Pulsejet

A pulsejet is a jet engine in which combustion happens in repeated pulses instead of continuously. It can be built with few or no moving parts and can run while standing still, because it does not need forward motion to force air into its inlet. The best known example is the Argus As 109-014 that powered the German V-1 flying bomb. Two main families exist: the traditional valved design, in which one-way valves close when the fuel mixture ignites so that the hot gas leaves only through the tailpipe, and the valveless or acoustic design, which controls the flow by the geometry of its tubes. The cycle repeats dozens or hundreds of times a second, which produces the loud buzzing sound of the V-1. Pulsejets are light, simple and cheap, but they compress the air poorly, so they burn fuel inefficiently and are noisy. Who first built one is a matter of competing claims, including patents by Teleshov in 1867, Karavodin in 1906 and Marconnet in 1908. Uses today include target drones, model aircraft and industrial drying and heating.