| PN | |
|---|---|
 Naval Aircraft Factory PN-12 | |
| General information | |
| Type | Patrol flying boat |
| National origin | United States |
| Manufacturer | Naval Aircraft Factory |
| Primary user | United States Navy |
| History | |
| Retired | 1938 (PK-1) |
| Developed from | Felixstowe F5L |
| Variant | Hall PH |
TheNaval Aircraft Factory PN was a series of open cockpit Americanflying boats of the 1920s and 1930s. A development of theFelixstowe F5L flying boat of theWorld War I, variants of the PN were built for theUnited States Navy byDouglas,Keystone andMartin.
The PN flying boats were twin-enginebiplanes with their engines mounted in nacelles between the fabric-covered wings. Other than on the PN-11 which had a different hull form, the hull had large chines running back to the first step similar to those on the F.5L. It had a standard crew of five, but was capable of carrying a relief crew for long patrols.[1] Early machines had wood hulls and wings, with the wings covered in fabric, while various versions replaced these with metal components. A wide variety of V-12 and radial engines were fitted, due to problems with several of the engines chosen, with later versions generally using radial engines.
At the end ofWorld War I theUnited States Navy was operating theCurtiss H.16 and theFelixstowe F5L Long-range patrolflying boats, which had been developed in collaboration with the British. TheF.5L was a license-built version of the BritishFelixstowe F.5 using the AmericanLiberty engine. The series of Felixstowe flying boats, developed by theSeaplane Experimental Station, had started with improving the hull of theCurtiss America.
PN-5 was the new designation assigned to F.5Ls built by theNaval Aircraft Factory after 1922, although identical aircraft built before then retained the F.5L designation. Under the new designation system, P indicated that the role was Patrol, and N denoted aircraft built by the US Navy's Naval Aircraft Factory. Numbers 1-4 were skipped.
ThePN-6 had an enlarged curved fin with an unbalanced rudder. The first two examples had been ordered as the final two F.5Ls, and had been designated as F.6Ls, with the new PN-6 designation coming into effect in 1922.[2] Some F.5L/PN-5s were later upgraded to PN-6 standard. Neither the PN-5 or the PN-6 designation was used outside of official paperwork, and these aircraft were simply referred to as F.5Ls.
ThePN-7 was a 1925 development with an improved thicker section, shorter-span wings with a more modernairfoil section, and were powered by two experimental 525 hp (391 kW)Wright T-2V-12 engines.[3] Two were built.
ThePN-8 was developed due to problems with the wooden hull, which quickly absorbed hundreds of pounds of water and was maintenance intensive, so two aircraft with a metal hull of the same shape as the F.5Ls, and fitted with the new wing, were built. Due to reliability problems with the Wright T-2, they were powered by two 475 hp (354 kW) V-12Packard 1A-2500 engines.[3]
The twoPN-9s were converted from PN-8s, after being fitted with a redesigned broad-chord tail to fix a vibration problem.
FourPN-10s were built, and while similar to the PN-9, each was given a different engine as the Packard 1A-2500 engines were disappointing. One was fitted withPackard 1A-1500 and another with a Packard 3A-1500, both V-12 water-cooled engines and one each was fitted with theWright R-1820 andPratt & Whitney R-1690 radial engines. The wings of the first two Packard powered aircraft had a wood structure, while the second pair with the radial engines had wings with a metal structure, both with a fabric covering.
The fourPN-11s had a new metal hull with a round turtle deck and lacking the previously characteristic enlarged chines and had a new empennage with twin fins and rudders. One aircraft was fitted with twoWright R-1750 radial engines, while one aircraft were fitted with twoPratt & Whitney R-1690 radial engines as theXPN-11, which was later redesignated as theXP4N-1. Two aircraft were fitted withWright R-1820 radial engines and while ordered as anXP4N-1 were designated as theXP4N-2 when they entered service.
The two metal wing radial-engine powered PN-10s were redesignated asPN-12s, which combined the revised wings of the PN-7 but reverted to the metal hull of the PN-8 with the enlarged chines and was fitted with the more reliable radial engines. The fin was further enlarged, with a straight leading edge. It would see extensive production to re-equip the Navy's patrol squadrons.[4]
As the production capacity of the Naval Aircraft Factory was limited, production was contracted out to several aircraft companies, with versions being built byDouglas as thePD-1, byKeystone as thePK-1 and byMartin as thePM-1 andPM-2.[1] These each had their own differences from the PN-12, as the Keystone PK-1 and Martin PM-2 the twin fins and rudders of the PN-11, while the PM-1 and PM-2 also had an enclosed cockpit, and the PK-1 had a modified hull form with a sharper bow.
These also formed the basis for theHall PH flying boats, with a different hull fitted with an enclosed cockpit, and some of these remained in service untilWorld War II.
The early prototypes of PN sea planes were used in a series of long-distance flights. During the afternoon of 31 August 1925, an attempt was made to fly a pair of PN-9 planes non-stop fromSan Francisco toHawaii, a distance of nearly 2,400 miles (3,864 km) — a trip anticipated to take 26 hours to complete.[5] The first plane to start was forced to land 300 miles (480 km) outside of San Francisco due to a failure of oil pressure, with the crew rescued by the destroyerUSSWilliam Jones and the aircraft towed back to port.[5]
The second PN-9 to depart, captained by U.S. Navy Commander John Rodgers, flew 1,841 miles (2,963 km) before running out of fuel when anticipated tailwinds that would have slowed gasoline consumption did not materialize.[5] The plane was unable to make contact with the naval airplane tenderUSSAroostook, a ship stationed along the PN-9's flight path and was forced to land at sea when both engines stopped functioning.[5] With power lost, the plane was unable to send or receive radio signals.[5] Although this was at the time a new distance record forseaplanes, the plane remained hundreds of miles short of the nearest landfall and the situation of the crew, with limited quantities of food and water, appeared dire.
Since seas were moderate, the decision was made to attempt to sail the plane to Hawaii.[5] The crew then rigged crude sails made from fabric torn from the aircraft's wings and sailed the aircraft a further 450 miles (720 km), finally being spotted on the ninth day about 15 miles (24 km) off the southeast coast of the Hawaiian island ofKauai.[5] In the aftermath of the headline-grabbing rescue, Commander Rogers was promoted to the position of Assistant Chief of the Navy's Bureau of Aeronautics.[5] PN-9 No. 1, the same plane sailed to Hawaii, did not fare as well, later ditching in theCaribbean Sea during an attempted long-distance flight toSouth America and subsequently sunk as a navigation hazard.[6]
The two PN-12s were also used to set various records, including range and speed over circuit records.[4]
The various production derivatives of the PN-12 entered service with the US Navy from 30 April 1928, when VP-7D received its first Douglas PD-1, remaining in service until July 1938, when the last Keystone PK-1 was retired.[1]
Three Martin PM-1s were also supplied to theBrazilian Navy in 1930, and used in bombing raids during the1932 revolution.[7]
Data from United States Navy Aircraft since 1911[10]
General characteristics
Performance
Armament
Related development
Aircraft of comparable role, configuration, and era
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