The Douglas A3D Skywarrior was the Navy's first twinjet nuclear bomber. Douglas started designing the airplane in 1947, after the U.S. Navy commissioned studies to determine whether it was possible to overcome weight problems and build a carrier-based strategic bomber. The project was challenging because anything to do with nuclear armament was top secret, and designers had to guess the appearance and weight of the nuclear bombs to be carried aboard. Moreover, the internal bomb bay had to be accessible from the cockpit, so the crew could arm the nuclear device during flight.