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Commercial and US Government Launch Vehicles => Commercial Space Flight General => Topic started by: Chris Bergin on 08/02/2016 07:31 PM

Title: The Reaction Engines Skylon/SABRE Master Thread (6)
Post by: Chris Bergin on 08/02/2016 07:31 PM
Sixth thread for Reaction Engines/Skylon.

Previous: The Reaction Engines Skylon Master Thread (5)
https://forum.nasaspaceflight.com/index.php?topic=36826.0

This has to be on topic and civil. This is for sensible debate and updates. Anything trivial or stupid will be deleted without notice.

And I mean it. Anyone trolling will get their posts removed. Anyone repeat trolling will be banned. Quote people accurately (as in the way the forum intended).
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: oddbodd on 08/03/2016 12:31 AM
Quote from: high road
Quote from: john smith 19
Quote from: high road
dedicated landing strips,
Wrong again. A dedicated launch runway to orbit, but in air breathing only mode Skylon can take off from a much wider range of runways. Most of the length is to meet emergency stop criteria for the fully loaded vehicle, which only apply when it's fully loaded to go to orbit. Landing is much easier with a low empty weight and no engine noise issues.
That's what I said. The Skylon needs a dedicated runway to get to orbit. Using the SABRE engine for an airplane doesn't require the Skylon design.

Apologies for being a pedant, but you said dedicated landing strips initially. As designed Skylon only needs a dedicated runway for full load take off to orbit. On descent from orbit (or inter-airport/spaceport transfer) a standard runway would be usable because the vehicle would be much, much lighter and would not need the additional length. For empty landing pretty much any common major airport runway would suffice. For take off for inter-airport/spaceport there might be some questions about the hot exhaust from the SABRE engines. However because the vehicle would be much lighter I think the expectation is that the engines would not be on full thrust, so the exhaust would not cause damage. Again this is not expected to be a common occurrence, just in the event that the Skylon cannot reach home base for some reason.

Also, even if you meant dedicated orbital launch runway, can you really count that against Skylon? It's not like I can launch an orbital rocket from any old local runway either. Sure the orbital launch runway doesn't exist yet, and will cost a lot to make, but nor did Cape Canaveral exist until it was needed, and I'm pretty sure it cost a lot to build too.

As an illustration of how easily many airports could temporarily host a Skylon, the Antonov has a max take-off load of 640 T (metric), and that has taken off and landed all over the place. The heaviest landing was 285 T (dry-mass) + 247 T (payload) + some fuel reserve, so over 530 T.

For comparison the dry-mass of an empty Skylon is projected to be around 55 T, potentially with a <20 T payload, if transporting something down from orbit for landing. If taking off for inter-airport/spaceport transfer then hydrogen fuel (max of 66 T) would be needed, but no oxidizer (150 T).  It's not clear how much fuel would be needed to self ferry at a sub-sonic speed, but probably a lot less than 66 T. All meaning that Skylon would not need a dedicated takeoff runway in this worst case non-orbital scenario. Just leaving out the heavy oxidizer means the engines can be throttled back significantly. In fact the fully laden take off mass of a Skylon not going to orbit would be around 140-150 T. That's about 2/3 the mass of an empty, un-fueled Boeing 747-8F- the freight/cargo plane.

The only real question mark I can think of is whether the design can get the nose up enough for many runways, as Skylon has a shallow ascent profile in air-breathing mode and I believe the design does not have a lot of control surfaces. Perhaps without the oxydizer and a reduced hydrogen load, the limited control surfaces and trimming the fuel in the front and rear tanks will be enough for a more aggressive angle, and once up at altitude trim it back to neutral.

Obligatory: https://xkcd.com/386/ (https://xkcd.com/386/)
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: high road on 08/03/2016 06:28 AM

Yes, I did say landing strip. My language doesn't make a difference between the two, so I mistakingly used the literal translation.

This was a reaction to the post that the Skylon is a pretty common design. It's not. That doesn't mean it's impossible, but it's not ordinary. There's quite a lot of new stuff that needs to be built and/or tested for the first time.

But, as I've said before, I'm trying to avoid this continuous exchange of opinions, at least until the SABRE is finished and there's something concrete to talk about.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/03/2016 08:33 AM
For take off for inter-airport/spaceport there might be some questions about the hot exhaust from the SABRE engines.
Noise is more likely to be the issue. A Skylon on full thrust is equivalent to about the thrust of 2 1/8 Airbus 380's. Due to the higher velocity exhaust that's likely to an underestimate. OTOH without O2 on board that's about 150-160 tonnes lighter.
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However because the vehicle would be much lighter I think the expectation is that the engines would not be on full thrust, so the exhaust would not cause damage. Again this is not expected to be a common occurrence, just in the event that the Skylon cannot reach home base for some reason.
Depends. It does allow the Skylon to be kept at a home country airport then flown down to an equatorial for the flight to orbit.
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Also, even if you meant dedicated orbital launch runway, can you really count that against Skylon? It's not like I can launch an orbital rocket from any old local runway either.
It was noted that a Skylon wheel loading is around that of the old B36. The USAF still has 4 runways that were rated for this aircraft and IIRC it also visited RAF Mildenhall, although I'm not sure if that runway was cleared for the full take off weight.  Obviously due to their inclination they would not allow a full payload to orbit, noise is still likely to be an issue (even being military runways) and getting permission on what are (AFAIK) still active SAC bases would be tricky. But it's not exactly cutting edge technology.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Ravenger on 08/03/2016 09:21 AM
Without fuel Skylon will be light enough to be towed by another aircraft. As an alternative to self-ferry it has advantages (mainly saving on engine wear and tear).  So that's another option if Skylon lands at a standard airstrip and needs to be transported back to the launch site.

I'm not sure what type of towing aircraft would be required, and it remains to be seen how practical this would be. It'd be a pretty impressive sight given the size of the spaceplane. The largest glider ever built was the Me 321 Gigant, and that was 'only' 28m long, compared to Skylon's proposed 83m length.

Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Hankelow8 on 08/03/2016 09:42 AM
At a recent talk by Richard Varvill for the BIS Space Conference at Charterhouse, he showed a drawing of a Sabre
ground test engine with a single exhaust chamber not the normal 4 chamber combination .

He stated they expect to have the engine running by 2019, he also showed what appeared to be a single engine test  flight model similar to the BAE Systems recent video.

In chat at the conference it seems  Sabre 4 will have a moveable inner high altitude thrust chamber.

When asked what the single engine flight vehicle will cost to build and fly he said around 1 billion, when asked where the money is for this, he just shrugged his shoulders !!
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: MarekCyzio on 08/03/2016 10:39 AM
Without fuel Skylon will be light enough to be towed by another aircraft. As an alternative to self-ferry it has advantages (mainly saving on engine wear and tear).  So that's another option if Skylon lands at a standard airstrip and needs to be transported back to the launch site.

I'm not sure what type of towing aircraft would be required, and it remains to be seen how practical this would be. It'd be a pretty impressive sight given the size of the spaceplane. The largest glider ever built was the Me 321 Gigant, and that was 'only' 28m long, compared to Skylon's proposed 83m length.

I seriously doubt this could be possible. Not because of Skylon weight, but because of take off speed and necessary rotation angle.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Ravenger on 08/03/2016 01:26 PM
I seriously doubt this could be possible. Not because of Skylon weight, but because of take off speed and necessary rotation angle.

I agree it sounds improbable - but it was Alan Bond himself who suggested it when I asked him about self-ferrying at a Sabre / Skylon talk.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: oddbodd on 08/03/2016 06:30 PM
Without fuel Skylon will be light enough to be towed by another aircraft. As an alternative to self-ferry it has advantages (mainly saving on engine wear and tear).  So that's another option if Skylon lands at a standard airstrip and needs to be transported back to the launch site.

I'm not sure what type of towing aircraft would be required, and it remains to be seen how practical this would be. It'd be a pretty impressive sight given the size of the spaceplane. The largest glider ever built was the Me 321 Gigant, and that was 'only' 28m long, compared to Skylon's proposed 83m length.



Gotta love those crazy Germans in WW2. Coming up with all kinds of crazy stuff. With the Me 321 Gigant having a max take-off mass of ~34 T, then it seems that the mass itself wouldn't be an issue with modern power/materials/engineering. I just wonder how much reinforcement the two vehicles structures would need to handle the stresses at the towing points from take-off and in-flight turbulence. Modern freight planes (Boeing 747-8F) can dead-lift much greater mass (max cargo of 140 T), and Skylon being a winged lifting body would lift itself, although with a penalty of course for the extra drag the cargo plane has to overcome.

Just the idea makes my head spin a little though :-) I'm not someone who goes to airshows or nerds out at the end of runways, but I think even I'd have to go see a 747-8F take off towing a Skylon. Then I'd chase the thing to watch the Skylon take-off under it's own power :-)

I seriously doubt this could be possible. Not because of Skylon weight, but because of take off speed and necessary rotation angle.

I'm not an aeronautical engineer, so please excuse the question(s)/statement(s) if they're dumb - I'm just going off of instinct on these. Can you explain a bit why you think TOS and RA are an issue? If I have a cargo plane (the aforementioned mentioned 747-8F) dragging an empty Skylon into the air (only ~55 T) then it is going up regardless... it may be damaged, but it'll go up. The wings on the Skylon are intended to get ~300 T into the air, and although I'm not sure how high the TOS is at 300 T, surely the TOS at 55 T is a lot less and would be OK with a cargo planes lower TOS.

I also don't get why RA is an issue. As the Skylon is empty, then again the front canards that provide some small rotational authority will have a much bigger effect due to low mass, plus you have the cargo plane physically pulling the cable upwards a little as it takes off. You'd just need to make sure not to rotate too fast, catching the Skylon tail on the runway. Once Skylon clears the ground, it's just down to how much power the cargo plane engines can deliver as to how steeply you can climb. Which is a lot. Don't forget that Skylon has a very steep climb angle in the rocket phase of an orbital launch, so it shouldn't have any trouble with a steep angle in tow mode instead of an orbital shallow take-off angle.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/04/2016 12:17 AM
He stated they expect to have the engine running by 2019, he also showed what appeared to be a single engine test  flight model similar to the BAE Systems recent video.
This is the obvious way to turn a single flight weight test engine into a flight vehicle but the configuration has some real problems. The lack of a fuselage makes LH2 storage tough even with the reduced LH2 consumption of the SABRE 4 cycle, and of course it's aerodynamics will be quite different to the Skylon configuration.

On the upside it can give solid flight confidence of the inlet design. Ideally this would be over the full airbreathing range. Going a bit beyond that, to full inlet closure and the transition to full rocket mode would retire a lot of the outstanding concerns about the SABRE cycle, since we know it would operate as a rocket engine from then to orbit.
Quote
When asked what the single engine flight vehicle will cost to build and fly he said around 1 billion, when asked where the money is for this, he just shrugged his shoulders !!
Which you may interpret as "I have no idea" or "I know exactly where it's coming from, but I'm not going to say."

Finance has always been the issue with SABRESkylon. I believe the key is to find a way to turn customer interest into a binding "pre-agreement," with no money up front but an absolute commitment to purchase at a set price (adjusted to track inflation) if the finished product meets certain stated criteria. The results of these negotiations would have to be in a form that can be transferred to the consortium that will make the Skylons to fulfill

With a batch of these in the bank REL would be in a much stronger position to encourage the formation of such a consortium and the consortium would be in a much stronger position to raise finance, since in principle they have already been sold.

The nearest thing I'm aware of to this is in large construction projects, where sub contractors are "novated" from the design team to construction team, but it would be quite a tricky piece of both international contract law and finance to make work.  :(
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: CameronD on 08/04/2016 04:57 AM
Finance has always been the issue with SABRESkylon. I believe the key is to find a way to turn customer interest into a binding "pre-agreement," with no money up front but an absolute commitment to purchase at a set price (adjusted to track inflation) if the finished product meets certain stated criteria. The results of these negotiations would have to be in a form that can be transferred to the consortium that will make the Skylons to fulfill

With a batch of these in the bank REL would be in a much stronger position to encourage the formation of such a consortium and the consortium would be in a much stronger position to raise finance, since in principle they have already been sold.

The nearest thing I'm aware of to this is in large construction projects, where sub contractors are "novated" from the design team to construction team, but it would be quite a tricky piece of both international contract law and finance to make work.  :(

At least with a novated construction contract for, say, a high-rise building you know you're going to get a high-rise building at the end of the day: with SABRESkylon you could get nothing.

As I see it, the issue with SABRE/Skylon is that they have yet to demonstrate their technology works.  Perhaps one day they will.. but until then no-one should be surprised by the lack of commercial interest.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Dalhousie on 08/04/2016 05:08 AM

As I see it, the issue with SABRE/Skylon is that they have yet to demonstrate their technology works.  Perhaps one day they will.. but until then no-one should be surprised by the lack of commercial interest.

REL have demonstrated quite a bit of the technology works at the bench top level - the pre cooler, inlets, the nozzles under both cold and hot flow conditions.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: CameronD on 08/04/2016 05:22 AM

As I see it, the issue with SABRE/Skylon is that they have yet to demonstrate their technology works.  Perhaps one day they will.. but until then no-one should be surprised by the lack of commercial interest.

REL have demonstrated quite a bit of the technology works at the bench top level - the pre cooler, inlets, the nozzles under both cold and hot flow conditions.

That's nice... so when will they be testing a complete engine??  ::)

(Note: I'm not even asking for a real, flying Skylon, noooo that would be too much.  Nor even a fully-functioning flight article.. no,  how's about a single test engine strapped to a single test aircraft?  Is that too much to ask?? )
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/04/2016 08:45 AM

That's nice... so when will they be testing a complete engine??  ::)
On the assumption you're not trolling and simply don't follow this subject closely they expect to do a full engine test in 2019-2020, as always subject to full funding.
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(Note: I'm not even asking for a real, flying Skylon, noooo that would be too much.  Nor even a fully-functioning flight article.. no,  how's about a single test engine strapped to a single test aircraft?  Is that too much to ask?? )
I'll guarantee it'll be before anyone builds anything with a SCramjet that does anything useful beyond demonstrate you can build an SCramjet whose thrust exceeds its drag.  :)
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Jim Davis on 08/04/2016 12:50 PM

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(Note: I'm not even asking for a real, flying Skylon, noooo that would be too much.  Nor even a fully-functioning flight article.. no,  how's about a single test engine strapped to a single test aircraft?  Is that too much to ask?? )
I'll guarantee it'll be before anyone builds anything with a SCramjet that does anything useful beyond demonstrate you can build an SCramjet whose thrust exceeds its drag.  :)

You're damning Skylon/SABRE with faint praise. :)
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/04/2016 03:42 PM

Quote
(Note: I'm not even asking for a real, flying Skylon, noooo that would be too much.  Nor even a fully-functioning flight article.. no,  how's about a single test engine strapped to a single test aircraft?  Is that too much to ask?? )
I'll guarantee it'll be before anyone builds anything with a SCramjet that does anything useful beyond demonstrate you can build an SCramjet whose thrust exceeds its drag.  :)

You're damning Skylon/SABRE with faint praise. :)
Well I should admit that SCramjets have probably generated more hypersonics PhD's than deeply pre cooled turbo rockets, much the way fusion research has lead the world in producing plasma physics PhD's.

In fact I expect REL (funding willing) will produce a flight vehicle before other more highly advertized concepts become anything more than clever looking Powerpoints. Never mind leaving the ground.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 08/04/2016 04:04 PM
I'm just looking forward to an all-up engine test within the mentioned time frame, hopefully sooner.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Lars-J on 08/04/2016 07:42 PM
Finance has always been the issue with SABRESkylon. I believe the key is to find a way to turn customer interest into a binding "pre-agreement," with no money up front but an absolute commitment to purchase at a set price (adjusted to track inflation) if the finished product meets certain stated criteria. The results of these negotiations would have to be in a form that can be transferred to the consortium that will make the Skylons to fulfill

With a batch of these in the bank REL would be in a much stronger position to encourage the formation of such a consortium and the consortium would be in a much stronger position to raise finance, since in principle they have already been sold.

The nearest thing I'm aware of to this is in large construction projects, where sub contractors are "novated" from the design team to construction team, but it would be quite a tricky piece of both international contract law and finance to make work.  :(

I sympathize with your frustration, because it is such an a**-backwards business plan. (if accurate) If they have any interest in bringing Skylon to reality, REL needs to LEAD this consortium, not hope that someone else will do it. They need to become the prime contractor.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: ChrisWilson68 on 08/04/2016 08:32 PM
Finance has always been the issue with SABRESkylon. I believe the key is to find a way to turn customer interest into a binding "pre-agreement," with no money up front but an absolute commitment to purchase at a set price (adjusted to track inflation) if the finished product meets certain stated criteria. The results of these negotiations would have to be in a form that can be transferred to the consortium that will make the Skylons to fulfill

With a batch of these in the bank REL would be in a much stronger position to encourage the formation of such a consortium and the consortium would be in a much stronger position to raise finance, since in principle they have already been sold.

I've never seen any evidence at all of any potential customer with the financial resources to matter having any interest in such a "pre-agreement".

And, even if they did by some miracle get those pre-agreements in place, that doesn't automatically mean they'd get development funding because the pre-agreements only address market risk, not development risk.  If I go around and get 100 people to agree to buy my anti-gravity device if it works, that doesn't mean I'll get funding because there's still the substantial risk that I can't actually make an anti-gravity device to fulful the terms of the pre-agreements.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: ChrisWilson68 on 08/04/2016 08:42 PM
Is it possible to have a polite discussion about how SpaceX and Blue Origin affect Reaction Engines without it going off-course into a shouting match about whether SpaceX can't or didn't choose to build a reusable second stage?  I hope so, because I think it's an important issue for Reaction Engines.

The original value proposition of Skylon was versus the old state-of-the-art: expensive, expendable launch vehicles.  Now, the state of the art is changing.  As both Blue Origin and SpaceX move closer to inexpensive, reusable launch vehicles, it erodes the value proposition of Skylon in comparison.  It's one thing to say they want to spend $16 billion to produce a system that reduces launch costs from $250 million per launch to $5 million per launch.  It's a harder sell if the reduction is from $60 million to $5 million.  And even harder when the reduction is from $40 million, then $20 million, and so on.

On the other hand, having other competitors moving toward a low-cost launch system could prove and expand the market, giving investors confidence to invest in REL, particularly if Europe is afraid of the new low-cost launchers and wants its own alternative.

So, which is the bigger effect?  My opinion is that the changes in the market from Blue Origin and SpaceX will have much more of a negative effect on REL than a positive effect.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/05/2016 12:30 AM
I sympathize with your frustration, because it is such an a**-backwards business plan. (if accurate) If they have any interest in bringing Skylon to reality, REL needs to LEAD this consortium, not hope that someone else will do it. They need to become the prime contractor.
In REL's org chart there is a thing called "Skylon Enterprises. " I'll be watching that space.

REL are quite clear that the skillset for building a large aircraft is very different than that for building engines for such a vehicle.  They don't expect to lead that group, but they do expect to have a lot of input to it.

I think it's interesting that their position has moved from just the precooler (and maybe some other heat exchangers) to saying "Yes, we can do the whole engine, it's not beyond our resources"

But the fact remains people buy Airbuses, Boeings, Cessnas, Ariane's and F9, not P&W's, Rolls Royces, Lycomings, Vulcains or Merlins.   :(
I've never seen any evidence at all of any potential customer with the financial resources to matter having any interest in such a "pre-agreement".
Nice qualification of you disagreement. In fact it's basically how Steve Jobs bankrolled the Apple II and roughly how most  Boeings and Airbuses have had their finance raised for them.

What actually makes it difficult is the fact the organisation that would actively deal with the customers is not the final recipient of the money, and indeed that body would not exist in its final form (how could it, as those pledges would be a key part of bringing it into existence).   :(
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And, even if they did by some miracle get those pre-agreements in place, that doesn't automatically mean they'd get development funding because the pre-agreements only address market risk, not development risk.  If I go around and get 100 people to agree to buy my anti-gravity device if it works, that doesn't mean I'll get funding because there's still the substantial risk that I can't actually make an anti-gravity device to fulful the terms of the pre-agreements.
As I and others have  noted smart VC's have never invested in ideas, but in the teams behind them.

Your antigravity team would appear to be someone with no knowledge of physics, no working theory to make it happen and no prototype to show you even have the skills to make it if you wanted to.

So yes I can see you'd have a lot of trouble raising a cent.

REL OTOH has a solid track record of developing various parts of their concept. You'll only see them mentioned in passing but they indicate a substantial of projects completed and risks retired.

I'd suggest that's a lot more from day one that quite a few Silicon Valley startups have brought to the table. Mostly a belief that somehow they can make it work before the money runs out.

The original value proposition of Skylon was versus the old state-of-the-art: expensive, expendable launch vehicles.  Now, the state of the art is changing.  As both Blue Origin and SpaceX move closer to inexpensive, reusable launch vehicles,
That's a reusable sub-orbital in Blue's case and a semi reusable vehicle in SX's case. The distinctions have serious implications on economics.
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it erodes the value proposition of Skylon in comparison.  It's one thing to say they want to spend $16 billion to produce a system that reduces launch costs from $250 million per launch to $5 million per launch.  It's a harder sell if the reduction is from $60 million to $5 million.  And even harder when the reduction is from $40 million, then $20 million, and so on.
If that was all Skylon offers you'd be right, but that ignores it's life expectancy, which will be demonstrated, not guesse, it's launch reliability (and the only known semi reusable vehicle that's actually flown had a reliability of about 1 in 36, with root cause failures in the expendable or refurbished-to-the-point-of-being-rebuilt parts of the design)
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On the other hand, having other competitors moving toward a low-cost launch system could prove and expand the market, giving investors confidence to invest in REL, particularly if Europe is afraid of the new low-cost launchers and wants its own alternative.

So, which is the bigger effect?  My opinion is that the changes in the market from Blue Origin and SpaceX will have much more of a negative effect on REL than a positive effect.
We keep hearing about a how F9SR will change the market but none have launched so far and the market has to expand radically to offset the revue loss from the lower prices. My instinct is those prices are simply not low enough to actually bring many people flocking to SX with ideas that they've just been waiting to launch. So SX has a net revenue loss. Wheather or not it loses profit as well is another matter.

Sorry but $60m is better than $120m and $30 is better still but IMHO it's simply not that much better to double (or more than double ideally) the market. It's still a shedload of money (and that's not for a comm sat launch, just to LEO) for a ticket to ride with (hopefully) a reliability record that will be one day as be demonstrated to be as good as Ariane or Atlas and a launch date at the suppliers (any suppliers) convenience, not mine.

It's quite easy to run the numbers on the economics of the ELV business and very tough to beat them. A fully reusable F9 might have done it. For whatever reason it didn't happen.

I don't see F9SR being anywhere near the breakthrough in price you seem to think it is.  :(
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: CameronD on 08/05/2016 12:38 AM
The original value proposition of Skylon was versus the old state-of-the-art: expensive, expendable launch vehicles.  Now, the state of the art is changing.  As both Blue Origin and SpaceX move closer to inexpensive, reusable launch vehicles, it erodes the value proposition of Skylon in comparison.  It's one thing to say they want to spend $16 billion to produce a system that reduces launch costs from $250 million per launch to $5 million per launch.  It's a harder sell if the reduction is from $60 million to $5 million.  And even harder when the reduction is from $40 million, then $20 million, and so on.

On the other hand, having other competitors moving toward a low-cost launch system could prove and expand the market, giving investors confidence to invest in REL, particularly if Europe is afraid of the new low-cost launchers and wants its own alternative.

So, which is the bigger effect?  My opinion is that the changes in the market from Blue Origin and SpaceX will have much more of a negative effect on REL than a positive effect.

I'd second that opinion. ..and add that as 'low-cost launch' becomes more of the norm, REL may find themselves forced onto a different course.  The SST market stagnated with the demise of Concorde, but might be somewhere REL can carve out a place to play using their SABRE engines (in mostly air-breathing mode) and a much-modified, re-purposed Skylon.
 
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: ChrisWilson68 on 08/05/2016 04:09 AM
I've never seen any evidence at all of any potential customer with the financial resources to matter having any interest in such a "pre-agreement".
Nice qualification of you disagreement. In fact it's basically how Steve Jobs bankrolled the Apple II and roughly how most  Boeings and Airbuses have had their finance raised for them.

Which has exactly nothing to do with my point.

My point is about Skylon in particular, not about whether people are willing to sign agreements to buy other products before they are developed.

What actually makes it difficult is the fact the organisation that would actively deal with the customers is not the final recipient of the money, and indeed that body would not exist in its final form (how could it, as those pledges would be a key part of bringing it into existence).   :(

Or, people with money just don't think Skylon is a good bet.

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And, even if they did by some miracle get those pre-agreements in place, that doesn't automatically mean they'd get development funding because the pre-agreements only address market risk, not development risk.  If I go around and get 100 people to agree to buy my anti-gravity device if it works, that doesn't mean I'll get funding because there's still the substantial risk that I can't actually make an anti-gravity device to fulful the terms of the pre-agreements.
As I and others have  noted smart VC's have never invested in ideas, but in the teams behind them.

Your antigravity team would appear to be someone with no knowledge of physics, no working theory to make it happen and no prototype to show you even have the skills to make it if you wanted to.

So yes I can see you'd have a lot of trouble raising a cent.

Again, you're not addressing my point at all.  My point is a simple one: getting pre-development purchase agreements only addresses market risk, not development risk.  Whether or not there is development risk for Skylon is not relevant to that point.  The point is just that pre-development purchase agreements aren't sufficient.

I'd suggest that's a lot more from day one that quite a few Silicon Valley startups have brought to the table. Mostly a belief that somehow they can make it work before the money runs out.

No Silicon Valley start-up has ever gone to a VC and presented a business plan that requires $16 billion in funding before the first revenue comes in and we find out if it works or not.

The original value proposition of Skylon was versus the old state-of-the-art: expensive, expendable launch vehicles.  Now, the state of the art is changing.  As both Blue Origin and SpaceX move closer to inexpensive, reusable launch vehicles,
That's a reusable sub-orbital in Blue's case and a semi reusable vehicle in SX's case. The distinctions have serious implications on economics.

I specifically asked that we avoid derailing this thread again arguing about whether SpaceX is capable of buidling a reusable second stage or not.

Can we just agree to disagree and move on?  You believe they're not capable of doing it.  Everyone else believes they chose not to for the near future but could at some point in the future much more easily than REL could build Skylon.  There.  Positions stated, nobody is going to change anyone's mind, so we can move on.

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it erodes the value proposition of Skylon in comparison.  It's one thing to say they want to spend $16 billion to produce a system that reduces launch costs from $250 million per launch to $5 million per launch.  It's a harder sell if the reduction is from $60 million to $5 million.  And even harder when the reduction is from $40 million, then $20 million, and so on.
If that was all Skylon offers you'd be right, but that ignores it's life expectancy, which will be demonstrated, not guesse,

Life expectancy for Blue Origin and SpaceX vehicles will be demonstrated, not guessed, long before Skylon will, so that's not a distinguishing characteristic of Skylon.

it's launch reliability (and the only known semi reusable vehicle that's actually flown had a reliability of about 1 in 36, with root cause failures in the expendable or refurbished-to-the-point-of-being-rebuilt parts of the design)

Are you really trying to convince anyone that Skylon is somehow likely to have better reliability than a Blue Origin or SpaceX vehicle because somehow you think the Blue Origin and SpaceX vehicles are more like that Space Shuttle than Skylon is?

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On the other hand, having other competitors moving toward a low-cost launch system could prove and expand the market, giving investors confidence to invest in REL, particularly if Europe is afraid of the new low-cost launchers and wants its own alternative.

So, which is the bigger effect?  My opinion is that the changes in the market from Blue Origin and SpaceX will have much more of a negative effect on REL than a positive effect.
We keep hearing about a how F9SR will change the market but none have launched so far

Surely if we're going to consider a world in which Skylon is actually built and meets its targets, we can consider the much, much smaller leap of Falcon 9 first stages, which already exist and which have already launched and landed successfully, eventually re-flying.

and the market has to expand radically to offset the revue loss from the lower prices. My instinct is those prices are simply not low enough to actually bring many people flocking to SX with ideas that they've just been waiting to launch. So SX has a net revenue loss. Wheather or not it loses profit as well is another matter.

For Skylon numbers to work out, the market would have to expand enormously at the $5 million price point.  I don't see how it's defensible to posit that there's so little elasticity in the market until $5 million but then suddenly at that price point there's an enormous elasticity.  Markets just don't tend to work that way.

Sorry but $60m is better than $120m and $30 is better still but IMHO it's simply not that much better to double (or more than double ideally) the market. It's still a shedload of money (and that's not for a comm sat launch, just to LEO) for a ticket to ride with (hopefully) a reliability record that will be one day as be demonstrated to be as good as Ariane or Atlas and a launch date at the suppliers (any suppliers) convenience, not mine.

There's no reason to think Skylon will have higher reliability than Blue Origin or SpaceX.  By the time Skylon flies, both of those others will have many years of experience getting those reliability rates very high.

And there's no reason that Blue Origin and SpaceX can't have some rockets sitting in the hangar ready to go at short notice, just like Skylon.

It's quite easy to run the numbers on the economics of the ELV business and very tough to beat them.

Running numbers is easy, but knowing what the market is is hard.  Skylon counts on a huge increase in launch rate.  Maybe it will happen, maybe not, but if it does, SpaceX and Blue Origin will be all over that.

A fully reusable F9 might have done it. For whatever reason it didn't happen.

It didn't yet happen.

I don't see F9SR being anywhere near the breakthrough in price you seem to think it is.  :(

It doesn't actually matter to my point.  My point is that if SpaceX and Blue Origin only ever get the price point to $60 million, that still hurts the value proposition of Skylon.  If they get it to $40 million, that hurts the value proposition even more.  $20 million even more.  At $5 million (Shotwell has told satellite operators to plan for that price point in the future), it entirely goes away.

Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: guckyfan on 08/05/2016 05:14 AM
It doesn't actually matter to my point.  My point is that if SpaceX and Blue Origin only ever get the price point to $60 million, that still hurts the value proposition of Skylon.  If they get it to $40 million, that hurts the value proposition even more.  $20 million even more.  At $5 million (Shotwell has told satellite operators to plan for that price point in the future), it entirely goes away.

If I was understanding john smith 19 correctly, those $5 million were refurbishment cost per flight. Add depreciation of Skylon and grund handling it will be somewhat more. Dividing $1B purchase cost by 200 flights alone will add another $5m, not counting other cost of ownership.
Title: The Reaction Engines Skylon Master Thread (6)
Post by: Star One on 08/05/2016 08:01 AM
Should be next month hopefully that we hear from the AFRL in relation to this topic from what I can remember.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 08/05/2016 03:51 PM
I sympathize with your frustration, because it is such an a**-backwards business plan. (if accurate) If they have any interest in bringing Skylon to reality, REL needs to LEAD this consortium, not hope that someone else will do it. They need to become the prime contractor.

Because Aerojet, Rocketdyne, GE, Rolls-Royce, and Pratt and Whitney have shown that engine manufacturers always have to be the "prime contractor" and take the LEAD in designing and building the vehicles their engines power... :)

The business plan is in fact rather normal as long as you realize that Blue Origins and SpaceX are not in fact 'normal' business' but aberrations, (granted paradigm changing ones so far but still not how things in aerospace have been run) from the norm. This doesn't mean either is superior or inferior than the other they are in fact different in methodology and long term goals so comparisons are usually misleading to the extreme.

Main point is that REL is finally getting enough interest to allow a consortium to be built around it's engine concept to attract enough professional interest to put to rest many of the general questions on the Skylon. What remains is the biggest and most important question of does the SABRE operate as planned in a 'full-up' manner which is the focus of current work and effort. Once that question is answered then full detail work can proceed on the actual "Skylon" system that will use it.

Who's business model "wins" in the end isn't something we can predict as history shows being 'first' very often does not mean you thrive from doing so, or even survive. (Wright aircraft is a good example of this) Modes, models and planning can be effected by false assumptions, logical falsehoods, bad timing and even fickle public opinion or regulatory interference. Being one of the first to get into the lead on the 'next-big-thing' can even work for a while before a change or two in something beyond your control turns it into a dead end, (Marquardt) and you end up on the loosing end of the equation. It's far to early to call winners and losers people.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Lars-J on 08/05/2016 06:15 PM
I sympathize with your frustration, because it is such an a**-backwards business plan. (if accurate) If they have any interest in bringing Skylon to reality, REL needs to LEAD this consortium, not hope that someone else will do it. They need to become the prime contractor.

Because Aerojet, Rocketdyne, GE, Rolls-Royce, and Pratt and Whitney have shown that engine manufacturers always have to be the "prime contractor" and take the LEAD in designing and building the vehicles their engines power... :)

They do have to if they hope to have any input in the design of the vehicle. Imagine SpaceX just building the Merlin 1D, and then only selling it if someone would build a Falcon 9 with it. Or an elevator builder selling blueprints for a skyscraper that someone needs to build for them. THAT is the backward part.

Nobody would bat an eye if REL was selling a neat engine that had its use for an air breathing vehicle. But instead they are trying to sell... Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Paul451 on 08/05/2016 06:37 PM
I sympathize with your frustration, because it is such an a**-backwards business plan. (if accurate) If they have any interest in bringing Skylon to reality, REL needs to LEAD this consortium, not hope that someone else will do it. They need to become the prime contractor.
Because Aerojet, Rocketdyne, GE, Rolls-Royce, and Pratt and Whitney have shown that engine manufacturers always have to be the "prime contractor" and take the LEAD in designing and building the vehicles their engines power...

AJ/RD/GE/etc don't propose aircraft. They are catering to an existing market. They anticipate that aircraft developers will keep developing newer models and will go looking for engines to power those models, so they try to push the technology further in the direction they think that market is going (more power, better fuel economy, lower maintenance costs) and sometimes they pick correctly and are selected, and sometimes they fail and have to scramble to catch up. But the basic aircraft design is never the engine manufacturer's. Not in large airliners, not in supersonic fighters, not cargo planes, not rocket launchers, not missiles.

Skylon is REL's design. Solely and utterly. Even moreso, it's mainly Bond's design.

There is no "market" of Skylon-type vehicle developers that is going to go looking for a suitable engine to power their future designs. Skylon is REL, REL is Skylon.

There's no comparison with engine companies. Hence this continual reference to conventional aircraft development makes no sense.

[In fact, the only time REL would be acting like a conventional engine company is with the proposal for LAPCAT and the 2STO proposal from the USAF.]
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/07/2016 02:08 PM
Which has exactly nothing to do with my point.
I'll deal with it more directly then. Why exactly would you expect to know? Do you have access to REL's internal paperwork?  I would suggest that "because I've not heard it" is not really proof of anything. Perhaps you weren't listening?
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Or, people with money just don't think Skylon is a good bet.
Which is just your first opinion repeated.
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Again, you're not addressing my point at all.  My point is a simple one: getting pre-development purchase agreements only addresses market risk, not development risk.  Whether or not there is development risk for Skylon is not relevant to that point.  The point is just that pre-development purchase agreements aren't sufficient.
I addressed exactly your point. pre-developmet purchase agreements address market risk. Study of REL's detailed track record would address their development risk.

Every large project has a development risks. Yes having put in a shed load of money it may prove impossible to make work.

OTOH Theranos demonstrated you could get a shedload of money, run for a decade and still not deliver a working product. 

You post like you understand these matters but you don't seem to.
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No Silicon Valley start-up has ever gone to a VC and presented a business plan that requires $16 billion in funding before the first revenue comes in and we find out if it works or not.
Such deep insight into REL's business plan. Do you work for them?  :)

In reality REL's plan has always been expected to have money released in tranches based on performance to targets. In reality once the consortium is up and running and Skylon is into it's development I'd expect some of those pre-sales agreements, based on actual progress to date, to turn into the first stage of an actual sale, especially if it gives them priority.
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I specifically asked that we avoid derailing this thread again arguing about whether SpaceX is capable of buidling a reusable second stage or not.
Perhaps you should read what I wrote instead of what you think I wrote?

You want to talk about now. Now is the F9SR.  Now is throwing away the upper stage on every launch. 

Later SX promise that BFR will be fully reusable. That should lower costs to them but will it lower prices? Only if all the payload is used.  That will give either a Shuttle sized rideshare problem or you'll want a single massive payload. That gives you the SLS payload problem. Who has a MW sized nuclear  reactor, or 15m telesope they want to launch?
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Are you really trying to convince anyone that Skylon is somehow likely to have better reliability than a Blue Origin or SpaceX vehicle because somehow you think the Blue Origin and SpaceX vehicles are more like that Space Shuttle than Skylon is?
What they are most like is a VTO ELV. Atlas V has demonstrate an unbroken list of 50+  launches and Ariane 5 64. so in principle you could have done all of them with the same 1st stage (certainly the Ariane flights with the same core, not sure about the Atlas V).

But Shuttle is the only vehicle which was designed for reuse and the vehicle was not a payload during launch. It failed at roughly 1 in 65 and the root cause was either the fully expendable parts or the heavily rebuilt parts, not the parts designed (mostly) for reuse.

So ELV's can be built with good launch reliability. Being able to study the actual damage to the F9 first stage can help improved the reliability of the first stage, but nothing about that of the upper stage.

All these designs have some things in common.  They have no intact abort option and for the ELV's "abort to orbit" is the best you can hope for as they have no down mass capability.

Skylon has no mission critical separation events to LEO and is designed to cope with a main engine fail. None of these vehicles could dump propellant and return to base. Skylon can, abort to a down range site or abort to orbit. It is also designed with full payload still on board. 

TL:DR  No.
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For Skylon numbers to work out, the market would have to expand enormously at the $5 million price point.  I don't see how it's defensible to posit that there's so little elasticity in the market until $5 million but then suddenly at that price point there's an enormous elasticity.  Markets just don't tend to work that way.
And you'd be wrong. What needs to happen is that there have to be people who want to own a vehicle, not a ticket to ride, and have the ability to launch a payload on their schedule, not a supplier in another country years in the future.
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There's no reason to think Skylon will have higher reliability than Blue Origin or SpaceX.  By the time Skylon flies, both of those others will have many years of experience getting those reliability rates very high.
There's a big difference between something that can eventually be made reliable and something that's reliable because what makes the first item unreliable (2nd stage separation, 2nd stage ignition, 2nd is always flying for the first, and only time, in its flight history) simply does not exist in the 2nd design.
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And there's no reason that Blue Origin and SpaceX can't have some rockets sitting in the hangar ready to go at short notice, just like Skylon.
The fact they are Blue's and SX hangars would speak volumes about the problem.
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Running numbers is easy, but knowing what the market is is hard.  Skylon counts on a huge increase in launch rate.
Again it does not. REL count on people wanting to own a vehicle not a (maybe) ticket to ride. They count on people wanting to own an asset they can resell, not a launch contract. They count on people wanting to launch on demand on a time scale of days, not months and they count on people who want to control their launch, not be controlled by their launch services provider.

Expanding the market is a consequence, not a requirement for REL success.  It is an absolute imperative for SX to maintain their profit stream if they are serious about cutting prices to customers.
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Maybe it will happen, maybe not, but if it does, SpaceX and Blue Origin will be all over that.
You said you don't want this to be an argument about designs. Why don't you stop doing what you don't want and talk about Skylon?
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It didn't yet happen.
When the CEO and Chief Designer of SX say's it's not going to happen I'm fairly sure it's off the table.
[EDIT So let me be clear. You claim to know that Elon Musk is wrong and he will change his mind on this? 

Wow. Your powers of insight are truly abnormal. Nor are you handicapped by excess modesty either. ]
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It doesn't actually matter to my point.  My point is that if SpaceX and Blue Origin only ever get the price point to $60 million, that still hurts the value proposition of Skylon.  If they get it to $40 million, that hurts the value proposition even more.  $20 million even more.
$20m will never happen while F9 has an expendable upper stage. A point that has been made repeatedly and which you keep ignoring.
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At $5 million (Shotwell has told satellite operators to plan for that price point in the future), it entirely goes away.
What a very selective memory you have.

Shotwell was saying that when SX thought they could still do a fully reusable F9 with enough payload to accommodate a full size comm sat to GTO.  That was in June of 2013

That's been off the table since Sept 2014.

Do you not understand what the words "no reusable upper stage based on F9 or F9 derived hardware" mean?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Robotbeat on 08/07/2016 05:35 PM
We need Reaction Engines to make significant progress to spare us from listening to arguments to why Falcon 9 or BFR are dumb.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Robotbeat on 08/08/2016 11:29 AM
Thank God for China, rescuing this thread from whining about SpaceX:

Looks like they're developing their own version of Skylon.

And good for them, as Europe is too timid to fully fund such a huge sum for the full-up space plane and Reaction Engines refuses to come up with a more practical, gradual plan to develop a reusable orbital vehicle.
http://www.spaceflightinsider.com/organizations/china-national-space-administration/china-develop-hybrid-spaceplane-cheaper-space-travel/
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: high road on 08/08/2016 01:03 PM

Won't that just replace whining about SpaceX with whining about Chinese spacecraft looking too much like 'existing' designs? Until they're first to actually launch one of these, that is.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: flymetothemoon on 08/08/2016 01:25 PM
Thank God for China, rescuing this thread from whining about SpaceX:

Looks like they're developing their own version of Skylon.

And good for them, as Europe is too timid to fully fund such a huge sum for the full-up space plane and Reaction Engines refuses to come up with a more practical, gradual plan to develop a reusable orbital vehicle.
http://www.spaceflightinsider.com/organizations/china-national-space-administration/china-develop-hybrid-spaceplane-cheaper-space-travel/

We knew this was coming. We've had several rumours. Congratulations Europe! Infuriating.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Star One on 08/08/2016 01:35 PM

Won't that just replace whining about SpaceX with whining about Chinese spacecraft looking too much like 'existing' designs? Until they're first to actually launch one of these, that is.

Well it makes a change from certain posters hyping up Space X on a REL thread
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 08/08/2016 01:38 PM
Thank God for China, rescuing this thread from whining about SpaceX:

Looks like they're developing their own version of Skylon.

And good for them, as Europe is too timid to fully fund such a huge sum for the full-up space plane and Reaction Engines refuses to come up with a more practical, gradual plan to develop a reusable orbital vehicle.
http://www.spaceflightinsider.com/organizations/china-national-space-administration/china-develop-hybrid-spaceplane-cheaper-space-travel/
"Knock-off artists champs"... :o For a nation with such a rich early history of civilization, have these people ever had an original idea in the last  100 years? ::)
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: momerathe on 08/08/2016 02:44 PM
Thank God for China, rescuing this thread from whining about SpaceX:

Looks like they're developing their own version of Skylon.

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It will rely on an indigenous turbine, ramjet, and rocket engines to power the spaceplane in various phases of flight.

Sounds like a multi-engine approach, rather than a single hybrid engine.

If they can make the design close with the mass penalty of three sets of engines, I will be very surprised.

Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: guckyfan on 08/08/2016 03:37 PM
"Knock-off artists champs"... :o For a nation with such a rich early history of civilization, have these people ever had an original idea in the last  100 years? ::)

Sorry, that's deeply unfair. Really original ideas are exceedingly rare today. If they make it when Europe isn't, who should blame them.

To bring the thread back to SpaceX.  ;) Whenever SpaceX has done something new, someone comes and claims it is not original. Someone has done that before.

Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 08/08/2016 03:47 PM
"Knock-off artists champs"... :o For a nation with such a rich early history of civilization, have these people ever had an original idea in the last  100 years? ::)

Sorry, that's deeply unfair. Really original ideas are exceedingly rare today. If they make it when Europe isn't, who should blame them.

To bring the thread back to SpaceX.  ;) Whenever SpaceX has done something new, someone comes and claims it is not original. Someone has done that before.
I have no problem with them building it if they pay REL for the licence to do so. Have a look at the aviation and space craft and you will see copies made of them since WWII with slight mods... On a general note they are not a nation of innovators but a communist system that demands conformity... Mass production yes, innovation not so much...
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: guckyfan on 08/08/2016 03:50 PM
On a general note they are not a nation of innovators but a communist system that demands conformity... Mass production yes, innovation not so much...

That's been said about Japan not so long ago, in my life perspective. But this is OT and I won't continue the discussion on this thread. If anyone opens a new thread.........
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/08/2016 04:43 PM
Sounds like a multi-engine approach, rather than a single hybrid engine.

If they can make the design close with the mass penalty of three sets of engines, I will be very surprised.
Indeed. They're going with a turbine/ramjet/rocket approach instead of the turbine/ramjet/SCRamjet approach which is a bit more sensible.

Chances of making it close on the mass is practically zero.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/08/2016 04:46 PM
"Knock-off artists champs"... :o For a nation with such a rich early history of civilization, have these people ever had an original idea in the last  100 years? ::)

Sorry, that's deeply unfair. Really original ideas are exceedingly rare today. If they make it when Europe isn't, who should blame them.

To bring the thread back to SpaceX.  ;) Whenever SpaceX has done something new, someone comes and claims it is not original. Someone has done that before.
Are you sure you're in the right forum?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 08/08/2016 08:01 PM
I sympathize with your frustration, because it is such an a**-backwards business plan. (if accurate) If they have any interest in bringing Skylon to reality, REL needs to LEAD this consortium, not hope that someone else will do it. They need to become the prime contractor.

Because Aerojet, Rocketdyne, GE, Rolls-Royce, and Pratt and Whitney have shown that engine manufacturers always have to be the "prime contractor" and take the LEAD in designing and building the vehicles their engines power... :)

They do have to if they hope to have any input in the design of the vehicle. Imagine SpaceX just building the Merlin 1D, and then only selling it if someone would build a Falcon 9 with it. Or an elevator builder selling blueprints for a skyscraper that someone needs to build for them. THAT is the backward part.

Nobody would bat an eye if REL was selling a neat engine that had its use for an air breathing vehicle. But instead they are trying to sell... Skylon.

But note what YOU said:
"I sympathize with your frustration, because it is such an a**-backwards business plan. (if accurate) If they have any interest in bringing Skylon to reality, REL needs to LEAD this consortium, not hope that someone else will do it. They need to become the prime contractor."

Doesn't seem that way to me as they've always said that Skylon is what they put together to answer questions on capability if fitted with SABRE rather than a "required" design. Further they have admitted, though it's a less than optimum design choice, that a TSTO based on SABRE is possible. The main question isn't about Skylon but about SABRE since it is what the entire concept hinges on.

So no, what you said above and what you said previously have nothing to do with each other as you ORIGINAL complaint was that "engine manufacturer" has to LEAD the design/construction consortium, not provide "input" into the design, on order to bring the design to fruition. You then follow with complaining that the "engine manufacturer" is in fact doing, (but isn't clearly) exactly what you demand they do?

REL is "selling" Skylon simply because as an engine SABRE requires certain design rules to be observed in order to get optimum performance out of the SABRE. I've yet to see anyone, (who isn't advocating SCramjets mind you) who doesn't understand and agree with the high-supersonic/low-hypersonic/orbital flight reasons they have done what they did. So in the end "Skylon" is the main design because at this point it answers all the right questions and REL has done enough work to satisfy investors/partners on that issue. The main issue is, and pretty much always has been, the engine and it's performance.

And for the most part people have been 'batting-an-eye' and going crazy over the engine itself despite the fact that most of the techniques and methods have been known in the aerospace community, (albeit by small and separated segments due to multiple programs and goals which despite aiming for something like the SABRE were more often conflicting and/or looking for different answers) for almost 50 years. The plain fact that it requires a different and what most consider "un-needed" (air breathing) design regime is simply another route to complain about the whole concept.

In truth you could have laid the plans for the SABRE down in front of the engineers and designers working on the Aerospaceplane project in the late 50s and they, (once they got it through their heads that oxygen doesn't require being liquid to pump into a rocket engine) and they would have fully understood the concept. Show the Skylon and other than advanced materials and technology they would have understood it and probably slapped themselves on the forehead for not seeing it themselves.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 08/08/2016 08:19 PM
AJ/RD/GE/etc don't propose aircraft. They are catering to an existing market. They anticipate that aircraft developers will keep developing newer models and will go looking for engines to power those models, so they try to push the technology further in the direction they think that market is going (more power, better fuel economy, lower maintenance costs) and sometimes they pick correctly and are selected, and sometimes they fail and have to scramble to catch up. But the basic aircraft design is never the engine manufacturer's. Not in large airliners, not in supersonic fighters, not cargo planes, not rocket launchers, not missiles.

Skylon is REL's design. Solely and utterly. Even moreso, it's mainly Bond's design.

There is no "market" of Skylon-type vehicle developers that is going to go looking for a suitable engine to power their future designs. Skylon is REL, REL is Skylon.

There's no comparison with engine companies. Hence this continual reference to conventional aircraft development makes no sense.

[In fact, the only time REL would be acting like a conventional engine company is with the proposal for LAPCAT and the 2STO proposal from the USAF.]

Er, no. In many cases this is so but strangely enough when engine manufacturers are going out to push the envelope or try and market a 'new' engine that was not a straight out development of an existing engine they quite often put them on notional or concept vehicles for marketing purposes. Aerojet did it for the RSX, Marquardt did it for their LH2 powered Supercharged-Ejection Ram Jet engine and did a much more detailed design or their H2O2/JP4 engine. Usually how detailed they get is how interested they are in selling the design, especially for a "non-standard" engine concept.

And yet what you say engine companies never do is exactly what LarsJ was requiring REL to do. Granted he back-tracked later but that is essentially what he said and I was pointing out that's not the way it works so in that we agree it seems :)

The problem is the more narrow the market, (and obviously the more speculative it is) the more the engine manufacturer has to detail and define the engine and it's capabilities to a prospective client or investor. That's what Skylon is. It's a design of a vehicle powered by SABRE engines that can, with assumed performance of the SABRE, go from a runway into orbit and back. Is it the "set-in-stone" design for Skylon? Not at all and REL has admitted that fact as they are not airframe designers but engine manufacturers. Still there ARE certain well known rules and assumptions for concepts that in general perform the way Skylon is supposed to perform and under those Skylon is a "practical" design at the current level of TRL.

If Skylon is built to exactly the specifications done so far by REL I'd be highly surprised, but I would not be surprised at all if an operational Skylon looked almost exactly like what REL has laid out as it's a very conservative design with the assumptions given.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 08/08/2016 08:27 PM
Thank God for China, rescuing this thread from whining about SpaceX:

Looks like they're developing their own version of Skylon.

Quote
It will rely on an indigenous turbine, ramjet, and rocket engines to power the spaceplane in various phases of flight.

Sounds like a multi-engine approach, rather than a single hybrid engine.

If they can make the design close with the mass penalty of three sets of engines, I will be very surprised.

I think that's the way it was written/understood but I don't see anything that would indicate it's not a composite engine of some type. "Turbo-Ram-Rocket" is not that hard to do IF you can master the materials and manufacturing for that matter a SERJ type engine was demonstrated with late 50s early 60s manufacturing and technology and China has that.

Of course the devil is in the details and while I think the presentation probably ripped-off Skylon graphics I'm not surprised a basic similarity would appear. (After all the "original" came from Kelly Johnson to address most of the same issues for high supersonic flight :) ) At least they didn't use a NASP image and there appears to be no cockpit and passenger window running down the sides like most rip-offs :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Paul451 on 08/08/2016 10:10 PM
AJ/RD/GE/etc don't propose aircraft. They are catering to an existing market. They anticipate that aircraft developers will keep developing newer models and will go looking for engines to power those models, so they try to push the technology further in the direction they think that market is going (more power, better fuel economy, lower maintenance costs) and sometimes they pick correctly and are selected, and sometimes they fail and have to scramble to catch up. But the basic aircraft design is never the engine manufacturer's. Not in large airliners, not in supersonic fighters, not cargo planes, not rocket launchers, not missiles.
Skylon is REL's design. Solely and utterly. Even moreso, it's mainly Bond's design.
There is no "market" of Skylon-type vehicle developers that is going to go looking for a suitable engine to power their future designs. Skylon is REL, REL is Skylon.
There's no comparison with engine companies. Hence this continual reference to conventional aircraft development makes no sense.
Er, no. In many cases this is so but strangely enough when engine manufacturers are going out to push the envelope or try and market a 'new' engine that was not a straight out development of an existing engine they quite often put them on notional or concept vehicles for marketing purposes. Aerojet did it for the RSX, Marquardt did it for their LH2 powered Supercharged-Ejection Ram Jet engine and did a much more detailed design or their H2O2/JP4 engine. Usually how detailed they get is how interested they are in selling the design, especially for a "non-standard" engine concept.

So just to be clear, you're comparing REL's development model with companies which never actually sold their product?

Do you have a successful comparison?

[edit: Although it's interesting that in order to get even close, you had to go to VTO-boosters, even though the original analogy was the REL is acting like an aircraft-engine company.]
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: CameronD on 08/08/2016 11:32 PM
So just to be clear, you're comparing REL's development model with companies which never actually sold their product?

Do you have a successful comparison?

[edit: Although it's interesting that in order to get even close, you had to go to VTO-boosters, even though the original analogy was the REL is acting like an aircraft-engine company.]

REL can't possibly act like an aircraft-engine company... they've never built one.  ;D

Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: knowles2 on 08/09/2016 12:21 AM
Thank God for China, rescuing this thread from whining about SpaceX:

Looks like they're developing their own version of Skylon.

And good for them, as Europe is too timid to fully fund such a huge sum for the full-up space plane and Reaction Engines refuses to come up with a more practical, gradual plan to develop a reusable orbital vehicle.
http://www.spaceflightinsider.com/organizations/china-national-space-administration/china-develop-hybrid-spaceplane-cheaper-space-travel/
From a nation that has trouble developing it own indigenous jet engines, we shall see but I won't be placing my money on seeing this take off.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 08/09/2016 12:32 AM
Thank God for China, rescuing this thread from whining about SpaceX:

Looks like they're developing their own version of Skylon.

And good for them, as Europe is too timid to fully fund such a huge sum for the full-up space plane and Reaction Engines refuses to come up with a more practical, gradual plan to develop a reusable orbital vehicle.
http://www.spaceflightinsider.com/organizations/china-national-space-administration/china-develop-hybrid-spaceplane-cheaper-space-travel/
From a nation that has trouble developing it own indigenous jet engines, we shall see but I won't be placing my money on seeing this take off.
Sir Frank Whittle just rolled over...
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Lars-J on 08/09/2016 12:51 AM
I sympathize with your frustration, because it is such an a**-backwards business plan. (if accurate) If they have any interest in bringing Skylon to reality, REL needs to LEAD this consortium, not hope that someone else will do it. They need to become the prime contractor.

Because Aerojet, Rocketdyne, GE, Rolls-Royce, and Pratt and Whitney have shown that engine manufacturers always have to be the "prime contractor" and take the LEAD in designing and building the vehicles their engines power... :)

They do have to if they hope to have any input in the design of the vehicle. Imagine SpaceX just building the Merlin 1D, and then only selling it if someone would build a Falcon 9 with it. Or an elevator builder selling blueprints for a skyscraper that someone needs to build for them. THAT is the backward part.

Nobody would bat an eye if REL was selling a neat engine that had its use for an air breathing vehicle. But instead they are trying to sell... Skylon.

But note what YOU said:
"I sympathize with your frustration, because it is such an a**-backwards business plan. (if accurate) If they have any interest in bringing Skylon to reality, REL needs to LEAD this consortium, not hope that someone else will do it. They need to become the prime contractor."

Doesn't seem that way to me as they've always said that Skylon is what they put together to answer questions on capability if fitted with SABRE rather than a "required" design. Further they have admitted, though it's a less than optimum design choice, that a TSTO based on SABRE is possible. The main question isn't about Skylon but about SABRE since it is what the entire concept hinges on.

So no, what you said above and what you said previously have nothing to do with each other as you ORIGINAL complaint was that "engine manufacturer" has to LEAD the design/construction consortium, not provide "input" into the design, on order to bring the design to fruition. You then follow with complaining that the "engine manufacturer" is in fact doing, (but isn't clearly) exactly what you demand they do?

I don't see why you have a hard time understanding my position, or think that my two statements contradict each other. If REL just wants to build and sell SABRE, they could find great success (or failure) just like many other engine manufacturers. But if they want specifically SKYLON built, then they need to take control and become the prime contractor selling it to customers.

This unwillingness to start and lead the "consortium" needed to get Skylon built is why I (and many others) for a long time assumed that REL simply wasn't interested in seeing it be built, that REL simply wanted to live off government research funding where they didn't have to produce much of anything. I've changed my mind on this - mostly - But it still appears that REL lacks that final killer instinct to make Skylon happen, by any means necessary.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: hkultala on 08/09/2016 09:10 AM
Thank God for China, rescuing this thread from whining about SpaceX:

Looks like they're developing their own version of Skylon.

And good for them, as Europe is too timid to fully fund such a huge sum for the full-up space plane and Reaction Engines refuses to come up with a more practical, gradual plan to develop a reusable orbital vehicle.

What's more practical in having three sets of heavy engines instead of one set of engines?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/09/2016 09:55 AM
Thank God for China, rescuing this thread from whining about SpaceX:

Looks like they're developing their own version of Skylon.

And good for them, as Europe is too timid to fully fund such a huge sum for the full-up space plane and Reaction Engines refuses to come up with a more practical, gradual plan to develop a reusable orbital vehicle.
http://www.spaceflightinsider.com/organizations/china-national-space-administration/china-develop-hybrid-spaceplane-cheaper-space-travel/
From a nation that has trouble developing it own indigenous jet engines, we shall see but I won't be placing my money on seeing this take off.
That could have been said of America, which did not have an indigenous jet engine development programme before the British brought a sample to them.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 08/09/2016 01:37 PM
Thank God for China, rescuing this thread from whining about SpaceX:

Looks like they're developing their own version of Skylon.

And good for them, as Europe is too timid to fully fund such a huge sum for the full-up space plane and Reaction Engines refuses to come up with a more practical, gradual plan to develop a reusable orbital vehicle.
http://www.spaceflightinsider.com/organizations/china-national-space-administration/china-develop-hybrid-spaceplane-cheaper-space-travel/
From a nation that has trouble developing it own indigenous jet engines, we shall see but I won't be placing my money on seeing this take off.
That could have been said of America, which did not have an indigenous jet engine development programme before the British brought a sample to them.
:)
https://www.youtube.com/watch?v=pDHtkm2vW_Y
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Paul451 on 08/09/2016 02:25 PM
Do you have a successful comparison?
OK, how about Heinkel? They designed the Heinkel He 178 around the Heinkel HeS 3,

Heinkel was an aircraft company. So again the analogy doesn't work with REL.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Robotbeat on 08/09/2016 02:57 PM
Thank God for China, rescuing this thread from whining about SpaceX:

Looks like they're developing their own version of Skylon.

And good for them, as Europe is too timid to fully fund such a huge sum for the full-up space plane and Reaction Engines refuses to come up with a more practical, gradual plan to develop a reusable orbital vehicle.

What's more practical in having three sets of heavy engines instead of one set of engines?
Actually starting to build something that might fly instead of Powerpoints forever. (Something which has little to do with the number of engines.)
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 08/09/2016 03:26 PM
IMHO I consider REL a research project consortium...
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Paul451 on 08/09/2016 04:47 PM
OK, the Wright Brothers. They designed and carved their own propellers, and had their mechanic build an engine in their workshop?
Or were they a glider company first?

I think you might have lost track of the argument.

But in some ways claiming REL are an engine manufacturer is flawed.

That's not the argument. I was responding to the claim that what REL is doing is normal in the aircraft/aerospace industry, "Rolls Royce doesn't build airframes, they leave that to aircraft manufacturers". The development model REL wants for Skylon is nothing like the development model of aircraft or launchers.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: hkultala on 08/09/2016 05:17 PM
Thank God for China, rescuing this thread from whining about SpaceX:

Looks like they're developing their own version of Skylon.

And good for them, as Europe is too timid to fully fund such a huge sum for the full-up space plane and Reaction Engines refuses to come up with a more practical, gradual plan to develop a reusable orbital vehicle.

What's more practical in having three sets of heavy engines instead of one set of engines?
Actually starting to build something that might fly instead of Powerpoints forever. (Something which has little to do with the number of engines.)

Alan Bond has already been designing something that actually flies(Blue Streak),
wasting money just to create "something that might fly" makes no sense if that "something that flies" does not do anything usable and has no technology that the final craft is going to use.

And for Skylon, they have built the preocooler which is the most important part of the craft.

Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Jim on 08/09/2016 06:11 PM

What is the development model of aircraft or launchers? - launchers seems to vary from the zero-interaction of ULA bolting stockpiled Russian engines to their rockets through to SpaceX's agile development.


You are wrong on both examples.

The Merlin was developed for the Falcon 1 originally.

ULA didn't exist when the RD-180 was developed.   RD-180 was specifically developed for Atlas.  GD/LM participated in its development just like any other new rocket engine.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Paul451 on 08/09/2016 06:56 PM

I suggest you go back and read the comments I was replying to.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/09/2016 08:43 PM
:)
https://www.youtube.com/watch?v=pDHtkm2vW_Y
Perhaps you should look a little deeper into its history

https://en.wikipedia.org/wiki/Bell_P-59_Airacomet

The engine is a copy of the Power Jets W2B/23

AFAIK the US had no indigenous jet engine projects anywhere close to flight weight when they were informed the Gloster existed.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 08/09/2016 09:54 PM
:)
https://www.youtube.com/watch?v=pDHtkm2vW_Y
Perhaps you should look a little deeper into its history

https://en.wikipedia.org/wiki/Bell_P-59_Airacomet

The engine is a copy of the Power Jets W2B/23

AFAIK the US had no indigenous jet engine projects anywhere close to flight weight when they were informed the Gloster existed.
John, I guess we are two nations separated by a common language as we are in full agreement once again! ;) ;D
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: CameronD on 08/10/2016 12:25 AM
What's more practical in having three sets of heavy engines instead of one set of engines?
Actually starting to build something that might fly instead of Powerpoints forever. (Something which has little to do with the number of engines.)

On that basis, perhaps REL do indeed have a perfect design??  After all, there can't possibly be anything wrong with a design that only exists on Powerpoint.. and if you do just happen you notice something screwy (perhaps a design parameter or three), it takes only a minute or two to edit it.  Science Fiction folks do this all the time. ::)
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: knowles2 on 08/10/2016 12:29 AM
Thank God for China, rescuing this thread from whining about SpaceX:

Looks like they're developing their own version of Skylon.

And good for them, as Europe is too timid to fully fund such a huge sum for the full-up space plane and Reaction Engines refuses to come up with a more practical, gradual plan to develop a reusable orbital vehicle.
http://www.spaceflightinsider.com/organizations/china-national-space-administration/china-develop-hybrid-spaceplane-cheaper-space-travel/
From a nation that has trouble developing it own indigenous jet engines, we shall see but I won't be placing my money on seeing this take off.
That could have been said of America, which did not have an indigenous jet engine development programme before the British brought a sample to them.
But even with many many samples  of Russian engines, China is still behind The West and Russia in jet engine developments and being able to research, design and build it own engines completely from scratch.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/10/2016 06:33 AM
Quote
What's more practical in having three sets of heavy engines instead of one set of engines?
Actually starting to build something that might fly instead of Powerpoints forever. (Something which has little to do with the number of engines.)
For a proper "Powerpoint Project"  No hardware is built

REL have built quite a lot of hardware up to the pre cooler and precooler test system, contra rotating turbines and assorted nozzle test rocket engines and heat exchangers in various technologies.

Perhaps you might like to check some of the roundup slides on their presentations?

On that basis, perhaps REL do indeed have a perfect design??  After all, there can't possibly be anything wrong with a design that only exists on Powerpoint.. and if you do just happen you notice something screwy (perhaps a design parameter or three), it takes only a minute or two to edit it.  Science Fiction folks do this all the time. ::)
The difference is that when REL get funding they make stuff and do things, not issue another video about it.

Nor have they issued a video and then announced "Oh we can't do this but the next version will work" either.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 08/10/2016 07:52 PM
I try not to scoff at people that try to break new ground. History has taught us that many pathfinders were laughed at from the Wrights to Goddard and now we laud their efforts. The road of aerospace projects is riddled with forgotten individuals who sweated blood and tears and have been forgotten except for by a few.  PowerPoint comments are best reserved for wasteful government agencies that have promised a lot and delivered little to the taxpayers. Individuals that take on an aerospace project should be commend for their efforts and be allowed to prove their concept with a healthy dose of skepticism by the observers. Many X programs that might be viewed as a failures in terms of not meeting the original objectives, have still provided valuable research data increasing the knowledge base.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/10/2016 08:04 PM
PowerPoint comments are best reserved for wasteful government agencies that have promised a lot and delivered little to the taxpayers.
Or in the case of the X30 and X33 delivered nothing at a total cost of $2Bn+
Quote
Individuals that take on an aerospace project should be commend for their efforts and be allowed to prove their concept with a healthy dose of skepticism by the observers.
Whenever REL have had the funds they have proved their assertions. And there have never  been too few sceptics (often with very little awareness of the subject they are talking about) to tell them they can't do it.  :(
Quote
Many X programs that might be viewed as a failures in terms of not meeting the original objectives, have still provided valuable research data increasing the knowledge base.
Actually that's exactly the objective of properly conducted X programmes. To fill in the design equations and charts of engineering handbooks.  It's only when they are meant to act as prototypes for operational vehicles that things usually ended badly.  :(
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Robotbeat on 08/10/2016 08:54 PM
PowerPoint comments are best reserved for wasteful government agencies that have promised a lot and delivered little to the taxpayers.
Or in the case of the X30 and X33 delivered nothing at a total cost of $2Bn+...
...delivered a lot more than Reaction Engines so far. Fabricated tanks (which had problems, but still). Even test-fired the linear aerospike. If that's your standard of "nothing," than Reaction Engines has delivered much less than nothing. Though luckily for not as much money as for X-33.

