The A3D Skywarrior was designed as a bomber for the US Navy that could deliver nuclear strike capability. At 60,000 lb gross weight, the Skywarrior was the largest and heaviest aircraft ever designed for carrier use. It had a high-mounted wing with 36 degrees of sweepback, and a large internal weapons bay that could carry 12,000 lb of conventional or nuclear weapons. The crew of three was grouped in a pressurized cockpit, tail defence being by means of a radar-controlled barbette with two 20mm guns, these being the only guns carried. The first example flew on September 16, 1953, with production deliveries beginning on March 31, 1956.
(source: United States Navy Aircraft since 1911 by Gordon Swanborough and Peter Bowers)