A million Euros of funding (around $1.25 million U.S.) has just been awarded to Reaction Engines Ltd. to develop a radical kind of space launcher known as the Skylon. Far from being a pencils-slim structure rocketing into the sky on a powerful, but expensive and dangerous plume of rocket exhaust, the Skylon is more like a plane, with wings and air-breathing engines.
They key to the design is a technology dubbed Sabre, a hybrid engine of a different kidney. In “aircraft mode” it inhales air like a normal jet engine, but the air is super-cooled by a heat-exchanger and then burned in a rocket engine with hydrogen fuel. When the Skylon reaches the vacuum of space, the air intakes are closed off, and the engine reconfigures itself to burn stored liquid oxygen and hydrogen like a conventional liquid-fueled rocket.
That means the vehicle doesn’t have to carry as much fuel stores to reach orbit. The huge external tank of the Space Shuttle system, by comparison, doesn’t contain enough fuel to reach orbit, hence the solid rocket boosters that make the familiar Shuttle launch shape. And that’s where the Skylon makes its savings–with less fuel to haul into space, the vehicle is simpler and cheaper to build and run. There is no need for expensive launch and recovery facilities, like those needed for the Shuttle, for example.
The aim of the project is to divide the typical cost per kilo of launching a payload by ten. And that would revolutionize the satellite launching business as well as space travel. Sooner than you might think too–the team is confident that it could have a working system capable of carrying twelve ton payloads into orbit within the next decade.
But Skylon isn’t a wholly new idea. In fact it’s extremely close to a previous British space project dubbed Hotol from the 1980s. Hotol was an aircraft-like space launcher that took off and landed on normal runways, and relied on a revolutionary rocket engine that breathed air for thrust. The engine was the Rolls Royce RB545 and it received serious design, planning, and testing attention from RR as well as British Aerospace. Due to financial, technical and patent issues (compounded by the government classifying the RB545), Hotol was canceled in 1988. But several team members went on to form Reaction Engines Ltd., the company behind Skylon.
A few decades of technical advances in materials science and engine design later, the team–and the European funding body, the European Space Agency–thinks the air-breathing rocket design is ready for another go.