The F-15 is a twin engine, high performance, all weather air superiority fighter. First flown in July 1972, the Eagle entered USAF inventory in November 1974. It was the first U.S. fighter to have engine thrust greater than the normal weight of the aircraft, allowing it to accelerate while in a vertical climb. This, combined with low aircraft weight to wing area, makes the Eagle very highly maneuverable. The Eagle was produced in both single-seat and two-seat versions.