The Lockheed P-2 Neptune was a maritime patrol and anti-submarine warfare (ASW) aircraft.
Designed as a land-based aircraft, the Neptune never made a carrier landing, but a small number were converted and deployed as carrier-launched, 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 1941.
At first, the new design was considered a low priority compared to other aircraft in development at the time, with Vega also developing and producing the PV-2 Harpoon patrol bomber.
On 19 February 1943, the U.S. Navy signed a letter of intent for two prototype XP2Vs, which was confirmed by a formal contract on 4 April 1944 with a further 15 aircraft being ordered 10 days later.
It was not until 1944 that the program went into full swing.
A major factor in the design was ease of manufacture and maintenance, and this may have been a major factor in the type’s long life and worldwide success.
The first aircraft flew in May 1945.
Production began in 1946, and the aircraft was accepted into service in 1947.
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.
The Convair B-36, several Boeing C-97 Stratofreighter, Fairchild C-123 Provider, and Avro Shackleton aircraft were also so equipped.
To save weight and complexity of two separate fuel systems, the Westinghouse J34 jet engines on P2Vs burned the 115–145 Avgas fuel of the piston engines, instead of jet fuel.
The jet pods were fitted with intake doors that remained closed when the J-34s were not running.
This prevented windmilling, allowing for economical piston-engine-only long-endurance search and patrol operations.
In normal US Navy operations, the jet engines were run at full power (97%) to assure take-off, then shut down upon reaching a safe altitude.
The jets were also started and kept running at flight idle during low-altitude (500-foot (150 m) during the day and 1,000-foot (300 m) at night) anti-submarine and/or anti-shipping operations as a safety measure should one of the radials develop problems.
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.
US Army AP-2E also designated RP-2E used in SIGINT/ELINT operations in Vietnam.
Lockheed produced seven main variants of the P2V.
In addition, Kawasaki built the turboprop-powered P-2J in Japan.
Prototype, two built.
Powered by two 2,300 horsepower (1,700 kW) Wright R-3350-8 engines with four-bladed propellers, with armament of two .50 in machine guns in nose, tail and dorsal turrets, and 8,000 pounds (3,600 kg) of stores in an internal bomb bay.
First production model with R-3350-8A engine, Provision for 16 5-inch (127 mm) HVAR or 4 11+3⁄4-inch (300 mm) Tiny Tim rockets underwing; 14 built.
Fifth production P2V-1 modified as a prototype for P2V-2, Powered by water injected R-3350-24W engines.
Second production model, powered by two 2,800 horsepower (2,100 kW) R-3350-24W engines driving three-bladed propellers, Nose turret replaced by “attack” nose fitted with six fixed 20 mm cannon.
P2V-2N “Polar Bear”
Two P2V-2 modified for polar exploration under Project Ski Jump, Armament removed, with ski landing gear and provision for JATO rockets.
This way the modified P2Vs could still land on a regular runway surface.
One P2V-2 modified as a prototype anti-submarine variant with an AN/APS-20 search radar and additional fuel.
Improved patrol bomber with 3,200 horsepower (2,400 kW) R-3350-26W engines with jet stack engine exhausts, 53 built.
Conversions from other P2V-3 models, including P2V-3C and −3W, fitted with the ASB-1 Low Level Radar Bombing System; 16 converted, Redesignated as P-2C in 1962.
Stop-gap carrier based one-way nuclear-armed bomber, not intended to return for a landing on a carrier.
11 P2V-3s and one P2V-2 modified.
Airborne Early Warning variant, AN/APS-20 search radar; 30 built.
VIP combat transport with armoured cabin in rear fuselage with seats for six passengers.
Retained tail turret, two converted from P2V-3s.
Improved anti-submarine aircraft.
Fitted with AN/APS-20 search radar and provision for dropping sono buoys with additional dedicated sonobuoy operator.
52 built in total.
Surviving aircraft redesignated P-2D in 1962.
Fitted with Emerson nose turret with two 20 mm cannon replacing solid nose of earlier versions, while retaining dorsal and tail turrets.
