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Humber Ltd. (Bentley) B.R.2, Rotary 9 Engine


Display Status:

This object is on display in the Legend, Memory and the Great War in the Air exhibition at the National Air and Space Museum in Washington, DC.

Collection Item Summary:

Initially asked in 1914 to study an overheating problem in rotary engines, Captain W. O. Bentley, an established car designer, developed a new and more efficient engine, with a weight-saving effect realized by careful design and the use of aluminum wherever possible. Equally important was the lower cost, as compared to the French Clerget, then widely used in British aircraft; and itself considered an improvement over the earlier Gnome

Following success of the smaller A.R.1 (Admiral Rotary 1), which was later renamed Model B.R.1 for Bentley Rotary 1, the larger B.R.2 rotary aircraft engine powered a variety of World War I aircraft, including, among others, the: Sopwith F.1 Camel and 7F.1 Snipe; Nieuport B.N.1; and Vickers F.B.26A Vampire II. Humber Ltd., one of five British companies that manufactured this model during World War I, built this Bentley B.R.2 artifact.

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


W. O. Bentley

Credit Line

Gift of Preston Kirk




  • 3-D: 102 × 106.7cm (40 3/16 × 42 in.)
  • Support: 71 × 108 × 79cm (27 15/16 in. × 42 1/2 in. × 31 1/8 in.)

Country of Origin

United Kingdom


Circa 1917

Physical Description

  • Type: Rotary, 9 cylinders, air-cooled
  • Power rating: 149 kW (200 hp) at 1,300 rpm
  • Displacement: 25.0 L (1,522.44 cu. in.)
  • Bore and Stroke: 140 mm (5.51 in) x 190 mm (7.09 in)
  • Weight (dry): Approx 227 kg (500 lb)


PROPULSION-Reciprocating & Rotary

Inventory Number