Outer Space / Technology
Abbreviation of supersonic combustion ramjet engine. A type of air-breathing engine that obtains propulsion by taking in air at supersonic speeds, then compressing it and mixing it (utilizing ram pressure) with fuel at several points throughout the engine. The controlled expansion of this mixture produces net thrust, with an optimum flying speed of between Mach 10 and Mach 25. Can be found in almost all hypersonic and exoatmospheric aircraft as well as spaceplanes. Called the scramjet engine because it works through the supersonic intake of air and its combustion with fuel, usually hydrogen, via ram pressure. Also known as a scram engine. Differs from a ramjet engine in that it keeps the air moving at supersonic speeds, whereas a ramjet engine slows the supersonic airflow to subsonic speeds.