By Steve Morris, 4 Dec 2012
How many times have you watched a sci-fi film in which a spaceship arrives at some planet and descends to the surface to land?
Astonishingly, the technology to enable this to happen didn't exist until last week when Reaction Engines Limited, a British company based in Oxfordshire completed testing its SABRE engine.
SABRE is a revolutionary new kind of engine that Reaction Engines hopes will one day power its Skylon spaceplane. Skylon is an aircraft that will be able to fly at 5 times the speed of sound and fly directly into space, like a rocket.
The SABRE engine
The problem with existing rockets is that they have to carry their own supply of liquid oxygen, in order to burn their rocket fuel. This onboard supply of oxygen is extraordinarily heavy, which means that rockets have to be extremely large and use throw-away stages in order to get into space. It takes all their fuel to leave the atmosphere, so there's no way they can return to Earth under their own power. NASA's Space Shuttle used external rockets which were jettisoned before reaching orbit and then it had to glide back to Earth when its mission ended.
By contrast, jet engines use oxygen from the atmosphere to burn their fuel, making them much more efficient than rockets. But of course this means that they can't fly into space.
SABRE (Synergetic Air-Breathing Rocket Engine) is a new concept that combines the best features of rockets and jet engines. In the atmosphere, it takes in air and compresses it to burn its liquid hydrogen fuel. Once it reaches space, it uses an onboard supply of liquid oxygen. When it returns to Earth it starts breathing air from the atmosphere again, so it can land under its own power.
The efficiency gains from using an engine of this type in a reusable vehicle are enormous and should slash the cost of space exploration.
You might think that building an engine that could do this would be easy and obvious, but in fact the technological hurdles are immense.
In air-breathing mode, the air must be compressed to around 140 atmospheres before injection into the combustion chambers which raises its temperature so high that it would melt any known material. SABRE avoids this by first cooling the air using a pioneering design of heat exchanger until it is almost a liquid. Special rocket nozzles and air intakes have also been developed as part of the SABRE programme.
The European Space Agency (ESA) completed its testing of the SABRE engine on 28 November 2012 at Culham in Oxfordshire - an event described as "the biggest breakthrough in aerospace propulsion technology since the invention of the jet engine."
The Skylon spaceplane
The Skylon spaceplane is an unpiloted, reusable spaceplane that makes use of the SABRE rocket engine. Skylon will be capable of transporting 15 tonnes of cargo into space and will be able to take off from a runway, fly directly into Earth orbit and return for a runway landing, just like an aircraft. It is expected to cost around one tenth of a conventional single-use rocket.
We think it looks quite a lot like Thunderbird 1, and that's surely no bad thing.
In air-breathing mode Skylon will be able to fly at speeds of up to Mach 5.5 and a height of 25 kilometres. Compare this with the world's current fastest plane, the Lockheed Blackbird, which can reach a similar height with a maximum speed of Mach 3. Once it has reached this height the SABRE engines will transition to rocket mode in order to accelerate beyond the atmosphere and reach orbital velocity, Mach 25.
Skylon will be built from a carbon fibre reinforced plastic fuselage and a fibre reinforced ceramic shell. This external shell will measure just 0.5mm thick. The spaceplane will measure a length of 82m, with a wingspan of 25m.
Reaction Engines is now looking to raise the £250m needed to complete the next phase of development.
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Comment by Mr. Wes D.
on 20th Jul 2015
I am not an engineer nor an expert but am trying to design a chemical rocket propulsion SSTO HTOL but in this case the secret it does not use just one single burn into orbit but uses three on/off rocket engine burns into Earth orbit. This seem to be more effiecent and support using LOX/LH2 propellant too. If any one is interested pl
Comment by himel009 from bangladesh on 4th Dec
Comment by John E.Taylor from England, U.K. on
4th Dec 2012
Well done Reaction Engines Ltd. but please keep the designs out of the public and the rest of the world's pockets and make profit for REL to benefit ENGLAND for a change.