Abstract: The invention consists of an engine that converts hydrothermomechanical energy into thrust. There is but a single internal moving part . . . the piston. When in operation, the piston preforms two distinct functions: (1) as a valve allowing intermittent injection of a fuel/air mixture for combustion and (2) as a hydraulic fluid pump. Resultant chemical reactions in the combustion chamber produces intermittent high velocity gases at the exit nozzle of the said engine, which provides sufficient thrust for subsonic and sonic aircraft operations. The intermittent thermal activity and specific manner of braking action of the hydraulic fluid, causes the said piston to function as a hydraulic fluid pump. Thereby providing mechanical energy to power cranes, pumps, compressors, generators, etc., etc., and, or provide impetus for aquatic craft and ground vehicles.