Abstract: To provide a turbofan jet engine for a supersonic aircraft, which enables a supersonic cruise with small additional drag due to engine installation while minimizing the jet noise at takeoff. In the turbofan jet engine, two fans, i.e., a front fan and an aft fan, are disposed, and an air inlet and an air outlet are provided on each of the front and aft fans, whereby at takeoff, air is introduced to each of the air inlets of the front and aft fans to drive the front and aft fans in parallel, and the air is then ejected from each of the outlets. On the other hand, during a supersonic cruise, an inlet of an aft fan duct is coupled to an outlet of a front fan duct, where external air is introduced only to an air inlet of the front fan duct and the air compressed through the front fan is fed to the aft fan duct and further compressed through the aft fan, and ejected from a nozzle, so that the front and aft fans are driven in series.

Abstract: To provide a turbofan jet engine for a supersonic aircraft, which enables a supersonic cruise with small additional drag due to engine installation while minimizing the jet noise at takeoff. In the turbofan jet engine, two fans, i.e., a front fan and an aft fan, are disposed, and an air inlet and an air outlet are provided on each of the front and aft fans, whereby at takeoff, air is introduced to each of the air inlets of the front and aft fans to drive the front and aft fans in parallel, and the air is then ejected from each of the outlets. On the other hand, during a supersonic cruise, an inlet of an aft fan duct is coupled to an outlet of a front fan duct, where external air is introduced only to an air inlet of the front fan duct and the air compressed through the front fan is fed to the aft fan duct and further compressed through the aft fan, and ejected from a nozzle, so that the front and aft fans are driven in series.

Abstract: A jet engine for supersonic aircraft which enables supersonic flight and high fuel efficiency to be achieved while suppressing noise at take-off. The engine comprises a front engine consisting of a turbofan engine, and a rear engine or engines consisting of a turbofan or turbojet engine disposed to the rear of said front engine, the rear engine(s) being coupled switchably by a tube to the bypass duct of the front engine, the air inlet(s) of the rear engine(s) being coupled to the bypass duct during supersonic flight, or during acceleration to supersonic speed, whereby the pressure and temperature of the bypass air from the front engine is raised by the rear engine(s), and the air inlet(s) of the rear engine(s) being separated from the bypass duct during take-off, in such a manner that the bypass air is discharged without the temperature or pressure thereof being raised further.