The rocket that thinks it's a jet
A reusable space plane that can take off from a conventional aircraft runway, carry over 12 tonnes into orbit and return to land on the same runway, could be less than a decade away thanks to engineers at Bristol University and a €1 million award by the European Space Agency (ESA).
The project, led by space propulsion experts, Reaction Engines Limited (REL), is part of a joint public and private multi-million pound research programme. The technology, developed by a European team of experts including academics from the University’s Department of Aerospace Engineering, is for the SABRE air-breathing rocket engine, which will power the ‘SKYLON’ space plane.
The SABRE is a unique hybrid engine that can ‘breathe in’ air when in the atmosphere, like a jet engine, and become a rocket engine when in space. In air-breathing mode, air is first cooled by a revolutionary heat exchanger pre-cooler before being compressed and fed to the rocket engine to be burnt with hydrogen fuel. When in rocket mode the hydrogen is burnt with liquid oxygen.
Alan Bond, Managing Director of REL, said: “Traditional throw-away rockets costing more than a $100 million per launch are a drag on the growth of this market. The Holy Grail to transform the economics of getting into space is to use a truly re-usable space plane capable of taking off from an airport and climbing directly into space, delivering its satellite payload and automatically returning safely to Earth.“
Years of planning and research by REL on the ‘SKYLON’ vehicle and its unique SABRE air-breathing engine mean that we have an inside track on realising this goal. SKYLON could reduce the cost of getting into space by a factor of ten.”
The demonstration programme will look at three key areas in the engine.
The first area, conducted by REL, concerns the revolutionary pre-cooler that cools the incoming air as it enters the engine. During the programme a test pre-cooler will be constructed using the actual module design for the flight engines. This will be tested on the company’s B9 jet engine powered experimental facility at Culham in Oxfordshire.
The second area is the cooling of the combustion chamber, where the propellants are mixed and burnt producing water vapour at around 3,000oC. The SABRE engine uses the air or liquid oxygen as the cooling fluid – a key and unusual design feature as most rocket engines use the hydrogen fuel for cooling instead. EADS Astrium and DLR in Germany will be conducting this work using demonstration chambers fired at the DLR Lampoldhausen facility.
The third area, led by Dr Neil Taylor in the University’s Department of Aerospace Engineering, will explore advanced exhaust nozzles that can adapt to the ambient atmospheric pressure. This follows on from the successful STERN (Static Test of ED Rocket Nozzle) test rocket programme that was conducted last year. As part of the ESA contract a new water-cooled chamber will be constructed and test fired.
Dr Taylor said: “It’s excellent news, and allows us here to build on the extensive successes we had with the STERN project. If successful, the impact the overall project will have is enormous, and it's really exciting to be in at the beginning of a potential revolution in the space world.”
The demonstration programme has the objective of removing all the outstanding technical concerns on the SABRE engine. This will pave the way to a full engine development programme as part of the overall development of SKYLON. Cheap, easy and reliable access to space is critical to the development of the global space market, now worth more than $150 billion a year worldwide.
Lord Drayson , Minister for Science and Innovation, said: “This is an example of a British company developing world-beating technology with exciting consequences for the future of space. It is fantastic that Reaction Engines, the British National Space Centre and ESA have successfully secured this public-private partnership arrangement and I look forward to seeing how the project progresses.”
Reaction Engines Limited, a firm in Oxford, United Kingdom, has recently been awarded €1 million by the European Space Agency. This money is to be used for development work for the firm's SABRE engines.

The SABRE engines are for a reusable spaceplane that it is intended to be able to travel into space and return completely intact. 

Reaction Engines Limited says the Skylon plane could be in service within 10 years. When in service it would be intended to be regularly carrying up to 60 passengers into orbit much more cheaply than today.
Diagram of the Reaction Engines Skylon
The cash will be used to test a precooled jet engine that would cool the very hot air entering the engines and should permit the aircraft to fly more economically, like a jet plane. The plane will fly through the air to 26 km (85,000 feet) altitude and five times the speed of sound before using rockets to push the aircraft the rest of the way to orbit.

The BBC says that other aspects of the Skylon design will be investigated by EADS Astrium, the German space agency (DLR) and the University of Bristol.