For nearly a year after Nazi Germany unleashed its V-1 flying bomb in June 1944, the early, crude cruise missile plagued English and Belgian cities and countrysides with its terrifying buzzing sound before raining down random death and destruction. Engineers are now refining the pulse jet, the simple but noisy and fuel-wasting power plant that propelled the buzz bomb, into a lightweight and powerful engine that relies on repeated shock wave–driven combustion cycles to produce thrust efficiently. In a decade or two, such pulse detonation engines could power many types of aircraft.