I'm not opposed to RE or Skylon, but they just don't seem to have a fire in their belly, a willingness to find a "minimum viable product" that can be built upon now without waiting decades to find someone desperate enough to sink enormous funds without any flying precursor.

It's as if SpaceX were founded, but refused to do anything but subcomponent tests of Raptor. Never flying Falcon 1, 9, cargo or crew or Heavy but just holding out hope that a few guys in California knew enough about rocketry to be worth sinking billions into for a totally unproven concept.

Now I don't know if the Chinese are serious or not. Time will tell. But at least there's a hope of something really actually flying.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 08/10/2016 09:19 PM
AJ/RD/GE/etc don't propose aircraft. They are catering to an existing market. They anticipate that aircraft developers will keep developing newer models and will go looking for engines to power those models, so they try to push the technology further in the direction they think that market is going (more power, better fuel economy, lower maintenance costs) and sometimes they pick correctly and are selected, and sometimes they fail and have to scramble to catch up. But the basic aircraft design is never the engine manufacturer's. Not in large airliners, not in supersonic fighters, not cargo planes, not rocket launchers, not missiles.
Skylon is REL's design. Solely and utterly. Even moreso, it's mainly Bond's design.
There is no "market" of Skylon-type vehicle developers that is going to go looking for a suitable engine to power their future designs. Skylon is REL, REL is Skylon.
There's no comparison with engine companies. Hence this continual reference to conventional aircraft development makes no sense.
Er, no. In many cases this is so but strangely enough when engine manufacturers are going out to push the envelope or try and market a 'new' engine that was not a straight out development of an existing engine they quite often put them on notional or concept vehicles for marketing purposes. Aerojet did it for the RSX, Marquardt did it for their LH2 powered Supercharged-Ejection Ram Jet engine and did a much more detailed design or their H2O2/JP4 engine. Usually how detailed they get is how interested they are in selling the design, especially for a "non-standard" engine concept.

So just to be clear, you're comparing REL's development model with companies which never actually sold their product?

Do you have a successful comparison?

So we're clear you DO know who Marquardt was, right? (https://en.wikipedia.org/wiki/Marquardt_Corporation) You know the folks who built and sold THOUSANDS of different models of wind-tunnels, pulsejets, ramjets and rocket systems to every major manufacturer and military service in the US?

My comparison is that EVERY engine manufacturer occasionally goes out on a limb and more often than not they make changes to the market/industry. REL is starting OUT with a non-standard engine that address what people have considered "problems" with air-breathing launch and they are not the first to do so by any means.

Quote
[edit: Although it's interesting that in order to get even close, you had to go to VTO-boosters, even though the original analogy was the REL is acting like an aircraft-engine company.]

I didn't HAVE to bring up "VTO-boosters" to get close, specifically I brought up the SERJ because it is pretty close to what REL wants to get out of the SABRE. Lars-J brought up the Merlin, after I'd listed both air-breathing and rocket engine makers in effect working with airframe makers to bring product to market NOT running the show. The reason for bringing up rocket engine makers is, rather obviously, because rockets are involved not because they are the only thing that comes 'close' to any performance parameters.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 08/10/2016 10:02 PM
I don't see why you have a hard time understanding my position, or think that my two statements contradict each other. If REL just wants to build and sell SABRE, they could find great success (or failure) just like many other engine manufacturers. But if they want specifically SKYLON built, then they need to take control and become the prime contractor selling it to customers.

This unwillingness to start and lead the "consortium" needed to get Skylon built is why I (and many others) for a long time assumed that REL simply wasn't interested in seeing it be built, that REL simply wanted to live off government research funding where they didn't have to produce much of anything. I've changed my mind on this - mostly - But it still appears that REL lacks that final killer instinct to make Skylon happen, by any means necessary.

I'm not having a hard time understanding your position, what's hard is trying to wrap my mind around why you think the two statements are NOT contradictory since you admit they are based on a your bias' and assumptions rather than actual business practice or history :)

Lets review: REL has always been attempting to sell the SABRE concept as a viable combined cycle engine for earth-to-orbit flight. In general there is and always has been a significant bias towards the assumption that any type of air-breathing engine was impractical for such operations and on top of this the principles had a very visible previously 'failed' project using a similar engine concept who's issues needed to be addressed in order to allow a focus on the engine cycle not the failed LV proposal. In addition people were questioning not only the engine cycle itself but the overall ability of any LV to reach orbit with any payload, specifically because REL was stating it could be done in a single-stage, air breathing vehicle.

So in order to address all the above REL spent time outlining and defining a notional vehicle that, using the SABRE could perform as they suggested with the performance they assumed could be derived from the SABRE in a conservative overall design. Hence Skylon. Every use of the Skylon in PR, media and written works has highlighted the performance and possibility of the SABRE specifically and the Skylon only generally. Specific enough to showcase the possibilities of the SABER but not enough to constitute a fully designed and ready to build vehicle.

This is on purpose. Yet as you note you and many others made the assumption that REL was specifically trying to get the Skylon built but as they have consistently said they are aiming at building the SABRE and Skylon is only there to provide a platform for that purpose. Skylon COULD provide the basis for SABRE powered SSTO vehicle it has been shown that as a basic concept and given close approximations of the assumed performance of the SABRE engine it would actually work which is the basic point of the whole exercise by REL.

The other false assumption is that REL could simply "sell" it's engine to a customer when it's very clear that, (and I've already noted that) in general there are no "makers" of air-breathing LVs out there to sell to. This isn't because it is known and proven that an air breathing launch vehicle isn't possible. In fact almost every major airframe maker at some point HAS done preliminary design work and (sometimes very detailed) studies into building such vehicles for almost 50 years and the consensus has always been they are quite possible with the right propulsion system.

But there's a couple of catches; First REL has to prove the engine performance. Second there are some design constraints that make the SABRE 'different' to use for an LV propulsion system that most past designs have not taken into consideration. Again, that's what Skylon is for in showing how those differences effect the airframe design and suggesting solutions or methods of addressing those effects. Simple.

The disconnect is that you had an erroneous original conclusion that while you have modified you still hold. REL never intended to sell Skylon, though thanks to the work done by REL it actually might be the basis of the real Skylon LV. But once SABRE is proven its quite possible that whomever they partner with on actual development of "Skylon" will toss all of RELs work in favor of their own design. More likely they will fold REL's Skylon into their own work and proceed from there. Much more likely is that once SABRE is proven REL will in fact have 'customers' looking to buy their SABRE's for their own designs but I wouldn't be that surprised to see the work done on Skylon itself to be included in those designs. SSTO, TSTO, whatever as already note the work REL has done IS applicable even if it's not strictly the current REL "design" of Skylon.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 08/10/2016 10:08 PM
Thank God for China, rescuing this thread from whining about SpaceX:

Looks like they're developing their own version of Skylon.

And good for them, as Europe is too timid to fully fund such a huge sum for the full-up space plane and Reaction Engines refuses to come up with a more practical, gradual plan to develop a reusable orbital vehicle.

What's more practical in having three sets of heavy engines instead of one set of engines?

Three engine TYPES does not equate to three actual engines as I noted. The only thing different in a general description of the SABRE and what was printed is the inclusion of a ramjet and how often have we seen the SABRE described in print WITH one? (Or worse adding SCramjets? :) )

Thank God for China, rescuing this thread from whining about SpaceX:

Looks like they're developing their own version of Skylon.

And good for them, as Europe is too timid to fully fund such a huge sum for the full-up space plane and Reaction Engines refuses to come up with a more practical, gradual plan to develop a reusable orbital vehicle.
http://www.spaceflightinsider.com/organizations/china-national-space-administration/china-develop-hybrid-spaceplane-cheaper-space-travel/
From a nation that has trouble developing it own indigenous jet engines, we shall see but I won't be placing my money on seeing this take off.
That could have been said of America, which did not have an indigenous jet engine development programme before the British brought a sample to them.

Lockheed L-1000 was in development already before we saw a British jet. (http://www.tailsthroughtime.com/2010/06/probably-one-of-most-obscure-yet.html) Wasn't as good and was eventually developed into a more standard jet engine but it was on-going already.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: knowles2 on 08/10/2016 10:12 PM
PowerPoint comments are best reserved for wasteful government agencies that have promised a lot and delivered little to the taxpayers.
Or in the case of the X30 and X33 delivered nothing at a total cost of $2Bn+...
...delivered a lot more than Reaction Engines so far. Fabricated tanks (which had problems, but still). Even test-fired the linear aerospike. If that's your standard of "nothing," than Reaction Engines has delivered much less than nothing. Though luckily for not as much money as for X-33.

Quote
I'm not opposed to RE or Skylon, but they just don't seem to have a fire in their belly, a willingness to find a "minimum viable product" that can be built upon now
It's as if SpaceX were founded, but refused to do anything but subcomponent tests of Raptor. Never flying Falcon 1, 9, cargo or crew or Heavy but just holding out hope that a few guys in California knew enough about rocketry to be worth sinking billions into for a totally unproven concept.
[/quote]

The difference here is that Reaction engines haven't got any billionaires on hand who is willing to stump up the money for the project, let alone one willing to go bankrupt to get Sabre and Skylon flying, they have been living on scraps of research grants for years.

I have no doubt in my mind if Reaction engines had someone willing to sink half a billion a quid into the company they would have at least ended up with an engine that works and was ready to fly and perhaps a prototype vehicle using the engines to fly. They have already aired ideas for smaller vehicles that would test the engines. But Skylon is pretty much the minimum viable product that is capable of launching satellites into space or doing anything useful up there. Anything smaller and you lose a lot capabilities, why not reducing costs all that much. 

Musk took all of the early risks of Space X on himself, building the engine and Falcon 1, he then convince his friends , a lot of them billionaires and millionaires to fund Falcon 9 launch.

Personally I'm still surprise they are quoting 12bn pounds for Skylon, which seems to me way overpriced. I think it may well be worth their time and effort to recalculate that cost using Space X approach.

I suspect RE had two billion quid they would have gotten a working engine and least a prototype vehicle fly of some sort flying at least to sub orbital or even orbital, an the manufacturing facility ready to build a larger, more capable vehicles.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 08/10/2016 10:24 PM
PowerPoint comments are best reserved for wasteful government agencies that have promised a lot and delivered little to the taxpayers.
Or in the case of the X30 and X33 delivered nothing at a total cost of $2Bn+...
...delivered a lot more than Reaction Engines so far. Fabricated tanks (which had problems, but still). Even test-fired the linear aerospike. If that's your standard of "nothing," than Reaction Engines has delivered much less than nothing. Though luckily for not as much money as for X-33.

I'm not opposed to RE or Skylon, but they just don't seem to have a fire in their belly, a willingness to find a "minimum viable product" that can be built upon now without waiting decades to find someone desperate enough to sink enormous funds without any flying precursor.

It's as if SpaceX were founded, but refused to do anything but subcomponent tests of Raptor. Never flying Falcon 1, 9, cargo or crew or Heavy but just holding out hope that a few guys in California knew enough about rocketry to be worth sinking billions into for a totally unproven concept.

Now I don't know if the Chinese are serious or not. Time will tell. But at least there's a hope of something really actually flying.
Absolutely, we got more bang for the X-33, from rocket engine to cryopumping issues and composite tank data. Of course the agency PowerPoint program I had in mind was  the 9B NASA Constellation; however we did get a tower and a really neat large scale model rocket launch... :)
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Paul451 on 08/10/2016 11:22 PM
Yet as you note you and many others made the assumption that REL was specifically trying to get the Skylon built but as they have consistently said they are aiming at building the SABRE and Skylon is only there to provide a platform for that purpose.

Perhaps because every time someone suggested an alternative (especially TSTO), they were jumped over by the true-believers who insisted that Skylon was the one-true-design, perfect in every way, and anything else was madness and ignorance.

I mean, where have you been for the last 5 threads?

Do you have a successful comparison?
So we're clear you DO know who Marquardt was, right?

Bankrupt.

and a really neat large scale model rocket launch...

It's amazing how big you can make fireworks.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 08/10/2016 11:36 PM
Yet as you note you and many others made the assumption that REL was specifically trying to get the Skylon built but as they have consistently said they are aiming at building the SABRE and Skylon is only there to provide a platform for that purpose.

Perhaps because every time someone suggested an alternative (especially TSTO), they were jumped over by the true-believers who insisted that Skylon was the one-true-design, perfect in every way, and anything else was madness and ignorance.

I mean, where have you been for the last 5 threads?

Do you have a successful comparison?
So we're clear you DO know who Marquardt was, right?

Bankrupt.

and a really neat large scale model rocket launch...

It's amazing how big you can make fireworks.
All you need is " We the people's" money... ;)
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/11/2016 06:37 AM
...delivered a lot more than Reaction Engines so far. Fabricated tanks (which had problems, but still). Even test-fired the linear aerospike. If that's your standard of "nothing," than Reaction Engines has delivered much less than nothing. Though luckily for not as much money as for X-33.

I'm not opposed to RE or Skylon, but they just don't seem to have a fire in their belly, a willingness to find a "minimum viable product" that can be built upon now without waiting decades to find someone desperate enough to sink enormous funds without any flying precursor.

It's as if SpaceX were founded, but refused to do anything but subcomponent tests of Raptor. Never flying Falcon 1, 9, cargo or crew or Heavy but just holding out hope that a few guys in California knew enough about rocketry to be worth sinking billions into for a totally unproven concept.

Now I don't know if the Chinese are serious or not. Time will tell. But at least there's a hope of something really actually flying.
Absolutely, we got more bang for the X-33, from rocket engine to cryopumping issues and composite tank data. Of course the agency PowerPoint program I had in mind was  the 9B NASA Constellation; however we did get a tower and a really neat large scale model rocket launch... :)
None of which was essential to meeting the only core requirement of the X33 programme which was demonstrate SSTO or near SSTO performance of a vehicle. BTW X33 was a 1$Bn programme and that was expected to deliver a complete flight vehicle on that budget. LM sucked down the whole budget and delivered nothing close to a flight vehicle.

REL identified designing and making the pre-cooler as the unknown element in the SABRE design so that's what they went for. 

That's what you do when your goal is to make something work, not suck up as much government money as possible to ensure your core ELV business is protected.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/11/2016 06:51 AM
Perhaps because every time someone suggested an alternative (especially TSTO), they were jumped over by the true-believers who insisted that Skylon was the one-true-design, perfect in every way, and anything else was madness and ignorance.
SABRE is an engine designed to accelerate a vehicle from runway to orbit. It is also designed to be testable on the ground. Either it will meet those performance specs or it does not, before you have to install it in a vehicle and fly it.

Either you want an engine that can go from runway to orbit or you do not.

If you want runway to orbit you need a SABRE cycle. If you do not then whatever it is is not a SABRE cycle. REL are probably the lead developers on those as well with the Scimitar. Call it whatever you want, but it's not a SABRE.

If you've got a fully orbital capable engine not to build an SSTO round it only makes sense if you're too scared to do the design. Given REL have spent some time and effort on doing such a reference design for you it would an epic failure of nerve not to.  :(

It's just a series of logical questions.  It's a question of what a prospective customer wants and do they understand what they are getting. Saying you want TSTSO and SABRE is simply illogical.

I'm quite sure there is plenty about Skylon that has deliberately been left low resolution so the vehicle consortium can impose their own mark on the design but I also expect it would take a lot of effort to come up with a design that looked radically different that can do the job as well as Skylon is expected to.

Once you understand the massive CoG and CoL shifts during the M0-M23-M0 flight path and you want an easily controlled vehicle the Skylon configuration is tough to beat.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 08/11/2016 01:28 PM
...delivered a lot more than Reaction Engines so far. Fabricated tanks (which had problems, but still). Even test-fired the linear aerospike. If that's your standard of "nothing," than Reaction Engines has delivered much less than nothing. Though luckily for not as much money as for X-33.

I'm not opposed to RE or Skylon, but they just don't seem to have a fire in their belly, a willingness to find a "minimum viable product" that can be built upon now without waiting decades to find someone desperate enough to sink enormous funds without any flying precursor.

It's as if SpaceX were founded, but refused to do anything but subcomponent tests of Raptor. Never flying Falcon 1, 9, cargo or crew or Heavy but just holding out hope that a few guys in California knew enough about rocketry to be worth sinking billions into for a totally unproven concept.

Now I don't know if the Chinese are serious or not. Time will tell. But at least there's a hope of something really actually flying.
Absolutely, we got more bang for the X-33, from rocket engine to cryopumping issues and composite tank data. Of course the agency PowerPoint program I had in mind was  the 9B NASA Constellation; however we did get a tower and a really neat large scale model rocket launch... :)
None of which was essential to meeting the only core requirement of the X33 programme which was demonstrate SSTO or near SSTO performance of a vehicle. BTW X33 was a 1$Bn programme and that was expected to deliver a complete flight vehicle on that budget. LM sucked down the whole budget and delivered nothing close to a flight vehicle.

REL identified designing and making the pre-cooler as the unknown element in the SABRE design so that's what they went for. 

That's what you do when your goal is to make something work, not suck up as much government money as possible to ensure your core ELV business is protected.
I would have loved to have seen that 9B spent on SKYLON on a joint R&D program between the air forces of both US and the UK...
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Hanelyp on 08/11/2016 03:28 PM
I have to agree with Paul that using a Sabre cycle engine for the first stage of a 2STO launcher is not a stupid idea.  Sabre is designed to deliver SSTO performance, but that does not eliminate using the engine on a booster stage as a viable concept.  A launcher that can cruise to "launch" point, shotput to altitude at hypersonic speed, and the booster then cruise back to a runway, has some operational advantages.  Like all rocket launchers, staging tends to improve the payload/GTO ratio, though that's not the best metric for a design's economics.  Vs. a rocket booster return to start point is easier.  Whether the economic case closes for SSTO or 2STO launchers based on the engine is harder to see from where I stand.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Lars-J on 08/11/2016 04:51 PM
I have to agree with Paul that using a Sabre cycle engine for the first stage of a 2STO launcher is not a stupid idea.  Sabre is designed to deliver SSTO performance, but that does not eliminate using the engine on a booster stage as a viable concept.  A launcher that can cruise to "launch" point, shotput to altitude at hypersonic speed, and the booster then cruise back to a runway, has some operational advantages.  Like all rocket launchers, staging tends to improve the payload/GTO ratio, though that's not the best metric for a design's economics.  Vs. a rocket booster return to start point is easier.  Whether the economic case closes for SSTO or 2STO launchers based on the engine is harder to see from where I stand.

Exactly. What makes SABRE unique is the air breathing phase. Once you are above the atmosphere (or cease collecting O2), then it is no different than a normal rocket engine. And that is where staging - if one wanted to do it - would make sense.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 08/11/2016 05:25 PM
Yet as you note you and many others made the assumption that REL was specifically trying to get the Skylon built but as they have consistently said they are aiming at building the SABRE and Skylon is only there to provide a platform for that purpose.

Perhaps because every time someone suggested an alternative (especially TSTO), they were jumped over by the true-believers who insisted that Skylon was the one-true-design, perfect in every way, and anything else was madness and ignorance.

I mean, where have you been for the last 5 threads?

Here :) Arguing that while it's "non-optimum" it's not only a consideration but, (and I've said this consistently) that the Skylon design itself while it is technically an SSTO vehicle is specifically a TSTD (Two-Stage-To-Destination) design as it's based on the idea of equaling EELV satellite delivery capability. That requires delivery to GTO and Skylon can't do it alone so needs a stage/transfer-vehicle/what-have-you.

Do you have a successful comparison?
So we're clear you DO know who Marquardt was, right?

Bankrupt.[/quote]

After being quite lucrative over decades and it actually still exists IIRC so my point stands.

SABRE is an engine designed to accelerate a vehicle from runway to orbit. It is also designed to be testable on the ground. Either it will meet those performance specs or it does not, before you have to install it in a vehicle and fly it.

Either you want an engine that can go from runway to orbit or you do not.

Rather simplistic actually. It keeps being said that if you want an engine for a TSTO you want the Scimitar and not the SABRE because of the mistaken belief that "if you want to go to orbit need SABRE, if you're not going all the way you don't" which is, pardon me BS.

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If you want runway to orbit you need a SABRE cycle. If you do not then whatever it is is not a SABRE cycle. REL are probably the lead developers on those as well with the Scimitar. Call it whatever you want, but it's not a SABRE.

SABRE isn't a single niche engine no matter what people think though that's what REL WANTS the simple and very obvious truth is it's not that limited of an engine cycle. SABRE is capable of air-breathing up to around Mach-5 pretty easily followed by rocket powered flight, technically up to orbital speed but that should be noted that includes every Mach number short of that speed as well. Note the main difference between SABRE and Scimitar is the latter is designed for extended CRUISE at hypersonic speed while the former is designed as an acceleration engine.

"Runway-to-Orbit" is NOT about the engine, as I've often pointed out the SERJ and several other combined cycle engine system are perfectly capable of performing the same mission and have been since the mid-50s. The major problem is they almost all got caught in the two main traps of thinking at the time, (and currently if we are being honest) liquid-air-cycle and SCramjets as "requirements" for operation. "Runway-to-Mach-10-and-500,000ft" would be something that SABRE could and would do as well as orbital flight so trying to say a SABRE is ONLY good for runway-to-orbit and nothing else is simply a bias on the part of the person saying it. :)

There's optimum and then there's good-enough either of which SABRE is perfectly capable of handling and still being SABRE.

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If you've got a fully orbital capable engine not to build an SSTO round it only makes sense if you're too scared to do the design. Given REL have spent some time and effort on doing such a reference design for you it would an epic failure of nerve not to.  :(

That statement actually hurts my brain because it points up a lot of misunderstandings about what REL has done, what they are proposing, and what their goals are. In reverse order; TSTOs have proven advantages over SSTO designs when directly compared and vice-versa so the 'call' to go one way or the other is a business, engineering, and operations decision. Not something you base on optimum use of a specific engine design. RELs "efforts" have amounted to what would be a very preliminary study of a possible airframe that can maybe do "this" with an assumed performance of "this" from the propulsion system. REL has gone a bit further due to being biased towards an SSTO design but because they are not in fact airframe designers/makers they have missed some obvious areas. Any actual airframe designer/engineer/maker is going to take the "Skylon" design under consideration and then do actual trade studies to define a REAL design capable of doing what the overall business/market/user requires.

The REL "Skylon" has a leg up in the preliminaries because of the work REL has done but they didn't do the work to actually DESIGN an airframe, they did the work to define something that by using SABRE engines that meet expectations could do "this" operationally. Someone who's going to make an actual Skylon vehicle will do a lot more detailed and in-depth work which may or may not validate RELs assumptions and combine that with marketing and operational inputs which may not in fact recommend an SSTO design at this time or a different airframe configuration.

Again I'd be highly surprised if the actual "Skylon" design gets built as it has some issues that need more work, but the work REL has already done address some general known issues relating to hypersonic, high altitude, and trans-orbital flight, just not to the level that Skylon would be considered an "actual" design in it's present form.

More in the next post because addressing the assumptions in the rest is going to be a bit long... And "I" said that so you've been warned :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: e of pi on 08/11/2016 05:32 PM
Exactly. What makes SABRE unique is the air breathing phase. Once you are above the atmosphere (or cease collecting O2), then it is no different than a normal rocket engine. And that is where staging - if one wanted to do it - would make sense.
There's also the thing that makes Skylon's airframe unique: astoundingly low dry mass. To use the D1 specifications, which I know are no longer the latest but are the most complete I have to hand:

SABRE makes a T/W of about 14, with a thrust of 2000 kN. That's a dry mass of about 14,500 kg per engine. Two is 29 metric tons.
Landing gear is about 2-7% of the GTOW, typically in the 4% ballpark. On the low side, that's 6,500 kg, but on the high side as much as 22,700 kg. A reasonable guess might be 12,000 metric tons.
Thus, the mass of the remainder of the airframe--engines and tanks--is the 53 metric ton total structure minus these. That's about 12 metric tons using the 4% GLOW landing gear assumption.

That'd make Skylon--including its wings, engine nacelles, and cargo bay all wrapped up in an orbital-capable TPS--about as mass efficient as the Space Shuttle SLWT. To be fair, the SLWT isn't common bulkhead and was designed to deal with the TAOS Shuttle, so it has an intertank and heavy thrust beam. OTOH, Skylon has an equally large (actually larger) cargo bay and a wing spar in about the same spot.

It seems like the real magic of Skylon isn't its engine--it's the structure.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: ChrisWilson68 on 08/11/2016 05:46 PM
It just seem that we armchair engineers who really have no experience on real rockets seem to think we known more about developing rockets and spacecrafts than guys like Alan Bond who have done it for >35 years

No, we think the thousands of engineers who have successfully built and flown all the dozens of multi-stage launch vehicles that have actually flown to space know more than Alan Bond, who hasn't actually designed anything that has successfully flown to space, in spite of trying for > 35 years.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: ChrisWilson68 on 08/11/2016 06:11 PM
Thank God for China, rescuing this thread from whining about SpaceX:

Looks like they're developing their own version of Skylon.

And good for them, as Europe is too timid to fully fund such a huge sum for the full-up space plane and Reaction Engines refuses to come up with a more practical, gradual plan to develop a reusable orbital vehicle.

What's more practical in having three sets of heavy engines instead of one set of engines?

The correct answer to this question is "it depends".

Anyone who thinks the answer is always that one set of engines is better than three is a fool.  It absolutely depends on the details.  In real life there are trade offs.  Having only one set of engines has obvious advantages.  There are other advantages to having multiple sets of dissimilar engines, including the fact that each can be optimized for a different purpose and the costs can be lower by not trying to have one designed do three different things.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Paul451 on 08/11/2016 06:33 PM
Do you have a successful comparison?
So we're clear you DO know who Marquardt was, right?
Bankrupt.
After being quite lucrative over decades and it actually still exists IIRC so my point stands.

The US company that made ramjets went quite spectacularly bankrupt and was sold for about $1m. The unrelated German company that makes electronics still exists and is quite successful.

so my point stands.

I'm pretty sure at this stage neither of us is anywhere near the point. The point has wandered off to get a drink and is now standing by the front door, glaring and tapping its watch.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Paul451 on 08/11/2016 06:44 PM
Perhaps because every time someone suggested an alternative (especially TSTO), they were jumped over by the true-believers who insisted that Skylon was the one-true-design, perfect in every way, and anything else was madness and ignorance.
If you want runway to orbit you need a SABRE cycle. If you do not then whatever it is is not a SABRE cycle. REL are probably the lead developers on those as well with the Scimitar. Call it whatever you want, but it's not a SABRE.

John, Scimitar lacks a rocket component. At what altitude do you believe a TSTO stages at? (I wonder if you aren't instead picturing a carrier aircraft for an air-launch system like Pegasus or Stratolaunch or VG.)

It's just a series of logical questions.  It's a question of what a prospective customer wants and do they understand what they are getting. Saying you want TSTSO and SABRE is simply illogical.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Lars-J on 08/11/2016 08:46 PM
It seems like the real magic of Skylon isn't its engine--it's the structure.

Perhaps, but that is also the part of Skylon that has had the least amount of work, and the most amount of hand-waving. And there is much skepticism about its mass efficiency as well.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 08/11/2016 09:24 PM
It's just a series of logical questions.  It's a question of what a prospective customer wants and do they understand what they are getting. Saying you want TSTSO and SABRE is simply illogical.

Eh, no. Because it could be VERY likely that the prospective customer WANTS a TSTO powered by SABRE because he fully understands what he WANTs to get and those pushing SABRE as usable only on an SSTO airframe are unaware of, or just don't care what the CUSTOMER wants or needs. Saying it's illogical[/] is an attempt to 'intimidate' the argument into arriving at the preferred conclusion rather than actually using, you know, 'logic' and more importantly customer/market inputs which may in fact be the opposite of your own!

(And ya, Paul I've seen this stuff quite often but having been on the SpaceX boards I can say it mostly hasn't been as "jumped-on" as it gets there :) )

JS19 and others are simply making some assumptions that not even REL has made based on some assumptions that REL has made which pertain to operations and economics which themselves are based on some limited modeling for a specific outcome. And outcome which actually hasn't reflected the actual market or business planning needs of known users for several decades. REL knows this as they have been playing with words since the start to cover this point which is one of the reasons people have general doubts about how serious REL is and what, exactly, they are attempting to sell.

Quote
I'm quite sure there is plenty about Skylon that has deliberately been left low resolution so the vehicle consortium can impose their own mark on the design but I also expect it would take a lot of effort to come up with a design that looked radically different that can do the job as well as Skylon is expected to.

Actually it's ALL pretty 'low-resolution' since REL is and continues to be, (and they state this pretty regularly) NOT an airframe designer/maker. Therefor while what REL has done so far can be used as a beginning, anyone who takes on the actual design is going to make significant changes as it progress. Assuming they don't go with a different design all together once ALL the trades are done. It might eventually look somewhat like RELs "Skylon", (I'd think more like the cFASST in that case) but going to an actual flying vehicle will take about as much work with or without the REL work.

Quote
Once you understand the massive CoG and CoL shifts during the M0-M23-M0 flight path and you want an easily controlled vehicle the Skylon configuration is tough to beat.

Eh, again, that's not really accurate as the CoG and CoL shifts are well known and can be effectively countered with a number of configurations. I know you're aware of all the aerospace work on airframe design done over the decades and controllability of the various designs was only an issue with one specific rather recent design concept that started with some fundamental flawed assumptions. (And no we aren't talking NASP as aerodynamically it was fine, the main problems were unrealistic propulsion assumptions and requiring flying inside the atmosphere at Mach-25 in order to 'justify' afore mentioned propulsion system)

Any configuration which places its propulsion system near the CoG/CoL interface tends to negate the severity of the shift during high speed flight in a aerodynamic, lifting trajectory. Most combined cycle propulsion system vehicles are designed in this manner for that reason.

"Skylon's" general design is, (and REL has stated this before) very basic for a number of reasons. They wanted to be conservative, they didn't want to put to much effort into refining an airframe as they are not an airframe company but an engine company and needed an 'airframe' for reference purposes, but most importantly because it IS a reference design rather than the required design for the use of the SABRE engine. Not to put too fine a point on it but the way "Skylon" is designed is so that what "engines" it has in the place it has them does not matter very much to the calculations of the overall flight and trajectory modeling.

"Skylon" is designed the way it is simply to allow REL to ignore most vehicle effects on the engine operation and vice versa to allow a very simple and quick calculation set to be used with minimum changes during design iteration. That in no way means it is in fact the best, or most optimum design and in fact it's obviously not with what we know of high speed design.

I know this was mentioned but can't find it but that's the main reason the engines are on the wingtips because by placing them there you can in fact simply change certain assumptions and values and arrive at nearly the same outcome at the checkpoints along the flight trajectory without having to make significant changes to the overall "design" which has far to many 'down-stream' effects in any other position. "Skylon" is not an optimized design by any means and as e of pi points out the dry mass is optimistic to say the least, especially for a vehicle that is supposed to be able to be rapidly turned and serviced. Significant mass growth from design to operation is a given unless someone is willing to spend a LOT of money on materials and technology and that's not (as we're all well aware) very often conducive to economic construction or operation.

I seem to recall that the "Skylon" design can handle up to 15% lower engine performance and still be able to meet the given design goals. (I'll be corrected if I'm wrong, probably several hundred times I'm sure :) ) I thought I'd mentioned this but if so it probably got lost, but while that's a good margin it's actually not the one that people who actually design vehicles tend to be worried about. (A worry but not THE worry in other words)

http://www.sciencedirect.com/science/article/pii/S0094576509004998

Ballpark inert mass growth during development can be anywhere from 10% (highly unlikely) to 50% (same) but is averages around 20% to 30% which also cuts into your margins. 5% engine short-fall and 25% inert mass growth combined means "Skylon" has no payload, not to orbit anyway and there are standardized formulas for figuring a rough set of growth parameters for a vehicle design. I'm betting REL used them too. It doesn't really matter because aerospace designers and manufacturers use them too, for very preliminary designs and they rarely carry over to the actual vehicle. And the bigger the vehicle the more likely for mass growth is. (Yes in some ways a bigger vehicle can absorb more and it averages out but as always ANY SSTO design is more sensitive to the combined factors. Less than a pure-rocket VTVL SSTO but it is not inconsequential. And yes a two or more stage design is also susceptible to mass growth but it actually starts with higher margins to begin with)

When someone suggests something stupid(like using SABRE on TSTO craft) he reveals his ignorance about Skylon/SABRE.

Really? Considering that to actually PERFORM the comparable mission that REL 'designed' "Skylon" to perform, (matching EELV payload to DESTINATION, not ORBIT) REL uses a second stage that "Skylon" has to recover, (there's an operational glitch there a TSTO doesn't have) and return you really think that? Let me point out that almost ALL the advantages cited for SSTO ignore the obvious fact that simply getting a payload to 'orbit' is in fact not very useful and the proper amount of payload has to be delivered to a usable orbit or its worthless? The main point of SSTO has always been based on the idea that a single-stage would be more economic to operate and in fact the amount of payload delivered, and where it is delivered is secondary. That turns out to be quite opposite of the requirements of the people who would be using them though. SSTO's, or pretty much any LEO orbital deliver systems, require to carry or be paired with on-orbit infrastructure, (usually in the form of some sort of Space-Tug or carried propulsion stage, Skylon's US, Shuttle Centaur, Shuttle Agene and PAM being examples) to meet market/customer requirements while, (obviously) multi-stage vehicles have this capability inherent. This is why straight up comparisons rarely work.

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And John Smith 19 explained well in his post why SABRE on TSTO craft is stupid.

Your premise would seem to be fundamentally flawed. Nothing in JS19's post shows that SABRE is "stupid" to use in a TSTO design he simply STATES that it is by inferring it is ONLY capable of being used in that role with no supporting evidence. (He's also got an issue with inferring that it is the ONLY system capable of doing so which is also unsupported) Nothing inherent in the SABRE prevents its use in a TSTO vehicle and REL has stated that it's not an optimum solution but have never given the impression that it's "stupid" or impossible. The main issue is that there is an assumption that a TSTO would not use the SABER in a similar manner to an SSTO for portions of the flight.

Check me here:
Take off from a runway
Accelerate to @Mach-5 using deep-cooled air breathing rocket power
Switch to straight Hydrolox rocket power and continue accelerating
Continue accelerating to orbital speed
Deploy payload with upper stage
Reentry atmosphere
Land on runway

Compare:
Take off from a runway
Accelerate to @Mach-5 using deep-cooled air breathing rocket power
Switch to straight Hydrolox rocket power and continue accelerating
Deploy upper stage with payload
Upper stage continues to accelerate to orbital speed (Note US can be fully reusable and capable of returning to Earth by itself)
Reentry atmosphere
Land on runway

Which parts can SABRE not do?

Quote
It just seem that we armchair engineers who really have no experience on real rockets seem to think we known more about developing rockets and spacecrafts than guys like Alan Bond who have done it for >35 years and also learned lot from earlier failures, and when our stupid ideas are shot down by other people, we cannot take it well.

Just so you are aware, Alan Bond has NEVER said that using SABRE on a TSTO is "stupid" or can't be done. That would be the "armchair engineers" around here. He said it wasn't the optimum use but not that it wouldn't or couldn't work. Nothing that he's said, written or done indicates that SABRE ONLY works on SSTO vehicles and he's experienced enough to know better than to make such a claim where as some "armchair engineers" obviously don't so quoting his experience and wisdom to support something he himself never said or inferred IS rather 'stupid' don't you think?

Further and probably more importantly Alan Bond (and this is NOT a dig or dissing him) is NOT actually a aerodynamics or spacecraft engineer, he's a mechanical and propulsion engineer. Lets be clear at least. No one at REL is in fact an experienced hypersonic aircraft designer or engineer (and there ARE a lot of those around) and the Skylon is "designed" to fulfill a set of criteria based on certain assumptions using the simplest possible vehicle design and standard DSMC modeling without that experience and expertise. Given the fact that Skylon as designed is only a very low resolution basic vehicle design for calculations of what is possible with the assumed performance of the SABRE engine the work done is sufficient to show that if the all the assumptions hold up the design is probably viable in basic function.

That does not translate to being viable or even desirable until a lot more 'variables' have been defined completely by people who have the applicable skill sets. Before that however the engine has to be proven and actual performance parameter data gathered which is what REL is really all about.

Rejection is a part of being on these forums and trying to interact with professionals and knowledgeable amateurs is part of the fun of being here. The people posting back and forth for the most part have been on here and "won" and "lost" quite often and fully understand that most of what we discuss here won't effect those working on the real projects one bit so I'd say we all assume our "stupid" ideas will be stressed tested on a regular basis. Those that can't handle it well simply don't stay.

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When people propose something smart/reasonable alternative to skylon, like different aerodynamic configuration for SSTO craft using SABRE, they are treated well

Have you actually read and understood what that paper is about? First of all it's essentially attempting to use a greatly simplified aero-heating program in place of the standard, more complex one in regards to a "simple" aerodynamic shape as compared to a more "complex" one. (Bottom line is if you're going for very simple and quick calculations as long as you keep in mind the variables and limitations and there are a lot of them, the new program works to a degree) Secondly note that the configuration changes were to make "concessions to ease manufacturing and structural efficiency" but that it is essentially a re-skinned Skylon with more efficient aerodynamic design.

The paper doesn't show much new as REL was/is well aware that the Skylon is NOT an optimized design but a general one. It has issues which will require someone with more time, money and engineers to address sufficiently. And once having done so the result may (probably in fact) will look very little like the Skylon as currently designed.

Despite the look the cFASST-1 design changes very little of the basic Skylon design and already (this is shown both with the simpler HyFlow and the more complex and encompassing DSMC models) large changes are observed. It is obvious that more fundamental changes using well known high-speed/hypersonic methods will yield equally large changes and efficiencies.

For example:
Note the engines remain in the same place on cFASST. That is NOT because that is the only place that SABRE will work, nor is it because that position is the perfect position for an air breathing engine because it's very much not. Again it's to keep the calculations and formula simple so there is no need to calculate airframe/engine interaction. Experts are well aware that there are large increases in efficiency when engines and airframe are more integrated than when they are not, but the interaction also gets very complex very quickly. This is not in fact a bad thing as the more integrated the engines/airframe the greater efficiency overall both have. (For example both inlet and exhaust design gets simpler and overall propulsion efficiency increases when you can use the airframe as part of the system. It can cost some complexity in airframe thermal management but it can yield double digit efficiency % in overall performance)

None of this precludes the design from being used in a TSTO launch system. The paper notes that "Optimization to include low-speed, low altitude flight will almost inevitably result in a configuration that is at least partially aircraft like and thus a vehicle which geometrically is more complex than space vehicles that have been designed in the past." That's very true but if you follow that logically then the conclusion also follows that something designed to be optimized for one regime will, by it's nature, NOT be optimized for different regimes. So compromises will be required at various points to allow a single airframe to cover all regimes. Whereas two vehicles both optimized for different regimes can, when used in combination be more efficient than a single vehicle.

Staging gets more efficient the higher and faster it's done. A SABRE powered lower stage, air breathing to @Mach-5 before switching to pure rocket can then accelerate outside the effective atmosphere to speeds approaching Mach-10 before releasing a space/very-high hypersonic optimized stage that carries the payload to LEO and beyond. Nothing in the SABRE design prevents this from being possible and it may in fact happen when the actual people who will be building the airframe get done with the trades and design studies.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 08/11/2016 09:34 PM
It seems like the real magic of Skylon isn't its engine--it's the structure.

Perhaps, but that is also the part of Skylon that has had the least amount of work, and the most amount of hand-waving. And there is much skepticism about its mass efficiency as well.

Yes but the POINT here is that it doesn't actually matter because it's not the important bit. That would be SABRE and what seems to confuse people the most. REL is and always has been about SABRE with Skylon there to hang it all together as a concept with some fairly viable numbers to work with, but it has always been SABRE and not Skylon that was the point of the exercise.

If SABRE works as advertised then Skylon is in the ballpark as a viable concept that will require the proper skillset to refine. (Or reject in favor of a more viable design which is always possible as well) But it all boils down to SABRE and Skylon is just a concept to set that into a proper context.

If SABRE test out anywhere near what REL hopes then they won't care if it's hung on a totally different design because they are selling SABREs and that's the end goal they have been working towards.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: ChrisWilson68 on 08/11/2016 09:41 PM
It seems like the real magic of Skylon isn't its engine--it's the structure.

Perhaps, but that is also the part of Skylon that has had the least amount of work, and the most amount of hand-waving. And there is much skepticism about its mass efficiency as well.

Yes but the POINT here is that it doesn't actually matter because it's not the important bit.

It is important, because if the mass fraction of Skylon isn't realistic, Skylon can't reach orbit and is total non-viable.  In that case, SABRE would only have a use in the first stage of a multi-stage vehicle.

Skylon proponents would like everyone to believe that the only thing that was ever in doubt about Skylon was the heat exchanger, and testing that in a room on the ground means there's no more development risk in Skylon, it's just a matter of adding money and it will undoubtedly work as advertised.  Many people don't believe that.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 08/11/2016 11:17 PM
I'll be interested if anything pans out with the RFP for the XS-1...
http://www.space.com/32115-skylon-space-plane-engines-air-force-vehicle.html
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: t43562 on 08/12/2016 05:37 AM

This isn't really news but it's an interesting video about the testing of the ED nozzles:

https://www.youtube.com/watch?v=gMs3G_pFR_k&t=10m15s
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/12/2016 06:31 AM
Quote
Landing gear is about 2-7% of the GTOW, typically in the 4% ballpark. On the low side, that's 6,500 kg, but on the high side as much as 22,700 kg. A reasonable guess might be 12,000 metric tons.
Thus, the mass of the remainder of the airframe--engines and tanks--is the 53 metric ton total structure minus these. That's about 12 metric tons using the 4% GLOW landing gear assumption.
Why are using that figure for brake mass. Where does it come from?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: lkm on 08/12/2016 12:08 PM
Exactly. What makes SABRE unique is the air breathing phase. Once you are above the atmosphere (or cease collecting O2), then it is no different than a normal rocket engine. And that is where staging - if one wanted to do it - would make sense.
There's also the thing that makes Skylon's airframe unique: astoundingly low dry mass. To use the D1 specifications, which I know are no longer the latest but are the most complete I have to hand:

SABRE makes a T/W of about 14, with a thrust of 2000 kN. That's a dry mass of about 14,500 kg per engine. Two is 29 metric tons.
Landing gear is about 2-7% of the GTOW, typically in the 4% ballpark. On the low side, that's 6,500 kg, but on the high side as much as 22,700 kg. A reasonable guess might be 12,000 metric tons.
Thus, the mass of the remainder of the airframe--engines and tanks--is the 53 metric ton total structure minus these. That's about 12 metric tons using the 4% GLOW landing gear assumption.

That'd make Skylon--including its wings, engine nacelles, and cargo bay all wrapped up in an orbital-capable TPS--about as mass efficient as the Space Shuttle SLWT. To be fair, the SLWT isn't common bulkhead and was designed to deal with the TAOS Shuttle, so it has an intertank and heavy thrust beam. OTOH, Skylon has an equally large (actually larger) cargo bay and a wing spar in about the same spot.

It seems like the real magic of Skylon isn't its engine--it's the structure.
I think it needs to be pointed out that your numbers are wildly wrong.
Over the years there have been a large number of published papers detailing Skylon construction so there's no need to guesstimate a whole lot of numbers when you can just read them.
According to documentation the SABRE 3 engines mass 10870 kg for both which at peek can produce a gross thrust of about 4000kN and a net T/W of about 14 (not at the same point in time), and the much discussed innovative undercarriage is 1.5% of GTOW thank to the use of the dumpable water coolant.
A full breakdown of the the Skylon C1 mass budget is available in the documentation  down to a component level in places and  can be reasonably scaled up for the D1.
Skylon C1
Item       Mass (kg)   
         
Main engines 2      10870   
Nacelle, Inlet, Bypass      3922   
Wing      5115   
Fuselage: aeroshell, insulation, structure, payload bay      8130   
Main Tankage, cryogenic insulation      2816   
Undercarriage       4170   
Aerodynamic control, hydraulics      2660   
Auxiliary systems, pressurants, coolants etc      5016   
   Basic Mass      42699
OMS/RCS propellants      2357   
Ascent Fuel      66807   
Ascent Oxidiser      150235   
Propellant margins and residuals      1282   
   Total fluids      220681
         
Mass Margin         0
Payload         11620
   Gross Takeoff mass      275000
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/12/2016 07:59 PM
I'll be interested if anything pans out with the RFP for the XS-1...
http://www.space.com/32115-skylon-space-plane-engines-air-force-vehicle.html
there is no mention of the XS-1 in this article.  There is a claim that SABRE is a LACE, which is disappointing given how long SABRE has been around   :(
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/14/2016 09:07 AM
Here :) Arguing that while it's "non-optimum" it's not only a consideration but, (and I've said this consistently) that the Skylon design itself while it is technically an SSTO vehicle is specifically a TSTD (Two-Stage-To-Destination) design as it's based on the idea of equaling EELV satellite delivery capability. That requires delivery to GTO and Skylon can't do it alone so needs a stage/transfer-vehicle/what-have-you.
True, but GTO is only part of the market and it's very challenging. Using the Skylon Upper Stage splits the design problem into the very tough part (Earth to LEO) and the relatively well understood process of going from LEO to GEO.
Quote
SABRE is an engine designed to accelerate a vehicle from runway to orbit. It is also designed to be testable on the ground. Either it will meet those performance specs or it does not, before you have to install it in a vehicle and fly it.

Either you want an engine that can go from runway to orbit or you do not.

Rather simplistic actually. It keeps being said that if you want an engine for a TSTO you want the Scimitar and not the SABRE because of the mistaken belief that "if you want to go to orbit need SABRE, if you're not going all the way you don't" which is, pardon me BS.
Fair point  :) I was assuming they were drawing the line right on M5 while in the atmosphere. And I know what happens when you assume. If you want to go higher and above then SABRE would be the option. I was also thinking that this is already covered in the DARPA XS-1 programme.  I was also recalling  that REL are aware of the results of the cost modelling in the MUSTARD programme, specifically that if 2 stages are not identical you more than double the budget, because not only do you need their development and engineering budgets, you need one to cover the combined interactions of the stages.

I can see a TSTO architecture where the staging Mach number is gradually raised, lowering the gross weight of the 2nd stage or increasing its payload up to the structural and thermal limits of the 1st stage carrier. But a reusable 2nd stage will still need the full orbital rated TPS anyway while an expendable 2nd stage will never give the cost per flight level of a fully reusable system.
Quote
SABRE isn't a single niche engine no matter what people think though that's what REL WANTS the simple and very obvious truth is it's not that limited of an engine cycle. SABRE is capable of air-breathing up to around Mach-5 pretty easily followed by rocket powered flight, technically up to orbital speed but that should be noted that includes every Mach number short of that speed as well. Note the main difference between SABRE and Scimitar is the latter is designed for extended CRUISE at hypersonic speed while the former is designed as an acceleration engine.
A big difference but I'd say the biggest is that's it's solely an air breather, with no provision to run on LO2.
Quote
"Runway-to-Orbit" is NOT about the engine, as I've often pointed out the SERJ and several other combined cycle engine system are perfectly capable of performing the same mission and have been since the mid-50s.
True. But SABRE's pretty good T/W (for an airbreather) and excellent Isp relax the limits on structural mass quite a lot, and even a TSTO with a rocket only 2nd stage will still be a demanding structure, if only from the heating angle.
Quote
The major problem is they almost all got caught in the two main traps of thinking at the time, (and currently if we are being honest) liquid-air-cycle and SCramjets as "requirements" for operation. "Runway-to-Mach-10-and-500,000ft" would be something that SABRE could and would do as well as orbital flight so trying to say a SABRE is ONLY good for runway-to-orbit and nothing else is simply a bias on the part of the person saying it. :)
That's fair also. It just seems like overkill once you've built a fully orbital engine to not use it as such.Looking deeper into it I just can't see the architecture.

Not going the whole way in a single stage suggests but you are using SABRE suggests you're OK with the engine but don't believe the structure.

The only large reusable high Mach structures I know are the Shuttle, the X37b, X15 and XB70. Except the X37b all have done powered flight inside the atmosphere but only the Shuttle did the whole potential SABRE speed range and only the XB70 could lift its own weight.

 If you're that nervous only a rocket would be acceptably safe for the 2nd stage.

It's this mix of optimism and caution that I'm having trouble with.

So an LH2 powered engine is OK. A truss structure with fibre reinforced glass skin is not OK.
Horizontal separation at high Mach number (that's an assumption but I've hear nothing about a VTO SABRE concept) is OK.
Quote
There's optimum and then there's good-enough either of which SABRE is perfectly capable of handling and still being SABRE.
True. I'd never really thought of Skylon's design being selected because it was easy to anlayse. It seemed to address quite a few problems.  I don't know about "optimum" but I'd certainly say "Good enough" and given the design goals I think it would be difficult to come up with something that looked much different but still gave undisturbed airflow to the engines and a well balanced design.
Quote
That statement actually hurts my brain because it points up a lot of misunderstandings about what REL has done, what they are proposing, and what their goals are. In reverse order; TSTOs have proven advantages over SSTO designs when directly compared and vice-versa so the 'call' to go one way or the other is a business, engineering, and operations decision. Not something you base on optimum use of a specific engine design. RELs "efforts" have amounted to what would be a very preliminary study of a possible airframe that can maybe do "this" with an assumed performance of "this" from the propulsion system.
AFAIK the perceived advantages are an easier design problem as your design is split in two and you can have more structure and a higher payload fraction.

But Skylon was designed to deliver an ELV payload fraction, not the 1% of the Shuttle. For an equal payload I find it very hard to believe a TSTO will be simpler to design, build or test.  I doubt it would be cheaper to operate either.  The big question is the perception of how risky is the Skylon structural design

I know you hate the launch-vehicle-like-an-aircraft analogy but no one has ever built a large 2 stage cargo aircraft, despite the benefits of an enormous 1st stage to get a heavily loaded (and fueled) 2nd stage off the runway and airborne. 
Quote
REL has gone a bit further due to being biased towards an SSTO design but because they are not in fact airframe designers/makers they have missed some obvious areas. Any actual airframe designer/engineer/maker is going to take the "Skylon" design under consideration and then do actual trade studies to define a REAL design capable of doing what the overall business/market/user requires.
I've never doubted that would be the case.
Quote
The REL "Skylon" has a leg up in the preliminaries because of the work REL has done but they didn't do the work to actually DESIGN an airframe, they did the work to define something that by using SABRE engines that meet expectations could do "this" operationally. Someone who's going to make an actual Skylon vehicle will do a lot more detailed and in-depth work which may or may not validate RELs assumptions and combine that with marketing and operational inputs which may not in fact recommend an SSTO design at this time or a different airframe configuration.
If the design assumptions on Skylon are as conservative as you think that seems unlikely barring (again) the perception that HTOL SSTO  is risky and would essentially put the airframer at square 1 in design.
Quote
Again I'd be highly surprised if the actual "Skylon" design gets built as it has some issues that need more work, but the work REL has already done address some general known issues relating to hypersonic, high altitude, and trans-orbital flight, just not to the level that Skylon would be considered an "actual" design in it's present form.
An interesting point. NASA pointed out that SABRE plume heating of the rear fuselage might be an issue, but did you have any others in mind?
Quote
More in the next post because addressing the assumptions in the rest is going to be a bit long... And "I" said that so you've been warned :)
Noted.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/14/2016 09:26 AM
Skylon proponents would like everyone to believe that the only thing that was ever in doubt about Skylon was the heat exchanger, and testing that in a room on the ground means there's no more development risk in Skylon, it's just a matter of adding money and it will undoubtedly work as advertised.  Many people don't believe that.
"Proponents" know the difference between the Skylon vehicle and the SABRE engine.

However someone floating a strawman argument would not care. 

Please stop with the strawman arguments.

Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: ChrisWilson68 on 08/14/2016 06:00 PM
Skylon proponents would like everyone to believe that the only thing that was ever in doubt about Skylon was the heat exchanger, and testing that in a room on the ground means there's no more development risk in Skylon, it's just a matter of adding money and it will undoubtedly work as advertised.  Many people don't believe that.
"Proponents" know the difference between the Skylon vehicle and the SABRE engine.

However someone floating a strawman argument would not care. 

Please stop with the strawman arguments.

REL identified designing and making the pre-cooler as the unknown element in the SABRE design so that's what they went for.

liked by john smith 19:

And for Skylon, they have built the preocooler which is the most important part of the craft.

Quote from: Citizen Wolf link=topic=36826.msg1411621#msg1411621
the SABRE engine is a dual air-breathing AND rocket engine. The air-breathing cycle has a rather nifty and advanced heat-exchanger to stop things melting. If it performs to expectations, SABRE should do SSTO.

Quote from: john smith 19 link=topic=36826.msg1382478#msg1382478
I don't think REL have every really doubted their ability to build SABRE provided a)The pre cooler worked as expected and b) The could get the funding.

The pre cooler has now been extensively tested and worked as expected. Progress milestones then depend on their getting the necessary funding when it's needed.

Quote from: john smith 19 link=topic=24621.msg968948#msg968948
The *real* unknown (and highly worrying) item would be the pre-cooler and it's frost control system.

Which might explain why they went to tackle it first.
I'd suggest a lot about Skylon is beyond the current state of *practice* in *LV* design. A lot of it is well *inside* the state of the art in other areas *if* you broaden your viewpoint and realisze that LV design is *very* conservative.

Quote from: john smith 19 link=topic=24621.msg968948#msg968948
Methods exist in the *aircraft* industry to manage risk in development and schedule. Will they (if *fully* funded) deliver a Skylon to the  *day* set in their schedule? I'd suggest they have as good a chance of doing that as Spacex did when they started.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 08/14/2016 07:22 PM
I don't get the post above?? ???
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: ChrisWilson68 on 08/14/2016 07:28 PM
I don't get the post above?? ???

John Smith 19 accused me of making a strawman argument.  In response, I listed several posts where he and others made the argument I was disputing, showing my argument wasn't a strawman argument.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 08/14/2016 07:41 PM
I don't get the post above?? ???

John Smith 19 accused me of making a strawman argument.  In response, I listed several posts where he and others made the argument I was disputing, showing my argument wasn't a strawman argument.
Oh, ok Chris, thanks... You guys carry on!
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: ChrisWilson68 on 08/14/2016 09:04 PM
John Smith 19 accused me of making a strawman argument.  In response, I listed several posts where he and others made the argument I was disputing, showing my argument wasn't a strawman argument.
Except the quotes you gave didn't make the argument you claimed they were making. I believe he strawman argument it was claimed you were making was not the pre-cooler is a critical component of SABRE, and SABRE is a critical component of Skylon, but that once the pre-cooler was 'solved' everything else would succeeded if given the specified money. I recognise that it wasn't explicitly stated to be the case, but you'd have to be trolling to insist it was about the pre-cooler.

So the first two quotes are about the pre-cooler being important to Skylon, which it is (or at least all versions of the engine so far. Frost control, it seems, was only important to the first three).

The first quote says the pre-cooler is "the unknown element" in SABRE.  The word "the" is even italicized.  The only reason to do that is to say it is the only unknown element.  That implies that everything else in SABRE is known, so given time and money, there isn't anything that would stop it from being built and work as expected.  Isn't that the point of making the distinction between "known" and "unknown" elements?

The second quote was in the context of whether REL has flown anything.  As a reply to the issue of whether they've flown something, it's clear the implication is that they've done the hard part and what's left isn't hard.  And that's for Skylon, not just SABRE.  Otherwise, it doesn't make any sense as a counter to the argument that REL haven't flown anything.

The third quote is slightly ambiguous - from context I'd say it was SABRE that "it" referred to - but even if "it" was Skylon the "if it performs as expected" as a qualifier to me quite clearly means it isn't taken for granted it would succeed give the required money.

It seems pretty clear "it" in the third quote refers to the pre-cooler.  So it's a claim that if the pre-cooler works to expectations, SSO will work.  SSO is a statement about the whole Skylon system, not just SABRE.

Even if "it" was actually supposed to mean SABRE, there's no escaping the conclusion that this quote is claiming nothing in Skylon outside SABRE could possibly be a showstopper.

The fourth quote is an opinion about REL's appraisal of their capability to build the engine, not Skylon. Even if it were about Skylon, it makes no claim as to REL's actual ability, only their assessment.

I claimed proponents of Skylon make this argument.  Here we have a claim that REL itself is making this argument.  Don't you think REL would count as proponents of Skylon?

The fifth quote, I think, is the closest to your characterisation, but the first half is again about pre-coolers and the second part says a lot of Sklyon isn't new - not that none of it is new.

The sixth quote would only back up your characterisation of the argument if you think John Smith 19 believes SpaceX were guaranteed to succeed, or than managing risk means eliminating it.

The fifth and sixth quotes were from the same post.  I tried to cut it down to representative pieces since it was so long.

John here claims that the pre-cooler is the only risky new technology in Skylon.  He lists a bunch of other elements of Skylon and for each claims it has already been done in some other vehicle.  Then he claims that given the funding, REL's chances of success are comparable to those of SpaceX when they started.

But SpaceX really wasn't doing anything new.  It was very clear when they started that there would be no technological showstoppers.  Given enough time and money, Falcon 1 would eventually fly to orbit -- nobody really doubted that.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: ChrisWilson68 on 08/14/2016 09:10 PM
Perhaps we could bypass all this discussion of what people meant in past posts by just asking this question: Do you now agree with this statement: "The pre-cooler was the only significant risk of a technological showstopper for Skylon.  I consider the pre-cooler to have been proven and therefor there is not a substantial risk of a showstopper being found that makes Skylon impossible.  Given enough time and money, Skylon is highly likely to succeed."

If there aren't any people who agree with that statement, we can avoid a whole lot of arguing by agreeing that there are still significant technological unknowns for Skylon that could cause it to be infeasible.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Paul451 on 08/14/2016 09:32 PM
I was assuming they were drawing the line right on M5 while in the atmosphere.

So you made an assumption that made the idea as unrealistic as possible. You actually do that a lot when contrasting Skylon with any alternative, you seem to always pick the worst interpretation of any alternative. (Its actually really common in aerospace, not just amongst us space-nerds. Too many programs were destroyed because someone senior locked into a bad design early by false-comparing to any potential alternative, dooming the program. For example...)

[Re: MUSTARD] if 2 stages are not identical you more than double the budget

{sigh} No, you don't. Engineering never works that way.

That reasoning could only work if the biamese-stages are each of no greater complexity/cost than the non-biamese stages you are comparing to. And that assumption is always wrong.

Biamese/triamese designs never work as claimed. Identical designs for lower and upper stages never saves money compared to separate designs. The differences between the needs of the two flight-regimes always makes developing a single design that can perform both roles, more expensive than allowing the two stages to each follow their own logic. You can make some savings by sharing things like tank-section tooling, engine cores (for rockets, never for air-launched), transport, etc, but for a MUSTARD-style triamese the added complexity of the near-identical designs more than outweighs any savings in shared manufacturing.¹

Just as Skylon will be more expensive to design and develop than a conventional rocket stage - a SABRE-wielding first-stage will carry the overwhelming bulk of the development cost of a TSTO-system. Whereas the development cost of an expendable upper-stage will be on the same order of magnitude as the GTO stage that REL wants - ie, virtually nothing compared to Skylon-proper, and a small proportion of the development cost of a TSTO-Skylon.

Similarly the development cost of a recoverable/reusable upper-stage is primarily the re-entry system, which can be developed incrementally at fairly low cost once you have an commercially operational reusable first-stage.²

¹ The closest we've gotten is that the inefficiencies inherent in triple-coring the first-stage may not always outweigh the savings from common manufacturing, compared to just building unique side-boosters in their own factory. And likewise that the cost benefits of TSTO generally outweighs the theoretical efficiency of 3STO.

² The whole idea of expanding the payload market via a low-cost launcher is predicated on the idea that low cost launches also lower the development costs of novel in-space concepts, therefore increase the number of such projects. The same reasoning applies to the development of a reusable upper-stage once a reusable first-stage exists.

I can see a TSTO architecture where the staging Mach number is gradually raised, lowering the gross weight of the 2nd stage or increasing its payload up to the structural and thermal limits of the 1st stage carrier. [...]

While this is pedantically true, it's clear that when you're talking about staging at certain Mach numbers, you're still talking about in-atmosphere staging. What you wrote here is only true if staging is above the atmosphere, regardless of the staging velocity. Having variable super- and hypersonic staging is a terrible assumption.

It just seems like overkill once you've built a fully orbital engine to not use it as such.Looking deeper into it I just can't see the architecture.

Because you always assume that the first stage of a TSTO will always cost a similar amount to develop as Skylon. Therefore, to you it makes no sense to not develop straight to Skylon. And if your assumption was correct, that would be logical. But that assumption will always be wrong.

Forget whatever weird design you are obviously picturing for a TSTO. Just look at Skylon.

Can you understand that it is going to be structurally easier on the airframe, and structurally and thermally easier on the TPS, if Skylon was re-entering the atmosphere on a sub-orbital ballistic trajectory at Mach 6 or even Mach 10, compared to coming in at Mach 20+ orbital velocity? Can you understand that "easier on..." also means "easier to design"? And that "easier to design" means "cheaper to design"? And that "cheaper" means both sooner and vaster more likely to be funded.

At Mach 6, you are dealing with just 25% of the kinetic energy of Mach 20. At Mach 4, just 10%.

The only way for SSTO-Skylon to be cheaper to design and develop than Skylon-as-a-first-stage is if they've zeroed that difference. Not "reduced by", not "optimised for", but zeroed.

I know you hate the launch-vehicle-like-an-aircraft analogy but no one has ever built a large 2 stage cargo aircraft, despite the benefits of an enormous 1st stage to get a heavily loaded (and fueled) 2nd stage off the runway and airborne.

Actually it's quite routine.

Not only have a large number of experimental aircraft (Wright-flyer, first jets, many X-planes) launched via a separate system (catapult, sled, or jettisonable undercarriage, or launched off-the-back/under-the-wing of an existing aircraft), you also have expendable JATO units and drop-tanks used routinely by the military to boost take-off speed and range, respectively. And of course aerial refuelling is a standard for any mission where the requirements exceed the aircraft. Even when the aircraft is theoretically capable of the distance, the military still uses aerial refuelling or expendable drop tanks (or both!) to extend the performance (increased load-outs, increased loiter or combat time, higher speed for a given range, etc.)

Even with civilian operators, if the aircraft isn't capable of the range, they'll divide the route into stages and have refuelling at each stage. You don't think of that as a "multi-stage" aircraft because the same aircraft lands at each airport alone the route, but if airports along the route were impossible, if refuelling at those points was impossible, then obviously the industry would have had to copy the military model. Things like drop-tanks and aerial refuelling.

Same with multi-modal cargo. If you couldn't use locally operated trucks at shipping ports, the shipping industry would have had to ship its own trucks with every cargo. That drastically lowers your available cargo-mass per ship, which is why we don't do that, but if it was the only game in town, it's what we would do.

And flip side, if it was physically possible to build a spaceport at 50-100km, and ship fuel to that spaceport by less expensive means, it's obvious that we would never use multi-stage launchers, except for extremely unusual bespoke missions (as the military is to general aviation). [We might still have specialised vehicles for each stage - ground-to-magic-spaceport, magic-spaceport-to-orbit - because of the technological demands of each leg. Just as we use different vehicles for multi-modal transport - ships, trains, trucks, vans. But we'd never attach them to each other. If you suggested it, people would just look at you funny.]

The aircraft analogy only fails because people always use it wrong; just as you did.

[edit: minor]
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Paul451 on 08/14/2016 09:40 PM
Perhaps we could bypass all this discussion of what people meant in past posts by just asking this question: Do you now agree with this statement: "The pre-cooler was the only significant risk of a technological showstopper for Skylon.  I consider the pre-cooler to have been proven and therefor there is not a substantial risk of a showstopper being found that makes Skylon impossible.  Given enough time and money, Skylon is highly likely to succeed."
If there aren't any people who agree with that statement, we can avoid a whole lot of arguing by agreeing that there are still significant technological unknowns for Skylon that could cause it to be infeasible.

I think there's another point that needs to made clearer to avoid some of the wasteful back-and-forth:

Do you agree that the Skylon airframe (ie, vehicle sans engine) represents the major cost of developing Skylon as a launcher?

