Quote from: Star One on 03/30/2016 05:20 pmIt was my understanding that none of this promised £60 million had been so far received?From the report, it would appear your understanding is correct:Quote Mark Wood: "Let me give you a local example. Reaction Engines received a tremendous boost when itwas 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 westill have not seen any of those funds flowing into the company. Potentially, it is a missedopportunity in that it has given our competitors an extra three years to try to find ways tobeat our engine."
It was my understanding that none of this promised £60 million had been so far received?
Mark Wood: "Let me give you a local example. Reaction Engines received a tremendous boost when itwas 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 westill have not seen any of those funds flowing into the company. Potentially, it is a missedopportunity in that it has given our competitors an extra three years to try to find ways tobeat our engine."
I wonder why the government have suddenly got cold feet on this, Treasury meddling?
Quote from: Star One on 03/30/2016 05:20 pmIt was my understanding that none of this promised £60 million had been so far received?I guess we would all agree the UK government should honour their £60 million promise to RE.How about this forum creating a petition we could present to HM government.I fully understand if the management of this forum do not wish to dip their toes into politics, but do we just say nothing and allow government to play politics with the aero space industry.
Has anyone looked at the possibility of applying tri-propellant technology to the SABRE? So the hydrogen is the main propellant taking up most of the volume of the airframe, and its still a big airframe even with reduced sizing of the oxygen tanks. So what about using a tri-propellent, use kerosene with the air breathing initial stage, then switch over to LH2 for the rocket portion where it would have a bigger advantage? Means you minimise storage size and therefore airframe mass? Plus that tank would need less insulation on ascent as its not cryogenic?
What this article neglect to say is that the whole engine can be tested and develop on the ground until all of the main problems, such as wear and tear of the combustion chambers are solved.
An well it not surprising the main criticism of Skylon come from people who are pursuing Scramjets, surely most funding for that dream would cease.
A scramjet can go up to Mach 10.
Mach 5 you can do with a turboramjet, to my knowledge.
I'll note that people who love the SCRamjet concept never talk about it's T/W or the very large system needed to get it up to operating speed.
It took me years to discover the current expected T/W for a SCRamjet is about 2:1. That's less than the combined J58/nacelle combination (and the combination was key to making the system work) for the SR71 in the mid 1950's.
6 decades of effort (starting roughly in 1960 at Johns Hopkins APL) has produced this.
Historically fixed geometry ramjets have been good for a an operating Mach range of about 3 IE M1-M4 M2-M5 at most disregarding the weight of the rocket (including propellant) or air breathing engines to get it there.
SABRE design (as it was planned to from day one) covers the whole range from 0 to M23. The downside is it's poor (but only by rocket standards) T/W ratio (which is 50% better than state of the art turbofans).
SABRE buys a huge propellant tank (provided by the airflow through it) and that makes it's relatively poor IE T/W ratio 7x better than SCRamjet, performance, coupled with it's excellent air breathing Isp good enough to get the job done.
This was the original REL concept for a Nacelle Test Vehicle:
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.
Quote from: RanulfC on 03/31/2016 03:54 pmThe 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.
Quote from: SICA Design on 03/30/2016 08:37 pmThis was the original REL concept for a Nacelle Test Vehicle:Would seem to be about the right size but mass looks really, really low... ...Given the configuration of the SABRE compared to the more integrated DRACO RBCC I suspect it would probably be EASIER to modify the D-21 to house a small scale SABRE prototype. If of course the SABRE can be scaled down sufficiently.Randy
The scramjet research and the people involved have no sensible bearing on space launch, so why the hell ask them to comment on SABRE?
Quote from: oddbodd on 03/28/2016 03:47 pmThe scramjet research and the people involved have no sensible bearing on space launch, so why the hell ask them to comment on SABRE?Scramjet researchers may be biased. But so might the people at REL. Scramjet researchers are experts on propulsion at these speeds. There's basically just them and REL. Both could potentially have some bias, but if you want a perspective from outside REL, there's nobody better to give it than scramjet researchers.Whether the goal is space launch or missiles, it's still propulsion at hypersonic speeds.So, it makes sense to be wary of what scramjet researchers say about Skylon, and keep a critical frame of mind, but not to dismiss it out of hand.
The technology is scalable. Last time I asked, REL had not run into any upper limit, and there's no real reason you couldn't make it a bit smaller if that would fit the market better.But if you try to make it a lot smaller, you run into problems. Alan Bond has noted that a subscale development engine like the one they were planning originally would have issues with the extreme speed of the hydrogen turbopump (~300krpm or something), which would cost quite a bit to develop. Hence their eagerness to go to full scale on the engine prototype when it looked like they'd have a chance to do so.