Lockheed Martin X-35B STOVL

The X-35B is the technology demonstrator for the Joint Strike Fighter, a stealthy, supersonic, multi-role fighter. Three operational F 35 versions are planned. The conventional variant, designed for the U.S. Air Force, will be built in the largest quantities. The U.S. Navy's carrier variant features larger wing and control surfaces, additional wingtip ailerons, and a special structure to absorb the punishment of catapult launches and arrested landings. Originally, the short takeoff/vertical landing variant was to be used by the US Marine Corps, the United Kingdom, and even the USAF in smaller numbers. Budget constraints continue to impact the future of the F-35 and the final production run has not yet been determined. The STOVL version (F-35B) is equipped with a shaft-driven lift-fan propulsion system, which enables the aircraft to take off from a short runway or small aircraft carrier and to land vertically. The F-35, as the production version is designated, was conceived as the replacement for many aging fighters, such as the F-16, A-10, F/A-18 and AV-8B Harrier. Given the rapid development of unmanned aircraft, the F-35 may also be the last piloted fighter produced in large numbers.

The massive lift-fan propulsion system can now be seen on display next to the X-35B at the Steven F. Udvar Hazy Center near Dulles Airport.

The Engine

The Pratt & Whitney JSF 119-PW-611 turbofan deflects thrust downward for short takeoff/vertical landing capability. The Air Force and Navy versions use a thrust-vectoring exhaust nozzle. The Marine Corps and Royal Air Force/Navy version has a swivel-duct nozzle; an engine-driven fan behind the cockpit and air-reaction control valves in the wings to provide stability at low speeds. This unique propulsion system won the prestigious Collier Trophy in 2001.