Author Topic: The Reaction Engines Skylon Master Thread (5)  (Read 420230 times)

Offline Star One

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1440 on: 03/30/2016 09:28 PM »
It was my understanding that none of this promised 60 million had been so far received?
From the report, it would appear your understanding is correct:

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Mark Wood:
"Let me give you a local example. Reaction Engines received a tremendous boost when it
was announced that we had achieved 60 million of Government investment back in 2013,
but it took two and a half years to get the grant agreement signed, and three years later we
still have not seen any of those funds flowing into the company. Potentially, it is a missed
opportunity in that it has given our competitors an extra three years to try to find ways to
beat our engine."

I wonder why the government have suddenly got cold feet on this, Treasury meddling?

Offline t43562

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1441 on: 03/30/2016 09:47 PM »
I wonder why the government have suddenly got cold feet on this, Treasury meddling?

The impression given in the recent parliamentary hearing by Mark Thomas was just that the wheels grind slowly. I am not sure on the EU rules about state aid but you can imagine that some issue like that has probably gummed up the works. e.g. could it be that matching funds are required from industry? He didn't really explain and probably doesn't want to cause any upsets.

Offline lkm

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1442 on: 03/30/2016 10:00 PM »
I believe it's been mentioned in lectures that they had a major funder drop out so the government money which was unlocked by a certain level of private finance couldn't be. At least that's my understanding.

Offline A_M_Swallow

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1443 on: 03/30/2016 10:34 PM »

It was my understanding that none of this promised 60 million had been so far received?

I guess we would all agree the UK government should honour  their 60 million promise to RE.

How about  this forum creating a petition we could present to HM government.

I fully understand if the management of this forum do not wish to dip their toes into politics, but do we just say nothing and allow government to play politics with the aero space industry.

Britain's new financial year starts on 5 April. That is less than a week away. With civil service reaction times do not do anything until May, unless you know the money has been denied. The new money could just be stuck in committee, (there are lots of committees).

Offline knowles2

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1444 on: 03/30/2016 10:50 PM »
way to many committees in this country.

Offline topsphere

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1445 on: 03/31/2016 12:39 AM »
As I understand it (from what I have been told), the 60m pledge will be honoured, just taking a lot longer to sort through bureaucratic details with HMG and UKSA than REL would like.
« Last Edit: 03/31/2016 12:44 AM by topsphere »

Offline lk555

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1446 on: 03/31/2016 03:45 AM »
Has anyone looked at the possibility of applying tri-propellant technology to the SABRE? So the hydrogen is the main propellant taking up most of the volume of the airframe, and its still a big airframe even with reduced sizing of the oxygen tanks. So what about using a tri-propellent, use kerosene with the air breathing initial stage, then switch over to LH2 for the rocket portion where it would have a bigger advantage? Means you minimise storage size and therefore airframe mass? Plus that tank would need less insulation on ascent as its not cryogenic?

Sabre looks to be using a fuel rich staged combustion set up, has there been a kerosene staged combustion cycle? I suppose its just adding complexity to the entire thing, but am I completely out there?

Offline hkultala

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1447 on: 03/31/2016 03:49 AM »
Has anyone looked at the possibility of applying tri-propellant technology to the SABRE? So the hydrogen is the main propellant taking up most of the volume of the airframe, and its still a big airframe even with reduced sizing of the oxygen tanks. So what about using a tri-propellent, use kerosene with the air breathing initial stage, then switch over to LH2 for the rocket portion where it would have a bigger advantage? Means you minimise storage size and therefore airframe mass? Plus that tank would need less insulation on ascent as its not cryogenic?

Would not work. The cold hydrogen is needed to cool the air entering the engine during the airbreathing mode.
« Last Edit: 03/31/2016 03:50 AM by hkultala »

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1448 on: 03/31/2016 09:41 AM »
What this article neglect to say is that the whole engine can be tested and develop on the ground until all of the main problems, such as wear and tear of the combustion chambers are solved.
True. It is a fact the SSME combustion chambers tubes started failing at 1/3 their predicted lifespan. The extreme thermal shock during startup caused "dog kenneling" A fair chunk of the modern theory around thermal stress (IIRC it's called the "visco-elasto-plastic" stress model) was developed specifically to explain this massive discrepancy between theory and practice.

What people forget about SABRE is that LH2 is not used to cool the chambers tubes. That's done by deeply precooled air from the inlet and later LO2 from the tanks.

Both have been tested at DLR in Germany and worked fine.
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An well it not surprising the main criticism of Skylon come from people who are pursuing Scramjets, surely most funding for that dream would cease.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline RanulfC

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1449 on: 03/31/2016 03:08 PM »

A scramjet can go up to Mach 10.

