Allison V-3420

V-3420
Allison V-3420 Engine
Type	Liquid-cooled W-24 piston engine
National origin	United States
Manufacturer	Allison Engine Company
First run	1937
Major applications	Fisher P-75 Eagle
Developed from	Allison V-1710

The Allison V-3420 was an American large experimental W-configuration American piston aircraft engine, designed in 1937.

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 Fisher P-75 Eagle. As none of these designs reached full-scale production, only about 150 V-3420s were built.

Data from Aircraft Engines of the world 1946

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