Did the UK just develop a serious inflation problem?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-idUSKBN0TJ19U20151130Quote60 million pounds ($.4 million USD)...
...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
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.
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.I always thought the frost control that Sabre had allowed it to achieve an air breathing performance no one else could match.
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. ::)
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.
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.I always thought the frost control that Sabre had allowed it to achieve an air breathing performance no one else could match.
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. ::)
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.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.I always thought the frost control that Sabre had allowed it to achieve an air breathing performance no one else could match.
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. ::)
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.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.I always thought the frost control that Sabre had allowed it to achieve an air breathing performance no one else could match.
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. ::)
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.
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.
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.It will be named "Gorm".
Dauntless
...or
Indomitable
But I am sure you can do better.
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.
And likely will never.And that's where you start making assumptions.
Not a given. There is no proof that it will happen. Skylon likely will be too complex to be operated manyNow that sentence definitely needs an object at the end of it. It's basically impossible to answer without one.
The Skylon concept presents a freight company model, but the manual makes mention of Launch control, Facilities, Range Safety and Mission ControlKeep in mind it is a UAV.
Does anyone have a feel for how these would be sized in relation to those needed for current launch vehicles?
The Skylon concept presents a freight company model, but the manual makes mention of Launch control, Facilities, Range Safety and Mission ControlTo 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.
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.
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.
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.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.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. ...
...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).
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.Now we get onto the important subject. ;D
Dauntless
...or
Indomitable
But I am sure you can do better.
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.Now we get onto the important subject. ;D
Dauntless
...or
Indomitable
But I am sure you can do better.
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.
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.
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.
While I might expect to have such facilities I doubt they would be on the scale of any a conventional launch system.
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?
REL's achievement lies in designing a thermodynamically more efficient engine cycle
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?
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.
Did I say they had built one?REL's achievement lies in designing a thermodynamically more efficient engine cycle
What "achievement"? They yet to build one much operate one.
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.
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.
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.
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..
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..
they plan a 200 flights test programme.
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
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.
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.
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.
He means REL selling launches after the 400 flight test programme (on 2 vehicles).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.
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.
So look at Spacex pad but without the erector.The word you're looking for is "runway." :)
I mean selling launches /before/ all orbital launches have been completed.IE for a piloted, 2 stage passenger carrying vehicle programme where there is only 1 test vehicle in the programme.
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.What specifically are you talking about?
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).
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. :(
And I see you ignored the "and other reusable test-bed vehicles."I mean selling launches /before/ all orbital launches have been completed.IE for a piloted, 2 stage passenger carrying vehicle programme where there is only 1 test vehicle in the programme....
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 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?
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.
Just 2 years of flight testing for 400 flights is VERY optimistic, as we can see from SpaceShipTwo and other reusable test-bed vehicles.
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.
I thought the 400 flights info comes from before they planned the boilerplate prototype?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.)
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.
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." :)
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.
I thought the 400 flights info comes from before they planned the boilerplate prototype?
The qualification flight test programme has two production prototypes (there are also two earlier full scale development vehicles which are probably not orbital).
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?
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.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
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?
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.
I don't understand how your reference to a VTOL would help me to understand your answer -
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.
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.
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.
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?
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)
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 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?
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?
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.
It uses LH2, which boils off quickly. They have only talked about the flight vehicle and not the ground support equipment.
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.
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.
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.
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.
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.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.
"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.
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'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
Subcooling doesn't prevent boil offBut 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.
1. It goes into orbit, that negates the aircraft designation. It is a launch vehicle.Skylon operates under the UK CAA rules.
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? :)
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.
b. ELV's use clamp bands and still some have CLA issuesI used CLA issues as an indication that REL are aware of all of the issue around payload integration between payloads and LV's.
c. It is more about the spacecraft structural stiffnessI'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.
d.. A bolted interface was not the driver of shuttle CLA issuesTrue. But I would ask if CLA was as big a problem with Shuttle as it is with ELV's?
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.
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?
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.
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.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"
Umm... yes.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.
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.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.
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 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.
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 eliminatedTrue. 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.
They are a problem if one is trying to adopt a airline-like operational model.
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.
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?
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?
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?
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.
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.
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.
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 LEO facility that straps them to a Fluyt to get them where they're going
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.
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.
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.