Or instead do you believe that SABRE (or its successors) represents the main cost (or that the two, engine & airframe, are roughly equal)?

agreeing that there are still significant technological unknowns for Skylon that could cause it to be infeasible.

I think that people could agree with your statement, as written, even if they believe that Skylon is 90% engine development, 10% vehicle development.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: lkm on 08/15/2016 09:49 AM


Can you understand that it is going to be structurally easier on the airframe, and structurally and thermally easier on the TPS, if Skylon was re-entering the atmosphere on a sub-orbital ballistic trajectory at Mach 6 or even Mach 10, compared to coming in at Mach 20+ orbital velocity? Can you understand that "easier on..." also means "easier to design"? And that "easier to design" means "cheaper to design"? And that "cheaper" means both sooner and vaster more likely to be funded.

At Mach 6, you are dealing with just 25% of the kinetic energy of Mach 20. At Mach 4, just 10%.

The only way for SSTO-Skylon to be cheaper to design and develop than Skylon-as-a-first-stage is if they've zeroed that difference. Not "reduced by", not "optimised for", but zeroed.



This might be the source of much confusion. According to REL ( I believe Hempsell told us this on a previous thread) it's not actually clear that reentry is thermally worse on Skylon than Mach 5 air breathing as thanks to it's very low ballistic coefficient Skylon has a very benign reentry, at least according to DLR cfd modelling. One has slightly higher peak temperatures and the other longer heat sink, I forget which.
So at first pass any SABRE based TSTO flying the same sort of air breathing trajectory has to be equipped with the same level of TPS, at least until you have some modelling that says it doesn't need it. Also a TSTO is going to have a higher ballistic coefficient and be reentering lower so until you actually have some data I don't think you can actually confidently say that the reentry is going to be more benign that Skylon.

In short hypersonic air breathing is really hard on an aircraft, there's a reason REL believe Skyon is an easier build than A2, and whether you're going to orbit or not thermally and structurally it's likely  to be largely driven by that.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: t43562 on 08/15/2016 02:50 PM
I note that this vacancy has been on offer since the end, I think, of July:

http://www.reactionengines.co.uk/careers_035markcommsmanager.html

I'm sure we're all looking forward to seeing it filled :-)
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Star One on 08/15/2016 03:11 PM
I note that this vacancy has been on offer since the end, I think, of July:

http://www.reactionengines.co.uk/careers_035markcommsmanager.html

I'm sure we're all looking forward to seeing it filled :-)

It closed yesterday surprised it's not been removed from the site.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: high road on 08/15/2016 08:40 PM
Considering this subject has been debated for five endless threads, might it not be time to give it a dedicated update thread, and (/or if it already exists) link to it in the first post of these semantics discussion threads?

Updates don't need to be major news, any news from a reliable source would be interesting.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/15/2016 10:56 PM

This isn't really news but it's an interesting video about the testing of the ED nozzles:
Most interesting

The use of STOIC to investigate the air breathing to rocket transition is quite interesting since this was one of the other risk areas for SABRE. The fast acting flow valves that AE have developed are also quite intriguing. I wonder if they are a big enough improvement on COTS hardware AE might consider starting to sell them as a product?

I think the indication that the REL E/D nozzle design will be different and have lower cooling requirements is news, but it may have turned up before and I may simply have not have been following things closely enough to pick it up before.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/16/2016 12:58 PM
Eh, no. Because it could be VERY likely that the prospective customer WANTS a TSTO powered by SABRE because he fully understands what he WANTs to get and those pushing SABRE as usable only on an SSTO airframe are unaware of, or just don't care what the CUSTOMER wants or needs. Saying it's illogical[/] is an attempt to 'intimidate' the argument into arriving at the preferred conclusion rather than actually using, you know, 'logic' and more importantly customer/market inputs which may in fact be the opposite of your own!
TBH I sincerely hope so.  :). I just can't figure out where they want to draw the line that gives you a much better system.  The known  SoA for powered flight is the X15 but that was designed to operate long enough to soak the whole airframe.  I think you could use the same materials (since materials and structure would seem to be the the concern here) to build a SABRE powered 1st stage to go to the X15's top speed.  This would have major implications for the size and payload of any 2nd stage.
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JS19 and others are simply making some assumptions that not even REL has made based on some assumptions that REL has made which pertain to operations and economics which themselves are based on some limited modeling for a specific outcome. And outcome which actually hasn't reflected the actual market or business planning needs of known users for several decades. REL knows this as they have been playing with words since the start to cover this point which is one of the reasons people have general doubts about how serious REL is and what, exactly, they are attempting to sell.
Care to expand on that? IMHO the economic model is every bit as important as the thermal cycle model.
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Eh, again, that's not really accurate as the CoG and CoL shifts are well known and can be effectively countered with a number of configurations. I know you're aware of all the aerospace work on airframe design done over the decades and controllability of the various designs was only an issue with one specific rather recent design concept that started with some fundamental flawed assumptions. (And no we aren't talking NASP as aerodynamically it was fine, the main problems were unrealistic propulsion assumptions and requiring flying inside the atmosphere at Mach-25 in order to 'justify' afore mentioned propulsion system)
That's my point. People know this is an issue yet insist on designing vehicles that will have problems and then complain they can't get the design to work.
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Any configuration which places its propulsion system near the CoG/CoL interface tends to negate the severity of the shift during high speed flight in a aerodynamic, lifting trajectory. Most combined cycle propulsion system vehicles are designed in this manner for that reason.
I think NASA was going to do one of these with the engines half way up the body.  Given that they've flagged plume impingement as a potential issue on Skylon I could not see how they'd avoid the rear fuselage getting quite "toasty."
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I know this was mentioned but can't find it but that's the main reason the engines are on the wingtips because by placing them there you can in fact simply change certain assumptions and values and arrive at nearly the same outcome at the checkpoints along the flight trajectory without having to make significant changes to the overall "design" which has far to many 'down-stream' effects in any other position. "Skylon" is not an optimized design by any means and as e of pi points out the dry mass is optimistic to say the least, especially for a vehicle that is supposed to be able to be rapidly turned and serviced. Significant mass growth from design to operation is a given unless someone is willing to spend a LOT of money on materials and technology and that's not (as we're all well aware) very often conducive to economic construction or operation.
That's certainly been historically true. Manual tracking of part masses meant recalculating a new empty mass would be a major exercise.  But with BoM properties in a database (or at this level of fidelity a set of spreadsheets) propagating a part mass change through the design (although not the change on the mass of associated parts) should take seconds, giving an early warning that other part will need to be re-designed or re weighted. 
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I seem to recall that the "Skylon" design can handle up to 15% lower engine performance and still be able to meet the given design goals. (I'll be corrected if I'm wrong, probably several hundred times I'm sure :) ) I thought I'd mentioned this but if so it probably got lost, but while that's a good margin it's actually not the one that people who actually design vehicles tend to be worried about. (A worry but not THE worry in other words)
REL treated Skylon  as aircraft, so they applied aircraft margins.
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http://www.sciencedirect.com/science/article/pii/S0094576509004998
Interesting abstract.  The "exchange rate" of 1 Kg on the Apollo Ascent Stage --> 800Kg on the Saturn V demonstrates why Logsdon's and Africano's paper is well worth reading.
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Ballpark inert mass growth during development can be anywhere from 10% (highly unlikely) to 50% (same) but is averages around 20% to 30% which also cuts into your margins.
With the proviso we're talking VTO TSTO rockets.
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5% engine short-fall and 25% inert mass growth combined means "Skylon" has no payload, not to orbit anyway and there are standardized formulas for figuring a rough set of growth parameters for a vehicle design. I'm betting REL used them too. It doesn't really matter because aerospace designers and manufacturers use them too, for very preliminary designs and they rarely carry over to the actual vehicle.
REL have been very careful to work with industry standard methods so that anyone looking over their work (like potential investors) can follow the trail from objectives back to how they are going to be carried out. Sadly these include the cost models that predicted SX would have to have spent about $2Bn up to the first F9 flight, but they are the industry standard.  :(
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And the bigger the vehicle the more likely for mass growth is. (Yes in some ways a bigger vehicle can absorb more and it averages out but as always ANY SSTO design is more sensitive to the combined factors. Less than a pure-rocket VTVL SSTO but it is not inconsequential. And yes a two or more stage design is also susceptible to mass growth but it actually starts with higher margins to begin with)
That ability to absorb mass growth would seem to be the virtue of those giant Philip Bono 1960's designs, although drag is a problem if you're going with the idea of a "micro launcher." so somewhere in between seems to be minimum trouble.
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The main point of SSTO has always been based on the idea that a single-stage would be more economic to operate and in fact the amount of payload delivered, and where it is delivered is secondary. That turns out to be quite opposite of the requirements of the people who would be using them though. SSTO's, or pretty much any LEO orbital deliver systems, require to carry or be paired with on-orbit infrastructure, (usually in the form of some sort of Space-Tug or carried propulsion stage, Skylon's US, Shuttle Centaur, Shuttle Agene and PAM being examples) to meet market/customer requirements while, (obviously) multi-stage vehicles have this capability inherent. This is why straight up comparisons rarely work.
I'd point out that REL (as Hempsell said) sized Skylon to do a comm sat mission to orbit. Historically they assumed that the payload would carry it's own engine to handle GTO. Other payloads to LEO would then be free to use the payload for that stage for their own uses. Note it's the end users issue to get such a stage.  ESA advised them offering an upper stage would make the system more flexible, and now it's in the development plan.

Looking back it's a question of where you draw line on the stages maximum trajectory. Skylon's "first" stage gets you to orbit (which can be up to 600Km) , which for a lot of Earth Observation payloads would be enough. All other LV get you to maybe M10, but typically their 2nd stage can get you to GTO or even escape. A fairer comparison would be a TSTO just to LEO, then a third stage for anything about that.

A Skylon "first stage" is useful on its own. No other first stage is, unless people were prepared to do significant redesign and take a major cut in payload.
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Your premise would seem to be fundamentally flawed. Nothing in JS19's post shows that SABRE is "stupid" to use in a TSTO design he simply STATES that it is by inferring it is ONLY capable of being used in that role with no supporting evidence.
Actually I checked my posts and have not called it stupid. I just could not see why you would. It seemed a "sub optimal"  to me. I can now see that an argument can be made but I've also recalled this came up with the question of how much a Skylon could carry sub orbitally. REL reckoned it was 2x their payload to orbit but the separation was quite risky and the payload would need something like 100-1500m/s (IIRC). Hempsell said they discontinued modelling on it as no one seemed that interested and you'd still need to build a Skylon to do it.
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(He's also got an issue with inferring that it is the ONLY system capable of doing so which is also unsupported)
That's not quite correct. Pure rocket could do it if you can get the structural mass down, and that seems very tough. Anything needing deep pre cooling prior to REL's work I'm very doubtful about due to frost control and anything air breathing will need to have good air breathing Isp to swallow the loss in T/W. Anything that air breathing and  VTO means very low structural weight x (relatively) low T/W --> unlikely despite high AB Isp.
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Nothing inherent in the SABRE prevents its use in a TSTO vehicle and REL has stated that it's not an optimum solution but have never given the impression that it's "stupid" or impossible. The main issue is that there is an assumption that a TSTO would not use the SABER in a similar manner to an SSTO for portions of the flight.

Which parts can SABRE not do?
Not stupid, just seemed an odd idea.
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Further and probably more importantly Alan Bond (and this is NOT a dig or dissing him) is NOT actually a aerodynamics or spacecraft engineer, he's a mechanical and propulsion engineer. Lets be clear at least. No one at REL is in fact an experienced hypersonic aircraft designer or engineer (and there ARE a lot of those around) and the Skylon is "designed" to fulfill a set of criteria based on certain assumptions using the simplest possible vehicle design and standard DSMC modeling without that experience and expertise.
I'd be wary of that. Their work on E/D nozzle design (and improvement) and work on the inlets suggests they either have hypersonic experience on staff or access through partner companies.
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Given the fact that Skylon as designed is only a very low resolution basic vehicle design for calculations of what is possible with the assumed performance of the SABRE engine the work done is sufficient to show that if the all the assumptions hold up the design is probably viable in basic function.
Which is pretty much SOP for all engineering projects, establishing that a design is possible if "Component X" can deliver these specs.
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That does not translate to being viable or even desirable until a lot more 'variables' have been defined completely by people who have the applicable skill sets.
True, and a bit of a chicken and egg situation. Hopefully BAE will be able to provide some "sanity checking,"  although I would have expected the ESTECH  to identify any issues like this already.
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When people propose something smart/reasonable alternative to skylon, like different aerodynamic configuration for SSTO craft using SABRE, they are treated well

Have you actually read and understood what that paper is about? First of all it's essentially attempting to use a greatly simplified aero-heating program in place of the standard, more complex one in regards to a "simple" aerodynamic shape as compared to a more "complex" one. (Bottom line is if you're going for very simple and quick calculations as long as you keep in mind the variables and limitations and there are a lot of them, the new program works to a degree) Secondly note that the configuration changes were to make "concessions to ease manufacturing and structural efficiency" but that it is essentially a re-skinned Skylon with more efficient aerodynamic design.

The paper doesn't show much new as REL was/is well aware that the Skylon is NOT an optimized design but a general one. It has issues which will require someone with more time, money and engineers to address sufficiently. And once having done so the result may (probably in fact) will look very little like the Skylon as currently designed.

Despite the look the cFASST-1 design changes very little of the basic Skylon design and already (this is shown both with the simpler HyFlow and the more complex and encompassing DSMC models) large changes are observed. It is obvious that more fundamental changes using well known high-speed/hypersonic methods will yield equally large changes and efficiencies.

For example:
Note the engines remain in the same place on cFASST. That is NOT because that is the only place that SABRE will work, nor is it because that position is the perfect position for an air breathing engine because it's very much not. Again it's to keep the calculations and formula simple so there is no need to calculate airframe/engine interaction. Experts are well aware that there are large increases in efficiency when engines and airframe are more integrated than when they are not, but the interaction also gets very complex very quickly. This is not in fact a bad thing as the more integrated the engines/airframe the greater efficiency overall both have. (For example both inlet and exhaust design gets simpler and overall propulsion efficiency increases when you can use the airframe as part of the system. It can cost some complexity in airframe thermal management but it can yield double digit efficiency % in overall performance)
I did not know it was that high.  But remember the old rule of software development
"Optimization is the root of most evil."

IIRC In the X30 programme "complexity in airframe thermal management" meant a)Building large chunks of design in RCC or b) going with active cooling.  AFAIK Skylon aims to make very limited use of either.

Everything has a price. Is that increased efficiency a) Affordable b) Needed ? NASP needed it with an engine  T/W ratio of 2:1 but does SABRE?
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None of this precludes the design from being used in a TSTO launch system. The paper notes that "Optimization to include low-speed, low altitude flight will almost inevitably result in a configuration that is at least partially aircraft like and thus a vehicle which geometrically is more complex than space vehicles that have been designed in the past." That's very true but if you follow that logically then the conclusion also follows that something designed to be optimized for one regime will, by it's nature, NOT be optimized for different regimes. So compromises will be required at various points to allow a single airframe to cover all regimes.
The inverse problem is IMHO trickier. Ensuring any improvement in a subset of the flight envelope does not make other parts of the envelope worse to the point the design won't work. A TSTO would open up options at the cost of designing 2 vehicles to do so.
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Whereas two vehicles both optimized for different regimes can, when used in combination be more efficient than a single vehicle.

Staging gets more efficient the higher and faster it's done. A SABRE powered lower stage, air breathing to @Mach-5 before switching to pure rocket can then accelerate outside the effective atmosphere to speeds approaching Mach-10 before releasing a space/very-high hypersonic optimized stage that carries the payload to LEO and beyond. Nothing in the SABRE design prevents this from being possible and it may in fact happen when the actual people who will be building the airframe get done with the trades and design studies.
With that staging velocity you could consider a very conventional expendable liquid upper stage. One notion I've wondered about would be wrapping 2 half circular wings rounds such a stage on pivoting on a structure like a piano hinge with some kind of "aerospike" or "aerodisk" to improve the aerodynamics of the flat front end. Such an empty stage should begin  entry at a very high altitude, but again has all the issues of being back end heavy of the shuttle without it's control surfaces.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 08/16/2016 01:14 PM
To jog your memory John, the X-15A2 needed repairs after the flight. The ablative TPS would need to be upgraded for a prolonged hypersonic flight regime...

https://www.youtube.com/watch?v=wQGnwXRFum8
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 08/16/2016 05:26 PM
True, but GTO is only part of the market and it's very challenging. Using the Skylon Upper Stage splits the design problem into the very tough part (Earth to LEO) and the relatively well understood process of going from LEO to GEO.

True, period actually :) While the following argument is technically true the main point being addressed is that by comparing and designing to the same abilities, (which is supposed to have been done with Skylon) as the EELVs the comparisons fully FAIL if they are only applicable to a part of the EELV mission profile and ability. GTO was in fact the MAIN mission of the EELV not delivery to LEO which arguably is the main mission of the Skylon design as that's what it's designed to do. GTO may be only "part" of the market but it's been the biggest segment monetarily and remains so and while the "tough" part may be surface to the point where the second stage is released to continue to GTO neither SSTO in general of Skylon in particular makes much difference. It's still "tough" and somewhere in there the second half of the journey has to be addressed and designed for and just because it's a relatively understood process doesn't make it simple or cheap.

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Fair point  :) I was assuming they were drawing the line right on M5 while in the atmosphere. And I know what happens when you assume. If you want to go higher and above then SABRE would be the option. I was also thinking that this is already covered in the DARPA XS-1 programme.  I was also recalling  that REL are aware of the results of the cost modelling in the MUSTARD programme, specifically that if 2 stages are not identical you more than double the budget, because not only do you need their development and engineering budgets, you need one to cover the combined interactions of the stages.

The "line" of Mach-5 was given for the last Skylon trajectory I recall but somewhere between there and Mach-6/7 things begin to get 'difficult' if you want to continue air-breathing without significant design work and integration of vehicle/engines which REL appears to want to avoid. Somebody planning on doing it regularly, and economically will probably find the work more worthwhile since they are in fact doing a more in-depth and fuller analysis. The XS-1 program appears to be specifically avoiding any possible air breathing designs so is probably not a valid comparison. (It is also specifically aimed at vertical take off modes it seems) In general though air-breathing to Mach-5 (rarely up to Mach-8 without using a SCramjet) has been a general design cut off in concepts wanting to avoid excessive aero-heating issues no matter the engine placement or construction details.

It should be recalled that specifically the MUSTARD program was an attempt to significantly find methods of reducing the cost of a multi-stage launch vehicle WITH many assumptions loaded up-front that later turned out to be not as true as they were presented. The cost per stage modeling was one of those assumptions that proved less than accurate specifically as noted in one of the follow up posts. As to the interaction between stages, using MUSTARD for anything, specifically for something that's NOT a vertical take-off, pure rocket design, is highly misleading both in scope and results. Especially when you are required to use multiple vehicles of a non-optimized design as a basis.

The similar US IIRLV study, with initially similar assumptions but not tied to any single required design, noted that while identical stages would be optimum actually doing so would require much more expensive and complex vehicles and so recommended two different designs between the booster and orbiter for that very reason. The cost modeling showed that using two separate designs rather than a single non-optimum design was more cost effective overall. Hence the conclusions MUSTARD reached were in question already.

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I can see a TSTO architecture where the staging Mach number is gradually raised, lowering the gross weight of the 2nd stage or increasing its payload up to the structural and thermal limits of the 1st stage carrier. But a reusable 2nd stage will still need the full orbital rated TPS anyway while an expendable 2nd stage will never give the cost per flight level of a fully reusable system.

The difference at the most basic level is that a designed from the start recoverable second stage can have optimized and cost effective TPS and structure which is now not required on the first stage. And is doing so can have more capability built in than an optimized SSTO design because of those capabilities. And careful with that second part as we already know "flight level" is a tricky measurement and expendables can in fact be cost effective under the right conditions :)

Lastly an optimized upper-stage can in fact have a much BETTER TPS than just "orbital" and can be optimized for much greater efficiency in that role which while it might be more expensive to design and develop will cost far less than something like the SUS or space tug in long term operational use.
 
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That's fair also. It just seems like overkill once you've built a fully orbital engine to not use it as such. Looking deeper into it I just can't see the architecture.

You're not alone here as that's the view of every advocate of SSTO in any form I've ever talked to :)

The engine has always been only part of the equation and more often than not it's not even the biggest part thereof. And neither in fact is the structure, or method, or... Whatever. It has always been about the whole rather than individual parts that are used and quite often the most efficient use is non-intuitive, especially when there are basic bias' and assumptions involved.

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Not going the whole way in a single stage suggests but you are using SABRE suggests you're OK with the engine but don't believe the structure.

Actually I'm agnostic about it and always have been, what I'm arguing is that assuming you know all the facts that are required 'solve' the equation before they are actually facts rather than assumptions, suppositions, and/or theory is a bit premature :)

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The only large reusable high Mach structures I know are the Shuttle, the X37b, X15 and XB70. Except the X37b all have done powered flight inside the atmosphere but only the Shuttle did the whole potential SABRE speed range and only the XB70 could lift its own weight.

The X-37B actually does the whole range on the way back down, also Buran did the regime as well so you need to expand your examples :) Further "lifting its own weight" is a false argument, that's the engine not the airframe and the XB-70 did not in fact have a T/W of less than 1 at lift off. (You're also forgetting the SR-70 and B-58 both of which flew as fast as the XB-70 at times) You are trying to compare vehicles with vastly different designed missions and objectives as 'examples' of something which actually has nothing to do with the basic discussion.

Lastly how does it matter? None of the cited examples are or were optimized as multi-mach carrier vehicles with exo-atmospheric staging capabilities or single-stage-to-orbit vehicles so are you suggesting that because of those examples both Skylon and any type-of air-breathing, multi-stage vehicle are impossible? That'd be a rather funny argument don't you think?

Skylon is both bigger and heavier than the XB-70, it is meant to fly about as fast in the atmosphere as the X-15, (and around the speed at which that specifically designed vehicle was damaged severely) and into space and back bearing a payload less than the Shuttle's to a lower orbit. All in a single stage at greater economy than any possible other design. Or at least that seems to be the main point of contention :)

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If you're that nervous only a rocket would be acceptably safe for the 2nd stage.

No idea where you got this particular 'issue' from or what it's based on but then again, so what? Why is a rocket powered seconds stage NOT acceptable? Oh and try to keep YOUR bias' and assumptions out of the equation where they are not specified or required ok? :) (See below)

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It's this mix of optimism and caution that I'm having trouble with.

Yep and that IS your 'trouble' and not anything to do with the discussion :)

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So an LH2 powered engine is OK.

An LH2 powered air-breathing engine capable of operation from zero to high-mach/low-hypersonic speeds? Yep. Can't see a single reason why they wouldn't be as they have been tested and studied since the mid-50s and shown to be workable and practical though no one has actually used one in operation yet.

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A truss structure with fibre reinforced glass skin is not OK.

That's your assumption of something that wasn't said or indicated in any way, but specifically in my opinion it's perfectly acceptable IF that is where the actual, (and not simple) trades go. So far no one has actually gone beyond the simple trades.

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Horizontal separation at high Mach number (that's an assumption but I've hear nothing about a VTO SABRE concept) is OK.

Actually I have in fact suggested that VTO SABRE is possible as you keep noting the T/W is sufficient for the job :)

Horizontal separation at "high-mach" numbers has in fact been done before, successfully. The B-58 was in fact designed around the concept. There are some design and operations factors to take into account but nothing that precludes the operation.

But lets be clear that any 'issue' of doing so is based on your assumptions rather than anything brought up in this discussion because that IS the very heart of your argument with the idea.

YOU keep assuming that (for some strange reason) any SABRE powered first stage must separate from its upper stage at high-mach INSIDE the atmosphere when the SABRE is perfectly capable of powering that same first stage on an exo-atmospheric path using the inherent rocket engines in it along with on-board oxidizer to achieve that trajectory.

Why? Because, I suspect, like most SSTO advocates it is difficult to imagine that if it's 'possible' to go from Mach-5 to Mach-20 using the same engine, airframe, and systems then why would you even imagine trying NOT to do so. The rather simple answer is because reality very often does not conform to what we might wish it to be but rather we most often have to conform to what reality is. Skylon's numbers are 'conservative' but are based on estimations and assumptions rather than actual numbers from research and construction data. They could be spot-on but the most conservative assumption would be they are in fact low by a good margin. Why? Because no one has built something like Skylon for operational use and neither REL nor anyone else can in fact truly state those at this point.

They have a lot of estimates that may or may not end up being accurate but at this point that is all they are and treating them as objective facts misuses the whole process.

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True. I'd never really thought of Skylon's design being selected because it was easy to anlayse. It seemed to address quite a few problems.  I don't know about "optimum" but I'd certainly say "Good enough" and given the design goals I think it would be difficult to come up with something that looked much different but still gave undisturbed airflow to the engines and a well balanced design.

It's a cylinder with wings, with engines on the wing-tips to keep them out of the airframe flow equations. It is in fat about THE easiest theoretical shape to provide analysis on. Pretty much the same design Kelly Johnson started with it for what eventually became the SR-71 and for the same reasons. It 'solves' various problems by not addressing them therefore giving you a very basic idea of the requirements without resorting to far more complex, (and accurate) mathematical models. It gets you to "good-enough" for some basic design work but is about as close to an operational design as the CL-400 was to the SR-71 and for many of the same reasons. And I'll point out that the 'design goals' specifically are to have something that you can use to estimate the overall performance of the SABRE from using estimated performance of the SABRE itself. Everything from that point is estimates on top of assumptions rather than anything one could consider either a 'design' or a 'goal' in and of itself.

Lets be clear here, engine performance can be enhanced from 10% to 30% by optimizing the air-flow using the forward and aft airframe for pre-compression and expansion purposes. Controllability and stability can be highly improved by moving the engines from the wing-tips to positions closer to the airframe. Propellant feeding and flow would be far less complex with the engines within the airframe especially at high mach speeds. Airframe and wing stress' and manufacturing complexity are higher with the engines on the wing-tips as opposed to integrated within the airframe. There are high and low speed issues along with manufacturing and operational areas that could be addressed by a different, more integrated airframe and engine assembly.

Those are the most obvious 'issues' that the Skylon design ignores in order to simplify the equations and that is fine at this stage of the overall design process. But it is no where near a finished product and should not be treated as such.

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AFAIK the perceived advantages are an easier design problem as your design is split in two and you can have more structure and a higher payload fraction.

But Skylon was designed to deliver an ELV payload fraction, not the 1% of the Shuttle. For an equal payload I find it very hard to believe a TSTO will be simpler to design, build or test.  I doubt it would be cheaper to operate either.  The big question is the perception of how risky is the Skylon structural design.

It's more than a perceived advantage and it's more than just about the delivered payload fraction. You may find it hard to believe but it is in fact something that is well understood in the aerospace industry. Yes if all factors are equal an SSTO would in fact be both economically and overall cheaper to build and operate but the plain truth is all factors are NOT equal. They never have been and while that may change at some future date, neither SABRE nor Skylon has enough actual performance facts to make the assumption they will do so.

Once SABRE has some actual performance data and Skylon is far better defined there might be reason to change, probably if either ends up coming in close to promises but then again maybe not as there are a lot of factors in play. And a vast majority of those 'factors' are at this point guess' and estimations because no one has yet built a fully reusable space launch vehicle of any type. A lot of those estimations are built upon rather shaky logic in fact as they tend to use known quantities from other forms of transportation as factors on which to base those estimations in ways that may not in fact be actually applicable to space transportation.

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I know you hate the launch-vehicle-like-an-aircraft analogy but no one has ever built a large 2 stage cargo aircraft, despite the benefits of an enormous 1st stage to get a heavily loaded (and fueled) 2nd stage off the runway and airborne.

As Paul451 points out that's not really the case but more to the point the main reason I hate the analogy is because it's simply false from the basic premises. It is in fact constantly used wrong and the conclusions drawn are false and highly misleading.

NO TRANSPORTATION SYSTEM ON EARTH IS LIKE SPACEFLIGHT! Simply can't say that enough. No one has ever really NEEDED to build a "2-stage" aircraft (ship, train, automobile, whatever) because they could always find an intermediate place to 'stop' along the way. You can't do that between the surface and Earth orbit and the closest analogy is using multi-stage vehicles to reach Earth orbit. Full stop.

In fact lets take that too-often over used analog and spin it into the ground hard enough to leave a crater visible from orbit shall we :) Going from Earth to orbit and back using an aviation analogy is like taking off from New York and, no crossing the Atlantic isn't even close, crossing the Pacific non-stop is barely in the ball-park, no what you want to imagine is going all the way around the world, non-stop, non-refueled, and landing again in New York. (Oh and don't forget to kick the passengers/payload out of the plane half way around the world without landing because that would be cheating)

The simple fact is no one has EVER built a single-stage-to-destination long distance vehicle that operates on a regular, commercial basis in ANY form of transportation on Earth because we've never had any reason to do so. We've built some one-offs and some very expensive, limited use, government vehicles that are capable of some portion of that for specific reasons but we don't use them commercially because they are in fact not economic for any purpose other than the very specific one they are used for. No one builds them otherwise because we have never needed to.

It sucks but the simple fact is we HAVE to do so to access space because there IS no place to stop in between. And in doing so, if we ever can do so on a regular basis, will not only change the way we do things in space it will in fact require that we fundamentally change the way we do things in space. (Trust me that is WAY deeper than it looks and far to much to get into here :) )
 
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If the design assumptions on Skylon are as conservative as you think that seems unlikely barring (again) the perception that HTOL SSTO  is risky and would essentially put the airframer at square 1 in design.

1) The 'design' assumptions on Skylon are quite conservative given the assumptions they are based on. Note they are based on assumptions from the start so 'conservative' is very relative in that context.

2) While not on square 1 any airframe developer is going to take into consideration what REL has done but they are going to be fully aware that unless every single item of the "design" of Skylon is absolutely on-target to several dozen decimal places the fact remains that no one at REL is in fact an airframe or aerodynamics specialist. So while they may take the same factors into consideration that REL used to arrive at the Skylon design but more likely they won't because they actually do know what they are doing and will not have the same bias' and assumptions involved that REL did.

3) You need to understand that ANY SSTO is "risky" due to numerous factors, some of which REL not only did not consider they specifically ignored in order to arrive at the Skylon "design" as it is. That's ok, they are not after all airframe designers and for what they need the Skylon "design" for they do not need to consider the overall vehicle in that kind of detail. On top of those there are manufacturing and operational details that REL is not qualified to detail because they in fact do not know all those details, nor do they pretend to know them. They have made some qualified assumptions in order to "close" the overall design in a method that allows them to carry out the calculations they need to carry out. They are not meant to be taken as literal and as far as I can see no actual manufacture or possible operator have taken them as such. Here seems to be the only place they are taken as gospel and for general discussion they actually perform satisfactorily but only as long as you keep in mind they are in fact assumed factors rather than actual ones and don't take them too far.

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An interesting point. NASA pointed out that SABRE plume heating of the rear fuselage might be an issue, but did you have any others in mind?

Really nothing specific because the design isn't at a stage to get seriously picky yet. "This is a basic design of a vehicle that could possibly perform this mission with calculated thispayload using the SABRE engine with a performance of this assuming these parameters" pretty standard low-res data-sets and estimates overall. But in particular when someone with more expertise says there might be a problem it behooves you to take them seriously. There is room for tons of improvement from the current "design" which is to be expected at the current stage that "design" is in. But the mathematical models and calculations increase along the way which is something REL pretty obviously doesn't want to spend to much time or money on doing since they aren't an airframe designer. Once they have a partnership with an airframe designer who's working towards an actual vehicle design they will both put a lot more effort into working together to finalize and refine everything towards whatever design goals that eventually emerge from the trades.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: SICA Design on 08/16/2016 07:03 PM
Ranulf, I'll pick on a tiny bit of this novel you've written  :)

GTO was in fact the MAIN mission of the EELV not delivery to LEO which arguably is the main mission of the Skylon design as that's what it's designed to do.

...by re-quoting Hempsell from 'Thread 4 giving JS19 a jolly-good ticking off  :) :

...a whole range of mission requirements were considered and the one that drove all the sizing and mass constraints was launching a comsat on a cryogenic stage.  NOT because that was given a priority but because it needed the most, and everything else could live with less.  I am sorry John Smith 19 RanulfC you keep assuming comsats were the “primary mission” they weren’t, they were just the driving mission among a set of equals.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 08/16/2016 11:01 PM
TBH I sincerely hope so.  :). I just can't figure out where they want to draw the line that gives you a much better system.  The known  SoA for powered flight is the X15 but that was designed to operate long enough to soak the whole airframe.  I think you could use the same materials (since materials and structure would seem to be the the concern here) to build a SABRE powered 1st stage to go to the X15's top speed.  This would have major implications for the size and payload of any 2nd stage.

Actually the original construction of the X-15s was only for a bit above Mach-5 and as noted it was a different structure than anything anyone would consider using today mostly due to the expense and difficulty of maintaining that same structure over 200 flights. (Quick search didn't find it but I know it's been posted on the forums before. There was a very interesting study using the X-15 as a "comparable" vehicle for a recoverable first stage. It wasn't complimentary which was unexpected I understand :) )

Thing is it's right because the X-15 was specifically designed to test out high-speed aeroheating soaking but because there wasn't enough information, (duh, that's what the X-15 was for after all :) ) the design, materials and construction left a lot to be desired even in a test vehicle. And going past Mach-5.5 required re-building the basic airframe and the addition of ablative protection and even then there was damage.

The thing is we DID learn from the X-15 and we are well aware that it's design was limited, it's materials were not optimum, and it's construction was difficult to maintain and too prone to damage or failure under severe stress. Really we have much better designs, materials and construction methods if we want an effective, robust hypersonic vehicle. Getting someone to actually pay to build one now that's a different matter :)

But I'll point out that an effective hypersonic design is one that avoids the X-15, (Skylon for that matter) "fuselage and wings" design and the faster you go the more you want an integrated vehicle design overall. Mach-5 is pretty much the limit of that design which I suspect is one reason REL set that as a cut-off. Around Mach-6ish you want to have more body lift and the less "wing" area in the air-stream the better. That and combined low-speed and high speed aerodynamics is why you tend to see 'wide' body vehicles with small wings for hypersonic designs.

As hypersonic designs go the X-15 is terrible and the main baseline designs tend towards shapes like the X-24B/C, and NASP-ish/X-51-ish wide-body designs though there are alternatives even there.

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Care to expand on that? IMHO the economic model is every bit as important as the thermal cycle model.

Not much to expand on really as the economic model is pretty simple overall except being based on an aircraft, (technically it would be more accurate to describe is as "any transportation system OTHER than spacecraft/launch vehicles" model but... :) ) model rather than a standard spacecraft/launch vehicle model. It has to be because none of the figures can be directly tied to actual data for the SABRE or Skylon because no such data exists. That doesn't mean you can't get some general numbers and as long as everyone keeps in mind the various assumptions in the models the basic output is good for a low-res, first-order outcome.

Probably the main sticking point though is it IS based a lot on aircraft economic modeling and like many other uses of "aircraft" as "spacecraft" there's some basic issues with using a lot of that data without qualification.

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That's my point. People know this is an issue yet insist on designing vehicles that will have problems and then complain they can't get the design to work.

That's actually not a very valid point though because in fact no one does design vehicles with those problems because they know about them. HOTOL would be an example of that but that was BECAUSE the people designing it were unaware of some or all those issues. Did you have something else in mind because as far as I know that hasn't been an actual problem in any other vehicle design I'm aware of.
 
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I think NASA was going to do one of these with the engines half way up the body.  Given that they've flagged plume impingement as a potential issue on Skylon I could not see how they'd avoid the rear fuselage getting quite "toasty."

They don't, no one does in anything past a first-order airframe design. The impingement is part of the engine exhaust system design and is dealt with by propellant circulation cooling along with fore-body pre-compression and airstream cooling in front of the inlets. It's not a problem if you design for it in the first place and the added efficiency is well worth the complexity over non-integrated engines. REL didn't bother with Skylon not because their set up is more efficient in any way, it's just easier to model the set up they have.

REL doesn't address impingement at all in the Skylon design because it would require a higher order of modeling which they don't need at the resolution they are using.

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That's certainly been historically true. Manual tracking of part masses meant recalculating a new empty mass would be a major exercise.  But with BoM properties in a database (or at this level of fidelity a set of spreadsheets) propagating a part mass change through the design (although not the change on the mass of associated parts) should take seconds, giving an early warning that other part will need to be re-designed or re weighted.

No the properties data-bases themselves are low fidelity because each installation is different. Sometime only a little, sometimes a lot and changes in parts mass have a LOT of follow-on effects that low-order fidelity formula don't show. The fidelity is much higher once you have actual rather than inferred data to work with but at the moment low-order, low-fidelity numbers work for the design resolution involved. Nothing REL is using is more than a first-order fidelity at this point because they don't in fact have significant detailed data to work with, they have general number to plug into the data bases and get general results.
 
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REL treated Skylon  as aircraft, so they applied aircraft margins.

Yes and that's not as "good" a thing as many seem to think. Skylon isn't an aircraft and many of the margins that apply to aircraft ONLY apply to Skylon in very limited and specific instances with many more equaling spacecraft and hypersonic aircraft margins. Neither of which is easy to calculate without direct data. Any spacecraft can in fact be treated as an 'aircraft' in some very basic formula work, it's a staple of most SSTO concept work for low-resolution concepts but once you move beyond the simple calculations you get more and more spacecraft data rather than aircraft. Aircraft data doesn't even work very well for economic models due to significant operational differences.

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With the proviso we're talking VTO TSTO rockets.

Not really as part of the summery notes that it applies to, and from the aircraft industry as well. And specifically SSTO designs (both HT and VT) are mentioned as being effected. The paper is aimed specifically at mass growth in the Exploration Architecture but the general trending is historical over many different concepts and types. There is no indication that Skylon or SABRE would be immune from it and every reason to believe it will be effected.

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REL have been very careful to work with industry standard methods so that anyone looking over their work (like potential investors) can follow the trail from objectives back to how they are going to be carried out. Sadly these include the cost models that predicted SX would have to have spent about $2Bn up to the first F9 flight, but they are the industry standard.  :(

So? The main issue is that what REL has done is not as high fidelity as is being assumed by many outsiders. Potential investors are not buying into Skylon, not directly because what REL has is not in any way to the point where it is realistic enough for investment on the level of actually building an airframe. It can't be because everything depends on the engines and until those are tested and actual data in-hand actual airframe design work can not proceed to a second-order concept and actual trade studies begin. How accurate or not their cost models for SX are in irrelevant, and actually they tend to cause conflicts over trivial issues as we're all aware.

Currently there is no real 'trail' for anyone to follow other than seeing how accurately REL has kept records of it's intakes and expenditures to reach this point in time. That gives some investors some confidence in RELs record keeping and budgetary process but it really doesn't begin to become relevant until they start full-up engine testing and begin defining a flight-capable/weight engine at which point they will actually have something to seriously interest investors. Skylon at this point is nothing more than a low-res concept with almost no relevance beyond some very simple calculation work on a possible end item to use the SABER engine.

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That ability to absorb mass growth would seem to be the virtue of those giant Philip Bono 1960's designs, although drag is a problem if you're going with the idea of a "micro launcher." so somewhere in between seems to be minimum trouble.

It was touted as such but if you get into the details the problem was they HAD to be big and they still rapidly lost payload capability with mass over-runs or less efficiency than predicted. The problem is that in aerospace vehicle design smaller is ALWAYS cheaper BUT the devil is in the details :) The current spate of micro-launchers is pretty much based on industry and private reports of a high interest in nano/micro/small satellites by what's considered "non-standard" (non-government/non-sat-industry users) that could be a opening for enlarging the market. Significantly.

The main problem is, (other than it's pretty OT since I can't see Skylon or SABRE being downsized that much even though it would help in many, many ways :) ) that there's a good number of start-ups in progress and most of them are seeking not only the same market but a lot of the same funding. The fact that both government and "industry" have both announced and then canceled similar systems hasn't helped investor confidence either and that actually flows all the way to effect things like REL.

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I'd point out that REL (as Hempsell said) sized Skylon to do a comm sat mission to orbit. Historically they assumed that the payload would carry it's own engine to handle GTO. Other payloads to LEO would then be free to use the payload for that stage for their own uses. Note it's the end users issue to get such a stage.  ESA advised them offering an upper stage would make the system more flexible, and now it's in the development plan.

And that was the initial mistake which as corrected by expert advice :) And anyone who really understood the nature of the Comm-Sat market would not have made that simple mistake because the payload NEVER provides it's own way to finish the job. That is specifically what the customer is paying the launcher to do, it's an issue the "end-user" neither wants nor technically needs to deal with. And not having that capability means you're not seriously interested in servicing that customer OR his market. Hence the ESA advice.

Hempsell or someone from the initial group should have know that but they were like most SSTO advocates which tend to have a significant blind spot to the "orbit-is-not-the-destination" problem with SSTO vehicles. LEO payloads are actually a bit more of a market than when REL first started up but that's not an excuse, that's a lucky break and it's still not the "comm-sat" market that was initially aimed for so it's a VERY big beginning mistake to have made. (No the SUS has not in fact made up for it either :) )

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Looking back it's a question of where you draw line on the stages maximum trajectory. Skylon's "first" stage gets you to orbit (which can be up to 600Km) , which for a lot of Earth Observation payloads would be enough. All other LV get you to maybe M10, but typically their 2nd stage can get you to GTO or even escape. A fairer comparison would be a TSTO just to LEO, then a third stage for anything about that.

Eh no, looking back it's obvious that the initial concept of Skylon was not directed either at the supposed 'customer' it was advertised as serving nor is it doing so today and in order to correct that mistake a second stage, (one being designed outside REL which is both good and bad from a customers point of view) is being designed and built. You also can't 'compare' a TSTO just to LEO because Skylon still looses and you don't want to make the loss any worse than it already is. The specific TSTO that Skylon was designed against was an EELV which still delivers MORE payload "just" to LEO than Skylon and can then, without major changes or another stage deliver equivalent payload to GTO and beyond.

Changing the rules by insisting that adding a "third" stage to the TSTO simply shows how badly Hempsell and REL initially failed to address the market they said they were initially aiming for. An EELV can already do it and a well designed fully reusable TSTO could do it as well using only two, not three stages. Skylon can serve a limited market that has only become a viable market SINCE it was suggested and not even the one it was advertised as serving. In order to serve the market is was originally advertised to serve it requires two stages and not leaving that to the customer. That's something REL has to live with and so do Skylons advocates.

It's not a horrible sin mind you, but it's most certainly a failure to see and address the actual market and conditions from the start.

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A Skylon "first stage" is useful on its own. No other first stage is, unless people were prepared to do significant redesign and take a major cut in payload.

First of all no it isn't. A Skylon "first-stage' has no real use as it doesn't exits yet. It has possible uses by itself if and when it has performance and manufacturing data and could, once in operation significantly change the way humanity access space. But it is only potential at the moment and has just as much chance of never going into operation at all. Meanwhile a functional and useful reusable first stage already exists with many of the same opportunities and more than a few drawback but in no way can you claim that no such stage exists.

Lets not get carried away with they hyperbole in the rush to advocate shall we? :)

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Actually I checked my posts and have not called it stupid. I just could not see why you would. It seemed a "sub optimal"  to me. I can now see that an argument can be made but I've also recalled this came up with the question of how much a Skylon could carry sub orbitally. REL reckoned it was 2x their payload to orbit but the separation was quite risky and the payload would need something like 100-1500m/s (IIRC). Hempsell said they discontinued modelling on it as no one seemed that interested and you'd still need to build a Skylon to do it.

Well just because you, REL and Hempsell have lack of imagination... :) See the thing was while REL was making assumptions you needed Skylon, and the separation maneuver was risky, the simple fact was they never considered using anything BUT Skylon in the first place and their separation maneuver WAS risky because they were using Skylon, not because of the maneuver or process itself.

Stop trying to justify only using Skylon by only using Skylon and things are quite different, and the reason you would is quite plain actually. "2X times the payload of a standard Skylon flight to orbit" is a good start but as I recall the impulse needed was carried as part of the released mass but it was not if fact part of that "2X" payload mass which is part of the reason REL dropped it in the first place. Once you got past the strawman of using the Skylon itself for such a non-optimal use, (yes I very much agree that it wouldn't be what you want to use for first stage carrier vehicle, not odd at all as it's a very limited and point-design vehicle that has limited uses beyond it's primary job) and building in the staging maneuver without the restrictions and limitations that REL had in the scenario and you end up with much more 'bang' for your buck(s).

But again this all goes back to what Skylon was initially designed for and not any shortcoming with the SABRE itself.

 
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That's not quite correct.

No it's actually quite correct because you have some serious blinders because of bias' and assumptions which I keep pointing out :)

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Pure rocket could do it if you can get the structural mass down, and that seems very tough.

It IS tough and no SSTO advocate would argue that it isn't but it is far from impossible. Accept the limitations and you're fine. For one thing get over a fixation with LH2, (which has been difficult even for people who actually knew better but were blinded-by-the-light as it were :) ) and embrace alternatives you get much closer, much faster but there are limitations.

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Anything needing deep pre cooling prior to REL's work I'm very doubtful about due to frost control and anything air breathing will need to have good air breathing Isp to swallow the loss in T/W.

Sorry more than one researcher working the "Aerospaceplane" in the mid-50s solved the frost problem and in more than one way as well. They considered it a non-issue and it's not their fault that REL didn't know about it the fact that it WAS solved was well documented. Air-breathing ISP and T/W are interchangeable by a number of well known and proven methods the big sticking point in most research was the "liquid-air" trap which along with SCramjets ate up all the research funding and effort for far to long. An air-breathing rocket was understood in the 1950s the only problem was the afore mentioned "liquid-air" side-track and while the actual deep-cooling effect was known it was lost in the data noise unfortunately. Patent's were taken out in the mid-90s in the US on a couple of deep-cooled air-breathing rockets using RL10s but no one ever was able to get funding to go beyond low-res concept work.

And that of course assumes that deep-cooling is really the end-all, be-all REL claims it is which is questionable as an assumption since there are methods of reaching Mach-5 without it and with pretty normal turbo-machinery. LOx injection makes a rather crappy rocket from an afterburner but it works well enough to allow exo-atmospheric staging possible if you don't want to carry a separate rocket system. In the end it comes down to trades as long as you're not too deeply invested in bias' and assumptions.

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Anything that air breathing and  VTO means very low structural weight x (relatively) low T/W --> unlikely despite high AB Isp.

Depends really there were some pretty high T/W and isp engine systems developed. SERJ had a higher T/W and ISP than SABRE in LH2 systems (and no frost problems) and MUCH higher T/W (and middling but still SSTO possible) isp with Peroxide and jet fuel. VTVL TSTO was better in just about every aspect but like many concepts the designer got caught up in the liquid-air and SCramjet craze and separating out those aspects is more work than most current designers are willing to do for a system that was designed and tested almost 60 years ago.
 
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Not stupid, just seemed an odd idea.

Not really and if you'd like to show exactly how any part of it is "odd" without resorting to requiring the Skylon as a vehicle feel free but I'm pretty sure without that last it won't seem as "odd" as it would seem :)

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I'd be wary of that. Their work on E/D nozzle design (and improvement) and work on the inlets suggests they either have hypersonic experience on staff or access through partner companies.

Not at all really, it's the other way around. Again the Skylon as designed is the way it is to limit airframe airflow interaction with the nacelles and vice versa. This is so that limited and simple airflow calculations can be used on both the airframe and the nacelles. This requires work for calculation of the nozzle and inlet performance to be separate from that for the airframe which also requires very different and complex inlets and nozzles. Their work on improvement of both is because the Skylon design is not optimized and because they do not have the relevant skillsets and knowledge to do so. (Or don't want to which amounts to the same thing in general practice)

That they are getting some help from outside is obvious as they didn't significantly advance on the E/D nozzles until after RR joined up but so far we've seen nothing that wasn't already done along those line in previous work. Again this stuff is only to achieve clearer numbers on the engine performance OUTSIDE of any airframe interference which is REL's goal but not that of someone who is designing an air-breathing hypersonic airframe for a spacecraft.

REL has chosen to avoid as many problems as possible and a equal number of advantages in order to simplify their calculations on the operation of the SABRE by putting the engines where they are and designing the minimum airframe needed to have the needed figures for doing so. That in no way translates into it being the "right" answer at all.

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Which is pretty much SOP for all engineering projects, establishing that a design is possible if "Component X" can deliver these specs.

Correct but it is never anything BUT a first-order concept at that point because "Component X" is plugged into the simple spreadsheets and formula but not actually integrated with all the necessary support and structural factors figured in. At this point you're only worried about the general placement and listed operation but you have not yet actually done any of the really hard work of integration and design. The design is "possible" only in general at this point without enough form and data to do more than estimate performance and capability. Which is fine but very far from something you can actually prove will do what you say it will.
 
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True, and a bit of a chicken and egg situation. Hopefully BAE will be able to provide some "sanity checking,"  although I would have expected the ESTECH  to identify any issues like this already.

Many people assume that ESTECH did just that but what they ended up with is basically; "If all assumptions and calculations are valid then we see nothing in the given figures that will not work as planned" They wouldn't have actually followed up with in-depth research on each and every assumption or calculation to a degree much better than REL has done since that's not what they were asked. The "chicken/egg" at the heart of the whole concept is a working SABRE within parameters or at least nearly but no one can know how close everything else is until that data is available.
 
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I did not know it was that high.  But remember the old rule of software development
"Optimization is the root of most evil."

That CAN be true of any type of project but you HAVE to make compromises or you end up falling short. Skylon is not optimized AT ALL and was purposely done that way so that REL would not have to do more work on the actual vehicle than they needed to arrive at some basic figures.

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IIRC In the X30 programme "complexity in airframe thermal management" meant a)Building large chunks of design in RCC or b) going with active cooling.  AFAIK Skylon aims to make very limited use of either.

X30 is ALWAYS a bad example :) But, they were using RCC and active cooling because they were flying somewhere between Mach-8 and Mach-10 inside the atmosphere with NO other propulsion than air-breathing and they had to actually stay pretty low to make it work with such a small vehicle. The actual NASP was supposed to fly both higher AND faster but the X30 couldn't due to it's size. Active cooling is often ignored simple designs because it's seen as complex and a failure point. A bit true on both but Skylon actually uses it at well since the LH2 cools the wings as it flows to the engines and is circulated in the engines to keep the structure cool before being burned.

Skylon's not advertising it's use because it's a simple design but it's there anyway. Again the Skylon is designed to avoid airframe/engine interaction and not to be really good for air-breathing hypersonic flight even in a limited amount. It works but it's far from the best design.

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Everything has a price. Is that increased efficiency a) Affordable b) Needed ? NASP needed it with an engine  T/W ratio of 2:1 but does SABRE?

Actually NASP started off with a T/W of something like 10+:1 at take off which went down as it ramped up to using SCramjets. Deep-cooling really boosts the T/W early in the flight. And IIRC no one ever admitted that the SCramjets were going to be less than at least "2 or more to 1" in any official papers despite that not being shown in any test data :)

Is it affordable? That depends on what the trades come up with but in general the current design of Skylon has NOT traded well over a more integrated design and REL is the only one using it. (Again that's for a very specific reason and one that has very little to do with performance and a lot to do with simplicity in many other areas) Does SABRE need it? Who knows since there is exactly zero actual data on SABRE performance. To put it mildly in the end SABRE DOES need it no matter what it's performance because any and all added performance only enhances it and opens up more possible benefits.

REL is actually causing some issue since they are so fixated with the nacelle/pod design and it's causing many people to wonder if the SABRE can in fact only be used in that configuration. ((Which I don't see as it does not in fact appear to have that issue to me though some folks I've talked to have brought it up)
Pod/nacelle designs have always had significant issues with use in hypersonic aerodynamics which is why most advanced designs do not use them. As far as I can tell most people who understand what REL is doing and why grasp the reasons and do not hold that against them but enough people have brought it up, along with other issues of Skylon as is being THE design, that I thought I should try and make it clear WHY REL has done what it's done and why Skylon is a good start but only a start.

In general I'm guessing I'm failing miserably :)

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The inverse problem is IMHO trickier. Ensuring any improvement in a subset of the flight envelope does not make other parts of the envelope worse to the point the design won't work. A TSTO would open up options at the cost of designing 2 vehicles to do so.

Probably not as even at a higher cost it will probably be significantly easier and in the long run cheaper to optimize for each segment of the flight rather than the whole flight. Often the problem with SSTO is that due to optimization for the whole flight it IS certain segments of the flight where larger (and expensive) problems crop up. They key is designing smarter not harder but you have to really get into the design to find out which is which. Skylon isn't there yet by a long shot.
 
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With that staging velocity you could consider a very conventional expendable liquid upper stage. One notion I've wondered about would be wrapping 2 half circular wings rounds such a stage on pivoting on a structure like a piano hinge with some kind of "aerospike" or "aerodisk" to improve the aerodynamics of the flat front end. Such an empty stage should begin  entry at a very high altitude, but again has all the issues of being back end heavy of the shuttle without it's control surfaces.

Well what kind of upper-stage to use is very much a function of mission and design trades but I was going to point out that one very 'nifty' side benefit of an optimized "high-hypersonic/space" stage could be the ability to perform plane changes with very little propellant using aerodynamic steering. Which in and of itself has all sorts of "multipliers" even if, (Ok especially if) you only use it with something like the 'nominal' Skylon. (Easier and more effective with a TSTO but I'll throw that out there anyway :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 08/16/2016 11:17 PM
Ranulf, I'll pick on a tiny bit of this novel you've written  :)

But what about the character development? The chase scene? Nothing about the unified field theory? Oh well, I tried ;)
Quote
GTO was in fact the MAIN mission of the EELV not delivery to LEO which arguably is the main mission of the Skylon design as that's what it's designed to do.

...by re-quoting Hempsell from 'Thread 4 giving JS19 a jolly-good ticking off  :) :

...a whole range of mission requirements were considered and the one that drove all the sizing and mass constraints was launching a comsat on a cryogenic stage.  NOT because that was given a priority but because it needed the most, and everything else could live with less.  I am sorry John Smith 19 RanulfC you keep assuming comsats were the “primary mission” they weren’t, they were just the driving mission among a set of equals.

But that's NOT in fact what has been said constantly about what drove it AND while I understand the actual context of what drove the design along with what REL (and Mr. Hempsell) have been aiming at from the start, if that were the case they really should never have mentioned ELV and Comm-Sats at all.

I really DO understand what the 'equals' were that were being considered as they are obvious, SSTO was and remains the "main" force of what REL is trying to accomplish with SABRE if not Skylon but the rather threadbare fact that what is driving and has driven the design of Skylon and SABRE. To the point where REL has removed any mention of anything BUT SSTO operations in order to avoid the discussion. And while that simplifies things for them, (I'm sensing a pattern here :) ) it doesn't help that it avoids and does not address the actual issues of the design, the concept and their goals.

SSTO is in fact a goal worth striving for but as an engine manufacture and not an airframe designer from the start REL is going to have to face the fact they may not in fact get exactly what they want or deliver everything they think they can.

Thanks for reading though :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Hanelyp on 08/18/2016 07:59 PM
Lets be clear here, engine performance can be enhanced from 10% to 30% by optimizing the air-flow using the forward and aft airframe for pre-compression and expansion purposes. Controllability and stability can be highly improved by moving the engines from the wing-tips to positions closer to the airframe. Propellant feeding and flow would be far less complex with the engines within the airframe especially at high mach speeds. Airframe and wing stress' and manufacturing complexity are higher with the engines on the wing-tips as opposed to integrated within the airframe. There are high and low speed issues along with manufacturing and operational areas that could be addressed by a different, more integrated airframe and engine assembly.
Sounds like making the engines integrated with the airframe for airflow can improve practically everything except ease of analysis and aft-body heating.  Might even increase the speed the engines can practically breath air a couple Mach factors.  But first prove the engine works as well as projected, then worry about an optimal installation.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Asteroza on 08/19/2016 12:32 AM
Lets be clear here, engine performance can be enhanced from 10% to 30% by optimizing the air-flow using the forward and aft airframe for pre-compression and expansion purposes. Controllability and stability can be highly improved by moving the engines from the wing-tips to positions closer to the airframe. Propellant feeding and flow would be far less complex with the engines within the airframe especially at high mach speeds. Airframe and wing stress' and manufacturing complexity are higher with the engines on the wing-tips as opposed to integrated within the airframe. There are high and low speed issues along with manufacturing and operational areas that could be addressed by a different, more integrated airframe and engine assembly.
Sounds like making the engines integrated with the airframe for airflow can improve practically everything except ease of analysis and aft-body heating.  Might even increase the speed the engines can practically breath air a couple Mach factors.  But first prove the engine works as well as projected, then worry about an optimal installation.

A good example of taking the spirit of skylon to one (of many) logical extremes would be sucking in the engines towards the center body and building the intake/nozzle ramps into the body sides (rather than the bottom), making something that looks like a flying axehead. Good illustration of that would SEI's Spiral-1/Sentinel design, in the following PDF on page 13-14.

http://www.sei.aero/eng/papers/uploads/archive/SEI_JANNAF_Sentinel_2007.pdf (http://www.sei.aero/eng/papers/uploads/archive/SEI_JANNAF_Sentinel_2007.pdf)

Flying axehead is a simplified approach to getting the aero-integration, but forebody sizing would definitely cause it to mutate due to inlet/forebody interactions if one were to chase a cylindrical nose design.

Bad idea of the day, if using an axehead design with the typical low wing aligned with the bottom of the axehead, would you have a usable busemann supersonic biplane effect if you also had a second wing aligned with the top of the axehead?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 08/19/2016 05:31 PM
Lets be clear here, engine performance can be enhanced from 10% to 30% by optimizing the air-flow using the forward and aft airframe for pre-compression and expansion purposes. Controllability and stability can be highly improved by moving the engines from the wing-tips to positions closer to the airframe. Propellant feeding and flow would be far less complex with the engines within the airframe especially at high mach speeds. Airframe and wing stress' and manufacturing complexity are higher with the engines on the wing-tips as opposed to integrated within the airframe. There are high and low speed issues along with manufacturing and operational areas that could be addressed by a different, more integrated airframe and engine assembly.
Sounds like making the engines integrated with the airframe for airflow can improve practically everything except ease of analysis and aft-body heating.  Might even increase the speed the engines can practically breath air a couple Mach factors.

Pretty much though as noted it makes figuring the engine performance alone really difficult which is why REL seems to have avoided it since the engine is in fact their main focus. :) As for the last part I have the impression that SABRE by itself has a pretty good Mach range (IIRC there was mention up to M-8 I think?) but the main question is how much you NEED to rather than what you can do since when you add in aerodynamic airframe heating at high hypersonic speeds it gets less viable without a huge amount of work. I think REL has struck a balance with picking the lower hypersonic end of things which many air-breathing advocates, (I'm looking at the SCramjet folks here :) ) overdo because they want to get the 'most' use out of the systems rather than looking at the entire mission objectively.

The long you use air-breathing the more complicated the whole vehicle gets not just the engines. And at it's most basic the SABRE and most other Combined Cycle Engines "solve" a different set of issues than just using atmosphere to power the engines. They get you from zero to hypersonic speed which for an air-breather and especially any horizontal lift design is huge advantage. Much beyond that, for space launch at any rate, you want to seriously consider getting up and out of the atmosphere which is where the Combined Cycles base on or incorporating rockets (such as SABRE) shine as they can do so while continuing to accelerate.

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But first prove the engine works as well as projected, then worry about an optimal installation.

Yep :)

A good example of taking the spirit of Skylon to one (of many) logical extremes would be sucking in the engines towards the center body and building the intake/nozzle ramps into the body sides (rather than the bottom), making something that looks like a flying axehead. Good illustration of that would SEI's Spiral-1/Sentinel design, in the following PDF on page 13-14.

http://www.sei.aero/eng/papers/uploads/archive/SEI_JANNAF_Sentinel_2007.pdf (http://www.sei.aero/eng/papers/uploads/archive/SEI_JANNAF_Sentinel_2007.pdf)

Flying axehead is a simplified approach to getting the aero-integration, but forebody sizing would definitely cause it to mutate due to inlet/forebody interactions if one were to chase a cylindrical nose design.

Nice, picked one of my favorites :) Just a couple of notes so we're clear; The Sentinel is a VTHL design so the wings can't support it for horizontal take off. Having said that you can see from the report that the take off T/W is rather crappy* and it's noted the design does "not benefit from augmentation below supersonic speed" which is exactly opposite of every ducted rocket, (which this engine starts out as) study results I've ever seen. Further the report actually calls out the design on the use of VTO with such a inefficient engine system.

Next the "axehead" (there's an official name for it somewhere I recall but that works for now :) ) design does not benefit from compression lift and external burning drag reduction in the exhaust stream like a design where the engines are located below the fuselage. At the same time it is far less sensitive to AoA to the airstream, but this goes both ways as a it does not benefit from positive AoA as other designs do.

But on the plus side it leaves both the top and bottom of the airframe more open and easier to incorporate things like landing gear and access systems without worrying about he engines, intakes, or exhausts.

*T/W at lift off for the study is 1.25:1 which is surprising as with an un-installed T/W of the engines being assumed between 20:1 to 35:1 for the type and specifically 27:1 for the study you'd assume a better total. Though SABRE is supposed to only have a T/W of 14:1 a big difference is that it has a much better integrated engine design than the "Independent Ramjet Stream/IRS," "Dual-Mode-SCramjet/DMSJ," and "Rocket" combined system base-lined in the study. This isn't surprising as the breakdown shows WAY the combined system is set up is directed to make the DMSJ the primary propulsion, (hello SCramjet research dollars) therefore the rockets have to be over-sized, (there's a development contract sent someone's way) and the "IRS" tacked on for... Well who knows really.

Problems with this set up abound with the DMSJ being only a small part of it, (for once not the main complaint :) ) but I'm still going to toss out that a SUB-sonic combustion ramjet will work up to Mach-8 so the actual justification for inclusion of ANY type of SCramjet is dubious to me. The "IRS" thing doesn't make sense to me as it appears to lack all the advantages of either an actual ramjet and an augmentation duct for a ducted rocket. The rocket system itself is very over-powered (despite the pathetic take off T/W it's bigger and more powerful than it needs to be BECAUSE of the VTO requirement) and while there are cases where physically removing the rocket system from an RBCC air stream have been argued, really it makes the design very much less efficient and the design of the ramjet much more difficult.

Maybe I should just point out that the AIRFRAME design is what I like not the concept itself? :)

Quote
Bad idea of the day, if using an axehead design with the typical low wing aligned with the bottom of the axehead, would you have a usable busemann supersonic biplane effect if you also had a second wing aligned with the top of the axehead?

Bad idea? Not really per se, the main question is what does it get you for whatever downsides there are in putting it into use :) With a Busemann Biplane the key to getting it to work well at more than just a single Mach number is having and keeping smooth airflow between the wings with a minimum, (preferably none) of disruptions to the flow. You'll note that most modern supersonic biplane designs have most of the "bulk" (fuselage, cargo, landing gear, engines sometimes though those are often between the wings as part of the separation structure but you will note they are set back from the leading edge of the wings) above or below the wings themselves to avoid their shockwaves.

To get the same effect with the axehead layout the wings would have to be pretty big. They would extend from in front to almost if not all the way to the aft of the vehicle and would include a number of electro-mechanical actuation systems to keep the air flow between the wings smooth. Make them "box" wings, (top one angled down, bottom one angled up and joined either by a vertical stabilizer surface or a structural joint) and you gain some low-speed advantages (more wing area with less actual wing, though how well this applies to a Busemann Biplane is questionable) with a stronger and more robust aero-surface area. Of course the wing-joint structures can be used to locate engines such as a couple of SABRE's so one wonders why you'd use the axehead airframe in that case and there is the basic question of how much compression you'd get from inside the wings and if the airframe and engine interaction would cause problems for the air-flow inside the wings. (My guess on those last two is, yes for the first but that that in and of itself would be highly problematical for the last)

To be honest I've heard of high-supersonic and hypersonic designs using something like "biplane" surfaces but they were in the context of using them to compress and act like high speed ramjets rather than actual lifting surfaces. So I don't really know if the idea would work, or even be practical in a general way. But I kind of like the idea for various possible designs. Now you've got me sketching out axehead airframes with paired trapezoidal (F-104 like) and delta box or joined wings, neat :)

Note: NASA/Glenn has a Turbine Based Combined Cycle simulator program here:
http://www.grc.nasa.gov/WWW/BGH/tbcc.html

I couldn't find one for Rocket Based Combined Cycle :(

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/19/2016 07:00 PM
I think REL has struck a balance with picking the lower hypersonic end of things which many air-breathing advocates, (I'm looking at the SCramjet folks here :) ) overdo because they want to get the 'most' use out of the systems rather than looking at the entire mission objectively.
In their 1989 Spaceflight article Bond said that was one of the key ideas behind SABRESkylon.  Not trying to hang on for just that last extra air breathing Mach number (and its associated friction heating) before shifting to rocket mode and going into a steep climb. It may also be the (rough) limit at which the design of the "spill ramjet," used to burn off the excess Hydrogen, starts to move into less grounded design areas. 
Quote
Maybe I should just point out that the AIRFRAME design is what I like not the concept itself? :)
When you wrote "This is one of my favourites" I was sort of wondering what part of it you favored.  :)
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 08/19/2016 08:54 PM
I think REL has struck a balance with picking the lower hypersonic end of things which many air-breathing advocates, (I'm looking at the SCramjet folks here :) ) overdo because they want to get the 'most' use out of the systems rather than looking at the entire mission objectively.
In their 1989 Spaceflight article Bond said that was one of the key ideas behind SABRESkylon.  Not trying to hang on for just that last extra air breathing Mach number (and its associated friction heating) before shifting to rocket mode and going into a steep climb. It may also be the (rough) limit at which the design of the "spill ramjet," used to burn off the excess Hydrogen, starts to move into less grounded design areas.

