Designed as a land-based aircraft, the Neptune never made a carrier landing, but a small number were converted and deployed as carrier-launched using JATO assist , stop-gap nuclear bombers that would have to land on shore or ditch. The type was successful in export, and saw service with several armed forces.
Development of a new land-based patrol bomber began early in World War II, with design work starting at Lockheed's Vega subsidiary as a private venture on 6 December On 19 February , the U. Navy signed a letter of intent for two prototype XP2Vs, which was confirmed by a formal contract on 4 April with a further 15 aircraft being ordered 10 days later. The first aircraft flew in May Production began in , and the aircraft was accepted into service in Potential use as a bomber led to successful launches from aircraft carriers.
Beginning with the P2V-5F model, the Neptune became one of the first operational aircraft fitted with both piston and jet engines. To save weight and complexity of two separate fuel systems, the Westinghouse J34 jet engines on P2Vs burned the β Avgas fuel of the piston engines, instead of jet fuel. The jet pods were fitted with intake doors that remained closed when the Js were not running. This prevented windmilling, allowing for economical piston-engine-only long-endurance search and patrol operations.
Normal crew access was via a ladder on the aft bulkhead of the nosewheel well to a hatch on the left side of the wheel well, then forward to the observer nose, or up through another hatch to the main deck.
There was also a hatch in the floor of the aft fuselage, near the sonobuoy chutes. Before the P-3 Orion arrived in the mids, the Neptune was the primary U. Several features aided the P-2 in its hunter role:. In the short term, carrier-based aircraft were the best solution. The large Fat Man nuclear munitions at that time were bulky and required a very large aircraft to carry them.