Just so we're all on the same page here, a "Supersonic Combustion Ramjet" (SCramjet) can (in theory :) ) accelerate indefinitely though material and aerodynamic issues would probably limit any "actual" SCramjet vehicle to somewhere below Mach-30. That's the "draw" of the concept and always has been.

Reality? Not so much. The X-43 managed somewhat below Mach-9.8 and that was with the rocket booster pushing it nearly to that speed BEFORE the SCramjet took over. As noted everything we've seen (both on the bench and now with flight testing) shows the SCramjet isn't an efficient or effective accelerator.

Then again, that's not what the military is looking at them for :)

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Mach 5 you can do with a turboramjet, to my knowledge.

Turboramjets have been operated up to around Mach-4, with modifications and various techniques they can probably be pushed to Mach-5 or a bit over but it's not worth the cost of doing so. (Mostly because doing so requires removing the turbofan/jet from the ramjet duct to allow the ramjet to reach peak efficiency in operation which would then allow speeds up to Mach-10 according to people who actually designed and built ramjets for a living. The same folks were telling anyone who would listen since the 1960s that a SUB-sonic combustion ramjet could do Mach-10 if anyone was willing or needed to build one. The got drowned out by the SCramjet crowd)

Just an FYI, but a standard low-to-medium bypass turbofan can be used to get to Mach-4 and some change with a few bolt-on systems but there's been no 'need' for doing so.

Randy

From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1450 on: 03/31/2016 03:09 PM »
I'll note that people who love the SCRamjet concept never talk about it's T/W or the very large system needed to get it up to operating speed.

Well in honesty you need some added systems to go from "zero-to-start" for any combined cycle system. That includes SABRE :)

But I agree that the SCramjet-uber-alles crowd tends to downplay FAR to much of the required effort. Sure you can accelerate to Mach-30+ but if it takes a week-and-a-half to do so what's your operational incentive?

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It took me years to discover the current expected T/W for a SCRamjet is about 2:1. That's less than the combined J58/nacelle combination (and the combination was key to making the system work) for the SR71 in the mid 1950's.

Actually BENCH SCramjets have had much higher T/W ratios but working with a "real" atmosphere (and a real intake and exhaust rather than a lab set up) hasn't been anywhere near where it was predicted from the bench tests.

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6 decades of effort (starting roughly in 1960 at Johns Hopkins APL) has produced this.

And if past experience has taught us anything it will take a few more decades of SERIOUS work (and money) to get to an effective operational system. The main problem is, while SCramjet LOOKS good in theory it has very few 'real-world' operational uses. Unfortunately SABRE, ATR, SERJ and most other proposed "space" vehicle air-breathing systems have the same problem.

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Historically fixed geometry ramjets have been good for a an operating Mach range of about 3 IE M1-M4 M2-M5 at most disregarding the weight of the rocket (including propellant) or air breathing engines to get it there.

"Fixed" inlets yes, but like SABRE almost no one suggests using a fixed inlet/exhaust for a space launch accelerator system. (And interestingly, fixed inlet systems have turned out to be more flexible than assumed with higher speed 'sweet-spots' above their design points. Combined with some additive (injection) systems it's been shown that you can achieve similar results to having a fully adjustable mechanically variable inlet system with far less mass and cost. However this method isn't as operationally flexible as actual adjustable inlets which is why it was not pursued beyond testing)

And I have to disagree that unlike the SCramjet crowd those who suggest various combined cycle space launch concepts DO include and are very obvious at pointing out the combined systems mass. That's actually a major point in that combined systems mass significantly less than separate systems employed in the same vehicle.

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SABRE design (as it was planned to from day one) covers the whole range from 0 to M23. The downside is it's poor (but only  by rocket standards) T/W ratio (which is 50% better than state of the art turbofans).

No different than several other proposed and tested combined cycle system really. SABRE buys a few advantages with the extensive pre-cooling rather than going down the dead-end "Liquid Air Cycle" route that most prior work in the 50s and 60s went but most more modern concepts (since the 1970s) have avoided that pitfall. Strangely enough, simply injecting water into the intake of a semi-modern low-bypass turbofan like the F100 will double the T/W and it would still have a higher ISP than the SABRE. Toss in significant pre-cooling of the air such as the SABRE pre-cooler system and it increases yet again with no ISP loss.

However, (as noted) this won't get you much past Mach-5 and is only an air-breathing mode concept.

SABRE isn't alone in being designed for SSTO operations from the start is my main and significant point.