Wasn't the spill-ramjet dropped from the later designs? In any case there is a real issue of a loss of ramjet expertise over the last couple of decades from all the people and organizations that actually worked on physical rather than lab or theory ramjets. People who have done the research have shown that normal subsonic combustion ramjets are in fact a lot more capable than is generally believed, but the "common knowledge" today pretty much is that they don't work over Mach-5 and to go faster you have to have a SCramjet. Of course the "logic" from that point is if you're going to use a SCramjet you might as well get as much use out of it as you can, so...

The truth of course is different but between a lot of it still being classified, (which a lot of people don't understand since ramjets are 'obsolete' engines after all :) ) the general noise of the SCramjet advocates, and they die off of actual experienced people the knowledge is just vanishing at a frightening rate.

Quote
Quote
Maybe I should just point out that the AIRFRAME design is what I like not the concept itself? :)
When you wrote "This is one of my favourites" I was sort of wondering what part of it you favored.  :)

LoL,

Seriously for a non-body-compression lift design it's one of the better airframe concepts. (And it still actually manages to capture some good "body-lift" with the aft fuselage design when all is said and done)

It's actually a winged-body rather than the more often used lifting-body shape with minimal wings which is actually in some ways easier to manufacture and operate. (Something Skylon claims as well)

The wedge-shape gains much more capture area versus the overall vehicle wetted-area though it loses some body side compression in the process it's not as bad as most winged-bodies. (Skylon has far less but again it's base having as little interaction as possible from the start) This allows simpler variable compression inlets, probably not quite as simple as the under-body ramps but then again simpler than cone or nacelle's interacting with body and/or shock-on-lip compression. (Again Skylon avoids this by having the engines so far out on the wingtips, but in doing so also avoids all the advantages as well)

Overall it's got a better temperature distribution than normal winged-body or nacelle designs usually have which reduces the active cooling requirements significantly. (The Sentinel uses high-temp hydrocarbon in the form of JP-7 which is an operational assumption rather than an actual "requirement" so you can imagine how much better it would be with a cryo-propellant. And a non-REL related note the overall dimensions do NOT change if cryo-propane is used in place of the JP7 while they increase with methane and significantly so with LH2. Still I'd love to see a SABRE powered version done to the same fidelity. :) )

Things I don't like:
VTO. I understand the reasoning why, (mostly because it's an RBCC and Spiral 2, QuickSat as the TBCC was base-lined as the HTO vehicle which is biased in SO many ways from the start :) ) but it's really not needed for the overall design.

JP7 fuel. Again I understand why as the Air Force prefers "simple" hydrocarbon fuels but JP7 was designed and developed for the SR-71 and good lord JP10 is cheaper to use! If you have to use a hydrocarbon then seriously consider cryo-propane or methane. Heck I seem to recall a version of the QuickSat which used cryo-propane and no one batting an eye! In context I'd like to see this worked up with SABRE and LH2.

Partial exposure of the upper-stage/payload. Again I get the reasons but unlike the lifting-body vehicles there's a noticeable drag penalty for this in this design and fully burying it or fairing it over wouldn't have been that hard to fit in ONCE you got over some of the built-in flaws due to biased requirements.

Other than that, (and a few "peeves" here and there but that's more of those biased requirements than anything else) it actually is a favorite of mine for an air-breathing booster. The off-hand fact that you can, if you can ditch it intact that is, sail it into harbor like any other ship with a bow like that is totally coincidental I assure you :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Jim on 08/25/2016 10:35 AM
Way too early to consider that.  This thread is good enough for now.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Chris Bergin on 08/25/2016 09:30 PM

Would a  test vehicle qualify for a thread in
International Space Flight (ESA, Russia, China and others) > Other Launchers (Korean, Brazilian etc.) > BAE Valkyrie

or a part of a new sub-forum in
Commercial and US Government Launch Vehicles > BAE



While Jim doesn't speak for the site, I do. A new sub-forum requires at least 30-50 threads to be viable to be split into a standalone section and needs to show it will be creating numerous new threads as soon as that section is live. So this isn't a discussion for years.

No one will be happier if that actually does become a discussion we need to have, however!
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: 93143 on 08/26/2016 09:46 AM
Wasn't the spill-ramjet dropped from the later designs?

Don't think so.  SABRE 4 wastes a lot less hydrogen than SABRE 3, but I'm pretty sure it still uses more than the core can burn.

Quote
In any case there is a real issue of a loss of ramjet expertise over the last couple of decades from all the people and organizations that actually worked on physical rather than lab or theory ramjets.

I was under the impression REL had old-school ramjet expertise on staff.  I know Mark Hempsell has talked up the UK's extensive history with ramjets and referred to the conservative spill ramjet specifications as one of their "hidden margins".

Doesn't negate your point of course.  I had a discussion once on Talk-Polywell with a GW Johnson, who noted with dismay that he was "one of America's last surviving full-capability ramjet engineers"...
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Ravenger on 08/26/2016 11:32 AM
I believe Alan Bond once suggested that Skylon could fly on bypass burners alone if for some reason the main engines failed during a flight and the spaceplane needed to abort back to a landing strip.

Like any ramjet that can only happen if it's travelling fast enough for the burners to work, but it would increase the chance of returning the spacecraft and payload intact if engine problems occur in the air-breathing phase at high speed.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 08/26/2016 11:58 PM
Doesn't negate your point of course.  I had a discussion once on Talk-Polywell with a GW Johnson, who noted with dismay that he was "one of America's last surviving full-capability ramjet engineers"...
I think that's this fellow.

https://www.youtube.com/watch?v=3MXYY3jnNr0

He's meant to be writing a book on ramjets. One of his blog entries mentions he feels the "dump combustor"  is poorly documented but has potential for more the the use rule-of-thumb range of 3 Mach numbers for a ramjet while remaining within the subsonic combustion regime.

I'd quite like to see his book as it sounds interesting, although I'd really like to see one from Doug Jones, XCOR's (and prior to that Rotary Rockets) key engine man.

AIUI the spill ramjet is more a way of countering thermodynamic losses due to air inlet flow exceeding the flow needed by the core and causing drag. I think Hempsell mentioned they are looking for it to contribute a few 100 m/s only. Again far enough inside the experience envelope (possibly now with GH2) that their design will do what they expect it to.

However this is fairly OT for SABRESkylon as  a whole. 
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Matthew Ak43 on 09/07/2016 10:28 PM
Has anybody heard anything about the USAirforce doing a presentation at  (AIAA) Space conference, in Long Beach, 13-16 September showing plans for Two stage sabre engine vehicles? To be fair to them they said it would be this month or March.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: AnalogMan on 09/07/2016 11:10 PM
Has anybody heard anything about the USAirforce doing a presentation at  (AIAA) Space conference, in Long Beach, 13-16 September showing plans for Two stage sabre engine vehicles? To be fair to them they said it would be this month or March.

Session ST-02 "Resuable Launch Vehicles & Technology" Co-chairs: Adam Dissel  (Reaction Engines, Inc); Barry Hellman (Air Force Research Laboratory)

Tues 13 Sep 2016 4:00-4:30 PM

AIAA-2016-5320. Two Stage to Orbit Conceptual Vehicle Designs using the SABRE Engine B.M. Hellman; J.E. Bradford; B.D. St. Germain; K. Feld
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 09/08/2016 06:36 AM
Has anybody heard anything about the USAirforce doing a presentation at  (AIAA) Space conference, in Long Beach, 13-16 September showing plans for Two stage sabre engine vehicles? To be fair to them they said it would be this month or March.

Session ST-02 "Resuable Launch Vehicles & Technology" Co-chairs: Adam Dissel  (Reaction Engines, Inc); Barry Hellman (Air Force Research Laboratory)

Tues 13 Sep 2016 4:00-4:30 PM

AIAA-2016-5320. Two Stage to Orbit Conceptual Vehicle Designs using the SABRE Engine B.M. Hellman; J.E. Bradford; B.D. St. Germain; K. Feld
Oh dear. Spaceworks Engineering were hired to do consultancy.

So how big will the SCramjet be this time?  :(


The full program is here if nayone is interested.
http://www.aiaa-space.org/uploadedFiles/AIAA-Space_Site/Program/SPACE_2016_FINAL_PRINT_lowRes.pdf
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Asteroza on 09/08/2016 08:39 AM
Has anybody heard anything about the USAirforce doing a presentation at  (AIAA) Space conference, in Long Beach, 13-16 September showing plans for Two stage sabre engine vehicles? To be fair to them they said it would be this month or March.

Session ST-02 "Resuable Launch Vehicles & Technology" Co-chairs: Adam Dissel  (Reaction Engines, Inc); Barry Hellman (Air Force Research Laboratory)

Tues 13 Sep 2016 4:00-4:30 PM

AIAA-2016-5320. Two Stage to Orbit Conceptual Vehicle Designs using the SABRE Engine B.M. Hellman; J.E. Bradford; B.D. St. Germain; K. Feld
Oh dear. Spaceworks Engineering were hired to do consultancy.

So how big will the SCramjet be this time?  :(


The full program is here if nayone is interested.
http://www.aiaa-space.org/uploadedFiles/AIAA-Space_Site/Program/SPACE_2016_FINAL_PRINT_lowRes.pdf

Why the SEI haterade, aside from (generally well justified) generic scramjet dislike? Sure, their concept designs are typically a little big, but there seem to be a fair number of people who have Marquardt ramjets in their blood, which is usually a good thing.

SEI's SCAAT engine on a Skylon body strikes me as a reasonable comparison point to SABRE/Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Star One on 09/08/2016 09:39 AM
Has anybody heard anything about the USAirforce doing a presentation at  (AIAA) Space conference, in Long Beach, 13-16 September showing plans for Two stage sabre engine vehicles? To be fair to them they said it would be this month or March.

Session ST-02 "Resuable Launch Vehicles & Technology" Co-chairs: Adam Dissel  (Reaction Engines, Inc); Barry Hellman (Air Force Research Laboratory)

Tues 13 Sep 2016 4:00-4:30 PM

AIAA-2016-5320. Two Stage to Orbit Conceptual Vehicle Designs using the SABRE Engine B.M. Hellman; J.E. Bradford; B.D. St. Germain; K. Feld
Oh dear. Spaceworks Engineering were hired to do consultancy.

So how big will the SCramjet be this time?  :(


The full program is here if nayone is interested.
http://www.aiaa-space.org/uploadedFiles/AIAA-Space_Site/Program/SPACE_2016_FINAL_PRINT_lowRes.pdf

Why the SEI haterade, aside from (generally well justified) generic scramjet dislike? Sure, their concept designs are typically a little big, but there seem to be a fair number of people who have Marquardt ramjets in their blood, which is usually a good thing.

SEI's SCAAT engine on a Skylon body strikes me as a reasonable comparison point to SABRE/Skylon.

Prepare to receive a lecture on the evil of Scramjets now.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 09/08/2016 02:44 PM
Why the SEI haterade, aside from (generally well justified) generic scramjet dislike? Sure, their concept designs are typically a little big, but there seem to be a fair number of people who have Marquardt ramjets in their blood, which is usually a good thing.

SEI's SCAAT engine on a Skylon body strikes me as a reasonable comparison point to SABRE/Skylon.
I presume that would be this thing.

https://www.sbir.gov/sbirsearch/detail/313205

"The supporting secondary airflow from the inlet and the ramscoops increases the rockets Isp by an average of 15% - 30% when combusted. "

So that's an ISP of about 517-585secs for a LO2/LH2 Isp of 450secs then.

SEI have certainly written a lot of reports about stuff for people but I'm not quite clear what hardware they've built.

Can you point me toward anything they've made, rather than simulated being made in a computer?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Asteroza on 09/09/2016 01:29 AM
Why the SEI haterade, aside from (generally well justified) generic scramjet dislike? Sure, their concept designs are typically a little big, but there seem to be a fair number of people who have Marquardt ramjets in their blood, which is usually a good thing.

SEI's SCAAT engine on a Skylon body strikes me as a reasonable comparison point to SABRE/Skylon.
I presume that would be this thing.

https://www.sbir.gov/sbirsearch/detail/313205

"The supporting secondary airflow from the inlet and the ramscoops increases the rockets Isp by an average of 15% - 30% when combusted. "

So that's an ISP of about 517-585secs for a LO2/LH2 Isp of 450secs then.

SEI have certainly written a lot of reports about stuff for people but I'm not quite clear what hardware they've built.

Can you point me toward anything they've made, rather than simulated being made in a computer?

From the the school of those that can't do, teach...

As far as I am aware, SEI is mostly a paper study consulting outfit that has never built a partial or complete ramjet or scramjet, though they dabble in some hardware, like their GoLauncher air launch system

http://generationorbit.com/ (http://generationorbit.com/)

Currently static flight testing their version 1 rocket (which fits on a learjet wing pylon, did you know that was a purchasable option for a bizjet?!?)

and TVA, an ISS small cargo return capsule venture

http://terminalvelocityaero.com/ (http://terminalvelocityaero.com/)


They are quite literally working the small end of NewSpace activities, though small things are somewhat easier to fund...

Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 09/10/2016 05:56 PM
As far as I am aware, SEI is mostly a paper study consulting outfit that has never built a partial or complete ramjet or scramjet, though they dabble in some hardware, like their GoLauncher air launch system

http://generationorbit.com/ (http://generationorbit.com/)

Currently static flight testing their version 1 rocket (which fits on a learjet wing pylon, did you know that was a purchasable option for a bizjet?!?)
Amazing what you can find in a catalogue, isn't it?  :) I'm curious what they will be using for the engine. going liquid helps with the Isp of course. Logically that's LOX or HTP.
Quote
and TVA, an ISS small cargo return capsule venture

http://terminalvelocityaero.com/ (http://terminalvelocityaero.com/)

They are quite literally working the small end of NewSpace activities, though small things are somewhat easier to fund...
I believe the provision of down mass is substantially under appreciated as an enabling tool for refining components, on orbit mfg systems etc.

I'm curious if these divisions are "home grown" or did SEI buy them up, but that's right OT for this thread.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 09/12/2016 08:32 PM
SEI and SCramjets; Give the customer what they ask for, and occasionally what they actually want rather than what they THINK they want :) SEI does studies for which the customer, (NASA, AF, whoever) tends to set the requirements and assumptions. Size-wise that means you do the work around the amount of payload the customer gives you. Given the amount of money tied up in assuming SCramjets work, when the customer specifies to include them that is what you do. Have to wait till the presentation is available but I'd be surprised if anything REL is involved with includes them.

GW Johnson; Someone needs to sit that man down and record his brain or something. I'm terrified he's going to forget something important, or something and not get stuff written down! :)

GO and TV; SEI helped fund them and has an interest in them. How much control that translates into...

Down-mass is only an issue when you have more of it than you do up-mass which is not really the case currently. Nice to have if you don't put up a lot of mass often though which IS the current case, especially for some proposed automated experimental/production facilities. Nice to see someone thinking about it ahead of the game :)

Plumbing on Learjets; Yep it's an option. It is with any biz-jet that gets sold in a "military" version and can be plumbed before or after it's built. Pretty generic and usually plumbed for multiple uses.

Couple notes, anyone catch the design of the TV capsules? Interesting. The GO-Future stuff is interesting as well.

Back on-topic (ish?): As I understood it the spill-ramjet was something to use left over GH2 is a way to reduce the drag losses, but I was under the impression that there wasn't that much 'waste' GH2 in the system and that the latest version didn't have enough to bother with having a spill-ramjet at all.

Everything I've read on "deep-cooling" versus "liquefying" the air pointed to liquefying needing so much LH2 that you pretty much HAD to come up with ways to either re-liquefy it or specialized propulsion systems to use it because you had to carry far more than you needed. While deep-cooling used so much less LH2 the GH2 'excess' could be used in a spill-ramjet to reduce drag losses, dumped into the existing rocket or ramjet, or just plain dumped and therefore had to carry much less LH2 initially.

The thing is the design and working of such a "spill-ramjet" is tricky, (I recall discussing it with GW Johnson at one point) and it's an open question if the effort is worth it for the performance over a wide operating range. That's part of the reason I understood REL was seeking to reduce the 'waste' GH2 in the first place because your possible 'recovery' is all over the place depending on atmosphere, speed, and AoA.

In something with an adjustable inlet flow like SABRE, especially as you get into speeds over Mach-2/3 where adjustments are constantly happening, it would seem questionable to incorporate unless you have a lot of GH2 to deal with. Adding a few "100k/s" isn't really helpful unless it is consistent enough to effect the average ISP over the whole flight which is doubtful, and again the whole point is that deep-cooling means you have a lot less waste GH2 in the first place. Part of this is because unlike most "combined cycle" engine types the SABRE actually and air-breathing rocket engine so there isn't any convenient place to dump the excess GH2 into the flow path so you can't dump it in the afterburner or duct-burn it as is done in most CC engine designs. So burning it in a bypass, or spill-ramjet to make up some loss during portions of the flight makes sense, especially if you have an intake air imbalance. But on the other hand with a constantly adjusting intake system you shouldn't have that much of an imbalance and it shouldn't be significant enough over the air-breathing flight envelope to justify a specifically designed spill-ramjet.

Nice if you can get it cheap and easy but nothing I've seen says that's the case if you don't have a LOT of GH2 to burn off.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Asteroza on 09/12/2016 11:20 PM
SEI and SCramjets; Give the customer what they ask for, and occasionally what they actually want rather than what they THINK they want :) SEI does studies for which the customer, (NASA, AF, whoever) tends to set the requirements and assumptions. Size-wise that means you do the work around the amount of payload the customer gives you. Given the amount of money tied up in assuming SCramjets work, when the customer specifies to include them that is what you do. Have to wait till the presentation is available but I'd be surprised if anything REL is involved with includes them.

GW Johnson; Someone needs to sit that man down and record his brain or something. I'm terrified he's going to forget something important, or something and not get stuff written down! :)

GO and TV; SEI helped fund them and has an interest in them. How much control that translates into...

Down-mass is only an issue when you have more of it than you do up-mass which is not really the case currently. Nice to have if you don't put up a lot of mass often though which IS the current case, especially for some proposed automated experimental/production facilities. Nice to see someone thinking about it ahead of the game :)

Plumbing on Learjets; Yep it's an option. It is with any biz-jet that gets sold in a "military" version and can be plumbed before or after it's built. Pretty generic and usually plumbed for multiple uses.

Couple notes, anyone catch the design of the TV capsules? Interesting. The GO-Future stuff is interesting as well.

Back on-topic (ish?): As I understood it the spill-ramjet was something to use left over GH2 is a way to reduce the drag losses, but I was under the impression that there wasn't that much 'waste' GH2 in the system and that the latest version didn't have enough to bother with having a spill-ramjet at all.

Everything I've read on "deep-cooling" versus "liquefying" the air pointed to liquefying needing so much LH2 that you pretty much HAD to come up with ways to either re-liquefy it or specialized propulsion systems to use it because you had to carry far more than you needed. While deep-cooling used so much less LH2 the GH2 'excess' could be used in a spill-ramjet to reduce drag losses, dumped into the existing rocket or ramjet, or just plain dumped and therefore had to carry much less LH2 initially.

The thing is the design and working of such a "spill-ramjet" is tricky, (I recall discussing it with GW Johnson at one point) and it's an open question if the effort is worth it for the performance over a wide operating range. That's part of the reason I understood REL was seeking to reduce the 'waste' GH2 in the first place because your possible 'recovery' is all over the place depending on atmosphere, speed, and AoA.

In something with an adjustable inlet flow like SABRE, especially as you get into speeds over Mach-2/3 where adjustments are constantly happening, it would seem questionable to incorporate unless you have a lot of GH2 to deal with. Adding a few "100k/s" isn't really helpful unless it is consistent enough to effect the average ISP over the whole flight which is doubtful, and again the whole point is that deep-cooling means you have a lot less waste GH2 in the first place. Part of this is because unlike most "combined cycle" engine types the SABRE actually and air-breathing rocket engine so there isn't any convenient place to dump the excess GH2 into the flow path so you can't dump it in the afterburner or duct-burn it as is done in most CC engine designs. So burning it in a bypass, or spill-ramjet to make up some loss during portions of the flight makes sense, especially if you have an intake air imbalance. But on the other hand with a constantly adjusting intake system you shouldn't have that much of an imbalance and it shouldn't be significant enough over the air-breathing flight envelope to justify a specifically designed spill-ramjet.

Nice if you can get it cheap and easy but nothing I've seen says that's the case if you don't have a LOT of GH2 to burn off.

Randy

Does that imply that eliminating spill ramjets would lead to running fuel rich out the rocket nozzles then? Is the simplicity worth the direct losses there, compared to either a spill ramjet, or some sort of mixing aerospike nozzle (as E-D nozzle wouldn't provide an usable opportunity to burn external air)
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Archibald on 09/13/2016 11:28 AM


In something with an adjustable inlet flow like SABRE, especially as you get into speeds over Mach-2/3 where adjustments are constantly happening, it would seem questionable to incorporate unless you have a lot of GH2 to deal with. Adding a few "100k/s" isn't really helpful unless it is consistent enough to effect the average ISP over the whole flight which is doubtful, and again the whole point is that deep-cooling means you have a lot less waste GH2 in the first place. Part of this is because unlike most "combined cycle" engine types the SABRE actually and air-breathing rocket engine so there isn't any convenient place to dump the excess GH2 into the flow path so you can't dump it in the afterburner or duct-burn it as is done in most CC engine designs. So burning it in a bypass, or spill-ramjet to make up some loss during portions of the flight makes sense, especially if you have an intake air imbalance. But on the other hand with a constantly adjusting intake system you shouldn't have that much of an imbalance and it shouldn't be significant enough over the air-breathing flight envelope to justify a specifically designed spill-ramjet.

Nice if you can get it cheap and easy but nothing I've seen says that's the case if you don't have a LOT of GH2 to burn off.

Randy

HOTOL actually cooled air by dumping large amounts of liquid hydrogen that then went to waste. Skylon is trying not to bleed liquid hydrogen, hence the helium loop (AFAIK !)
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 09/13/2016 05:01 PM
Does that imply that eliminating spill ramjets would lead to running fuel rich out the rocket nozzles then? Is the simplicity worth the direct losses there, compared to either a spill ramjet, or some sort of mixing aerospike nozzle (as E-D nozzle wouldn't provide an usable opportunity to burn external air)

I thought the engines were already "fuel-rich" which is why I wasn't thinking they could 'dump' into the them :)

HOTOL actually cooled air by dumping large amounts of liquid hydrogen that then went to waste. Skylon is trying not to bleed liquid hydrogen, hence the helium loop (AFAIK !)

The engine design was similar to SABRE as far as anyone can tell so I doubt it dumped "large amounts" so the same issue applied. Looking at various versions of the HOTOL design you'll note that all the way to the last iterations the air intake system was capable of incorporating some type of by-pass or spill burner because the rockets engines weren't directly in the  flow-path as they are with SABRE. This made the HOTOL engine much more complex and heavy but did away with the "dump" issues as you can see in some engine illustrations, and descriptions since it used the some of the 'waste' to power the compressor turbine and some to power a pre-burner. Incorporating a spill-ramjet would have been pretty straight forward especially when they were using the vertical ramp intake system similar to the XB-70 which had a pretty straight forward intake-spill system.
http://www.aerospaceweb.org/question/spacecraft/q0202.shtml
https://en.wikipedia.org/wiki/HOTOL#/media/File:HOTOL.JPG
http://www.astronautix.com/r/rb545.html

And yes that's why SABRE is using the helium loop instead of direct LH2 cooling but again that was pretty much the point in that you had much more GH2 to deal with in the RB545 than in SABRE and improvements continue to reduce the 'waste' but dealing with what there is seems to be a minor issue that continues to crop up.

Which is to be expected of course, issues always crop up :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: 93143 on 09/13/2016 10:17 PM
According to my calculations, SABRE 2/3 as represented in the C1 spreadsheet used roughly 2.7 times as much hydrogen as the core could burn (stoichiometric - if you're airbreathing and have got spill ramjets, I'm not sure running the core fuel-rich does you any good) over the whole airbreathing trajectory.  The ratio varied from about 2.4 to about 2.9 with increasing airspeed.

If one assumes that (a) Skylon D1 goes through exactly the same delta-V before transition as C1, and (b) my calculation of said delta-V (3657 m/s) from the C1 spreadsheet is correct, SABRE 4's average Isp can be calculated from the data in the NISSIG presentation as approximately 4889 s.  The value I got for SABRE 2/3 was 2274 s.  This yields an equivalence ratio for SABRE 4 of about 1.25.

Not bad...  of course that's not constant during the trajectory...
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: FutureSpaceTourist on 09/14/2016 12:21 AM
Session ST-02 "Resuable Launch Vehicles & Technology" Co-chairs: Adam Dissel  (Reaction Engines, Inc); Barry Hellman (Air Force Research Laboratory)

Tues 13 Sep 2016 4:00-4:30 PM

AIAA-2016-5320. Two Stage to Orbit Conceptual Vehicle Designs using the SABRE Engine B.M. Hellman; J.E. Bradford; B.D. St. Germain; K. Feld

Couple of quotes from this talk:

Quote
Jeff Foust ‏@jeff_foust 1h1 hour ago

Barry Hellman, AFRL: SABRE engine technology very fascinating, but it alone doesn’t solve vehicle issues of SSTO Skylon. #AIAASpace
https://twitter.com/jeff_foust/status/775834301082406912 (https://twitter.com/jeff_foust/status/775834301082406912)

Quote
Jeff Foust ‏@jeff_foust 1h1 hour ago

Hellman: instead studied using SABRE on TSTO vehicle concepts, including partially reusable design with 5000 lb payload. #AIAASpace
https://twitter.com/jeff_foust/status/775834522097115138 (https://twitter.com/jeff_foust/status/775834522097115138)
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 09/14/2016 10:33 AM

Couple of quotes from this talk:

Quote
Jeff Foust ‏@jeff_foust 1h1 hour ago
Barry Hellman, AFRL: SABRE engine technology very fascinating, but it alone doesn’t solve vehicle issues of SSTO Skylon. #AIAASpace
https://twitter.com/jeff_foust/status/775834301082406912 (https://twitter.com/jeff_foust/status/775834301082406912)
Was anything going to do that if they decided something cannot be done?

Quote
Quote
Jeff Foust ‏@jeff_foust 1h1 hour ago

Hellman: instead studied using SABRE on TSTO vehicle concepts, including partially reusable design with 5000 lb payload. #AIAASpace
https://twitter.com/jeff_foust/status/775834522097115138 (https://twitter.com/jeff_foust/status/775834522097115138)
Looks like I will finally have to get a twitter account.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 09/14/2016 10:34 AM
If one assumes that (a) Skylon D1 goes through exactly the same delta-V before transition as C1, and (b) my calculation of said delta-V (3657 m/s) from the C1 spreadsheet is correct, SABRE 4's average Isp can be calculated from the data in the NISSIG presentation as approximately 4889 s.  The value I got for SABRE 2/3 was 2274 s.  This yields an equivalence ratio for SABRE 4 of about 1.25.

Not bad...  of course that's not constant during the trajectory...
With those caveats that means you can safely increase the mass growth margins on the designs. Exciting times.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 09/16/2016 09:30 PM
Does anyone have any further information on the SABRE presentation the USAFRL gave last week?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Matthew Ak43 on 09/16/2016 09:32 PM
Conclusion of AFRL paper:
'This paper presented TSTO vehicle designs based on a first stage powered by REL’s SABRE. The first design
presented is a partially reusable vehicle sized for 5,000 lbm to orbit. The second is a scaled up version with an reusable upper stage for 20,000 lbm to orbit. These designs were developed as part of a CRADA between AFRL and REL to understand the scale of TSTO launch systems based on the SABRE. REL's vehicle design effort had originally focused on the Skylon SSTO vehicle concept. The present study sized two TSTO vehicle point designs to evaluate what a potentially lower risk approach to a SABRE-based space access system could be.
These designs have shown that if the SABRE designs performs as predicted, TSTO vehicle options of reasonable
size and scale could be fielded. For the partially reusable stage, the payload fraction is about 1.5% which is typical of vertical launch systems. The PMF of the booster stage is very low compared to traditional launch vehicles but that will allow pleny of flexibility in designing the vehicle. It also is shorter in length then the XB-70 (188ft long) and has a lower takeoff weight as the Concorde (412klbm). The flight loads (dynamic pressure and aeroheating) are in the range of near-term technology. Of course the SABRE is a unqiue cycle that will require significant development to mature. The conformal LH2 tanks used in the nose and aft body sections of the booster are also in need of technology maturation and represent a risk item. This type of tank construction has not been worked significantly since the failed X-33 program. The fully reusable system is still shorter than the Concorde and has a gross weight less on the order of a 747 or A380.
While the options in the paper show potential designs for how the SABRE could be used in a TSTO configuration,
an apples-to-apples comparison to other TSTO concepts is needed. This includes all rocket concepts, turbine based
and rocket based scramjet concepts, and other combined cycle engines. Another interesting trade to consider is using the SABRE cycle with methane or other high endothermic hydrocarbon fuel. For a TSTO system, these fuels could provide a smaller system in physical size and lower empty weight than LH2. These fuels could also simplify ground operations. This however would require some changes to the SABRE thermodynamic cycle that need to be modeled and verified.'
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Matthew Ak43 on 09/16/2016 09:41 PM
Does anyone have any further information on the SABRE presentation the USAFRL gave last week?

Of the two Sabre vehicles that the AFRL proposed. I found the reusable first stage/ expendable upper stage quite interesting. The expendable stage is in a compartment at the front of the vehicle, and is released from the base of the craft. I agree with ARFL that it is a good route to develop this less ambitious craft to start with, which in itself would be a game changer.

Unfortunately, according to Jeff Faust, the AIAA talk was not filmed so we are unlikely to see it on YouTube. There was no indication on what AFRL's plans are, if they are going to proceed with either vehicle. I guess they are sensibly waiting for the engine prototype, which REL and BAE say will be around 2020.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: t43562 on 09/17/2016 08:09 AM
(https://scontent-frt3-1.xx.fbcdn.net/v/t1.0-9/14368653_336995833302024_947965907128815714_n.jpg?oh=1cbdbedc1730b83fe2a4aa2da5151657&oe=58806A70)
(Thanks Matthew!)
Title: The Reaction Engines Skylon Master Thread (6)
Post by: Star One on 09/17/2016 08:24 AM
Is there any particular reason that design has more than passing resemblance to the SR-71.

By the way can this paper be found online anywhere?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Matthew Ak43 on 09/17/2016 10:32 AM
On the AIAA website. But you have to pay $25, for a 15 page PDF.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Star One on 09/17/2016 12:03 PM
On the AIAA website. But you have to pay $25, for a 15 page PDF.

Thank you. Be interesting to see if it will accept out of US payment.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 09/17/2016 12:27 PM
Does anyone have any further information on the SABRE presentation the USAFRL gave last week?

Of the two Sabre vehicles that the AFRL proposed. I found the reusable first stage/ expendable upper stage quite interesting. The expendable stage is in a compartment at the front of the vehicle, and is released from the base of the craft. I agree with ARFL that it is a good route to develop this less ambitious craft to start with, which in itself would be a game changer.

Unfortunately, according to Jeff Faust, the AIAA talk was not filmed so we are unlikely to see it on YouTube. There was no indication on what AFRL's plans are, if they are going to proceed with either vehicle. I guess they are sensibly waiting for the engine prototype, which REL and BAE say will be around 2020.
Thanks for the conclusions and welcome to the forum.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 09/17/2016 01:03 PM
I've attached a small spread sheet breaking down the figures in t43562's graphic in terms of dry and gross takeoff weights as percentages.

There are a few discrepancies.  I calculated the Gross Dry Weight by summing the previous items. It comes up 10lbs short compared to the number on the graphic. Logically the sum should be the sum of the parts on this item. This looks like an error.

Likewise I derived GTOW from Weight at Staging plus the following 4 items. That came up 1380lb short to the stated figure. I'm guessing this is the propellant used between staging and RTLS. Presumably some part of this flight will be powered?

I'll leave others to comment if they think the figures they've given for other parts of the design seem sensible. I'm quite sure a payload of 1.58% is well below that of TSTO ELV's. They've also got a landing gear mass of 4% of GTOW for a start. I'll also note they've got an expendable LH2 upper stage. Given all the concern for "risk" this seems rather odd. People might like to check the figure for main propulsion versus GTOW.

I'd very much like to know what they plan for a TPS.

BTW the conclusions part of their paper talks about an "apples to apples" comparison. I'd like to see that with actual TRL's of those other systems they plan to judge against and wheather the actual hardware is off the shelf (IE existing engine design already built), being developed or just we-could-do-this-if-you-paid-us.



Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Archibald on 09/17/2016 04:16 PM
TSTO with expendable upper stage ?  with a 5000 pounds payload ? Reminds me of the XS-1, which doesn't need sabre engines in any way. I vastly prefer the Skylon SSTO by itself.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: t43562 on 09/19/2016 01:31 PM
(https://scontent-frt3-1.xx.fbcdn.net/v/t1.0-9/14292425_337358886599052_6592270771529262582_n.jpg?oh=57696af087644f9a6d44388f39e0a87d&oe=5874533D)
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Ravenger on 09/19/2016 04:05 PM
The whole point of Skylon was to learn from the mistakes of HOTOL, where the engines at the rear caused a huge pitching moment as the fuel supply was used up and the COG shifted. The measures used to correct this cut into the payload fraction so much that HOTOL became an 'expensive method of sending hydraulics into orbit'.

Surely the above SR71 style concept with the engines towards the rear of the fuselage could suffer from the same issue? Or is it not as big a problem as the booster is only sub-orbital?

It looks remarkably like the SR71/D21 drone system developed by the Skunk Works. In the end there were too many problems launching the drone at Mach 3 from the carrier aircraft (including the tragic loss of a SR71 and crew) so they resorted to launching off a B52 with a solid rocket booster to get it up to speed.

To be honest I can't easily see how this two stage concept would be more reliable or easier to achieve than a Skylon SSTO, especially as hypersonic staging is so risky.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 09/19/2016 05:29 PM
The whole point of Skylon was to learn from the mistakes of HOTOL, where the engines at the rear caused a huge pitching moment as the fuel supply was used up and the COG shifted. The measures used to correct this cut into the payload fraction so much that HOTOL became an 'expensive method of sending hydraulics into orbit'.

Surely the above SR71 style concept with the engines towards the rear of the fuselage could suffer from the same issue? Or is it not as big a problem as the booster is only sub-orbital?

"Shifts-happen"? :) Seriously the SR-71 had similar shifts in transonic performance as well and the engines are actually located at what would be the COG/COP shift point. The larger wing area helps dampen out the shifts as well.

Additionally the engines here are placed to take some advantage of the body-nose compression from shockwaves unlike the Skylon which has the engines mounted so as to avoid any interaction with the body's slipstream.

Quote
It looks remarkably like the SR71/D21 drone system developed by the Skunk Works. In the end there were too many problems launching the drone at Mach 3 from the carrier aircraft (including the tragic loss of a SR71 and crew) so they resorted to launching off a B52 with a solid rocket booster to get it up to speed.

Not there are two different launch methods with the expendable being dropped from in internal bay while the reusable is supposedly mounted on the back. There were few problems launching the D21 from the M21 (SR71 derived) other than the one failure of a D21 autopilot which dove the D21 back down into the M21 a few seconds after release from the M21. Continued un-reliability of the D21 autopilot system precluded the higher risk launches using the M21 as well as the cost of the M21 and flight operations over the "simpler" and "safer" rocket powered launch. Later studies by both the Air Force and NASA again suggested using the SR-71 as a launch platform and determined that the back of a super/hypersonic-platform had a very stable and benign environment for launch compared to any other placement as the launched vehicle would remain behind and inside the carrier vehicle shock-cone and allowing it to attain stable flight with little outside influencing factors.

Of course really none of that matters as the proposed concept doesn't stage in the effective atmosphere.

Quote
To be honest I can't easily see how this two stage concept would be more reliable or easier to achieve than a Skylon SSTO, especially as hypersonic staging is so risky.

Hypersonic staging is only risky if you do it too deep in the atmosphere. Since the staging takes place around Mach-8 and 265,000ft/50miles/80km the drag and interactions are going to be minimal.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: lkm on 09/19/2016 05:55 PM
So I'm confused. Either l'm reading this stuff wrong or not much of this makes sense.
If the reusable first stage is 57m long then we should be able to guesstimate the tank volume from the design, and when I do that I make it over 1000m3 or over three the volume required by the reusable first stage mission. In fact it likely has enough tankage to put the entire 16mt second stage in orbit by itself ( it's actually short on oxygen and long on hydrogen tankage). The entire payload section seems mass inefficient when that tankage could more efficiently be added to the fore and aft tanks. The need to include a very long payload bay seems to have created a very unoptimisable design.
Perhaps the tankage is scaled so because that's the tank volume required by the fully reusable mission but that vehicle has a higher dry weight.
 Or perhaps the USAF has a need for a very long narrow downward dropping payload bay on a Mach 8 capable vehicle with a range requirement which has driven the tankage volume and has called this vehicle a reusable booster to spare our blushes.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 09/19/2016 09:17 PM
I'll note a few points about that fully reusable 20Klb system

Excluding the 20Klb payload from the upper stage gross mass gives a dry weight that's 17% of propellant. considerably lower than Skylon, which remember is considered too risky as a concept, partly because it's structural mass is so low. Including the payload puts the structural fraction about 15%. So how are they going to build this structure ?

Kelly Johnson considered the M21/D21 drone project too dangerous to continue with but IIRC part of that was due to the (relatively) narrow clearance between the drone and inward canted twin tails on the SR71. Obviously without needing stealth that would not be a problem for the design and of course modern autopilots are much better at this stuff than they were. Staging at an altitude where atmospheric pressure is measured in pounds per foot also reduces issues but logically implies you'll be needing an RCS since control surfaces won't be very effective.

If you're going for full reusability then you'll need full orbital TPS and I'm still not clear what they have in mind for this.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: momerathe on 09/21/2016 07:05 AM
can anyone see behind this paywall?
http://aviationweek.com/new-space/reaction-engines-refines-hypersonic-engine-demonstrator-plan
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: francesco nicoli on 09/21/2016 11:39 AM
can anyone see behind this paywall?
http://aviationweek.com/new-space/reaction-engines-refines-hypersonic-engine-demonstrator-plan

nope... but if anyone does, please recall the main points OR the original source, so we can identify it!

best,

Francesco
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Star One on 09/21/2016 04:09 PM
can anyone see behind this paywall?
http://aviationweek.com/new-space/reaction-engines-refines-hypersonic-engine-demonstrator-plan

Try this link instead.

http://www.nextbigfuture.com/2016/09/fighter-engine-size-hypersonic-ground.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed:+blogspot/advancednano+(nextbigfuture)&utm_content=FaceBook&m=1
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Paul451 on 09/21/2016 11:13 PM
can anyone see behind this paywall?
http://aviationweek.com/new-space/reaction-engines-refines-hypersonic-engine-demonstrator-plan
Try this link instead.
http://www.nextbigfuture.com/2016/09/fighter-engine-size-hypersonic-ground.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed:+blogspot/advancednano+(nextbigfuture)&utm_content=FaceBook&m=1

The NBF article includes nothing about the single-engine demonstrator, it just regurgitates general decade old info about Skylon/SABRE.

[Edit: The key phrase in the pre-Paywalled summary would be "fighter engine-size ground demonstrator" I suspect. In other words, nothing to see here, we already knew they'd do this. The only new info would be an estimated date.]
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Star One on 09/21/2016 11:25 PM
can anyone see behind this paywall?
http://aviationweek.com/new-space/reaction-engines-refines-hypersonic-engine-demonstrator-plan
Try this link instead.
http://www.nextbigfuture.com/2016/09/fighter-engine-size-hypersonic-ground.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed:+blogspot/advancednano+(nextbigfuture)&utm_content=FaceBook&m=1

The NBF article includes nothing about the single-engine demonstrator, it just regurgitates general decade old info about Skylon/SABRE.

[Edit: The key phrase in the pre-Paywalled summary would be "fighter engine-size ground demonstrator" I suspect. In other words, nothing to see here, we already knew they'd do this. The only new info would be an estimated date.]
Though I have an AW login it doesn't unfortunately let me into that article as it's marked as premium content.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: momerathe on 09/22/2016 11:46 AM
[Edit: The key phrase in the pre-Paywalled summary would be "fighter engine-size ground demonstrator" I suspect. In other words, nothing to see here, we already knew they'd do this. The only new info would be an estimated date.]

What pinged my radar was "fighter engine-size". Firstly because of previous comments on the difficulty of scaling the engine down, and secondly because of my ongoing suspicion that BAE are more interested in a hypersonic bomber than an SSTO.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Star One on 09/22/2016 11:54 AM
[Edit: The key phrase in the pre-Paywalled summary would be "fighter engine-size ground demonstrator" I suspect. In other words, nothing to see here, we already knew they'd do this. The only new info would be an estimated date.]

What pinged my radar was "fighter engine-size". Firstly because of previous comments on the difficulty of scaling the engine down, and secondly because of my ongoing suspicion that BAE are more interested in a hypersonic bomber than an SSTO.

I imagine they are interested in providing the engines for something like LM's proposed SR-72 hypersonic global strike/ISR aircraft.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: 93143 on 09/22/2016 06:01 PM
previous comments on the difficulty of scaling the engine down

It's not that it couldn't be scaled down at all - just that scaling it down a lot results in a very expensive ultra-high-speed hydrogen turbopump, limiting the cost benefits of going small.  And even that might be subject to finesse if they're after a fighter engine rather than an accurate subscale simulation of a Skylon engine, particularly if they're using the SABRE 4 cycle...
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: lkm on 09/22/2016 09:29 PM
[Edit: The key phrase in the pre-Paywalled summary would be "fighter engine-size ground demonstrator" I suspect. In other words, nothing to see here, we already knew they'd do this. The only new info would be an estimated date.]

What pinged my radar was "fighter engine-size". Firstly because of previous comments on the difficulty of scaling the engine down, and secondly because of my ongoing suspicion that BAE are more interested in a hypersonic bomber than an SSTO.
If you're  only interested in testing the cycle and not actually using the engine in anything then it's actually pretty simple to scale down a SABRE engine, just cut it in half. The engine (SABRE 3 at least)  is designed such that there's 2 of everything past the compressor for safety reasons, so to scale the engine you can easily build it at half scale with only a single set of full sized components attached to a smaller compressor and precooler. But it will lack all the redundancy and safety benefits of a full size engine and be fundamentally less safe.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Matthew Ak43 on 09/22/2016 09:36 PM
Here's the AFRL paper in full.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Katana on 09/23/2016 02:54 AM
[Edit: The key phrase in the pre-Paywalled summary would be "fighter engine-size ground demonstrator" I suspect. In other words, nothing to see here, we already knew they'd do this. The only new info would be an estimated date.]

What pinged my radar was "fighter engine-size". Firstly because of previous comments on the difficulty of scaling the engine down, and secondly because of my ongoing suspicion that BAE are more interested in a hypersonic bomber than an SSTO.

I imagine they are interested in providing the engines for something like LM's proposed SR-72 hypersonic global strike/ISR aircraft.

SR71's proposed suntan project, precursor of RL-10...
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Katana on 09/23/2016 03:24 AM
Is it possible to have a polite discussion about how SpaceX and Blue Origin affect Reaction Engines without it going off-course into a shouting match about whether SpaceX can't or didn't choose to build a reusable second stage?  I hope so, because I think it's an important issue for Reaction Engines.

The original value proposition of Skylon was versus the old state-of-the-art: expensive, expendable launch vehicles.  Now, the state of the art is changing.  As both Blue Origin and SpaceX move closer to inexpensive, reusable launch vehicles, it erodes the value proposition of Skylon in comparison.  It's one thing to say they want to spend $16 billion to produce a system that reduces launch costs from $250 million per launch to $5 million per launch.  It's a harder sell if the reduction is from $60 million to $5 million.  And even harder when the reduction is from $40 million, then $20 million, and so on.

On the other hand, having other competitors moving toward a low-cost launch system could prove and expand the market, giving investors confidence to invest in REL, particularly if Europe is afraid of the new low-cost launchers and wants its own alternative.

So, which is the bigger effect?  My opinion is that the changes in the market from Blue Origin and SpaceX will have much more of a negative effect on REL than a positive effect.
Not so bad.

Investors in EU could be stimulated by SpaceX /BO and willing to invest on some alternative, regardless of actural technical details (reusable second stage, etc). Somewhat similliar to Rlabs, Firefly, Vector, etc.

Technically, SABRE engines may power some VTVL first stage either. But this is Not the right story to tell now.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 09/23/2016 01:47 PM
Here's the AFRL paper in full.
Thanks. That will give a lot of food for thought.

SR71's proposed suntan project, precursor of RL-10...
No. The Martin "Suntan" was the official winner of the competition. Lockheed (they were 2 separate companies) lobbied hard and eventually the A12 design got accepted.

Suntan provided the Hydrogen turbo pump for what became the RL10.
If you're  only interested in testing the cycle and not actually using the engine in anything then it's actually pretty simple to scale down a SABRE engine, just cut it in half. The engine (SABRE 3 at least)  is designed such that there's 2 of everything past the compressor for safety reasons, so to scale the engine you can easily build it at half scale with only a single set of full sized components attached to a smaller compressor and precooler. But it will lack all the redundancy and safety benefits of a full size engine and be fundamentally less safe.
That gives you an engine that's got the thrust of just 2 1/4 Trent 900's (one engine option for the A380).

The problem is the Hydrogen turbo pump and especially the chamber pressure

Pump designers talk in terms of the static head. How high would a column of the fluid need to be to exert the same pressure as the pump at the base. LH2 columns are measured in kilometres. REL's view has always been why speed a disproportionate amount of money for what is essentially a 1 shot engine.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Archibald on 09/23/2016 02:28 PM
Here's the AFRL paper in full.


thank you for the paper, an interesting read, but I'm still not convinced at all.
- The 5000 Ibs payload / expendable stage brings nothing when compared to the all rocket DARPA XS-1.
- As for the 20 000 pounds payload AND reusable upper stage - well, SpaceX in 2011 showeved a reusable stage 2 but since then it has been buried indefinitively. Whatever way is used to recover stage 2 there is a serious weight penalty that eat the payload (even worse when the stage is made winged)

By the way, the document CGI was rather crappy. It looked like CGI from the late 90's.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 09/23/2016 03:09 PM
I've just had a first look at the report. I'll be updating my spread sheet with the data from the upper stage options.

As always the devil is in the details. In this case the assumptions you start the various pieces of software running with.

"Engines were sized for a takeoff T/W of 0.7" Why ?

Historically engine thrust has been about 1/3 GTOW for HTOL vehicles.  Concorde (with reheat at takeoff) was about 0.37 and the Firebee drones did supersonic cruise with T/W at 0.5. That makes a huge difference in engine weight. Given the opacity of the "Mass Estimating Relationships" used (Might have been the USAF program, might not) it's unclear what knock on effects this would have had. I'd guess they would be substantial. 

So why assume a HTOL booster needs so much more T/W?

As for the propellant mass fraction being lower than a rocket well it's not a rocket, it's an aircraft. So how does that compare with big aircraft? In fact why is it important?

Incidentally I did not know that "pleny" is actually a word.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Jim Davis on 09/23/2016 11:31 PM
No. The Martin "Suntan" was the official winner of the competition. Lockheed (they were 2 separate companies) lobbied hard and eventually the A12 design got accepted.

No, Suntan (the Lockheed CL-400 design) was a Lockheed design. Kelly Johnson quickly realized that LH2 was not ready for prime time and offered to design a "conventional" design in its place. This design eventually became the A-12.

You may be thinking about another, earlier, competition that Lockheed managed to wrest away from its nominal winner. Bell won the competition for a high altitude reconnaissance aircraft with a twin engine design which was designated the X-16. Lockheed, represented by Kelly Johnson, kept pushing for its own design which was a single engine design that looked like an F-104 with high aspect ratio wings. This design eventually prevailed and became the U-2.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 09/24/2016 09:55 AM
No. The Martin "Suntan" was the official winner of the competition. Lockheed (they were 2 separate companies) lobbied hard and eventually the A12 design got accepted.

No, Suntan (the Lockheed CL-400 design) was a Lockheed design. Kelly Johnson quickly realized that LH2 was not ready for prime time and offered to design a "conventional" design in its place. This design eventually became the A-12.

You may be thinking about another, earlier, competition that Lockheed managed to wrest away from its nominal winner. Bell won the competition for a high altitude reconnaissance aircraft with a twin engine design which was designated the X-16. Lockheed, represented by Kelly Johnson, kept pushing for its own design which was a single engine design that looked like an F-104 with high aspect ratio wings. This design eventually prevailed and became the U-2.
I think I've comflated Lockheed's behavior in the first with that of the second.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 09/26/2016 01:28 AM
I've now had a chance to read the report and added the numbers for the upper stage and fully reusable versions to my spreadsheet on additional worksheets. As before I've related the raw numbers to percentages of GTOW or gross weight of stage and of dry weight of stage. My original reservation about why they made the T/O Thrust to Weight so high and mentioned the propellant mass fraction was low compared to a VTO ELV remain.

As before I calculated values for numbers which should have been derived by summing items higher up the charts as a sanity check . The results are somewhat worrying.

For the expendable option the Dry Weight is 88lbs lighter than the number given, as is the inert weight. Using the listed numbers for inert weight added to propellant masses, payload and payload adapter gives a number that's 630lb too small.

BTW the Mass Growth Allowance is 650 lb yet this seems to be factored in to Dry Weight and is 20lbs too big to account for the discrepancy.

This suggests a) there is an 650lb item left off the BoM for some reason. b) someone cannot seem to add up, or c) can't get a spreadsheet to add it up for them.  :(

The 20 000lb "fully reusable " is very low resolution. There is no mass break down and it's RP1, despite authors saying it would probably use LH2 as well. The GTOW given is bigger than the sum of the stage gross weights by over a 1/4 of a million lbs. ???

Incidentally using the Upper Stage Gross and dry weights shows a design with a structure that is under 16% of fully fueled mass (it's just under 3.8% of the GTOW if you use the reports figure of 1 300 000lbs). Skylon is 16% without consumables and reserves, about 18% with (giving what the expendable stage figures calls the "inert" weight).

Perhaps these weights are not meant to be calculable by adding up previous items. Perhaps there has been a "reserve pile up" as levels of "growth allowance" have been applied one atop the other. Perhaps an intern mis-keyed some numbers on their calculator (but if so why were they using a calculator to begin with?)

Maybe the graphs are more accurate because they were produced by programs in their development framework. I'm still not clear why a 5g turn is needed in the flight path, nor why the booster doesn't run in airbreathing up to the full M5.5. Because the computer says it's not optimal,  apparently. :(

Some of the conclusions are quite baffling. "SABRE is a unqiue cycle that will require significant development to mature." Left out is the fact most of that can be achieved in a ground facility without building a full size flight vehicle.

"conformal LH2 tanks used in the nose and aft body sections of the booster are also in need of technology maturation and represent a risk item." Then why were they chosen? The report does not say.  :(   It implies they would be composite but one of the often forgotten facts of the X33 programme was that an Aluminum conformal tank was made that was the same mass as the problematical composite tank. However a former Boeing engineer (I'm not sure who he was working for) testified before Congress this would eliminate the audit trail between the X-33 and the supposed commercial "Venturestar" LV.  NASA and LM accepted this with results that are now history.  :(

As for another trade study between SABRE, Rocket, RBCC, TBCC and SCRamjet well consultancy firms always want another trade study. Either you want to do this or you don't and you want to do it because SABRE gives you unique advantages over other engines and you already know this, otherwise you wouldn't have chosen it in the first place, would you?

With the switch to the SABRE 4 cycle and its (presumed) lower chamber pressures using Methane might now be in the range of possible changes.

I think this study has reassured people that if SABRE meets it's performance objectives then a system could be built round it that did not have to be SSTO to work. 

And they managed to avoid adding a SCramjet to the design as well.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Asteroza on 09/26/2016 07:40 AM
5G turn was to simplify return to runway, as it would be a straight shot in to CCAFS shuttle runway. I guess somebody really did not want to do low speed turns to do a runway alignment like the old shuttle HAC.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: t43562 on 09/26/2016 10:30 AM
This is available now:

http://m.aviationweek.com/technology/reaction-engines-refines-hypersonic-engine-demonstrator-plan
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 09/26/2016 04:14 PM
This is available now:

http://m.aviationweek.com/technology/reaction-engines-refines-hypersonic-engine-demonstrator-plan
Funny I could have sworn something like this was listed a week or two ago under "premium content."

Just to give some scale a full size SABRE thrust is about 4 1/4x that of a Trent 900, the usual engine on an Airbus 380. Roughly 80 000lb thrust.  "Fighter size" is more like 10-20 000lb thrust or RL10 size, which is an appropriate metric here.  Using the USAFRL model of T/W of 0.7 that would be a flight vehicle of about 57 000lb, but that would be the TSTO with the ELV. Not going to do anywhere near 5 000lb to orbit. 
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: t43562 on 09/26/2016 05:25 PM
They say 44,000lb thrust for the fighter-sized engine which is about the same as an F-136 (and F-135, sorry)  with afterburner - at least according to wikipedia. 
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: CameronD on 09/27/2016 01:19 AM
This is available now:

http://m.aviationweek.com/technology/reaction-engines-refines-hypersonic-engine-demonstrator-plan
Funny I could have sworn something like this was listed a week or two ago under "premium content."

Just to give some scale a full size SABRE thrust is about 4 1/4x that of a Trent 900, the usual engine on an Airbus 380. Roughly 80 000lb thrust.  "Fighter size" is more like 10-20 000lb thrust or RL10 size, which is an appropriate metric here.  Using the USAFRL model of T/W of 0.7 that would be a flight vehicle of about 57 000lb, but that would be the TSTO with the ELV. Not going to do anywhere near 5 000lb to orbit.

I read that article as meaning they were planning to build a ground demonstrator the same physical size as a fighter engine.  It would not necessarily be the same thrust, but perhaps if it was (or better!) they could break into another market.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 09/27/2016 01:21 AM
A few years back I mentioned that they should test a "scaled down" engine as was done with with NASA/Lockheed Martin Linear Aerospike SR-71 Experiment (LASRE) and was told that it was not needed. I'm glad the Air Force agrees with me. ;) Hopefully it will lead to an inflight test as well... 8)
http://www.nasa.gov/centers/dryden/history/pastprojects/SR71/Lasre/index.html
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 09/27/2016 02:00 PM
A few years back I mentioned that they should test a "scaled down" engine as was done with with NASA/Lockheed Martin Linear Aerospike SR-71 Experiment (LASRE) and was told that it was not needed. I'm glad the Air Force agrees with me. ;) Hopefully it will lead to an inflight test as well... 8)
http://www.nasa.gov/centers/dryden/history/pastprojects/SR71/Lasre/index.html
There is no indication that the USAF is with you. They are talking about the first stage of a 2 stage launch system, not a prototype test of anything.

NASA were never able to get LASRE to ignite in flight.  It was another part of the X33 programme they could not get to work.

I think we all want an inflight test.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: adrianwyard on 09/27/2016 04:11 PM
http://m.aviationweek.com/technology/reaction-engines-refines-hypersonic-engine-demonstrator-plan

There’s a lot of interesting new info in this article, and as many points are supported by Mark Thomas quotes, it's authoritative. To summarize it would probably require a post that’s just as long but here are a few highlights:

+ REL are no longer working on a full size SABRE test engine - this F135-sized demonstrator is it. 44Klb of thrust.
+ They considered an even smaller demonstrator, but decided this is the sweet-spot - the sort of thing that could fit in an F35 or X-plane.
+ The graphical depiction of this small engine has precooler, plumbing, and a single nozzle, i.e no bypass burner, but this may be artistic license as the bypass is mentioned in the description of test plans.
+ They are embracing the concept of modularity rather than scaling. So if an application needs more thrust, add more engines.
+ Construction and some testing will be done in the UK, but quoting Thomas on ITAR: “Designing and making an article here in the UK for testing may result in that article remaining in the U.S., and we are fine with that. If that gets the job done and puts results in the hands of decision-makers, that is a price we would be willing to pay.” 
+ There is mention of the methanol/anti-icing technology which IIRC means it will be closer to SABRE 3 than SABRE 4.

This is all very exciting indeed for REL and the technology itself, but something else is implicit: Skylon/SSTO is no longer the focus for Reaction Engines. in fact judging from this article alone, I’d guess that Skylon is effectively dead, or at least won't be looked at again until the early 2020s. And those commenters who predicted military applications of SABRE would come to the foreground have been proven right.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Star One on 09/27/2016 05:07 PM
http://m.aviationweek.com/technology/reaction-engines-refines-hypersonic-engine-demonstrator-plan

There’s a lot of interesting new info in this article, and as many points are supported by Mark Thomas quotes, it's authoritative. To summarize it would probably require a post that’s just as long but here are a few highlights:

+ REL are no longer working on a full size SABRE test engine - this F135-sized demonstrator is it. 44Klb of thrust.
+ They considered an even smaller demonstrator, but decided this is the sweet-spot - the sort of thing that could fit in an F35 or X-plane.
+ The graphical depiction of this small engine has precooler, plumbing, and a single nozzle, i.e no bypass burner, but this may be artistic license as the bypass is mentioned in the description of test plans.
+ They are embracing the concept of modularity rather than scaling. So if an application needs more thrust, add more engines.
+ Construction and some testing will be done in the UK, but quoting Thomas on ITAR: “Designing and making an article here in the UK for testing may result in that article remaining in the U.S., and we are fine with that. If that gets the job done and puts results in the hands of decision-makers, that is a price we would be willing to pay.”
+ There is mention of the methanol/anti-icing technology which IIRC means it will be closer to SABRE 3 than SABRE 4.

This is all very exciting indeed for REL and the technology itself, but something else is implicit: Skylon/SSTO is no longer the focus for Reaction Engines. in fact judging from this article alone, I’d guess that Skylon is effectively dead, or at least won't be looked at again until the early 2020s. And those commenters who predicted military applications of SABRE would come to the foreground have been proven right.

As to your last point in my mind this was utterly inevitable as soon as BAE took a stake in REL. It's been clear for a little while that they have little to no interest in Skylon at this time or the near future, their eyes have been firmly set on the USAF.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: CrewtaiL on 09/27/2016 09:33 PM
+ Construction and some testing will be done in the UK, but quoting Thomas on ITAR: “Designing and making an article here in the UK for testing may result in that article remaining in the U.S., and we are fine with that. If that gets the job done and puts results in the hands of decision-makers, that is a price we would be willing to pay.”

Could you expand a little on what this means, please. Not sure I've grasped the implications (of ITAR) vis-a-vis technology transfer in a situation as described above by Thomas.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 09/27/2016 09:42 PM
A few years back I mentioned that they should test a "scaled down" engine as was done with with NASA/Lockheed Martin Linear Aerospike SR-71 Experiment (LASRE) and was told that it was not needed. I'm glad the Air Force agrees with me. ;) Hopefully it will lead to an inflight test as well... 8)
http://www.nasa.gov/centers/dryden/history/pastprojects/SR71/Lasre/index.html
There is no indication that the USAF is with you. They are talking about the first stage of a 2 stage launch system, not a prototype test of anything.

NASA were never able to get LASRE to ignite in flight.  It was another part of the X33 programme they could not get to work.

I think we all want an inflight test.
All I'm speaking about John is a "scaled down" engine "size wise" as was LASRE... nothing more... Engine worked good on the ground. :)  I'm looking forward to the scaled ground test as the engine fascinates me technically... I still hope the USAF is with me though in protecting it's citizens... ;D
https://www.youtube.com/watch?v=FcW9kUUTfxY
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 09/27/2016 10:01 PM
As to your last point in my mind this was utterly inevitable as soon as BAE took a stake in REL. It's been clear for a little while that they have little to no interest in Skylon at this time or the near future, their eyes have been firmly set on the USAF.
While anything that gets to a flight demonstration is better than nothing this will do little, if anything to lower the cost of launch to orbit, which was a key part of the Skylon business model. The recurring cost will converge on the refurb cost + upper stage new build cost of the US, just like any other design based on this architecture.  :(
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: adrianwyard on 09/27/2016 10:36 PM
+ Construction and some testing will be done in the UK, but quoting Thomas on ITAR: “Designing and making an article here in the UK for testing may result in that article remaining in the U.S., and we are fine with that. If that gets the job done and puts results in the hands of decision-makers, that is a price we would be willing to pay.”

Could you expand a little on what this means, please. Not sure I've grasped the implications (of ITAR).

ITAR is Internation Traffic in Arms Regulations
https://en.wikipedia.org/wiki/International_Traffic_in_Arms_Regulations

It's complicated, so others may chime in, but in essence: since SABRE has clear military/missile applications, ITAR means once the US is involved 'exports' are prohibited, even to the UK, and even if it originated there.

EDIT:
It's not clear to me what would happen to test data gathered in the US. Would that be restricted to REL's US subsidiary?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: CrewtaiL on 09/27/2016 11:29 PM
ITAR is Internation Traffic in Arms Regulations
https://en.wikipedia.org/wiki/International_Traffic_in_Arms_Regulations

It's complicated, so others may chime in, but in essence: since SABRE has clear military/missile applications, ITAR means once the US is involved 'exports' are prohibited, even to the UK, and even if it originated there.

EDIT:
It's not clear to me what would happen to test data gathered in the US. Would that be restricted to REL's US subsidiary?
[/quote]

Thanks for your reply.

I still don't understand the statement made by Mr Thomas. He says that an article designed and made in the UK may result in permanent relocation to the US and that that's a price worth paying. What exactly is he referring to by the word 'price' and why would it be worth paying? And what would this mean for transfer of proprietary knowledge?

I realise these are pretty basic, if not outright stupid, questions but it's driving me nuts trying to parse his words sans a proper grasp of ITAR/the industry.

Also, as this is only my second post, I'd just like to thank everybody for their contribution to this forum and thread - been a reader for a while.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 09/27/2016 11:31 PM
It's complicated, so others may chime in, but in essence: since SABRE has clear military/missile applications, ITAR means once the US is involved 'exports' are prohibited, even to the UK, and even if it originated there.
Indeed. The classic case was in the early 90's when the former USSR shipped over a couple of (inert) space reactors and the US would not "export" IE return them to the country that sent them in the first place.
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EDIT:
It's not clear to me what would happen to test data gathered in the US. Would that be restricted to REL's US subsidiary?
That's likely to be tricky too. There's nothing like ITAR to make any foreign national in such a meeting feel like they have suddenly become North Korean.  :(
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: adrianwyard on 09/28/2016 12:20 AM
ITAR is Internation Traffic in Arms Regulations
https://en.wikipedia.org/wiki/International_Traffic_in_Arms_Regulations

It's complicated, so others may chime in, but in essence: since SABRE has clear military/missile applications, ITAR means once the US is involved 'exports' are prohibited, even to the UK, and even if it originated there.

EDIT:
It's not clear to me what would happen to test data gathered in the US. Would that be restricted to REL's US subsidiary?
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Thanks for your reply.

I still don't understand the statement made by Mr Thomas. He says that an article designed and made in the UK may result in permanent relocation to the US and that that's a price worth paying. What exactly is he referring to by the word 'price' and why would it be worth paying? And what would this mean for transfer of proprietary knowledge?

I realise these are pretty basic, if not outright stupid, questions but it's driving me nuts trying to parse his words sans a proper grasp of ITAR/the industry.

Also, as this is only my second post, I'd just like to thank everybody for their contribution to this forum and thread - been a reader for a while.

I think he's just saying if testing had to be done in the US to convince the USAF to continue involvement and/or funding, then the 'price' of dealing with ITAR restrictions would be worth it. The price would not be in terms of cash but rather the hassle - and perhaps REL Ltd not even being able to see the results of tests performed on REL supplied hardware.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Asteroza on 09/28/2016 01:06 AM
ITAR is all about dual-use technology "contamination" from a US export perspective, irrespective of origin.

