A pulse detonation engine (10) is provided with an aerovalve (14) for controlling the pressure of injected propellants (Ox, Fuel) in an open-ended detonation chamber (26). The propellants are injected at such pressure and velocity, and in a direction generally toward a forward thrust wall end (16) of the detonation chamber (26), an aerovalve (14) is formed which effectively inhibits or prevents egress of the propellant from the detonation chamber (26). A shock wave (34) formed by the injected propellant acts, after reflection by the thrust wall end (16) and in combination with the aerovalve (14), to compress and conserve, or increase, the pressure of the injected propellant. Carefully timed ignition (28) effects a detonation pulse under desired conditions of maintained, or increased, pressure. Termination of the propellant injection serves to “open” the aerovalve (14), and exhaust of the combusted propellants occurs to produce thrust. Alternate embodiments of propellant injection mechanisms (12, 112) provide pulse valves (24, 122, 124) each having a fixed slotted disk (40, 140, 240) and a rotating slotted disk (42, 142, 242) to provide the desired high speed valving of discrete pulses of propellant for injection.