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.
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.Going back to an earlier post of yours.
Been around many spacecraft and containers.
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.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. 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.
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.
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.
1. It's the spacecraft with all the hyperbolasThat doesn't make sense. Can you explain it further?
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.
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.
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.
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.
1. It's the spacecraft with all the hyperbolasThat 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. 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.
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?
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).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
Uh, how far would it hobble Skylon operators to ban traditional toxic hypergols in payloads?
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).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 the very long term, with arbitrarily high reuse, then fuel cost matters. But we're not anywhere there, yet.
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?
It's about development costs, without computing SpaceX development costs.
sure, guess who wins? :)
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.
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...
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.
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.
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.
Well, this is where all the nonsense about the supposed advantages of separating operator and manufacturer business cases starts to hit you back...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?
This is not including development costs but costs of one LV.
Well, this is where all the nonsense about the supposed advantages of separating operator and manufacturer business cases starts to hit you back...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?
This is not including development costs but costs of one LV.
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
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.
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.
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.
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.
Also, when power is removed, all other modes have graceful degradation.You're extending assumptions and design decisions from one launch mode to another.
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.
And strategic weapon systems are definitely not being operated by their manufacturersBut 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"
Hypersonic strategic air-lift anyone?And possibly matter transmission and time travel as well. :)
https://www.flightglobal.com/news/articles/uk-predicts-more-stealthy-and-stand-off-ops-by-2035-420125/
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).
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.
But then they are delivered in orders of 100's,not ones and twosBingo. 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...
True, but over a period of 30 years.A flight rate is a flight rate, no matter how long you maintain it.
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.
assuming SpaceX is able to reduce costs down to 50% of F9Here, too, a static assumption makes little sense since this, too, will depend on the flight rate...
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.
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...
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.
Now that is true, although it could be said that the stable orbit part is the "cruise" state.
Advantage Skylon, I think, since it would be demonstrably more likely that you'd get your payload back if the launch failed.
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.
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.
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.
plus all those intact abort modes to a benign runway landing,
plus all those intact abort modes to a benign runway landing,
What says an intact abort is a benign runway landing?
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.
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.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.
There's an intriguing sentence here:Seen before. Already commented upon.
https://www.gov.uk/government/publications/future-operating-environment-2035QuoteThere 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.
:-)
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.
AFAIK there are no stats for damage to satellites on the Shuttle. It never happened.
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?
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).
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?
IIRC the 4 satellites of the Cluster mission that flew on the first Ariane 5 were re flown after recovery from the Guyianan jungle.
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.
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.
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.
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.
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.
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).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).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?
Well, so far he has done everything he claimed he would do... taking a bit longer than anticipated but he did it.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.
I re-checked the history and indeed they did build a new group launched on a pair of Soyuz.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.
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.
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.
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.
Upper stage reuse of the F9 (and FH) has also been abandoned.
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.
The "how does SpaceX compare to Skylon" discussion was relevant.You're confusing SpaceX (the company) with Skylon (the vehicle)
The "does Elon ever have to change plan" discussion is not (here).
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.
If you want a fair comparison Skylon first would have to fly.Definitely.
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. :)
you just have a vision. That's a difference.I think you're confused by what that word means.
9 engines recovered out of ten. 80% of dry mass recovered.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.
But "half".
Again semi reusable is not reusable. Fully reusable is reusable.Changing the definition of a word to have a more limited meaning borrows from another Silicon Valley company, Microsoft.
THIS THREAD IS NOT ABOUT SPACEx!
......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.
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....
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.You seem to have a very short memory.
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.
......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). ....
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....
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.......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). ....
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....
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.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.
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. :)
I'm sorry, I've been doing my best to follow this thread but I think I missed a turn there.......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)
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....
I'm sorry, I've been doing my best to follow this thread but I think I missed a turn there.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."
"...a few battleship pressure-fed rocket engine tests..."?
I hope this isn't out of turn but could somebody explain that last bit?
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?
Or a rocket powered Battleship! Lets face it that HAS to have some 'cool-is-the-rule' points :)Oh that's Niven and Pournell's "Footfall." :)
Randy
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!)