It's why a NASA presentation on martian balloons had to be censored. It's why there are mercs sometimes guarding cubesat payloads outside the US.

 It's also why there is an entire space hardware industry around ITAR-free tagged hardware, because once a part becomes contaminated, the entire vehicle comes under ITAR administration. And contamination includes transfer of technical information.

Which means a test article sent to the US effectively can not return, and there is the distinct possibility that the test result data itself will be governed under ITAR, meaning it will be unavailable to REL UK (at least without backtainting REL UK work). It really is gambling with the devil.

There is a distinct economic interest in SABRE not becoming ITAR tainted, on a european and a general/global basis.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: adrianwyard on 09/28/2016 01:39 AM
The window for substantial European investment has been open for decades, so can we really blame REL for taking the USAF/ITAR gamble?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 09/28/2016 02:17 AM
The window for substantial European investment has been open for decades, so can we really blame REL for taking the USAF/ITAR gamble?
And REL have resisted choosing it for decades, until BAE became an investor.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Turbomotive on 09/28/2016 07:08 AM
The window for substantial European investment has been open for decades, so can we really blame REL for taking the USAF/ITAR gamble?

Agree - ESA could have conceivably been more enthusiastic about Skylon as the next-gen launch system. Instead, CNES ensured it would be Ariane 6.

It's hard to say this, but my interest in this topic has waned since the military-industrial complex got on board. C'est la vie.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 09/28/2016 08:20 AM
Agree - ESA could have conceivably been more enthusiastic about Skylon as the next-gen launch system. Instead, CNES ensured it would be Ariane 6.
I think ESA's as supportive as they could have been given they have a mandate to ensure European space access to members payloads.

SABRESkylons problem was always funding. As engineers they are very reluctant to sell what they don't have, unlike the computer industry, where this has been a regular occurrence.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Alpha_Centauri on 09/28/2016 10:45 AM
I'm sorry but the belief someone is just going to hand over $12 Billion-odd to develop the whole industrial chain for some vapourware is delusional in the extreme.

For Skylon to ever happen then the steps need to be reduced both in cost and risk. There needs to be an industrial chain working on hypersonic SABRE-based vehicles. Working on a more sensible scale grows that industry and makes the jump to Skylon less steep.


Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 09/28/2016 11:14 AM
I'm sorry but the belief someone is just going to hand over $12 Billion-odd to develop the whole industrial chain for some vapourware is delusional in the extreme.
And yet that's pretty much what LM are looking to do with the SR72.

However that was never REL's belief, as anyone who'd looked into them for more than five minutes would know.

REL have never been "given" funding. They have earned it because when fully funded they have delivered what they promised, roughly when they promised it.  Unlike the Chairman of BAE the Chairman of REL could not walk into the Prime Ministers office and ask how the application for government funding was going, nor could they threaten to close a factory unless they got the contract for some new piece of military kit which would perform with the usual level of efficiency for which BAE's products are justly known.  :(
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For Skylon to ever happen then the steps need to be reduced both in cost and risk.
What did you think the point of the full size pre cooler module demonstration was for exactly? The same question would apply to all the other side projects they have been involved in relating to other parts of the engine. 
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There needs to be an industrial chain working on hypersonic SABRE-based vehicles.
Actually there is, it's just not specific to Skylon (how could it be ?)
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Working on a more sensible scale grows that industry and makes the jump to Skylon less steep.
Something like the "sensibly" sized ITS perhaps?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Lars-J on 09/28/2016 07:50 PM
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Working on a more sensible scale grows that industry and makes the jump to Skylon less steep.
Something like the "sensibly" sized ITS perhaps?

Yes, but at least there the company has experience in developing launch vehicles, *and* have landed boosters. It is no larger jump really than the one from F1 to F9.

REL never did their F1.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: knowles2 on 09/28/2016 09:58 PM
Sadly it lack of ambition from UK investors means this engine and technology is likely end up buried in black programs and US secrecy.  :'(
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: knowles2 on 09/28/2016 10:19 PM
ITAR is Internation Traffic in Arms Regulations
https://en.wikipedia.org/wiki/International_Traffic_in_Arms_Regulations

It's complicated, so others may chime in, but in essence: since SABRE has clear military/missile applications, ITAR means once the US is involved 'exports' are prohibited, even to the UK, and even if it originated there.

EDIT:
It's not clear to me what would happen to test data gathered in the US. Would that be restricted to REL's US subsidiary?
Quote
Thanks for your reply.

I still don't understand the statement made by Mr Thomas. He says that an article designed and made in the UK may result in permanent relocation to the US and that that's a price worth paying. What exactly is he referring to by the word 'price' and why would it be worth paying? And what would this mean for transfer of proprietary knowledge?

I realise these are pretty basic, if not outright stupid, questions but it's driving me nuts trying to parse his words sans a proper grasp of ITAR/the industry.

Also, as this is only my second post, I'd just like to thank everybody for their contribution to this forum and thread - been a reader for a while.

I think he's just saying if testing had to be done in the US to convince the USAF to continue involvement and/or funding, then the 'price' of dealing with ITAR restrictions would be worth it. The price would not be in terms of cash but rather the hassle - and perhaps REL Ltd not even being able to see the results of tests performed on REL supplied hardware.
Let just hope they get planning permission for their new test facility, if a larger one is needed then the neccessary money to build one in somewhere like South Africa or Australia if there isn't the space in the UK.

Hopefully in a ideal world Rel in a couple of years can turn around to USAF and say if they want an engine to test they have to buy one, cost plus contracts, with a lot plus added on top to help Rel keep developing the technology.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: XaPi on 09/29/2016 02:30 AM
Hello,

this is my first post in this forum. I've been following this thread for years now, just reading. It accompanied me along my physics studies. I was thrilled by the Skylon idea. I would like to thank the participants of this discussion, I have learned a lot from you.

I must confess that I'm a little Bit sad that the Skylon project seems to have come to an end. Does anyone see a silver lining on the horizon? I mean, I'm not working for the aerospace industry, but I was always hoping for a regular space access in my lifetime.

Sorry for this quite emotional post. Greetings from Germany
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: ChrisWilson68 on 09/29/2016 03:33 AM
Welcome to the forum!

The silver lining is that both SpaceX and Blue Origin are well-funded, have built significant hardware that has flown successfully, and are aggressively targeting regular space access in the near future using completely reusable systems.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: momerathe on 09/29/2016 07:18 AM
I think the consensus is probably right in the near term. I've kinda suspected this would happen ever since the AFRL investigation was announced.

The silver lining is this: one the engine is in flight, and the technology is proved and working, investors will have a lot more confidence. Someone somewhere is going to look at it and say "Hey, we could use this for an SSTO". Whether we ever go full Skylon I don't know, but ultimately the goal of cheap access to space is bigger than any one vehicle.
Title: The Reaction Engines Skylon Master Thread (6)
Post by: Star One on 09/29/2016 12:11 PM
It's disappointing to see how much the Skylon project has been thwarted by lack of investor interest/confidence in it. I don't know if that's a particularly British issue or not.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 09/29/2016 12:30 PM
Hello,

this is my first post in this forum. I've been following this thread for years now, just reading. It accompanied me along my physics studies. I was thrilled by the Skylon idea. I would like to thank the participants of this discussion, I have learned a lot from you.

I must confess that I'm a little Bit sad that the Skylon project seems to have come to an end. Does anyone see a silver lining on the horizon? I mean, I'm not working for the aerospace industry, but I was always hoping for a regular space access in my lifetime.

Sorry for this quite emotional post. Greetings from Germany
Welcome to the forum from a Physics teacher! :) I would rather see the engine undergo testing by the USAF then the entire project just shelved forever. Many technologies that were once military do get to be used by the greater civilian population at large. Remember the common everyday jet engine we take for granted had their start by the military in both Germany and England. Stay positive, we never know for sure what the future has in store and exciting things keep happening in aerospace!
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: t43562 on 09/29/2016 12:39 PM
It must be because I am from the southern hemisphere or something but to be honest some naughty pejoratives (is that the word?) keep springing to mind about the attitude towards "things not being perfectly as I'd like them" that some from the mother country seem to have.

Up till now Skylon has been dead because they haven't been able to do anything about it other than talk and demonstrate some tubes.  I thought the 360 million (+-) that they claimed ot have lined up was likely to turn into crap because money that's promised is never to be counted on for more than microseconds  and I was depressed when that deficit became obvious about a year ago or slightly more because that really seemed like an end.

Now is when it starts to live. To me it seems the opposite way around - now their technology will step up the TRL levels and an SSTO becomes more likely rather than less.

I do like seeing the committed fans of other systems considerately holding your hands and directing you to the exit - that is really funny. :-)
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 09/29/2016 01:58 PM
The is an update article in Av-Week if you have access with eye-candy! :) Think SR-71 and a rocket powered D-21 drone with a cargo bay... 8)
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Alpha_Centauri on 09/29/2016 02:06 PM
Don't tar all of us Motherlanders with the same brush.  ;)

Some people seem to be, how shall I put it, a little melodramatic.  For a start the Skylon project isn't ending, it never started seriously in the first place after decades of ramping.

The article says absolutely nothing about giving up their dream of Skylon, indeed it talks about the demonstrator being modular so they can grow the capability. The only thing that has changed is realising to get off the ground the SABRE cycle needs to appeal to a variety of investors. That is a positive thing!

Btw I suggest that they appear to be hinting using SABRE 3 as the demonstrator is precisely because they want to protect SABRE 4.

Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RonM on 09/29/2016 03:07 PM
It must be because I am from the southern hemisphere or something but to be honest some naughty pejoratives (is that the word?) keep springing to mind about the attitude towards "things not being perfectly as I'd like them" that some from the mother country seem to have.

Up till now Skylon has been dead because they haven't been able to do anything about it other than talk and demonstrate some tubes.  I thought the 360 million (+-) that they claimed ot have lined up was likely to turn into crap because money that's promised is never to be counted on for more than microseconds  and I was depressed when that deficit became obvious about a year ago or slightly more because that really seemed like an end.

Now is when it starts to live. To me it seems the opposite way around - now their technology will step up the TRL levels and an SSTO becomes more likely rather than less.

I do like seeing the committed fans of other systems considerately holding your hands and directing you to the exit - that is really funny. :-)

Yes, with research money from the USAF, SABRE technology will be tested. That brings us closer to Skylon or something like it in the future.

Some people might be upset that SABRE has been sold out to the "American Empire" but who other than the Pentagon could afford to do this? Last time I checked the US was still an ally of the UK.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 09/29/2016 03:16 PM
Look at the life the Harrier went on to live in expanded uses, versions and upgrades...
https://en.wikipedia.org/wiki/Hawker_Siddeley_Harrier
http://www.boeing.com/history/products/av-8-harrier-ii.page
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: CrewtaiL on 09/29/2016 04:08 PM
It must be because I am from the southern hemisphere or something but to be honest some naughty pejoratives (is that the word?) keep springing to mind about the attitude towards "things not being perfectly as I'd like them" that some from the mother country seem to have.

Up till now Skylon has been dead because they haven't been able to do anything about it other than talk and demonstrate some tubes.  I thought the 360 million (+-) that they claimed ot have lined up was likely to turn into crap because money that's promised is never to be counted on for more than microseconds  and I was depressed when that deficit became obvious about a year ago or slightly more because that really seemed like an end.

Now is when it starts to live. To me it seems the opposite way around - now their technology will step up the TRL levels and an SSTO becomes more likely rather than less.

I do like seeing the committed fans of other systems considerately holding your hands and directing you to the exit - that is really funny. :-)

Yes, with research money from the USAF, SABRE technology will be tested. That brings us closer to Skylon or something like it in the future.

Some people might be upset that SABRE has been sold out to the "American Empire" but who other than the Pentagon could afford to do this? Last time I checked the US was still an ally of the UK.

There's no way the UK would be stupid enough to give this technology to another country, even one as friendly as the US, especially post-Brexit.

The same way the US refuses to sell the F22 to allies, instead offering the F35, and even then without access to the software code/proprietary knowledge, the UK should make available, say, the Sabre 2/3 variant only, and preclude all transfer of technical know-how.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Alpha_Centauri on 09/29/2016 04:13 PM
That's what should happen, but it doesn't. That's why some posters are worried about this, I don't blame them that. Modern history is littered with technology that was invented here that one way or another the US took and sold the developed product back to us.

But frankly there is no other way Skylon is going to happen.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 09/29/2016 04:22 PM
There's no way the UK would be stupid enough to give this technology to another country, even one as friendly as the US, especially post-Brexit.
"The UK" is the British Government. They did not develop this technology and they barely (belatedly) part funded it, with AFAIK no control of the IP.

They cannot therefor stop it happening. When Bond developed the original cycle while working for Rolls Royce the UK Govt of the time classified it so it could not be talked about and RR could not get non British partners. REL spent a lot of effort designing around the patent, making it much more efficient in the process.
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The same way the US refuses to sell the F22 to allies, instead offering the F35, and even then without access to the software code/proprietary knowledge, the UK should make available, say, the Sabre 2/3 variant only, and preclude all transfer of technical know-how.
The mfg process for the pre cooler is very complex and is a critical technology. Designing a heat exchanger to extract X watts in a size of Y Kg is fairly easy. Implementing it is much tougher.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: CrewtaiL on 09/29/2016 05:25 PM
There's no way the UK would be stupid enough to give this technology to another country, even one as friendly as the US, especially post-Brexit.
"The UK" is the British Government. They did not develop this technology and they barely (belatedly) part funded it, with AFAIK no control of the IP.

They cannot therefor stop it happening. When Bond developed the original cycle while working for Rolls Royce the UK Govt of the time classified it so it could not be talked about and RR could not get non British partners. REL spent a lot of effort designing around the patent, making it much more efficient in the process.
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The same way the US refuses to sell the F22 to allies, instead offering the F35, and even then without access to the software code/proprietary knowledge, the UK should make available, say, the Sabre 2/3 variant only, and preclude all transfer of technical know-how.
The mfg process for the pre cooler is very complex and is a critical technology. Designing a heat exchanger to extract X watts in a size of Y Kg is fairly easy. Implementing it is much tougher.

What about the EU's arms embargo on China?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: t43562 on 09/29/2016 07:54 PM
The Government have shown no interest thus far in stopping REL from doing deals in the US and I think this is great. It's their idea, their glory, their effort and they get to do with it as they see fit. If we taxpayers have a lot of other priorities and no further way to assist then we should at least not be blocking them. 

I bet Britain has benefited a great deal in history from being a place where people (like me) bring their ideas to have a better chance than at home.

It amuses me to remember that Elon Musk is from Johannesburg. Why isn't he doing SpaceX back in South Africa? Should South Africans have a long moan about how their innovations/innovators get nicked by "the big countries"? Obviously not, he did the right thing and went to where he had a chance in hell of doing what interested him.

 
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 09/29/2016 08:26 PM
The Wright brothers tried to get the US government interested in their aircraft and finally said fine we'll take it to Europe. France was really interested and you know what? The first American pilots flew French planes as America had no top line fighters, just training aircraft in WWI...
https://airandspace.si.edu/exhibitions/wright-brothers/online/age/1908/europe.cfm
https://www.youtube.com/watch?v=ff2D-yLt830

Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: XaPi on 09/30/2016 07:42 PM
Thank you for your encouraging replies. Maybe I should be more open for the other projects being developed at the moment. Like Blue Origin's and SpaceX' ones mentioned by ChrisWilson. (I'm not that thrilled by those, since they don't match the OrionIII style of space odyssey. But that's my personal problem ;) )

On the other hand I admit that if the SABRE tech. survives and gets tested by the airforce, there is at least some hope that it might be used by a real space-plane. I just hoped the full space-plane was an earlier step. Ok I'll be patient again. (I hope it doesen't turn out to be a story like nuclear-fusion with its 50 year time constant). From a physicist's point of view the SABRE cycle is very interesting, so I stay tuned...
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 10/03/2016 04:20 PM
The Wright brothers tried to get the US government interested in their aircraft and finally said fine we'll take it to Europe. France was really interested and you know what? The first American pilots flew French planes as America had no top line fighters, just training aircraft in WWI...

The US aviation situation was a direct result of the Wright's patent litigations, (specifically the fight with Curtiss but also a general attempt to gain a 10 year monopoly through those patents) That fell flat outside the US with most nations refusing to pursue the numerous Wright "patent infringement" cases against their own innovators. And the reason the Army was less than thrilled with the Wright flier and requested significant changes, and upgrades but the Wrights were not interested in "improving" the flier until they had the patents and monopoly and did not pursue significant changes until after numerous other American innovators had done so.

Meanwhile anyone who produced or flew an "aircraft" in the United States was taken to court by the Wright company, (often as an extension and supplement to the on-going Curtis-Wright cases) and in fact Europeans who came to the US or shared information were legally attacked as well.

The case has been set out a number of times that the Wright's managed to be the recognized 'first to fly' and then spent the next 10 years ensuring the US aviation technology would be decades behind the rest of the world.

This lesson was learned again here in the US during early rocket work where the various groups and individuals involved not only had differing ideas on what the future of US rocketry should look like they also spent great amounts of time and effort patenting (and fighting patent battles) as much of their work as possible while simultaneously criticizing everyone else's ideas and work, yet trying to 'cooperate' so they could see what everyone else was working on. It only got slightly better during WWII when the military forced cooperation and sharing of information because of the prior experience with the Wright's and aviation.

How does this relate to Skylon, SABRE, REL and Europe or the US? It really doesn't, but actually the basic heart of the situation is that new technology, new methods, and new concepts are quite often not fully understood or appreciated at the time or place they are introduced. The reasons can be varied and numerous and can come from any number of places but in the end perseverance and demonstration tend to be the biggest determining factors which drive recognition and thence acceptance. REL seems on the right track since they have a lot of bias and doubt to overcome.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 10/04/2016 12:41 AM
The Wright brothers tried to get the US government interested in their aircraft and finally said fine we'll take it to Europe. France was really interested and you know what? The first American pilots flew French planes as America had no top line fighters, just training aircraft in WWI...

The US aviation situation was a direct result of the Wright's patent litigations, (specifically the fight with Curtiss but also a general attempt to gain a 10 year monopoly through those patents) That fell flat outside the US with most nations refusing to pursue the numerous Wright "patent infringement" cases against their own innovators. And the reason the Army was less than thrilled with the Wright flier and requested significant changes, and upgrades but the Wrights were not interested in "improving" the flier until they had the patents and monopoly and did not pursue significant changes until after numerous other American innovators had done so.

Meanwhile anyone who produced or flew an "aircraft" in the United States was taken to court by the Wright company, (often as an extension and supplement to the on-going Curtis-Wright cases) and in fact Europeans who came to the US or shared information were legally attacked as well.

The case has been set out a number of times that the Wright's managed to be the recognized 'first to fly' and then spent the next 10 years ensuring the US aviation technology would be decades behind the rest of the world.

This lesson was learned again here in the US during early rocket work where the various groups and individuals involved not only had differing ideas on what the future of US rocketry should look like they also spent great amounts of time and effort patenting (and fighting patent battles) as much of their work as possible while simultaneously criticizing everyone else's ideas and work, yet trying to 'cooperate' so they could see what everyone else was working on. It only got slightly better during WWII when the military forced cooperation and sharing of information because of the prior experience with the Wright's and aviation.

How does this relate to Skylon, SABRE, REL and Europe or the US? It really doesn't, but actually the basic heart of the situation is that new technology, new methods, and new concepts are quite often not fully understood or appreciated at the time or place they are introduced. The reasons can be varied and numerous and can come from any number of places but in the end perseverance and demonstration tend to be the biggest determining factors which drive recognition and thence acceptance. REL seems on the right track since they have a lot of bias and doubt to overcome.

Randy
We already talked about this a a few months back, so no need for the history lesson... My point is to those who feel upset that the technology project is going to the US. The fact is if your home nation won't back you would you rather see your hard work never take flight on a point of pride...
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Lampyridae on 10/04/2016 08:50 AM
Back to topic.

If you want the tech developed, you have to take it where there will be the money and backing to get it developed. SpaceX is where it is thanks to NASA and the USAF. Blue Origin is no exception, and they still have a relationship with NASA and a big one with the USAF.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 10/04/2016 03:32 PM
We already talked about this a a few months back, so no need for the history lesson... My point is to those who feel upset that the technology project is going to the US. The fact is if your home nation won't back you would you rather see your hard work never take flight on a point of pride...

Those who do not learn from history... and all that :) But it's a general point that there are a LOT of various concepts and technologies out there that have been at the same point as Skylon/SABRE/REL that still haven't gone anywhere not only because the 'home' nation isn't interested but because the work has been classified or otherwise restricted. In many cases it is simply that knowledge isn't well known or documented in any open places which means even if someone else was willing to work in it you still have to start from scratch.

It's frustrating to the extreme but you are very correct in asking how much you're willing to put up with to see the technology in use. However, I'd point out the cautionary tales of OTRAG and Gerald Bull :)

Back to topic.

If you want the tech developed, you have to take it where there will be the money and backing to get it developed. SpaceX is where it is thanks to NASA and the USAF. Blue Origin is no exception, and they still have a relationship with NASA and a big one with the USAF.

But I can understand the hesitancy since they also have a point that once in the system in the US it becomes much more complicated to extract and share the subsequent knowledge due to things like ITAR and security concerns. In addition there is the concern about loosing control or participation as the program morphs due to outside influences you no longer have control over. (In the case of SABRE seeing it attached to some SCramjet requirements due to some arcane inserted requirement is a very real possibility should the program move towards flight status. Having the engine use in a TSTO design is no guarantee of such an addition not being forced on the concept at a later date)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 10/04/2016 09:50 PM
Come-on Randy, is the U.S. some rogue government in you eyes now?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 10/04/2016 09:55 PM
Meanwhile anyone who produced or flew an "aircraft" in the United States was taken to court by the Wright company, (often as an extension and supplement to the on-going Curtis-Wright cases) and in fact Europeans who came to the US or shared information were legally attacked as well.
And now they call it ITAR...  :(
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How does this relate to Skylon, SABRE, REL and Europe or the US? It really doesn't, but actually the basic heart of the situation is that new technology, new methods, and new concepts are quite often not fully understood or appreciated at the time or place they are introduced. The reasons can be varied and numerous and can come from any number of places but in the end perseverance and demonstration tend to be the biggest determining factors which drive recognition and thence acceptance. REL seems on the right track since they have a lot of bias and doubt to overcome.
Indeed.
It's frustrating to the extreme but you are very correct in asking how much you're willing to put up with to see the technology in use. However, I'd point out the cautionary tales of OTRAG and Gerald Bull :)
Quite.
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If you want the tech developed, you have to take it where there will be the money and backing to get it developed. SpaceX is where it is thanks to NASA and the USAF. Blue Origin is no exception, and they still have a relationship with NASA and a big one with the USAF.
And they would have an equally large task if they decided they wanted to operate anywhere outside the US.
Quote
But I can understand the hesitancy since they also have a point that once in the system in the US it becomes much more complicated to extract and share the subsequent knowledge due to things like ITAR and security concerns. In addition there is the concern about loosing control or participation as the program morphs due to outside influences you no longer have control over. (In the case of SABRE seeing it attached to some SCramjet requirements due to some arcane inserted requirement is a very real possibility should the program move towards flight status. Having the engine use in a TSTO design is no guarantee of such an addition not being forced on the concept at a later date)
True, despite no evidence SCramjets are anywhere  near viable for anything except a missile system. I note that its T/W is as good as the J58 inside its nacelle on the SR71 but this ignores the fact the J58's could fly the whole mission without a large rocket motor to accelerate them to operating speed. With that weight factored in I'd guess their T/W is maybe 1.5:1 or less. And of course it's a one shot system.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: francesco nicoli on 10/04/2016 10:03 PM
Meanwhile anyone who produced or flew an "aircraft" in the United States was taken to court by the Wright company, (often as an extension and supplement to the on-going Curtis-Wright cases) and in fact Europeans who came to the US or shared information were legally attacked as well.
And now they call it ITAR...  :(
Quote
How does this relate to Skylon, SABRE, REL and Europe or the US? It really doesn't, but actually the basic heart of the situation is that new technology, new methods, and new concepts are quite often not fully understood or appreciated at the time or place they are introduced. The reasons can be varied and numerous and can come from any number of places but in the end perseverance and demonstration tend to be the biggest determining factors which drive recognition and thence acceptance. REL seems on the right track since they have a lot of bias and doubt to overcome.
Indeed.
It's frustrating to the extreme but you are very correct in asking how much you're willing to put up with to see the technology in use. However, I'd point out the cautionary tales of OTRAG and Gerald Bull :)
Quite.
Quote
If you want the tech developed, you have to take it where there will be the money and backing to get it developed. SpaceX is where it is thanks to NASA and the USAF. Blue Origin is no exception, and they still have a relationship with NASA and a big one with the USAF.
And they would have an equally large task if they decided they wanted to operate anywhere outside the US.
Quote
But I can understand the hesitancy since they also have a point that once in the system in the US it becomes much more complicated to extract and share the subsequent knowledge due to things like ITAR and security concerns. In addition there is the concern about loosing control or participation as the program morphs due to outside influences you no longer have control over. (In the case of SABRE seeing it attached to some SCramjet requirements due to some arcane inserted requirement is a very real possibility should the program move towards flight status. Having the engine use in a TSTO design is no guarantee of such an addition not being forced on the concept at a later date)
True, despite no evidence SCramjets are anywhere  near viable for anything except a missile system. I note that its T/W is as good as the J58 inside its nacelle on the SR71 but this ignores the fact the J58's could fly the whole mission without a large rocket motor to accelerate them to operating speed. With that weight factored in I'd guess their T/W is maybe 1.5:1 or less. And of course it's a one shot system.

Or maybe all this will work as a wake-up call for Britain and the EU to stop discussing about meaningless stuff because the world out there is not waiting for them to sort out whether polish medics should be able to heal british patients or not.
Honestly, our leadership and a great share of our population is so much taken by silly stuff that if we end up losing this technology, we totally deserved it. Instead of partnering up to open the skyes, we have spent our energy, time and money in building brickwalls & ideological barriers. We play the 19th century game and not the 21st one. Thererfore, we got precisely what we deserve.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 10/04/2016 10:28 PM
Come-on Randy, is the U.S. some rogue government in you eyes now?

What do you mean "now"? :)
(And lest we forget I've worked for 'them' for almost my entire adult life so I may be speaking a bit from experience :) )

And not in that way, no. But the US actually has a history of being quite A-Retentive about technology both internally and externally with the "we invented everything" and the "not invented here" as co-existing paradigms.

The military are no angels but they do tend to favor practicality over theory when it doesn't come directly to funding depending on the latest and greatest. it's not a question of 'rouge' really but of historic relevance issues. On the main the US isn't that bad but it CAN and has been in the past so it is understandable why some would be disappointed that they may in fact be the saviors of their dreams :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 10/04/2016 10:38 PM
Or maybe all this will work as a wake-up call for Britain and the EU to stop discussing about meaningless stuff because the world out there is not waiting for them to sort out whether polish medics should be able to heal british patients or not.
Honestly, our leadership and a great share of our population is so much taken by silly stuff that if we end up losing this technology, we totally deserved it. Instead of partnering up to open the skyes, we have spent our energy, time and money in building brickwalls & ideological barriers. We play the 19th century game and not the 21st one. Thererfore, we got precisely what we deserve.

Going to point out that IF it is considered a 'meaningful' issue with a large segment of the population then it is going to be a 'meaningful' issue with the politicians by default.

Space access, exploration, and all what most of us here consider 'meaningful' is not so with the majority of the population and forgetting that we tend to see other issues as meaning-less for that reason. There is no arguing that a large majority of the populations around the world are always going to see closer, and more immediate 'issues' as priorities and therefore their politicians will as well.

This won't shift much, (if at all) until something makes space a more significant issue and frankly it that happens it will probably be too late for it to be a game changing issue. (By definition a looming threat of say an civilization ending asteroid impact that significantly focus' civilizations attention will occur at time when it will be far to late to do much of anything about it if you don't already have the means to deal with it)

But on subject it simply means that neither Europe nor England have enough internal cohesion and resources to get Skylon and/or SABRE to the point of practical demonstration where as the US does in fact have both IF you can avoid the various obstacles that dealing with the US presents.

REL while admitting they think their concept is better at least realizes this situation provides them with opportunities they can't get 'at home' and is willing to take their chances. I can't say as I disagree with them on this.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Asteroza on 10/04/2016 11:15 PM
Whether we ever go full Skylon ...

AFRL: Never go full Skylon...
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Star One on 10/05/2016 01:20 PM
Meanwhile anyone who produced or flew an "aircraft" in the United States was taken to court by the Wright company, (often as an extension and supplement to the on-going Curtis-Wright cases) and in fact Europeans who came to the US or shared information were legally attacked as well.
And now they call it ITAR...  :(
Quote
How does this relate to Skylon, SABRE, REL and Europe or the US? It really doesn't, but actually the basic heart of the situation is that new technology, new methods, and new concepts are quite often not fully understood or appreciated at the time or place they are introduced. The reasons can be varied and numerous and can come from any number of places but in the end perseverance and demonstration tend to be the biggest determining factors which drive recognition and thence acceptance. REL seems on the right track since they have a lot of bias and doubt to overcome.
Indeed.
It's frustrating to the extreme but you are very correct in asking how much you're willing to put up with to see the technology in use. However, I'd point out the cautionary tales of OTRAG and Gerald Bull :)
Quite.
Quote
If you want the tech developed, you have to take it where there will be the money and backing to get it developed. SpaceX is where it is thanks to NASA and the USAF. Blue Origin is no exception, and they still have a relationship with NASA and a big one with the USAF.
And they would have an equally large task if they decided they wanted to operate anywhere outside the US.
Quote
But I can understand the hesitancy since they also have a point that once in the system in the US it becomes much more complicated to extract and share the subsequent knowledge due to things like ITAR and security concerns. In addition there is the concern about loosing control or participation as the program morphs due to outside influences you no longer have control over. (In the case of SABRE seeing it attached to some SCramjet requirements due to some arcane inserted requirement is a very real possibility should the program move towards flight status. Having the engine use in a TSTO design is no guarantee of such an addition not being forced on the concept at a later date)
True, despite no evidence SCramjets are anywhere  near viable for anything except a missile system. I note that its T/W is as good as the J58 inside its nacelle on the SR71 but this ignores the fact the J58's could fly the whole mission without a large rocket motor to accelerate them to operating speed. With that weight factored in I'd guess their T/W is maybe 1.5:1 or less. And of course it's a one shot system.

Or maybe all this will work as a wake-up call for Britain and the EU to stop discussing about meaningless stuff because the world out there is not waiting for them to sort out whether polish medics should be able to heal british patients or not.
Honestly, our leadership and a great share of our population is so much taken by silly stuff that if we end up losing this technology, we totally deserved it. Instead of partnering up to open the skyes, we have spent our energy, time and money in building brickwalls & ideological barriers. We play the 19th century game and not the 21st one. Thererfore, we got precisely what we deserve.

I don't see this happening being as we look headed for a so called hard Brexit from the EU.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Ravenger on 10/05/2016 02:46 PM
I don't see this happening being as we look headed for a so called hard Brexit from the EU.

I'd love to see Skylon adopted by ESA as their preferred launcher, but that's not going to happen due to politics which have absolutely nothing to do with Brexit, which existed before we even considered a referendum.

In any case, ESA is not an EU organisation, though there is some EU involvement in ESA. Countries outside the EU make considerable contributions to ESA, so a 'Hard' (I prefer 'Clean') Brexit shouldn't make much of a difference to ESA involvement. The drop in the pound's value makes our manufacturing more competive anyway.

In fact, EU state aid rules considerably delayed the (minimal) UK government investment in REL, and may have been a factor in REL having to get BAE to buy a stake in the company, and thereby changing the direction of travel towards military rather than civilian applications of SABRE.

Out of the EU the British Government would be able to invest more freely in REL, though I think that's extremely unlikely.

I'm very disappointed in UK investors and the British Government for not investing more highly in REL. It's not surprising that REL are now looking towards the US and the US Military in particular as it's the only way they can get the funding to continue development. Like most of us on here, I'd rather see SABRE fully developed even if it has to go to the US to do it - though it really hurts that it can't be fully funded in the UK or Europe.




Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: jrc14 on 10/05/2016 02:47 PM
I don't see this happening being as we look headed for a so called hard Brexit from the EU.
Not so long ago, the mods had to prune a whole load of Brexit nonsense out of this thread.  Please do not put them to the trouble again.  I can understand that you want to give the world the benefit of your opinion on this subject, but there are plenty of other places on the internet for you do to that; please use one of them.
And let's keep this forum free for focussed discussion on REL, SABRE and Skylon.
Title: The Reaction Engines Skylon Master Thread (6)
Post by: Star One on 10/05/2016 03:04 PM
I don't see this happening being as we look headed for a so called hard Brexit from the EU.
Not so long ago, the mods had to prune a whole load of Brexit nonsense out of this thread.  Please do not put them to the trouble again.  I can understand that you want to give the world the benefit of your opinion on this subject, but there are plenty of other places on the internet for you do to that; please use one of them.
And let's keep this forum free for focussed discussion on REL, SABRE and Skylon.

I wasn't the one who brought the EU into this conversation need I remind you. Maybe you should try complaining to the poster who started the drift rather than me?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: jrc14 on 10/05/2016 03:15 PM
I wasn't the one who brought the EU into this conversation need I remind you. Maybe you should try complaining to the poster who started the drift rather than me?
Sorry - I did not mean to imply that you were the only person to blame for bringing 'Brexit' into the conversation - and of course, it is perfectly reasonable to debate, in this thread, the politics around which governments and other organisations might fund REL/SABRE/Skylon.  It's just that I foresee this thread heading back into a Brexit-inspired death-spiral, and that doesn't seem like a smart idea.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: CrewtaiL on 10/05/2016 03:27 PM
I don't see this happening being as we look headed for a so called hard Brexit from the EU.

I'd love to see Skylon adopted by ESA as their preferred launcher, but that's not going to happen due to politics which have absolutely nothing to do with Brexit, which existed before we even considered a referendum.

In any case, ESA is not an EU organisation, though there is some EU involvement in ESA. Countries outside the EU make considerable contributions to ESA, so a 'Hard' (I prefer 'Clean') Brexit shouldn't make much of a difference to ESA involvement. The drop in the pound's value makes our manufacturing more competive anyway.

In fact, EU state aid rules considerably delayed the (minimal) UK government investment in REL, and may have been a factor in REL having to get BAE to buy a stake in the company, and thereby changing the direction of travel towards military rather than civilian applications of SABRE.

Out of the EU the British Government would be able to invest more freely in REL, though I think that's extremely unlikely.

I'm very disappointed in UK investors and the British Government for not investing more highly in REL. It's not surprising that REL are now looking towards the US and the US Military in particular as it's the only way they can get the funding to continue development. Like most of us on here, I'd rather see SABRE fully developed even if it has to go to the US to do it - though it really hurts that it can't be fully funded in the UK or Europe.

I will bet everything I have the British military is involved with this tech. already. The fact that BAE is in the mix only reinforces my belief.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: lkm on 10/05/2016 04:01 PM
I don't see this happening being as we look headed for a so called hard Brexit from the EU.

I'd love to see Skylon adopted by ESA as their preferred launcher, but that's not going to happen due to politics which have absolutely nothing to do with Brexit, which existed before we even considered a referendum.

In any case, ESA is not an EU organisation, though there is some EU involvement in ESA. Countries outside the EU make considerable contributions to ESA, so a 'Hard' (I prefer 'Clean') Brexit shouldn't make much of a difference to ESA involvement. The drop in the pound's value makes our manufacturing more competive anyway.

In fact, EU state aid rules considerably delayed the (minimal) UK government investment in REL, and may have been a factor in REL having to get BAE to buy a stake in the company, and thereby changing the direction of travel towards military rather than civilian applications of SABRE.

Out of the EU the British Government would be able to invest more freely in REL, though I think that's extremely unlikely.

I'm very disappointed in UK investors and the British Government for not investing more highly in REL. It's not surprising that REL are now looking towards the US and the US Military in particular as it's the only way they can get the funding to continue development. Like most of us on here, I'd rather see SABRE fully developed even if it has to go to the US to do it - though it really hurts that it can't be fully funded in the UK or Europe.

I will bet everything I have the British military is involved with this tech. already. The fact that BAE is in the mix only reinforces my belief.
Well yeah, it predates AFRL involvement.
http://www.reactionengines.co.uk/news_17aug2015_rel_dstl.html
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 10/05/2016 04:16 PM
In fact, EU state aid rules considerably delayed the (minimal) UK government investment in REL, and may have been a factor in REL having to get BAE to buy a stake in the company, and thereby changing the direction of travel towards military rather than civilian applications of SABRE.


Out of the EU the British Government would be able to invest more freely in REL, though I think that's extremely unlikely.

I'm very disappointed in UK investors and the British Government for not investing more highly in REL. It's not surprising that REL are now looking towards the US and the US Military in particular as it's the only way they can get the funding to continue development. Like most of us on here, I'd rather see SABRE fully developed even if it has to go to the US to do it - though it really hurts that it can't be fully funded in the UK or Europe.
UK private investors got REL a lot further than companies this side normally get.  The UK corporate sector does not seem to have been very helpful but REL's business plan was always going to be very difficult as effectively they wanted to be a 2nd tier supplier to a vehicle. Engineers tend to have linear minds and this was a problem that needed a non-linear solution. You have a company (REL) that's gearing up to make a part, a substantial market for a vehicle (if you can get it built) and a big hole in between.

Unless REL can solve that "big hole in between" problem this TSTO looks the closest SABRE will get to flight, and note it's still a concept, not a programme yet. This could be left with the USAF providing no further funding and REL so enmeshed in US ITAR regulations they cannot pursue any other funding.

Much as Bond was when the UK Govt classified the original RR 545 design patents, making any conversation with any other investors impossible.

Those familiar with the background may recall BAE and the "Multi Role Capsule" saga and would view BAE's involvement as a very mixed blessing.  :(
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 10/05/2016 05:39 PM
If you want the tech developed, you have to take it where there will be the money and backing to get it developed. SpaceX is where it is thanks to NASA and the USAF. Blue Origin is no exception, and they still have a relationship with NASA and a big one with the USAF.
And they would have an equally large task if they decided they wanted to operate anywhere outside the US.

Just so we're clear that was Lampyridae's comment not mine I was quoting him :)
Quote
Quote
But I can understand the hesitancy since they also have a point that once in the system in the US it becomes much more complicated to extract and share the subsequent knowledge due to things like ITAR and security concerns. In addition there is the concern about loosing control or participation as the program morphs due to outside influences you no longer have control over. (In the case of SABRE seeing it attached to some SCramjet requirements due to some arcane inserted requirement is a very real possibility should the program move towards flight status. Having the engine use in a TSTO design is no guarantee of such an addition not being forced on the concept at a later date)
True, despite no evidence SCramjets are anywhere  near viable for anything except a missile system. I note that its T/W is as good as the J58 inside its nacelle on the SR71 but this ignores the fact the J58's could fly the whole mission without a large rocket motor to accelerate them to operating speed. With that weight factored in I'd guess their T/W is maybe 1.5:1 or less. And of course it's a one shot system.

Well really that's why suggesting a TSTO makes some sense because there is more chance with an SSTO concept that SOMEONE is going to throw a SCramjet on it. The main problem is the SCramjet SHOULD be rather simple given it is a variant of the ramjet which, (when you get down to the very basics) for intents and purposes is a simple tube after all. The theory is tempting in that you should then be able to use a system that can be both a subsonic and supersonic ramjet in the same "engine" (hence the dual-mode SCramjet designs) to which you only need attach a zero-to-supersonic accelerator and you have what amounts to the "perfect" air breathing engine.

That 'theory' has been running into several 'brick-walls' of reality for over 50 years now and really we should be looking at the bigger picture. Unfortunately if you look at it under the right light and 'squint' really good it would appear that, much like viable nuclear fusion power, SCramjets will obviously be "ready" any year now. The fact that this is based on questionable to say the least assumptions is ignored.

The theory/dream that a SCramjet engine will allow "economical-and-easy" zero to beyond orbital speed is essentially "true" for certain values of the definition of "truth" but really the obvious engineering and practical applications issues that logically follow along that line of thinking which are just as obviously being ignored in order to not fully question the end goal.

Since it is obvious that you do not in fact "require" SCramjet engines to economically propel a surface-to-orbit vehicle the very first requirement would seem to be to NOT assume that a SCramjet is required in the first place, but as I keep pointing out, no one cares what I think :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 10/05/2016 05:50 PM
Whether we ever go full Skylon ...

AFRL: Never go full Skylon...

The AF and AFRL have actually considered and studied SSTO vehicles both rocket and combined cycle powered numerous times. There are operational and military advantages to a TSTO system so it's more often at least the initial concept though. Considering that the key interest here is the SABRE and it's cycle going with a TSTO greatly reduces the chances of someone trying to tack on a SCramjet research program onto the system I suspect :)

So I'd say "never" isn't something to assume since frankly while Skylon is a viable early design I can think of a bunch of operational (both military and commercial) and military design considerations that REL missed because of different initial assumptions.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Star One on 10/05/2016 07:10 PM
I wasn't the one who brought the EU into this conversation need I remind you. Maybe you should try complaining to the poster who started the drift rather than me?
Sorry - I did not mean to imply that you were the only person to blame for bringing 'Brexit' into the conversation - and of course, it is perfectly reasonable to debate, in this thread, the politics around which governments and other organisations might fund REL/SABRE/Skylon.  It's just that I foresee this thread heading back into a Brexit-inspired death-spiral, and that doesn't seem like a smart idea.

Fair enough. You're right in that maybe as much as possible we should keep away from UK domestic politics in this thread.

I suspect UK politics will not be in the driving seat much longer with this project and that it will be very much a US driven item going forward.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 10/05/2016 07:47 PM
In fact, EU state aid rules considerably delayed the (minimal) UK government investment in REL, and may have been a factor in REL having to get BAE to buy a stake in the company, and thereby changing the direction of travel towards military rather than civilian applications of SABRE.

This is something that needs to be addressed as it keep popping up, mostly because it is the "Air Force" Research Laboratory that REL is working with.

The "application" of the SABRE has NOT changed a bit, it has always had as much military as civilian application no matter what. It is and always has been a PROPULSION system and by their nature how exactly they are used is literally a "user" decision. The basic fact that SABRE was proposed and designed as a 'surface-to-orbit/space' engine in no way defines its role or use since that mission has both commercial and military applications.

The US Air Force through AFRL is paying to study the use(s) of the SABRE cycle for the same mission(s) they have studied many other propulsion systems which include the Merlin rocket engine and tubro-charger based jet engines. The main suggestion is that any and all of them may have a military purpose but in general the 'job' is to propel an asset and not specifically on a military or commercial mission. Being's it's the Air Force they ARE going to point out the obvious "military" possible missions but in general they correspond to similar commercial applications and/or missions.

I think an obvious 'omission' from the study was any suggestion of using the proposed TSTO for the 'rapid global strike' mission and a focus on orbital delivery would have been a clue that the military aspect was deliberately downplayed in the study.

Quote
I'm very disappointed in UK investors and the British Government for not investing more highly in REL. It's not surprising that REL are now looking towards the US and the US Military in particular as it's the only way they can get the funding to continue development. Like most of us on here, I'd rather see SABRE fully developed even if it has to go to the US to do it - though it really hurts that it can't be fully funded in the UK or Europe.

Don't see how this is a supported point of view actually. Private and government investment, (as JS19 points out) was more than received by previous proposals but in-line with what is really a 'high-risk' and unproven system that MAY lead to an SSTO vehicle that may match current market requirements. (As I keep pointing out a Skylon SSTO, by itself, will not meet market requirements and REL has consistently noted this and the various additive requirements to fully meet those requirements. JUST having Skylon is not enough and THAT in and of itself requires a large upfront investment that might not actually 'pay-off' in the first place. Skylon/SABRE is unproven at this point and as JS10 notes there's a large 'gap' that needs to be covered to get the point where it would be as 'atractive' an investment as something already proven and with a known history)

UK private investors got REL a lot further than companies this side normally get.  The UK corporate sector does not seem to have been very helpful but REL's business plan was always going to be very difficult as effectively they wanted to be a 2nd tier supplier to a vehicle. Engineers tend to have linear minds and this was a problem that needed a non-linear solution. You have a company (REL) that's gearing up to make a part, a substantial market for a vehicle (if you can get it built) and a big hole in between.

Unless REL can solve that "big hole in between" problem this TSTO looks the closest SABRE will get to flight, and note it's still a concept, not a programme yet.

That! The thing is a 'working' (even a non-flight model) SABRE significantly increases confidence that the rest of "Skylon" (or other concepts) will be possible and therefor the whole thing may actually be the 'game changer' that it obviously would be.

The thing is the whole 'game changer' idea has been overplayed and the record so far has far less 'successful' than failures and that increase the burden and bar for 'proof' that has to be met.

Quote
This could be left with the USAF providing no further funding and REL so enmeshed in US ITAR regulations they cannot pursue any other funding.

I'm pretty sure that REL won't have that problem even if no further support is found in the US. If someone were to try and apply ITAR in a encompassing fashion I'm confident that ITAR will end up loosing that particular battle as REL has a deep patent and 'prior-work' base to draw from in its defense.

Quote
Much as Bond was when the UK Govt classified the original RR 545 design patents, making any conversation with any other investors impossible.

Totally different situation actually as the RR545 was designed UNDER a government contract which by definition allows the government to do what it wants with the end-product. In this case SABRE is very much an outside property over which the Air Force and US Government has no claim. As long as there are no significant changes to the cycle or engine, (and I see nothing in the study or has been suggested) then the entire 'interface' is simply plugging the SABRE into a design concept in the same manner as any other 'propulsion' system. Even if the AFRL were to support and build a 'testbed' system they are limited to what they can 'classify' other than in general because the SABRE is an existing and publicly known engine system even if not 'proven' in operation.

And frankly I'm going to have to get up on my high-horse and berate everyone who is 'disappointed' about REL having to work with the US Air Force to move SABRE forward. :)

Y'all have NO room to complain. Not a single 'leg' to stand on. You have NO idea how frustrating, disappointing, rage-inducing, oh go ahead and throw a thesaurus in here on "let-down-ungentle" concepts while we're at it. :)

Here's a bit of historic perspective for you all; EVERYTHING that has gone into the SABRE engine concept was INVENTED, STUDIED, and IGNORED in the United States prior to 1965 and while the more advanced heat exchanger itself is highly impressive it was actually NOT required for a working "deep-cooled" air-breathing rocket engine to have been developed and produced no later than the late 1960s with the knowledge and work done and available in the US aerospace community.

We missed it. We literally had ALL the data and because no one was looking for that specific outcome and WERE looking for one slightly different, (liquid air instead of deep cooled) everyone totally missed putting everything together into a viable system. And then SCramjets took over and...

Ok worse than THAT though is we had other equally promising systems that were bench/lab tested and ready for flight testing IF they had money or support and they simply shelved and forgotten because "priorities/missions/requirements" changed and they were no longer needed.

And this is a historically trended "outcome" for and with the United States in many matters. We tend to obsess over something and focus far more time, effort and resources into a single line of work only to look up and find out someone who didn't pursue the 'obvious' direction has managed to find a 'better' answer even if it isn't as "great" as the one we're looking for.

I'm frankly reminded of something Bill Murray said in "Stripes" heavily paraphrase and adapted but the US is really built on a large majority of people who were very full of themselves when they came here and they in turn have built up  huge reserve of hubris, exceptional-ism, and overconfidence that colors everything American's do. The annoying, (to some :) ) fact that we are in fact occasionally RIGHT being more exception than rule in no way helps either :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: momerathe on 10/07/2016 10:02 AM
I'm very disappointed in UK investors and the British Government for not investing more highly in REL. It's not surprising that REL are now looking towards the US and the US Military in particular as it's the only way they can get the funding to continue development. Like most of us on here, I'd rather see SABRE fully developed even if it has to go to the US to do it - though it really hurts that it can't be fully funded in the UK or Europe.

I agree with you on an emotional level, but we need to keep in mind the scale of the problem here.

IIRC REL estimated the development cost of Skylon to be of the same order as that of the A380. There's few entities worldwide capable of undertaking that, even fewer if you exclude the US (Previously I'd speculated the list was basically Airbus.. and that's it). The UK government was never going to bankroll it in this age of "austerity", and no investors are going to spaff billions of quid on such a speculative investment. And it's not just money - there's a huge amount of institutional know-how required.

Again, what I'm forced to come back to is this: we'll see a SABRE engine flying. Whether it's a TSTO concept, or a hypersonic bomber or whatever, that's a huge amount of risk reduction to any future programs.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Paul451 on 10/07/2016 06:02 PM
spaff billions of quid

Not sure it that violates the site's language policy or not.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: momerathe on 10/11/2016 01:26 PM
I admit nothing <_< .

Anyway, let me ask the thread a different question. REL have always put forth the idea that they are an engine company first and foremost. So, let's take them at their word: let's suppose than in 6-7 years time they've got a working 1/4 scale SABRE engine, that does everything they say it will, and anyone (export restrictions notwithstanding) can come along and buy one for their rocket.

What are the applications?

* TSTO first stage. Possibly using the cluster of engines mentioned in the Aviation Week article. Sound plausible - at least AFRL think it is. Who's going to build it? And will it be cost competitive?

* Space tourism. Assuming you think space tourism is a viable business model (I have my doubts), this seems like an easy target. A suborbital, RTLS, HTHL vehicle with decent crossrange has a load of safety and handling advantages. Having a proven, working engine is significant de-risking for potential investors.

* Military applications. Though I can't help thinking that this is more of an opportunity to milk the US Govt for development money.

Anything else? Smallsat launcher, perhaps?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 10/11/2016 04:59 PM

Anyway, let me ask the thread a different question. REL have always put forth the idea that they are an engine company first and foremost. So, let's take them at their word: let's suppose than in 6-7 years time they've got a working 1/4 scale SABRE engine, that does everything they say it will, and anyone (export restrictions notwithstanding) can come along and buy one for their rocket.

What are the applications?
If it's for sale then this would not be a 1/4 scale "model" it would be an actual SABRE engine with a design thrust 1/4 that of the planned unit for Skylon.

And since it's designed to run the whole runway-to-orbit mission how about building a SSTO HTO launcher around it?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: flymetothemoon on 10/12/2016 11:15 PM
I nearly made a similar comment myself John Smith. Why not just string a load of these units together and do a Skylon-like vehicle anyway? Maybe they would be alongside each other under a blended wing type belly? I don't know. Perhaps it would provide a reduction in complexity and make maintenance somewhat easier?  Anyway I decided against the comment since I figured there was a reason for the original '4 nozzle' design which I presume balances redundancy with efficiency etc. and using several of these single nozzle units presumably would result in more duplication of components. If so, might such duplication actually render the Skylon/SSTO concept less achievable - or certainly less payload?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: momerathe on 10/13/2016 09:42 AM
If it's for sale then this would not be a 1/4 scale "model" it would be an actual SABRE engine with a design thrust 1/4 that of the planned unit for Skylon.

That's what I meant. Apologies for clumsy phrasing.

Quote
And since it's designed to run the whole runway-to-orbit mission how about building a SSTO HTO launcher around it?

Sure. What size launcher, though? Like flymetothemoon suggests, you could cluster them up and build a full size skylon, but consider the following quote from the Aviation Week article:

Quote
Reaction CEO Mark Thomas believes the move to a smaller demonstrator is serendipitous. “It is now more affordable, more rapid to execute and will potentially find its first application quicker,

That implies to me that they're NOT thinking of a full-sized skylon as a first application.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Paul451 on 10/13/2016 09:00 PM
Just wanted to emphasise this quote:

(Via momerathe)
Quote
Reaction CEO Mark Thomas believes the move to a smaller demonstrator is serendipitous. “It is now more affordable, more rapid to execute and will potentially find its first application quicker..."

Cheaper, faster, easier to find the first paying client.

{sigh}

Can I remind everyone of the number of times this concept was raised by people on this thread (or its five predecessors) only to be shouted down by the small core of fanboys who insist that Skylon and SABRE can't be scaled down; that TSTO is stupid and wrong; that any interim development could only cost more money; that there's no possible advantage to any alternative to the path directly to Skylon and that anyone who says otherwise is merely ignorant.

After six longs threads, can we just stop with the shrill knee-jerk defence now? Can we accept that there are interim steps that are quicker, cheaper and easier than Skylon, and that REL is perfectly happily following that path? And not just "willing to do what the client wants, if the client is stupid enough to go in that stupid direction", but that it's actually better than a direct path.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: t43562 on 10/14/2016 05:11 AM
Just wanted to emphasise this quote:

(Via momerathe)
Quote
Reaction CEO Mark Thomas believes the move to a smaller demonstrator is serendipitous. “It is now more affordable, more rapid to execute and will potentially find its first application quicker..."

Cheaper, faster, easier to find the first paying client.

{sigh}

Can I remind everyone of the number of times this concept was raised by people on this thread (or its five predecessors) only to be shouted down by the small core of fanboys who insist that Skylon and SABRE can't be scaled down; that TSTO is stupid and wrong; that any interim development could only cost more money; that there's no possible advantage to any alternative to the path directly to Skylon and that anyone who says otherwise is merely ignorant.

After six longs threads, can we just stop with the shrill knee-jerk defence now? Can we accept that there are interim steps that are quicker, cheaper and easier than Skylon, and that REL is perfectly happily following that path? And not just "willing to do what the client wants, if the client is stupid enough to go in that stupid direction", but that it's actually better than a direct path.

No, I think not because it makes sense to go for the big plan and do it the most efficient way if you can.  What's happened thus far is the result of setbacks which we wish had not happened.   Should circumstances change for the better, I'm sure we will all be happy without the distracting side-shows.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Asteroza on 10/14/2016 07:08 AM
Considering the avoidance up to now of building 1/4 sub-Skylon sized SABRE engines due to the time/cost of designing the LH2 turbine, how much of system/weight penalty would you take by using multiple subscale LH2 turbines to feed a full scale SABRE?

Apparently there is a lot of duplicated components in a full scale SABRE, usually in groups of four, correct? Is it really as simple as saying use 4 subscale turbines and eat the weight increase in piping/manifolds?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 10/14/2016 01:35 PM
Considering the avoidance up to now of building 1/4 sub-Skylon sized SABRE engines due to the time/cost of designing the LH2 turbine, how much of system/weight penalty would you take by using multiple subscale LH2 turbines to feed a full scale SABRE?
Actually both the LOX and LH2 sides of the SABRE use 2 turbines.
Quote
Apparently there is a lot of duplicated components in a full scale SABRE, usually in groups of four, correct? Is it really as simple as saying use 4 subscale turbines and eat the weight increase in piping/manifolds?
No, parts are implemented as multiple sub units. The ramjets seems to use 4, but the pre-cooler operates as as single unit, while both LOX and LH2 turbines are a pair. OTOH IIRC the full size pre cooler uses 21 modules (which have already been tested).

So the question would be where do you draw the line?

The  reason REL have resisted a scaled down design was (according to Hempsell, when he posted on thread, that a scaled down LH2 turbopump at full chamber pressure would basically swallow a£350m budget without delivering a design you could use in the full size engine. So why bother?

However the SABRE 4 cycle appears to be able to de-couple the air breathing chamber pressure from the rocket chamber pressure much more, making the LH2 turbo pump more transferable to larger designs.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: knowles2 on 10/17/2016 03:26 AM
May be they are now just planning to buy a off the shelf LH2 turbopump, like the use on the Vulcain engine?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 10/17/2016 11:41 AM
May be they are now just planning to buy a off the shelf LH2 turbopump, like the use on the Vulcain engine?
There's no such thing as an OTS LH2 turbopump. 

Offhand I'd say the Vulcain TP is the wrong size and is powered by a gas generator burning O2/H2. SABRE uses a Helium loop. The blade design will be substantially different for a start because of the difference in properties between hot He and a mixture of hot GH2 and steam that Vulcains GG produces.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 10/17/2016 04:21 PM
May be they are now just planning to buy a off the shelf LH2 turbopump, like the use on the Vulcain engine?
There's no such thing as an OTS LH2 turbopump.

Yes there is and you in fact point out there are BUT point out they may need modification :)

Quote
Offhand I'd say the Vulcain TP is the wrong size and is powered by a gas generator burning O2/H2. SABRE uses a Helium loop. The blade design will be substantially different for a start because of the difference in properties between hot He and a mixture of hot GH2 and steam that Vulcains GG produces.

RL-10 maybe? I'm going to guess that dealing with hot helium will be at least a little easier to deal with than hot hydrogen and oxygen.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 10/19/2016 03:03 AM
Yes there is and you in fact point out there are BUT point out they may need modification :)
Fair point. I was in a hurry at the time. I should have said OTS if powered by a similar gas generator.  But by the time you've redesigned for the different drive gas you might as well have designed the whole thing from scratch and avoided having to be compatible with any existing parts.
Quote
RL-10 maybe? I'm going to guess that dealing with hot helium will be at least a little easier to deal with than hot hydrogen and oxygen.
I think REL are saying the new test engine will be about 40 Klb of thrust, so I think the RL10 TP is still a bit small. Wasn't the largest RL10 variant about 22-25 Klbs ?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Klebiano on 10/19/2016 04:11 AM
Yes there is and you in fact point out there are BUT point out they may need modification :)
Fair point. I was in a hurry at the time. I should have said OTS if powered by a similar gas generator.  But by the time you've redesigned for the different drive gas you might as well have designed the whole thing from scratch and avoided having to be compatible with any existing parts.
Quote
RL-10 maybe? I'm going to guess that dealing with hot helium will be at least a little easier to deal with than hot hydrogen and oxygen.
I think REL are saying the new test engine will be about 40 Klb of thrust, so I think the RL10 TP is still a bit small. Wasn't the largest RL10 variant about 22-25 Klbs ?

The Vinci engine, under development of Airbus Safran has the right specification. 40lbf.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: hkultala on 10/19/2016 06:25 AM
Yes there is and you in fact point out there are BUT point out they may need modification :)
Fair point. I was in a hurry at the time. I should have said OTS if powered by a similar gas generator.  But by the time you've redesigned for the different drive gas you might as well have designed the whole thing from scratch and avoided having to be compatible with any existing parts.
Quote
RL-10 maybe? I'm going to guess that dealing with hot helium will be at least a little easier to deal with than hot hydrogen and oxygen.
I think REL are saying the new test engine will be about 40 Klb of thrust, so I think the RL10 TP is still a bit small. Wasn't the largest RL10 variant about 22-25 Klbs ?

The Vinci engine, under development of Airbus Safran has the right specification. 40lbf.

There are many other things in "specification" than just size. Vinci is expander cycle, it's turbopumps are running on hot hydrogen warmed up in the nozzle. SABRE turmopump is running on hot helium.

He is about 2 times heavier than H2 which means the turbine should propably be quite different.

Also the output pressures might be totally different (but I don't know if they are)
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Katana on 10/24/2016 09:07 AM
2x heavier molecular weight could be balanced by differences of temperature and pressure.

Bigger problem: He gas compressor which is not included in standard turbopump units.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: t43562 on 10/29/2016 07:24 AM
This talk at the American Astronautical Society on reusability is a bit long but the bit from theman from DARPA at 1:49:29 is of interest, I think. where he says "rockets are fine, I don't need airbreathing"

http://livestream.com/accounts/563450/events/6533675/videos/140271208
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 10/29/2016 09:13 PM
This talk at the American Astronautical Society on reusability is a bit long but the bit from theman from DARPA at 1:49:29 is of interest, I think. where he says "rockets are fine, I don't need airbreathing"

http://livestream.com/accounts/563450/events/6533675/videos/140271208
The man from DARPA  is Jess Sponable, who ran the DC-X project and is running the XS-1 project.

The REL work is linked into the USARFRL

What's more interesting is he talked about a resin for composites usable up to 750 degrees. If that's degrees Celsius this is a major achievement. 750F (398c) would still be very impressive.

Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: t43562 on 11/03/2016 07:32 AM
This talk at the American Astronautical Society on reusability is a bit long but the bit from theman from DARPA at 1:49:29 is of interest, I think. where he says "rockets are fine, I don't need airbreathing"

http://livestream.com/accounts/563450/events/6533675/videos/140271208
The man from DARPA  is Jess Sponable, who ran the DC-X project and is running the XS-1 project.

The REL work is linked into the USARFRL

What's more interesting is he talked about a resin for composites usable up to 750 degrees. If that's degrees Celsius this is a major achievement. 750F (398c) would still be very impressive.

Indeed, I understand the difference between DARPA and the USAF but it is going to be interesting if XS-1 turns into a great success because then why pursue a risky and expensive new idea, having basically covered most of what you wanted with somewhat more conventional methods?  I mean what motivation would the USAF have for not "simply" going for XS-1 if it ends up being nearly what they need?   

He also made a specific point about not needing airbreathing and I though that  the idea must have been put to him and rejected.  That is not wonderful - he is saying that many other things are priorities first and if that's true for him, why not for everyone?

It is just interesting also in that video to see the attitude of the former Shuttle employees and current competitors to SpaceX. I may be oversensitive but I got the impression that anyone who proposes a different strategy is going to have difficulty proposing it to a crowd like that. They have so much experience and such a strong philosophy of how to do things and deal with uncertainty that they can't abandon them for the philosophy of the new kids.  I used to work for Nokia and their phones had to be usable in sub-zero temperatures with gloves (no capacitive touch screens)  and they had multi-day battery life and were tested to destruction quite extensively.  Almost all of these things seemed very important and they sort of are still but we all prioritised the large ram, screens and fast processors that directly clashed with the ideals of ruggedness and long life.  Most of us seem delighted with the result and would never go back.    So what I mean with this analogy is that very experienced people may be hostile to new ways of doing things and they can be completely right and yet still be missing the main point.

So I do wonder what reception SABRE will have when it is demonstrated.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/03/2016 11:38 AM
Indeed, I understand the difference between DARPA and the USAF but it is going to be interesting if XS-1 turns into a great success because then why pursue a risky and expensive new idea, having basically covered most of what you wanted with somewhat more conventional methods?  I mean what motivation would the USAF have for not "simply" going for XS-1 if it ends up being nearly what they need?   
XS-1 is a vehicle to get (eventually) to M10. Only the last of the test flights has to do this and that's nowhere near orbital velocity. AFAIK XS-1 is also an X plane. The next vehicle after it would be operational.

Either way you end up developing 2 stages.
Quote
He also made a specific point about not needing airbreathing and I though that  the idea must have been put to him and rejected.  That is not wonderful - he is saying that many other things are priorities first and if that's true for him, why not for everyone?
Part of the XS-1 baseline is that it needs an existing engine as the concept is viewed as high risk, low funding and short timescale. That means an OTS engine. There are not many of these but there are a few possible candidates.
Quote
So I do wonder what reception SABRE will have when it is demonstrated.
I'm not sure there's any point in worrying about wheather any particular audience will like SABRE or not.

If it meets it's performance goals then people will have to decide if they incorporate that into their plans.  SABRE gives you 2 things normal rockets don't.
1) Airbreathing Isp 6x greater than the highest rocket Isp. That pushes allowable structural mass fraction from 5% to more like 25% of GTOW, easing the design problem for the 2nd stage as well.
2)Air does not just stop carrying LOX it is 80% N2, so the reaction mass put out is actually 4x bigger than it would be if it was pure O2

I'll note you don't need a rocket  T/W to exceed the GTOW of the vehicle if the vehicle is winged so that's not an inherent advantage of SABRE but but the rockets higher T/W ratio is not a guaranteed win over SABRE once you factor in the mass of the LOX and its tankage and structure to carry it.

It would be interesting to find out what T/W a rocket engine would need to have to match SABRE in a HTOL design once the oxidzer mass and tank mass are taken into account.

Otherwise you have a choice.

a) Go VTOL and require your GTOT exceeds GTOW by about 25% regardless of how many stages you have  or
 b) Design a HTOL architecture of how many stages but with a structural mass fraction like a rocket rather than an aircraft, as the 2nd stage will have to be carried by the first.  This is relatively unknown territory.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: FutureSpaceTourist on 11/07/2016 06:55 AM
New FT article giving overview of Skylon and SABRE etc: https://www.ft.com/content/9b1244f6-78f7-11e6-97ae-647294649b28 (https://www.ft.com/content/9b1244f6-78f7-11e6-97ae-647294649b28)

Nothing new that I noticed. I suspect more a marketing piece, positioning Reaction Engines for the significant funding increase that'll be needed, eg

Quote
Mr Ford [Mark Ford head of ESA propulsion] estimates the total cost of eventually putting Sabre on to the wing of a vehicle at £500m-£1bn.

