Large single-engined attack aircraft. The A-1 (originally designated BT2D, and later AD) Skyraider was designed as a single-seat attack aircraft to replace the less attractive BTD, and was much simpler and lighter. It was too late for WWII, but much used in Korea and later in Vietnam. The Skyraider was a very effective attack aircraft, but exhausting for the pilot. There were also multi-place versions, ECM and AEW aircraft, and ASW versions. Some of the 3180 Skyraiders built were still in combat service in 1979.