Hypersonic ‘space plane’ promises four-hour London to Sydney flights

Hypersonic passenger jets of the future could whisk Aussies to the London in just four hours, experts say.

The journey usually takes around 19 to 20 hours — but flight times could be slashed by a new jet engine currently in development.

British firm Reaction Engines is working on a new engine that can propel an aircraft to Mach 5.5.

That’s more than five times the speed of sound, resulting in a top speed of around 6437kph.

The SABRE (Synergetic Air Breathing Rocket Engine) says the engines could be operational as early as the 2030s.

“This is not sci-fi. This is not a pipe dream. This is literally in the works,” said Dr Graham Turnock, of the UK Space Agency.

“It has the potential to turn air travel on its head.

“Certainly the way you conceive air travel will completely change in ten years’ time.”

The engine solves a major problem of high-speed air travel: melting.

Typically such fast propulsion would require huge temperatures that would cause the engine parts to melt.

But SABRE uses liquid gases — including helium — which can cool incoming air from 1000C to -150C in one-hundredth of a second.

And it does this without creating any ice blockages.

SABRE will also be powered by hydrogen — an eco-friendly fuel that produces water vapour when it burns.

The goal is to create a space-plane called Skylon that could take off from a spaceport — like the one set to open in Cornwall in 2021.

It would soar in to the sky and then fly in a low Earth orbit before re-entering the atmosphere and landing back on a runway.