Reaction Engines SABRE engine (Skylon Spaceplane)

[Matej]

Another article directly from ESAs website: http://www.esa.int/Our_Activities/Technology/ESA_test_opens_way_to_UK_spaceplane_engine_investment

Go Sabre! Go Skylon!

 

[carmelo]

Rule Britannia,rule the space?

Of the soyuz, Britons never will be slaves.

 

[Mat Parry]

Bond says ultimately REL does not envision taking on the role of engine manufacturer, but would prefer to stay focused on Sabre’s unique heat-exchanger technology.

I think that's a sensible (and insightful) ambition. let somebody else rule space, we will rule the heat-exchanger market

 

[shockonlip]

Bond says ultimately REL does not envision taking on the role of engine manufacturer, but would prefer to stay focused on Sabre’s unique heat-exchanger technology.

I think that's a sensible (and insightful) ambition. let somebody else rule space, we will rule the heat-exchanger market

And just who do you suppose will take over the full scale engine development and validation/verification?
I don't get the logic of this. It's like P&W saying they developed the gearbox and overall design for a geared turbofan at reduced scale and now wants someone else to do the full up engine development and manufacture.

Perhaps Bond is going to address different levels of heat exchanger technology.
Perhaps some can be adapted to existing engines. Like different levels of
cooling to increase overall engine pressure ratio.

 

[sferrin]

Skylon is a perfect example of the tortoise in the tortoise/hare race. The US's efforts seem to be the hare.

 

[Hobbes]

And just who do you suppose will take over the full scale engine development and validation/verification?
I don't get the logic of this. It's like P&W saying they developed the gearbox and overall design for a geared turbofan at reduced scale and now wants someone else to do the full up engine development and manufacture.

No, it's not. REL have developed the heat exchanger, but they have no experience designing jet engines. Getting into that game would require huge additional investment. It makes sense leaving the jet component of the SABRE to a jet engine manufacturer.

 

[Mat Parry]

Maybe it's a reflection of having a technical mind at the helm and not a business mind, the techie wants to focus on their area of expertise and not dilute their efforts by building capabilities outside their core competance, the Business mind wants to grow the the enterprise to maximise profits.. and rule the world..... Muwhahaha!


Realistically however, Britain (or even Europe) to build a space plane on our own? I think the sun has set on those kinds of ambitions. I hope I'm wrong however because I would travel anywhere on Earth to see that bird fly

 

[Rhinocrates]

It makes sense leaving the jet component of the SABRE to a jet engine manufacturer.

That's the way a lot of business is done nowadays - outsource and co-ordinate the assembly of the final product instead of building up the capital and resources to do it all in-house.


Honestly, I get the willies whenever Elon Musk announces that he's working on a new project - don't spread yourself too thin, I think, know your competence and your resources, get people to help you to do it, don't try to do everything until you know it's working.


Then that's probably why I'm not a billionaire.

 

[shedofdread]

http://www.flightglobal.com/news/articles/uk-spaceplane-shoots-for-2020-flight-test-388456/?cmpid=NLC|FGFG|FGFIN-2013-0723-GLOB

Flight tests of the engine in 2020, eh? Fingers crossed! It would be great...

 

[SteveO]

Reaction Engines expands research project to build full-sized air-breathing engine - http://www.flightglobal.com/blogs/hyperbola/2013/10/reaction-engines-expands-sabre-engine-project-to-finance-full-engine/

Progress!

http://www.reactionengines.co.uk/

 

[FighterJock]

Reaction Engines expands research project to build full-sized air-breathing engine - http://www.flightglobal.com/blogs/hyperbola/2013/10/reaction-engines-expands-sabre-engine-project-to-finance-full-engine/

Progress!

http://www.reactionengines.co.uk/

Let's us hope that Skylon succeeds where its predecessor HOTOL failed. As a member of the British Interplanetary Society I have seen several papers of the Skylon spaceplane and the SABRE engine in their technical Journal JBIS over the years.

