Allison V-3420

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.

pecifications (V-3420)

pistonspecs

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)
weight=2,600 lb (1,180 kg)
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
fuelsystem=Bendix-Stromberg PT-12E1 three-barrel injection-type downdraft with automatic mixture control.
fueltype=
oilsystem=
coolingsystem=Liquid-cooled with a mixture of 70% water and 30% ethylene glycol, pressurized.
power=
*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
specpower=0.76 hp/in³ (34.6 kW/L)
compression=6.65:1
fuelcon=
specfuelcon=
oilcon=
power/weight=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

Related contents

* Allison V-1710