Do you think Skylon will be our first completed SSTO?

[tek_604]

That's the worst of it in my mind... Such a great opportunity for the UK to take an authoritative stance on the space market when so far they've done bugger all and it's very likely they won't take it.

Ah, the great what-ifs when you think about British aerospace in general. The UK is the only country to develop a booster, get it to orbit, and then give it up. Thats the sad thing about that whole debacle; the cost was really small, and the engineers worked it all out (took them nearly 30 years, but they did it), only for the government to drop it. Doesn't exactly give a lot of hope for anything to get developed.

All this talk about great things being done in the shed, well, thats great and all (often great ideas come from it), but those shed ideas which got developed into something useful (radar & Colossus come to mind), were given massive backing by the government of the day.

And when the statistics show that the UK space industry is one of the most profitable, and fast growing markets in the UK economy, what does the government do to boost it? Nothing. Oh, they set up the UK Space Agency, another quango which will just eat some more money from the R&D budget, with some paper pushers earning money, considering they didn't pump any money into it. Even the logo cost 50 million quid. Thats the modern PowerPoint generation for you.

It would be great to see a British firm commercially produce the engines but chances are slim on that.

Rolls-Royce should pony up. Its the only company that would make sense to take the chance, and to be fair to RR, they do make some of the greatest engines ever made. Even hardware noone else could duplicate.

[Nibb31]

Absolutely none of Skylon is proven technology. It's a theoretical design, which might work, but is based on margins that are so tight that the whole project can fail because of one small roadblock.

They managed to build a proof of concept of the SABRE precooler in a lab. Although that is a great achievement, there is still a huge difference between a lab bench prototype that uses paper-thin sheets of aluminium and runs in a controlled environment for a few hours and an operational system. Things like reliability, serviceability, and ruggedness have to be included into the design. It has to work under harsher conditions, with vibrations, weather, handling, maintenance...

And this is just a precooler, which accounts for maybe 10% of a totally innovative and unproven engine design.

It takes a decade and billions of dollars for companies like GE or Rolls Royce (yes, British too) to design, build, and certify a new conventional turbofan engine, yet the principles are well-known and they have hundreds of experienced engineers working on the There is only so much 3 blokes in a shed can do.

And that is just for the engine. Skylon's airframe or TPS are also totally unconventional designs. They are reinventing the wheel, which is much more complicated than using proven technology. Although in theory, their designs might work, there needs to be years of studies and prototyping, much more complex than those for an airliner like the A380. In addition, their margins are so thin that if any of their concepts proves impractical, unreliable, or ends up putting on some extra weight, then the whole project fails.

As for the UK having their own space program, I don't think it's realistic to want to start from scratch (even though it has some great companies like BAe, Astrium, and RR). ESA already has a fantastic launcher, a great spacecraft capability and experience, one of the best space facilities in the world, and an advanced space industry. I'd rather see the UK participate more heavily in ESA, maybe by contributing the manned flight capability that ESA is lacking.

Edited June 7, 2013 by Nibb31

[tavert]

I'm not a space technologist or anything (yet), but as it was said earlier, everyone and their mum knows how to build a rocket engine. Most of the components in skylons design have been already. The "oh so exotic" heatshield is loosely based on the SR-71, and already reaction engines have produced examples of the "wonder" material. Pretty much the only thing that has stopped skylon from existing was the precooler, which works, and belongs to RE.

Sabre's not just any rocket engine. See http://en.wikipedia.org/wiki/File:Sabre_cycle_m.jpg

All the turbomachinery in blue and purple is pretty well-understood and reasonably similar to existing rocket engines. The precooler is the heat exchanger with the highest heat flux requirements, which they've been building and testing. But everything in green, the helium loop, including the other two heat exchangers, turbomachinery and control valves, is a brand new type of system without any precedent that I'm aware of. I used to work on air-cycle reverse Brayton cooling systems for aircraft - the pieces are well-understood, but putting them together into a working system is always tricky. Is there enough control authority? Will their valve designs be stable under a wide range of operating conditions and major transients like mode switches? And so on...

I agree with tek_604 that Rolls-Royce would be the logical company to start supporting this. Many of the engineers at Reaction Engines are former RR guys. One wonders whether the company considers space launch a worthwhile strategic direction to invest in...

[tek_604]

As for the UK having their own space program, I don't think it's realistic to want to start from scratch (even though it has some great companies like BAe, Astrium, and RR). ESA already has a fantastic launcher, a great spacecraft capability and experience, one of the best space facilities in the world, and an advanced space industry. I'd rather see the UK participate more heavily in ESA, maybe by contributing the manned flight capability that ESA is lacking.