 

[sublight_]

From the web site.

At Mach 5 (5 times the speed of sound) the heat exchanger needs to cool air from 1,000°C to minus 150°C, in 1/100th of a second, displacing 400 Mega-Watts of heat energy (equivalent to the power output of a typical gas-powered power station) yet weighs less than 1¼ tonnes.

Anyone care to hazard a guess how that is going to work?

 

[SteveO]

From the web site.

At Mach 5 (5 times the speed of sound) the heat exchanger needs to cool air from 1,000°C to minus 150°C, in 1/100th of a second, displacing 400 Mega-Watts of heat energy (equivalent to the power output of a typical gas-powered power station) yet weighs less than 1¼ tonnes.

Anyone care to hazard a guess how that is going to work?

Clever people will build something clever
A variable intake and a very efficient heat exchanger help. The website should have more detail.

 

[Dragon029]

From the web site.

At Mach 5 (5 times the speed of sound) the heat exchanger needs to cool air from 1,000°C to minus 150°C, in 1/100th of a second, displacing 400 Mega-Watts of heat energy (equivalent to the power output of a typical gas-powered power station) yet weighs less than 1¼ tonnes.

Anyone care to hazard a guess how that is going to work?

Through their patented / secret design. You'd think it to be a scam or hoax, but the simple fact is, their technology has passed all of it's trials so far.

 

[blackstar]

From the web site.

At Mach 5 (5 times the speed of sound) the heat exchanger needs to cool air from 1,000°C to minus 150°C, in 1/100th of a second, displacing 400 Mega-Watts of heat energy (equivalent to the power output of a typical gas-powered power station) yet weighs less than 1¼ tonnes.

Anyone care to hazard a guess how that is going to work?

Through their patented / secret design. You'd think it to be a scam or hoax, but the simple fact is, their technology has passed all of it's trials so far.

So they've gone Mach 5 already?

 

[Dragon029]

No, and I'm sure that'll present a myriad of technical challenges; however, tests this year and last, of the SABRE precooler have demonstrated that it can cool blown 1000C air to -150C in ~0.01 seconds.

 

[Rhinocrates]

The big problem, I gather, was frosting - that is, the buildup of ice as the air was cooled quickly, but they've shown that they can overcome that. That was the biggest potential showstopper apart from reentry, which is a problem for people working on the airframe, not the engine. As Alan Bond has said many times, his focus is on the engine and that's what his company is about, so "Skylon" is really just something that will use SABRE. They are, after all, Reaction ENGINES.

The thing that people need to keep in mind is that SABRE is an air breathing rocket, not a jet, and that Skylon is a launcher that has to compensate for and make use of the fact that Earth has an atmosphere and is not really an aircraft.



The Strathcylde design looks like a better airplane, but its embellishments add weight and make it a lesser spaceship and I worry about that - still, that's only a theoretical project.

 

[Rhinocrates]

For those who are interested, by the way. "Skylon" as a name has this direct inspiration:


http://en.wikipedia.org/wiki/Skylon_(tower)


A magnificent demonstation of tensile structure.

 

[FighterJock]

The big problem, I gather, was frosting - that is, the buildup of ice as the air was cooled quickly, but they've shown that they can overcome that. That was the biggest potential showstopper apart from reentry, which is a problem for people working on the airframe, not the engine. As Alan Bond has said many times, his focus is on the engine and that's what his company is about, so "Skylon" is really just something that will use SABRE. They are, after all, Reaction ENGINES.

The thing that people need to keep in mind is that SABRE is an air breathing rocket, not a jet, and that Skylon is a launcher that has to compensate for and make use of the fact that Earth has an atmosphere and is not really an aircraft.



The Strathcylde design looks like a better airplane, but its embellishments add weight and make it a lesser spaceship and I worry about that - still, that's only a theoretical project.

Any pictures or drawings of the Strathclyde design? So I could compare them.

