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SABRE Engine

air-breathing rocket engine South East,

Model of spaceplane.
Model of the 1990s Skylon spaceplane, at its heart were two SABRE engines. Science Museum/ Science and Society Picture Library

Developed by Alan Bond, Richard Varvill and John Scott-Scott of Reaction Engines over the last two decades, the Synergetic Air-Breathing Rocket Engine – SABRE - is a new class of engine that can operate in both air-breathing jet and rocket modes so that it can operate at speeds of up to five times the speed of sound and be used to enter Earth orbit.

The air breathing design aims to reduce the weight of an on-board oxidiser such as liquid oxygen, needed by conventional rocket engines by hundreds of tons. This weight saving would enable the transition from single-use multi-stage launch vehicles to multi-use single stage launch vehicles which suck in atmospheric air as a source of oxygen (as in a typical jet engine) just after launch, then switch to on-board liquid oxygen in space.

In both modes the thrust is generated using the rocket combustion chamber and nozzles.  While this sounds simple, the problem is that in air-breathing mode, the air must be compressed to around 140 atmospheres before injection into the combustion chambers which raises its temperature so high that it would melt any known material. SABRE avoids this with innovative pre-cooler technology designed to cool the incoming airstream from over 1,000°C to minus 150°C in less than 1/100th of a second.  The Air is compressed in a conventional compressor with a very high pressure ratio and forced into a rocket combustion chamber. The same combustion chamber is then used for the rocket part of the ascent to orbit where the oxidiser is now liquid oxygen taken from on board propellant tanks

Science Museum

Engineering, Mathematics,
South East
Reaction Engines, Culham Science Centre near Abingdon, Oxfordshire
Key Individuals
Alan Bond,