Reaction Engines

Reaction Engines (United Kingdom, founded 1989) is developing the Synergetic Air-Breathing Rocket Engine (SABRE), a hybrid jet/rocket engine that can power aircraft from a runway and then transition to rocket mode for spaceflight. SABRE’s key innovation is a precooler that chills incoming air from over 1,000 °C to −150 °C in 0.01 seconds, preventing engine overheating at high speeds. This enables airbreathing operation up to Mach 5.4 in atmosphere, greatly increasing efficiency before switching to onboard oxygen for the rocket phase to reach orbital velocity. Reaction Engines has successfully tested the precooler technology (cooling air at Mach 3.3 conditions) and is working with partners like BAE Systems and Rolls-Royce to mature the engine. If realized, SABRE could enable reusable spaceplanes that dramatically lower the cost of accessing space.