What is Allison V-3420?

Information about Allison V-3420

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Allison V-3420 Engine
The Allison V-3420 was a large experimental 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 (140 mm)
  • Stroke: 6 in (152 mm)
  • Displacement: 3,420 in³ (56 L)
  • Length: 100.0 in (2,540 mm)
  • Diameter:
  • 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)

References

  • Bridgman, L, (ed.) (1998) Jane's fighting aircraft of World War II. Crescent. ISBN 978-0-517-67964-7

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The Allison Engine Company was a U.S. aircraft engine manufacturer which was acquired by Rolls-Royce plc in 1995 to become a subsidiary, Rolls-Royce Corporation.

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Type Heavy bomber
Manufacturer Douglas Aircraft
Maiden flight 27 June 1941
Retired Scrapped in 1949
Status Experimental
Primary user U.S.
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Type Test-bed bomber aircraft
Manufacturer Boeing
Maiden flight 1944
Introduced n/a
Status Never mass-produced
Primary user United States Army Air Forces
Produced 1944
Number built 1 The
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Type Heavy fighter
Manufacturer Lockheed
Maiden flight 1 June 1944
Status Cancelled
Number built 1

The Lockheed XP-58 Chain Lightning was an American long-range fighter developed during World War II.
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Type Fighter
Manufacturer General Motors Corporation
Maiden flight 17 November 1943
Status Cancelled 6 October 1944
Number built 6

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