“We will need investment,” says Mr Thomas [RE CEO]. “This programme will get larger and the funds required will be exponentially larger.” He hopes the technology will interest partners from outside the space sector. Its cooling concept has applications well beyond aerospace, stretching to transport, power systems and aviation.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/07/2016 11:05 AM
New FT article giving overview of Skylon and SABRE etc: https://www.ft.com/content/9b1244f6-78f7-11e6-97ae-647294649b28 (https://www.ft.com/content/9b1244f6-78f7-11e6-97ae-647294649b28)

Nothing new that I noticed. I suspect more a marketing piece, positioning Reaction Engines for the significant funding increase that'll be needed, eg

Quote
Mr Ford [Mark Ford head of ESA propulsion] estimates the total cost of eventually putting Sabre on to the wing of a vehicle at £500m-£1bn.

“We will need investment,” says Mr Thomas [RE CEO]. “This programme will get larger and the funds required will be exponentially larger.” He hopes the technology will interest partners from outside the space sector. Its cooling concept has applications well beyond aerospace, stretching to transport, power systems and aviation.
Not a bad article, although nothing new on the technical side. It seems journalists still have trouble with the idea that SABRE does not separate O2 from air but burns all of it.

I do wish Mark Thomas had not used the word "exponential" when it came to discussing investment needs.  It's true REL has grown by orders of magnitude that's probably not a good word to use for future investors.  :(
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Matthew Ak43 on 11/07/2016 08:24 PM
The image enclosed is from a presentation that Richard Varvill gave at the British Interplanetary on July 22. (from a video on the BIS website, I thoroughly recommend joining) The new bits that I wasn't aware of is that the plan is that the test engine will be put into a flight test vehicle drone (as in the pic) with a small hydrogen tank, that he compared to the Lockheed D21 drone. The vehicle would exhilarate to about mach 5 for about 2 minutes until it has expended all its fuel then come in for a dead stick landing.

Richard said he had been told that the development of this test vehicle drone would cost about £1 billion.



Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Hanelyp on 11/07/2016 09:23 PM
It seems journalists still have trouble with the idea that SABRE does not separate O2 from air but burns all of it.
Given what would be involved in separating oxygen, you might as well use the nitrogen collected for something useful like reaction mass, at which point there's no point in separating out the oxygen.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Kansan52 on 11/07/2016 11:32 PM
The D21 was the first thing that came to mind seeing that picture of the test drone.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/07/2016 11:47 PM
The image enclosed is from a presentation that Richard Varvill gave at the British Interplanetary on July 22. (from a video on the BIS website, I thoroughly recommend joining) The new bits that I wasn't aware of is that the plan is that the test engine will be put into a flight test vehicle drone (as in the pic) with a small hydrogen tank, that he compared to the Lockheed D21 drone. The vehicle would exhilarate to about mach 5 for about 2 minutes until it has expended all its fuel then come in for a dead stick landing.

Richard said he had been told that the development of this test vehicle drone would cost about £1 billion.
I think you  mean accelerate  :)

This has been mentioned in outline before but it's good to get a bit more confirmation.  with only a single engine something like the D21 layout was always the probable design and the issue was the limited LH2 storage it would have.  This is very much an X plane. Ideally it will fly most of the early ascent profile, confirming the anticipated thrust/Isp Vs speed/altitude values and including the air breathing/rocket transition.

That said £1Bn sounds quite high for a vehicle with such limited endurance. While building an airframe able to go to cM5.6 is not simple the X15 (which was designed specifically to fly long enough for the whole airframe to reach a constant temperature) first flew in 1959. Eliminating  that requirement opens up a number of structural options, ranging from straight super alloys like the X15 to testing out the structural concepts for Skylon.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: knowles2 on 11/08/2016 12:00 AM
The image enclosed is from a presentation that Richard Varvill gave at the British Interplanetary on July 22. (from a video on the BIS website, I thoroughly recommend joining) The new bits that I wasn't aware of is that the plan is that the test engine will be put into a flight test vehicle drone (as in the pic) with a small hydrogen tank, that he compared to the Lockheed D21 drone. The vehicle would exhilarate to about mach 5 for about 2 minutes until it has expended all its fuel then come in for a dead stick landing.

Richard said he had been told that the development of this test vehicle drone would cost about £1 billion.
I think you  mean accelerate  :)

This has been mentioned in outline before but it's good to get a bit more confirmation.  with only a single engine something like the D21 layout was always the probable design and the issue was the limited LH2 storage it would have.  This is very much an X plane. Ideally it will fly most of the early ascent profile, confirming the anticipated thrust/Isp Vs speed/altitude values and including the air breathing/rocket transition.

That said £1Bn sounds quite high for a vehicle with such limited endurance. While building an airframe able to go to cM5.6 is not simple the X15 (which was designed specifically to fly long enough for the whole airframe to reach a constant temperature) first flew in 1959. Eliminating  that requirement opens up a number of structural options, ranging from straight super alloys like the X15 to testing out the structural concepts for Skylon.
I would have thought it make sense for them to test out as much as possible on the drone aircraft and eliminate as many of the hurdles as possible for large crafts that use this engine.


What about putting fuel pods under the wing of the drone to increase the fuel capacity? Could it also be done in a manner that would represent the nacelles on a full size craft?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/08/2016 07:01 AM
I would have thought it make sense for them to test out as much as possible on the drone aircraft and eliminate as many of the hurdles as possible for large crafts that use this engine.
Within reason yes. But again it's walking a line between retiring risk for a possible  vehicle structure and still leaving significant work for the airframe maker to be responsible for.  Yes I'd like them to prove out the SiC reinforced Titanium rod space frame with the SiC reinforced glass skin but if that multiplies the cost for this vehicle then going with something more conventional (super alloys, Titanium) would be the more sensible use of available funds. When in doubt, focus on the core task.

That said I think the water cooled brakes would be applicable to any concept and TBH I could see them having a market for commercial aircraft. A system that replaces possible a tonne of brakes that have to be carried with the aircraft with a water tank that can be emptied post takeoff could save an airline a lot of money over the life of an aircraft.
Quote

What about putting fuel pods under the wing of the drone to increase the fuel capacity? Could it also be done in a manner that would represent the nacelles on a full size craft?
The D21 design is fairly well known and I think quite a lot of its aerodynamics are either available for the real thing or have been simulated in various projects.  That means it's a low risk shape to build (provided the weight distribution mimics the original), although working out where to put the LH2 tanks is going to be tricky.  I'm guessing cylinders in the wings or along the body.

IIRC  REL estimate that it would only take about a cm of 60Kg/m^3 PU foam to keep the foam outer surface temp above the condensation point of water using sub cooled propellants.

Adding pods changes the aerodynamics, and in any case it's highly unlikely the drone would be scaled up to a full vehicle, which I think is likely to remain a 2 engine design.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/08/2016 08:29 AM
I'm not sure how much information has been released about this planned drone but we can make some deductions.

Can't remember if the ground engines thrust was given in lbs, Kgs or KN. I think it was lbs (which is odd for a UK company). If I'm wrong please divide by 2.2 for Kg  and multiply by 4.46 to give KN.

Based on the SpaceWorks USAFRL study they seem to think that thrust needed to be 60% of GTOW, rather than the usual 30% (IIRC the Ryan Firebee II supersonic drones had engine thrust 1/2 GTOW, suggesting 60% is conservative).

If the engine thrust is 40 000 lb that gives a GTOW of about 66 000lb. Assuming REL deliver an engine with proper T/W of 14:1 that's an engine of 2857 lb. Using the water cooled brakes concept gives a weight of less than 990 lb (that's 1.5% of GTOW but the historic rule of thumb relates brake weight to gross landing weight).

That leave 62153 lb for the whole structure, tankage and propellant (assuming you'll need LOX for a few seconds past the air breathing/rocket transition). My last data point is that most fluid tanks are 1% of the weight of the fluid they hold but LH2 tanks are somewhere between 2 and 10% of their fluid mass.

The challenge is can you build a vehicle to hold enough propellant to fly the full trajectory within this weight. Obviously if the idea that thrust has to be 60%of GTOW is reduced that gives you more mass to play with but AFAIK that's what the USAF study went with so probably best to trying fitting within that constraint first.

[EDIT. BTW it looks like the REL website is offline.  Does anyone know anything about this? ]
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: momerathe on 11/08/2016 08:38 AM
So in the third image, it mentions a constant inlet temp. of 400k. That implies it's the SABRE 4 cycle, right?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Mutley on 11/08/2016 09:22 AM
Quote
[EDIT. BTW it looks like the REL website is offline.  Does anyone know anything about this? ]

The website now says they are building a new site that will be up in mid November
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Star One on 11/08/2016 10:33 AM
Quote
[EDIT. BTW it looks like the REL website is offline.  Does anyone know anything about this? ]

The website now says they are building a new site that will be up in mid November

Perhaps we can expect some significant announcement then to coincide?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Baskii on 11/08/2016 12:12 PM
There are some interesting renders on the Reaction Engines Twitter feed (attached).
The first one shows the 'D21' test vehicle, a Skylon, and another twin-engined vehicle.  This vehicle is also shown in the second render.  It doesn't look like the AFRL TSTO concept - could it be an intermediate test vehicle?  Apologies if you've already covered this upthread and I missed it.
I note that one render shows it with straight engine nacelles, and the other with Skylon's curved nacelles.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Archibald on 11/08/2016 12:41 PM
The left model looks like a D-21 except with a different wing (the D-21 wing angled in the shape of a pear)

20 years ago NASA briefly investigated turning D-21 drones into RBCC test beds
https://www.google.fr/webhp?ie=utf-8&oe=utf-8&client=firefox-b&gfe_rd=cr&ei=1NUhWMepIoLDaNL2i6AK#q=%22D-21%22%22RBCC%22
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: hkultala on 11/08/2016 12:53 PM
There are some interesting renders on the Reaction Engines Twitter feed (attached).
The first one shows the 'D21' test vehicle, a Skylon, and another twin-engined vehicle.  This vehicle is also shown in the second render.  It doesn't look like the AFRL TSTO concept - could it be an intermediate test vehicle?  Apologies if you've already covered this upthread and I missed it.
I note that one render shows it with straight engine nacelles, and the other with Skylon's curved nacelles.

This is originally from some university research paper. They were studying an alternative aerodynamic configuration for skylon, and doing some CFD modeling  and comparing this to the official skylon configuration.

The paper was released something like one year ago.

Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Baskii on 11/08/2016 01:26 PM
There are some interesting renders on the Reaction Engines Twitter feed (attached).
The first one shows the 'D21' test vehicle, a Skylon, and another twin-engined vehicle.  This vehicle is also shown in the second render.  It doesn't look like the AFRL TSTO concept - could it be an intermediate test vehicle?  Apologies if you've already covered this upthread and I missed it.
I note that one render shows it with straight engine nacelles, and the other with Skylon's curved nacelles.

This is originally from some university research paper. They were studying an alternative aerodynamic configuration for skylon, and doing some CFD modeling  and comparing this to the official skylon configuration.

The paper was released something like one year ago.

Oh yes - I'd forgotten about that study.  Sorry...I guess I was getting overexcited...
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/08/2016 06:50 PM
So in the third image, it mentions a constant inlet temp. of 400k. That implies it's the SABRE 4 cycle, right?
Yes that compressor inlet temperature is about 127c, rather than the deeply pre cooled -150 to -200c, so SABRE 4.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Matthew Ak43 on 11/08/2016 07:48 PM
Richard Varville also confirmed that they are working with Sabre 4. Half the fuel consumption as you already probably know, but a much more heavier and  complex engine. I wonder if this would have been a much simpler and cheaper engine development process if they went with Sabre 3.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: dror on 11/08/2016 08:26 PM
From this simple diagram it looks like SABRE 4 should be able to work with different types of fuel such as LCH4, is that so?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Asteroza on 11/08/2016 10:20 PM
Drop tanks for takeoff->subsonic climb seems not unreasonable, after examining the zero start takeoff test envelope. Don't forget there are carrier planes available, such as StratoLaunch's Roc, and perhaps the Virgin Galactic SS2 carrier plane, which could do an air launch to reach other test envelopes.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/09/2016 07:52 AM
From this simple diagram it looks like SABRE 4 should be able to work with different types of fuel such as LCH4, is that so?
That depends. A compressor that can tolerate 127c inlet temp obviously needs less cooling. The question would be will you retain this in an operational vehicle? If not better to bite the bullet and go with LH2 from day one. The downside would be if you still want to go with SSTO you take a big hit on Isp. Air breathing is up to Mach 5.5. Orbital is more like M23. Air breathing can deliver several 1000 secs of Isp but I doubt it can make up for the loss in payload mass fraction that the lower Isp of LCH4. How important that is only REL know, although I'm sure they can (and have) modeled it.

Drop tanks for takeoff->subsonic climb seems not unreasonable, after examining the zero start takeoff test envelope.
AFAIK the only drop tank for cryogens was the Shuttle ET. Unless they were very low cost I think REL would prefer to get all the test flights done with a straight vehicle and avoid the complexity and expense, since they would be the only customer for this.
Quote
Don't forget there are carrier planes available, such as StratoLaunch's Roc, and perhaps the Virgin Galactic SS2 carrier plane, which could do an air launch to reach other test envelopes.
Is the Roc complete yet? AFAIK it's still being built, let alone had its first test flight.  White Knight 2 is flying but the problem with either is that they get  REL even further into the US ITAR rules minefield. 
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: hkultala on 11/09/2016 09:15 AM
From this simple diagram it looks like SABRE 4 should be able to work with different types of fuel such as LCH4, is that so?

1) It still needs quite cool fuel to be able to cool the air
2) All the pipe and pump sizes are calculated for H2.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: lkm on 11/10/2016 05:51 PM
There are some interesting renders on the Reaction Engines Twitter feed (attached).
The first one shows the 'D21' test vehicle, a Skylon, and another twin-engined vehicle.  This vehicle is also shown in the second render.  It doesn't look like the AFRL TSTO concept - could it be an intermediate test vehicle?  Apologies if you've already covered this upthread and I missed it.
I note that one render shows it with straight engine nacelles, and the other with Skylon's curved nacelles.

This is originally from some university research paper. They were studying an alternative aerodynamic configuration for skylon, and doing some CFD modeling  and comparing this to the official skylon configuration.

The paper was released something like one year ago.



I'm not so sure about that. They're similar to cfastt but not the same. Cfastt hasn't got winglets, and has a flat nose and curved trailing edges on the wings and the rear isn't totally flat on top.
To wild mass guess for a moment, to me it looks  like images from their projected test program and that along with the 'D21' they're thinking about a sub scale x-plane with 2 Ground Development to test the technology of the full scale Skylon and that the other image is perhaps the mythical Skylon E, the result of BAE aerodynamicists performing the same optimisations that resulted in cfastt and thus resulting in an aircraft that looks very similar, which would explain why the x plane resembles it.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/10/2016 10:46 PM

I'm not so sure about that. They're similar to cfastt but not the same. Cfastt hasn't got winglets, and has a flat nose and curved trailing edges on the wings and the rear isn't totally flat on top.
To wild mass guess for a moment, to me it looks  like images from their projected test program and that along with the 'D21' they're thinking about a sub scale x-plane with 2 Ground Development to test the technology of the full scale Skylon and that the other image is perhaps the mythical Skylon E, the result of BAE aerodynamicists performing the same optimisations that resulted in cfastt and thus resulting in an aircraft that looks very similar, which would explain why the x plane resembles it.
The "D21 like vehicle would be about the simplest configuration you could use if you only had one engine available. If you can afford a pair then you could go for something more Skylon like. The other fairly obvious option would be something resembling the V1

Moving engines to mid wing lowers the mass at the end of the cantilevers but probably complicates the airflow quite a lot. The SR71 essentially attached them to the upper portion of the engine housing, so servicing the engine meant you needed a building capable of holding the whole length of the wing and the engine cowling in the up position.

My feeling is that structural analysis is on firmer ground than airflow analysis so engines on wing tips is more structurally risky but less aerodynamically risky, and airflow is the one that's much less predictable.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: knowles2 on 11/12/2016 01:29 AM
May be we will be lucky and Reaction Engines new site will give us details of their plans and they plan to proceed over the next 5 years or so.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: adrianwyard on 11/12/2016 05:47 AM
I just noticed the temporary home page on REL's site includes a small graphic of a test vehicle, although what's depicted is different from the other D21-like ones elsewhere. It has wing-tip vertical stabilizers as opposed to one on the fuselage, and what could be an additional square inlet on top...
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/12/2016 09:44 AM
I just noticed the temporary home page on REL's site includes a small graphic of a test vehicle, although what's depicted is different from the other D21-like ones elsewhere. It has wing-tip vertical stabilizers as opposed to one on the fuselage, and what could be an additional square inlet on top...
You're right. the winglets are a departure from the D21 design although the wing layout looks pretty similar. Depending on the angle of the design that could be an additional inlet of some kind or an opening in the top surface. The classic reason for something like that would for an in flight refueling receptacle, which makes no sense. 

I note the full graphic shows Skylon on the left and the A2 design for the LAPCAT M5 hypersonic transport project on the right.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: lkm on 11/14/2016 11:58 AM
If we accept for the sake of argument that it is a sub scale x plane design using two GDE's then by simple scaling it should be able to put a couple of mt in orbit, and there does seem to be a small payload bay area on the render. So is there any utility to that beyond testing? Is anyone going to come along and say we'd like the small one please?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Rocket Science on 11/14/2016 12:37 PM
I just noticed the temporary home page on REL's site includes a small graphic of a test vehicle, although what's depicted is different from the other D21-like ones elsewhere. It has wing-tip vertical stabilizers as opposed to one on the fuselage, and what could be an additional square inlet on top...
I wonder if it is a ram intake to cool the outside of the engine bell and to use the hot expanded air to contribute to overall thrust...
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Ravenger on 11/14/2016 12:48 PM
It's a very interesting picture. The thing that confuses me is that the rectangular 'intake' feature doesn't make much sense given the streamlining of the vehicle.

I was wondering if what we're looking at is actually a wind tunnel or test model  (for air dropping or a rocket sled) and the strange feature on top is some sort of mount.  ???
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: dror on 11/14/2016 12:50 PM
If we accept for the sake of argument that it is a sub scale x plane design using two GDE's then by simple scaling it should be able to put a couple of mt in orbit, and there does seem to be a small payload bay area on the render. So is there any utility to that beyond testing? Is anyone going to come along and say we'd like the small one please?

I realy hope so.
Smaller payloads can use the advantages of a SSTO more intuitively than bigger ones.
A small skylon can take care of ISS ferry and resupply and deliver most of the LEO payloads. With on orbit refueling it can also deliver most of the SSO payloads.
But I remember reading here that they weren't interested in developing multiple vehicles, and that the guiding parameter was payload diameter, rather than mass.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/14/2016 02:11 PM
It's a very interesting picture. The thing that confuses me is that the rectangular 'intake' feature doesn't make much sense given the streamlining of the vehicle.

I was wondering if what we're looking at is actually a wind tunnel or test model  (for air dropping or a rocket sled) and the strange feature on top is some sort of mount.  ???
The mount is usually called a "stinger."  That's possible. It would depend what part of the model you specifically wanted information about as for aircraft they usually have the mount at that extreme rear.

If we accept for the sake of argument that it is a sub scale x plane design using two GDE's
GDE's?

Most speculation seems to have been around it being a launch bay for a 2nd or 2 stage LV to take small payloads (110Kg) to LEO.

Once you get away from full reusability operating costs rise considerably and you're in danger of being the maker/operator business model.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: lkm on 11/14/2016 11:32 PM


If we accept for the sake of argument that it is a sub scale x plane design using two GDE's
GDE's?

Most speculation seems to have been around it being a launch bay for a 2nd or 2 stage LV to take small payloads (110Kg) to LEO.

Once you get away from full reusability operating costs rise considerably and you're in danger of being the maker/operator business model.
GDE: Ground Development Engine which from the slide seems to be what they're calling a single propulsive unit SABRE, although given SABRE now seems to be able to consist of an arbitrary number of units behind an appropriately sized precooler and compressor I think they need a new naming scheme.

To my eyes the launch bay isn't really that big on the 'x plane', maybe a couple of metres long, is that big enough for any sort of existing  second stage and a payload ?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: oddbodd on 11/17/2016 01:11 AM
Looks like the new website is live... and it's... underwhelming.

A fairly generic site with pretty pictures, and most of the older interesting info gone so far as I can tell. More a brochure than an information site.

Also seems to me that focus has shifted toward hypersonic flight, with space access almost feeling like an "oh yeah, that too". It gets mentioned, but always secondary to hypersonic flight or mentions of how quickly you could fly from X to Y.

Is it just me, or is this picture (from the careers page) a little telling:
https://www.reactionengines.co.uk/wpcms/wp-content/uploads/2016/05/1607-REL-FIA2016-012_B-1-e1471338140911.jpg

Varville seemingly being pushed into the background, and no sign of Alan Bond. It's such a shame that we don't have a Brit version of Elon Musk. A bit of vision, some balls, and a honking big bag of cash. I'd love to be proved wrong, but it looks like the original vision is as dead as the proverbial parrot. Splattered over the windscreen by the relentless drive to justify ones existence on a per-quarterly clock.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: a_langwich on 11/17/2016 02:02 AM
Looks like the new website is live... and it's... underwhelming.

Isn't the lower vehicle in the header on this page
https://www.reactionengines.co.uk/vehicles/

a side view of the D-21-like vehicle mentioned above?  Or was that already known?
Title: The Reaction Engines Skylon Master Thread (6)
Post by: Star One on 11/17/2016 06:23 AM
Looks like the new website is live... and it's... underwhelming.

A fairly generic site with pretty pictures, and most of the older interesting info gone so far as I can tell. More a brochure than an information site.

Also seems to me that focus has shifted toward hypersonic flight, with space access almost feeling like an "oh yeah, that too". It gets mentioned, but always secondary to hypersonic flight or mentions of how quickly you could fly from X to Y.

Is it just me, or is this picture (from the careers page) a little telling:
https://www.reactionengines.co.uk/wpcms/wp-content/uploads/2016/05/1607-REL-FIA2016-012_B-1-e1471338140911.jpg

Varville seemingly being pushed into the background, and no sign of Alan Bond. It's such a shame that we don't have a Brit version of Elon Musk. A bit of vision, some balls, and a honking big bag of cash. I'd love to be proved wrong, but it looks like the original vision is as dead as the proverbial parrot. Splattered over the windscreen by the relentless drive to justify ones existence on a per-quarterly clock.

Or you empathise what you have at least a half realistic chance of getting financed and built in the short to medium term. Rather than complaining about the loss of something that probably didn't have a chance of becoming reality until at least the technology had actually proved itself in practical use.

There is also nothing in the new site that says that they've abandoned their longer term goals. Especially given on the vehicles page the first thing that's mentioned is space access, which hardly tallies with a downgrading of the importance of space.

I personally think the new site looks far more presentable and modern.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Mutley on 11/17/2016 08:01 AM
The part i found most interesting was on this page:
https://www.reactionengines.co.uk/sabre/#6 (https://www.reactionengines.co.uk/sabre/#6)

"There are three core building blocks to the SABRE engine, the pre-cooler, the engine core and the rocket system. We plan to demonstrate each of these independently at flight scale in 2017, 2018 and 2019 respectively.

We’re about to start building a significant new UK test site to test critical subsystems and aim to test a fully integrated engine in 2020."
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Alpha_Centauri on 11/17/2016 09:55 AM
Looks like the new website is live... and it's... underwhelming.

Isn't the lower vehicle in the header on this page
https://www.reactionengines.co.uk/vehicles/

a side view of the D-21-like vehicle mentioned above?  Or was that already known?

Yes that's new. Hard to tell but it looks like the possible intake mentioned previously is some kind of auxiliary jet. Can't fathom why though.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/17/2016 10:06 AM
This is the 3rd generation of the REL website. It's certainly the most polished and about the least informative, if you're aware of the previous versions in terms of what their background work has been.  All the PDF's are gone AFAIK.

Pulled up the SABRE page, tried to scroll down.Needed to allow "typekit" before it would let me. I'm wondering if the site was tested by someone on the laptop they wrote it on instead from another browser outside their network.  :(

I think the most interesting thing about this page is their plan to test the precooler, engine core and rocket system in 2017/18/19 at flight scale, with the goal of a flight vehicle in 2020.

Note they did not say full trajectory, IE to LEO, so I doubt this will be an SSTO, but even a few seconds past the rocket transition (in a flight vehicle) would retire a lot of risk.

Possibly the most interesting stuff was a couple of press releases. In July this year they were part of a consortium headed by "Orbital Access Ltd" looking at small space launchers for the UK. Interestingly this was specifically in regard to HTO and included SSTL and both Strathclyde and Glasgow universities. They are based at Prestwick airport.

That said their website shows something quite a lot like an Orbital-ATK Pegasus.

Another item dates from 2015 when REL announced they had been working with the Defense Science Technology Laboratory of the MoD since 2013 on military applications of SABRE.

IIRC that pre dates their work with the USAFRL.

The new website is a bit more outward looking and REL looking to be trying to capitalize on the skills and IP they've generated over the last thirty years to be more self funding in pursuing their goals.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/17/2016 10:36 AM
Looks like the new website is live... and it's... underwhelming.

Isn't the lower vehicle in the header on this page
https://www.reactionengines.co.uk/vehicles/

a side view of the D-21-like vehicle mentioned above?  Or was that already known?
You're right. It is new. On the "placeholder" page you appeared to be looking down from the front onto the vehicle. I thought it could be in flight refueling receptacle, but that made no sense. There are no known LH2 flight refueling tankers anywhere in the world.

From the side it's obviously a separate fairing. It's possible it could be housing an auxiliary engine for return to base when it finishes its test flight but this is not as sensible as it seems. If this will be a sub scale SABRE presumably it will have close to SABRE 4 T/W IE 14:1. No jet is that good. It would make more sense to glide back with the main intake closed (to limit LH2 use) to a low enough speed then restart the SABRE briefly. Remember SABRE in air breathing has the Isp of a jet, not a rocket.  The features that made this a good idea for Shuttle don't really apply.

So what is it. Some sort of payload bay? Maybe. What it reminds me quite strongly of is the XCOR plan for the Lynx spaceplane.  While part of their business plan was near space joy rides for wealthy tourists they were also looking at the small sat launch market. Their plan was the pilot would fly solo, with a small rocket in a dorsal pod, to protect it from the worst of the reentry heating. Once high and fast enough they would put the Lynx into an appropriate attitude, open it and fire the rocket. Since this was in place of a passenger the whole package was planned as a separate unit to be mounted, and de-mounted as needed.

We know REL were looking to do a liquid fueled sounding rocket to simulate air breathing performance using IIRC LOX/Ammonia/GN2 to get the right gas properties. How big a payload would depend on what the flight vehicles performance was. SSTL satellites are in the 70cm cube, 100Kg range IE well above cubesats.

It's also interesting the head of their US office came from the LM branch that deals with "Responsive Space." That's the US military term for short notice, fast turnaround launches to increase, or replace space assets to carry out a particular task.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: t43562 on 11/17/2016 01:03 PM
From the side it's obviously a separate fairing. It's possible it could be housing an auxiliary engine for return to base when it finishes its test flight but this is not as sensible as it seems. If this will be a sub scale SABRE presumably it will have close to SABRE 4 T/W IE 14:1. No jet is that good. It would make more sense to glide back with the main intake closed (to limit LH2 use) to a low enough speed then restart the SABRE briefly. Remember SABRE in air breathing has the Isp of a jet, not a rocket.  The features that made this a good idea for Shuttle don't really apply.

Could it be . . . .da da da daaaaaa . . . a scramjet? :-D
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Star One on 11/17/2016 03:21 PM
This is the 3rd generation of the REL website. It's certainly the most polished and about the least informative, if you're aware of the previous versions in terms of what their background work has been.  All the PDF's are gone AFAIK.

Pulled up the SABRE page, tried to scroll down.Needed to allow "typekit" before it would let me. I'm wondering if the site was tested by someone on the laptop they wrote it on instead from another browser outside their network.  :(

I think the most interesting thing about this page is their plan to test the precooler, engine core and rocket system in 2017/18/19 at flight scale, with the goal of a flight vehicle in 2020.

Note they did not say full trajectory, IE to LEO, so I doubt this will be an SSTO, but even a few seconds past the rocket transition (in a flight vehicle) would retire a lot of risk.

Possibly the most interesting stuff was a couple of press releases. In July this year they were part of a consortium headed by "Orbital Access Ltd" looking at small space launchers for the UK. Interestingly this was specifically in regard to HTO and included SSTL and both Strathclyde and Glasgow universities. They are based at Prestwick airport.

That said their website shows something quite a lot like an Orbital-ATK Pegasus.

Another item dates from 2015 when REL announced they had been working with the Defense Science Technology Laboratory of the MoD since 2013 on military applications of SABRE.

IIRC that pre dates their work with the USAFRL.

The new website is a bit more outward looking and REL looking to be trying to capitalize on the skills and IP they've generated over the last thirty years to be more self funding in pursuing their goals.

It worked fine on my mobile which I imagine was what it was first and foremost designed to work on judging by the overall design.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: adrianwyard on 11/17/2016 04:38 PM
From the side it's obviously a separate fairing. It's possible it could be housing an auxiliary engine for return to base when it finishes its test flight but this is not as sensible as it seems. If this will be a sub scale SABRE presumably it will have close to SABRE 4 T/W IE 14:1. No jet is that good. It would make more sense to glide back with the main intake closed (to limit LH2 use) to a low enough speed then restart the SABRE briefly. Remember SABRE in air breathing has the Isp of a jet, not a rocket.  The features that made this a good idea for Shuttle don't really apply.

Could it be . . . .da da da daaaaaa . . . a scramjet? :-D

How ironic would that be! And yet, it's as good a theory as any yet floated. Assuming the vehicle hits the intended Mach numbers it would be an excellent test bed for scramjet testing - and one that returns them safely rather than ditching them X-43 style.

If this turns out to be correct, then the logic behind it will have been something like this:

Location: somewhere in the USAF.

"So you're saying this REL project can be used to test our scramjets?"
"Yes, sir."
"And your confident it will actually fly at the hypersonic speeds we wish to test at?"
"Yes, sir. It checks out."
"Then that's all I need to know: here's your check. I really hope this test bed will finally allow us to prove the value of scramjets at that flight speed. I hear rumors of a competing technology from the UK that we need to beat to the punch, so get to it!"

I'm mostly joking of course as there are cases where scramjet technology would be more suitable than SABRE.

Another slim possibility is the features on top are there to test the bypass ramjets intended for the full size SABRE?



Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Ravenger on 11/17/2016 05:19 PM
You can view the entire vehicle background image, which has a full view of the proposed UAV:

https://www.reactionengines.co.uk/wpcms/wp-content/uploads/2016/11/Skylon_LApcat_UAV_Side-1.jpg

It really looks like there's some form of secondary engine mounted on top of the airframe.

As adrianwyard says it could be a bypass burner test feature.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Alpha_Centauri on 11/17/2016 05:45 PM
Might sound mad but honestly it looks a bit like a pulsejet.  These are fuel hungry and comparatively simple/lightweight, so actually makes some sense as a bypass alternative.  But they are not generally supersonic.

Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/17/2016 07:38 PM

I'm mostly joking of course as there are cases where scramjet technology would be more suitable than SABRE.
That's certainly an imaginative idea. It would depend on the design of the airframe since it's already known that SCramjets can run up to M9 and have very poor T/W ratios. IOW that "backup" or supplementary system would be 1/2 the GTOW of the vehicle.

SCRamjets only make sense if you need long duration + high altitude + high speed (>M5 as conventional ramjets have operated to that speed already) and you're OK with high airframe heating and very poor T/W since you'll still need another system to get it up operating speed. About the only potential benefit they have is they can run with room temperature storable fuels. Basically unless you can find a way to make them accelerate from a standing start and improve the abysmal T/W ratio this is only ever going to be a missile technology.
Quote
Another slim possibility is the features on top are there to test the bypass ramjets intended for the full size SABRE?
If the test vehicle is a complete SABRE it will have a spill ramjet of some kind on it already.
Title: The Reaction Engines Skylon Master Thread (6)
Post by: Star One on 11/17/2016 08:19 PM
Perhaps they are going to use it to test the proposed hybrid propulsion system for the SR-72.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Robotbeat on 11/17/2016 10:44 PM
This new plan is way better. May actually happen!
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Alpha_Centauri on 11/18/2016 12:23 PM
Post in commercial about REL/BAE partner operator Orbital Access raising funds;

http://forum.nasaspaceflight.com/index.php?topic=41650.msg1610740#new


Also don't suppose there's a remote chance anyone here has access to this full paper by Orbital Access' CEO? It's essentially talking about the next steps using a SABRE-derived small launcher/testbed.

The abstract gives some hints;

http://eprints.gla.ac.uk/130443/
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: topsphere on 11/18/2016 02:44 PM
Post in commercial about REL/BAE partner operator Orbital Access raising funds;

http://forum.nasaspaceflight.com/index.php?topic=41650.msg1610740#new


Also don't suppose there's a remote chance anyone here has access to this full paper by Orbital Access' CEO? It's essentially talking about the next steps using a SABRE-derived small launcher/testbed.

The abstract gives some hints;

http://eprints.gla.ac.uk/130443/

Attached
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: oddbodd on 11/18/2016 04:41 PM
Looks like the new website is live... and it's... underwhelming.

A fairly generic site with pretty pictures, and most of the older interesting info gone so far as I can tell. More a brochure than an information site.

Also seems to me that focus has shifted toward hypersonic flight, with space access almost feeling like an "oh yeah, that too". It gets mentioned, but always secondary to hypersonic flight or mentions of how quickly you could fly from X to Y.

Is it just me, or is this picture (from the careers page) a little telling:
https://www.reactionengines.co.uk/wpcms/wp-content/uploads/2016/05/1607-REL-FIA2016-012_B-1-e1471338140911.jpg

Varville seemingly being pushed into the background, and no sign of Alan Bond. It's such a shame that we don't have a Brit version of Elon Musk. A bit of vision, some balls, and a honking big bag of cash. I'd love to be proved wrong, but it looks like the original vision is as dead as the proverbial parrot. Splattered over the windscreen by the relentless drive to justify ones existence on a per-quarterly clock.

Or you empathise what you have at least a half realistic chance of getting financed and built in the short to medium term. Rather than complaining about the loss of something that probably didn't have a chance of becoming reality until at least the technology had actually proved itself in practical use.

There is also nothing in the new site that says that they've abandoned their longer term goals. Especially given on the vehicles page the first thing that's mentioned is space access, which hardly tallies with a downgrading of the importance of space.

I personally think the new site looks far more presentable and modern.

The issue as I see it is that the original Skylon SSTO concept had a narrow(-ish) window of opportunity. It made sense while rockets were expendable, but we now have Space X pushing the envelope on reusability, and if they reduce costs enough (not necessarily down to theoretical Skylon levels) then the business case for progressing to create Skylon (or similar) will not be attractive enough to pull in the needed investment. This new site seems to push SSTO Skylon further and further out, giving the likes of Space X more and more time to consolidate and lock down the market. So SSTO Skylon is at risk of withering on the vine, and without it (or something similar) it's not clear that we will ever reach SSTO and airliner style operations. Without those two things space access is never going to progress much beyond what we already have. Here's an illustration https://en.wikipedia.org/wiki/Timeline_of_spaceflight
The annual launch rate is not increasing even with commercial competition, not even breaking a hundred since 1990, and the failure rate is not being significantly reduced.
In comparison Heathrow handles 1400 takeoffs and landings in one day, with an almost non-existent failure rate. And that's why airline ops and SSTO are needed. Yes, yes, I know the whole mantra that space is hard, but unless we do something better than rockets which have been the modus operandi since the 60's, we as a species are likely to be permanently stuck on this rock until whatever ELE comes along to wipe us out.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Hanelyp on 11/18/2016 05:34 PM
Skylon SSTO vs. rocket 2STO seems to me to depend on how much attention the Sabre engine needs between flights vs. stage re-mating.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: TrevorMonty on 11/18/2016 05:52 PM
Not very clear but this is how I interpret it.

The plan is to develop an RP1/LOX powered air launched booster similar to XS1. Payload to SSO would be 500kg, with upper stage stored in payload bay. A modified version of booster airframe would also be used to test SABRE.

All going well with SABRE tests, they would build commercial TSTO version powered by SABRE, still going after same payload range ie smallsats to SSO.

If SABRE engine doesn't work out they still have RP1/LOX RLV.

Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Hanelyp on 11/18/2016 06:10 PM
Sabre is conceived as a zero to ~Mach 5 air breathing engine, then transitioning to rocket mode.  Why would the test vehicle need to be launched at speed/altitude?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Alpha_Centauri on 11/18/2016 06:43 PM
Sabre is conceived as a zero to ~Mach 5 air breathing engine, then transitioning to rocket mode.  Why would the test vehicle need to be launched at speed/altitude?

Look at the test vehicle, does it look like it has much room for LH2 fuel tanks?

The most crucial parts of the launch phase they will need to test in-flight are the hypersonic phase and the cycle transition from airbreathing to rocket mode. Air-launching allows you to build a far simpler test vehicle to reach these regimes.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/18/2016 06:57 PM
Post in commercial about REL/BAE partner operator Orbital Access raising funds;

http://forum.nasaspaceflight.com/index.php?topic=41650.msg1610740#new


Also don't suppose there's a remote chance anyone here has access to this full paper by Orbital Access' CEO? It's essentially talking about the next steps using a SABRE-derived small launcher/testbed.

The abstract gives some hints;

http://eprints.gla.ac.uk/130443/

Attached
Thanks for that. It's made interesting reading.

Looking over the plan it's basically a semi reusable Pegasus XL. In fact I think if you convert the price to $/lb it's also about the same price. IE the most expensive LV on the planet.

That said it is reusable and being LOX/RP1 should have substantially higher performance, giving a smaller package. IIRC OSC launch price doubled when their core supplier (who IIRC was also one of their owners) doubled their solid rocket prices. Going with conformal IE wet wings should give a narrower fuselage and potentially better aerodynamics.

For real cost savings you'd want to make the upper stage as "dumb" as possible. I'm wondering if you could do it all in hard wired logic in a FPLA or similar. A return to the Black Arrow approach?

The real question is where it fits in with REL's plans?

The last graphic shows a progression from the D21 like single engine UAV to something else then (presumably) a full size Skylon.

I'm vague where exactly the OA vehicle sits in this. Do they plan to upgrade it to wing mounted engines? Put a sub scale SABRE in the payload bay? If so what is it testing? The "D21" should have tested past the AB/rocket transition already. Is it big enough to demonstrate LH2 rocket to orbit? Will it return?

It would at least appear that a UK smallsat launcher is possible. The question is how much of the market can it capture and how much will it cost to develop.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Alpha_Centauri on 11/18/2016 07:00 PM
Attached

Thanks, not quite as much detail on the vehicle as i'd hoped but it does give a good idea of what is going on in the  background and show the evolution from this to the flight test vehicle cgi.

Not very clear but this is how I interpret it.

The plan is to develop an RP1/LOX powered air launched booster similar to XS1. Payload to SSO would be 500kg, with upper stage stored in payload bay. A modified version of booster airframe would also be used to test SABRE.

All going well with SABRE tests, they would build commercial TSTO version powered by SABRE, still going after same payload range ie smallsats to SSO.

If SABRE engine doesn't work out they still have RP1/LOX RLV.

Yes that's how I see it.  The reality is flight-testing SABRE is going to cost a lot.  BAE are already working with Orbital Access to study modifiying the carrier aircraft for its Orbital 500 plan.  It makes sense to synergise their efforts and allow the test vehicle to provide a return, making it easier to sell to investors.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Alpha_Centauri on 11/18/2016 07:11 PM
The "D21" should have tested past the AB/rocket transition already. Is it big enough to demonstrate LH2 rocket to orbit? Will it return?

The configuration 3B-1 in figure 5 is the D21 vehicle. 3A-2 is an earlier configuration. The concept design work was done by BAE...
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 11/18/2016 07:16 PM
The issue as I see it is that the original Skylon SSTO concept had a narrow(-ish) window of opportunity. It made sense while rockets were expendable, but we now have Space X pushing the envelope on reusability, and if they reduce costs enough (not necessarily down to theoretical Skylon levels) then the business case for progressing to create Skylon (or similar) will not be attractive enough to pull in the needed investment. This new site seems to push SSTO Skylon further and further out, giving the likes of Space X more and more time to consolidate and lock down the market. So SSTO Skylon is at risk of withering on the vine, and without it (or something similar) it's not clear that we will ever reach SSTO and airliner style operations. Without those two things space access is never going to progress much beyond what we already have. Here's an illustration https://en.wikipedia.org/wiki/Timeline_of_spaceflight
The annual launch rate is not increasing even with commercial competition, not even breaking a hundred since 1990, and the failure rate is not being significantly reduced.
In comparison Heathrow handles 1400 takeoffs and landings in one day, with an almost non-existent failure rate. And that's why airline ops and SSTO are needed. Yes, yes, I know the whole mantra that space is hard, but unless we do something better than rockets which have been the modus operandi since the 60's, we as a species are likely to be permanently stuck on this rock until whatever ELE comes along to wipe us out.

Oddbodd; Even with Skylon and SSTO launch will not be anything like 'airline' operations. The analogies break down very quickly beyond a very basic application. Space launch is very different than any other form of transportation used on Earth, it has to be as it has almost no way to 'tap' into the pre-existing nodes and networks of Earth based transportation and has strictly limited destinations and current uses.

Launching something into space, even assuming an 'operational' (Skylon for example) SSTO is not only difficult it requires deliver of the 'payload' to a specific orbit when all is said and done and unlike any Earthly transportation the main vehicle has to provide all aspects of that delivery since in most cases the payload can not. Our notional vehicle requires something to the size of, but far more complex and expensive to build and maintain, a 747 which then 'delivers' a payload equivalent of a DC3. (Not the whole aircraft, JUST its cargo and/or passenger equivalent)

Heathrow didn't exist 100 years ago but London did and it 'handled' quite a lot more cargo and passengers than Heathrow does on a daily basis back then. And anyone looking to compare the rickety, wobbly 'aeroplane' to what ships could accomplish was laughed at. But the aeroplane could in fact eventually interface with the same destinations that the ships did and while they could not carry MORE cargo/passengers per trip they did so faster and therefore could make more trips over the same amount of time.

Space launch has no destinations already in place and only a very limited economic 'niche' to service so even if they WERE capable of being operated at 'aircraft' rates and utility they would not have the market to do so. Having relatively 'cheaper' and more ready access will increase that market... Somewhat but in truth the overall 'current' market will quickly become saturated. The hope is that increased access will generate new markets and forces but in truth that's not how it's ever worked before as there always been pre-existing destinations and markets which new and more 'efficient' transportation systems tapped into to expand and grow.

There are no destinations, no pre-existing markets or service sectors to expand into other than the few that exist today and very little likelihood of those markets expanding significantly due to greater access and lower cost. (There is or course SOME elasticity in the pre-existing markets but there are regulatory and governmental/international pressures that will be applied to keep those from expanding too rapidly)

In summery, (too late I know :) ) the question has always been less about capability and access but economics, market and requirements. Space travel has always been significantly harder than air travel and it may be reduced some with coming technology and operations but it will not ever be as easy as air travel, or ships, trains, or cars, trucks, etc unless there is a VERY radical change in the fundamental aspects of space travel. SSTO, air-breathing or not, is not that radical of a change despite what many people think.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Paul Howard on 11/18/2016 08:08 PM
I like how they've improved their website. Says they are serious about keeping up to date.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Robotbeat on 11/18/2016 08:17 PM
Also, I have to say the idea of a civil hypersonic transport is super exciting to me, too. And it'd use hydrogen, so technically this can be done pretty easily with zero carbon emissions! Very neat. :)
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: oddbodd on 11/19/2016 03:38 AM
The issue as I see it is that the original Skylon SSTO concept had a narrow(-ish) window of opportunity. It made sense while rockets were expendable, but we now have Space X pushing the envelope on reusability, and if they reduce costs enough (not necessarily down to theoretical Skylon levels) then the business case for progressing to create Skylon (or similar) will not be attractive enough to pull in the needed investment. This new site seems to push SSTO Skylon further and further out, giving the likes of Space X more and more time to consolidate and lock down the market. So SSTO Skylon is at risk of withering on the vine, and without it (or something similar) it's not clear that we will ever reach SSTO and airliner style operations. Without those two things space access is never going to progress much beyond what we already have. Here's an illustration https://en.wikipedia.org/wiki/Timeline_of_spaceflight
The annual launch rate is not increasing even with commercial competition, not even breaking a hundred since 1990, and the failure rate is not being significantly reduced.
In comparison Heathrow handles 1400 takeoffs and landings in one day, with an almost non-existent failure rate. And that's why airline ops and SSTO are needed. Yes, yes, I know the whole mantra that space is hard, but unless we do something better than rockets which have been the modus operandi since the 60's, we as a species are likely to be permanently stuck on this rock until whatever ELE comes along to wipe us out.

Oddbodd; Even with Skylon and SSTO launch will not be anything like 'airline' operations. The analogies break down very quickly beyond a very basic application. Space launch is very different than any other form of transportation used on Earth, it has to be as it has almost no way to 'tap' into the pre-existing nodes and networks of Earth based transportation and has strictly limited destinations and current uses.

Launching something into space, even assuming an 'operational' (Skylon for example) SSTO is not only difficult it requires deliver of the 'payload' to a specific orbit when all is said and done and unlike any Earthly transportation the main vehicle has to provide all aspects of that delivery since in most cases the payload can not. Our notional vehicle requires something to the size of, but far more complex and expensive to build and maintain, a 747 which then 'delivers' a payload equivalent of a DC3. (Not the whole aircraft, JUST its cargo and/or passenger equivalent)

Heathrow didn't exist 100 years ago but London did and it 'handled' quite a lot more cargo and passengers than Heathrow does on a daily basis back then. And anyone looking to compare the rickety, wobbly 'aeroplane' to what ships could accomplish was laughed at. But the aeroplane could in fact eventually interface with the same destinations that the ships did and while they could not carry MORE cargo/passengers per trip they did so faster and therefore could make more trips over the same amount of time.

Space launch has no destinations already in place and only a very limited economic 'niche' to service so even if they WERE capable of being operated at 'aircraft' rates and utility they would not have the market to do so. Having relatively 'cheaper' and more ready access will increase that market... Somewhat but in truth the overall 'current' market will quickly become saturated. The hope is that increased access will generate new markets and forces but in truth that's not how it's ever worked before as there always been pre-existing destinations and markets which new and more 'efficient' transportation systems tapped into to expand and grow.

There are no destinations, no pre-existing markets or service sectors to expand into other than the few that exist today and very little likelihood of those markets expanding significantly due to greater access and lower cost. (There is or course SOME elasticity in the pre-existing markets but there are regulatory and governmental/international pressures that will be applied to keep those from expanding too rapidly)

In summery, (too late I know :) ) the question has always been less about capability and access but economics, market and requirements. Space travel has always been significantly harder than air travel and it may be reduced some with coming technology and operations but it will not ever be as easy as air travel, or ships, trains, or cars, trucks, etc unless there is a VERY radical change in the fundamental aspects of space travel. SSTO, air-breathing or not, is not that radical of a change despite what many people think.

Randy

I understand what you're saying, and agree with much. What I'm trying to say (in a cack-handed way) is that the current methods are too slow, inflexible and prone to exploding to ever end up with a significant human space presence. Even Space X with a partially reusable rocket will take weeks (if not months) to reintegrate for a second launch.

It's a vicious circle: no destinations, no market; no market, no demand; no demand, no destinations. Until someone/something comes along to break that, it feels like we will be forever stuck in LEO for manned missions, GEO for communications, and the occasional splurge for scientific robotic observation BEO. So those of us dreaming of Moon/Mars colonies, orbital space stations, or research bases on Europa, will just keep on dreaming.

The only way we get space based destinations (and thus markets and demand) is if we make them, and they aren't realistically going to be created using expendable rockets. Look at the ISS; constructed over 16 years from payloads launched on EELV's and the partially reusable jigsaw puzzle that was the STS. It is totally dependent on a steady stream of additional launched supplies from earth (excl. energy), holds a handful of people in non-ideal conditions, cost $150 billion, and can't (or doesn't as far as I know) act as a staging point for beyond earth orbit missions.

I'm not saying we need to reach airline levels of ops or flight rate. That would be insane. But till the turnaround can be brought down to say sub-week and not tying up the launchpad/runway, we will never go beyond the current levels of activity. I just don't think you can push out further with any vehicle that you have to reassemble/replace every time you use it. Are there any other fully reusable SSTO's in active development right now? Skylon was the only one I'm aware of, and is now firmly on the back burner in favour of military and industrial applications, hypersonic planes, and if we're lucky a small satellite launcher. With all those diversions it would likely be the 30's before serious attention/finances would be brought to bear on a Skylon scale SSTO if it ever happens. By this time will the reduced benefits still justify the investment? To quote Hudson: "Game over, man. Game over!"
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: oddbodd on 11/19/2016 03:52 AM
Also, I have to say the idea of a civil hypersonic transport is super exciting to me, too. And it'd use hydrogen, so technically this can be done pretty easily with zero carbon emissions! Very neat. :)

You do realize that the vast majority (~95%) of hydrogen comes from the processing of fossil fuels? Electrolysis (i.e. using wind, hydro or solar PV) is highly inefficient. There are laboratory scale experiments that may eventually bear fruit (i.e. algae), but I certainly wouldn't say that currently hydrogen can be done pretty easily with zero carbon emissions.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: t43562 on 11/19/2016 05:21 AM
I'm not saying we need to reach airline levels of ops or flight rate. That would be insane. But till the turnaround can be brought down to say sub-week and not tying up the launchpad/runway, we will never go beyond the current levels of activity. I just don't think you can push out further with any vehicle that you have to reassemble/replace every time you use it. Are there any other fully reusable SSTO's in active development right now? Skylon was the only one I'm aware of, and is now firmly on the back burner in favour of military and industrial applications, hypersonic planes, and if we're lucky a small satellite launcher. With all those diversions it would likely be the 30's before serious attention/finances would be brought to bear on a Skylon scale SSTO if it ever happens. By this time will the reduced benefits still justify the investment? To quote Hudson: "Game over, man. Game over!"

The investment will also be greatly reduced as a consequence of all the diversions. Meanwhile we should be looking for new applications which are going to make investment flow in. We probably only need so much global-positioning and internet-from-space so what's going to be next that will unlock all the piggy banks?   No point burping out a Skylon in one great effort and then watching the company go bust while it waits for the ideas to catch up.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/19/2016 09:41 AM
The investment will also be greatly reduced as a consequence of all the diversions.
That's certainly the hope but the fact remains that Skylon is very large. The question is how much of that cost is down to it's novelty and how much is down to it's size. Remember these are the cost models that said SX's spend on the F1 up to the first F9 launch could not be less than $2Bn, which was simply not the case. On that basis, the SABRESkylon programme, run as efficiently as SX's development, would actually be about $2Bn.  [EDIT IRL there are enough "unknown unknowns" to make that doubtful. But how doubtful is a question you can only really answer after you'd run the project  :( . I'd bet REL's internal estimates, based on what's actually been done and how much it's actually cost are rather different, but you can't take those to a bank. ]
Quote
Meanwhile we should be looking for new applications which are going to make investment flow in. We probably only need so much global-positioning and internet-from-space so what's going to be next that will unlock all the piggy banks?   No point burping out a Skylon in one great effort and then watching the company go bust while it waits for the ideas to catch up.
Skylon, rather than SABRE also changes the business model from a sole builder /sole operator model to a sole builder multiple operators model. As Skylon should be able to self-ferry it also means it can stay in one country and only fly to an equatorial launch site for full load missions. Depending on latitude it could spend most of its career being launched from its home country.

That level of flexibility is simply impossible for any kind of rocket that's wedded to a unique launch pad configuration.  The closest this has been approached is the Soyuz and that's still months between launches.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: knowles2 on 11/19/2016 08:28 PM
Sabre is conceived as a zero to ~Mach 5 air breathing engine, then transitioning to rocket mode.  Why would the test vehicle need to be launched at speed/altitude?
Limited onboard fuel.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Jim on 11/19/2016 08:36 PM

Skylon, rather than SABRE also changes the business model from a sole builder /sole operator model to a sole builder multiple operators model.configuration.  The closest this has been approached is the Soyuz and that's still months between launches.

More likely not.  It still could be too complex to be run by anybody other than the developer/manufacturer.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: knowles2 on 11/19/2016 08:40 PM
Sabre is conceived as a zero to ~Mach 5 air breathing engine, then transitioning to rocket mode.  Why would the test vehicle need to be launched at speed/altitude?
Limited onboard fuel.
[url]
http://www.orbital-access.com/projects.html[url]

I think these guys are gunning to be the ones that build Skylon. I wouldn't be surprise if we seem some of the technologies needed for the construction Skylon fuselage and control systems and other technologies needed for the vehicle.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: oddbodd on 11/19/2016 10:53 PM

http://www.orbital-access.com/projects.html (http://www.orbital-access.com/projects.html)

I think these guys are gunning to be the ones that build Skylon. I wouldn't be surprise if we seem some of the technologies needed for the construction Skylon fuselage and control systems and other technologies needed for the vehicle.

From the link you provided:
Quote
The project’s specific targets include an initial horizontal small payload launch system
in service by 2020, as well as a fully reusable system in service by 2030.
The technical and operational discoveries made during the development
of these systems will also lay the foundation for the creation of Skylon in the long-term.

So yeah, it looks like any likely implementation would begin in the 2030's. I was making a bit of a prediction in my previous message, but it looks like I probably nailed it. So best case 2035 - 2040 for a prototype Skylon class SSTO fully-reusable vehicle (assuming available funding) to be available for testing. At this point SpaceX would have had two decades of launches incorporating some level of reusability and making improvements / refinements (i.e. Merlin 1 @~850kN, Raptor @~3000kN, Merlin 2 @~7000kN) and driving down costs. Can Skylon attract the investment in that environment? It's a tough sell now with current launch costs... I understand the proposed program would "retire a lot of risk" as JS19 likes to say, but it will still need many wheelbarrows of £50 notes to create the Skylon class vehicle.

And here's some sad thoughts for you. While it is not impossible, it becomes ever more unlikely that Alan Bond (~72) will be around to see Skylon fly. John Scott-Scott has unfortunately already passed away, never knowing if Skylon will even be built or not. Richard Varvill (~55) has a fighting chance, although if he were to retire at 65 he'd not have any involvement with the Skylon program.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: oddbodd on 11/19/2016 11:13 PM
http://www.orbital-access.com/projects.html (http://www.orbital-access.com/projects.html)

I think these guys are gunning to be the ones that build Skylon. I wouldn't be surprise if we seem some of the technologies needed for the construction Skylon fuselage and control systems and other technologies needed for the vehicle.

Actually having read a bit around them, I don't think these are likely to be the ones building Skylon. It seems they are very young (<18 months) and have a handful of staff. Or can someone point me toward some resource that shows they are more than just a PowerPoint company.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: ChrisWilson68 on 11/20/2016 01:19 AM
The issue as I see it is that the original Skylon SSTO concept had a narrow(-ish) window of opportunity. It made sense while rockets were expendable, but we now have Space X pushing the envelope on reusability, and if they reduce costs enough (not necessarily down to theoretical Skylon levels) then the business case for progressing to create Skylon (or similar) will not be attractive enough to pull in the needed investment. This new site seems to push SSTO Skylon further and further out, giving the likes of Space X more and more time to consolidate and lock down the market. So SSTO Skylon is at risk of withering on the vine, and without it (or something similar) it's not clear that we will ever reach SSTO and airliner style operations. Without those two things space access is never going to progress much beyond what we already have.

It's too bad you're so hung up on SSTO that you can't see that both SpaceX and Blue Origin are well on their way to providing what you're really looking for, which is low cost made possible by full reusability.

Reusability is the key, not SSTO.  The people who are actually having success with reusuability have done the analysis and realized that SSTO actually makes things more expensive than staging for fully-reusable systems.

A Skylon SSTO depends on lots of expensive techniques, such as using hydrogen, very high mass ratios, and thermal protection with properties beyond anything ever successfully used before.  Staging is the cheaper technique for fully-reusable, low-cost space launch.

Even Space X with a partially reusable rocket will take weeks (if not months) to reintegrate for a second launch.

Not according to Elon Musk.

It baffles me why you would believe REL's optimistic predictions about Skylon, when REL hasn't flown anything but not believe SpaceX's predictions, when SpaceX is trying something much more conservative and has a lot of real-world experience and a track record of success.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: knowles2 on 11/20/2016 01:23 AM
http://www.orbital-access.com/projects.html (http://www.orbital-access.com/projects.html)

I think these guys are gunning to be the ones that build Skylon. I wouldn't be surprise if we seem some of the technologies needed for the construction Skylon fuselage and control systems and other technologies needed for the vehicle.

Actually having read a bit around them, I don't think these are likely to be the ones building Skylon. It seems they are very young (<18 months) and have a handful of staff. Or can someone point me toward some resource that shows they are more than just a PowerPoint company.

The age of the company means nothing, a lot of the facilities needed for Skylon would have to built from scratch anyway no matter who took on the project and their orbital 500 presuming it becomes operational should give plenty of experience as a airframe manufacture and experience of putting stuff into space an give some of the facilities needed for Skylon. More concerning is that so far they only have 2 million euros and a bit of money from UK Space Agency. Somedays I wish I had a idea that would make me billions so I could fund this properly.

Reaction engines spent years being a powerpoint company.

Quote
And here's some sad thoughts for you. While it is not impossible, it becomes ever more unlikely that Alan Bond (~72) will be around to see Skylon fly. John Scott-Scott has unfortunately already passed away, never knowing if Skylon will even be built or not. Richard Varvill (~55) has a fighting chance, although if he were to retire at 65 he'd not have any involvement with the Skylon program.
Hopefully they will see the prototype vehicle flying.

I hope we will see quicker process that 2035-2040. I think the earliest is 2030 for Sky launch.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: oddbodd on 11/20/2016 02:57 AM
The issue as I see it is that the original Skylon SSTO concept had a narrow(-ish) window of opportunity. It made sense while rockets were expendable, but we now have Space X pushing the envelope on reusability, and if they reduce costs enough (not necessarily down to theoretical Skylon levels) then the business case for progressing to create Skylon (or similar) will not be attractive enough to pull in the needed investment. This new site seems to push SSTO Skylon further and further out, giving the likes of Space X more and more time to consolidate and lock down the market. So SSTO Skylon is at risk of withering on the vine, and without it (or something similar) it's not clear that we will ever reach SSTO and airliner style operations. Without those two things space access is never going to progress much beyond what we already have.

It's too bad you're so hung up on SSTO that you can't see that both SpaceX and Blue Origin are well on their way to providing what you're really looking for, which is low cost made possible by full reusability.
I'll agree that SpaceX are well on the way to partial reusability, albeit without having actually reflown a used first stage yet. I don't think second stage reusability is a given yet. Future development/testing will determine if it's something SpaceX can justify offering to customers, or if the trade-offs are too high, and the second stage remains expendable.

I'd argue about Blue Origin being well on the way, as we're (or at least I'm :) ) talking about LEO and up. BO have gone up, and come back down in a relatively small rocket. Maybe the tech will translate to a larger rocket easily, allowing LEO, and making it closer to SpaceX, but they are a ways-away at the moment.

Reusability is the key, not SSTO.  The people who are actually having success with reusuability have done the analysis and realized that SSTO actually makes things more expensive than staging for fully-reusable systems.
As no one has done SSTO yet, the only people "having success" are the ones doing staging. Does this not risk a degree of confirmation bias?

A Skylon SSTO depends on lots of expensive techniques, such as using hydrogen, very high mass ratios, and thermal protection with properties beyond anything ever successfully used before.  Staging is the cheaper technique for fully-reusable, low-cost space launch.
I'll concede that hydrogen is a pain to deal with compared to other rocket fuels, incurring more cost. On the other hand it's a lot less toxic than some of the stuff used. And at a real stretch it could be carbon neutral by the time Skylon would be ready.

I'll pass on the mass ratio. IANARS (I am not a rocket scientist) and I don't follow how high mass ratio = expensive technique.

On the TPS, I was under the impression that DLR concluded that the reentry conditions were not too bad. Or is it the mass vs. performance that is the "beyond anything ever successfully used before" bit?

Even Space X with a partially reusable rocket will take weeks (if not months) to reintegrate for a second launch.

Not according to Elon Musk.

It baffles me why you would believe REL's optimistic predictions about Skylon, when REL hasn't flown anything but not believe SpaceX's predictions, when SpaceX is trying something much more conservative and has a lot of real-world experience and a track record of success.

Assuming this report is accurate: http://www.theverge.com/2016/4/8/11395606/elon-musk-spacex-landing-falcon-9-relaunch-schedule-date

"Ultimately, SpaceX hopes to reduce the turnaround time for its rockets to a couple of weeks."

If the launch of the reused first stage goes ahead in January, it will have been around nine months. I'm sure they'll keep cutting that down, but I also read that a single launchpad can only launch once every few weeks, as the pads need attention too. Of course SpaceX could start building new launch pads I suppose.

And just to point out that I don't believe REL's predictions, because belief is for religions. I do think that so far all the external studies, audits and checks have come back saying that it is not impossible. Technical challenges sure, but not beyond the realm of the possible. So I do hope they can deliver (although I'm increasingly pessimistic as stated elsewhere) because if they do, I think it will move space transport into a new phase. Think PC's, boring utilitarian grey boxes that got the job done for years... then along came the Macs which dragged PC's out of the dark ages. Right now it feels like space needs a Mac moment if it is to be much more to human race than it is now. Whether that's Skylon or some other thing I can't predict.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: oddbodd on 11/20/2016 03:29 AM
http://www.orbital-access.com/projects.html (http://www.orbital-access.com/projects.html)

I think these guys are gunning to be the ones that build Skylon. I wouldn't be surprise if we seem some of the technologies needed for the construction Skylon fuselage and control systems and other technologies needed for the vehicle.

Actually having read a bit around them, I don't think these are likely to be the ones building Skylon. It seems they are very young (<18 months) and have a handful of staff. Or can someone point me toward some resource that shows they are more than just a PowerPoint company.

The age of the company means nothing, a lot of the facilities needed for Skylon would have to built from scratch anyway no matter who took on the project and their orbital 500 presuming it becomes operational should give plenty of experience as a airframe manufacture and experience of putting stuff into space an give some of the facilities needed for Skylon. More concerning is that so far they only have 2 million euros and a bit of money from UK Space Agency. Somedays I wish I had a idea that would make me billions so I could fund this properly.
The image for the Orbital 500 looks more like a rocket with winglets than an airframe to me so I'm not sure how useful that bestowed experience would be. Agreed that the lack of money is a worry. I suspect that right now they don't have the required engineers and depth of experience to pull this off. That 2 million won't go far (I think rocket scientists are well paid ;) ) so they'll need investment. I think that might be hard to drum up, at least from what info is available publicly.

Never mind "Somedays", every time I read this forum :)

Reaction engines spent years being a powerpoint company.
I kinda think that's a mis-characterization. REL was founded by three engineers, who I'm pretty sure were working on the engineering problems pretty much immediately after being founded if not before. By contrast Orbital Access seems to be a company whose only apparent staff are CEO's, Market and Business Development and similar board level positions. Granted the CEO is an engineer, but the news, history and feeds are very uninformative. There's no sense of engineering going on, at least from the website, and a presentation by the CEO I found on YouTube. https://www.youtube.com/watch?v=dzWXYgh4Ejw (https://www.youtube.com/watch?v=dzWXYgh4Ejw)

Quote
And here's some sad thoughts for you. While it is not impossible, it becomes ever more unlikely that Alan Bond (~72) will be around to see Skylon fly. John Scott-Scott has unfortunately already passed away, never knowing if Skylon will even be built or not. Richard Varvill (~55) has a fighting chance, although if he were to retire at 65 he'd not have any involvement with the Skylon program.
Hopefully they will see the prototype vehicle flying.

I hope we will see quicker process that 2035-2040. I think the earliest is 2030 for Sky launch.

According to the blurb 2030 was for the small payload launch system. Skylon was after that, building on the experience. I was being optimistic that the SPLS would allow them to create Skylon quicker, but 5 years is not long for something like Skylon I think, even with that previous experience. Unless someone else comes along with a bulging sack of cash and a fire in their belly I think it's unlikely we'll see Skylon by 2030.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Paul451 on 11/20/2016 05:42 AM
I'll pass on the mass ratio. IANARS (I am not a rocket scientist) and I don't follow how high mass ratio = expensive technique.

There's an engineering rule-of-thumb that I was given years ago: for every 10% reduction in mass or thickness of a part, the life-span halves. (Or every 10% increase/double.) In practice, you end up substituting complexity for mass. The greater engineering complexity then increases cost-of-development.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: ChrisWilson68 on 11/20/2016 08:40 AM
I'll agree that SpaceX are well on the way to partial reusability, albeit without having actually reflown a used first stage yet. I don't think second stage reusability is a given yet. Future development/testing will determine if it's something SpaceX can justify offering to customers, or if the trade-offs are too high, and the second stage remains expendable.

The point is that SpaceX is a lot closer to second-stage reusability than Skylon is to SSTO.

