Abstract: A pulsed detonation engine having an initiator tube fueled with an enhanced fuel mixture is configured in fluid communication with a detonation chamber via a divergent inflow transition section. The divergent inflow transition section has a diverging contoured shape having a rate of divergence continuously dependent upon the diameter of the tube, the critical diameter of the enhanced fuel mixture within the tube and the cross-sectional area of the detonation chamber. The inflow transition section, which may have a stair-step configuration, includes a plurality of fuel and/or air ports to permit the fuel and air to be injected through the transition section and into the detonation chamber. The pulsed detonation engine includes a volume of ejector/bypass air surrounding the detonation chamber, which captures the detonation engine exhaust and mixes the exhaust with the ejector air, and a back pressure device for feeding dynamic pressure ejector air to the interior of the detonation chamber near its outlet end.