I think F9R's success so far, on balance, gives Skylon a better shot than it otherwise would.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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...Indeed the REL PR team is trying. I've sometime viewed their efforts and thought "this is very trying." :)
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 :) )True. Nice to see you posting again. It seems like it's been an age. :)
Randy
He's clearly part of the price for the BAe investment.Quote from: http://www.reactionengines.co.uk/press_release/2015-12-28_Chris_Allam_Appointment_FINAL.pdfThe 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.So, some experience with developing new technologies?
[...]
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)
He's clearly part of the price for the BAe investment.Quote from: http://www.reactionengines.co.uk/press_release/2015-12-28_Chris_Allam_Appointment_FINAL.pdfThe 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.So, some experience with developing new technologies?
[...]
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)
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.This suggests they are quite deeply integrated into the programme
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.
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.
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.
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.
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.
That's reasonable but I'm very weary of why BAe wanted "preferred supplier" status on some systems, and what they are.
{snip}
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.
No citation of Skylon, but lot of worries in traditional EU space circles reported.
... 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?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.
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.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.
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.
And why on earth are we talking about landing Skylon on a carrier? Let's move on.Certainly
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."
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."You're right.
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/
2] apart from carrier landings, which only happen in Bond moviesAnd that's where your comprehension fails. :(
Despite the bizarre tangents, everyone seems to agree the pilotless aspect of Skylon is not a big deal.True.
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.
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
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.)
Floating runway...
An article about TISICS whose job it will be to make the titanium composite struts (thanks to Jamie Rowland for sending me this link).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.
http://www.geektime.com/2016/01/14/this-uk-startup-is-building-a-new-kind-of-space-age-metal/
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.
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.
I was thinking of the hairy black space balls that farmers come across from time to timeare 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.
No boil off means no burn 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.
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.
No boil off means no burn off.
No such thing with hydrogen. There is always boil off.
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.
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)
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 :)
QuoteI'll admit that line struck me as odd as well: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
"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
Quoteand 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.
QuoteSimply 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.
QuoteI 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.That is a very suspicious definition. :(
I thought it referred to hydrogen at it's triple-point of 14.01 KIndeed.
Jim pointed out that a layer of paint alone was sufficient to reduce LOX boil off to very low levels.
I thought it referred to hydrogen at it's triple-point of 14.01 KIndeed.
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?
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. :)
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.
"MY" main point was the question of why NOT vents? (Thanks for the calc's JCRM :) )Well there's the practical and the philosophical.
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.
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. :)
QuoteActually 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.
Quote"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)
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.
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.
12% seems to be stated a little too precise given the way it was estimated. No need, however for the LWT:
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".Quote from: http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/et.htmlLiquid Hydrogen Maximum 227,641 poundsor 12.74%
[...]
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
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,
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?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)
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.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.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?
Make 'er out of Titanium, then...
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.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.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?
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?Quite a lot.
http://nextbigfuture.com/2016/01/charles-bombardier-has-improved.htmlAnd this has any relevance to Skylon how?
to quote daffy duck when he is about to be in a lot of pain: "mother"
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. :(
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. :)http://nextbigfuture.com/2016/01/charles-bombardier-has-improved.htmlAnd this has any relevance to Skylon how?
to quote daffy duck when he is about to be in a lot of pain: "mother"
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?
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. :(
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.
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...
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.
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.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.
Nitrile rubber fuel bladder...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.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.
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?
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!
Skylon could not get into space without an atmosphere, it relies upon lifting flight and aerodynamics for control, almost up to MECO
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.
I used the NASA source as you're less likely to dismiss it as biased.
OrThe 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.
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*
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.
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)
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 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.
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)
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.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)QuoteI 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.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)QuoteI 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.
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.The subject is referred to as "Responsive space" by the USAF and they have organized several conferences on it. AFAIK the proceedings are online.
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.
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.
<lasers>
Indeed I was thinking more "in space" not lift off ;)
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...
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.
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: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.
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.
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.
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?
"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
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.
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.
"USAF set to unveail concept based on Skylon technology"
http://www.space.com/32115-skylon-space-plane-engines-air-force-vehicle.html?cmpid=514648
"The oxygen in the chilled air will become liquid in the process."
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.
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.
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???
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.
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.
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
Because a two stage system gives greater design margins.It's believed a TSTO design give greater 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.AFAIK no one has experience of designing a successful SSTO of any kind, so who are these "experienced" people?
