With an industrial history dating to the early nineteenth century, D. Napier and Son began building aircraft engines in the World War I era. Napier began work on a remarkable new engine, the Lion, in 1916. Its three banks of four cylinders formed a "W" or "Broad Arrow" configuration. The arrangement provided a much shorter crankcase, a stiffer and simpler crankshaft, and a more compact engine than the 12-cylinder "V" construction of other high-performance engines of the period.

Napier produced the reliable and widely used Lion series from 1917 until 1932 for military, commercial, and special-purpose racing aircraft. One especially notable application was the Supermarine S.5, which, powered by a 656 kW (880-hp) Lion VIIB engine, won the Schneider Trophy Race in 1927.

Although the Lion became uncompetitive for aviation after 1930, the Sea Lion marine version stayed in production for RAF rescue application until 1943.

 Display Status

This object is not on display at the National Air and Space Museum. It is either on loan or in storage.
Object Details
Date Circa 1919 Country of Origin United Kingdom Type PROPULSION-Reciprocating & Rotary Manufacturer Napier Aero Engines Ltd.
 Physical Description Type: Reciprocating, 12 cylinders, W-type (three banks of four cylinders), water-cooled Power rating: 336 kW (450 hp) at 2,000 rpm Displacement: 24 L (1,462 cu in.) Bore and Stroke: 140 mm (5.5 in.) x 130 mm (5.13 in.) Weight: 389.2 kg (858 lb) Dimensions Length 167.6 cm (66 in.), Width 121.9 cm (48 in.), Height 109.2 cm (43in.)
 Materials Aluminum
Steel
Paint
Rubber
Copper Alloy
 Inventory Number A19610134000 Credit Line Transferred from the U.S. Air Force, Wright-Patterson AFB, Ohio Data Source National Air and Space Museum Restrictions & Rights Usage conditions apply
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