UK-based Reaction Engines Limited (REL) – the firm behind the ‘Sabre’ air-breathing rocket engine, which will power the Skylon spaceplane – is currently working on various tests and demonstrations that will bring this spacecraft one step closer to reality.
But what is Sabre?
The Sabre is a unique hybrid engine that can “breathe” 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 before being compressed and fed to the rocket engine, where it is burnt with hydrogen fuel.
When in rocket mode, the hydrogen is burnt with liquid oxygen.
“Traditional throw-away rockets – costing more than $100 million per launch – are a drag on the growth of this market,” said Alan Bond, Managing Director of REL.
“The Holy Grail to transform the economics of getting into space is a truly reusable spaceplane capable of taking off from an airport and climbing directly into space, delivering its payload and returning safely to Earth,” he explained.
Testing all systems
In tests, the spacecraft builders will look at three key areas in the engine.
The first area, conducted by REL, concerns a new pre-cooler that cools the incoming air as it enters the engine.
During the programme, a prototype 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 in the UK.
The second area is the cooling of the combustion chamber, where the propellants are mixed and burnt, producing water vapour at around 3,000 degrees Celsius.
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.
UK-based EADS Astrium, an aerospace subsidiary of the European Aeronautic Defence and Space company (EADS), will conduct this work along with DLR, Germany’s national research centre for aeronautics and space, using demonstration chambers fired at a DLR facility.
The third area, led by the University of Bristol, will explore advanced exhaust nozzles that can adapt to the ambient atmospheric pressure. Also, a new water-cooled chamber will be constructed and test fired.
“Years of research by REL on the Skylon vehicle and its unique Sabre engine mean that we have an inside track on realising our goal,” Bond said.
“Once the tests are complete, Skylon could reduce the cost of getting into space by a factor of ten and improve the reliability by a thousand,” he added.