Patent ID: 6508055
Filing Date: 2003-01-21
Classification: B64C,F02K

Abstract:
A variable bypass jet engine fitted with thrust vectoring exhaust nozzles, wherein supersonic performance is achieved entirely with the use of supercharging and ram effect, no afterburner or thrust augmentation of any kind is employed comprising:a complete low bypass turbofan including a secondary fan unit and an engine core comprising a compressor, combustion chamber, turbines and secondary bypass duct; said turbofan is mounted in the rear of the airframe behind the aircraft center of gravity; a larger diameter main fan unit drivingly connected to said turbofan via a long drive shaft or shafts; said main fan is 2.5 to 3.5 times greater in frontal area than said secondary fan; said main fan is mounted in the forward part of the airframe ahead of the aircraft center of gravity; a long central duct of the same area as said secondary fan; said central duct feeds said secondary fan from the center portion of said main fan; said central duct is located in the center of the airframe and located around the aircraft center of gravity; an annular plenum chamber mounted directly to the rear of said main fan, featuring a split exhaust system ejecting from either side of said main fan; said chamber excludes the portion of airflowm directed into said central duct; said chamber provides main bypass; two forward mounted thrust vectoring exhaust nozzles, one immediately attached to each side of said chamber, arranged to exhaust either rearwards or downwards; two variable area outer ducts, each defined on the inside by a fixed wall, and on the outside by hinged inner and outer doors; said outer ducts are fitted one each side of said central duct and rejoin said central duct downstream behind the aircraft center of gravity; a second plenum chamber, formed at the junction between said central duct and said outer ducts, just ahead of said secondary fan; said outer ducts are fitted directly behind said nozzles; said nozzles feed said outer ducts; each said outer doors are first hinged at the rear, the forward part of each said inner doors are fitted to the forward part of each said outer doors using a second shared hinge, a third hinge is fitted to each said inner doors, about three-quarters towards the rear, hence dividing said inner doors each into two unequal parts; said inner doors are always parallel to said walls with said outer doors in any position, hence said outer ducts have variable area constant along whole length of said walls; said inner and outer door pairings are each fitted with one thrust splitting device mounted on said shared hinge, directly behind said nozzles; said devices are arranged to move transversely across the face of said nozzles, moving in unison with said outer doors, hence varying the degree of supercharging and bypass of the said secondary fan and core; said devices, in conjunction with said doors, provide a smooth and aerodynamic airflow with said doors in any position; said inner doors form a ram into said second chamber when said doors are opened; said doors totally shut off said main bypass when fully open, providing fully supercharged low bypass turbofan mode at subsonic speeds, and providing ramjet mode at supersonic speeds; said main fan freewheels at supersonic speeds, allowing the airflow to pass straight through into said ram; said ram provides said secondary fan with a subsonic airflow at all speeds; said doors totally shut off the supercharging when filly closed, providing high bypass turbofan engine mode; a two-stage combustion chamber, to provide extra fuel in said supercharged mode, fitted within said engine core; a rear mounted thrust vectoring variable area nozzle, with the fixed end fitted to the rear of said secondary bypass duct and arranged to vector the thrust rearwards or downwards; said rear nozzle is of a smaller diameter than said secondary bypass duct when fully closed; said nozzles are only deflected downwards with said doors fully closed.