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.
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?
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.
intellectually dishonest.
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.
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 theYou'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.
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'tFunny. I've seen plenty of semiconductor documentation marked "provisional."
bet on it. The user manual for a non-existent system is science fiction.
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.Or indeed anywhere. :(
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...
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.
...
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?
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.
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.
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.
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...
Not necessarily. Don't exactly know what you mean by "first LH2 engine", probably first LH2 staged combustion engine.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.
"The company plans to test the engines this year"
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.
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.
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.
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
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.
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 $/kg, and the optimistic figure says 600....
SpaceX president yesterday declared that first stage reusability would cut prices of max. 30%, meaning a per-kg cost of 2800$. still sure there is no business case for Skylon? even being very pessimistic, it approaches a cost of 1500/2000 $/kg, and the optimistic figure says 600....Skylon is so far away from flying that "current" reusable pricing will be irrelevant.
They have a massive amount of detailed design work to undertake before work can start on construction.
I seem to recall Reaction Engines stating engine testing would not start until late 2018/2019
They have a massive amount of detailed design work to undertake before work can start on construction.
I seem to recall Reaction Engines stating engine testing would not start until late 2018/2019
I think there's some confusion between engine-testing and engine-system testing :)
As I understood it they need to test the various components in a basic configuration (hence the "bread-board" type layout) in order to refine the overall design requirements and system functionality. It won't be an "engine" but the systems of the engine run as a unit to define the design of the actual engine.
Just to clarify my position on this.
Testing of various components will progress over the next couple of years and then a "non-flight" proof of concept engine will be tested. If the testing proves successful I think they will endeavour to bring an airframe manufacture on board. I still think a first flight will not happen until around 2028.
Skylon is a post Ariane 6 launcher. It just cannot operate in such a low launch per year environment.
I expect by the end of the next decade the number of launches per year will be at a totally different level with a responsibility of companies to keep space clear of "trash" . There will be all sorts of large structures in orbit from power generation beamed down to earth, manufacturing in zero gravity and more, all needing service and supply. this is Skylons home ground.
My personal view of course!.
SpaceX president yesterday declared that first stage reusability would cut prices of max. 30%, meaning a per-kg cost of 2800$. 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....
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.
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.
Actually there is no business "case" for Skylon because of the simple fact there is no Skylon...
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.
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.
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.Certainly possible. What's odd is why would you would still call it SABRE, given so much of the design would be thrown away?QuoteNot 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.
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.I'm guessing where your post starts and ends as you seem to be having trouble with quoting.
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.
the 2014 NISSIG presentation (http://forum.nasaspaceflight.com/index.php?topic=33648.msg1171426#msg1171426)
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.Not necessarily. Don't exactly know what you mean by "first LH2 engine", probably first LH2 staged combustion engine.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.
But if you look at the development effort you'll see that it had several years of delays and huge cost overruns in development.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.
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.
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.I'm guessing where your post starts and ends as you seem to be having trouble with quoting.
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.
You don't appear to be aware that component design and testing has been underway (funds permitting) since the late 90'sthe 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.
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...
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.
Quote2) 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.
QuoteDespite 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.
QuoteProbably 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. :(
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.
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?
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.
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.
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
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?
[...] 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?.
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.
#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.
...And unfortunately Sabre is not very scalable. Nor down (engine reasons) nor up (infrastructure reasons) except single engine possibility.
Payload margins is wasted opportunity and means lost income.
Payload margins is wasted opportunity and means lost income.Better margins means less 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.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?
proof of concept and tech demonstrator [...] but I suspect it wouldn't save much development.
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
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.
You have mentioned "single engine possibility" more than once now.True.
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.
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).
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.
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.
You have mentioned "single engine possibility" more than once now.True.
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.
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.
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.
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.
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.
Engineering margins.
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).
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. :(
QuoteEngineering margins.
Last I heard, the airframe was being designed to a safety factor of 1.5, the same as a commercial airliner.
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.
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
Yes, this SSTO and all others. They are more sensitive to mass increases than other LVs, especially first stages.
Figured where I went wrong, I was looking at its rocket phase (LoX/LH) thrust of 440lkbs not airbreathing thrust which is considerably less.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]
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.
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.
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.
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.)
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.
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.
