The LTV A-7 Corsair II is an American carrier-capable subsonic light attack aircraft designed and manufactured by Ling-Temco-Vought (LTV). The LTV A-7 Corsair II is a carrier-based subsonic light attack aircraft introduced to replace the United States Navy s A-4 Skyhawk, initially entering service during the Vietnam War. The Corsair was adopted by the United States Air Force, as well as the Air National Guard, to replace the A-1 Skyraider, F-100 Super Sabre and F-105 Thunderchief. The aircraft was also exported to Greece in the 1970 s and Portugal and Thailand in the late 1980 s. The A-7 airframe design was based on the successful supersonic F-8 Crusader produced by Chance Vought. It was one of the first combat aircraft to feature a head-up display, an inertial navigation system (INS) and a turbofan engine. A-7A was the first production version. Early USN Corsair IIs had two 20 mm Colt Mk 12 cannons with 250 rounds per gun. Maximum ordnance, carried primarily on the wing pylons, was theoretically 15,000 lb (6,804 kg), but was limited by maximum takeoff weight, so the full weapon load could only be carried with greatly reduced internal fuel; 199 built.