Liberty L-12

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Liberty L-12-1

See also Liberty L-8 for the eight-cylinder prototype & Lincoln Liberty engine

The Liberty L-12 was a 27 litre water-cooled 45 degree V-12 aircraft engine of 400 horsepower (300 kW). It was designed by Jesse Vincent and E. J. Hall of the Hall-Scott Motor Co. and manufactured by Packard, Lincoln, Ford, General Motors, and Nordyke and Marmon during the First World War. It was a modular design where 4 or 6 cylinders could be used in one or two banks. 20,478 were built between July 4 1917 and 1919. Displacing 1,649 cubic inches, bore was 5 inches (127 mm) and stroke 7 inches (178 mm). A single overhead camshaft for each cylinder bank operated 2 valves per cylinder, in a similar manner to the inline six cylinder German Mercedes D.III engine. Dry weight was 383 kg (844 lb) and takeoff power was 449 hp (335 kW) at 2,000 rpm. Two examples of a six-cylinder version, the Liberty L-6, were produced but not procured by the Army. Both were destroyed by Dr. William Christmas testing his so-called "Christmas Bullet" fighter. An inverted Liberty 12-A was also referred to as the V-1650 and was built up to 1926—the exact same designation later applied, due to identical displacement, to the World War II Packard-built Rolls-Royce Merlin. The engine was also produced in the UK for tank use as the Nuffield Liberty.

Specifications (Liberty L-12)

General characteristics

Type: 12-cylinder liquid-cooled Vee piston aircraft engine
Bore: 5 in (127 mm)
Stroke: 7 in (177.8 mm)
Displacement: 1,649.3 in³ (27 L)
Dry weight: 845 lb (383 kg)

Components

Valvetrain: One intake and one exhaust valves per cylinder operated via a single overhead camshaft per cylinder bank
Cooling system: Liquid-cooled