Allison V-3420
The Allison V-3420 was a large experimental W-configuration American piston aircraft engine, designed in 1937.
History
In 1937, at the behest of the United States Army Air Corps, the Allison Engine Company agreed to design and build a large-displacement high power aircraft engine. The resulting V-3420 was essentially a pair of 12 cylinder Allison V-1710 engines mated to a common crankcase with a 30° angle between the inner cylinder banks. The crankshafts of the two V-1710 engines were geared together to drive a common propeller shaft. Most V-3420 parts were interchangeable with those for V-1710-E and -F engines.
The V-3420 had a power-to-weight ratio of 1.6 kW/kg or 1 hp/lb, excellent for its time. It was envisioned as a powerful yet compact engine for several advanced Air Force projects of the day, including the Douglas XB-19, the Boeing XB-39 Superfortress, the Lockheed XP-58 Chain Lightning, and the General Motors P-75 Eagle. As none of these designs reached full-scale production, only about 150 V-3420s were built.
Specifications (V-3420)
General characteristics
- Type: 24-cylinder turbosupercharged double-"Vee" liquid-cooled piston engine
- Bore: 5.5 in (139.7 mm)
- Stroke: 6 in (152.4 mm)
- Displacement: 3,421.2 in³ (56.06 L)
- Length: 100.0 in (2,540 mm)
- Width: 56.0 in (1,422 mm)
- Height: 34.0 in (864 mm)
- Dry weight: 2,600 lb (1,180 kg)
Components
- Valvetrain: Single overhead camshaft per 6-cylinder block, two intake and two exhaust valves per cylinder, sodium-cooled exhaust valves.
- Supercharger: Single-speed one-stage gear-driven supercharger
- Turbocharger: General Electric
- Fuel system: Bendix-Stromberg PT-12E1 three-barrel injection-type downdraft with automatic mixture control.
- Cooling system: Liquid-cooled with a mixture of 70% water and 30% ethylene glycol, pressurized.
Performance
- Power output:
- 2,600 hp (1,940 kW) at 3,000 rpm at 25,000 ft (7,625 m) for 15 minutes
- 2,100 hp (1,565 kW) at 2,600 rpm at 25,000 ft (7,625 m) maximum continuous power
- Specific power: 0.76 hp/in³ (34.6 kW/L)
- Compression ratio: 6.65:1
- Power-to-weight ratio: 1.0 hp/lb (1.64 kW/kg)
See also
- Related development
- Comparable engines
- Related lists
References
- Bridgman, L, (ed.) (1998) Jane's fighting aircraft of World War II. Crescent. ISBN 978-0-517-67964-7
External links
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