 

[Mat Parry]

see reply #2


http://www.secretprojects.co.uk/forum/index.php/topic,20566.msg202350.html#msg202350

 

[bigvlada]

From the previously mentioned document

 

[FighterJock]

From the previously mentioned document

Many thanks, I wonder what spaceplane design they will choose to put into production for the SABRE engines. I am torn between the Skylon and the new Strathclyde design.

 

[Nigelhg]

http://www.bbc.co.uk/news/science-environment-27591432

Great article on the economic case and the current state of engine development.

 

[mz]

Nice presentation, contrasting two designs. The AFRL guy has it right, air breathing engines in general better suited for cruise missions, not acceleration like space launch.

 

[sublight_]

At Mach 5, air sucked into the engine goes from 1,000 Celsius to -150 Celsius in one-hundredth
of a second, and a frost control system keeps the moisture from turning into ice and clogging the heat exchanger.

This seems to be the "miracle" part. Has there been any sort of testing to verify they can pull it off?

 

[Hobbes]

Yes, they've done lots of testing, and have submitted their design to ESA for validation. Addressed earlier in this thread (page 6).
http://www.bbc.com/news/science-environment-20510112

 

[athpilot]

Skylon with Orbital Base Station (OBS). Interesting concept! It is a design for an orbital assembly complex in low Earth orbit, functioning as an integral part of a space transportation system and enabling the construction and maintenance of vehicles for the exploration of the Moon and Mars.

 

[steelpillow]

Two things about the Skylon concept worry me.

One is the integration of turbine mode for low-speed atmospheric flight with rocket mode for high speed space flight. AFAIK nobody has yet been able to make a rocket reaction chamber capable of opening its front to ingest air (or, contrarywise, a jet exhaust capable of closing off its inlet to act as a rocket chamber). SABRE must achieve this, or it will end up as a kind of heavyweight concentric hybrid, in which fuel and oxidant flow are switched from the one combustor to the other and it becomes little more than a twin powerplant.

The other is - if all this wonder technology can do so much for the "impossible" SSO, how much could it all do for a two-stage vehicle?

These two thoughts merge if the turbine and rocket are each given their own stage, as a jet-powered carrier mothership with proto-SABRE powered second-stage orbiter. A converted A340-500 with its four Trents should just about hack it. Payload-altitude capability would be substantially more than a pure-SABRE SSO Skylon, and development costs easier to spread around.

 

[merriman]

Your post suggest that there is a non-transitional switch between turbine and rocket mode. However, there is. The third propulsive mode of this engine -- one which would take the load during the air-breathing-rocket hand-over, which incidentally, operates well using air in the near-space, high-speed regeme: the ramjet.

Study the cut-aways of the SABRE engine. Note that the ramjet burners take compressed, hot air from the annular space between air-chiller and engine casing. The ramjet blasts away as the slushy air-liquid oxygen mix is transitioned over to liquid hydrogen-liquid oxygen to the four motors. The ramjet covers the transition period till the shock-cone buttons up.

[img=http://s25.postimg.org/5gnv81m4b/sabre_engine_17.jpg]

They've demonstrated the vital air cooler, now they have to come up with a compound engine injector. Just mechanics. Come on!

Bond and Musk should have a baby!

David

 

[steelpillow]

Your post suggest that there is a non-transitional switch between turbine and rocket mode.

It does? I am not aware of anything on this scale that can switch modes without a transition state of some kind, I didn't think it necessary to spell that out. Shows what I know.

 

[Zoo Tycoon]

Two things about the Skylon concept worry me.

One is the integration of turbine mode for low-speed atmospheric flight with rocket mode for high speed space flight. AFAIK nobody has yet been able to make a rocket reaction chamber capable of opening its front to ingest air (or, contrarywise, a jet exhaust capable of closing off its inlet to act as a rocket chamber).

Not correct; the solid fuel ramjet, i.e SA6/Meteor etc do exactly this as these use a common combustion chamber for both rocket and airbreathing elements.

The Sabre engine ramjet mode is not used on the assent but is available as an emergency abort the event of problem which shutting down the turbo machinery section.

