Liberty 12 Model A, V-12 Engine


Display Status:

This object is not on display at the National Air and Space Museum. It is either on loan or in storage.

Collection Item Summary:

The Liberty engine was America's most important contribution to aeronautical technology during World War I. Jesse G. Vincent of Packard and Elbert J. Hall of Hall-Scott co-designed it between May 30 and June 4, 1917 for the U.S. government, which wanted a standard design in 4-, 6-, 8-, and 12-cylinder versions that could be quickly mass-produced to equip U.S. combat aircraft. To ensure a workable engine in the shortest possible time, they used only proven components, with features from both Hall-Scott and Packard. They succeeded, with the first 8-cylinder engine delivered in early July.

However, demand for lower-power engines was already being met, and wartime experience showed the need for high power. Liberty-12s powered many aircraft types, but most were built for the de Havilland DH-4. Automakers Ford, Lincoln, Packard, Marmon, and Buick produced 20,748 Liberty 12s, with varying quality, before the Armistice, which insured their widespread use into the 1920s and '30s.

Collection Item Long Description:


Circa 1918

Inventory Number


Physical Description

  • Type: Reciprocating, 12 cylinders, V-type, Liquid-cooled
  • Power rating: 298 kW (400 hp) at 1,800 rpm
  • Displacement: 27.0 L (1,648.92 cu in)
  • Bore and Stroke: 127 mm (5 in.) x 178 mm (7 in.)
  • Weight: 383 kg (844 lb)

Credit Line

Transferred from the U.S. Navy, Naval Supply Center, Cheatham Annex, Williamsburg, Virginia


  • Elbert J. Hall
  • Jesse G. Vincent



Country of Origin

United States of America


Steel, Aluminum, Rubber, Paint, Phonolic, Preservative coating, Brass, Copper


Height 105.4 cm (41.5 in.), Width 68.6 cm (27 in.), Depth 171.1 cm (67.375 in.)

Data Source

National Air and Space Museum

Restrictions & Rights

Do not reproduce without permission from the Smithsonian Institution, National Air and Space Museum


PROPULSION-Reciprocating & Rotary