Reaction Engines SABRE engine (Skylon Spaceplane)

SteveO

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I've seen the Reaction Engines Ltd Skylon spaceplane mentioned a few times already but I think it deserves it's own thread.

It looks cool and will only cost £10 billion(ish) to develop, so if it wasn't designed in Great Britain 'the land of lost opportunties' it would probably get built ;)

It looks pretty feasible and practical to me, what are your views on it?

Check out the website http://www.reactionengines.co.uk/ and A E Mann's fantastic artwork.
 

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SteveO said:
It looks cool and will only cost £10 billion(ish) to develop

...how many times have we heard something like this...Energia Kliper estimates, for example, were '...just USD 880 mln"...interesting that this chedevre of Russian car industry, for example, was USD 2,4 bln to put into series. Other part of my wants Alan Bond to succeed, of course.
 
flateric said:
SteveO said:
It looks cool and will only cost £10 billion(ish) to develop

...how many times have we heard something like this...

The problem here is that for Skylon to work, a number of currently unbuilt technologies would all need to be built and proven out. It'd suck to go ahead and build the thing only to find out that the engines will invariably stall out at Mach 8.3 due to some as-yet unseen physical principle. Ooops.
 
Interesting, was LACE ever operationally tested in flight ever?
 
flateric said:
Interesting, was LACE ever operationally tested in flight ever?

Not as far as I'm aware. I would not be surprised if some componant testing was done... say, a KC-135 with an air liquifaction rig set up, but I'd be stunned if air was liquified, stored, and then fed into an engine to provide thrust. I'd be freakin' flabbergasted to discover that a complete LACE system that was anywhere near flightweight was ever *built,* much less flown.
 
here Model of Sabre Engine

sabre_model.jpg


and who it sould work

sabre_cycle.jpg


back to LACE
was static Test of that engine ?
and wat of his "evil Brother" NULACE ?
NU stands for NUCLEAR :eek:
 
Whatever we all think of Skylon I think we'll agree this video is pretty good ;D

Skylon mission animation http://www.reactionengines.co.uk/skylon_ops_anim.html
 
SteveO said:
It looks pretty feasible and practical to me, what are your views on it?

At first glance it seems like a no-brainer that an air-breathing vehicle makes sense. A launch vehicle sitting on the pad is 90+ percent propellant, half or more of which is oxygen. If you could get all of that oxygen "for free" from the atmosphere, then the lift-off weight would drop dramatically. Not only would you not need to carry all of that oxygen and tankage for it, but for each kilo of oxygen you didn't carry, you'd need less fuel and hence smaller fuel tanks. Now that you've got a much smaller vehicle (less than half the size), it should be cheaper to operate.

But when you start to think about the details, things don't look so rosy. IIRC, scramjet SSTO designs usually switch from scramjet mode to rocket mode at a few kilometers per second, well below orbital velocity. Things are better than they seem for the scramjet, because a conventional rocket will have burned more than half of its propellant just to get to, say, 1.5 km/s, but we're still a long way from orbit at the stage that a rocket has to take over anyway.

Then there's the fact that launch vehicles try to get out of the atmosphere quickly, to avoid drag losses and heating. A scramjet-based vehicle, on the other hand, must remain in the atmosphere longer. It will suffer higher drag losses and its structure will need to cope with substantial heating.

There is a fundamental limitation on how much the scramjet can help. Getting to orbit is a matter of lifting yourself up to, say, 200 km and accelerating to about 7 km/s. The first takes an energy of about (9.8 m/s2) * (200,000 m) or about 2 MJ/kg. The second takes about 0.5 * (7,000 m/s)^2 or about 25 MJ/kg. Now just think about all of that oxygen that your scramjet scoops up. It is stationary with respect to the earth's surface. Hence, although you don't have to lift the oxygen, you do have to accelerate it to your own speed, just to avoid slowing down, and then you have to accelerate it some more in order to get some thrust out of it. Taking oxygen from the air helps with the 2 MJ/kg of lifting that has to be done to reach orbit, but it doesn't help with the much larger 25 MJ/kg's worth of accelerating that has to be done.

