The cooler is part of a new type of spaceplane engine demonstrated bye Reaction Engines Ltd (REL), Oxfordshire. The company ran a series of tests on key elements of its Sabre propulsion system under the independent eye of the European Space Agency (Esa).
REL’s idea is for an 84m-long vehicle called Skylon that would do the job of a big rocket but operate like an airliner, taking off and landing at a conventional runway. The vehicle would burn a mixture of hydrogen and oxygen but in the low atmosphere the oxygen would be taken from the air, in the same way that a jet engine breathes air.
Taking its oxygen from the air in the initial flight phase would mean Skylon could fly lighter from the outset with a higher thrust-to-weight ratio, enabling it to make a single leap to orbit, rather than using and dumping propellant stages on the ascent – as is the case with current expendable rockets. A key element is the engine’s ability to manage the hot air entering its intakes at a high speed. These gases have to be cooled prior to being compressed and burnt with the onboard hydrogen.
REL’s solution is a module containing arrays of extremely fine piping that can extract the heat and plunge the inrushing air to about -140C in just 1/100th of a second. Ordinarily, the moisture in the air would be expected to freeze out rapidly, covering the piping in a blanket of frost and dislocating their operation.
It is the innovative helium cooling loop with its pre-cooler heat-exchanger that REL has been validating on an experimental rig.