An air-breathing pulsed jet engine for aircraft propulsion which employs a piston compressor rather than much more expensive axial or centrifugal compressors and turbines employed by conventional turbojet engines. The engine is similar to the common two-cycle gasoline engine, except its cylinder head comprises a jet nozzle with an internal pressure-activated nozzle-blocking valve. A spring keeps this valve closed during the engine's compression stroke when the piston, connected to a crankshaft and flywheels by a connecting rod, is forced by the moment-of-inertia of the flywheels toward the cylinder head. When ignition and combustion of the compressed air and fuel occurs slightly before the piston reaches the top of its stroke, the much greater pressures within the engine's combustion chamber force the valve to pivot open. This allows a jet of combustion gases to be released through the jet nozzle into the atmosphere. The reactive forces of the gas jet work against the piston to produce linear thrust (due to the moment-of-inertia of the flywheels) and to store up energy in the flywheels to motivate the piston through the next compression stroke. The jet pulse continues until the pressure inside the combustion chamber drops to a predetermined level, when the spring is able to close the valve. Since the pressures inside the combustion chamber of a gasoline engine are on the order of those inside many rocket motors, the thrusts imparted to the engine during each jet pulse is substantial.