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)
Belly doors, obviously. (Loading would be via an elevator-pit.)I had not thought of this. More or less SOP for bombers though.
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.
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.
...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.
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]
Please consider that in Europe there is no something like NASA or DARPA which will pay for tech demonstrators.
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.
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.
...
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.
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.
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.
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.
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.
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.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.
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.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.
True. I think SSTOs would have a much stronger case if we had space tugs.The biggest change in REL's development plans was the introduction of the Skylon Upper Stage, which is a reusable space tug
However, with electric propulsion now being available to raise satellite orbits...
True. I think SSTOs would have a much stronger case if we had space tugs.The biggest change in REL's development plans was the introduction of the Skylon Upper Stage, which is a reusable space tug
However, with electric propulsion now being available to raise satellite orbits...
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.
Historically it was REL's plan to just build the pre cooler for the enging.
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.
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.
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?
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.
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.
A near perfect description of the X30 programme.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.
I have problems to see how TSTO would simplify, make development cheaper, less risky and still competitive
https://imgur.com/a/F87pA
@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.
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.@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 :-)
That's the C2 manual, it isn't in the D1 manual, and was (if I recall correctly) disavowed by the REL team
*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. :)
- 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.
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.
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.
True. I think SSTOs would have a much stronger case if we had space tugs.The biggest change in REL's development plans was the introduction of the Skylon Upper Stage, which is a reusable space tug
However, with electric propulsion now being available to raise satellite orbits...
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
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.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.
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-optimized upper-stage.
Original reply was lost in space/time :)According to Mark Hempsell it's out.That's the C2 manual, it isn't in the D1 manual, and was (if I recall correctly) disavowed by the REL team
*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. :)
It is in fact but still informative. If REL "disavowed" it they may want to take it off their website :)
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.
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.
Original reply was lost in space/time :)Having both versions shows how the design has been revised, so while removing it would be for claity I sincerely hope they don't.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 :)
QuoteActually 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
QuoteTake 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.
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
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.
According to Mark Hempsell it's out.
http://forum.nasaspaceflight.com/index.php?topic=34964.msg1272415#msg1272415
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.
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.
REL put the engines where they did because they are engine designers and not actually airframe designers.
issues with exhaust impinging on the airframe (could be a big issue, as we saw way up-thread)
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 understood the preferred method was self ferry.
it's actually the opposite; The length is decreased with a smaller propellant load
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.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...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.
No reason to assume it would be expendedbut 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.
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
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.And yet national governments keep funding them. While the LV is tied to a 2000Km artillery range they probably always will. :(
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?
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.
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.
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.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.
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.
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.
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.
This is the issue. The problem with it is
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.
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."
{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
{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.
Mark said they were aiming for 10 year lifespan for Skylon and rapid reuse
To be clear the exact quote I'm referencing is :QuoteMark said they were aiming for 10 year lifespan for Skylon and rapid reuse
{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 :QuoteMark said they were aiming for 10 year lifespan for Skylon and rapid reuse
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.
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.
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
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.
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.
As I said before, the company is clearly more flexible than people trying to "defend" the company.
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”.
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.
[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.
Seems like REL may have some competition in this area & LM hope to fly their demonstrator by 2018.Quotehttps://www.flightglobal.com/news/articles/lockheed-pushing-1-billion-mach-6-airbreather-423198/
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...
Seems like REL may have some competition in this area & LM hope to fly their demonstrator by 2018.Quotehttps://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.
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.
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.
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.
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
They put the engines on the wingtips because they are near the center of gravity.
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.
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.For legal reasons I would not call him a con man.
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.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.
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.
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".
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.pdfWould 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?From the report, it would appear your understanding is correct:
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."
So, what form is this single engine SABRE demonstrator likely to look like - something like the Lockheed D21 drone perhaps?
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.pdfWould 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?
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:QuoteMark 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?
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.
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?
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.
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.
A scramjet can go up to Mach 10.
Mach 5 you can do with a turboramjet, to my knowledge.
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.
This was the original REL concept for a Nacelle Test Vehicle:
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. :(
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. :(
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.
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.
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
The scramjet research and the people involved have no sensible bearing on space launch, so why the hell ask them to comment on SABRE?
Actually there are also the groups who build ramjets for missiles.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.
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.
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}
They didn't go to investors at all Musk was rich enough to fund F1 and F9.