I did not want it to sound as if the UK should have their own program again. That time is long gone... Actually worries me when I hear about ESA members wanting to launch their own satellites, for example, Germany wanting to launch LEO (which thankfully died the death; I was happy about that, but for other reasons also). I agree with you, the UK should do more with ESA. The funding they do now (I think its the 3rd most, after Germany and France), the UK government and not ESA actually decides where it is spent; the funding is then spent on things which the UK considers to give the best economic payback. This thinking is totally wrong.

[jwenting]

Oh Christ don't...

You're giving me images of the Lapcat/Skylon with that horrible EasyJet orange.

EasySpace!

Oxygen masks, $10 per minute

[Iskierka]

I'm sorry, but -thin- margins? Skylon is not working with thin margins. A thin margin is when 15% increase in mass eats up the entirety of the payload, and that's only thin because many projects might see a 10% increase over design point, or on rare cases around 20%. Go look at the numbers behind Skylon. Payload is a good 25%+ of operating empty weight with the C2 design variant and set to increase with the in-progress D1. Even if the final design sees that outlier weight penalty of 20%, that's still a payload of 5%+ of the OEW, and at the target operating cost, that's still cheaper than anything else on the market.

And this is assuming REL have been quoting numbers the way other entities have, showing the most promising figures they can get away with in a desperate effort to acquire the most funding. REL may be in need of funding, but everything we've seen so far, seems to be pointing at their number quoting being much more sensible. It's probably not off the cards that the final weight may be less than preliminary quotes.

I also see lots of people very seriously underestimating what the work they've done so far represents. A partially-proven precooler that's 10% of the new engine design? Try more like a mostly proven precooler, which all other heat exchangers in the system will be based off. The only major differences between the precooling HE and the helium circuit HEs are scale and the precooler's requirement of an anti-frost system, which, interestingly enough, is basically totally proven now. Other components from the helium loop can be demonstrated via other technologies - maglev electromagnets that use helium for superconductors, MRI scanners, experimental fusion reactors*. Granted, these are not facing the same stresses, except perhaps the reactor, but the precooler's size demonstrates a willingness to use large amounts of inconel, which tends to help.

* Related fact: Alan Bond did actually work on the Joint European Torus for a couple decades, so there should be relevant knowledge of how to make high-capacity coolant systems when facing very high temperature stresses.

All this heat exchanger work has basically proven half of the engine technology which is particularly exotic, if not 3/4. Throw on top the nozzle work done by the University of Bristol for them and research into advanced combustors in pursuit of the SCIMITAR engine and they've done the majority of the work required for individual pieces, they just need to assemble it. The most unproven component of it all is probably the assisting ramjet that has to work with all this thermodynamics-cheating tomfoolery next-door and disturbing its incoming flow.

And specifically, Nibb31, they've already done that kind of ruggedness testing to the heat exchanger. They strapped one of around 20-40% scale to a RR Viper jet, and ran both up to capacity - if that through-flow, vibration, and other general violence caused by doing such doesn't prove its durability, I'm not sure what does until they're funded to build the full thing. They also did all this testing in the rain - condensation from the precooler actually meant every test was in a small patch of it that they made.

The airframe is not an unconventional design, only derivative of current designs to adapt to specific needs of a large entering empty structure. There is also no convention of TPS methods - capsules use a weighty, but small ablative shield. The shuttle only used tiles because it was the only option of the day, and we found out they were a bad idea. Skylon is admittedly trying a new method, but with its low ballistic coefficient, there's no reason to anticipate significant issue yet. Watch that space, but don't go saying it's a major issue to panic over. Also don't go on about reinventing the wheel because every aircraft manufacturer is doing that with every design, what with the move towards composites and integrating them more and more in different components - it's less of a severe obstacle than it might seem.

As might be gathered from the long post, I'm certainly an advocate of Skylon, and have looked in good detail at the work they've done and publicised. I'm certainly aware that it's a risk and there is plenty of work to be done, but the work with the most reason to be doubted has been, and finishing it is more a function of time and money, rather than having to solve many huge remaining issues. And to respond to the obvious reply to that - if there weren't minor details to tidy, it wouldn't take time or money to finish the work. And that applies to any project, yet it still costs several billion to develop an airliner that's just a generational improvement. Everything has small issues.