A two stage launcher with a subsonic first stage is more trouble than its worth.;- all the second stage gains is about a 5% improvement from the nozzle outlet pressure matching.

Reaction Engines (and a few years back NASA) have demonstrated a novel nozzle design which negates even this penalty.

 

[steelpillow]

Not correct; the solid fuel ramjet, i.e SA6/Meteor etc do exactly this as these use a common combustion chamber for both rocket and airbreathing elements.

I don't regard a blob of solid fuel as a relevant control mechanism for a fluid-fuelled spaceplane. Nor FYI did Werner von Braun.

A two stage launcher with a subsonic first stage is more trouble than its worth.;- all the second stage gains is about a 5% improvement from the nozzle outlet pressure matching.

Tell that to Pegasus or Scaled Composites. OK SABRE is a little different but for the overall system there are other efficiency gains from using a launch aircraft. The conventional downside is the development cost, however that must be offset against the development cost - and risk, as above - of the full SABRE technology.

 

[Zoo Tycoon]

The solid fuel ramjet (aka airbreathing rocket) uses a variable area injector orifice to introduce the partially combusted gases, i.e a fluid, into the combustion can. This is precisely the component which you claim has never been done before.

The Pegasus 1 is a whole load of surplus /obsolete components cobbled together, i.e. Mx missile rocket motors, an old /unwanted airliner, etc. If all the bits are free or bargin basement prices it's easy to make the business case. Its a very desperate solution with an orbital mass fraction of 0.2% of the runway take off weight.

The Pegasus 2 is predicted to have an orbital mass fraction about the same as a normal expendable rocket i.e about 1-2 %. There is nothing special in this configuration and I don't understand the interest. I guess Scale Composites make money from building bespoke one off and some of the current space business men are not demonstrating a firm understanding of the physics & engineering.

Talking of which, the Space Shuttle sitting on top of a 747 may have looked cool but this doesn't translate to a practical launch solution, remember when on the 747 it had no fuel or payload. The high centre of gravity of the combination had to be reacted by the 747 Nose Landing Gear when braking (the design case will be the max energy RTO). Any commercial airliner is designed to be just about strong enough to perform its intended task and doesn't have spare margins. So to estimate the mass of a piggy back orbital vehicle take the normal passenger payload weight and divide it by the increased moment arm due to extra cg height. My guess is A340, without massive structural modifications, would be able to carry, piggyback, a 20 ton orbiter max. Skylon is designed to have a max take off weight of about 280 tons.

The only real benefit for the horizontal launch is that you don't need a vertical launch pad...... but a Skylon inherently uses horizontal launch ....... so why do anything else?

 

[steelpillow]

The solid fuel ramjet (aka airbreathing rocket) uses a variable area injector orifice to introduce the partially combusted gases, i.e a fluid, into the combustion can. This is precisely the component which you claim has never been done before.

Not at all. SABRE needs to fully isolate the air inlet in order to operate as a rocket in a vacuum. In the ducted rockets that I am familiar with, the valve that you are talking about controls not the air supply but the fuel-rich combustion gas supply, i.e. it operates only in a single combustion mode and is little more than a fuel throttle, and AFAIK it is not required to close fully. I am rather astonished that you have managed to confuse the two.

And like I say, if you don't get Pegasus' and Scaled Composites' business cases, take it up with them. Oh, yes, and why don't you tell Richard Branson he's been conned while you're at it, it doesn't happen to him often (though I did have to take back several copies of the original Tubular Bells release before I got a flawless one, but that was a long time ago).

 

[Zoo Tycoon]

Likewise I'm dumbfounded you believe an air isolation is so difficult. High precision variable flow at high temperature and pressure is challenging by no means impossible.

I think even if Branson hasn't figured it out yet his customers might just have. He's in too deep and I don't believe he's behind Pegasus 2 anyway (P Allen?)

