The F-15 Eagle is a twin engine, high performance, all-weather air-superiority fighter. The Eagle entered operational service in 1974 and has been crucial to defending the United States ever since. A modernization program brought about avionics and structural improvements to create the F-15C (shown here) in 1979, followed by the two-seat, dual-role (fighter and bomber) F-15E "Strike Eagle," with increased payload capacity in 1986.