冲压发动机（Ramjet, stovepipe jet, athodyd）是喷气发动机的一种，它利用了发动机的前向运动来压缩空气，而不使用带有可旋转叶片的压缩机。冲压发动机无法在空速为零的时候产生推力，因此无法使飞行器从静止启动。冲压发动机主要是利用高速迎面气流进入发动机后减速使空气增压的航空发动机。通常由进气道（又称扩压器）、燃烧室和喷管组成。航空器飞行时迎面气流在通过进气道的过程中将动能转变为压力能，经压缩后的空气进入燃烧室与燃料混合进行等压燃烧，生成的高温燃气在喷管中膨胀加速后排出，产生推力。

A ramjet, sometimes referred to as a flying stovepipe or an athodyd (an abbreviation of aero thermodynamic duct), is a form of airbreathing jet engine that uses the engine's forward motion to compress incoming air without an axial compressor. Ramjets cannot produce thrust at zero airspeed; they cannot move an aircraft from a standstill. A ramjet-powered vehicle, therefore, requires an assisted take-off like a rocket assist to accelerate it to a speed where it begins to produce thrust. Ramjets work most efficiently at supersonic speeds around Mach 3 (2,284 mph; 3,675 km/h). This type of engine can operate up to speeds of Mach 6 (4,567 mph; 7,350 km/h).