 

[steelpillow]

Likewise I'm dumbfounded you believe an air isolation is so difficult. High precision variable flow at high temperature and pressure is challenging by no means impossible.

It is not just about isolation, it is also about having an efficient, safe and long-lived combustion chamber when the valve is closed combined with an efficient airway at all speeds when it is open. If it was that easy, it would have been done before. In practice, AFAIK engineers have in the past always resorted to dual powerplant installations, though I would be delighted to find that it has in fact been made to work.

I think even if Branson hasn't figured it out yet his customers might just have. He's in too deep and I don't believe he's behind Pegasus 2 anyway (P Allen?)

Branson is the customer for Scaled Composites, he is not involved in Pegasus. My point is that he has a long track record of getting things right. If you think you are smarter than him, I am wasting my time talking to you.

 

[red admiral]

If memory serves, the pre-cooler ground test made use of LN2, not LHe. So I would consider this a necessary initial step towards proving the design, but not yet sufficient to say they have demonstrated it. Helium is a much different working fluid than nitrogen from both a thermodynamic standpoint as well well as from that of simple containment. The real issue with liquid air cycles is can the HEX be made mechanically strong enough to deal with all the stresses imposed on it while keeping its weight to a minimum.

The working fluid in the tests was LHe. The LN2 boiler just serves as a cooler for the LHe thats in the test because its cheaper and easier than a refrigeration plant.

 

[Gildasd]

I'm having a bit of an issue with the thermodynamics/chemistry:

Air is at best 21% O2, so why not use O2 as the cooling medium and plumb it into the combustion chamber somewhere on the right slope of the T-s phase diagram.
Bumping the O2 content above 25% in the process instead of wasting precious He that could be better used in children's balloons?

Edit: Did not spot this:

He is reused. It's a heat transfer medium.
But N2 could still be replaced by O2, it's lower efficiency (−183 °C vs −196 °C) mitigated by it participating in the propulsion and not having the need for the He "boiler" loop.

(The other thing is that the rear lower lip of the engines would not survive re-entry.)

 

[red admiral]

I'm having a bit of an issue with the thermodynamics/chemistry:

Air is at best 21% O2, so why not use O2 as the cooling medium and plumb it into the combustion chamber somewhere on the right slope of the T-s phase diagram.
Bumping the O2 content above 25% in the process instead of wasting precious He that could be better used in children's balloons?

You'll need to put a lot of energy in to the air to cool it significantly to liquefy it and then separate the LOX before using it as a working fluid. The engine in the previous HOTOL concept did something like this but was very heavy.

Remember that the ultimate heat sink for Skylon/SABRE is the LH2 fuel - the diagram you've posted is of the test rig. In the actual engine cycle the LH2 acts as a heat sink for the LHe (which is a closed loop) and is then burnt.

 

[Zoo Tycoon]

I'm having a bit of an issue with the thermodynamics/chemistry:

Air is at best 21% O2, so why not use O2 as the cooling medium and plumb it into the combustion chamber somewhere on the right slope of the T-s phase diagram.
Bumping the O2 content above 25% in the process instead of wasting precious He that could be better used in children's balloons?

You'll need to put a lot of energy in to the air to cool it significantly to liquefy it and then separate the LOX before using it as a working fluid. The engine in the previous HOTOL concept did something like this but was very heavy.

Remember that the ultimate heat sink for Skylon/SABRE is the LH2 fuel - the diagram you've posted is of the test rig. In the actual engine cycle the LH2 acts as a heat sink for the LHe (which is a closed loop) and is then burnt.

Neither HOTOL RB545 or Sabre liquefy the air. This was one of Alan's key break through beyond LACE when he found that it was possible to make the thermodynamics work whilst keeping the turbo machinery the right side of the surge line i.e. an compressor entry temperature of about -180c. This significantly economised on the amount of LH2 required to a point a practical vehicle emerged. The He2 loop was introduced on Sabre to avoid H2 diffusion through the thin walls of the heat exchanger into air which would then posed an ignition risk within the compressor.