Even though scramjet SSTO designs switch from air-breathing mode to rocket mode at relatively low speeds, the stationarity of the air reduces the efficiency of the engine. Suppose we're burning hydrogen, which gives us an exhaust velocity of about 4,000 m/s in a rocket engine, where the oxygen that is delivered to the combustion chamber is more or less stationary with respect to the chamber. At 4,000 m/s, the oxygen atoms in the exhaust contain a kinetic energy of about 0.5 * (4,000 m/s)^2 = 8 megajoules per kilogram. That's about how much useful energy we're extracting from combustion. In the case of the scramjet, our oxygen come screaming in at, say, 1,500 km/s, so it has a kinetic energy of 1.125 MJ/kg. Now we add 8 MJ/kg through combustion (assuming we can burn as efficiently as in a rocket engine, which is unlikely) to get a specific energy of 9.125 MJ/kg, corresponding to an exhaust velocity with respect to the atmosphere of 4,270 m/s. So, with respect to the vehicle, the exhaust velocity is not 4,000 m/s, but just 4,272 m/s - 1,500 m/s = 2,770 m/s. The simple fact that the oxygen we scoop up is stationary makes our engine less efficient. [NB: This quick-and-dirty analysis ignores the hydrogen in the mass-energy balance, but it's a modest fraction of the total mass.] The faster we go, the worse this problem gets. The problem will be worse, too, if we use a hydrocarbon fuel, which has a lower exhaust velocity. And this ignores the fact that the air we scoop up is mostly nitrogen, not oxygen. I know there are ways of dealing with the nitrogen, but they add complexity and inefficiency.


IMHO scramjets are interesting and deserve further research. But for SSTO applications, scramjet technology will have to be very much more mature than it is now to be worth the trouble.
 
Proponent said:
The simple fact that the oxygen we scoop up is stationary makes our engine less efficient.
Are you confusing ramjets and scramjets? Throughflow in a scramjet engine is supersonic, to avoid the heat and pressure generated as compared to slowing to subsonic in a ramjet.
 
Simon666 said:
Proponent said:
The simple fact that the oxygen we scoop up is stationary makes our engine less efficient.
Are you confusing ramjets and scramjets? Throughflow in a scramjet engine is supersonic, to avoid the heat and pressure generated as compared to slowing to subsonic in a ramjet.

My quick-and-dirty analysis is the best-case scenario, in which there are no losses due to slowing of the inflow as it passes through the engine. As you point out, scramjets will operate closer to this limit than ramjets can, but they are still subject to it.
 
Interesting news in this month’s Spaceflight

The British spaceplane developer Reaction Engines celebrated its 20th anniversary in mid-August and revealed that it is planning to fly its Skylon spaceplane for the first time in 2018.

Also

Preliminary studies have begun to develop a larger version of the Skylon design. Skylon D1 will be capable of carrying a 25 percent larger payload into orbit than the current design. It will also be approximately 340 tonnes in weight at take off compared with the current 275 tonnes.
 
The SABRE engine is neither a Ramjet nor a Scramjet - "The SABRE engine is a combined cycle engine which air-breathes like a jet engine but with a pre-cooler heat exchanger in front of the turbine compressor. There is a secondary bypass ramjet in the nacelle, but this is subsonic combustion and so not a Scramjet."

The key to making it work is the heat exchanger, and the associated frost control. The engines can't stall at M 8.3, as they transition from air breathing to rocket mode at about M5.

They've been testing the pre-cooler heat exchanger at their test facility, and it's looking very good indeed. The only other major hurdle was demonstrating that a rocket can be cooled with LOX, and there's just been a successful test by EADS Astrium. They're currently refining the the design from the C1 config that is in all the illustrations, to the D1. Even I haven't seen that yet, but it will apparently be sufficiently different that you won't have to be a rivet counter to see the changes.

Surely it makes more sense to invest in technology like this - unproven or otherwise - than going back to building yet another missile and capsule system? Whatever happens, it'll create something new, or new ways of thinking about these problems at least. And you know what, it might just work... imagine that! A proper reusable system, on demand, with a decent payload that'll make access to space truly routine. I'm so disappointed that someone like Elon Musk with all his cash, has the 'vision' to build... a missile with a capsule. Here - build this instead, and change the world forever.
 
aemann said:
Surely it makes more sense to invest in technology like this - unproven or otherwise - than going back to building yet another missile and capsule system?

It depends greatly on what your end product and schedules are. if your goal is to have a relatively inexpensive manned launch system within a decade, then clearly you want to go with known technologies. If your goal is to spend lots and lots of money in the hope that several decades down the line you *might* develop a new piece of technology that will do something that simpler tech already does, then hey, by all means, invest in the unproven.

