The Lockheed–Boeing–General Dynamics YF-22 is an American single-seat, twin-engine, stealth fighter prototype technology demonstrator designed for the United States Air Force (USAF). The design team, with Lockheed as the prime contractor, was a finalist in the USAF's Advanced Tactical Fighter (ATF) competition, and two prototypes were built for the demonstration and validation phase. The YF-22 team won the contest against the Northrop-led YF-23 team for full-scale development, and the design was developed into the Lockheed Martin F-22. The YF-22 has a similar aerodynamic layout and configuration as the F-22, but with notable differences in the overall shaping such as the position and design of the cockpit, tail fins and wings, and in internal structural layout.