# 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.

## 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. Its competitor Vought XSO2U also suffered from overheating problems that were never satisfactorily solved. 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.
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, and in the two Bell XP-77 light-weight fighter prototypes.

## Variants
### 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.

### V-770-9

    Installed in the North American XAT-6E Texan prototype.

### V-770-11

    Installed in the Fairchild AT-21 Gunner.

### V-770-15

    Installed in the Fairchild AT-21 Gunner.

### 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.

### SV-770

    Supercharged direct-drive variants.

### SGV-770

    Supercharged and geared variants.

### SGV-770C-1

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

### 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, 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
* 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)

Data from Janes Fighting Aircraft of World War II (1989).

### 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