Abstract: A self starting, quick start-up rotary steam/internal combustion engine and a rotary hydraulic motor, with a positive displacement, powered through 360.degree. of each revolution and comprising: a flattened cylindrical flywheel with two diametrically opposed, retractable, hinged power vanes that move through a 90.degree. rotation; a drive shaft connected to the flywheel; an engine housing covering the flywheel, power chamber, exhaust chamber and transition chamber; a "combination backstop for the power chamber and lifter/release for the power vanes"; and means for a continuous internal generation of steam, means for a continuous internal combustion and means for introducing pressurized hydraulic fluid into the power chamber.