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Napier Nomad Model E. 145 Horizontally-Opposed Diesel Engine


Display Status:

This object is on display in the Boeing Aviation Hangar room at Steven F. Udvar-Hazy Center in Chantilly, VA.

Napier Nomad Model E. 145 Horizontally-Opposed Diesel Engine

Collection Item Summary:

D. Napier and Son began building aircraft engines in the World War I era. The Lion series was produced from 1917 until 1932 for military, commercial, and racing aircraft. Napier’s World War II era Sabre engines also powered a number of aircraft. Intended for use in long-range aircraft at the end of World War II, the Nomad was an engineering tour-de-force, although being one of the most complex aircraft engines ever built. Napier designed the Nomad to have the lowest possible fuel consumption by compounding a two-stroke diesel engine with a gas turbine and transmitting the power through a propeller.

The Nomad II, a simplified version of the original design, appeared in 1951 and was intended for the four-engine Avro Shackleton long-range patrol bomber. However, a single Nomad II flew only briefly, in the nose of an Avro Lincoln bomber. Napier cancelled the program in 1955 because the Nomad could not compete with gas turbine engines.

Collection Item Long Description:

Data Source

National Air and Space Museum


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


Ernest Chatterton

Credit Line

Gift of Napier Aero Engines Ltd.


Length 302.9 cm (119.25 in.), Width 142.9 cm (56.25 in.), Height 101.6 cm (40.0 in.)

Country of Origin

United Kingdom



Physical Description

  • Type: Reciprocating, horizontally-opposed, diesel, 12 cylinder, liquid cooled
  • Power rating: 2,271 kW (3,046 hp) at 2,050 rpm
  • Displacement: 41.1 L (2,505 cu in.)
  • Bore and Stroke: 152 mm (6 in.) x 187 mm (7.4 in.)
  • Weight: 1,625 kg (3,580 lb)


PROPULSION-Reciprocating & Rotary

Inventory Number