Nuclear munitions of the era were bulky and required a large aircraft to carry them. The Navy improvised a carrier-based nuclear strike system by modifying the Lockheed P2V Neptune twin-prop ocean patrol aircraft for carrier takeoff using jet assisted takeoff (JATO) rocket boosters, with initial takeoff tests in 1948. The Neptune couldn't land on a carrier, so the crew either had to make their way to a friendly land base after a strike, or ditch in the sea near a US Navy vessel.
This was obviously not a very practical scheme -- the primary motivation behind it was almost certainly political -- but only days after the atomic attacks on Japan in August 1945, the Navy had begun a competition to acquire a carrier-based nuclear bomber aircraft, leading to award of a contract to the North American company in June 1946 for three prototypes of the "NA-146". The initial NA-146 prototype, designated the "XAJ-1 Savage", performed its initial flight on 3 July 1948, with test pilot Bob Chilton at the controls.
There were difficulties with the flight test program, with both the second and third prototypes lost in accidents, but the aircraft proved satisfactory and so the prototypes were followed by 55 production "AJ-1s", with initial deliveries to the Navy in September 1949.
* The AJ-1 was powered by twin Pratt & Whitney (P&W) R2800-44W radial engines providing 1,790 kW (2,400 HP) each, with one mounted on each wing and driving a four-bladed propeller, plus an Allison J33 centrifugal-flow turbojet providing 20.46 kN (2,090 kgp / 4,600 lbf) thrust in the tail. The jet engine intake was on the back of the aircraft between the wings, featuring a door that closed when the jet engine wasn't in use, reducing drag; the exhaust was under the tail. All three engines used the same type of aviation gas fuel. The twin radials were used for cruise, with the jet engine used for takeoffs and combat boost speed. JATO units could also be attached.
derived from an article by Greg Goebel