A small British company with a dream of building a re-usable space plane has won an important endorsement from the European Space Agency (ESA) after completing key tests on its novel engine technology.

Reaction Engines Ltd believes its Sabre engine, which would operate like a jet engine in the atmosphere and a rocket in space, could displace rockets for space access and transform air travel by bringing any destination on Earth to no more than four hours away.

That ambition was given a boost on Wednesday by ESA, which has acted as an independent auditor on the Sabre test program.

“ESA are satisfied that the tests demonstrate the technology required for the Sabre engine

development,” the agency’s head of propulsion engineering Mark Ford told a news conference.

“One of the major obstacles to a re-usable vehicle has been removed,” he said. “The gateway is now open to move beyond the jet age.”

The space plane, dubbed Skylon, only exists on paper. What the company has right now is a remarkable heat exchanger that is able to cool air sucked into the engine at high speed from 1,000 degrees Celsius to minus 150 degrees in one hundredth of a second.

This core piece of technology solves one of the constraints that limit jet engines to a top speed of about 2.5 times the speed of sound, which Reaction Engines believes it could double.

SHROUDED IN SECRECY

With the Sabre engine in jet mode, the air has to be compressed before being injected into the engine’s combustion chambers. Without pre-cooling, the heat generated by compression would make the air hot enough to melt the engine.

The challenge for the engineers was to find a way to cool the air quickly without frost forming on the heat exchanger, which would clog it up and stop it working.

Using a nest of fine pipes that resemble a large wire coil, the engineers have managed to get round this fatal problem that would normally follow from such rapid cooling of the moisture in atmospheric air.