On December 20, 1944, the US Navy's Bureau of Aeronautics initiated a requirement for a maritime patrol flying boat powered by four Pratt & Whitney R-2800 Double Wasp radial piston engines and carrying 4,000 lb (1,814 kg) of bombs, which would be used for anti-submarine warfare, anti-shipping missions, and search-and-rescue. Convair, Hughes, and Martin submitted bids in early 1945, and the Convair design proposed in January 1945 had four 2,100 hp (1,544 kW) Pratt & Whitney R-2800C-14 radial piston engines, a gross weight of 105,000 lb (47,628 kg), and a crew of seven (pilot, co-pilot, navigator/bombardier, radar operator, radio operator, flight engineer, and countermeasures operator). An alternate design was proposed with four 5,000 shp (3,677 kW) Wright turboprop engines and a gross weight of 140,000 lb (63,502 kg). Both designs had a wing area of 2,625 ft2 (243.87 m2) and armament for these designs comprised eight .50 caliber machine guns in four turrets (one nose turret, two waist turrets, and one tail turret) and either four 1,000 lb (453 kg) bombs, two 2,000 lb (907 kg) bombs, four 400 lb (181 kg) bombs, twelve 325 lb (147 kg) depth charges, or six 657 lb (298 kg) depth charges in internal weapons bays in the wings.
The last Convair flying boat design to receive a US Navy designation was the Convair Model 24, designated P6Y. Aware of the pitfalls of its traditional anti-submarine warfare capabilities, Convair beginning in October 1953 explored the notion of an ASW flying boat with the capability to use dunking sonar, even constructing a large free-flight model nicknamed the "Dunker", tested in late 1955 and early 1956 (Bradley 2010, p. 99). On May 21, 1956 the US Navy issued a Request for Proposals for an ASW flying boat able to use dunking sonar to track enemy submarines. Convair responded with the Model 24, a high-wing seaplane with three Wright R-3350 Duplex Cyclones (two outboard, one above the fuselage), a boundary layer control system powered by two General Electric J85 turbojets situated behind the outboard piston engines, a wingspan of 127 feet 6 inches, a gross weight of 107,648 pounds, and a crew of 10 (Buttler 2010, pp. 152-153). (Grumman and Martin's submissions for the Class VP requirement were the G-132 and Martin Model 313/P7M respectively.) Despite falling short of the performance parameters in the requirement, the Model 24 was judged by the Navy to be superior to the Grumman and Martin designs, and in November 1956 the Navy selected the Convair design and allocated it the designation XP6Y-1. Two prototypes were ordered in February 1957, but members of the US Navy top brass who had experience with flying seaplanes were not too enthusiastic about the P6Y, viewing the operational environment of the dunking sonar seaplane concept fairly dangerous and highly uncomfortable. As a result of this criticism, the P6Y program was canceled before any of the prototypes were built (Bradley 2010, p. 102).
References:
Bradley, R., 2010. Convair Advanced Designs: Secret Projects from San Diego 1923-1962. North Branch, MN: Specialty Press.
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| Top: A desktop model of the R3Y-1 Tradewind at the Planes of Fame Museum, photographed by me in January 2018. Bottom left: The first XP5Y-1 prototype (BuNo 121455) taking off for its first flight on April 15, 1950. Bottom right: An R3Y-1 Tradewind flying low over San Francisco Bay near Alameda NAS |
As 1945 progressed, the BuAer decided that the performance parameters jotted out in the December 1944 specification for a new four-engine patrol flying boat only offered marginal improvement over that of the Consolidated PB2Y and Martin PB2M/JRM Mars, so the idea of a brand new flying boat with R-2800s was instantly abandoned and Convair's design solicitations were not proceeded with. and However, the Navy still wanted a new flying boat able to perform the operational roles specified in the December 1944 requirement, and on December 27, 1945, the Navy's Bureau of Aeronautics (BuAer) issued a specification for a new-generation maritime patrol flying boat designed to use gas turbine engines. Convair, Hughes, and Martin submitted bids for turboprop flying boat designs, and the Navy selected Convair's Model 117 design, assigning it the designation XP5Y-1. Technical details of the P5Y and its transport derivative, the R3Y Tradewind, have been covered in Bradley (2010, pp. 65-68, pp. 82-85), so will not be wastefully replicated here, except to say that the P5Y/R3Y series used four Allison T40 turboprops driving counter-rotating propellers. Two XP5Y-1 prototypes were ordered on May 27, 1946, and the first prototype flew on April 18, 1950 (the second prototype never flew). However, by the time of the P5Y's first flight the Navy gave up on turboprop-powered patrol flying boats and ordered Convair to rework the P5Y design as a transport aircraft to replace the Martin JRM Mars, leading to the R3Y Tradewind (designated Model 3 by Convair), the first flight of which occurred on February 22, 1954. Eleven R3Ys were built, with the baseline R3Y-1 version retaining the nose of the XP5Y-1 and the the R3Y-2 version with a lifting nose similar to that of the Lockheed C-5 Galaxy. Unfortunately, the T40 used on the Tradewind suffered teething troubles, and when one R3Y-1 was lost en route to Alameda, California on January 24, 1958, the Navy ordered all R3Ys removed from active service and sold for scrap.
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Left: 3-view drawing of the Convair P6Y dunking sonar ASW flying boat from the Convair project documents
Right: A company scale model of the Convair P6Y
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The last Convair flying boat design to receive a US Navy designation was the Convair Model 24, designated P6Y. Aware of the pitfalls of its traditional anti-submarine warfare capabilities, Convair beginning in October 1953 explored the notion of an ASW flying boat with the capability to use dunking sonar, even constructing a large free-flight model nicknamed the "Dunker", tested in late 1955 and early 1956 (Bradley 2010, p. 99). On May 21, 1956 the US Navy issued a Request for Proposals for an ASW flying boat able to use dunking sonar to track enemy submarines. Convair responded with the Model 24, a high-wing seaplane with three Wright R-3350 Duplex Cyclones (two outboard, one above the fuselage), a boundary layer control system powered by two General Electric J85 turbojets situated behind the outboard piston engines, a wingspan of 127 feet 6 inches, a gross weight of 107,648 pounds, and a crew of 10 (Buttler 2010, pp. 152-153). (Grumman and Martin's submissions for the Class VP requirement were the G-132 and Martin Model 313/P7M respectively.) Despite falling short of the performance parameters in the requirement, the Model 24 was judged by the Navy to be superior to the Grumman and Martin designs, and in November 1956 the Navy selected the Convair design and allocated it the designation XP6Y-1. Two prototypes were ordered in February 1957, but members of the US Navy top brass who had experience with flying seaplanes were not too enthusiastic about the P6Y, viewing the operational environment of the dunking sonar seaplane concept fairly dangerous and highly uncomfortable. As a result of this criticism, the P6Y program was canceled before any of the prototypes were built (Bradley 2010, p. 102).
References:
Bradley, R., 2010. Convair Advanced Designs: Secret Projects from San Diego 1923-1962. North Branch, MN: Specialty Press.
Buttler, T., 2010. American Secret Projects: Bombers, Attack, and Anti-Submarine Aircraft 1945-1974. Hersham, UK: Ian Allan Publishing.
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