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Preserved Ranger V-770

The Ranger V-770 was an American air-cooled inverted V-12 aero-engine developed by the Ranger Aircraft Engine Division of the Fairchild Engine & Aircraft Corporation in the early 1930s.[2]

Design and development[]

In 1931, the V-770 design was put to paper, based on 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 and found to be unreliable with a tendency to overheat in low-speed flight.[3][4] By 1941 a more developed V-770 was installed in the Fairchild XAT-14 Gunner prototype and found satisfactory for the production Fairchild AT-21 Gunner gunnery school aircraft.[5]

Produced from 1941 to 1945, the V-770 featured a two-piece aluminum alloy crankcase, steel barreled cylinders with integral aluminum alloy fins and aluminum alloy heads. The V-770 was the only American inverted V12-type inline air-cooled engine to reach production. The engine was used in a relatively small number of Army Air Forces aircraft, among them the Fairchild AT-21 twin-engine trainer of which approximately 175 were built,[1] and in the two Bell XP-77s.


Installed in the Vought XSO2U-1 Scout
Installed in the XAT-14 Gunner prototype, intended for the Ryan SOR-1 Scout
Installed in the Bell XP-77 light-weight fighter prototype
Installed in the Curtiss SO3C Seamew Scout.[4]
Installed in the XAT-6E Texan prototype.[5]
Installed in the Fairchild AT-21 Gunner.[5]
Installed in the Fairchild AT-21 Gunner.[5]
Tested in the Curtiss XF6C-7 Hawk Fighter-Bomber at 350 hp.[4]
Developed for post-war commercial use,[2] 700 hp (kW) at 3,600 RPM, weight 870 lb (395 kg), height 31.11 in (790 mm), length 74.92 in (1,900 mm), width 33.28 in (846 mm)


Specifications (SGV-770C-1)[]

Data from Janes Fighting Aircraft of World War II (1989) [2]

General characteristics

  • Type: 12-cylinder inverted Vee piston engine
  • Bore: 4 in (101.6 mm)
  • Stroke: 5 18 in (130.2 mm)
  • Displacement: 773 in3 (12.6 L)
  • Length: 62 in (1,574.8 mm)
  • Width: 28 in (711.2 mm)
  • Height: 32.2 in (817.88 mm)
  • Dry weight: 730 lb (331 kg)


  • Valvetrain: Two overhead camshafts, one per cylinder bank, gear driven
  • Supercharger: Single-Speed, Single-Stage, produced 45 inches of mercury (1.5 bar, 7.5 psi) at take-off
  • Fuel system: Holley non-icing carburetor
  • Fuel type: 87 octane petrol
  • Oil system: Full pressure type
  • Cooling system: Air-cooled


  • Power output: 520 hp at 3,150 rpm (387.7 kW)
  • Specific power: 0.673 hp/in3
  • Compression ratio: 6.5:1
  • Power-to-weight ratio: 0.71 hp/lb


See also[]

  • Argus As 410
  • Argus As 411
  • de Havilland Gipsy Twelve
  • Isotta Fraschini Delta
  • Walter Sagitta


  1. 1.0 1.1 "Ranger V-770 Inverted". National Museum of the USAF. Retrieved 2008-11-07.  Includes photo
  2. 2.0 2.1 2.2 Jane, Frederick Thomas; Bridgman, Leonard; Gunston, Bill (1989). 0-517-67964-7 "Jane's Fighting Aircraft of World War II". London: Random House. ISBN 1-85170-493-0. 0-517-67964-7. 
  3. Smith, Herschel H. (1986). "Aircraft Piston Engines: From the Manly Balzer to the Continental Tiara". Sunflower University Press. ISBN 978-0-89745-079-9. [dead link]
  4. 4.0 4.1 4.2 Eden, Paul; Moeng, Soph (2002). "The Complete Encyclopedia of World Aircraft". London: Amber Books. ISBN 978-0-7607-3432-2. 
  5. 5.0 5.1 5.2 5.3 Swanborough, F. G.; Bowers, Peter M. (1964). "United States Military Aircraft Since 1909". New York: Putnam. ISBN 0-85177-816-X. 

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