Rocket engines work. SABER engines, scramjets, liquid air cycle engines, MHD ramjets... don't. Not yet at any rate. And there's no good evidence that spending X millions will make them work, and even less evidence that after all that time and expense you'll have a technology that will make operations any cheaper, never mind procurement costs.
 
As I understand it Reaction Engines' business plan isn't that they need Skylon to be developed and successful to generate any ROI. Instead they're looking to be a heat exchanger technology company and so could be starting to make a return quite soon.

True the company has already been going for many years, but it's a small company and has been generating some income. So I'd guess that the private investment so far is a lot less than Elon Musk has put into SpaceX. Probably more like the amount John Carmack has invested in Armadillo?

More details of their recent work, referred to above, and a new video are in their latest newsletter: http://www.reactionengines.co.uk/news_apr10.html
 
that little bit of topic

but it's sooo hilarious
Bilion Dollar project to put man on Mars, only to beaten by geeks
index.php
 
SteveO said:
As much as I love Skylon and anything like it, I can see wormhole/Compression Space Transport technology arriving before any hardware gets built ;D

I know what you mean ;)

As I see it, a big issue for obtaining funds to even attempt to build Skylon is lack of a roadmap from proving basic technologies (such as current heat exchanger work) to the billions needed for a full vehicle. Maybe Reaction Engines have such a plan and it's too commercially sensitive to discuss. But like you I can't see it happening without some smaller - and useful - intermediate development steps.

P.S. That's pre-supposing it's all technically achievable, which isn't a universally held view ...
 
Japan "baraban pre-cooler" followed recently in India with Russian assistance. Sabre is deeply cooled rocket not a scram or a ram converts to all rocket around mach5-6 then pitch up to orbit. And fact is Japan and India are way ahead of Reaction deep cooled technology.
 

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airrocket said:
Japan "baraban pre-cooler" followed recently in India with Russian assistance. Sabre is deeply cooled rocket not a scram or a ram converts to all rocket around mach5-6 then pitch up to orbit. And fact is Japan and India are way ahead of Reaction deep cooled technology.
This sounds WAY too familar... I'm thinking I've heard of this before in relation to the RASCAL program. I seem to recall a report showing a "deep-cooled turbo-rocket" called the "KIL-N" cycle I think?? Basiclly it used an RL-10 engine fed by LH2 and Liquid Air drawn from a set of compressor intakes and heat-exchangers...

I'll see what I can find again.

Randy
 
Re: Skylon - space transport

edwest said:
I would let to get the learned opinions of the members about this proposal:

My opinion: the editor who came up with the title is a MORON.

"spaceplane that will take tourists into orbit at five times the speed of sound"

Gah.

"The Skylon’s innovative engine uses propulsion to reach the edge of the Earth’s atmosphere..."

Astounding! It uses propulsion!
 
The Daily Mail article listed above is a rehash of http://www.theengineer.co.uk/in-depth/analysis/out-of-this-world/1004713.article.

Reaction Engines also recently made a submission to a parliamentary select committee on the new UK Space Agency (see http://www.publications.parliament.uk/pa/cm201011/cmselect/cmsctech/memo/space/m09.htm).

The submission contains the following interesting titbit:

Since the [UK Space] Agency was formed the main interaction with Reaction Engines has related to the organising of a major international review of the SKYLON spaceplane to be held on 20th to 21st September. This review will host over 100 experts from around the world to assess the economic and technical aspects of the SKYLON concept. The outcome of this Review, supported by an evaluation from the European Space Agency will give the UK Government confidence that, should further support to project be given, it will be on the basis of a thorough assessment.
 
Reaction Engines' September newsletter includes the following about the recent review:

[quote author=http://www.reactionengines.co.uk/news_sept10.html]
On 20th and 21st September, the UK Space Agency held a System Requirements Review on the commercial and technical capabilities of SKYLON at the International Space Innovation Centre at Harwell, England. Approximately ninety invited experts attended the event venturing from various European and global nations including the USA, Russia, India, Japan and South Korea. In the months leading up to the Review, three engineers from the European Space Agency (ESA) were seconded to REL in order to investigate our technology, methods and analysis. ESA will provide the UK Space Agency with an official report on the Workshop within in the next month.

The preliminary results of the event are indicative that the majority of the attendees consider SKYLON to be a viable concept. Responses to questions on the project provided a clear and honest overview of the programme. Dr Constantinos Stavrinidis, Head of Mechanical Engineering at ESA, gave the closing address and commended the competence of REL and its SKYLON concept.

