Ranger V 770

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. By 1941 a more developed V-770 was installed in the Fairchild XAT-14 Gunner prototype and was used in the production Fairchild AT-21 Gunner gunnery school aircraft.

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 very few Army Air Forces 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 light-weight 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.

SGV-770C-1

Tested in the Curtiss XF6C-7 Hawk Fighter-Bomber at 350 hp.

SGV-770C-B1

Installed in the Ikarus 214 prototype

SGV-770D-5

Developed for post-war commercial use, 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)

Applications

Bell XP-77

Curtiss SO3C

Edo OSE

Fairchild F-46 (Duramold)

Fairchild AT-21

Fairchild BQ-3

Ikarus 212

Ikarus 213 / Utva 213 Vihor / Government Factories Type 213 Vihor

Ikarus 214 (prototype)

Vought XSO2U

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 (101.6 mm)

Stroke: 5  ¹⁄₈ 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)

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, 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

Performance

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

Survivors

Carolinas Aviation Museum 1 restored engine in storage

2 engines in the Davis Aircraft private collection*

One survives at Cincinnati State Aviation school

One V770-7 is at the Museum of Flight restoration center.