The "resojet," made by Reaction Motors, Incorporated (RMI) in 1944 to attempt to duplicate the pulsejet engine of the German V-1 cruise missile, was not a rocket, but an air-breathing, reaction-propulsion motor. The project began in July 1944 when RMI engineers were summoned by the Navy Bureau of Aeronautics in Washington, D.C. for consultations on the V-1. The Navy was primarily interested in a potential motor for its own ship-borne missile. The RMI engineers were provided with very sketchy details and were asked to construct and test a duplicate. Work on this development started in mid-July and was completed in early August. Tests were undertaken until September. RMI succeeded in improving the device, but the U.S. armed forces chose to copy the V-1 pulsejet along with the missile, so the resojet was abandoned.

Thiokol Chemical Corporation, which acquired RMI in 1958, gave this motor to the Smithsonian in 1975.