The Allison J102 was a supersonic missile turbojet engine developed by the Allison Engine Company. The J102 was an axial flow turbojet which was first run in March 1991. In 1997 it was being considered for use in a sea-skimming supersonic target for the United States Navy.
The J102 was a reaction engine which produced thrust by the expulsion of a high-speed gas exhaust. It was created by high pressure (10-200 bar) combustion of solid propellants, consisting of fuel and oxidiser components, within a combustion chamber. The fluid exhaust was then passed through a propelling nozzle which typically used the heat energy of the gas to accelerate the exhaust to very high speed, and the reaction to this pushed the engine in the opposite direction.