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SABRE buys a huge propellant tank (provided by the airflow through it) and that makes it's relatively poor IE T/W ratio 7x better than SCRamjet, performance, coupled with it's excellent air breathing Isp good enough to get the job done.

True, for a "versus-SCramjet" comparison, but it compares more evenly with just about any combined cycle engine system that doesn't (which is difficult these days I will admit) include a SCramjet.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1451 on: 03/31/2016 03:54 PM »
This was the original REL concept for a Nacelle Test Vehicle:

Would seem to be about the right size but mass looks really, really low. The GTX test vehicle (RBCC engine test bed) for a similar flight test pattern was about the same size, (37.3ft=11.3m long by 14.5ft=4.4m wingspan compared to 29.5ft=9m long and 11.5ft=3.5m wingspan) but mass was much higher than 1000kg. (Propellant mass for the LH2 was listed as 589lbs/267kg) Even without the SRBs the flight test vehicle was around 7,937lbs/3600kg fully fueled and it was using some pretty light-weight structural materials.
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20030055618.pdf

Wingspan alone is going to have to go up to support an HTOL take off and glide back whereas the GTX was VTO and only used stub wings and body lift because it 'started' at over Mach-2.

The D-21 (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000004765.pdf) was 42.9ft/13.07m long, 7.1ft/2.1m high with a 19.1ft/5.8m wingspan using JP-7/8 fuel though as noted it was in a very compact tank compared to LH2. Interestingly, modifications for the DRACO RBCC concept test bed, changed the overall dimensions very little, (44"+"ft long, wingspan to 19.5ft, etc http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000012490.pdf) though the mass went up, it was not as much as one might expect. Given the configuration of the SABRE compared to the more integrated DRACO RBCC I suspect it would probably be EASIER to modify the D-21 to house a small scale SABRE prototype. If of course the SABRE can be scaled down sufficiently.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1452 on: 03/31/2016 07:44 PM »

The D-21 (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000004765.pdf) was 42.9ft/13.07m long, 7.1ft/2.1m high with a 19.1ft/5.8m wingspan using JP-7/8 fuel though as noted it was in a very compact tank compared to LH2. Interestingly, modifications for the DRACO RBCC concept test bed, changed the overall dimensions very little, (44"+"ft long, wingspan to 19.5ft, etc http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000012490.pdf) though the mass went up, it was not as much as one might expect. Given the configuration of the SABRE compared to the more integrated DRACO RBCC I suspect it would probably be EASIER to modify the D-21 to house a small scale SABRE prototype. If of course the SABRE can be scaled down sufficiently.
Interesting idea about using the D11 as the DRACO test bed. It seemed quite reasonable. Very pragmatic, and relatively cheap. I guess it got lost in the budget. Too bad.  :(

AFAIK the joker in scaling down SABRE (and why REL are reluctant to do one) was to be a real test of the engine it's got to be at full chamber pressure.  That combo of full pressure but low flow rates gives a very high speed turbo pump design.

Now if SABRE 4 allows a lower chamber pressure for the air breathing part that may make the pump design more reasonable. Obviously the RL10 demonstrates expansion drive in fairly small sizes is possible. I think the chamber pressure was the issue.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline RanulfC

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1453 on: 03/31/2016 09:19 PM »

The D-21 (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000004765.pdf) was 42.9ft/13.07m long, 7.1ft/2.1m high with a 19.1ft/5.8m wingspan using JP-7/8 fuel though as noted it was in a very compact tank compared to LH2. Interestingly, modifications for the DRACO RBCC concept test bed, changed the overall dimensions very little, (44"+"ft long, wingspan to 19.5ft, etc http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000012490.pdf) though the mass went up, it was not as much as one might expect. Given the configuration of the SABRE compared to the more integrated DRACO RBCC I suspect it would probably be EASIER to modify the D-21 to house a small scale SABRE prototype. If of course the SABRE can be scaled down sufficiently.
Interesting idea about using the D11 as the DRACO test bed. It seemed quite reasonable. Very pragmatic, and relatively cheap. I guess it got lost in the budget. Too bad.  :(

Actually it was a good idea but getting the D21 to the point where it was going to be able to work at speeds over the 'nominal' 3.5 was going to cost to much. Up to that point the D21 was great, beyond it? Not so much. And in the end simply "flying" the DRACO wasn't worth it. Pretty much the same story for any combined cycle power plant really.

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AFAIK the joker in scaling down SABRE (and why REL are reluctant to do one) was to be a real test of the engine it's got to be at full chamber pressure.  That combo of full pressure but low flow rates gives a very high speed turbo pump design.

