spaff billions of quid
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?
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,
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..."
Just wanted to emphasise this quote:(Via momerathe)QuoteReaction 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 amazing peoples 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.
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?
May be they are now just planning to buy a off the shelf LH2 turbopump, like the use on the Vulcain engine?
Quote from: knowles2 on 10/17/2016 03:26 amMay 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.
Yes there is and you in fact point out there are BUT point out they may need modification
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.
Quote from: RanulfC on 10/17/2016 04:21 pmYes 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.QuoteRL-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 ?
Quote from: john smith 19 on 10/19/2016 03:03 amQuote from: RanulfC on 10/17/2016 04:21 pmYes 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.QuoteRL-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.
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
Quote from: t43562 on 10/29/2016 07:24 amThis 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/140271208The 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?
So I do wonder what reception SABRE will have when it is demonstrated.