Pressure and density of a gaseous mixture are increased in the process of introducing the gaseous mixture into the combustor of an air-breathing pulse detonation engine employing atmospheric oxygen as an oxidizer. The exit valve 20 able to be opened and closed is provided at the outlet of the combustor 15, an air cooler 12 is provided in the exit of the intake, and density is increased by exchange of heat of the air received at the intake with a coolant in the air cooler 12. Furthermore, by closing the exit valve 20 provided in the outlet of the combustor during the process of loading the gaseous mixture, transition to the detonation process is possible without expansion of the high-pressure high density air obtained by ram-compression at the intake.