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. 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. It is being designed and built by an aerospace industry team led by Lockheed Martin. The F-35 took its first flight on 15 December 2006.
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. The United States Air Force (USAF) budget data in 2010, along with other sources, projects the F-35 to have a flyaway cost from US$89 million to US$200 million over the planned production of F-35s. Cost estimates have risen to $382 billion for 2,443 aircraft, at an average of $156 million each. The rising program cost estimates have cast doubt on the actual number to be produced for the U.S. In January 2011, the F-35B variant was placed on "probation" for two years because of development issues.