Vega 156 (Lockheed XP2V-1 Neptune original proposal)
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 designs 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 Final XP2V-1 Neptune has small diferences from V-146. Principal one was repositioning of upper turret. It 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.
Design Data
Areas and dimensions
Wing area 1000 sq.ft
Horizontal tail area 220 sq.ft
Vertical tail area 175 sq.ft
Wing span 100 ft
Length overall 76ft.4in
Height overall - 27ft.10in
Power plants
Take-off power/rpm- 2300/2800
Military power/rpm/alt 1900/2600/15.000
Normal power/rpm/alt 2100/2400/s.l
Propeller gear ratio 4.375
Propeller Hamilton Stand. 4 blades 15 dia
Crew
Nose gunner
Pilot
Co-pilot radar watcher
Navigator radar watcher
Radio operator
Mid-ship turret operator
Tail gunner
Armor
Total weight armor plate 1032 lbs.
Open/close door Shift+E
Estimated performance
At 45.000 lbs.gross with armament and radio antennae in-stalled and with camouflage paint.
Full speed at sea level. Military power/mph 2300/292
Full speed at critical altitude 15.000 ft.nor.pwr/mph 1900/315
Stalling speed at sea level (gross wt 42.000)mph 1900/315
Service ceiling. Normal power 30.000 ft.
Single engine service ceiking. Normal power 15.000 ft.
Maximum endurance at 47.800lbs. hours 25.6
Maximum range at normal operating wt of 47,800 2.200 gal.
with 0 lbs. explosive load 4.150 miles
with 2.760 lbs. Explosive load ( 8 depth bombs) - 3.500 mi.
with 4.310 lbs. Explosive load ( 2 torpedoes) - 3.030 mi.
Takeoff distance in calm (45.000 gross wt) 1.660ft.
Takeoff distance in calm (47.800 gross wt) 1.870ft.
