Ranger V-770



The Ranger V-770 was an American air-cooled inverted Vee aero-engine developed by the Ranger Aircraft Engine Division of the Fairchild Engine & Aircraft Corporation and first run in 1931.

In 1931, the V-770 design was put to paper, based on the Ranger 6-440 series of 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 found satisfactory for 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 one of very few V-type, in-line, air-cooled engines 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, and in the two Bell XP-77s.

By 1944, the unit cost was US$11,000


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.
Installed in the XAT-6E Texan prototype.

Installed in the Fairchild AT-21 Gunner.

Installed in the Fairchild AT-21 Gunner.
Tested in the Curtiss XF6C-7 Hawk Fighter-Bomber at 350 hp.
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)


Bell XP-77
Curtiss SO3C
Fairchild AT-21
Fairchild BQ-3
Ikarus 214D
Vought XSO2U




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)
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