Ranger V-770

The Ranger V-770 was an American air-cooled inverted V-12 aircraft engine developed by the Ranger Aircraft Engine Division of the Fairchild Engine & Aircraft Corporation in the early 1930s.^[1]

V-770
Preserved Ranger V-770
Type	Piston aero-engine
Manufacturer	Ranger Aircraft Engine Division
First run	1931
Major applications	Curtiss SO3C Seamew

Design and development

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.

Variants

V-770-7 in Bell XP-77 mockup

V-770-4

Installed in the Vought XSO2U-1 scout aircraft

V-770-6

Installed in the Fairchild XAT-14 Gunner prototype, intended for the Ryan SOR-1 Scout

V-770-7

Installed in the Bell XP-77 lightweight fighter prototype

V-770-8

Installed in the Curtiss SO3C Seamew Scout.^[3]

V-770-9

Installed in the North American XAT-6E Texan prototype.^[5]

V-770-11

Installed in the Fairchild AT-21 Gunner.^[5]

V-770-15

Installed in the Fairchild AT-21 Gunner.^[5]

V-770-17

Similar to V-770-8 but with raised hollow propeller shaft for mounting cannon or machine gun.

GV-770

Geared un-supercharged variants.^[7]

SV-770

Supercharged direct-drive variants.^[7]

SGV-770

Supercharged and geared variants.^[7]

SGV-770C-1

Tested in the Curtiss XF6C-7 Hawk fighter-bomber at 350 hp (260 kW).^[3]

SGV-770C-1B

(V-770-11)

SGV-770C-2A

(V-770-8)

SGV-770C-B1

Installed in the Ikarus 214 prototype

SGV-770D-4

(V-770-17) Similar to C-2A but with raised hollow propeller shaft for mounting cannon or machine gun.

SGV-770D-5

Developed for post-war commercial use,^[1] 700 hp (520 kW) at 3,600 RPM, weight 870 lb (390 kg), height 31.11 in (790 mm), length 74.92 in (1,903 mm), width 33.28 in (845 mm)

Applications

• AEKKEA-RAAB R-29
• Bell XP-77
• Curtiss SO3C Seamew
• Edo OSE
• Fairchild F-46
• Fairchild AT-21 Gunner
• Fairchild BQ-3
• Ikarus 213/Utva 213 Vihor
• Ikarus 214 (prototype)
• Vought XSO2U
• North American XAT-6E

Engines on display

• One restored engine in storage at the Carolinas Aviation Museum
• One survives at Cincinnati State Aviation school
• One modified V-770 survives in an art car by Michael Leeds^[8]
• The Yankee Air Museum has a V-770 on display.
• One restored engine at the Vintage Flying Museum in Fort Worth.

Specifications (SGV-770C-1)

The Ranger V-770 engine as viewed along the cylinders.

Data from Janes Fighting Aircraft of World War II (1989).^[1]

General characteristics

• Type: 12-cylinder inverted Vee piston engine
• Bore: 4 in (102 mm)
• Stroke: 5.125 in (130 mm)
• Displacement: 773 cu in (12.7 L)
• Length: 62 in (1,575 mm)
• Width: 28 in (711 mm)
• Height: 32.2 in (818 mm)
• Dry weight: 730 lb (330 kg)

Components

• Valvetrain: Single overhead camshaft (SOHC) (1 shaft per bank), gear driven
• Supercharger: Single-speed, single-stage, produced 45 inches of mercury (1.5 bar, 22 psi) at take-off
• Fuel system: Holley non-icing carburetor
• Fuel type: 87 octane gasoline
• Oil system: Full pressure type
• Cooling system: Air-cooled

Performance

• Power output: 520 hp (390 kW) at 3,150 rpm
• Specific power: 0.68 hp/in³
• Compression ratio: 6.5:1
• Power-to-weight ratio: 0.71 hp/lb

See also

Comparable engines

• Argus As 410
• Argus As 411
• de Havilland Gipsy Twelve
• Walter Sagitta

Related lists

• List of aircraft engines

References

1. Jane, Frederick Thomas; Bridgman, Leonard; Gunston, Bill (1989), Jane's Fighting Aircraft of World War II, London: Random House, ISBN 1-85170-493-0
2. Smith, Herschel H. (1986), Aircraft Piston Engines: From the Manly Balzer to the Continental Tiara, SunflowerUniversity Press, p. 255, ISBN 978-0-89745-079-9, OCLC 14253144
3. Eden, Paul; Moeng, Soph (2002), The Complete Encyclopedia of World Aircraft, London: Amber Books, ISBN 978-0-7607-3432-2
4. Adcock, Al (1991). OS2U Kingfisher in action. Aircraft In Action. Vol. 119. Carrollton, TX: Squadron/Signal Publications. p. 44. ISBN 0-89747-270-5.
5. Swanborough, F. G.; Bowers, Peter M. (1964), United States Military Aircraft Since 1909, New York: Putnam, ISBN 0-85177-816-X
6. "Ranger V-770 Inverted". National Museum of the USAF. Archived from the original on 30 December 2008. Retrieved 7 November 2008.
7. Bridgman, Leonard (1937). Grey, C.G. (ed.). Jane's all the World's Aircraft 1937. London: Sampson Low, Marston & Co. Ltd.
8. Blown Ranger