A pulse-jet engine produces thrust through intermittent (pulsed) combustion inside a resonant tube with few or no moving parts. Fuel-air ignites, causing a pressure spike that drives hot gases out the exhaust to create thrust; the outflow then induces a brief vacuum, drawing in fresh mixture so the cycle repeats dozens of times per second. With no compressor or turbine, pulse-jets are cheap, lightweight, and high thrust-to-weight, yet they suffer from low efficiency, very high noise, and heavy fuel burn.

History note: The V-1 flying bomb used the Argus As 014 valved pulse-jet—famous for its low cost sheet-metal build and the iconic “buzz bomb” sound.

Main types:

Valved: Inlet reeds close at ignition, forcing flow out the exhaust. Simple, punchy, but reed durability is a constraint.

Valveless: Geometry steers the flow; fewer parts, but precise tube tuning (length/diameter) is critical.

Where it shows up today:

Model aircraft, industrial hot-air/drying systems, and experimental setups.

Don’t confuse it with PDE: A pulse-jet uses deflagration, while a Pulse Detonation Engine targets detonation—offering higher theoretical efficiency.

In one line: A pulse-jet is a pulsed-combustion jet engine—simple, cheap, and powerful, but inefficient and extremely loud.