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 :pA fair point.
Upper scale is existing infrastructure.
They didn't go to investors at all Musk was rich enough to fund F1 and F9.
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.
REL have had to justify every penny they have been given.
(it really helps that Kourou has cleanroom standard vehicles with an airlock for moving things between buildings)
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.
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
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.
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.They didn't go to investors at all Musk was rich enough to fund F1 and F9.
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.
REL have had to justify every penny they have been given.QuoteAnd 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 :pA fair point.
Except what LM is looking into longer term for its air breathing vehicle isn't a pure scramjet.
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.
US military to reveal Skylon-based launch vehicle
http://www.rocketeers.co.uk/node/4613
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.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
US military to reveal Skylon-based launch vehicle
http://www.rocketeers.co.uk/node/4613
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.
Who are you talking about? HOTOL was not a LACE system.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.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
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?
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.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?
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.
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.
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.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
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."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.
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.
Except what LM is looking into longer term for its air breathing vehicle isn't a pure scramjet.QuoteHewson 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/
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."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
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.
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.
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.
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.
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 :)I didn't recall the exact starter Mach number.
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 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
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 amountI 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. :(
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...I'm quite a fan of novel clean energy concepts myself. :)
(Sorry that was tacky but true:( )
I didn't recall the exact starter Mach number
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.
QuoteI 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 ?
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.
I though the temperature of the intake air also became a problem above this speed?
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/
LM kept dropping the goal all the way to cancelation which was Mach-6
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
QuoteLM kept dropping the goal all the way to cancelation which was Mach-6
Oh damn, was it THAT worse ? >:(
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.this? http://enu.kz/repository/2011/AIAA-2011-5688.pdf
Any help would be fantastic.
Editted to add:
or this http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=30547.0;attach=534797
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.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?
When ambient pressure drops to near vacuum do Skylon tank pressures drop to 1 atm absolute, during powered flight??
Mark Thomas will be a speaker at this conference in May:May be we will get something new, they been quiet since December.
http://www.aerosociety.com/Events/Event-List/2197/What-Price-Speed
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
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...)
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.
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%!So you don't really know anything, but you're sure the number have been fudged. Is that about it?
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.
rockets on the drawing board often don't turn out to be as good as the designers hopedLike?
rockets on the drawing board often don't turn out to be as good as the designers hopedLike?
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?
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.
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).
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.
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.
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.
And if an ant were as big as an elephant it could lift 10 tonsExactly. 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.
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.
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.
Anyway,This is a most interesting post but I think you're starting numbers are a bit off.
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)
Anyway,This is a most interesting post but I think you're starting numbers are a bit off.
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)
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.
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".
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.
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.
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.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.
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.
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.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.
. . . They get there, at least after upgrades.
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.
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 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"Or we could use the figures from V 2.0 of the Skylon Users Manual figures.
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.
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"Or we could use the figures from V 2.0 of the Skylon Users Manual figures.
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.
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.
wiki now has 2000 kN per engine, still at T/W of "up to 14"I take it you failed to notice the "citation needed" note on the 14:1 statement in wikipedia's Skylon article?
Maybe I've misinterpreted something, or maybe wiki's got it wrong, or maybe those growth problems are happening for Skylon.
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.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 . . .
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.
Which SABRE? do you have a source?
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.
Skylon user Manual 2.1 shows 2MN peak thrust for air breathing and 2MN thrust for rocket.
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?
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.
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.
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.
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 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.
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.
The UK is a possible site for polar launches
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.
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.
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.
As I said the spaceport isn't about Skylon, but they may use it for testing.I don't think anyone thought it was.
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?
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)
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)
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.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.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?
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.pdfThe 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.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?
A quite outdated paper I believe, as it does not match their own minimal numbers... would you mind to send me the reference paper?
this guy actually gave a presentation
He claims to work at REL
this guy actually gave a presentation
Yes he did; to REL on the date shown.QuoteHe 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.
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.
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.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.
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.
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"
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!
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).
http://forum.nasaspaceflight.com/index.php?topic=24621.msg735577#msg735577jongoff 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.Quote from: HempsellWe 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.
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.http://forum.nasaspaceflight.com/index.php?topic=24621.msg735577#msg735577jongoff 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.Quote from: HempsellWe 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.