Modification with two 3,250 pounds-force (14.5 kN) J34 jet engines to increase power on take-off, and 3,500 horsepower (2,600 kW) R-3350-32W piston engines.
Redesignated P-2E in 1962.
P2V-5F converted for drone launch missions.
All weaponry deleted, Redesignated DP-2E in 1962.
P2V-5F with additional electronic equipment.
Redesignated EP-2E in 1962.
P2V-5F with Julie/Jezebel ASW gear, featuring AQA-3 long range acoustic search equipment and Julie explosive echo sounding gear.
Redesignated SP-2E in 1962.
Designation applied to P2V-5F with special SIGINT/ELINT equipment used by the US Army’s 1st Radio Research Company at Cam Ranh Bay Air Base.
Single P-2E converted as permanent test aircraft.
Modified for use as part of Operation Igloo White for sensor deployment over South-East Asia with Observation Squadron 67 (VO-67).
Multi-role version with lengthened weapons bay and provision for aerial minelaying and photoreconnaissance.
Redesignated P-2F in 1962.
Anti-shipping version with provision to carry two AUM-N-2 Petrel anti-ship missiles, 16 built.
Later redesignated P2V-6M then MP-2F.
P2V-6 refitted with J34 jet engines, Redesignated P-2G.
Crew trainer conversion with armament deleted wingtip tanks often deleted. Redesignated TP-2F.
Last Neptune variant produced by Lockheed, powered by R-3350-32W and J-34 engines.
Fitted with lower drag wingtip tanks, AN/APS-20 search radar in a revised radome and a bulged cockpit canopy.
15 aircraft with non-glazed nose fitted with four fixed 20 mm cannon for Royal Netherlands Naval Air Service.
Subsequently fitted with glazed nose and modified to SP-2H standard.
Supplemented by four SP-2H from France.
Four aircraft built with wheel/ski landing gear and JATO gear for Antarctic operations, Redesignated LP-2J.
Additional ASW/ECM equipment including Julie/Jezebel gear, Redesignated SP-2H in 1962.
Naval designation of the RB-69A variant.
Specialized night and all-weather ground attack variant fitted with FLIR and Low Light TV systems, tail turret, fuselage mounted grenade launchers and downwards firing mini guns.
P-2H converted for drone launch and control.
Single P-2H modified with UHF telemetry equipment instead of ASW systems.
Test bed conversion of P2V-H.
Five new built and two converted from P2V-7s for CIA covert operations, obtained with USAF help and operated by ROCAF 34th Squadron.
Aerial reconnaissance/ELINT platform, modular sensor packages fitted depended on the mission needs.
British designation of P2V-5; 52 delivered.
RCAF designation of P2V-7(jet pod not initially fitted to 25 P2V-7 aircraft delivered to RCAF, but subsequently retrofitted)
Kawasaki P-2J (P2V-Kai)
Japanese variant produced by Kawasaki for JMSDF with T64 turboprop engines, various other improvements; 82 built.
91 ft 8 in (27.94 m)
103 ft 10 in (31.65 m)
29 ft 4 in (8.94 m)
1,000 sq ft (93 m2)
NACA 2419 mod
49,935 lb (22,650 kg)
Max take-off weight
79,895 lb (36,240 kg)
2 × Wright R-3350-32W Duplex-Cyclone,
18-cylinder air-cooled radial piston engine,
3,700 hp (2,800 kW) each turbo-compound with water injection
2 × Westinghouse J34-WE-34 turbojet engines,
3,400 lbf (15 kN) thrust each pylon mounted
4-bladed constant-speed propellers
363 mph (584 km/h, 315 kn)
207 mph (333 km/h, 180 kn)
2,157 mi (3,471 km, 1,874 nmi)
22,400 ft (6,800 m)
2.75 in (70 mm) FFAR in removable wing-mounted pods
8,000 lb (3,629 kg) including free-fall bombs, depth charges, and torpedoes.