Rolls-Royce LiftSystem

The Rolls-Royce LiftSystem, together with the F135 engine, is an aircraft propulsion system designed for use in the STOVL variant of the F-35 Lightning II. The complete system, known as the Integrated Lift Fan Propulsion System (ILFPS), was awarded the Collier Trophy in 2001.

The F-35B STOVL variant of the Joint Strike Fighter (JSF) aircraft was intended to replace the McDonnell Douglas AV-8B Harrier II and the McDonnell Douglas F/A-18 Hornet used by the United States Marine Corps. It would also replace the British Aerospace Harrier II and the British Aerospace Sea Harrier used by Royal Air Force and Royal Navy. The aircraft had to have a supersonic capability, and a suitable vertical lift system that would not compromise this capability was needed for the STOVL variant. This requirement was met by the Rolls-Royce LiftSystem, developed through a $1.3 billion System Development and Demonstration (SDD) contract from Pratt & Whitney. This requirement was met on 20 July 2001.

Instead of using separate lift engines, like the Yakovlev Yak-38, or rotating nozzles for engine bypass air, like the Harrier, the "LiftSystem" has a shaft-driven LiftFan, designed by Lockheed Martin and developed by Rolls-Royce, and a thrust vectoring nozzle for the engine exhaust that provides lift and can also withstand afterburning temperatures in conventional flight to achieve supersonic speeds. The lifting/propulsion system with its Three Bearing Swivel Duct Nozzle (3BSD) most closely resembles plans for the Convair Model 200 Sea Control Fighter of 1973 than the preceding generation of STOVL designs to which the Harrier belongs.

The team responsible for developing the propulsion system included Lockheed Martin, Northrop Grumman, BAE Systems, Pratt & Whitney and Rolls-Royce, under the leadership of the United States Department of Defense Joint Strike Fighter Program Office. Paul Bevilaqua, Chief Engineer of Lockheed Martin Advanced Development Projects (Skunk Works), invented the lift fan propulsion system. The concept of a shaft-driven lift-fan dates back to the mid-1950s. The lift fan was demonstrated by the Allison Engine Company in 1995–97.

The U.S. Department of Defense (DOD) awarded General Electric and Rolls-Royce a $2.1 billion contract to jointly develop the F136 engine as an alternative to the F135. The LiftSystem was designed to be used with either engine. Following termination of government funding GE and Rolls-Royce terminated further development of the engine in 2011.

Rolls-Royce managed the overall development and integration program in Bristol, UK, and was also responsible for the LiftFan turbomachinery, 3BSM and Roll Post designs. Rolls-Royce in Indianapolis provided the gearbox, clutch, driveshaft and nozzle and conducted the build and verification testing of the LiftFan.

The Rolls-Royce LiftSystem comprises four major components:

The three-bearing swivel module (3BSM) is a thrust vectoring nozzle at the rear of the aircraft which directs engine exhaust to pass either straight through with reheat capability for forward flight, or to be deflected downward to provide lift.