I'd argue about Blue Origin being well on the way, as we're (or at least I'm :) ) talking about LEO and up. BO have gone up, and come back down in a relatively small rocket. Maybe the tech will translate to a larger rocket easily, allowing LEO, and making it closer to SpaceX, but they are a ways-away at the moment.

Again, the comparison is with Skylon.  Blue Origin is far closer to fully-reusable orbital launch than Skylon is.

Reusability is the key, not SSTO.  The people who are actually having success with reusuability have done the analysis and realized that SSTO actually makes things more expensive than staging for fully-reusable systems.
As no one has done SSTO yet, the only people "having success" are the ones doing staging. Does this not risk a degree of confirmation bias?

Both Musk and Bezos came to the space world as complete outsiders, without any bias.  The considered the options and both chose two-stage reusable systems with horizontal take-off and landing.  No confirmation bias there.

I'll concede that hydrogen is a pain to deal with compared to other rocket fuels, incurring more cost. On the other hand it's a lot less toxic than some of the stuff used.

Neither methane nor RP-1 is particularly toxic -- not toxic enough to be more expensive to deal with safely than hydrogen.  And what we're talking about here is what's less expensive.

And at a real stretch it could be carbon neutral by the time Skylon would be ready.

So could methane.  Anyway, again, it doesn't affect the cost, which is what we're talking about here.

On the TPS, I was under the impression that DLR concluded that the reentry conditions were not too bad. Or is it the mass vs. performance that is the "beyond anything ever successfully used before" bit?

It depends on what you consider "not too bad".  The projections are something like 830 Celsius.  It will require active cooling.  Skylon is supposed to have a ceramic skin on a huge scale to handle that.  The only other operational vehicle to ever try ceramic TPS was shuttle, and we all know how many surprise issues it had that weren't anticipated, and how much that drove costs through the roof and resulted in a dead crew.

Not according to Elon Musk.

It baffles me why you would believe REL's optimistic predictions about Skylon, when REL hasn't flown anything but not believe SpaceX's predictions, when SpaceX is trying something much more conservative and has a lot of real-world experience and a track record of success.

Assuming this report is accurate: http://www.theverge.com/2016/4/8/11395606/elon-musk-spacex-landing-falcon-9-relaunch-schedule-date

"Ultimately, SpaceX hopes to reduce the turnaround time for its rockets to a couple of weeks."

That is not correct.  Musk has said on various occasions that the long-term target is a turn-around time of hours for the first stage and 24 hours for the upper stage.

They may or may not achieve that target, but the target is just as aggressive as that for Skylon.  And, since Skylon has lower margins available because it needs such high performance to make up for the lack of staging that it's far more likely SpaceX will meet its targets than that Skylon will.

If the launch of the reused first stage goes ahead in January, it will have been around nine months.

And that's completely irrelevant, because it's during the development program.

I'm sure they'll keep cutting that down, but I also read that a single launchpad can only launch once every few weeks, as the pads need attention too. Of course SpaceX could start building new launch pads I suppose.

SpaceX has already done launches off the same pad just two weeks apart and they have plans to automate the whole process and have the pad ready for multiple launches the same day.

Pad procedures historically have required a few weeks between launches just because there's no point in designing them for faster turn-around for expensive expendable vehicles.  Once vehicles can be reused and the launch rates can go up, procedures will change to allow the quick turn-around time needed.

And just to point out that I don't believe REL's predictions, because belief is for religions. I do think that so far all the external studies, audits and checks have come back saying that it is not impossible. Technical challenges sure, but not beyond the realm of the possible.

And the same is true for SpaceX and Blue Origin too.

And yet you stated sadness that Skylon seems unlikely to happen because it meant we'll never get cheap spaceflight.

iIf you're going to give REL the benefit of the doubt, give SpaceX and Blue Origin at least as much.

So I do hope they can deliver (although I'm increasingly pessimistic as stated elsewhere) because if they do, I think it will move space transport into a new phase. Think PC's, boring utilitarian grey boxes that got the job done for years... then along came the Macs which dragged PC's out of the dark ages. Right now it feels like space needs a Mac moment if it is to be much more to human race than it is now. Whether that's Skylon or some other thing I can't predict.

The thing is, you are predicting.  You're predicting it won't be SpaceX or Blue Origin.  Why not?  Because their solutions aren't as aesthetically pleasing?  Aesthetically pleasing doesn't give us cheap access to space.  Good engineering choices will do that.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: t43562 on 11/20/2016 11:39 AM
The thing is, you are predicting.  You're predicting it won't be SpaceX or Blue Origin.  Why not?  Because their solutions aren't as aesthetically pleasing?  Aesthetically pleasing doesn't give us cheap access to space.  Good engineering choices will do that.

This is the Skylon thread, we don't come here to talk about how it isn't any good and how we should all give up now and pray at other altars.  That would make the thread pointless.  In any case, as industries get bigger they get more cut-throat and even small improvements make a great difference.   
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: lkm on 11/20/2016 11:42 AM
I'll agree that SpaceX are well on the way to partial reusability, albeit without having actually reflown a used first stage yet. I don't think second stage reusability is a given yet. Future development/testing will determine if it's something SpaceX can justify offering to customers, or if the trade-offs are too high, and the second stage remains expendable.

The point is that SpaceX is a lot closer to second-stage reusability than Skylon is to SSTO.

I'd argue about Blue Origin being well on the way, as we're (or at least I'm :) ) talking about LEO and up. BO have gone up, and come back down in a relatively small rocket. Maybe the tech will translate to a larger rocket easily, allowing LEO, and making it closer to SpaceX, but they are a ways-away at the moment.

Again, the comparison is with Skylon.  Blue Origin is far closer to fully-reusable orbital launch than Skylon is.

Reusability is the key, not SSTO.  The people who are actually having success with reusuability have done the analysis and realized that SSTO actually makes things more expensive than staging for fully-reusable systems.
As no one has done SSTO yet, the only people "having success" are the ones doing staging. Does this not risk a degree of confirmation bias?

Both Musk and Bezos came to the space world as complete outsiders, without any bias.  The considered the options and both chose two-stage reusable systems with horizontal take-off and landing.  No confirmation bias there.

I'll concede that hydrogen is a pain to deal with compared to other rocket fuels, incurring more cost. On the other hand it's a lot less toxic than some of the stuff used.

Neither methane nor RP-1 is particularly toxic -- not toxic enough to be more expensive to deal with safely than hydrogen.  And what we're talking about here is what's less expensive.

And at a real stretch it could be carbon neutral by the time Skylon would be ready.

So could methane.  Anyway, again, it doesn't affect the cost, which is what we're talking about here.

On the TPS, I was under the impression that DLR concluded that the reentry conditions were not too bad. Or is it the mass vs. performance that is the "beyond anything ever successfully used before" bit?

It depends on what you consider "not too bad".  The projections are something like 830 Celsius.  It will require active cooling.  Skylon is supposed to have a ceramic skin on a huge scale to handle that.  The only other operational vehicle to ever try ceramic TPS was shuttle, and we all know how many surprise issues it had that weren't anticipated, and how much that drove costs through the roof and resulted in a dead crew.

Not according to Elon Musk.

It baffles me why you would believe REL's optimistic predictions about Skylon, when REL hasn't flown anything but not believe SpaceX's predictions, when SpaceX is trying something much more conservative and has a lot of real-world experience and a track record of success.

Assuming this report is accurate: http://www.theverge.com/2016/4/8/11395606/elon-musk-spacex-landing-falcon-9-relaunch-schedule-date

"Ultimately, SpaceX hopes to reduce the turnaround time for its rockets to a couple of weeks."

That is not correct.  Musk has said on various occasions that the long-term target is a turn-around time of hours for the first stage and 24 hours for the upper stage.

They may or may not achieve that target, but the target is just as aggressive as that for Skylon.  And, since Skylon has lower margins available because it needs such high performance to make up for the lack of staging that it's far more likely SpaceX will meet its targets than that Skylon will.

If the launch of the reused first stage goes ahead in January, it will have been around nine months.

And that's completely irrelevant, because it's during the development program.

I'm sure they'll keep cutting that down, but I also read that a single launchpad can only launch once every few weeks, as the pads need attention too. Of course SpaceX could start building new launch pads I suppose.

SpaceX has already done launches off the same pad just two weeks apart and they have plans to automate the whole process and have the pad ready for multiple launches the same day.

Pad procedures historically have required a few weeks between launches just because there's no point in designing them for faster turn-around for expensive expendable vehicles.  Once vehicles can be reused and the launch rates can go up, procedures will change to allow the quick turn-around time needed.

And just to point out that I don't believe REL's predictions, because belief is for religions. I do think that so far all the external studies, audits and checks have come back saying that it is not impossible. Technical challenges sure, but not beyond the realm of the possible.

And the same is true for SpaceX and Blue Origin too.

And yet you stated sadness that Skylon seems unlikely to happen because it meant we'll never get cheap spaceflight.

iIf you're going to give REL the benefit of the doubt, give SpaceX and Blue Origin at least as much.

So I do hope they can deliver (although I'm increasingly pessimistic as stated elsewhere) because if they do, I think it will move space transport into a new phase. Think PC's, boring utilitarian grey boxes that got the job done for years... then along came the Macs which dragged PC's out of the dark ages. Right now it feels like space needs a Mac moment if it is to be much more to human race than it is now. Whether that's Skylon or some other thing I can't predict.

The thing is, you are predicting.  You're predicting it won't be SpaceX or Blue Origin.  Why not?  Because their solutions aren't as aesthetically pleasing?  Aesthetically pleasing doesn't give us cheap access to space.  Good engineering choices will do that.

Except, accurate or not, all of that is irrelevant.
Skylon, should it ever be built in the manner described, won't be competing with SpaceX or Blue Orgin because neither of them intend to be selling launch vehicles to other launch companies in 2030 and there are dozens of other launch providers who intend to still be in business in 2030 and also thousands of payloads that can't launch on American launch vehicles to fly with them.
 So the actual question is what is everybody other than SpaceX and Blue Orign launching, because that is Skylon's
market. Skylon doesn't have to be better than falcon or new Glenn, just better than any other option to compete with them. Or alternatively Skylon doesn't need to be faster than the bear, just faster than anybody else running from it.
The only situation in which Skylon and falcon would directly compete in the manner you've described  would be if SpaceX were to consider switching to a Skylon fleet so that it internally could focus on Mars and infrastructure.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Robotbeat on 11/20/2016 01:55 PM
Also, I have to say the idea of a civil hypersonic transport is super exciting to me, too. And it'd use hydrogen, so technically this can be done pretty easily with zero carbon emissions! Very neat. :)

You do realize that the vast majority (~95%) of hydrogen comes from the processing of fossil fuels? Electrolysis (i.e. using wind, hydro or solar PV) is highly inefficient. There are laboratory scale experiments that may eventually bear fruit (i.e. algae), but I certainly wouldn't say that currently hydrogen can be done pretty easily with zero carbon emissions.
Yes I am. And untrue it's inefficient. 65-70% efficient electrolysis isn't unheard of for large plants. It's completely inaccurate to label that as mere lab-scale. And it can easily be done with zero emissions, it's just that natural gas is super duper cheap right now.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Coastal Ron on 11/20/2016 03:56 PM
[Except, accurate or not, all of that is irrelevant.
Skylon, should it ever be built in the manner described, won't be competing with SpaceX or Blue Orgin because neither of them intend to be selling launch vehicles to other launch companies in 2030 and there are dozens of other launch providers who intend to still be in business in 2030 and also thousands of payloads that can't launch on American launch vehicles to fly with them.
 So the actual question is what is everybody other than SpaceX and Blue Orign launching, because that is Skylon's market.

It doesn't matter if Skylon intends to be a vehicle builder or a service provider, since the market that they are addressing is moving mass to space - which is the same market that Blue Origin and SpaceX are addressing.  The only difference is who owns the vehicles, which is really immaterial when discussing supply and demand.

For instance, if the cost of buying and operating a Skylon does not result in the ability of a service provider to offer a competitive $/kg to orbit price, then no one will buy a Skylon.

Quote
Skylon doesn't have to be better than falcon or new Glenn, just better than any other option to compete with them. Or alternatively Skylon doesn't need to be faster than the bear, just faster than anybody else running from it.

To a degree that is true, but only to a degree.  For instance, "the payload market" does want competition, and is willing to buy services from companies that are not the lowest bidders in order to ensure that there are enough choices to support competition and redundancy.

However, that may mean that there is only a market opportunity for (as an example) five launch service providers.  So the situation ends up being like the musical chairs game, where those that are the least competitive are trying to out maneuver each other in order to continue being one of the chosen competitors - which if you don't have deep pockets, can create a fiscal death spiral.

So no matter what, if Skylon wants to be a big success, they have to be one of the least expensive options for moving mass to space.  Anything less means their potential growth won't happen the way they need it to happen.

Quote
The only situation in which Skylon and falcon would directly compete in the manner you've described  would be if SpaceX were to consider switching to a Skylon fleet so that it internally could focus on Mars and infrastructure.

Assuming reusability is perfected, SpaceX will have the advantage of being able to iterate their existing Falcon 9 design to make it more and more reliable and to drive down costs.

Because of that, the Skylon cost advantage over the Falcon 9 would have to be not only obvious, but significantly better than the Falcon 9 in order for SpaceX to consider abandoning the Falcon 9.  Again, this gets back to the supply and demand issue, and being in the top group of service providers.

But at the pace Skylon is currently going at, SpaceX won't have to worry about their marketshare for at least another decade - at which point their successor to the Falcon 9 (whatever that will be) may already be getting ready for it's own launch.  Skylon needs to go faster...
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: oddbodd on 11/20/2016 04:08 PM
Also, I have to say the idea of a civil hypersonic transport is super exciting to me, too. And it'd use hydrogen, so technically this can be done pretty easily with zero carbon emissions! Very neat. :)

You do realize that the vast majority (~95%) of hydrogen comes from the processing of fossil fuels? Electrolysis (i.e. using wind, hydro or solar PV) is highly inefficient. There are laboratory scale experiments that may eventually bear fruit (i.e. algae), but I certainly wouldn't say that currently hydrogen can be done pretty easily with zero carbon emissions.
Yes I am. And untrue it's inefficient. 65-70% efficient electrolysis isn't unheard of for large plants. It's completely inaccurate to label that as mere lab-scale. And it can easily be done with zero emissions, it's just that natural gas is super duper cheap right now.

Hmmm. The "highly inefficient" was supposed to be compared to pulling it out of fossil fuels, where I thought the efficiency was much higher, making the resulting fuel cheaper. However, I didn't check my memory that electrolysis was lower, and they're actually pretty close. Apologies for my mistake.

That begs the question, why is the vast majority produced and used is from fossil fuels? Is it because the electricity used is often coming from fossil fuels anyway, so the conversion suffers a double-dip on the efficiency? Might as well just strip it straight out of the fuel. Sure you could stipulate that the electricity has to be from renewables, although historically that has been more expensive. We're approaching the point where electricity from renewables are getting close to fossil fuels, so then it would make sense that the electrolysis would start to take more of the market. As you say, gas being cheap is not going to help that transition. :(

The lab-scale comment was not talking about electroysis. I was talking about experimental stuff like algae bioreactors, and photocatalytic water splitting.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: lkm on 11/20/2016 04:53 PM
[Except, accurate or not, all of that is irrelevant.
Skylon, should it ever be built in the manner described, won't be competing with SpaceX or Blue Orgin because neither of them intend to be selling launch vehicles to other launch companies in 2030 and there are dozens of other launch providers who intend to still be in business in 2030 and also thousands of payloads that can't launch on American launch vehicles to fly with them.
 So the actual question is what is everybody other than SpaceX and Blue Orign launching, because that is Skylon's market.

It doesn't matter if Skylon intends to be a vehicle builder or a service provider, since the market that they are addressing is moving mass to space - which is the same market that Blue Origin and SpaceX are addressing.  The only difference is who owns the vehicles, which is really immaterial when discussing supply and demand.

For instance, if the cost of buying and operating a Skylon does not result in the ability of a service provider to offer a competitive $/kg to orbit price, then no one will buy a Skylon.
The market Skylon is addressing is the market of people who want to offer launch services and that market is substantially larger than just SpaceX and Blue origin and that is not an immaterial difference.
Skylon doesn't have to be better than falcon or new Glenn, just better than any other option to compete with them. Or alternatively Skylon doesn't need to be faster than the bear, just faster than anybody else running from it.

To a degree that is true, but only to a degree.  For instance, "the payload market" does want competition, and is willing to buy services from companies that are not the lowest bidders in order to ensure that there are enough choices to support competition and redundancy.

However, that may mean that there is only a market opportunity for (as an example) five launch service providers.  So the situation ends up being like the musical chairs game, where those that are the least competitive are trying to out maneuver each other in order to continue being one of the chosen competitors - which if you don't have deep pockets, can create a fiscal death spiral.

So no matter what, if Skylon wants to be a big success, they have to be one of the least expensive options for moving mass to space.  Anything less means their potential growth won't happen the way they need it to happen.
Five launch providers is substantially fewer that currently exist today servicing a much smaller market but even so assuming two of them are SpaceX and Blue Origin then the other three have to be launching something, so Skylon only has to be the third most cost effective launch vehicle to own a majority of this hypothetical market because, as I've pointed out, it's not competing with falcon and new Glen.

The only situation in which Skylon and falcon would directly compete in the manner you've described  would be if SpaceX were to consider switching to a Skylon fleet so that it internally could focus on Mars and infrastructure.

Assuming reusability is perfected, SpaceX will have the advantage of being able to iterate their existing Falcon 9 design to make it more and more reliable and to drive down costs.

Because of that, the Skylon cost advantage over the Falcon 9 would have to be not only obvious, but significantly better than the Falcon 9 in order for SpaceX to consider abandoning the Falcon 9.  Again, this gets back to the supply and demand issue, and being in the top group of service providers.

But at the pace Skylon is currently going at, SpaceX won't have to worry about their marketshare for at least another decade - at which point their successor to the Falcon 9 (whatever that will be) may already be getting ready for it's own launch.  Skylon needs to go faster...
My point was the only situation where a competitive comparison was warranted was so deeply unlikely and hypothetical that it wasn't worth having.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: TrevorMonty on 11/20/2016 05:46 PM
IMO Skylon need SpaceX and Blue RLVs to build market demand that will justify huge investment required for full scale Skylon. The competition sometimes helps businesses.

Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: ChrisWilson68 on 11/20/2016 07:32 PM
IMO Skylon need SpaceX and Blue RLVs to build market demand that will justify huge investment required for full scale Skylon. The competition sometimes helps businesses.

Yes, competition sometimes helps businesses.  But only if the business has some kind of advantage over the competition that lets it take some market share.

What people are arguing here is that in this instance the competition is so efficient that it makes it very hard for Skylon to have an advantage that is worth the huge development cost.  Even discounting the development cost, there's reason to believe Skylon is likely to be more expensive on a marginal basis than the competition from SpaceX and Blue Origin long before Skylon could actually be built.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: lkm on 11/20/2016 08:21 PM
IMO Skylon need SpaceX and Blue RLVs to build market demand that will justify huge investment required for full scale Skylon. The competition sometimes helps businesses.

Yes, competition sometimes helps businesses.  But only if the business has some kind of advantage over the competition that lets it take some market share.

What people are arguing here is that in this instance the competition is so efficient that it makes it very hard for Skylon to have an advantage that is worth the huge development cost.  Even discounting the development cost, there's reason to believe Skylon is likely to be more expensive on a marginal basis than the competition from SpaceX and Blue Origin long before Skylon could actually be built.

Except that, no.
If competition expands a new market a competitor doesn't need some kind of technical advantage over the first mover to take some market share, it just needs to be available in a manner the first mover isn't.
For example the iPhone rapidly expanded the smartphone market upon its launch giving blackberry several years of rapid growth despite selling an inferior product just because the iPhone successfully made a smartphone market but was unable to fill all of it. Today the iPhone is probably the best smartphone you can buy but is only 12% of global phones because Apple doesn't allow any other company to make them, so ever other phone maker has to make Android phones. That is the argument. SpaceX can build iPhones but that just means everybody else has to use Android. Is Skylon Android?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: ChrisWilson68 on 11/20/2016 08:36 PM
IMO Skylon need SpaceX and Blue RLVs to build market demand that will justify huge investment required for full scale Skylon. The competition sometimes helps businesses.

Yes, competition sometimes helps businesses.  But only if the business has some kind of advantage over the competition that lets it take some market share.

What people are arguing here is that in this instance the competition is so efficient that it makes it very hard for Skylon to have an advantage that is worth the huge development cost.  Even discounting the development cost, there's reason to believe Skylon is likely to be more expensive on a marginal basis than the competition from SpaceX and Blue Origin long before Skylon could actually be built.

Except that, no.
If competition expands a new market a competitor doesn't need some kind of technical advantage over the first mover to take some market share, it just needs to be available in a manner the first mover isn't.
For example the iPhone rapidly expanded the smartphone market upon its launch giving blackberry several years of rapid growth despite selling an inferior product just because the iPhone successfully made a smartphone market but was unable to fill all of it. Today the iPhone is probably the best smartphone you can buy but is only 12% of global phones because Apple doesn't allow any other company to make them, so ever other phone maker has to make Android phones. That is the argument. SpaceX can build iPhones but that just means everybody else has to use Android. Is Skylon Android?

None of that is remotely true.  The iPhone wasn't a success initially because nobody else had the capacity to fill the market.  It was a success initially because it offered an experience that was differentiated from the competition.

The split today between Android and iPhone is because there's a different price/features/experience trade-off for different phones.  Some consumers like iPhones better, some Android.  Some have more money to spend, some less.

Launch services don't work that way.  They're not a consumer market where the customers have a wide variety of different preferences.  The customers basically just want to get their payloads from point A to point B.  And the idea that somehow the market would grow so quickly that SpaceX and Blue Origin wouldn't be able to meet demand is just silly.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Coastal Ron on 11/20/2016 09:09 PM
It doesn't matter if Skylon intends to be a vehicle builder or a service provider, since the market that they are addressing is moving mass to space - which is the same market that Blue Origin and SpaceX are addressing.  The only difference is who owns the vehicles, which is really immaterial when discussing supply and demand.

For instance, if the cost of buying and operating a Skylon does not result in the ability of a service provider to offer a competitive $/kg to orbit price, then no one will buy a Skylon.
The market Skylon is addressing is the market of people who want to offer launch services and that market is substantially larger than just SpaceX and Blue origin and that is not an immaterial difference.

Sorry, but no.  You are not looking at the prime source of the demand.

For instance, no one will buy the Skylon to operate their own transportation business if the Skylon would be the most expensive transportation option.  For example:

The SpaceX current model (i.e. they build and operate their own launchers):
Falcon 9 production costs + SpaceX launch operations costs + SpaceX profit = customer price

The Skylon model that you are suggesting (i.e. the Boeing model):
Skylon production costs + Skylon profit + Operator capital equipment costs (purchase loan, maintenance, etc.) + Operator launch operations costs + Operator profit = customer price

So you can see that builder/operators have an advantage where they skip one layer of profit that otherwise would be added, and that could be enough of a difference to wipe away the competitive advantage of what otherwise would be a lower cost Skylon service.

Until the purchase price and maintenance costs of a Skylon are known, it's hard to argue that the Skylon can beat the price of current competitors.

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Five launch providers is substantially fewer that currently exist today servicing a much smaller market but even so assuming two of them are SpaceX and Blue Origin then the other three have to be launching something, so Skylon only has to be the third most cost effective launch vehicle to own a majority of this hypothetical market because, as I've pointed out, it's not competing with falcon and new Glen.

Again, the number "5" was just an example, and not meant to represent reality.

However I would posit that the top three providers winning the most business will have a major profit advantage over the everyone else.  And in case you haven't looked, other than SpaceX and Blue Origin, everyone else in the launch business is state supported in some way, so Skylon would be competing against a lot of deep pockets.  How long could Skylon engage in a price war against nation-states?

I think the Skylon is an interesting concept, and it appeals to my wish that there was such a technology.  But just because it could be technically capable of doing what it's designed to do doesn't mean it could be profitable at doing it.  The two don't always go together.

But as long as someone is willing to put money into the Skylon, I'll keep watching it...
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/20/2016 09:55 PM
It's too bad you're so hung up on SSTO that you can't see that both SpaceX and Blue Origin are well on their way to providing what you're really looking for, which is low cost made possible by full reusability.
Well on their way? Blue is nowhere near orbital yet and SX are nowhere near reflying the F9 stage and when they do it's looking increasingly like there will be no price discount for flying a reusable.

And just to be clear. It's the $/Kg price I care about, not how much it costs someone to make a LV.

So while SX have advanced technically we're seeing no substantial price cut, and running any sort of price simulation game will show they are unlikely to ever with a semi expendable system.
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Reusability is the key, not SSTO.  The people who are actually having success with reusuability have done the analysis and realized that SSTO actually makes things more expensive than staging for fully-reusable systems.
And if you're committed to a VTOL rocket then it always will be.  :(
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A Skylon SSTO depends on lots of expensive techniques, such as using hydrogen, very high mass ratios, and thermal protection with properties beyond anything ever successfully used before.  Staging is the cheaper technique for fully-reusable, low-cost space launch.
Using actual facts. LH2 is roughly 1/8 the cost of NTO/UDMH and a hell of a lot safer to handle, chich might explain why the Titan was retired decades ago.  It's bad to try retrofitting LH2 to an existing system however, somewhat like adding pre-cooled propellants into a system that was not designed for them from day one.

You need to stop with your claim about "high mass ratios." SABRE enables low mass ratios and hence allows a greater fraction of the GTOW to be structure.

Your constant repetition of this statement is really starting to make you sound like a troll

Do you want to be treated like a troll?

As for the TPS  what exactly do you mean "Beyond anything used before" ?

Doesn't by definition any reusable vehicle have to do this. Had SX succeeded in getting their F9 to have  a fully reusable 2nd stage it would have needed the same, as will ITS. The only known examples were the "shingles" on a Gemini capsule the tiels and blankets of the Shuttle and (possible) what the X37b uses.

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Not according to Elon Musk.

It baffles me why you would believe REL's optimistic predictions about Skylon, when REL hasn't flown anything but not believe SpaceX's predictions, when SpaceX is trying something much more conservative and has a lot of real-world experience and a track record of success.
Simple. When REL have been fully funded they've delivered on schedule

Musk and SX have never delivered on schedule, hence others comments along the lines of "When I hear an SX schedule I double it."

Personally I add 2-4 years to any IOC date.

SX have always delivered eventually (except in the case of a fully reusable F9, which is quite a big failure of either understanding or delivery on their part, but maybe they will in the end).

Likewise any flight schedule should be taken with a pinch bag of salt. A point regularly made on the SX threads.

2018 on Mars? More like 2020-2022 I think.
None of which I would care about if they seriously had a shot of lowering the price to send a reasonable sized payload to LEO.

So far they have failed to do so.   :(

Both Musk and Bezos came to the space world as complete outsiders, without any bias.  The considered the options and both chose two-stage reusable systems with horizontal take-off and landing.  No confirmation bias there.
Oh, if only they had  :)

IRL Musk wanted to land on Mars and Mars has no runways. Bezos motivation is more obscure. No one suggested it was possible? The projected (honest) development cost of Skylon? REL's desire not to entangled in the US interpretation of ITAR? A desire for fast results?
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It depends on what you consider "not too bad".  The projections are something like 830 Celsius.  It will require active cooling.  Skylon is supposed to have a ceramic skin on a huge scale to handle that.  The only other operational vehicle to ever try ceramic TPS was shuttle, and we all know how many surprise issues it had that weren't anticipated, and how much that drove costs through the roof and resulted in a dead crew.
A nice piece of innuendo there. You really do sound like you've got a Marketing background.   :(

PyroSic is a fibre reinforced glass, unlike the Shuttle tiles, which were basically an open cell ceramic foam. It's non porous and AFAIK quite flexible when corrugated (as the Skylon skin is designed to be).
REL don't expect it to be glued to the skin, they expect it to be the skin and they expect it to be de-coupled from the space frame structure by hairpin rivets, a technique first developed for the X20 Dyna-Soar.

it's expected to operate up to 1200c. The areas above that are expected to "transpiration cooled" by water through holes in the surface.  This has actually been flight tested at ICBM reentry speeds in the late 70s/early 80's and works well.
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That is not correct.  Musk has said on various occasions that the long-term target is a turn-around time of hours for the first stage and 24 hours for the upper stage.

They may or may not achieve that target, but the target is just as aggressive as that for Skylon.  And, since Skylon has lower margins available because it needs such high performance to make up for the lack of staging that it's far more likely SpaceX will meet its targets than that Skylon will.
Still pushing that "low margins" line.   :(

Really starting to sound like a troll.
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And that's completely irrelevant, because it's during the development program.
And who knows how long that "development program" could last?
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SpaceX has already done launches off the same pad just two weeks apart and they have plans to automate the whole process and have the pad ready for multiple launches the same day.
IIRC at a busy airport the takeoffs during the day can be as little as 30 seconds apart.

Now that's a fast turnaround for a takeoff system.  :)
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Pad procedures historically have required a few weeks between launches just because there's no point in designing them for faster turn-around for expensive expendable vehicles.  Once vehicles can be reused and the launch rates can go up, procedures will change to allow the quick turn-around time needed.
I guess it depends on what the minimum pad damage done during a launch is.
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And the same is true for SpaceX and Blue Origin too.
What external audit's of SX or Blue's architectures have ever taken place? I'm sure SX's investors have done audits of their accounts but when did SX invite someone in to sanity check ITS? Or SRF9? or SRFH? How about New Shepperd or Glenn?
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iIf you're going to give REL the benefit of the doubt, give SpaceX and Blue Origin at least as much.
Never is a long time.

How about "Not going to happen with any semi-reusable launch system"? Or "Not unless the system is fully reusable at a scale affordable for existing payloads IE 5-25 tonnes, not 100s" ?
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The thing is, you are predicting.  You're predicting it won't be SpaceX or Blue Origin.  Why not?  Because their solutions aren't as aesthetically pleasing?  Aesthetically pleasing doesn't give us cheap access to space.  Good engineering choices will do that.
True.
Wheather that those "good engineering choices" turn out to be made by the companies with the angel investor with very large bank balanced is a question only time will answer.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/20/2016 09:58 PM
I'll pass on the mass ratio. IANARS (I am not a rocket scientist) and I don't follow how high mass ratio = expensive technique.

There's an engineering rule-of-thumb that I was given years ago: for every 10% reduction in mass or thickness of a part, the life-span halves. (Or every 10% increase/double.) In practice, you end up substituting complexity for mass. The greater engineering complexity then increases cost-of-development.
Then how about the reverse?

SABRE, and HTOL allows roughly a 25% structural mass fraction. Demanding for aircraft but astonishingly generous by the standards of previous VTOL SSTO.

The age of the company means nothing, a lot of the facilities needed for Skylon would have to built from scratch anyway no matter who took on the project and their orbital 500 presuming it becomes operational should give plenty of experience as a airframe manufacture and experience of putting stuff into space an give some of the facilities needed for Skylon. More concerning is that so far they only have 2 million euros and a bit of money from UK Space Agency. Somedays I wish I had a idea that would make me billions so I could fund this properly.

Reaction engines spent years being a powerpoint company.
They spent years raising money and doing actual research. The powerpoints were few and far between, as were the website updates.  :( It did mean they have moved fairly quickly when cash has been available.
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Hopefully they will see the prototype vehicle flying.

I hope we will see quicker process that 2035-2040. I think the earliest is 2030 for Sky launch.
That seems plausible.

REL's problems have always been financial. There engineering team was strong from day one but they have lacked entrepreneurship
More likely not.  It still could be too complex to be run by anybody other than the developer/manufacturer.
The truth is no one knows.

But after a 400 flight test programme (which is factored into the budget) they will know very well.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: lkm on 11/21/2016 12:00 AM
IMO Skylon need SpaceX and Blue RLVs to build market demand that will justify huge investment required for full scale Skylon. The competition sometimes helps businesses.

Yes, competition sometimes helps businesses.  But only if the business has some kind of advantage over the competition that lets it take some market share.

What people are arguing here is that in this instance the competition is so efficient that it makes it very hard for Skylon to have an advantage that is worth the huge development cost.  Even discounting the development cost, there's reason to believe Skylon is likely to be more expensive on a marginal basis than the competition from SpaceX and Blue Origin long before Skylon could actually be built.

Except that, no.
If competition expands a new market a competitor doesn't need some kind of technical advantage over the first mover to take some market share, it just needs to be available in a manner the first mover isn't.
For example the iPhone rapidly expanded the smartphone market upon its launch giving blackberry several years of rapid growth despite selling an inferior product just because the iPhone successfully made a smartphone market but was unable to fill all of it. Today the iPhone is probably the best smartphone you can buy but is only 12% of global phones because Apple doesn't allow any other company to make them, so ever other phone maker has to make Android phones. That is the argument. SpaceX can build iPhones but that just means everybody else has to use Android. Is Skylon Android?

None of that is remotely true.  The iPhone wasn't a success initially because nobody else had the capacity to fill the market.  It was a success initially because it offered an experience that was differentiated from the competition.
You've taken the exact opposite of my meaning.
 I said that the iPhone launched with a successful product, a product that redefined what a smartphone was, so the smartphone market expanded, lots of new people wanted smartphones, but Apple couldn't fill that market, Apple launched on only a few carriers in a small number of countries and it took several years before it could even begin to address the entire potential customer bass. Meanwhile Blackberry was already in the smartphone market and had a grossly inferior product but they had global distribution with hundreds of carriers so as Apple expanded the smartphone market they experience a few years of rapid growth soaking up consumer demand for smartphones, even though their product was inferior.

The split today between Android and iPhone is because there's a different price/features/experience trade-off for different phones.  Some consumers like iPhones better, some Android.  Some have more money to spend, some less.

Launch services don't work that way.  They're not a consumer market where the customers have a wide variety of different preferences.  The customers basically just want to get their payloads from point A to point B.  And the idea that somehow the market would grow so quickly that SpaceX and Blue Origin wouldn't be able to meet demand is just silly.

The split between iOS and Android is the split between a proprietary OS written for one company's products and a freely licensable OS used by many companies in competition with each other. If iOS was licensable then many companies would surely use it rather than Android making iPhone clones at many different price points and iOS market share would be much higher but it's not so they have to use Android. Just as the market for operating systems is the companies making the devices so the market for launch vehicles is the launch service providers and the demand that Falcon and New Glenn can't meet is the demand for launch vehicles from launch providers other than SpaceX or Blue Origin. As for whether iOS is better than Android it was your contention that SpaceX will be superior to any potential Skylon which I accepted for the sake of the hypothetical and this analogy.
This is really an integrated versus modular strategy question, integrated is usually better in a fast changing product space but in the long run everything tends to modular.
In the launch market there are many, many different potential point As and many many different point Bs as well many different potential business models and customer preferences, such as responsive flight, minimum cost, maximum payload, that launch providers could use in competition in a Skylon/Falcon/Glenn world.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: lkm on 11/21/2016 12:41 AM
It doesn't matter if Skylon intends to be a vehicle builder or a service provider, since the market that they are addressing is moving mass to space - which is the same market that Blue Origin and SpaceX are addressing.  The only difference is who owns the vehicles, which is really immaterial when discussing supply and demand.

For instance, if the cost of buying and operating a Skylon does not result in the ability of a service provider to offer a competitive $/kg to orbit price, then no one will buy a Skylon.
The market Skylon is addressing is the market of people who want to offer launch services and that market is substantially larger than just SpaceX and Blue origin and that is not an immaterial difference.

Sorry, but no.  You are not looking at the prime source of the demand.

For instance, no one will buy the Skylon to operate their own transportation business if the Skylon would be the most expensive transportation option.  For example:

The SpaceX current model (i.e. they build and operate their own launchers):
Falcon 9 production costs + SpaceX launch operations costs + SpaceX profit = customer price

The Skylon model that you are suggesting (i.e. the Boeing model):
Skylon production costs + Skylon profit + Operator capital equipment costs (purchase loan, maintenance, etc.) + Operator launch operations costs + Operator profit = customer price

So you can see that builder/operators have an advantage where they skip one layer of profit that otherwise would be added, and that could be enough of a difference to wipe away the competitive advantage of what otherwise would be a lower cost Skylon service.

Until the purchase price and maintenance costs of a Skylon are known, it's hard to argue that the Skylon can beat the price of current competitors.
So what exactly are you imagining the many launch service providers who aren't SpaceX or Blue Origin are going to fly in 2030? The other launch service providers exit today, they'll exist tomorrow and they'll exist in 2030, and when they do they'll have a demand for launch vehicles to market and that demand is what Skylon is built to service.


Five launch providers is substantially fewer that currently exist today servicing a much smaller market but even so assuming two of them are SpaceX and Blue Origin then the other three have to be launching something, so Skylon only has to be the third most cost effective launch vehicle to own a majority of this hypothetical market because, as I've pointed out, it's not competing with falcon and new Glen.

Again, the number "5" was just an example, and not meant to represent reality.

However I would posit that the top three providers winning the most business will have a major profit advantage over the everyone else.  And in case you haven't looked, other than SpaceX and Blue Origin, everyone else in the launch business is state supported in some way, so Skylon would be competing against a lot of deep pockets.  How long could Skylon engage in a price war against nation-states?

I think the Skylon is an interesting concept, and it appeals to my wish that there was such a technology.  But just because it could be technically capable of doing what it's designed to do doesn't mean it could be profitable at doing it.  The two don't always go together.

But as long as someone is willing to put money into the Skylon, I'll keep watching it...
Ahhh... so you've changed your argument from an economic one to a not invented here one. That's an entirely different question. That's like how every national carrier flies indigenously built airliners. Oh wait that doesn't happen.
To be serious this is actually a much more interesting question, in part because it's really more debatable than your original contention but also because our answers are very much coloured by nationality. As an American I'm sure you see having an indigenously built space program as a source of national pride and thus project that onto the rest of the world, but as a Brit I would see having any space program as a source of pride and an economic boon and that perfect is the enemy of good and thus I project that onto the world, and I think more of the world thinks like me than you. But then I would, wouldn't I?
And SpaceX isn't state supported? How much have they been paid over the last decade for developing commercial resupply and commercial crew, how much have they paid NASA for technical aid, how much did they pay NASA for Fastrac? I'm sure REL would love to have that level of non state support.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Paul451 on 11/21/2016 02:49 AM
Your constant repetition of this statement is really starting to make you sound like a troll
Do you want to be treated like a troll?
[...]
A nice piece of innuendo there. You really do sound like you've got a Marketing background.
[...]
Really starting to sound like a troll.

Accusing someone you know as a regular poster of being a troll or a shill is obnoxious and undermines any other argument you make.

If you disagree with someone, disagree with them, don't resort to this kind of passive aggressive crap.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Coastal Ron on 11/21/2016 03:44 AM
So what exactly are you imagining the many launch service providers who aren't SpaceX or Blue Origin are going to fly in 2030? The other launch service providers exit today, they'll exist tomorrow and they'll exist in 2030, and when they do they'll have a demand for launch vehicles to market and that demand is what Skylon is built to service.

I think SpaceX will continue to have a good chunk of the commercial market, and Blue Origin may be planning to go after the commercial market too (not sure we know for sure what their plans are).

Arianespace will continue to win a lot of European business, and Russia and China have state supported launch services which can afford to get into price wars.

So without knowing for sure what the Skylon pricing will be for the most popular payloads (i.e. GEO delivery), it's hard to understand how competitive Skylon can be on day one.  And remember that their competitors can drop their prices to make Skylon look less competitive - which happened to company I worked for with a new service they were working on (I was part of that group).

Skylon, and those buying their own Skylon vehicles, would have to be very well funded in order to succeed in a market like that.  Such market conditions can affect the likelihood that Skylon could find buyers.

It's not an easy market to get into, not as long as so many state-supported launch providers exist - and they are the ones Skylon has to really watch out for.

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Ahhh... so you've changed your argument from an economic one to a not invented here one. That's an entirely different question. That's like how every national carrier flies indigenously built airliners. Oh wait that doesn't happen.

Not sure where you're getting that, since my arguments are purely economic.

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As an American I'm sure you see having an indigenously built space program as a source of national pride and thus project that onto the rest of the world...

Not in this day and age.  Certainly not since SpaceX confirmed that the private sector was more than capable enough to take care of the needs of the U.S. Government.

I see the SLS program as a waste of taxpayer money, since NASA doesn't have enough of a need for an HLV, NASA doesn't have any special experience or expertise in operating a space transportation system (contractors ran the Shuttle program), and NASA's charter specifically calls out for using the private sector when possible.

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...but as a Brit I would see having any space program as a source of pride and an economic boon...

Skylon is not a "space program", it's a transportation system that only goes to LEO.

If it works, then no doubt it will be a source of pride.  As to an "economic boon", ask Airbus about how easy it is to be a transportation vehicle manufacturer.

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...and that perfect is the enemy of good and thus I project that onto the world, and I think more of the world thinks like me than you. But then I would, wouldn't I?

I have no opinion about the technical merits of the Skylon, I've only been talking about the market situation it faces if it finally gets built.  If you feel that's a "glass half-empty" attitude, well I can't change that.

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And SpaceX isn't state supported?

No.  For instance, Arianespace gets direct government reimbursement for every Ariane 5 flight.  SpaceX does not.

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How much have they been paid over the last decade for developing commercial resupply and commercial crew...

They won competitively bid contracts for services.  That would not, in any definition, be "state supported".  Let's not make up definitions when real ones exist.

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how much have they paid NASA for technical aid...

NASA is a national resource, available to any U.S. company to use - if they pay for the services.

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...how much did they pay NASA for Fastrac?

All U.S. companies get access to taxpayer funded research - since all U.S. companies pay taxes (well, except for Trump companies...), all U.S. companies get access to the same taxpayer funded research.  I'm sure you have that in the UK, right?

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I'm sure REL would love to have that level of non state support.

Has the UK ever funded air-breathing engines?  If so you'd think that research would be available for UK companies.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: t43562 on 11/21/2016 04:27 AM

They won competitively bid contracts for services.  That would not, in any definition, be "state supported".  Let's not make up definitions when real ones exist.

Just to nibble at that, was the contract open to non-US companies?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: CameronD on 11/21/2016 05:25 AM

They won competitively bid contracts for services.  That would not, in any definition, be "state supported".  Let's not make up definitions when real ones exist.

Just to nibble at that, was the contract open to non-US companies?

No.. but then there was no requirement for it to be either.  In any open market anywhere on the planet, a buyer, State or Private, is free to set whatever restrictions they feel are important to them.  After all, it's their money.
 
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: t43562 on 11/21/2016 06:31 AM

They won competitively bid contracts for services.  That would not, in any definition, be "state supported".  Let's not make up definitions when real ones exist.

Just to nibble at that, was the contract open to non-US companies?

No.. but then there was no requirement for it to be either.  In any open market anywhere on the planet, a buyer, State or Private, is free to set whatever restrictions they feel are important to them.  After all, it's their money.

That's a red herring. It doesn't matter what the requirements are or are not or whose money it is.  It's a way for the state to support one of it's own industries.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/21/2016 06:34 AM

They won competitively bid contracts for services.  That would not, in any definition, be "state supported".  Let's not make up definitions when real ones exist.

Just to nibble at that, was the contract open to non-US companies?

No.. but then there was no requirement for it to be either.  In any open market anywhere on the planet, a buyer, State or Private, is free to set whatever restrictions they feel are important to them.  After all, it's their money.
Actually it's the taxpayers money since states don't have any money of their own except where they one assets, like coal or gas reserves.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/21/2016 07:04 AM
So without knowing for sure what the Skylon pricing will be for the most popular payloads (i.e. GEO delivery), it's hard to understand how competitive Skylon can be on day one. 
The answer to the question "what is pricing for the most popular payloads" is simple but unintelligible to anyone with an ELV launcher mind set.

It is "Whatever the Skylon operators want it to be."

Unlike the current system of one mfg/one provider Skylon operators would compete with each other. It's likely first buyer would charge market rates for launches as Skylon has a design that's proved by a 400 flight test programme. As more operators come on line that unique sales proposition erodes and operators either start to specialize in certain markets or lower their prices. Meanwhile economies of scale can be expected to lower servicing and support costs.

That is for operators who chose to compete in offering launches outside of their governments, or possibly corporations direct needs. 

Skylon can turn the idea of an affordable "orbital factory" into a reality, without needing an ELV to launch the factory in the first place. As a fully reusable intact abort RLV it give its owner on-demand launch.

People have used various analogies for the space launch market. Let me suggest another.

Current space launch is like a world where personal computers do not exist. Everything is a dumb terminal. All applications are written by the same corporations that supply the terminals. Normal users cannot ever write their own programs. All data is of course accessible to corporations that operate the system and the governments of the jurisdictions they operate in.

Now someone makes a PC. It runs whatever software you load (or write) on it. When you want it and data that's on it stays on it.  IOW it gives it's users control of their applications and their data (and if you think that's a mad scenario what is Office365)?

Nothing that uses the sole mfg / sole operator model will ever give payload owners that level of control. You launch when Arianespace, or SX, or ULA say you can launch.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: oddbodd on 11/21/2016 08:18 AM
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I'm sure REL would love to have that level of non state support.

Has the UK ever funded air-breathing engines?  If so you'd think that research would be available for UK companies.

Well actually, yes they have, and yes you would think so... :) Alan Bond worked on the RB545/HOTOL which was an air breathing SSTO reusable space plane launch system, which is the spiritual parent of SABRE/Skylon. It was funded by the UK government till they lost interest/patience (the design had massive CoG issues because the engines were at the rear). Then the typically short-sighted UK government killed funding and slapped it under the official secrets act, leaving the idea to rot. So Bond, Scott-Scott and Varvill had to go away and come up with another design that would not make them fall foul of the act. RB545 may have been declassified by now (http://sounds.bl.uk/related-content/TRANSCRIPTS/021T-C1379X0005XX-0000A0.pdf (http://sounds.bl.uk/related-content/TRANSCRIPTS/021T-C1379X0005XX-0000A0.pdf) and seach for classified), but the information is probably not of use with the evolution of the SABRE along its own trajectory (pun intended).
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: lkm on 11/21/2016 12:29 PM
So what exactly are you imagining the many launch service providers who aren't SpaceX or Blue Origin are going to fly in 2030? The other launch service providers exit today, they'll exist tomorrow and they'll exist in 2030, and when they do they'll have a demand for launch vehicles to market and that demand is what Skylon is built to service.

I think SpaceX will continue to have a good chunk of the commercial market, and Blue Origin may be planning to go after the commercial market too (not sure we know for sure what their plans are).

Arianespace will continue to win a lot of European business, and Russia and China have state supported launch services which can afford to get into price wars.

So without knowing for sure what the Skylon pricing will be for the most popular payloads (i.e. GEO delivery), it's hard to understand how competitive Skylon can be on day one.  And remember that their competitors can drop their prices to make Skylon look less competitive - which happened to company I worked for with a new service they were working on (I was part of that group).

Skylon, and those buying their own Skylon vehicles, would have to be very well funded in order to succeed in a market like that.  Such market conditions can affect the likelihood that Skylon could find buyers.

It's not an easy market to get into, not as long as so many state-supported launch providers exist - and they are the ones Skylon has to really watch out for.
So you've singularly failed to answer the actual question, so I'm going to have to guess at your implied answers.
You think state backed launch service providers will stick with indigenously developed launchers even if a reusable SSTO was for sale for nationalistic reasons.
In reality if Skylon actually gets built it will be dependent upon Arianespace being a development and launch partner because Skylon will be built by much the same contractors that currently build Ariane, the China Aerospace Science and Technology Corporation will buy some just to take apart and reverse engineer and the Russians will still have no money and be under a trade embargo.
Ahhh... so you've changed your argument from an economic one to a not invented here one. That's an entirely different question. That's like how every national carrier flies indigenously built airliners. Oh wait that doesn't happen.

Not sure where you're getting that, since my arguments are purely economic.
If you are arguing that state backed launch providers won't buy Skylon because it's not an indigenously developed launcher then that is a political argument.

As an American I'm sure you see having an indigenously built space program as a source of national pride and thus project that onto the rest of the world...

Not in this day and age.  Certainly not since SpaceX confirmed that the private sector was more than capable enough to take care of the needs of the U.S. Government.

I see the SLS program as a waste of taxpayer money, since NASA doesn't have enough of a need for an HLV, NASA doesn't have any special experience or expertise in operating a space transportation system (contractors ran the Shuttle program), and NASA's charter specifically calls out for using the private sector when possible.

Quote
...but as a Brit I would see having any space program as a source of pride and an economic boon...

Skylon is not a "space program", it's a transportation system that only goes to LEO.

If it works, then no doubt it will be a source of pride.  As to an "economic boon", ask Airbus about how easy it is to be a transportation vehicle manufacturer.

Quote
...and that perfect is the enemy of good and thus I project that onto the world, and I think more of the world thinks like me than you. But then I would, wouldn't I?

I have no opinion about the technical merits of the Skylon, I've only been talking about the market situation it faces if it finally gets built.  If you feel that's a "glass half-empty" attitude, well I can't change that.
Misconstrued word choice, two nations divided by a language.
I didn't mean Space Program in that narrow national sense but in the sense of having a space Industry that puts things in orbit and gets things done there, public/private is irrelevant to what I meant.
 Thus when I talk about having a space industry vis à via an indigenously built one I'm implicitly not talking about developing Skylon I'm saying any space company choosing to operate launches from here would be good and produce economic gains for the national economy, as studies of Skylon show it would, and that as such the "perfect", having an indigenously built launch vehicle, is the enemy of "good", having a space launch industry at all. As an American you already have the "perfect" and that colours your view of what other people want.
If you are saying state launch providers won't be interested in Skylon because it's not indigenous then I'm  saying that if you start from not having much then "good" can look pretty good.
And SpaceX isn't state supported?

No.  For instance, Arianespace gets direct government reimbursement for every Ariane 5 flight.  SpaceX does not.
Did I say Arianespace isn't state supported?
How much have they been paid over the last decade for developing commercial resupply and commercial crew...

They won competitively bid contracts for services.  That would not, in any definition, be "state supported".  Let's not make up definitions when real ones exist.
The service contracts explicitly exist in an attempt to develop private space companies , they are exactly the sort of contract that the EU complained to the WTO regarding Boeing state aid. SpaceX was paid by NASA to develop hardware that SpaceX wanted to develop anyway and NASA just funded the development.
how much have they paid NASA for technical aid...

NASA is a national resource, available to any U.S. company to use - if they pay for the services.
There's no requirement in a Space Act Agreement that NASA is reimbursed for their services. Given SpaceX's activities their SAA's were likely to be nonreimbursable  agreements.

...how much did they pay NASA for Fastrac?

All U.S. companies get access to taxpayer funded research - since all U.S. companies pay taxes (well, except for Trump companies...), all U.S. companies get access to the same taxpayer funded research.  I'm sure you have that in the UK, right?
And that's state support. The state paid for something and then gave it away free to SpaceX.
I'm sure REL would love to have that level of non state support.

Has the UK ever funded air-breathing engines?  If so you'd think that research would be available for UK companies.
The UK has invested $90million in REL, which was held up for two years while it was evaluated over whether it was illegal state aid, while NASA has spent $3144.6million on SpaceX over the same period, or nearly 35 times more. As I said,  I'm sure REL would love to have that level of non state support.

I think you might be under the illusion that state support is bad, it's not. Pretending that it doesn't exist, that a company or person just manfully carved their existence out nothing is.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: DM27 on 11/21/2016 02:28 PM
I think this is very encouraging for REL:
https://www.theengineer.co.uk/where-winners-can-emerge-and-grow/

Hopefully it/something similar to this initiative can be delivered.

I can see this (if it ever happens) manifesting itself in UK defence projects and I think that would be the best outcome for REL. I noticed a few months ago that the RAF launched a competition for 16-18 year olds to "design" a SABRE engine based long distance transport aircraft. if the UK can fund it's own Small launcher craft through the UKSA (MPs have been determined to create a larger scale national space programme) and an RAF funded large military transport craft in the mould of the 2 platforms on RELs new website, that would be a great strategy. the manufacturer, most likely a BAE (and possibly an additional partner) could simply commercialise the platforms for a fraction of the cost that developing the commercial platforms from scratch would cost.

Also, point 5 in the extremely well written article below would seem to suggest that May is thinking along these lines too:

http://www.politico.eu/article/5-takeaways-from-theresa-mays-speech-to-business-leaders/

As a Brit very excited about RELs tech, I really hope that is how it pans out.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: CameronD on 11/21/2016 08:29 PM

They won competitively bid contracts for services.  That would not, in any definition, be "state supported".  Let's not make up definitions when real ones exist.

Just to nibble at that, was the contract open to non-US companies?

No.. but then there was no requirement for it to be either.  In any open market anywhere on the planet, a buyer, State or Private, is free to set whatever restrictions they feel are important to them.  After all, it's their money.

That's a red herring. It doesn't matter what the requirements are or are not or whose money it is.  It's a way for the state to support one of it's own industries.
..should they choose to do so. 

Again, since the decision-makers in question have been empowered by the people of that state to make decisions in the best interests of that state then they're free to set whatever restrictions they feel are important to them.

In some cases that might be to invite tenders from outside the state... in other cases, maybe not. :)

Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 11/21/2016 08:30 PM
Some general comments and replies:
Oddball wrote:
Quote
I understand what you're saying, and agree with much. What I'm trying to say (in a cack-handed way) is that the current methods are too slow, inflexible and prone to exploding to ever end up with a significant human space presence. Even Space X with a partially reusable rocket will take weeks (if not months) to reintegrate for a second launch.

Actually you DON'T understand what I'm getting at and for the most part neither do most people on here but really that's ok :)

Our "current methods" are in fact easily and fully capable of handling a much higher rate of traffic and payload-to-orbit than we currently have. Inflexible? Far from it actually as we've moved to a very flexible and rather 'containerized' mode of operations and did so in space launch LONG before most terrestrial transportation did so despite the rather obvious operational and economic incentives to do so. "Prone to exploding"? More to the point they are in fact no more 'prone' to not delivering cargo to the destination as most other transport systems historically. We don't generally put life jackets or parachutes on cargo containers "just in case" the ship goes down of the airplane crashes either.

Turn around time? You suggest some where around "sub-week" as a time frame, well rest assured that it could be done if there was enough traffic. I don't expect Elon to get his 'hours' turn around time it's just not a realistic goal for a TSTO that started life as an ELV. Maybe once he gets a more integrated design with both stages being fully reusable he'll get down to a day or two but I suspect it would take a much more 'from-the-ground-up' design to reach that on an operational basis. Of course that's "per-vehicle" which really doesn't matter as much as you might think.

See you normally don't need more than 8-12 hours tops to 'refurbish' a pad to the point where you can begin stacking another LV on it and that is actually far higher a pace than any current 'requirement' can drive. Aircraft at a busy airport take off in less than 5 minute intervals, ships leave port dozens at a time, yadda, yadda, and it is simply NOT a factor when it comes to space launch. Those systems have had hundreds to thousands of years to reach that point AND they have always had an extensive PRE-EXISTING system of destinations and cargos in which to tap to provide the incentive to reach those levels.

Space does NOT have that. At. All.
I've heard this before:
Quote
It's a vicious circle: no destinations, no market; no market, no demand; no demand, no destinations. Until someone/something comes along to break that, it feels like we will be forever stuck in LEO for manned missions, GEO for communications, and the occasional splurge for scientific robotic observation BEO. So those of us dreaming of Moon/Mars colonies, orbital space stations, or research bases on Europa, will just keep on dreaming.

No one can 'break' a circle that in fact does NOT exist. Note that there IS a "demand" and a "market" in existence, the fact that it is not as large or extensive as some would like and that it does not in fact 'service' a market that does not exist but which some want to exist is totally beside the point.

The fallacy here is "we" need to "make" destinations and markets for reusable SSTO, (and yes that's the main argument FOR SSTO by the way) by building an extensive LEO orbital infrastructure for them to service.

It's a fallacy because that's not how transportation systems work either economically or in reality. Transportation gets cheaper servicing a market not by creating it which is what most people get wrong. Airplanes didn't 'create' any market but became economical in servicing existing markets in less time than other forms of transportation. (Time is money after all :) ) There is an existing 'market' and economy that expendable launch vehicles in fact DO service at this moment and do so economically and fairly regularly. Rather obviously a reusable launch vehicle that can service that same market should be able to do so more economically. Not so obviously does this apply to SSTO vehicles mostly for the fact that MOST SSTO concepts have never managed to reach a comparable operational payload to an ELV or multistage reusable vehicle. Note I wrote "operational payload" rather than just 'payload' because in fact while Skylon is an SSTO it does in fact require a second stage to allow getting the 'payload' to the most in-demand destinations despite that fact. But at least REL was realistic about that and therefore designed the Skylon with more capacity than the average SSTO concept.

Are there any other SSTO concepts out there in development? No, for the most part they have been found to be lacking in both economy and utility as has been pointed out. (Note though; in fact neither Musk or Beezos did much 'due-diligence' work on anything OTHER than the concepts they went forward with. Neither considered for example any type of air-breathing or horizontal take off/landing concepts as they did not consider them 'viable' BEFORE they began design trade studies. They already had made up their minds on what would and would not be included in the 'trades' of the designs) Pure-rocket powered VTOL SSTO's have in fact been suggested and pushed for decades but none have reached even prototype flight status. (No the DC-X was NOT a flight prototype but a very limited VTOL demonstrator) And for good reason as they suffer from a lack of payload in comparison to any multistage design and normally require much more complex and expensive technology to achieve.

To consider our current situation to be 'game over' is unrealistic to me as we do in fact have a number of possible game changers in the pipeline of which one is Skylon. I do not see any 'window of opportunity' which is closing on the Skylon concept as, rather obviously, any successful fully reusable TSTO design technology would only benefit the development of Skylon and any Skylon/SABRE development can't but help towards technology that can be used for multistage designs as well.

And lastly on which is the better 'strategy' of builder/operator or builder to owner/operator for the most part the differing sides seem bound and determined to ignore history and reality to make their point :)
The latter ALWAYS takes over from the former once a certain level of traffic is reached as the builders can no longer afford to do both they inevitably form partnerships/consortiums to "buy" the vehicles and then own and operate them while they then concentrate on design and manufacture of new and improved vehicles. REL is simply assuming that the traffic levels will hit the levels that both SpaceX and BO are PLANNING on reaching and planning accordingly while SpaceX and BO are currently not looking to that point. Yet.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 11/21/2016 08:37 PM
Oh and before I forget, the ISS is really an example of what you WANT yet you argue like it's a 'bad' thing. After all we COULD use a Saturn-V or SLS to put up the whole thing in ONE flight and then send ONE other flight to carry all the supplies it will need for it's life time which gets you TWO (2) flights of a massively expensive system that you won't need/can't afford to do again for the life time of the station. Or you can fly dozens to hundreds of flights over the same lifetime with a more economic system.

In theory you can put up a lot of other payloads that go far beyond LEO with the latter than the former, (note the "s" there) with much greater flexibility and utility. But it greatly depends on what your (or whoever's paying the bills) actual goal is now doesn't it? :)

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Jim on 11/21/2016 08:56 PM

But after a 400 flight test programme (which is factored into the budget) they will know very well.

Which could take a decade.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: francesco nicoli on 11/21/2016 09:13 PM

They won competitively bid contracts for services.  That would not, in any definition, be "state supported".  Let's not make up definitions when real ones exist.

Just to nibble at that, was the contract open to non-US companies?

No.. but then there was no requirement for it to be either.  In any open market anywhere on the planet, a buyer, State or Private, is free to set whatever restrictions they feel are important to them.  After all, it's their money.

That's a red herring. It doesn't matter what the requirements are or are not or whose money it is.  It's a way for the state to support one of it's own industries.

legally, it depends. I am not sure about antitrust law in the US. But in Europe, it depends on a case by case decision of the judge.
Generally, you cannot restrict too much to whom the competition is open: anyone from the internal market (EU in EU, US in US) is allowed to participate (or get state aid, in other cases). In other words, the contract competition (or the state aid) should be non discriminating on nationality..
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: oddbodd on 11/21/2016 09:44 PM
Some general comments and replies:
Oddball wrote:
Quote
I understand what you're saying, and agree with much. What I'm trying to say (in a cack-handed way) is that the current methods are too slow, inflexible and prone to exploding to ever end up with a significant human space presence. Even Space X with a partially reusable rocket will take weeks (if not months) to reintegrate for a second launch.

Our "current methods" are in fact easily and fully capable of handling a much higher rate of traffic and payload-to-orbit than we currently have. Inflexible? Far from it actually as we've moved to a very flexible and rather 'containerized' mode of operations and did so in space launch LONG before most terrestrial transportation did so despite the rather obvious operational and economic incentives to do so. "Prone to exploding"? More to the point they are in fact no more 'prone' to not delivering cargo to the destination as most other transport systems historically. We don't generally put life jackets or parachutes on cargo containers "just in case" the ship goes down of the airplane crashes either.

Just to nit-pick one thing. I did specify that the exploding thing was a hindrance to human presence, not cargo. Annual rocket failures seem to be bumping around in the 5% area, so 1 in 20 flights frequently has a fiery, premature end. Go to Heathrow and tell all those business and tourist travelers that every flight has a 1 in 20 chance of catastrophic failure, killing everyone aboard. Excluding the mentally ill, suicidal and people under extreme duress, I'll take a wild stab in the dark that zero people would choose to fly. Even if they were, there'd be no pilots or cabin staff willing to roll that D20-of-death every time they did their job. Hopefully the abort system in the SpaceX Dragon module will at least mean that it's just very expensive, instead of tragic.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: oddbodd on 11/21/2016 10:09 PM
Oh and before I forget, the ISS is really an example of what you WANT yet you argue like it's a 'bad' thing. After all we COULD use a Saturn-V or SLS to put up the whole thing in ONE flight and then send ONE other flight to carry all the supplies it will need for it's life time which gets you TWO (2) flights of a massively expensive system that you won't need/can't afford to do again for the life time of the station. Or you can fly dozens to hundreds of flights over the same lifetime with a more economic system.

In theory you can put up a lot of other payloads that go far beyond LEO with the latter than the former, (note the "s" there) with much greater flexibility and utility. But it greatly depends on what your (or whoever's paying the bills) actual goal is now doesn't it? :)

Randy

I don't think I criticised the end result. Just the cost, the time it took to construct, and the fact we don't/can't use it as a staging point. The ISS mass is supposed to be 420 metric tonnes. The Saturn V could lift 140 metric tonnes, but only half way to the height the ISS is currently stationed. I expect that mass figure to be lower due to the inclination, and the extra height required. So just on mass it's going to be 4 or more flights + 1 for supplies. I don't have a sense of how many components could be launched on a single rocket though, as there are no wikipedia details of the Saturn V's payload dimensions.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Coastal Ron on 11/21/2016 11:46 PM
[So you've singularly failed to answer the actual question, so I'm going to have to guess at your implied answers.

Lots of issues here, so I'm not knowingly not answering whatever question you thought was the actual question.  Especially since I was the one that started the conversation...

Quote
You think state backed launch service providers will stick with indigenously developed launchers even if a reusable SSTO was for sale for nationalistic reasons.

Yep.

Quote
...the China Aerospace Science and Technology Corporation will buy some just to take apart and reverse engineer...

Nah.  They'll just steal the designs and documents, which is far better than trying to reverse engineer something.

Quote
Misconstrued word choice, two nations divided by a language.

Happens even within the same country, so no worries.

Quote
I didn't mean Space Program in that narrow national sense but in the sense of having a space Industry that puts things in orbit and gets things done there, public/private is irrelevant to what I meant.

A country can have a wish, but just because they wish it to be so doesn't mean it will.  Coming up with a successful product or service takes a lot of work, and to a degree, luck.

Quote
Thus when I talk about having a space industry vis à via an indigenously built one I'm implicitly not talking about developing Skylon I'm saying any space company choosing to operate launches from here would be good and produce economic gains for the national economy...

Building Skylon would provide an economic benefit, wouldn't it?  Because once they sell a Skylon, I would imagine chances are it won't launch from the UK, so the only economic benefit would be from the building and selling of Skylon vehicles.  That would be my observation.

Quote
as studies of Skylon show it would

Uh, anyone could come up with a study to "prove" something will happen.  However no one really knows until it becomes reality.  Just saying...


Quote
And that's state support. The state paid for something and then gave it away free to SpaceX.

No, U.S. Taxpayers (individuals and companies) paid for it.  And by law, NASA must share their research with U.S. companies.

Quote
The UK has invested $90million in REL, which was held up for two years while it was evaluated over whether it was illegal state aid, while NASA has spent $3144.6million on SpaceX over the same period...

NASA paid SpaceX to perform services for NASA.  So that is not the same as what you are describing.  Apples & oranges.

Quote
I think you might be under the illusion that state support is bad...

No.  I just like to keep the lines clear on what is state aid and what is payment for services rendered.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Star One on 11/21/2016 11:59 PM
I think this is very encouraging for REL:
https://www.theengineer.co.uk/where-winners-can-emerge-and-grow/

Hopefully it/something similar to this initiative can be delivered.