The issue is, trying to get some people on board, first to fund, and then to manufacture the other components, since their intention is to manufacture the heat exchangers and associated piping/control systems, then to have a real engine manufacturer provide the rest for SABRE, and someone else make the vehicle itself. As mentioned RR would be smart to get in on the engine, EADS/Astrium is likely for the vehicle. Possibly EADS/Airbus if they want to adjust the branding for any reason.

[Nuke]

the ramjets are just a convenient way to reduce intake drag by burning up the surplus lh2 (the precooler needs more lh2 flow to work than the engine can consume) to accelerate any unused intake air (which bypasses the precooler) out the tail end. this just makes the intakes less draggy, as opposed to creating usable thrust, and its all powered by fuel you would have had to vent overboard anyway.

Edited June 8, 2013 by Nuke

[tavert]

I hope you're right, but it's going to be a very expensive undertaking.

Other components from the helium loop can be demonstrated via other technologies - maglev electromagnets that use helium for superconductors, MRI scanners, experimental fusion reactors*.

Components, sure. My argument was not about the components, but about the system integration. None of the examples you quote fly (with the sort-of exception of the maglev I guess), so the mass requirements are not even close to comparable. And none of those system schematics particularly resemble SABRE either. I can assure you from experience, you can start putting components together, each of which perfectly meets their individual design requirements, and run into huge unforeseen problems with system integration, unstable interaction between valves and turbomachinery, etc. Probably the closest comparison to the SABRE engine cycle from a system schematic point of view would be the Integrated Power Package / Power and Thermal Management System on the JSF. It's a dual-mode combination of APU turbine engine and air-cycle cooling system for environmental control packed into the same device. It was also the cause of at least one, if not several, groundings of all test planes in the program.

Edited June 8, 2013 by tavert

[DerekL1963]

I'm sorry, but -thin- margins? Skylon is not working with thin margins. A thin margin is when 15% increase in mass eats up the entirety of the payload, and that's only thin because many projects might see a 10% increase over design point, or on rare cases around 20%. Go look at the numbers behind Skylon. Payload is a good 25%+ of operating empty weight with the C2 design variant and set to increase with the in-progress D1. Even if the final design sees that outlier weight penalty of 20%, that's still a payload of 5%+ of the OEW, and at the target operating cost, that's still cheaper than anything else on the market.

Skylon has no numbers behind it - it has projections based on calculations that are themselves based on assumptions. Treating them as facts is... ludicrous at best.

It's probably not off the cards that the final weight may be less than preliminary quotes.

No, miracles are not off the cards... but they're pretty dang unlikely. The odds of a first-of-a-kind vehicle being built by people who've never built *any* kind of a vehicle coming in underweight and on performance are staggeringly slim. Boeing could barely manage it with the Dreamliner - and they have literally man-millennia of experience.

I also see lots of people very seriously underestimating what the work they've done so far represents.

No, the prevalent intellectual error (by far) in this thread is the diametric opposite - unbounded optimism based on not actually understanding the issues and a prototype of one small component of a very complex engine.

[Fuzzy Dunlop]

Skylon has no numbers behind it - it has projections based on calculations that are themselves based on assumptions. Treating them as facts is... ludicrous at best.

No, miracles are not off the cards... but they're pretty dang unlikely. The odds of a first-of-a-kind vehicle being built by people who've never built *any* kind of a vehicle coming in underweight and on performance are staggeringly slim. Boeing could barely manage it with the Dreamliner - and they have literally man-millennia of experience.

Reaction engines have man-millenia, thats really not that much, Boeing probably have man-eons. That said experience is terrible predictor of project success, SpaceX is flying to the ISS from a standing start about a decade ago (compare that to Lockheed or Boeing). The Soyuz rocket is in many ways identical to the first orbital vehicle ever flown - which Korolev designed less than a decade after the Soviet's captured their first V2.

I think there is still an impression that reaction engines in still 3 guys in a shed, that may have been the case 10 years ago but today the're a fairly significant entity. They recently appointed a new CEO from Morgan Crucible (a turnover ~ £1 billion, FTSE 250 engineering company)

[DerekL1963]

Reaction engines have man-millenia, thats really not that much, Boeing probably have man-eons. That said experience is terrible predictor of project success, SpaceX is flying to the ISS from a standing start about a decade ago (compare that to Lockheed or Boeing). The Soyuz rocket is in many ways identical to the first orbital vehicle ever flown - which Korolev designed less than a decade after the Soviet's captured their first V2.

