A type of jet engine with no moving mechanical compressor or turbine blades. It relies entirely on the high-speed forward motion of the aircraft to ram air into the inlet, compressing it before fuel is injected and ignited. Because it needs preexisting speed to function, a ramjet cannot start from a standstill and requires another propulsion method to reach operating velocity. Combustion occurs at subsonic airflows.
Heard on the job
The missile uses a solid booster to get off the rail before the ramjet takes over for the cruise phase.