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(Source: U.S. Navy)

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In World War II, PBYs were used as anti-submarine warfare aircraft, patrol bombers, convoy escorts, search and rescue aircraft, and transports. The PBY was the most successful aircraft of its kind, as no other flying boat was produced in greater numbers. The last active military PBYs were not retired from service until the 1980s. Even today, over seventy years after its first flight, the aircraft continues to fly as an airtanker in aerial firefighting operations all over the world.

Development

Background

The PBY was originally designed to be a patrol bomber, an aircraft with a long operational range intended to locate and attack enemy transport ships at sea in order to compromise enemy supply lines. With a mind to a potential conflict in the Pacific Ocean, where troops would require resupply over great distances, the U.S. Navy in the 1930s invested millions of dollars in developing long-range flying boats for this purpose. Flying boats had the advantage of not requiring runways to take off and land, in effect having the entire ocean available as its runway. Several different flying boats were adopted by the Navy, but the PBY was the most widely used and produced.

Although slow and ungainly, PBYs distinguished themselves in World War II as exceptionally reliable. Allied armed forces used them successfully in a wide variety of roles that the aircraft was never intended for. They are remembered by many veterans of the war for their role in rescuing downed airmen, in which they saved the lives of thousands of aircrew shot down over the Pacific Ocean.

Prototyping

As American dominance in the Pacific Ocean began to face competition from Japan in the 1930s, the U.S. Navy contracted Consolidated Aircraft and Douglas Aircraft Corporation in October 1933 to build competing prototypes for a patrol flying boat. Naval doctrine of the 1930s and 1940s used flying boats in a wide variety of roles that today are handled by multiple special-purpose aircraft. The US Navy had adopted the Consolidated P2Y and Martin P3M models for this role in 1931, but both aircraft proved to be underpowered and hampered by short ranges and low maximum payloads.

Consolidated and Douglas both delivered single prototypes of their designs, the XP3Y-1 and XP3D-1, respectively. PB stood for Patrol Bomber, with Y being Consolidated Aircraft’s manufacturer identification. Consolidated's XP3Y-1 was an evolution of the XPY-1 design that had originally competed unsuccessfully for the P3M contract two years earlier and of the XP2Y design that the Navy had authorized for a limited production run. Although the Douglas aircraft was a good design, the Navy opted for Consolidated's prototype because the projected cost was only $90,000 per plane.

Consolidated's XP3Y-1 design (company Model 28) was revolutionary in many ways. The aircraft had a parasol wing with internal bracing that allowed the wing to be a virtual cantilever, except for two small streamlined struts on each side. Stabilizing floats, retractable to form streamlined wingtips in flight, were another aerodynamic innovation. The two-step hull design was similar to that of the P2Y, but the Model 28 had a cantilever cruciform tail unit instead of a strut-braced twin tail. Cleaner aerodynamics gave the Model 28 improved performance compared to earlier designs.

The powerplant for the prototype was two 825 hp (615 kW) Pratt & Whitney R-1830-54 Twin Wasp engines mounted on the wing’s leading edges. Armament comprised four 0.30 in (7.62 mm) Browning machineguns and up to 2,000 lb (907 kg) of bombs.

The XP3Y-1 had its first flight on 28 March 1935 after which it was transferred to the US Navy for service trials. The XP3Y-1 soon proved to have significant performance improvements over current patrol flying boats. The Navy requested further development in order to bring the aircraft into the category of patrol bomber, and in October 1935 the prototype was returned to Consolidated for further work. The work included installation of 900 hp (671 kW) R-1830-64 engines. For the redesignated XPBY-1, Consolidated introduced redesigned vertical tail surfaces. The XPBY-1 had its maiden flight on 19 May 1936, during which a record non-stop distance flight of 3,443 miles (5,541 km) was achieved.

The XPBY-1 was delivered to VP-11F in October 1936. The second squadron to be equipped was VP-12, which received the first of its aircraft in early 1937. The second production order was placed on 25 July 1936. Over the next three years, the PBY design would be gradually improved and successive models introduced.