SpaceX is flying a fairly conventional vehicle, the Sputnik-I booster was based on the (more-or-less) proven R-7 ICBM, and the Soyuz booster built on that. Then you must consider that all the vehicles in question were designed and built by folks with direct and current experience in the relevant technologies.

Reaction Engines has built no functioning engines, let alone a flying vehicle.

I think there is still an impression that reaction engines in still 3 guys in a shed, that may have been the case 10 years ago but today the're a fairly significant entity.

I'm aware they're not three guys in a shed anymore - their size isn't the issue. It's that pretty much everything they're trying to tackle is new. It's that *nobody* has any real/appropriate experience with flown technologies of the type they intend to employ, let alone the integration*. It's that they're trying to leap from nothing to the Concorde. These aren't cause for unbounded optimism.

*And that's often the hardest part, even though it's practically unknown to and ignored by the average fanboy.

[DerekL1963]

Nothing to see here, move along.

Edited June 9, 2013 by DerekL1963
Double post.

[Fuzzy Dunlop]

SpaceX is flying a fairly conventional vehicle, the Sputnik-I booster was based on the (more-or-less) proven R-7 ICBM, and the Soyuz booster built on that. Then you must consider that all the vehicles in question were designed and built by folks with direct and current experience in the relevant technologies.

It wasn't based on the R-7, it was an R-7, Sputnik was effectivley the second long range ballistic missile test (less than 2 months after the first). My point was that the Soviets, who had vitually zero prior experience with rocketry, went from a captured V2 in 1945 to an operational launch vehicle in 1957. Moreover, this first effort has proven more successful than any subsequent design from any other organisation - no matter how much more experienced or well funded.

What I was trying to argue was that organisations don't acctually get much better at managing major projects as they get bigger and older, thus the new guys are no more likely muck it up than the old experinced heads.

[jwenting]

It wasn't based on the R-7, it was an R-7, Sputnik was effectivley the second long range ballistic missile test (less than 2 months after the first). My point was that the Soviets, who had vitually zero prior experience with rocketry, went from a captured V2 in 1945 to an operational launch vehicle in 1957. Moreover, this first effort has proven more successful than any subsequent design from any other organisation - no matter how much more experienced or well funded.

What I was trying to argue was that organisations don't acctually get much better at managing major projects as they get bigger and older, thus the new guys are no more likely muck it up than the old experienced heads.

you have to take the reasons for that failure of NASA into account (Arianespace have a very good booster in the Ariane 4 and V, more reliable than the R7), and that is the lawyer based culture in the US, the bureaucratic nightmare that is the US government (of which NASA is a part), and the active sabotage of the US private space industry (until very recently, things are now getting a bit better at least if you have a contract to supply NASA or the US military) that caused companies to either not even try or come up with weird plans like SeaLaunch (which btw used a Soviet ICBM as its launch vehicle as well).

[tavert]

That's a little silly. There are just as many lawyers and bureaucrats in Europe as the US. When you consider cost and reliability together, Ariane is really quite comparable to Atlas and Delta. What active sabotage? Orbital has been around for many years. Kistler and Roton and others failed on their own. Several had support from NASA and failed anyway.

[Vonar]

As much as I would love to see it fly Skylon won't fly without a lot of government or private sector support and even then it has a low to medium chance of success given the fact that the project has a large amount of untested technologies involved. Also according to the developer's Skylon is projected to cost $12 Billion USD to develop, and each ship will cost $190 Million USD which is quite the price tag for the Brit's, E.S.A, or anyone else to take when you consider the fact that ESA all ready has two of its own rocket classes available for a satellite launch, and the ESA can rent a ride on Russia's Soyuz when it needs to send crew members up to the ISS...

[pyrosheep]

REl just got (5 days ago)permission for a £60 million cheque from the British government towards a high altitude SABRE engine test

http://www.guardian.co.uk/science/across-the-universe/2013/jul/17/sabre-rocket-engine-reaction-skylon

amusingly this was the best link i could find, one implied that SKYLON was a competitor to Virgin Galactic and another said that SKYLON used scram jets (and this was supposed to be an engineering website ).

[Nuke]

the press release from the reaction engines website says that it will be a ground test not a high altitude test. http://www.reactionengines.co.uk/news_updates.html

[3_bit]

The SASSTO was a nice design. It could have made it too. http://en.wikipedia.org/wiki/Douglas_SASSTO If only I could replicate it in KSP....

IMHO the Skylon is a bit complex, but that doesn't mean it will fail. But if it does, that means it will be something Jeb would be proud to see. I still think designs like the SASSTO would be more practical for their simplicity.