The Lockheed Martin X-35B relied upon a unique propulsion system to achieve short-takeoff and vertical landing (STOVL) flight. At the center of the system is a Pratt & Whitney JSF 119-PW-611 turbofan that powered both conventional and STOVL versions of the X-35. Rolls-Royce developed an shaft-driven lift fan attached at the front and a three-bearing swivel-duct nozzle at the rear to generate downward thrust and bleed air reaction control valves called roll control ducts at the sides to provide stability at low speeds.
This integrated system enabled the X-35B to achieve the world's first short takeoff, level supersonic dash, and vertical landing in a single flight on July 20, 2001. The partners in its development, which also included Lockheed Martin, Northrop Grumman, and BAE Systems, received the prestigious Collier Trophy for 2001 from the National Aeronautics Association.