The F-35 has three main models: the conventional takeoff and landing F-35A (CTOL), the short take-off and vertical-landing F-35B (STOVL), and the catapult-assisted take-off but arrested recovery, carrier-based F-35C (CATOBAR). The F-35 descends from the Lockheed Martin X-35, the design that was awarded the Joint Strike Fighter (JSF) program over the competing Boeing X-32.
The F-35 first flew on 15 December 2006. In July 2015, the United States Marines declared its first squadron of F-35B fighters ready for deployment. However, the DOD-based durability testing indicated the service life of early-production F-35B aircraft is well under the expected 8,000 flight hours, and may be as low as 2,100 flight hours. Lot 9 and later aircraft include design changes but service life testing has yet to occur. The U.S. Air Force declared its first squadron of F-35As ready for deployment in August 2016. The U.S. Navy declared its first F-35Cs ready in February 2019. In 2018, the F-35 made its combat debut with the Israeli Air Force.
The U.S. stated plan is to buy 2,663 F-35s, which will provide the bulk of the crewed tactical airpower of the U.S. Air Force, Navy, and Marine Corps in coming decades. Deliveries of the F-35 for the U.S. military are scheduled until 2037 with a projected service life up to 2070.