Abstract: A composite gas turbine engine including a fan, a lift device, a compressor, and a turbine for operating the fan, lift device, and compressor. An inner annular duct leads air from the fan to the compressor and turbine, and an outer annular duct leads air from the fan so that it bypasses the compressor and turbine. A supercharger is located between the fan and compressor and within the inner duct. A drive shaft rotated by the turbine is alternatively coupled either to the fan or to the supercharger and lift device. The supercharger raises air pressure flowing to the compressor to a greater degree than does the fan. The drive shaft is connected to a fan shaft and a supercharger shaft through a gearset, and brakes are provided for arresting the motion of the latter two shafts. A third duct leads from the fan to the inner duct while bypassing the supercharger, and means are provided for optionally guiding air into the third duct when the fan is operating, or to the supercharger when the fan is immobilized.