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First flown on 17 May 1945, the Neptune was designed as a maritime patrol and anti-submarine warfare aircraft, and this dictated that it have extreme endurance and range, in addition to a large internal weapons bay, defensive capabilities and good short-field capability. Its design featured high-aspect ratio wings, a large fuel load and powerful engines -- a combination which eventually resulted in a production Neptune setting a world distance record of 11,235 miles in 1946, by flying nonstop and unrefueled from Perth, Australia to Columbus, Ohio, USA.
Although the Neptune just missed involvement in WWII, it was used extensively in both the Korean War and the Vietnam War, becoming the standard Anti-Submarine Warfare platform for not only the USA but the Netherlands, Japan and many other nations. In addition to the first production model, the P2V-1, many, many additional variants were produced, serving in such roles as Airborne Early Warning (P2V-3W / P-2D), Nuclear weapons carrier (P2V-3C), VIP transport (P2V-3Z), Special-sensor aircraft (OP-2E/AP-2E), Drone controller (DP-2E / DP-2H), crew trainer (TP-2F), Antarctic skiplane (LP-2J), Electronic surveillance (RB-69A), Target tug (UP-2J) and Gunship (AP-2H).
Today, at least 40 P-2s still serve in civilian roles, mostly as firebombers in the USA. A few are pure warbirds, providing their proud owners with the great range, endurance and utility which defined the Neptune's success while in military service.
The Lockheed P2V Neptune can trace its maritime patrol ancestry back to the Lockheed-Vega Hudson. The Hudson, a twin engined, twin tailed low wing aircraft, was a bomber version of the Model 14 Super Electra airliner. The Hudson was Lockheed’s answer to a British Purchasing Commission search for a general reconnaissance aircraft. Design work began in 1938 and the resulting Model B14L lead to the delivery of more than 2941 Hudsons to the UK and to the USAAF.
Lockheed-Vega’s follow up to the Model 14 was the Model 18 Lodestar. The British, well satisfied with the Hudson, were interested in a 1939 Lockheed-Vega proposal to produce a military version of the Lodestar. After further discussion, the RAF ordered 300 examples of a more advanced development of the Model 18, and christened it Ventura I. As was the case with the Hudson, the USAAF also took delivery of 200 Venturas, designated as the B-34-VE in US service.
When Navy patrol squadrons assumed full responsibility for antisubmarine warfare, the USAAF discontinued procurement of the B-34 so that Lockheed-Vega could concentrate on producing a specially configured maritime patrol version for the Navy. The PV-1 was optimized for its primary mission with an increased fuel capacity, modified defensive armament, the installation of an ASD-1 search radar in the nose and could carry eight 5-inch HVAR rockets mounted on the wings. 1600 PV-1s were delivered to the USN with many aircraft diverted to the RAF, RAAF, RCAF, RNZAF, SAAF, and the Fôrça Aérea Brasileira.
When the production of the Ventura was transferred from the USAAF, the Navy and Lockheed-Vega began discussing a major redesign of the aircraft to further tailor it for the maritime patrol role. The Vega Model 15 had an increased wing span, which allowed an increase in fuel capacity and an increased bomb load. With an estimated increase in range and improved field performance, the Navy ordered 500 aircraft designated PV-2 Harpoon. Delivery of the Harpoons began in March 1944. Delivery of the last PV-2D Harpoon occurred in September 1945 bringing production of the Ventura and Harpoon to an end. After the war, the Navy transferred Harpoons to France, Italy, Japan, the Netherlands, Peru and Portugal.
Even before the United States’ entry into World War Two, it had become apparent that the US Navy would need a land-based patrol bomber with greater range and armament, higher level and climbing speeds and slower approach and landing speeds than the Hudson and Ventura. What the Navy needed was an aircraft designed specifically for the primary mission of day and night ASW and anti shipping operations. Although no official requirement was issued, preliminary work on V-135 was begun in September 1941 by chief engineer John B. Wassall and his Vega team.
The initial concept called for an aircraft with a gross weight of 25,000 to 35,000 lb., power operated turrets, tricycle landing gear and the ability to carry two torpedoes, bombs and depth charges internally. The favored powerplants were a pair of eighteen cylinder Wright R-3550s producing 2000 hp. Mac V. F. Short, at the time, Vice President Engineering of the Vega Airplane Company authorized the first internal work order for design studies of a new aircraft on December 6, 1941.
