The North American F-100 Super Sabre is an American twin-seat supersonic fighter-bomber designed to replace the North American F-86 Sabre. Powered by a Pratt & Whitney J57 turbojet engine, it is capable of reaching speeds over Mach 1.4. The F-100 is armed with four 20mm M39 Cannon and can carry up to 3,190kg of ordnance. Although a variety of models were put into production, the F-100D is the definitive version; it has improved avionics, aerodynamics and the capability to fire Heat-Seeking missiles such as the AIM-9 Sidewinder. The F-100 played a crucial role in the early stages of the Vietnam War, conducting numerous close air support and strike missions. Its introduction paved the way for subsequent supersonic fighters such as the McDonnell Douglas F-4 Phantom II.