The F-35 Lightning II is still in the development phase, even as it's being delivered to the field and readied for combat operations. As engineers, operators and maintainers discover issues with the aircraft, corrections and fixes are made to current and future aircraft. Concurrent testing and production of all models of the F-35 are per the plan laid out from the beginning of the program. The intent of concurrency is to get weapon systems to the warfighter as quickly as possible and strengthen manufacturing and supply chains. (Photo courtesy of Lockheed Martin)