Progress on the new patrol plane was slow as the Navy needed proven aircraft during the critical months following the Japanese attack on Pearl Harbor. Eventually, by early 1943 the Navy switched its procurement attention from acquiring immediately available aircraft, to supporting the development of newer and more capable types. The Navy issued a letter of intent on February 19, 1943, to the Vega Airplane Corporation for two XP2V-1 prototypes based on the V-146 design study. The V-146 was itself a development of the V-135 with a revised tail, a lowered wing and a relocated dorsal turret. Contact NOa(s)-375 was awarded on April 4, 1944 for the construction of the two prototypes, and ten days later, Contact NOa(s)-3297 for fifteen production P2V-1s. During this time, the PV-2 Harpoon still had a higher priority than the XP2V-1 in both engineering staff and floor space allocation. It was not until the summer of 1944 that project engineer R. A. Baily was able to get the project into high gear.
The main development objective of the V-146 was to maximize target detection and increase offensive power against those targets. Through the use of new designs and improved production techniques, Lockheed was able to meet the design’s need for long range, short takeoff and easy maintenance. This design philosophy would a provide easier production and decrease the manufacturing cost of each individual aircraft.
One design feature was the major portion of the fuselage contour was curved in only one direction which permitted the use of uniformed metal skins. Expensive forming was eliminated by producing the center wing and mid fuselage sections, including the bomb bay door area, as a continuous cross section. This allowed multiple use of numerous parts and assemblies. The wing and fuselage intersection was unfilleted, the wing box running continuously through the fuselage. This also allowed the entire bomb bay load to be directly distributed throughout the wings.
The Neptune was also designed to be manufactured into easily accessible sub assemblies, keeping mating and final assembly time to a minimum. With all of these considerations, the Neptune became much more serviceable. A complete engine change could be accomplished in 30 minutes, a propeller in 22 minutes and an outer wing panel in 79 minutes. The attention to production and tooling details ensured that Lockheed would set economic standards that would set a precedent in the aerospace industry.
In the spring of 1945, thirteen months after the initial contract was awarded, the Neptune was ready to fly.
The fifth P2V-1 airframe (BuNo 89086) was modified during construction to serve as prototype for the P2V-2 version. The 2,300 hp R-3350-8As of the P2V-1 were replaced by the 2,800 hp Wright R-3350-24Ws with water injection. Designated XP2V-2, it was first flown on 7 January 1947.
Delivered between June 1947 and August 1948 the production P2V-2s (Models 026-52-02 and 126-52-02) were powered by the same R-3350-24Ws as the XP2V-2, driving three-bladed propellers. The nose gunner position was replaced by six forward-firing 20 mm cannon in a metal-covered nose, of similar shape to that of The Turtle, and provision for carrying sonobuoys was added. The first eight P2V-2s retained the Bell tail turret introduced on the P2V-ls, whereas the next seventy-two P2V-2s had an Emerson tail turret with two 20-mm cannon installed. The first eight P2V-2s were sent to Emerson in St. Louis, MO where they were retrofitted with the new tail turret.
The P2V-5 was the most numerous Neptune variant produced and would serve as the basis for the largest number of sub-type modifications developed of any of the Neptune series.
First flown on 29 December 1950, twenty-three Model 426-42-06s (124865/124887) were built. The new P2V-5 replaced the six cannon solid nose cone of the P2V-4 with an Emerson Aero 9B turret armed with a pair of 20mm cannon. The 20mm tail turret as well as the .50 caliber machine gun armed dorsal turret remained unchanged from the P2V-4. The P2V-5 was capable of carrying an 8,0001b load of mines, torpedoes, bombs or depth charges and sixteen rockets on under-wing launch stubs, later reduced to 8 with the addition of the J-34s. An APS-20 radar was mounted in the underbelly position just behind the nose wheel doors. The wing tip fuel tanks were enlarged and were moved from an under wing tip position on the P2V-4, to the outside center of the wing tips and could carry an additional 350 gallons of fuel in each tank. In an emergency, the new tip tanks could be jettisoned. In addition, the forward portion of the starboard wingtip tank housed a powerful searchlight with a moveable reflector and arc element that was linked by servomotors to the nose turret guns. The port wingtip tank had APS-8 search radar mounted in its forward portion. The increase in ASW/ECM equipment increased the aircrew to nine men. The Wright Cyclone R-3350-30W engines remained unchanged from the P2V-4. The weight of the additional equipment without an increase in power caused the top speed to drop to 341 mph. However, the added fuel capacity increased the P2V-5's range to 4,750 miles.
