The Joint Strike fighter (JSF) is a program designed to develop a family of stealthy, next- generation replacement strike fighter aircraft for the USAF, USN, USMC and the UK Royal navy and Royal Air Force. The Joint Advanced Strike Technology program ended its research phase in December 1994.

  The Lockheed Martin JSF team includes Northrop Grumman, BAe Systems, Pratt and Whitney and Rolls-Royce. Final assembly of the aircraft will take place at Lockheed Martin’s Fort Worth plant in Texas.

The JSF program entered the Concept Demonstration Phase in November 1996, when two contractors, Boeing (X-32) and Lockheed Martin (X-35), were selected to build and fly Concept- Demonstration aircraft.

The first flight of the X-35A was at 24 October 2000 with LMTAS test pilot Tom Morgenfeld. The X-35A test-program ended November 22, 2000 after 27 test-flights and is rebuild as the X-35B. 

The X-35B Short-take-off/vertical-landing (STOVL) variant, with its unique shaft-driven lift-fan propulsion system, achieved its first vertical take-off and vertical landing on June 23, 2001.

The X-35C first flight February 12, 2001 is the carrier variant, completed 250 practice carrier landings at Naval Air Station Patuxent River, MD. This is the Navy version of the JSF will be similar to the Air Force version except with a stronger internal structure, landing gear, bigger wing, and arresting hook to allow carrier landings.  

The US Department of Defense announced on October 26, 2001, Lockheed Martin as the winner of the JSF program.

During System Development and Demonstration (SDD) phase of the JSF program, the 22 JSF test aircraft (14 of which will have full-flight capability) will undergo an extensive series of ground and flight tests for the Pentagon to establish their compliance with contract specifications. The official production order is expected to be issued to Lockheed Martin in 2006. Both SDD contract performance and partner-country order quantities are factors contributing to future teammate production-order decisions. Approximately 4,500 aircraft are expected to be built.
 

  The first CTOL F-35A has begun airframe assembly at July 12, 2004 and the first wing assembly at August 23, 2004, and is scheduled for its first flight in August 2006. The STOVL F-35B first flight is set for 2007. The F-35A fighter is expected to enter service in 2008, the F-35B in 2012.

Early production lots of all three variants will be powered by the Pratt and Whitney afterburning turbofan F-135 engine, a derivative of the F119 fitted on the F-22. Following production aircraft will be powered by either the F135 or the F-136 turbofan being developed by General Electric and Rolls-Royce.