The McDonnell F3H Demon was a carrier-based jet fighter aircraft developed by the McDonnell Aircraft Corporation for the United States Navy in the 1950s. It was the first jet fighter in the Navy to have an afterburning engine and a radar fire-control system. The Demon was designed as an all-weather interceptor and fighter-bomber, capable of carrying air-to-air missiles, rockets, bombs, and nuclear weapons. The Demon had a swept-wing design with a single tail and a nose-mounted intake. It was powered by a Westinghouse J40 turbojet engine, which proved to be unreliable and underpowered, causing many accidents and limiting the performance of the aircraft. The Demon was later upgraded with a more powerful Allison J71 engine, which improved its speed and range, but not enough to compete with newer fighters. The Demon was eventually replaced by the McDonnell Douglas F-4 Phantom II in the 1960s.