They were followed by 147 Model 426-42-11s for the US Navy, the RAF and the RAAF, in which accommodation was provided for an ECM operator, to increase crew size from eight to nine. 98 model 426-42-13s were built for the US Navy (127781/127782 and 128327/128422), and were fitted during production with a 17-ft (5'18-m) tail 'stinger' extension housing a MAD (magnetic anomaly detection) system. 80 Model 426-42-15s (131400/131479) had the MAD 'stinger' extension, an observation nose, and the defensive armament reduced to two 0-50-in guns in the dorsal turret. The Marineluchtvaartdienst (MLD, Royal Netherlands Naval Air Service) received twelve Model 426-42-16s which were similar to the 426-42-13s (with MAD 'stinger', nose and dorsal turrets) but had revised crew accommodation. Finally sixty-four Model 426-45-15s (131480/131543) which differed from the 426-42-15s in being powered by 3,500 hp R-3350-32W Turbo-Compounds were delivered to the US Navy the last of which was delivered in September 1954.
In addition to the US Navy, the P2V-5 would serve the military needs of Argentina, Australia, Brazil, Great Britain, The Netherlands and Portugal.
The Lockheed Model 726, the P2V-7, was the final Neptune variant off the Lockheed production line. First flown on April 26, 1954, Model 726-45-14 was powered by a pair of 3,700hp (with water injection) Wright R-3350-32W Turbo Compound engines and a pair of Westinghouse J-34-WE-36 turbo jet engines. This model had a top dash speed of 364mph making it the fastest of the Lockheed produced Neptunes. The APS-20 search radar with its larger radome was mounted further forward than that on the earlier P2V-5s. The P2V-7 could carry an ordnance load of 10,000 lbs. in a larger weapons bay. The flight deck was raised and a redesigned canopy provided improved visibility. The smaller wing tip tanks of the later P2V-5s were also fitted. An aircrew of nine was carried.
Some early production P2V-7s were equipped with the Aero 9B nose turret and tail turret. These aircraft were later modified with the observer nose and MAD tail. Towards the end of the production run, the dorsal turret was replaced with a skylight observation window.
A total of 287* Neptunes, including forty-eight assembled in Japan by Kawasaki at Gifu, were built under the P2V-7 designation as Model 726-45-14s (148 aircraft for the US Navy, Aéronavale and Japan.) Model 726-45-17s (114 aircraft, with revised accommodation, for the same customers and the RAAF), Model 826-45-14 (25 aircraft for the RCAF, delivered without the under-wing J-34s). The P2V-7B (Model 726-45-18) designation was given to 15 aircraft built for the MLD. Neptune production ended in 1962.
By the 1970s, P-2s had been phased out from all Fleet Patrol Squadrons remaining in service with only twelve Reserve Patrol Squadrons. In April 1978, VP-94 transitioned to the P-3 Orion ending 31 years of P2V Neptune operations with the US Navy.
P2V-7 Neptunes served with the military forces of Argentina, Australia, Canada, France, Japan and The Netherlands.
*This total does not include the 4 P2V-7LP/LP-2J and 5 RB-69As
Specifications:
Manufacturer: Lockheed
Roles: Maritime and antisubmarine patrol
Engines: Two 3,500-hp Wright R-3350-32 turbo-compound radial piston engines, plus two 3,400-lb thrust Westinghouse J34-WE-36 auxiliary turbojets.
Number Built: 1,181.
Number Still Airworthy: ~40.
Nicknames: Owashi ("Giant Eagle") (Japanese Maritime Self-Defense Force designation); Firestar (SP-2H firebomber developed by Aero Union, Chico, California.)
Dimensions:
Weight: Empty 49,935 lbs., Max Takeoff 79,895 lbs.
Wing Span: 103ft. 10in.
Length: 91ft. 8in.
Height: 29ft. 4in.
Performance :
Maximum Speed: 403 mph at 14,000 ft.
Ceiling: 22,000 ft.
Range: 3,685 miles
Armaments:
Two 12.7-mm (0.5-inch) machine guns in dorsal turret,
plus rack for underwing rockets, and
up to 8,000 lbs of bombs, depth charges or torpedoes.
In the Beginning...
Perhaps the most famous Neptune, the "Turtle" was the 3rd P2V-1 off the assembly line modified
for a long distance flight, setting a record that still stands today!
P2V-2, BuAer 39318 of VP-2.
P2V-3C, NAS Alameda, 01/29/52
P2V-4, NAS Los Alamitos, 08/62.
P2V-5/P-2E
P2V-6, Buaer 126529 of NAS Olathe in storage at NAS Alameda, 08/20/60.
P2V-7/P-2H
Later use as a wildfire "Water drop" aircraft
All information and photos Copyright of P2V Neptune.Org and War Bird Alley
