Since 1989 the UK's Reaction Engines Ltd has been developing technologies to create an air-breathing rocket engine called SABRE. Air-breathing rocket engines will allow spacecraft to reach more than five times the speed of sound, easily allowing them to break orbit without the need of breakaway rockets. And like SpaceX, Reaction Engines is making their experimental rocket possible thanks to advanced metal 3D printing technology.
The SABRE engine is the key to powering Reaction Engines' single stage to orbit Skylon spaceplane, which will be capable of launching itself into Earth orbit from a conventional airport runway. The Skylon's SABRE engines will use oxygen pulled in from the atmosphere to propel the plane up to speeds of mach 5.4 (over 6,000 kph), where it will then switch to its reservoir of hydrogen fuel and onboard liquid oxygen. But in order for an engine to work under those atmospheric conditions, it needs to be able to cool the air stream into the engine from temperatures well over 1,000°C down to minus 150°C in less than 1/100th of a second. And it has to do that while adding only a minimal amount of additional weight to the spaceplane.
