In 1931, the V-770 design was built, derived from the Ranger 6-440 series of inverted inline air-cooled engines, and test flown in the Vought XSO2U-1 Scout. In 1938 it was tested in the Curtiss SO3C Seamew but was found to be unreliable with a tendency to overheat in low-speed flight, but would still be the most produced aircraft to have the V-770, with 795 being built.[2][3] Its competitor Vought XSO2U also suffered from overheating problems that were never satisfactorily solved.[4]
By 1941 a more developed V-770 was installed in the Fairchild XAT-14 Gunner prototype gunnery school aircraft, which went into limited production as the Fairchild AT-21 Gunner, of which 174 were built, not including one radial engine prototype.[5]
Produced from 1941 to 1945, the V-770 featured a two-piece aluminum alloy crankcase, steel cylinder barrels with integral aluminum alloy fins and aluminum alloy heads. The V-770 was the only American inverted V-12 air-cooled engine to reach production. The engine was used in very few aircraft, among them the short lived Fairchild AT-21 twin-engine bomber trainer,[6] and in the two Bell XP-77 light-weight fighter prototypes.
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123Jane, Frederick Thomas; Bridgman, Leonard; Gunston, Bill (1989), Jane's Fighting Aircraft of World War II, London: Random House, ISBN1-85170-493-0
↑Smith, Herschel H. (1986), Aircraft Piston Engines: From the Manly Balzer to the Continental Tiara, SunflowerUniversity Press, p.255, ISBN978-0-89745-079-9, OCLC14253144