Now if SABRE 4 allows a lower chamber pressure for the air breathing part that may make the pump design more reasonable. Obviously the RL10 demonstrates expansion drive in fairly small sizes is possible. I think the chamber pressure was the issue.

Which is what I gathered from what REL was saying which means at 'best' we're talking about a single, full-size, Skylon/SABRE nacelle as a test vehicle which is NOT going to be cheap in any sense of the word. And there's the sticking point :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline SICA Design

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1454 on: 04/01/2016 07:56 AM »
This was the original REL concept for a Nacelle Test Vehicle:

Would seem to be about the right size but mass looks really, really low... 

...Given the configuration of the SABRE compared to the more integrated DRACO RBCC I suspect it would probably be EASIER to modify the D-21 to house a small scale SABRE prototype. If of course the SABRE can be scaled down sufficiently.

Randy

I agree; what I remembered shortly after digging out this concept was REL's thinking at the time:

Almost every aspect of SABRE can be tested on the ground - except the aerodynamics (e.g. maintaining shock on lip) of the nacelle under real flight conditions. Hence this is a NACELLE Test Vehicle, probably boosted by non air-breathing conventional rockets mounted within.

Explains the low mass and the lack of significant LH2 storage volume (and the loss of the endearing banana shape!).

Not sure whether this half-way approach would ever come back into favour...
« Last Edit: 04/01/2016 08:07 AM by SICA Design »

Offline ChrisWilson68

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1455 on: 04/02/2016 03:41 AM »
The scramjet research and the people involved have no sensible bearing on space launch, so why the hell ask them to comment on SABRE?

Scramjet researchers may be biased.  But so might the people at REL.  Scramjet researchers are experts on propulsion at these speeds.  There's basically just them and REL.  Both could potentially have some bias, but if you want a perspective from outside REL, there's nobody better to give it than scramjet researchers.

Whether the goal is space launch or missiles, it's still propulsion at hypersonic speeds.

So, it makes sense to be wary of what scramjet researchers say about Skylon, and keep a critical frame of mind, but not to dismiss it out of hand.

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1456 on: 04/02/2016 08:13 PM »
The scramjet research and the people involved have no sensible bearing on space launch, so why the hell ask them to comment on SABRE?

Scramjet researchers may be biased.  But so might the people at REL.  Scramjet researchers are experts on propulsion at these speeds.  There's basically just them and REL.  Both could potentially have some bias, but if you want a perspective from outside REL, there's nobody better to give it than scramjet researchers.

Whether the goal is space launch or missiles, it's still propulsion at hypersonic speeds.

So, it makes sense to be wary of what scramjet researchers say about Skylon, and keep a critical frame of mind, but not to dismiss it out of hand.
Actually there are also the groups who build ramjets for missiles.

But that's not really considered "research" as they can deliver systems that work already.  M3.5-4 has certainly been proven since the late 70's.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Online Radical_Ignorant

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1457 on: 04/04/2016 02:17 PM »
The technology is scalable.  Last time I asked, REL had not run into any upper limit, and there's no real reason you couldn't make it a bit smaller if that would fit the market better.

But if you try to make it a lot smaller, you run into problems.  Alan Bond has noted that a subscale development engine like the one they were planning originally would have issues with the extreme speed of the hydrogen turbopump (~300krpm or something), which would cost quite a bit to develop.  Hence their eagerness to go to full scale on the engine prototype when it looked like they'd have a chance to do so.

Upper scale is existing infrastructure. Even A380 was scaled up to where infrastructure allowed and no more. And there are more money as for now in civilian jets than in space transports.

But making it smaller. I heard that it's rather impossible or would not reduce costs at all. However I won't provide link. I think it was one of their speeches, but there is only my far from perfect memory for that. If you can prove me wrong by some link, I'd be grateful. That would be really nice if they could scale it down and make cheaper version. I thought that was the reason they go for full scale.

Offline Ravenger

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1458 on: 04/04/2016 03:28 PM »
According to REL the main issue with scaling down the SABRE engine is the LH2 turbopump. A smaller turbopump requires much higher RPM, which makes it much more technically difficult to produce. I think the figure quoted was 100m just to develop the turbopump alone.

This is why REL previously ruled out a sub-scale SABRE demonstrator.

Online adrianwyard

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1459 on: 04/04/2016 03:48 PM »
Right, that is one component that we believe is hard to scale down. But the rest of the Skylon system is sized to launch comsats - one of the easiest business cases to make for a launcher.

However IIUC, if REL find a customer with a fat wallet that needs a smaller payload, then there are many conceivable SABRE based vehicles of various sizes that could be designed - even if they all do come with big H2 turbo pumps.

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