X-35B

The X-35B was the Short Takeoff and Vertical Landing (STOVL) demonstrator designed to meet the requirements of the U.S. Marine Corps, the British Royal Air Force, and the Royal Navy.

These branches required an aircraft capable of operating from austere bases and smaller amphibious assault ships.
The X-35B was the modified X-35A airframe equipped with a revolutionary propulsion system.
The defining feature of the X-35B was its shaft-driven lift fan system, developed in partnership with Rolls-Royce, situated just behind the cockpit. When combined with a thrust-vectoring rear engine nozzle that could swivel downward, this system allowed the aircraft to hover, land vertically, and take off in very short distances. The X-35B secured Lockheed Martin's victory in the JSF competition by successfully completing a rigorous test flight where the aircraft performed a short takeoff, accelerated to supersonic speeds, and concluded with a vertical landing all in a single sortie.