Bristol Spaceplanes

royalistflyer

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Forget Virgin and its glitzy approach, the current setback is big, but in my view the overall project concept is a dead end, and possibly basically flawed. It has a relatively short-term end in view, typical of the people behind it. If you want to see a sensible, workable reusable space aircraft project, go here http://bristolspaceplanes.com
 
Re: SPACEPLANES

Did Bristol Spaceplanes already send something in space or is it still CGI rendering and animations, bench tests and flying models?
 
Re: SPACEPLANES

Cool. As far as I can tell, there is no real hardware yet.

I find it interesting that the SSO - Single Stage Orbiter - concept is at last being abandoned. Remember HOTOL?

I have a sneaking suspicion that the inspiration behind this project is that HOTOL showed how hard SSO really was and that sub-orbital would be a lot easier. Funnily enough, back then I had an article and some drawings published which suggested launching HOTOL from a subsonic carrier plane. It is good to see that the "we can do SSO with new technology" hype is at last fading and Sänger's original "look what all that new technology can do for the multi-stage vehicle" pragmatic approach is returning. The Spacecab concept in particular looks very close to some of Sänger's design studies.

And I do think you are being unfair to Virgin. Richard Branson has said that his sub-orbital toy is just the first step on a long road, and that he is focusing firmly on that first step. If "a light plane with supersonic aerodynamics and a rocket engine" could really make sub-orbital space at a viable cost, why would all those Scaled Composites simulations have come up with a two-stage solution?
 
Go to reactionengines.co.uk and you will see that the successor designs to HOTOL are far from dead. Reaction Engines have produced a spectacularly successful revolutionary engine that makes orbital flight a real possibility. Both the UK government and the European Space Agency have poured money into this highly technical project which has found answers to seemingly insuperable problems.
 
royalistflyer said:
Go to reactionengines.co.uk and you will see that the successor designs to HOTOL are far from dead. Reaction Engines have produced a spectacularly successful revolutionary engine that makes orbital flight a real possibility. Both the UK government and the European Space Agency have poured money into this highly technical project which has found answers to seemingly insuperable problems.

Agreed. HOTOL, the concept, is not dead. And they got the heat-exchanger to work -- a technical break-through which was the one enabling piece of the puzzle which, now, makes the rest of the engine doable.

At the very least this could get our jet planes up to Mach-4.

Go get 'em, Mr. Bond
 
HOTOL is not just its powerplant. SABRE's integrated air liquefiers are just one of the new technologies needed to make it work at all, never mind carry a payload worth spitting at.

The SSO spaceplane concept has other flaws. It carries into orbit all the dead weight of a retractable undercarriage capable of supporting the fully-laden machine, along with the big wings needed to get the whole lot off the ground at a realistic takeoff speed. With minimal range in atmospheric cruise, the window of available orbits for minimal fuel burn would be restricted. Both HOTOL and the Reaction Engines SKYLON share these same flaws.

A carrier mothership would have reduced or eliminated these flaws, greatly increasing the maximum payload and/or allowing a smaller, cheaper HOTOL. It also increases the range of atmospheric flight, allowing more optimal positioning of the spacecraft to reach its designated orbit with minimum fuel burn. Bristol Spaceplanes propose a similar two-stage design, though they place the separation point farther into the flight trajectory than I did.

I didn't find reference to Bristol's preferred rocket fuel, but a mothership could also allow the inflight topping-up of an orbiter's liquid hydrogen tanks to replace the fuel that boils off during the early stages of flight. That alone allows an environmentally-friendly orbiter to be 10% lighter - or some of that 10% can be converted to extra payload.

Just think what a two-stage vehicle could do for the payload of a SABRE-powered orbiter. Or, think what SABRE engines could do for the operating economics of the Bristol Spaceplanes. I suspect that is the ultimate vision.
 
Last week at the Von Braun Symposium in Huntsville there was a panel on advanced propulsion. Mark Lewis, who is an expert on hypersonics, spoke about air-breathing hypersonic proposals over the decades. Although he is a proponent of hypersonics research, he's also not a starry-eyed enthusiast and pointed out numerous drawbacks and limitations to the technology. He was asked about this project and the engine. He said that if you had asked him about it five years ago he would have essentially said it was all bunk. However, he said that he has changed his assessment based upon their recent reported breakthrough. He now thinks that it has promise.

He did add that so far their technology is proprietary and it has not been evaluated by outsiders, so he doesn't know if they actually achieved what they claim. He also added that there's a big difference between proving it in the laboratory and an in-flight operational demonstration. But he didn't immediately shoot it down as ridiculous.
 
blackstar said:
He did add that so far their technology is proprietary and it has not been evaluated by outsiders, so he doesn't know if they actually achieved what they claim. He also added that there's a big difference between proving it in the laboratory and an in-flight operational demonstration. But he didn't immediately shoot it down as ridiculous.

This isn't correct as REL's work has been separately evaluated by ESA, including the most recent heat exchanger test series.

Currently AFRL, NASA and DSTL are evaluating the project.

Its good to remember that unlike a scramjet - it is actually possible to bench test the SABRE engine on the ground.

A carrier mothership would have reduced or eliminated these flaws, greatly increasing the maximum payload and/or allowing a smaller, cheaper HOTOL. It also increases the range of atmospheric flight, allowing more optimal positioning of the spacecraft to reach its designated orbit with minimum fuel burn.

These are all good points, but completely overlook cost. A reusable SSTO will be cheaper if you can get a good enough payload fraction e.g. as enabled through the SABRE engines. However, given the high development costs and the newer rockets from SpaceX and Ariane, I don't think they can make it cheap enough.
 
red admiral said:
A reusable SSTO will be cheaper if you can get a good enough payload fraction e.g. as enabled through the SABRE engines. However, given the high development costs and the newer rockets from SpaceX and Ariane, I don't think they can make it cheap enough.
There is a tradeoff here between development cost and operating cost. Assuming that a single SSO is cheaper to develop than a carrier plus an orbiter, it will carry less payload per buck in operation. And is that assumption justified anyway? We are not comparing like with like. One carrier plus one orbiter using current technologies have a relatively predictable cost. The SSO is not just the airframe, not even a new airframe and a new engine, it is also a brand new and as yet unproven engine concept. Worse, it has a hidden commercial cost in that it will take longer to develop, losing money all the time that its conventional-tech competitor could have already been earning. The total development cost of that package could turn out a lot higher than just a plane and a shuttle - and it is a higher-risk proposition too.
 

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