REL hopes that the feasibility of the SKYLON programme is no longer in doubt and that the commercial and technical aspects of the project are well understood and recognised. Over the coming months, discussions with government, industry and private investment are due to take place and REL looks forward to further progressing SKYLON.

The UK Space Agency’s press release for the event is available at http://www.ukspaceagency.bis.gov.uk/19661.aspx?pf=1

Recently, one of the recurring questions has been the degree of government involvement in the SKYLON development. To date, the public contribution stands at 15% with the remaining 85% provided by private investment. REL intends SKYLON to remain as commercial a programme as possible.
[/quote]
 
I had a looong talk with the Reaction Engines representatives, a very usefull one, so when I will have some free time to spare, I will write some extract of it.
 

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EDIT: Oh found already some spreadsheet materials on their homepage so my questions have been partly answered at least.
http://www.reactionengines.co.uk/pdf_documents.html
 
Matej said:
I had a looong talk with the Reaction Engines representatives, a very usefull one, so when I will have some free time to spare, I will write some extract of it.
Thanks Matej, will look forward to it.

Nice pic of the SABRE, lots to get right and lots that can go wrong there!
 
Oh, wow ! That's a blast from the Golden Age of rocketry !!

FWIW, I think the station should be a polygonal toroid so that segments would lack compound curves and *would* fit in cargo bay...
 
Nik said:
Oh, wow ! That's a blast from the Golden Age of rocketry !!

FWIW, I think the station should be a polygonal toroid so that segments would lack compound curves and *would* fit in cargo bay...

that is inflatable toroid segments (see concept art)
 
Nik said:
FWIW, I think the station should be a polygonal toroid so that segments would lack compound curves and *would* fit in cargo bay...

...There have been concepts that allow for compound curves in structures that can be fit in a conventional cylindrical cargo shroud/bay. They involve stacking smaller segments rotated 180 degrees from each other, thus aligning them along one axis as a cylinder. When orbit has been achieved, the whole stack is removed, the segments rotated, and as much as a 1/4 arc of a complete toroid results. Note that a 1/4 arc required a serious lift booster, and the more conservative concepts I've read about called for arcs of only 1/6 or 1/8.

Wish I still had those papers that discussed these concepts. The diagrams were actually quite detailed in the stacking and deployment phase.
 
Reaction Engines have a key test of their precooler technology coming up in June. But what I find most interesting about the following report is the claim that they have $350M worth of funding lined-up contingent on the precooler working!

[quote author=http://www.space.com/11414-skylon-space-plane-british-engine-test.html]
Big Test Looms for British Space Plane Concept

SAN FRANCISCO — A huge, unmanned British space plane is on pace to start launching payloads into Earth orbit in less than a decade — provided it can pass a crucial engine test in June, its designers say.

[...]

The atmospheric air whooshing into the SABRE engines at high speeds would be extremely hot. But for the engines to work efficiently during the air-breathing stage, that air needs to be cooled substantially — down to about minus 238 degrees Fahrenheit (minus 150 degrees Celsius) — before being compressed and reacted with the onboard hydrogen.

That's what the big test in June is for. Skylon engineers have developed a new "precooler" system to do the job. The system will get its first big test in the June trials.

If the precooler works, investors will chip in another $350 million, helping take the Skylon project to another level of development. That next phase would likely see vehicle design completion and a full engine demonstration by 2014
[/quote]
 
Skylon Spaceplane pre-cooler

IIRC, *if* the pre-cooler works, then they'll license it to Euro-consortium who want to build an antipodal Mach-5 jet liner aka 'Lapcat'. No rockets, pure air-breathing, but Europe to Australia in five (5) hours flat...

The cash-flow from that bootstraps Skylon development, first just air-breathing to Mach 5 for heat-soak and structural / handling / control stuff, then upgrade to full SABRE engines and push envelope towards orbit...

Sounds like a plan...
 
I thought Lapcat was just an EU funded study, not something that would ever be built! Who's putting up the billions required to fund development?!
 
Europe to Australia in 5 hours? ROFL. Who wants to go to Australia any way? [Maybe some would like to come back ...] Seriously, there are what ... 20 million people in Oz? Not exactly a mass market.

As for Mach 5 and the rest - has no one learned anything from Concorde? Supersonic flight over land is a big no no.
 

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