British engineers have completed a series of critical tests on the key technology for Sabre, an engine which will enable aircraft to reach the opposite side of the world in under four hours.

The air-breathing rocket engine depends on pre-cooler technology that chills the incoming airstream from over 1,000°C to minus 150°C in less than 1/100th of a second. Now, tests have shown the cooling technology to be frost-free at the crucial low temperature of -150°C.

The European Space Agency (ESA) says it’s satisfied with the tests.

The results mark a major milestone towards the creation of vehicles like Skylon – a new type of reusable space vehicle that will be powered by Sabre engines, designed primarily to transport satellites and cargo into space.

“These successful tests represent a fundamental breakthrough in propulsion technology,” says Alan Bond, who founded Reaction Engines. “Reaction Engines’ lightweight heat exchangers are going to force a radical re-think of the design of the underlying thermodynamic cycles of aerospace engines.”

He says the Sabre engine has the potential to revolutionise life in the 21st century in the way the jet engine did in the 20th.

“Keeping the engine from overheating has been one of the biggest obstacles to developing the SABRE engine, a technology which would enable flying speeds of up to five times the speed of sound, or as much as twenty-five times the speed of sound in Earth’s orbit,” says Philippa Oldham, head of transport and manufacturing at the Institution of Mechanical Engineers.

“This technology also brings us a step closer to flights from London to Sydney that last just a little longer than an on-flight film or even two-week holidays in space.”