I can see this (if it ever happens) manifesting itself in UK defence projects and I think that would be the best outcome for REL. I noticed a few months ago that the RAF launched a competition for 16-18 year olds to "design" a SABRE engine based long distance transport aircraft. if the UK can fund it's own Small launcher craft through the UKSA (MPs have been determined to create a larger scale national space programme) and an RAF funded large military transport craft in the mould of the 2 platforms on RELs new website, that would be a great strategy. the manufacturer, most likely a BAE (and possibly an additional partner) could simply commercialise the platforms for a fraction of the cost that developing the commercial platforms from scratch would cost.

Also, point 5 in the extremely well written article below would seem to suggest that May is thinking along these lines too:

http://www.politico.eu/article/5-takeaways-from-theresa-mays-speech-to-business-leaders/

As a Brit very excited about RELs tech, I really hope that is how it pans out.
Well you're going to be disappointed then with the predicted huge budget shortfall which I expect we'll hear more of at the autumn statement this just isn't going to happen.

After all the argument could be made as to why should the British taxpayer fund this when hopefully BAE will be able to get the USAF sufficiently interested in the technology that they will pick up the tab to develop it further.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: t43562 on 11/22/2016 06:49 AM

Quote
I think you might be under the illusion that state support is bad...

No.  I just like to keep the lines clear on what is state aid and what is payment for services rendered.

I think you mean keeping the line unclear.  However you weasel around it, the state is helping an industrial sector to compete against foreigners - for whatever reasons and with whatever justification. Whether or not they have a right to is completely beside the point - I don't care about that and I can't see anyone else here who does.  It only matters in as much as it seems improbable at this time that one might survive without such arrangements.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: ChrisWilson68 on 11/22/2016 07:48 AM

Quote
I think you might be under the illusion that state support is bad...

No.  I just like to keep the lines clear on what is state aid and what is payment for services rendered.

I think you mean keeping the line unclear.  However you weasel around it, the state is helping an industrial sector to compete against foreigners - for whatever reasons and with whatever justification. Whether or not they have a right to is completely beside the point - I don't care about that and I can't see anyone else here who does.  It only matters in as much as it seems improbable at this time that one might survive without such arrangements.

No, Ron is right, there's a very clear line between payment for goods and services and payment that is not in exchange for goods and services, or above the price the government would have to pay for those goods and services from another source.  There's no weaselling involved.  It's the distinction that makes the most sense to make.

It's the difference between business and charity.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/22/2016 08:31 AM
Nah.  They'll just steal the designs and documents, which is far better than trying to reverse engineer something.
They might like to study how well that worked out for the Russian Tu144 programme.
Stealing plans does not necessarily mean you understand what you're looking at.  :(
Quote
Building Skylon would provide an economic benefit, wouldn't it?  Because once they sell a Skylon, I would imagine chances are it won't launch from the UK, so the only economic benefit would be from the building and selling of Skylon vehicles.  That would be my observation.
There are some orbits that are quite accessible from the UK. Skylon servicing would probably be based there as well.
Quote
Uh, anyone could come up with a study to "prove" something will happen.  However no one really knows until it becomes reality.  Just saying...
Depends on the methodology and the transparency of that methodology.

Read enough studies and you can usually see where someone has "cooked" the results, along with certain consultancies being more prone to it than others.    :(
No one can 'break' a circle that in fact does NOT exist. Note that there IS a "demand" and a "market" in existence, the fact that it is not as large or extensive as some would like and that it does not in fact 'service' a market that does not exist but which some want to exist is totally beside the point.
But it does exist, which Skylon can service.
Quote
The fallacy here is "we" need to "make" destinations and markets for reusable SSTO, (and yes that's the main argument FOR SSTO by the way) by building an extensive LEO orbital infrastructure for them to service.
And it's one that REL is aware of and does not subscribe. Enable yes, require, no.
Quote
Not so obviously does this apply to SSTO vehicles mostly for the fact that MOST SSTO concepts have never managed to reach a comparable operational payload to an ELV or multistage reusable vehicle. Note I wrote "operational payload" rather than just 'payload' because in fact while Skylon is an SSTO it does in fact require a second stage to allow getting the 'payload' to the most in-demand destinations despite that fact. But at least REL was realistic about that and therefore designed the Skylon with more capacity than the average SSTO concept.
But note Skylon can support an "all electric" design by starting outside the Van Allan belts.
Quote

Are there any other SSTO concepts out there in development? No, for the most part they have been found to be lacking in both economy and utility as has been pointed out.

(Note though; in fact neither Musk or Beezos did much 'due-diligence' work on anything OTHER than the concepts they went forward with. Neither considered for example any type of air-breathing or horizontal take off/landing concepts as they did not consider them 'viable' BEFORE they began design trade studies. They already had made up their minds on what would and would not be included in the 'trades' of the designs) Pure-rocket powered VTOL SSTO's have in fact been suggested and pushed for decades but none have reached even prototype flight status. (No the DC-X was NOT a flight prototype but a very limited VTOL demonstrator) And for good reason as they suffer from a lack of payload in comparison to any multistage design and normally require much more complex and expensive technology to achieve.
Something I'd like people to keep in mind.  Let's just repeat that for people who think either of them looked at Skylon:

neither Musk or Beezos did much 'due-diligence' work on anything OTHER than the concepts they went forward with.
Quote
And lastly on which is the better 'strategy' of builder/operator or builder to owner/operator for the most part the differing sides seem bound and determined to ignore history and reality to make their point :)
The latter ALWAYS takes over from the former once a certain level of traffic is reached as the builders can no longer afford to do both they inevitably form partnerships/consortiums to "buy" the vehicles and then own and operate them while they then concentrate on design and manufacture of new and improved vehicles. REL is simply assuming that the traffic levels will hit the levels that both SpaceX and BO are PLANNING on reaching and planning accordingly while SpaceX and BO are currently not looking to that point. Yet.
Careful about "historical inevitability"   :)

While the market should transition to separate mfg and operators note that US market, where Boeing/TWA was probably broken up before this stage. IOW government intervention accelerated the split. 

But any kind of VTO rocket is a potential ICBM so the odds on bet is govt intervention will be negative. I don't see ULA, SX or Blue setting up a Guianna branch any time soon, do you?

Skylon does not look like an ICBM. It does not fly like an ICBM. It's very difficult to modify into an ICBM or an ICBM delivery vehicle and if you have the skills to do so you can probably make an ICBM yourself, so why bother?

Only the REL business model (and something like it's architecture) have a chance of getting away, of unifying the market by giving the economies of scale of a large market IE every payload on the planet but giving individual countries (or even corporations) the security of delivery of their payload.

Telecos talk about the "last mile" of cable being the most expensive because there's so much of it to maintain and the individual payoff is so small but in space launch it's the first 100-200Km that's the major PITA. Skylon take that away in a way that no nation based rocket programme (and that includes Blue or SX) can ever do.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 11/22/2016 03:26 PM
Just to nit-pick one thing. I did specify that the exploding thing was a hindrance to human presence, not cargo. Annual rocket failures seem to be bumping around in the 5% area, so 1 in 20 flights frequently has a fiery, premature end. Go to Heathrow and tell all those business and tourist travelers that every flight has a 1 in 20 chance of catastrophic failure, killing everyone aboard. Excluding the mentally ill, suicidal and people under extreme duress, I'll take a wild stab in the dark that zero people would choose to fly. Even if they were, there'd be no pilots or cabin staff willing to roll that D20-of-death every time they did their job. Hopefully the abort system in the SpaceX Dragon module will at least mean that it's just very expensive, instead of tragic.

Closer to 4% really (86 launches/5 failures in 2015, 72/1 this year) but the whole point was that humans ARE treated differently than cargo as in most transportation systems. Transport systems make a specific point to assure travelers that they have little chance of dying even in the worst case and given a "better than even" chance to survive an accident most people will willingly keep travelling. You would also be lying, (and liable :) ) if you told anyone that was their 'chances' in a launch accident since it's quite obvious that there are systems in place to keep the PEOPLE alive in the case of a failure. (None of the travelers at Heathrow have that option though and it does not seem to effect travel statistics)

According to many on this site if given the opportunity they would volunteer to ride a Dragon-1 WITHOUT an abort system come what may so I'd watch out throwing around the accusations of only the "mentally ill, suicidal and people under extreme duress" being willing to take their chances. If you've been over to the SpaceX ITS threads you'll note one discussing the lack of an abort system on the ITS which does in fact 'bother' some people but as noted it is in fact similar to current aircraft in that regard. If you are on an airplane that crashes you have no way of escaping and have to ride the plane to whatever the end point is, similarly if you were a passenger on Skylon you and the airframe are 'wedded' in fates. SSTO tends to assume a higher margin for 'safety' than a multistage design but in fact there is no basis for that assumption other than the "fact" that over their evolution most OTHER transport systems are 'technically' "single-stage" vehicles that have become much safer over time. Note that is OVER TIME during which they continually got safer and more efficient as they evolved.

My point is and was that the "chances" of dying being launched in a current rocket are no worse than most other transportation accidents SPECIFICALLY because passenger transport is currently considered and addressed as a safety issue. This is only "different" in designs that assume, with no data to back that up, that the vehicle is much 'safer' because it emulates a CURRENTLY "more safe" evolved design of another form of transportation. AKA it's "safer" because it resembles and airplane which is rather silly because what it looks like has almost nothing to do with what it actually DOES over the majority of it's flight and over that flight conditions change radically from anything any "airplane" does except the very beginning and very end.

Skylon is still a LAUNCH VEHICLE with all that implies.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 11/22/2016 04:02 PM
I don't think I criticised the end result. Just the cost, the time it took to construct, and the fact we don't/can't use it as a staging point.

That pretty much IS criticizing the "end result" you realize? :) And frankly all those factors were part of the "process" of the design and construction which were all based on the authorization and political factors. Specifically it was never meant to be, (and frankly was authorized as not being usable as) a staging point as NASA was never authorized to do anything beyond LEO at the time. (Still have not been authorized to do so by Congress I might add)

In fact it COULD be used for staging beyond LEO work though it isn't optimal for such purposes. The main problem is the ISS has specifically been made a "national laboratory" by act of Congress which means it's "research" mission is and has priority over any other use and it already has major issues due to crew movement and thruster action that impedes the microgravity studies.

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The ISS mass is supposed to be 420 metric tonnes. The Saturn V could lift 140 metric tonnes, but only half way to the height the ISS is currently stationed. I expect that mass figure to be lower due to the inclination, and the extra height required. So just on mass it's going to be 4 or more flights + 1 for supplies. I don't have a sense of how many components could be launched on a single rocket though, as there are no wikipedia details of the Saturn V's payload dimensions.

75 to about 161 tonnes depending on the model, you could 'hammerhead' the payload but a general figure is 10.06m/33ft in diameter and somewhere between 14 to 30m (45-98ft) in length depending on mass. (http://www.astronautix.com/s/saturnv.html) The problem is it wouldn't be any more 'economic' or usable even with far less flights, more especially with far less flights :)

It might have cost less if the launches had been done commercially, it almost certainly would have cost less if it had a commercial purpose and wasn't restricted to the needs of allowing Russian participation by inclination but you have to consider that having Russian access might actually have commercial applications. But that all depends on there being 'commercial' applications for a space station which at this point-in-time is not as clear as it might be. (Frankly we need to do some major research into microgravity industrial applications but, again, this is currently something that Congress has specifically NOT authorized as part of the ISS mission) But to build it with commercial launchers would have taken much longer so you have to make some choices which will lead to both the type and architecture of the station being built.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: lkm on 11/22/2016 05:44 PM
[So you've singularly failed to answer the actual question, so I'm going to have to guess at your implied answers.

Lots of issues here, so I'm not knowingly not answering whatever question you thought was the actual question.  Especially since I was the one that started the conversation...
You quoted me asking a simple direct question and then replied with 200 words failing to answer it.
You think state backed launch service providers will stick with indigenously developed launchers even if a reusable SSTO was for sale for nationalistic reasons.

Yep.
And do also accept that's a political argument?

Thus when I talk about having a space industry vis à via an indigenously built one I'm implicitly not talking about developing Skylon I'm saying any space company choosing to operate launches from here would be good and produce economic gains for the national economy...

Building Skylon would provide an economic benefit, wouldn't it?  Because once they sell a Skylon, I would imagine chances are it won't launch from the UK, so the only economic benefit would be from the building and selling of Skylon vehicles.  That would be my observation.

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as studies of Skylon show it would

Uh, anyone could come up with a study to "prove" something will happen.  However no one really knows until it becomes reality.  Just saying...
Ok, so to be clear, that's the policy of the UK government, UKSpace, the U.K. space industry body, and multiple studies carried out by London Economics upon which these policies are based.
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SABRE could potentially create 21,000 high value engineering and manufacturing jobs and maximise the UK’s access to a conservatively estimated £13.8bn launcher market over the next thirty years as well as provide economic benefits from spillovers. London Economics estimated the socio‐economic impacts for Europe of a SKYLON‐based European Launch Service Operator at €20‐24bn in Net Present Value terms (2014 prices, nominally 30 years)


And that's state support. The state paid for something and then gave it away free to SpaceX.

No, U.S. Taxpayers (individuals and companies) paid for it.  And by law, NASA must share their research with U.S. companies.
Ah but really it was the taxpayer's employers who paid for it, no actually it was the consumers of those businesses who employed those taxpayers who paid for it, no it must have been the employers of those customers of those businesses who employed those taxpayers who paid for it.
 It's turtles all the way down!

The UK has invested $90million in REL, which was held up for two years while it was evaluated over whether it was illegal state aid, while NASA has spent $3144.6million on SpaceX over the same period...

NASA paid SpaceX to perform services for NASA.  So that is not the same as what you are describing.  Apples & oranges.

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I think you might be under the illusion that state support is bad...

No.  I just like to keep the lines clear on what is state aid and what is payment for services rendered.
Ah. State Support is not State Aid. State aid has a clearly defined legal meaning, it's a small illegal subset of state support. I've been talking about state support.
You'll note my example of UK state support was explicitly ruled not state aid.
State support is everything a state can do, either through regulation, legislation, infrastructure spending, investment or procurement that will encourage a desirable outcome for any particular business, industrial sector or demographic and the state itself. It's the tool of an active state with an industrial policy.
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In November 2005, Dr. Griffin articulated that:
With the advent of the ISS, there will exist for the first time a strong, identifiable market for "routine" transportation service to and from LEO, and that this will be only the first step in what will be a huge opportunity for truly commercial space enterprise. We believe that when we engage the engine of competition, these services will be provided in a more cost-effective fashion than when the government has to do it.[7]
The state wanted to support commercial space enterprise and created an policy to do that.


Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Lars-J on 11/22/2016 06:39 PM
Something I'd like people to keep in mind.  Let's just repeat that for people who think either of them looked at Skylon:

neither Musk or Beezos did much 'due-diligence' work on anything OTHER than the concepts they went forward with.

 ::)  Repeating such an assertion does not make it any more true.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: knowles2 on 11/22/2016 07:00 PM
I'm bit confuse by Theresa May promises actually because the current R&D budget is 4.6 billion and been frozen since 2011, so is she promising this to be increase to 6.6 billion by 2020?

An given how this government "extra" money often end up coming from a different pot of money in the same department, I'm not sure I believe this will actually be new money.

An how much of this extra money is going to be use just cover things that have been delayed since 2011 because of the frozen budgets or deal with a backlog of replacing and repairing equipment and labs, pay rises.

An potentially how much of money will simply be in forms which can only be access if you already got an investor, tax reductions, tax credits and allowances.

This "not picking" winner mantra of the government really doesn't help get large, medium or small scale projects off the ground, in fact it often delays projects for months if not years why people, companies search for private investors. It only by government or ideal a team of scientist and engineers picking winners will we really transform the UK lack of success in getting projects out of the lab into the wild creating jobs.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: knowles2 on 11/22/2016 07:36 PM
I think this is very encouraging for REL:
https://www.theengineer.co.uk/where-winners-can-emerge-and-grow/

Hopefully it/something similar to this initiative can be delivered.

I can see this (if it ever happens) manifesting itself in UK defence projects and I think that would be the best outcome for REL. I noticed a few months ago that the RAF launched a competition for 16-18 year olds to "design" a SABRE engine based long distance transport aircraft. if the UK can fund it's own Small launcher craft through the UKSA (MPs have been determined to create a larger scale national space programme) and an RAF funded large military transport craft in the mould of the 2 platforms on RELs new website, that would be a great strategy. the manufacturer, most likely a BAE (and possibly an additional partner) could simply commercialise the platforms for a fraction of the cost that developing the commercial platforms from scratch would cost.

Also, point 5 in the extremely well written article below would seem to suggest that May is thinking along these lines too:

http://www.politico.eu/article/5-takeaways-from-theresa-mays-speech-to-business-leaders/

As a Brit very excited about RELs tech, I really hope that is how it pans out.
Well you're going to be disappointed then with the predicted huge budget shortfall which I expect we'll hear more of at the autumn statement this just isn't going to happen.

After all the argument could be made as to why should the British taxpayer fund this when hopefully BAE will be able to get the USAF sufficiently interested in the technology that they will pick up the tab to develop it further.
BAE will only fund

Because USAF beholden by laws passed by congress will insist manufacturing, R&D and testing takes place in the US so the UK will lose out on jobs and potentially tax revenue. An that will be even more so the case under Trump presidency.

Budget shortfalls is going to have less meaning than ever before because the only way the UK is going to survive Brexit is substantial investments in programs like Skylon and other scientific research and development projects, large, medium and small and infrastructure, and I think Hammon have or will realise that the time of cuts for the vast majority of governments departments is well and truly over, he is going to have demands for money coming from every direction an that simply the money to cover the costs of leaving the EU. Even threesome (Fox, Davis, Boris) are starting to realise leaving the EU isn't as easy as their Master Farage told them it would be.

This is why I suspect either this budget or the next we are going see government raising substantial sums of money via tax rises, because they pretty much sold off all the family silver, what taxes will rise is the question.

BAE seemingly only interested in taking on MOD projects, which is tax funded anyway.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 11/22/2016 08:20 PM
Something I'd like people to keep in mind.  Let's just repeat that for people who think either of them looked at Skylon:

neither Musk or Beezos did much 'due-diligence' work on anything OTHER than the concepts they went forward with.

 ::)  Repeating such an assertion does not make it any more true.

Repeating the truth no matter how much some people may not like it does not make the statement false either :)

Both projects started with clear bias which were stated and quite visible up-front. No concepts beyond those already in mind were considered or 'traded' and this has been stated by both SX and BO. Neither considers Skylon as a viable concept, more to the point neither has any consideration that an air-breathing rocket engine capable of operation from zero-to-Mach 20 has any 'use' in their plans.

Both Musk and Beezos started with an idea of what they wanted in the end to have, it is no surprise that they ended up with pretty much what they wanted in the first place. There is no evidence that they seriously considered any concepts or ideas that did not fit their already pre-conceived ideas on what they would end up with, (which oddly enough is something REL is accused of doing as if it were a "bad" thing) and there IS evidence that the only 'trades' done were within the already defined parameters rather than anything more general and inclusive.

This isn't necessarily a "bad" thing as it allowed them to focus on what they felt was the 'optimum' solution to the situation and in the case of SX since they were "taking on" the already established industry in part to show that the process itself rather than any single design was faulty this makes sense.

It should also be very clear that while both companies have established that they can in fact 'beat' the bigger companies at their own game given the chance it should also be established they are doing so by playing the same game as those bigger companies rather than changing the rules as is often suggested. What SX and BO have done is nothing that anyone else with the same resources and drive could not accomplish in fact both LM and Boeing have proposed similar systems in the past and have been unable to 'sell' them at that time. Times have changed somewhat and both SX and BO have seized an opportunity to move their concepts forward but they remain very much wedded to the current operational space launch concept.

REL/Skylon/SABRE has also garnered increased interest and support if not at the same level and despite how much supporters of the straight SSTO concept feel 'let-down' by discussion of using SABRE in a TSTO concept the main point remains that its a complex and un-tried propulsion system that needs to be proven* in practice before it will be accepted so any forward progress IS progress :)

*=To put it mildly I am 'irked' significantly that in reality EVERYTHING about the SABRE concept has in fact been shown to be practical and hardware, (test if not flight weight) was tested to show this in the late 50s and early 60s but was dropped in the rush to accept that "Liquid Air Cycle," "Hypersonic Cruise" and "SCRamjets" were "required" for any air-breathing orbital concept. Coupled with the more recent, (and seemingly more pervasive) attitude that anything with 'wings' is the "Shuttle and therefor can never work as suggested" it makes it difficult to believe anyone can actually significantly lower the cost of space access when they refuse to actually examine all the possibilities rather than sticking to the 'usual' assumptions.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: CameronD on 11/22/2016 09:12 PM
*=To put it mildly I am 'irked' significantly that in reality EVERYTHING about the SABRE concept has in fact been shown to be practical and hardware, (test if not flight weight) was tested to show this in the late 50s and early 60s but was dropped in the rush to accept that "Liquid Air Cycle," "Hypersonic Cruise" and "SCRamjets" were "required" for any air-breathing orbital concept. Coupled with the more recent, (and seemingly more pervasive) attitude that anything with 'wings' is the "Shuttle and therefor can never work as suggested" it makes it difficult to believe anyone can actually significantly lower the cost of space access when they refuse to actually examine all the possibilities rather than sticking to the 'usual' assumptions.

Randy, it comes down to money (physics too.. but mostly money) in the end.  REL have been working on SABRE for how long now? Decades? ..and exactly what do they have to show their backers apart from a long list of receipts?  At the time the Wright Brothers made history, both gliders and petrol engines were tested technologies - but they had to do a lot more than stick the two together to get airborne.

Examining multiple possibilities (your 'due diligence') costs money also, rushing off down an endless list of rabbit-holes.  One reason NACA/NASA was founded in the first place was to allow this 'research' to be carried out without impacting private companies' (American companies in particular) wallets.. and the aerospace world in general is a better place for that.  ..But REL are not NASA and neither is UKSpace.

IF REL can't make SABRE work, then who can?  What it tells me is that getting the SABRE concept to actually, practically, work is far, far, more difficult than REL are prepared to publically admit.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 11/22/2016 09:13 PM
No one can 'break' a circle that in fact does NOT exist. Note that there IS a "demand" and a "market" in existence, the fact that it is not as large or extensive as some would like and that it does not in fact 'service' a market that does not exist but which some want to exist is totally beside the point.

But it does exist, which Skylon can service.

"Can" of course and the fact that Skylon is 'designed' to actually service that existing market puts it way ahead of MOST SSTO concepts which assume that orbit is "half-way-to-anywhere" is a truism rather than an observation :)

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The fallacy here is "we" need to "make" destinations and markets for reusable SSTO, (and yes that's the main argument FOR SSTO by the way) by building an extensive LEO orbital infrastructure for them to service.

And it's one that REL is aware of and does not subscribe. Enable yes, require, no.

Again which is a plus for REL. But as I've noted before the same would apply to a SABRE powered TSTO design since actually "servicing" doesn't require an SSTO. SSTO is nice but it's not a 'make-or-break' proposition either. My point in this conversation is that NOT having SSTO isn't going to mean the market won't ever come but neither will having it ensure they come about either. It's much more about the 'economics' of space rather than getting there as a prime driver. At this point in time we could have free access every day and not be able to economically exploit having that capability. (VERY crude analogy so please treat it as such :) )

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Not so obviously does this apply to SSTO vehicles mostly for the fact that MOST SSTO concepts have never managed to reach a comparable operational payload to an ELV or multistage reusable vehicle. Note I wrote "operational payload" rather than just 'payload' because in fact while Skylon is an SSTO it does in fact require a second stage to allow getting the 'payload' to the most in-demand destinations despite that fact. But at least REL was realistic about that and therefore designed the Skylon with more capacity than the average SSTO concept.

But note Skylon can support an "all electric" design by starting outside the Van Allan belts.

So can F9 and probably New Armstrong so that's not as much of a 'plus' as you might think. What sets Skylon apart from the other SSTO designs is REL at least admitted that "just" getting to orbit wasn't enough and started from the point of getting the payload AND a means to get it into the right 'place' from the start.

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And lastly on which is the better 'strategy' of builder/operator or builder to owner/operator for the most part the differing sides seem bound and determined to ignore history and reality to make their point :)
The latter ALWAYS takes over from the former once a certain level of traffic is reached as the builders can no longer afford to do both they inevitably form partnerships/consortiums to "buy" the vehicles and then own and operate them while they then concentrate on design and manufacture of new and improved vehicles. REL is simply assuming that the traffic levels will hit the levels that both SpaceX and BO are PLANNING on reaching and planning accordingly while SpaceX and BO are currently not looking to that point. Yet.

Careful about "historical inevitability"   :)

No one has managed to find a historical example where it didn't happen eventually so I'm probably safe :)

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While the market should transition to separate mfg and operators note that US market, where Boeing/TWA was probably broken up before this stage. IOW government intervention accelerated the split.

Actually the failure of Boeing to be able to provide the needed airframes for BOTH TWA and other airlines who demanded the 272 (IIRC) led to Douglas getting away from having to start its own airline to sell DC2's and the government only came along in pushing the process. It's not much different that Boeing and LM putting together ULA which initially was tasked with 'servicing' the Shuttle AND Boeing/LM commercial launch services. The "services" side gets to the point where it no longer makes economic or managerial sense to NOT have a more dedicated service organization. 

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But any kind of VTO rocket is a potential ICBM so the odds on bet is govt intervention will be negative. I don't see ULA, SX or Blue setting up a Guianna branch any time soon, do you?

That has almost nothing to do with "ICBM" since (technically anyway) the Soyuz "R7" booster is STILL listed as an "ICBM" and there wasn't much issue when the French decided they wanted to allow them to launch from Guianna :) Point of fact you won't see ULA/SX/BO launching from there simply because the owners don't WANT to allow competition to use their facilities. Similarly even if the US/UK actually cooperate to build a Skylon based launcher it probably wont' launch from there unless they are specifically ESA 'owned' and operated.

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Skylon does not look like an ICBM. It does not fly like an ICBM. It's very difficult to modify into an ICBM or an ICBM delivery vehicle and if you have the skills to do so you can probably make an ICBM yourself, so why bother?

Again "ICBM" has nothing to do with it as while it wouldn't make a very good weapons platform that in no way precludes it's USE as one. Commercial airliners* are not very "good' cruise missiles but that doesn't mean they can't be effective is used in that manner. And I'll point out that part of the whole IDEA of "selling" Skylons rather than operating them is to allow someone who does NOT have the ability to build an ICBM/LV to operate one.

*Point of fact we KNOW that they can make pretty good cruise missile busses and that's why sales are monitored

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Only the REL business model (and something like it's architecture) have a chance of getting away, of unifying the market by giving the economies of scale of a large market IE every payload on the planet but giving individual countries (or even corporations) the security of delivery of their payload.

That would be a good thing but it's not very realistic. See most nations/corporations do not NEED better 'security' for payloads as they know that launch providers can already meet most of their needs if they can't already launch themselves. The nations that do not have launch capability for the most part can rely on those that do to orbit any assets they might need 'more' security on as it is unlikely those assets will be used against those that provide the launch services. Further most nations that are not currently capable of launch do not NEED much in the way of space assets as they can easily access security. surveillance, survey, and monitoring satellite services from a number of commercial operators. This does not change significantly with increased space access. Lastly if someone DOES purchase a "private" Skylon they then find themselves significantly 'under-the-microscope' of other nations BECAUSE they feel a need for un-monitored and more 'private' space launch capacity which begs the question of WHY they would think they need that?

This bears repeating; Anything that can place a payload into orbit can also be used to drop something nasty on a neighbor up to half the world away and space launch is never going to be as 'routine' as air travel because of that simple fact. It doesn't matter that someone from South American with a private Skylon didn't MEAN to drop a failed launch onto Moscow at the moment of very high tension between the US and Russia but the result effects everyone on Earth if it's not handled just right. And that doesn't even touch someone WANTING to do some damage if they can.

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Telecos talk about the "last mile" of cable being the most expensive because there's so much of it to maintain and the individual payoff is so small but in space launch it's the first 100-200Km that's the major PITA. Skylon take that away in a way that no nation based rocket programme (and that includes Blue or SX) can ever do.

Now who needs to watch that 'historically inevitable' cliché? :)

Seriously, nothing shows that Skylon is going to be enough of a game changer to erase every other operational system when it's introduced. Honestly it's as complex as any other LV and while we can assume some operational simplicity by the time it flies systems by SX and BO could very well be much less operationally complex as well. And that assumes it doesn't fly as a TSTO itself which is probably more likely. Availability and flexibility are two of the more solid examples of what something like Skylon as a system could offer but as I pointed out above those are going to be tempered by outside factors and despite what Musk/Beezos want it's very much a question if they will get what they want. What REL wants is even more dependent on outside factors given the huge up-front requirements it needs to see operational use, and a bit LESS likely given their preferred operational mode.

Compromise very often doesn't let anyone get all of what they want but it's most often anyone gets any of what they want.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: oddbodd on 11/22/2016 09:22 PM
Just to nit-pick one thing. I did specify that the exploding thing was a hindrance to human presence, not cargo. Annual rocket failures seem to be bumping around in the 5% area, so 1 in 20 flights frequently has a fiery, premature end. Go to Heathrow and tell all those business and tourist travelers that every flight has a 1 in 20 chance of catastrophic failure, killing everyone aboard. Excluding the mentally ill, suicidal and people under extreme duress, I'll take a wild stab in the dark that zero people would choose to fly. Even if they were, there'd be no pilots or cabin staff willing to roll that D20-of-death every time they did their job. Hopefully the abort system in the SpaceX Dragon module will at least mean that it's just very expensive, instead of tragic.

Closer to 4% really (86 launches/5 failures in 2015, 72/1 this year) but the whole point was that humans ARE treated differently than cargo as in most transportation systems. Transport systems make a specific point to assure travelers that they have little chance of dying even in the worst case and given a "better than even" chance to survive an accident most people will willingly keep travelling. You would also be lying, (and liable :) ) if you told anyone that was their 'chances' in a launch accident since it's quite obvious that there are systems in place to keep the PEOPLE alive in the case of a failure. (None of the travelers at Heathrow have that option though and it does not seem to effect travel statistics)

OK, so 4%. I wasn't that far out, and you are using a very small sample size to argue the figure. I think the "1 in 20" is pretty widely accepted as a rule-of-thumb.

The reason Heathrow travel statistics aren't affected is because when people (often subconsciously) assess the risk of stepping onto a plane they conclude the risk is negligible. The US NTSB's preliminary stats for 2015 show no fatalities in all of their flights, and from the report http://www.usatoday.com/story/news/2016/02/15/2015-another-safe-year-airliners/80398194/ (http://www.usatoday.com/story/news/2016/02/15/2015-another-safe-year-airliners/80398194/) the worldwide equivalent is 1 in 3.1 million flights are lost.

According to many on this site if given the opportunity they would volunteer to ride a Dragon-1 WITHOUT an abort system come what may so I'd watch out throwing around the accusations of only the "mentally ill, suicidal and people under extreme duress" being willing to take their chances. If you've been over to the SpaceX ITS threads you'll note one discussing the lack of an abort system on the ITS which does in fact 'bother' some people but as noted it is in fact similar to current aircraft in that regard. If you are on an airplane that crashes you have no way of escaping and have to ride the plane to whatever the end point is, similarly if you were a passenger on Skylon you and the airframe are 'wedded' in fates. SSTO tends to assume a higher margin for 'safety' than a multistage design but in fact there is no basis for that assumption other than the "fact" that over their evolution most OTHER transport systems are 'technically' "single-stage" vehicles that have become much safer over time. Note that is OVER TIME during which they continually got safer and more efficient as they evolved.

You are comparing two very different groups of people there at different stages in the industries evolution. The group at Heathrow are not at the vanguard of the industry, pushing the boundaries. These people are just getting from A to B to do a job, or get some sun, or visit family. The journey is expected to be routine and boring, at least in the sense of surviving it. The people in the forums are space fans (nuts?), who you could liken more to the Emilia Earhart's of the early aviation industry, and willing to take that extra risk to be the first, push further, helping make the remarkable routine. I'd also point out that people sitting behind a keyboard safe at home will say a lot of things they won't back up in real life. Stick them in a flight suit in the elevator up to the crew capsule with that 1 in 20 hanging over them, and I wonder how many would still actually go through with it.

My point is and was that the "chances" of dying being launched in a current rocket are no worse than most other transportation accidents SPECIFICALLY because passenger transport is currently considered and addressed as a safety issue.

Huh? I really cannot understand you here. Unless you're referring to a current transport system that has already gotten in an accident, and you're only talking about the survivability of the accident. But when we decide whether to get on board a rocket or plane (or train, or boat, or car, or motorbike) we have to account for the risk that that act bording will result in being in a catastrophic accident.
1 in 20
vs.
1 in 3,100,000

Sure, if you're on the one that does have the accident, chances of surviving either type are low.

This is only "different" in designs that assume, with no data to back that up, that the vehicle is much 'safer' because it emulates a CURRENTLY "more safe" evolved design of another form of transportation. AKA it's "safer" because it resembles and airplane which is rather silly because what it looks like has almost nothing to do with what it actually DOES over the majority of it's flight and over that flight conditions change radically from anything any "airplane" does except the very beginning and very end.

Skylon is still a LAUNCH VEHICLE with all that implies.
I don't think I said in this that Skylon specifically would be automatically safer. Simply that significant human presence would require better than what we have now. Current rockets don't have a lot of scope for craft survival of a big failure. They tend to explode, tumble and disintegrate, slam back down on the pad and explode, and so on. In the event of a problem, there is one option for the passengers to survive, which is to get the hell out of there with a Launch Escape System. One crew has been saved by these in the past.

Bringing the Skylon design into this, no, we can't say that it will be safer. We can only say that the design may allow more options. It's design allows for powered flight with the loss of half it's thrust (a complete single engine failure). It's design allows for gliding to an emergency abort site with no thrust (although it'd have to dump fuel and be close enough). I think it would probably still have to have an LES itself for anything that resembled the proposed SPLM carrying people.

The Space Shuttle is possibly a closer analogue to the Skylon design than a rocket. They did 25 to 39 missions each for those that weren't lost, with a total of 139. The two that were lost were:
1) Columbia, where foam insulation fell off the disposable tank and damaged the wing, causing disintegration during reentry. Skylon design is SSTO, so no external tanks to shed bits.
2) Challenger, where a known design flaw was not yet fixed, and the temperatures increased the risk from that flaw, resulting in an SRB failing. Again Skylon design is SSTO, so no SRB's.

Of course, the Skylon design will have it's own problems, but 400 unmanned test flights should find and fix many of these. I imagine that way in the future, if Skylon is ever realised, a unit would get built, have a number of non-passenger flights, then provide the option to carry people, up till some limit. Then it would go back to non-passenger till retirement or loss.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: RanulfC on 11/22/2016 10:08 PM
Randy, it comes down to money (physics too.. but mostly money) in the end.  REL have been working on SABRE for how long now? Decades? ..and exactly what do they have to show their backers apart from a long list of receipts?  At the time the Wright Brothers made history, both gliders and petrol engines were tested technologies - but they had to do a lot more than stick the two together to make history.

Actually the money has always been the problem and it wasn't until REL began getting more that they managed to do more than component testing. And lets be honest they have a LOT to show investors as they DID test and prove those components which was the whole point. Much in the same way that in order to succeed the Wright's had to build their on engine, which many experts said was not possible mind you, in order to get the needed thrust. REL has to build it's engine to 'prove' what many say can't be done. Note that there is no physical (or physics) reason it should not in fact work as REL says it should it is simply that people don't believe it should work.

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Examining multiple possibilities (your 'due diligence') costs money also, rushing off down an endless list of rabbit-holes.  One reason NACA/NASA was founded in the first place was to allow this 'research' to be carried out without impacting private companies' (Musk's and Bezo's in particular) wallets.. and the aerospace world is a better place for that.  ..But REL are not NASA and neither is UKSpace.

Ahm well that was a 'reason' NACA was founded but due to a lack of government support they had to depend on industry to allow for many of the programs they ran. This caused issues since as a government agency NACA could not guarantee that something one section of industry paid for wasn't available to all industry. It wasn't until just prior to WWII that NACA began to get any significant budget to run with. At which point industry as a whole gained significantly. NASA on the other hand was meant to 'fix' part of that problem by ensuring American aeronautical research was given more rounded and steady funding. Then JFK threw everything for a loop and if it wasn't directly related to getting men to the Moon and back it got dropped. Things still haven't significantly changed in that NASA is still only allowed to spend money on authorized research and projects of which most are directly related to a 'current' program or can be linked in some way. This means a lot of promising programs and research still lack funding or support simply because they don't 'relate' to what the current interest is.

(I should probably point out that one of the main reasons NACA was created was to prevent someone like the Wright's from locking up aeronautical research behind patent walls to the detriment of overall American aeronautical progress which was felt at the time to have been significantly held back due to such practices prior to WWI)

Musk and Bezos started with a certain premise and went forward in that direction. I'm not blaming them or saying that's wrong but it would be nice for people to understand they had no intention of every looking beyond what they had in mind which is very often the case. People think that IF they knew and considered SABRE and then went ahead with their designs anyway that MUST mean that SABRE doesn't work which is clearly false from the outset. As they never considered it or even knew of it assuming they somehow 'rejected' it due to technological or "physics" reasons is totally false, but that's an 'assumption' that's made because they 'obviously' considered every possible method for getting to orbit. They didn't, they didn't even try. I would very much like that to be clear which was my point.

What I find really funny is in fact both NACA and NASA were aware of the general concept behind the SABRE cycle and specifically noted that the ONLY issue at the time it was studied was the lack of a viable heat-exchanger system AND the fact that their work required using "Liquid Air" as it was not clear that a rocket engine could be run on 'deep-cooled' air even though a subcontractor had indicated that it WAS possible. So if you want to think of it this way NASA in fact DOES know that SABRE is not only NOT a "rabbit hole" but that their own public records show they are well aware that no matter what else REL has solved the ONE problem they did have with the technology in the first place!

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IF REL can't make SABRE work, then who can?  What it tells me is that getting the SABRE concept to actually, practically, work is far more difficult than REL are prepared to publically admit.

Expensive does not equal difficult though to be honest the fact that REL is in a corner due to the requirements of the design is annoying. But NASA had issues with working with and exploiting liquid hydrogen which took billions of dollars and years of effort to get operational so it would only make sense with REL having a fraction of the budget and manpower available to NASA, (let alone NACA before it) it may take them longer to achieve.

I very much suspect I understand why REL hasn't made the connection to NASA's earlier work more clear but the fact that I among others have pointed out that connection and the relevant background but been ignored because NASA clearly isn't 'interested now' in the technology is annoying to say the least.

Money and access to it is the ONLY real problem facing REL, much as it has been from the beginning. Given their bias and obvious intent, (with some obvious issues both political and practical granted for a non-US company) neither Musk or Bezos would have invested in REL but the fact that have not should in no way reflect on the viability of the SABRE engine since they did not WANT to even consider that type of propulsion.

Randy
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: lkm on 11/22/2016 11:00 PM
So I was having a crazy thought about whether you could retrofit one of these ground development engines into an English Electric Lightning and how fast it would get before it melted/fell apart and it occurred to me that the thing on top of the 'D-21' could be a second engine, a small turbojet to allow powered flight once the cryogenic tanks are empty.
If the thing has wet wings then the extra fuel wouldn't get in the way of the cryogenic tanks and it would provide a measure of security that they wouldn't loose an expensive drone if the test engine failed.
Alternatively there are plenty of lightnings around the south of England and Alan Bond's into Spitfire restoration so he probably knows a guy.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/23/2016 07:00 AM
Actually the money has always been the problem and it wasn't until REL began getting more that they managed to do more than component testing. And lets be honest they have a LOT to show investors as they DID test and prove those components which was the whole point. Much in the same way that in order to succeed the Wright's had to build their on engine, which many experts said was not possible mind you, in order to get the needed thrust. REL has to build it's engine to 'prove' what many say can't be done. Note that there is no physical (or physics) reason it should not in fact work as REL says it should it is simply that people don't believe it should work.
Funny how people won't believe the fairly pedestrian thermodynamics of SABRE but one investor (the USG) will pour Billions into SCramjets when the detailed flow around the engine is still active research problem.
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Musk and Bezos started with a certain premise and went forward in that direction. I'm not blaming them or saying that's wrong but it would be nice for people to understand they had no intention of every looking beyond what they had in mind which is very often the case. People think that IF they knew and considered SABRE and then went ahead with their designs anyway that MUST mean that SABRE doesn't work which is clearly false from the outset. As they never considered it or even knew of it assuming they somehow 'rejected' it due to technological or "physics" reasons is totally false, but that's an 'assumption' that's made because they 'obviously' considered every possible method for getting to orbit. They didn't, they didn't even try. I would very much like that to be clear which was my point.
A point worth repeating.
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What I find really funny is in fact both NACA and NASA were aware of the general concept behind the SABRE cycle and specifically noted that the ONLY issue at the time it was studied was the lack of a viable heat-exchanger system AND the fact that their work required using "Liquid Air" as it was not clear that a rocket engine could be run on 'deep-cooled' air even though a subcontractor had indicated that it WAS possible. So if you want to think of it this way NASA in fact DOES know that SABRE is not only NOT a "rabbit hole" but that their own public records show they are well aware that no matter what else REL has solved the ONE problem they did have with the technology in the first place!
Mind you that problem is very far from non trivial. You can call it an "implementation detail" but it's a biggie.  Something I hope REL guard very carefully.
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Expensive does not equal difficult though to be honest the fact that REL is in a corner due to the requirements of the design is annoying. But NASA had issues with working with and exploiting liquid hydrogen which took billions of dollars and years of effort to get operational so it would only make sense with REL having a fraction of the budget and manpower available to NASA, (let alone NACA before it) it may take them longer to achieve.

I very much suspect I understand why REL hasn't made the connection to NASA's earlier work more clear but the fact that I among others have pointed out that connection and the relevant background but been ignored because NASA clearly isn't 'interested now' in the technology is annoying to say the least.
Don't forget that in the late 60's Rolls Royce did a development LH2/LO2 engine called the RZ20. This was a GG cycle with a LH2 turbopump, so the UK was not without LH2 experience. Access to NTRS does certainly help.  Personally I've always been baffled by NASA's insistence on solid shafts between turbopump turbines and impellers, give the substantial thermal expansion and compression forces involved. There are any number of couplings that could transmit force and simply absorb the longitudinal forces.
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Money and access to it is the ONLY real problem facing REL, much as it has been from the beginning.
Indeed. Their business model has made seeing a direct path from investing in them to seeing a return from the final product, but as a small company with limited resources that was the only way real way to go.
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Given their bias and obvious intent, (with some obvious issues both political and practical granted for a non-US company) neither Musk or Bezos would have invested in REL but the fact that have not should in no way reflect on the viability of the SABRE engine since they did not WANT to even consider that type of propulsion.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/23/2016 07:29 AM
OK, so 4%. I wasn't that far out, and you are using a very small sample size to argue the figure. I think the "1 in 20" is pretty widely accepted as a rule-of-thumb.

The reason Heathrow travel statistics aren't affected is because when people (often subconsciously) assess the risk of stepping onto a plane they conclude the risk is negligible. The US NTSB's preliminary stats for 2015 show no fatalities in all of their flights, and from the report http://www.usatoday.com/story/news/2016/02/15/2015-another-safe-year-airliners/80398194/ (http://www.usatoday.com/story/news/2016/02/15/2015-another-safe-year-airliners/80398194/) the worldwide equivalent is 1 in 3.1 million flights are lost.
With numbers of flights as small as those in spaceflight that 1% is quite a difference. Note also Shuttle has loss statistics IRL not much better than an expendable. But also note it was semi-reusable at best.


SSTO tends to assume a higher margin for 'safety' than a multistage design but in fact there is no basis for that assumption other than the "fact" that over their evolution most OTHER transport systems are 'technically' "single-stage" vehicles that have become much safer over time. Note that is OVER TIME during which they continually got safer and more efficient as they evolved.
What makes them safer is the elimination of staging and engine ignition events, both of which are complex and have  to work. This is called "intact abort." AFAIK it may be possible to add that to a TSTO if both stages run the same propellants, which after the retirement of Titan had not been the case in Western practice (with the exception of some Ariane upper stages). Historical (Bono style VTOL) expected to do limited engine restart of a segmented engine.

But the wings let you glide in a way that does not exist for any VTOL concept moving below about M5. That gives you time and control. BTW REL's goal has always been to accumulate flight hours and once they are high enough (and it's high by ELV standards but not by aircraft) get it certified safe for passengers.
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You are comparing two very different groups of people there at different stages in the industries evolution. The group at Heathrow are not at the vanguard of the industry, pushing the boundaries. These people are just getting from A to B to do a job, or get some sun, or visit family. The journey is expected to be routine and boring, at least in the sense of surviving it. The people in the forums are space fans (nuts?), who you could liken more to the Emilia Earhart's of the early aviation industry, and willing to take that extra risk to be the first, push further, helping make the remarkable routine. I'd also point out that people sitting behind a keyboard safe at home will say a lot of things they won't back up in real life. Stick them in a flight suit in the elevator up to the crew capsule with that 1 in 20 hanging over them, and I wonder how many would still actually go through with it.
Very true. Although I think 2 LV explosions is likely to put a dampener on such thoughts till an LES  arrives.  :(
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Huh? I really cannot understand you here. Unless you're referring to a current transport system that has already gotten in an accident, and you're only talking about the survivability of the accident. But when we decide whether to get on board a rocket or plane (or train, or boat, or car, or motorbike) we have to account for the risk that that act bording will result in being in a catastrophic accident.
1 in 20
vs.
1 in 3,100,000

Sure, if you're on the one that does have the accident, chances of surviving either type are low.
I don't think I said in this that Skylon specifically would be automatically safer. Simply that significant human presence would require better than what we have now. Current rockets don't have a lot of scope for craft survival of a big failure. They tend to explode, tumble and disintegrate, slam back down on the pad and explode, and so on. In the event of a problem, there is one option for the passengers to survive, which is to get the hell out of there with a Launch Escape System. One crew has been saved by these in the past.
And that's the real issue for anyone looking to massively raise the number of people in space.  :(

While you're using an ICBM architecture you will always need an artillery range in case  of a launch mishap.  Musk plans to side step this by putting a lot of people up at a time and (AFAIK) making the whole 2nd stage an LES.
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I think it would probably still have to have an LES itself for anything that resembled the proposed SPLM carrying people.
Dumping fuel (well actually the LO2 and most of the LH2 depending on wheather the engines still needed) alone reduces the explosion risk radically. Note again REL don't expect to get human certified without a lot of safely completed missions first. The goal is to let any Skylon be a passenger carrier. That means a passenger module inside the standard payload bay doors.
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The Space Shuttle is possibly a closer analogue to the Skylon design than a rocket. They did 25 to 39 missions each for those that weren't lost, with a total of 139. The two that were lost were:
1) Columbia, where foam insulation fell off the disposable tank and damaged the wing, causing disintegration during reentry. Skylon design is SSTO, so no external tanks to shed bits.
2) Challenger, where a known design flaw was not yet fixed, and the temperatures increased the risk from that flaw, resulting in an SRB failing. Again Skylon design is SSTO, so no SRB's.

Of course, the Skylon design will have it's own problems, but 400 unmanned test flights should find and fix many of these. I imagine that way in the future, if Skylon is ever realised, a unit would get built, have a number of non-passenger flights, then provide the option to carry people, up till some limit. Then it would go back to non-passenger till retirement or loss.
Actually the goal is once enough Skylons accumulate enough hours any of them can carry passengers.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Mutley on 11/23/2016 08:00 AM
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Don't forget that in the late 60's Rolls Royce did a development LH2/LO2 engine called the RZ20. This was a GG cycle with a LH2 turbopump, so the UK was not without LH2 experience.]Don't forget that in the late 60's Rolls Royce did a development LH2/LO2 engine called the RZ20. This was a GG cycle with a LH2 turbopump, so the UK was not without LH2 experience.



and erm.. one of the people involved in the design of the RZ20 engine was a Rolls Royce engineer by the name of Mr Alan Bond!
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: t43562 on 11/23/2016 09:05 AM

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I think you might be under the illusion that state support is bad...

No.  I just like to keep the lines clear on what is state aid and what is payment for services rendered.

I think you mean keeping the line unclear.  However you weasel around it, the state is helping an industrial sector to compete against foreigners - for whatever reasons and with whatever justification. Whether or not they have a right to is completely beside the point - I don't care about that and I can't see anyone else here who does.  It only matters in as much as it seems improbable at this time that one might survive without such arrangements.

No, Ron is right, there's a very clear line between payment for goods and services and payment that is not in exchange for goods and services, or above the price the government would have to pay for those goods and services from another source.  There's no weaselling involved.  It's the distinction that makes the most sense to make.

It's the difference between business and charity.

All you have to do is invent some reasons for the business and you're away, you can also choose a mechanism for doing it that spreads more money or less money around.  The whole set of reasons around it may be "nice-to-have" rather than critical to national survival which is true of some big infrastructure projects too.  Then you limit the competition to your own companies and hey presto - competitive advantage through state funding.   Without this kind of thing, SpaceX would be far behind at best or on powerpoint at worst and probably a lot of other industries in other countries too.

Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: ChrisWilson68 on 11/23/2016 10:21 AM

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I think you might be under the illusion that state support is bad...

No.  I just like to keep the lines clear on what is state aid and what is payment for services rendered.

I think you mean keeping the line unclear.  However you weasel around it, the state is helping an industrial sector to compete against foreigners - for whatever reasons and with whatever justification. Whether or not they have a right to is completely beside the point - I don't care about that and I can't see anyone else here who does.  It only matters in as much as it seems improbable at this time that one might survive without such arrangements.

No, Ron is right, there's a very clear line between payment for goods and services and payment that is not in exchange for goods and services, or above the price the government would have to pay for those goods and services from another source.  There's no weaselling involved.  It's the distinction that makes the most sense to make.

It's the difference between business and charity.

All you have to do is invent some reasons for the business and you're away, you can also choose a mechanism for doing it that spreads more money or less money around.  The whole set of reasons around it may be "nice-to-have" rather than critical to national survival which is true of some big infrastructure projects too.  Then you limit the competition to your own companies and hey presto - competitive advantage through state funding.   Without this kind of thing, SpaceX would be far behind at best or on powerpoint at worst and probably a lot of other industries in other countries too.

So you're claiming that somehow the ability to send cargo and crew to LEO is a "nice-to-have" but not necessary for NASA?  That they don't really need to resupply ISS, they're just doing it to keep SpaceX afloat?  I guess if there are people who believe the Apollo moon landings were a hoax, you'll find people who will believe anything.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: ChrisWilson68 on 11/23/2016 10:35 AM
Something I'd like people to keep in mind.  Let's just repeat that for people who think either of them looked at Skylon:

neither Musk or Beezos did much 'due-diligence' work on anything OTHER than the concepts they went forward with.

 ::)  Repeating such an assertion does not make it any more true.

Repeating the truth no matter how much some people may not like it does not make the statement false either :)

Both projects started with clear bias which were stated and quite visible up-front.

That's utter nonsense.  If you think that's true, cite a reference that shows that bias.

No concepts beyond those already in mind were considered or 'traded' and this has been stated by both SX and BO.

If you're going to claim SpaceX and Blue Origin said something, you'd better be prepared to cite a reference to prove it.

Neither considers Skylon as a viable concept,

Finally, you said something that is true.  But you've apparently misunderstood it.

To consider Skylon not to be a viable concept is to have a judgement about it.  To have a judgement about it means it was considered.

more to the point neither has any consideration that an air-breathing rocket engine capable of operation from zero-to-Mach 20 has any 'use' in their plans.

Of course they don't have it in their plans -- they considered it and rejected it early on.  That's not evidence of a bias.

Both Musk and Beezos started with an idea of what they wanted in the end to have, it is no surprise that they ended up with pretty much what they wanted in the first place.

Nonsense.  What they started with was a dissatisfaction with the current state of the launch industry and a desire to find some way to revolutionize it to lower costs and expand access.  They looked into how to revolutionize the launch industry and both independently came to the same conclusion: vertical launch and landing of chemical two-stage reusable rockets.

Neither one of them had any background in rockets.  The idea that they would start out with vertical take-off and landing reusable rockets as a preconceived idea makes no sense whatsoever.

There is no evidence that they seriously considered any concepts or ideas that did not fit their already pre-conceived ideas on what they would end up with, (which oddly enough is something REL is accused of doing as if it were a "bad" thing) and there IS evidence that the only 'trades' done were within the already defined parameters rather than anything more general and inclusive.

If you're going to claim there is evidence, present that evidence.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Coastal Ron on 11/23/2016 03:19 PM
I think you mean keeping the line unclear.

No, I meant what I said, and I like to use clearly defined and accepted definitions for words.

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However you weasel around it, the state is helping an industrial sector to compete against foreigners - for whatever reasons and with whatever justification.

Regarding the Falcon 9, if you look into the contracts that SpaceX has won from NASA, no money was designated for building the Falcon 9.  The only contracts SpaceX has won are related to ensuring that their Dragon spacecraft is able to carry and deliver cargo to the ISS (i.e. COTS & CRS), and that they can safely carry and deliver humans to the ISS (i.e. CCDev 1&2, CCiCap, & CCtCap), and for all the contracts SpaceX has had to deliver or accomplish specific goals in order to be compensated.

In contrast, a subsidy would be a payment to a company with no expectation of a product or service in return.  That is typically what "state aid" is, but as I've described, that is not the case with SpaceX and NASA.

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Whether or not they have a right to is completely beside the point - I don't care about that and I can't see anyone else here who does.  It only matters in as much as it seems improbable at this time that one might survive without such arrangements.

This regards U.S. companies having access to taxpayer funded NASA research.  I don't know, but I would imagine this happens in every democracy, and likely in the UK.  Have you researched it?

Because it makes no sense to the taxpayer to NOT make it available to domestic industry to increase the overall GDP.  Right?  So this is not just a NASA issue, but what many government do.  Otherwise you're just wasting taxpayer money, and that would not be in the best interests of anyone...
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: t43562 on 11/23/2016 03:59 PM
I think you mean keeping the line unclear.
...
Because it makes no sense to the taxpayer to NOT make it available to domestic industry to increase the overall GDP.  Right?  So this is not just a NASA issue, but what many government do.  Otherwise you're just wasting taxpayer money, and that would not be in the best interests of anyone...

I think you're arguing about something different - like you're making some defensive WTO presentation about protectionism. That is not relevant to Skylon or this thread.

I'm trying to point out something quite different which is that without a similar arrangement I think it is going to be difficult to see Skylon and SABRE take off.  I think some government needs to make up some random goal (e.g. "provide sovereign access to space" or some other nonsense) and put it out to contract in such a way that Reaction Engines and possibly several other smaller developers are highly likely to get a big chunk of money and can demonstrate whatever :-).  It could be the same as an air ministry specification for a new aircraft.

Essentially providing money for a goal that isn't commercial is what I mean.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/23/2016 04:09 PM
Coupled with the more recent, (and seemingly more pervasive) attitude that anything with 'wings' is the "Shuttle and therefor can never work as suggested" it makes it difficult to believe anyone can actually significantly lower the cost of space access when they refuse to actually examine all the possibilities rather than sticking to the 'usual' assumptions.
Not quite.

In the UK, anything winged, big and fast was viewed like Concorde, which British civil servants had a horror of repeating.  :(

It has literally taken the retirement or death of a generation of senior civil servants, to get the UKG to consider helping (slightly) a UK company do a winged vehicle and a launch vehicle.   :(

Something I'd like people to keep in mind.  Let's just repeat that for people who think either of them looked at Skylon:

neither Musk or Beezos did much 'due-diligence' work on anything OTHER than the concepts they went forward with.

 ::)  Repeating such an assertion does not make it any more true.
OK then where have they mentioned when either of them said they looked at HTOL and concluded it was unworkable?

Given Musk's goal has always been Mars I doubt he spent a second on the idea. As anyone with a cursory knowledge of spaceflight and general engineering would expect. REL don't want to build a Skylon that can land on Mars. They'd be happy to enable a greatly cheaper Mars mission based on Skylon flights to LEO however.

So where did Bezos mention this? Interview? Media event? Tweets?

You seem so very sure he's wrong. Do you have facts or just your simple faith to guide you?
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: lkm on 11/23/2016 04:27 PM
I think you mean keeping the line unclear.

No, I meant what I said, and I like to use clearly defined and accepted definitions for words.

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However you weasel around it, the state is helping an industrial sector to compete against foreigners - for whatever reasons and with whatever justification.

Regarding the Falcon 9, if you look into the contracts that SpaceX has won from NASA, no money was designated for building the Falcon 9.  The only contracts SpaceX has won are related to ensuring that their Dragon spacecraft is able to carry and deliver cargo to the ISS (i.e. COTS & CRS), and that they can safely carry and deliver humans to the ISS (i.e. CCDev 1&2, CCiCap, & CCtCap), and for all the contracts SpaceX has had to deliver or accomplish specific goals in order to be compensated.

In contrast, a subsidy would be a payment to a company with no expectation of a product or service in return.  That is typically what "state aid" is, but as I've described, that is not the case with SpaceX and NASA.

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Whether or not they have a right to is completely beside the point - I don't care about that and I can't see anyone else here who does.  It only matters in as much as it seems improbable at this time that one might survive without such arrangements.

This regards U.S. companies having access to taxpayer funded NASA research.  I don't know, but I would imagine this happens in every democracy, and likely in the UK.  Have you researched it?

Because it makes no sense to the taxpayer to NOT make it available to domestic industry to increase the overall GDP.  Right?  So this is not just a NASA issue, but what many government do.  Otherwise you're just wasting taxpayer money, and that would not be in the best interests of anyone...
Absolutely it's not state aid. It's state support of an industry. Which is what we're talking about.
A decade ago the U.K. Government paid BAE to build Taranis a UCAV  stealth x-plane because BAE didn't have anything for their designers to work on and wanted to develop some competency in stealth and UAV's. That wasn't state aid but was absolutely state support of the industry and there's no reason they couldn't  follow up Taranis with paying  BAE to build a hypersonic test vehicle.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/23/2016 04:34 PM
Finally, you said something that is true.  But you've apparently misunderstood it.
To consider Skylon not to be a viable concept is to have a judgement about it.  To have a judgement about it means it was considered.
Wow, what an amazingly twisted piece of logic.

Seriously you're going to claim Musk looked at Skylon and thought "How can I land this on Mars?"

When you a) know your end goal is another planet b)Have limited resources c)have no requirement to carry out any kind of "competition" for proposals.

Only governments have to put up with nonsense. It's the reason no Shuttle proposal could have a plug nozzle, because that would mean only Rocketdyne could supply the engine and that would not be "fair."  :(

And the rest is now history.
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Of course they don't have it in their plans -- they considered it and rejected it early on.  That's not evidence of a bias.
Ahhhh,I see. So if they spent 5 seconds or 5 months looking at an option it's still "considered." Is that about right?

Both Musk and Beezos started with an idea of what they wanted in the end to have, it is no surprise that they ended up with pretty much what they wanted in the first place.
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Nonsense.  What they started with was a dissatisfaction with the current state of the launch industry and a desire to find some way to revolutionize it to lower costs and expand access.  They looked into how to revolutionize the launch industry and both independently came to the same conclusion: vertical launch and landing of chemical two-stage reusable rockets.
I notice you miss out the time factor in this and the knowledgebase (IE risk)) element in this. Once you factor that in VTOL rockets always come to the top of the list because if you want to do what you've already done you use what's already been done.

And in fact Bezos and Musk did not  choose the identical path. Musk went the start fast/Get to the competition level/Hope something turns up Silcon Valley startup route and Bezos has been a bit more measured but not started generating revenue.
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Neither one of them had any background in rockets.  The idea that they would start out with vertical take-off and landing reusable rockets as a preconceived idea makes no sense whatsoever.
And the fact that 90%+ of the literature on RLV's would be for VTOL and that all of the practicing rocket engineers they spoke to were AFAIK VTO rocket engineers and the only US example of a HTO rocket was the Pegasus didn't bias their thinking?

Really?
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If you're going to claim there is evidence, present that evidence.
Here's the question I can't figure out the answer to. Why is it so important to you that you claim Bezos and Musk looked at SABRESkylon and rejected it?

It's not a good fit for Musk's end game and it's too big and risky for Bezos.

Which we already knew.

Neither is going to use it for their goals.

So  what's your point? Tell us what you think this "proves," because as you said, neither has a background in rockets and AFAIK Bezos has no involvement other than signing the checks (which is important and noble work and no doubt greatly under appreciated by the people who spend the money  :) )
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Lars-J on 11/23/2016 05:33 PM
Something I'd like people to keep in mind.  Let's just repeat that for people who think either of them looked at Skylon:

neither Musk or Beezos did much 'due-diligence' work on anything OTHER than the concepts they went forward with.

 ::)  Repeating such an assertion does not make it any more true.
OK then where have they mentioned when either of them said they looked at HTOL and concluded it was unworkable?

Given Musk's goal has always been Mars I doubt he spent a second on the idea. As anyone with a cursory knowledge of spaceflight and general engineering would expect. REL don't want to build a Skylon that can land on Mars. They'd be happy to enable a greatly cheaper Mars mission based on Skylon flights to LEO however.

So where did Bezos mention this? Interview? Media event? Tweets?

I don't think you understand how this works. YOU made the claim, with no evidence to back it up. I challenged it.

But since you asked, here is what Musk has said about air breathing launch vehicles: http://shitelonsays.com/transcript/elon-musk-lecture-at-the-royal-aeronautical-society-2012-11-16   (search in page for 'reaction engines')

You seem so very sure he's wrong. Do you have facts or just your simple faith to guide you?

Pot, kettle, black? You are so convinced that Skylon is the way forward, that anyone who did 'due diligence' on it must have selected it, and the only way one could explain them not selecting that path is by not doing 'due diligence'.  ::)

I know we are in a post-facts society, but at least TRY to step out of your bubble.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Khadgars on 11/23/2016 05:58 PM
Something I'd like people to keep in mind.  Let's just repeat that for people who think either of them looked at Skylon:

neither Musk or Beezos did much 'due-diligence' work on anything OTHER than the concepts they went forward with.

 ::)  Repeating such an assertion does not make it any more true.
OK then where have they mentioned when either of them said they looked at HTOL and concluded it was unworkable?

Given Musk's goal has always been Mars I doubt he spent a second on the idea. As anyone with a cursory knowledge of spaceflight and general engineering would expect. REL don't want to build a Skylon that can land on Mars. They'd be happy to enable a greatly cheaper Mars mission based on Skylon flights to LEO however.

So where did Bezos mention this? Interview? Media event? Tweets?

I don't think you understand how this works. YOU made the claim, with no evidence to back it up. I challenged it.

But since you asked, here is what Musk has said about air breathing launch vehicles: http://shitelonsays.com/transcript/elon-musk-lecture-at-the-royal-aeronautical-society-2012-11-16   (search in page for 'reaction engines')

You seem so very sure he's wrong. Do you have facts or just your simple faith to guide you?

Pot, kettle, black? You are so convinced that Skylon is the way forward, that anyone who did 'due diligence' on it must have selected it, and the only way one could explain them not selecting that path is by not doing 'due diligence'.  ::)

I know we are in a post-facts society, but at least TRY to step out of your bubble.

To make it easier, I've listed Elon's response to Reaction Engines from your link.

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[Question about Reaction Engines.] This is using an air breathing engine? When I looked at the numbers it didn't seem too compelling compared to having a slight increase in the size of the first stage. So if you're going to add a whole bunch of complexity, it needs to really pay off and, at least using the numbers I've seen, I have a hard time seeing how it does pay off - but I could be wrong about that. If there is really a big advantage then it would be worth investigating, but it would have to be a big advantage. I would be reluctant to add essentially some sort of jet engine on top of the rocket engine problem.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Alpha_Centauri on 11/23/2016 06:05 PM
So in other words he hasn't seriously investigated it.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: Khadgars on 11/23/2016 06:12 PM
So in other words he hasn't seriously investigated it.

He's looked at the numbers and it didn't make sense to him.  The payoff had to be too large to make it worth while, though he leaves the door open to being wrong.
Title: Re: The Reaction Engines Skylon Master Thread (6)
Post by: john smith 19 on 11/23/2016 10:36 PM
In truth given Musk's end game is Mars it would be very surprising if he'd taken any kind of serious look at SABRESkylon since SABRE shines in a HTOL vehicle.

No one who's followed Musk would be surprised at this. Musk and SX are focused on Mars and this has allowed them to filter everything through 1 simple question. "Does this get Elon to Mars faster, cheaper, safer or not."  That's lead them to turning down at least one concept already and of course the F3 and F5 never left the CAD screen. Not needed, not saleable and not going get Elon to Mars faster.

He thinks he can get the improvement in launch costs with an architecture that works on Earth and Mars. Time will tell if he's right.

Can we leave the "celebrity endorsements" AKA "The Halo Eff