So I wonder if Skylon could halve the cost (and development time) if they went for a ~3 ton payload instead of 10-15.
Skylon already has a Skylon Upper Stage
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.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.http://forum.nasaspaceflight.com/index.php?topic=24621.msg735577#msg735577jongoff 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.Quote from: HempsellWe 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.
So I wonder if Skylon could halve the cost (and development time) if they went for a ~3 ton payload instead of 10-15.
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.
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 ?
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).
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
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?The article still thinks this is for a LACE cycle.
http://nextbigfuture.com/2016/06/us-air-force-research-will-develop.html
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
It may be easier to obtain funding for a new class of engine that can be strapped to an existing vehicleWhat 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
than to punt for a novel engine for a novel vehicle which requires novel infrastructure? or to put it anouther wayThis 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.QuoteAFRL officials views a single-stage-to-orbit Skylon space plane as "technically very risky as a first application [...]
Note for maximum cost reduction the engines and airframes must be identical.
Such a design needs 2 engines and 2 airframes to get funded, develop and test.
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.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.
One miracle at a time.
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.
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.
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.
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.
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.
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.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.
One miracle at a time.
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.
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
No one goes to a biamese design for performance.
You seem to be under the impression there is a shortage of space launch systems.
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.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.
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.
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.
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.
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!
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.
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.
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.
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.QuoteI 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.
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.
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.
QuoteI 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?
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?
Blunt-body reentry with high gees and ablative shielding add less mass than wings would.As Dyansoar and Hermes "proved." :(
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?
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.
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.
QuoteI 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.
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.
Opinion | Reviving The Aerospace Plane ProgramRead it. If you know the subject it's hilarious. :)
http://spacenews.com/reviving-the-aerospace-plane-program/
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!)
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.
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!)
They refuse flat out discussed the work Reaction Engines have undertaken for the MOD, only saying they done work for the MOD.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.
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.
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 ?.
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.
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.
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 !
Thanks for bringing me back to present day (freudian slip).They aren't called that either.
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.
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.
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.True. The nicest short description of hypersonic cruise is "continuous re-entry."
Seriously - go for skylon !
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.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.QuoteBond 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.
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.
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 !
In one of the REL reports key items listed in 3a (from memory can't find the report).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?
They aren't called that either.
It's BAe Systems.
It's BAe Systems. And their nearest counterpart is neither Boeing or even ULA, it's LM.
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.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.
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.
A tweet from REL states "We've strengthened our management team and opened a US Office".The biggest news here is Reaction Engines actually have a Twitter Account! I thought this whole PR mullarkey was beyond them.
https://twitter.com/ReactionEngines/status/752487279814406144
link to their news update
http://www.reactionengines.co.uk/news_11jul2016.html
And their nearest counterpart is neither Boeing or even ULA, it's LM.... Dr. Dissel joins Reaction Engines Inc. from Lockheed Martin Space Systems
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.
According to the Financial times it has funding,Nothing but pay wall on that link.
https://next.ft.com/content/f879fe82-4782-11e6-8d68-72e9211e86ab (https://next.ft.com/content/f879fe82-4782-11e6-8d68-72e9211e86ab)
According to the Financial times it has funding,Nothing but pay wall on that link.
https://next.ft.com/content/f879fe82-4782-11e6-8d68-72e9211e86ab (https://next.ft.com/content/f879fe82-4782-11e6-8d68-72e9211e86ab)
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.”
.
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.
I'd be very careful of wholesale posting of a copyright item. :(
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.
I'd be very careful of wholesale posting of a copyright item. :(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.
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.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.
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.
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.
Just hope Brexit doesn't blow this whole project off course.Or this thread, yet again.
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."
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.
At this rate perhaps we should Brexit more often... ;)I've never heard of Orbital Access Limited before.
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
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.
At this rate perhaps we should Brexit more often... ;)I've never heard of Orbital Access Limited before.
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
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.
At this rate perhaps we should Brexit more often... ;)Wonder if that means Prestwick has now become the favourite to host the UK spaceport.
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-36773074QuoteBut 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
At this rate perhaps we should Brexit more often... ;)I've never heard of Orbital Access Limited before.
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
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?
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.
That a shame, they kept that announcement pretty quiet.
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.
