The Lockheed Martin F-35 Lightning II is a family of single-seat, single-engine, fifth generation multirole fighters under development to perform ground attack, reconnaissance, and air defense missions with stealth capability.[7][8] The F-35 has three main models; one is a conventional takeoff and landing variant, the second is a short take off and vertical-landing variant, and the third is a carrier -based variant.

The F-35 is descended from the X-35, the product of the Joint Strike Fighter (JSF) program. JSF development is being principally funded by the United States, with the United Kingdom and other partner governments providing additional funding.[9] It is being designed and built by an aerospace industry team led by Lockheed Martin.[9] The F-35 took its first flight on 15 December 2006.[1]

The United States intends to buy a total of 2,443 aircraft for an estimated US$323 billion, making it the most expensive defense program ever.[10] The United States Air Force (USAF) budget data in 2010, along with other sources, projects the F-35 to have a flyaway cost that ranges between US$89 million and US$200 million over the planned production of F-35s, depending on the variant.[11][12][13][14] Cost estimates have risen to $382 billion for 2,443 aircraft, at an average of $92 million each.[15] However, rising program cost estimates have cast doubt on the actual number to be produced for the U.S.[15] In January 2011 Defense Secretary Robert Gates expressed the Pentagon's frustration with the skyrocketing costs of the F-35 program when he said "The culture of endless money that has taken hold must be replaced by a culture of restraint."[15] Focusing his attention on the troubled VTOL F-35B Gates ordered "a two-year probation", saying it "should be canceled" if corrections are unsuccessful.[15] Private analysts say the whole F-35 program is becoming a money pit. "The incredibly unfortunate phrase 'too big to fail' applies to this aircraft more than any other defense program", said Richard Aboulafia, an aerospace industry analyst with the Teal Group.[15]
The JSF program was designed to replace the United States military F-16, A-10, F/A-18 (excluding newer E/F "Super Hornet" variants) and AV-8B tactical fighter aircraft. To keep development, production, and operating costs down, a common design was planned in three variants that share 80 percent of their parts:

* F-35A, conventional take off and landing (CTOL) variant.
* F-35B, short-take off and vertical-landing (STOVL) variant.
* F-35C, carrier-based CATOBAR (CV) variant.

Lockheed Martin claims the F-35 is intended to have close and long-range air-to-air capability second only to that of the F-22 Raptor.[7] The F-35 is required to be four times more effective than legacy fighters in air-to-air combat, eight times more effective than legacy fighters in air-to-ground combat, and three times more effective than legacy fighters in reconnaissance and suppression of air defenses – while having better range and requiring less logistics support