Lockheed Martin JSF Works to Fan the Competition

With flight testing of its naval and air force versions of the Joint Strike Fighter complete, Lockheed Martin has entered what is expected to be the most challenged phase of its flight test program-validation of its X-35B short-takeoff/vertical landing variant for the U.S. Marines and UK Royal Navy.

Lockheed Martin recently installed the flight-ready, shaft-driven lift fan in the X-35B, with first STOVL flight scheduled for late June or early July, when the aircraft begins a series of vertical takeoffs and landings. Transitions to and from STOVL and conventional flight modes will follow.

The X-35B, with more than 27 hours of flying time on its airframe, has completed all of its conventional flight requirements. The JSF variant is designed to replace the AV-8B Harrier, with more than twice the range on internal fuel, supersonic operation, and internal weapons housing.

The shaft-driven lift fan propulsion system includes a thrust-vectoring nozzle, wing-mounted "roll post" ducts that provide lateral control and additional thrust, and Rolls-Royce counter-rotating fan-mounted immediately aft of the cockpit-driven by the aircraft's F119-611 Pratt & Whitney engine via a drive shaft. The fan's cool thrust multiplies the engine's lifting force and contributes to a more benign ground environment.

Flight testing for both the X-35A conventional takeoff and landing variant for the U.S. Air Force and UK RAF and X-35C naval variant for the U.S. Navy and Royal Navy was completed with the two aircraft meeting all air force and navy requirements.

Flight test objectives met for the X-35C include: total flights (73); total flight hours (58); speed achieved (Mach 1.22); G achieved (4.8); altitude (34,000 feet); angle of attack (20 degrees); and total field carrier landing practices (250).

The X-35C, which completed its flight test program in March, features a larger wing and control surfaces than other JSF variants for carrier landings. One interesting milestone for the X-35C was a 2,500-mile transcontinental flight from Edwards AFB in California to Patuxent River Naval Air Station in Maryland in February, which Lockheed Martin says was the first-ever coast-to-coast flight for an "X" plane.

Flight test objectives met for the X-35A include: total flights (27); total flight hours (27.4); speed achieved (1.05); G achieved (5.0); altitude (34,000 feet); and angle of attack 20 degrees). The X-35A completed its flight-test program last November.

All three Lockheed Martin JSF variants carry weapons in two parallel bays located in front of the main landing gear. The X-35B STOVL variant does not carry an internal gun, though a missionized external gun is optional. For all three fighters, the canopy, radar, ejection system, subsystems and most of the avionics are common.
All three variants are powered by the P&W F119-611, which is derived from the same afterburning turbofan powerplant for the F-22 Raptor.

Besides Pratt, Lockheed Martin's main JSF partners are Northrop Grumman and BAE Systems. Northrop Grumman brings tactical aircraft integration, carrier suitability, stealth technologies, avionics system integration, sensors and advanced manufacturing techniques to the program. BAE provides its expertise and experience in STOVL technology, subcontract management and lean manufacturing.

The JSF supersonic stealth fighter is designed to replace aging fighter aircraft in the U.S. and UK, including the A-10, F-14, F-16, F/A-18 and Harrier.