ESA on SABRE:
http://tinyurl.com/zuerv9z (was a massive ESA URL, so shortened it).
First rule of PR.
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 ;DIf 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.
First rule of PR.
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!
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.QuoteI shouldn't be so churlish though. At least there's progress ;DIf 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.
Just hope Brexit doesn't blow this whole project off course.
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?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.
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.
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?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.
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.
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?
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?
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?
...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)
...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.
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.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?
QuoteWhat'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 ..
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.
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 pumpsWhen did you see that information? Pressure fed was being talked about when Mark Hempsell was still with REL.
Indeed.QuoteWhat'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.
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.
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.
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 costsQuote...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.
on intermediate products, VAT is usually refundable so it shouldn't impact costs... not sure how it works in UK however.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.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?
{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 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.
RV confirmed SABRE is designed to be a SSTO engine, but they're investigating TSTO concepts.Wasn't thinking about other unmanned craft until this...
Hypersonic passenger transport is too expensive to be practical at the moment. Not going to go into other unmanned craft in this talk.
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)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." :(
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)
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,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....
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)
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.
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. :(
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. :)
the C1 engine was designed to run at 100-200 bar, as is required for the high SI.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.
The air breathing engines in SABRE 4 are more likely to be around 20.
Unrelated, Alan Bond is one of the most charismatic people I've met. I wouldn't trust myself to objectively judge anything he said.
Wasn't thinking about other unmanned craft until this...
[...] plum impingement [...]
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.
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...
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.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.
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.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.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.
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.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.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.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.
Outside the material Skylon's design is quite conventional,
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...
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"
...... 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.
...... 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....... 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.In 1903 maybe, by 1914 Sperry had already demonstrated an autopilot
(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.
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.
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.
'detachable' carbo bay that can be preloaded and quickly swapped upon landing...Much like how most passenger luggage is shipped in fact.
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. :(
[Wright Bros and 747s.]
'detachable' carbo bay that can be preloaded and quickly swapped upon landing...Much like how most passenger luggage is shipped in fact.
It's that kind of exaggeration that makes people so sceptical of the continual claims that Skylon has no "showstoppers".
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.
I used the phrase "passenger luggage" very specifically to denote the sort of boxes used to speed up passenger luggage handling at airports'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 airportsNo aircraft uses a detachable cargo section that must function as an integrated part of the vehicle. ULD's are not even remotely analogous.'detachable' carbo bay that can be preloaded and quickly swapped upon landing...Much like how most passenger luggage is shipped in fact.
https://en.wikipedia.org/wiki/Unit_load_device
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.
SABRESkylon is a high risk/high cost/high reward programme
I used the phrase "passenger luggage" very specifically to denote the sort of boxes used to speed up passenger luggage handling at airportsNo aircraft uses a detachable cargo section that must function as an integrated part of the vehicle. ULD's are not even remotely analogous.'detachable' carbo bay that can be preloaded and quickly swapped upon landing...Much like how most passenger luggage is shipped in fact.
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.
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?"
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.
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.
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.
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.
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.
fully reusable TSTO when they said they could with F9, but in fact can't.
Big risk, big gains. Anyone who tells you different is either rigging the game or about to take you for a bag of cash.
SABRESkylon has had that assessment and there are no holes.
..."In fact," you are false.
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. ...
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.QuoteSABRESkylon 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.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 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...
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.
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.
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? :(
I'd say SX's failure to make F9 upper stage reuse work
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.
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.
...... 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. :)
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.
Really "epic" patent fight "Wright vs Curtis", folks should google it... :)
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. :(
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.
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?
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.
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.
I come to this thread to read about Sabre and Skylon, not endless rehashing of how SpaceX is better than everything.
As for confidence. We know 3 vehicles have demonstrated winged reentry from full LEO velocity.
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.
QuoteNew 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.
Quotededicated 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.
Quote'detachable' carbo bay that can be preloaded and quickly swapped upon landing...Much like how most passenger luggage is shipped in fact.
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.
QuoteNew 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.
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.
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.
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.
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.
(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.
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.
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.
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.
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
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"
I doubt you've ever paid any attention to how aircraft passenger luggage is shipped. It mostly uses these things.QuoteMuch 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).And the aircraft involved has even been named on this thread, which makes your inability to find it even worse....
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.
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.