Abstract: A combination engine for a flying craft capable of flying at speeds within a wide range from subsonic speeds to hypersonic speeds, is equipped with a rocket engine section that is independent of an atmospheric air supply, and a turbo air jet engine section having a compressor which is driven by a turbine that is also independent of an external air supply. The combination may further include extra fuel supply nozzles for operation as a ram jet which uses the same flow channel as the turbo air jet engine section. A gas generator equipped with two valving mechanisms is arranged coaxially with the rocket engine section. The valving mechanisms are controllable to open the gas generator chamber to the rocket combustion chamber while closing off gas flow to the turbo air jet section or vice versa. Either section can work alone or in parallel and simultaneously with the other section.