Grace's Guide

British Industrial History

Grace's Guide is the leading source of historical information on industry and manufacturing in Britain. This web publication contains 137,257 pages of information and 220,097 images on early companies, their products and the people who designed and built them.


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1910. 200hp 8-cylinder engine.
1910. Monoplane.
November 1912.
Type 9B. 130 hp. 16.29 litres. Exhibit at the Fleet Air Arm Museum.
Type 9B. 130 hp. 16.29 litres. Exhibit at the Fleet Air Arm Museum.

The Clerget was an early aircraft engine. Manufactured in both Great Britain and France, it was used on such aircraft as the Sopwith Camel.

The Clerget is an air-cooled rotary engine with nine cylinders, 120 mm by 160 mm, rated at 110 hp (82 kW), but capable of developing 130 hp (97 kW) at 1,200 rpm. It is fitted with a double thrust ball race, which enables it to be used either as a pusher or as a tractor.

The engine works on a four-stroke cycle. Its chief points of difference from other rotary engines are:

  • The pistons are of an aluminium alloy.
  • The connecting rods have a tubular section.
  • The inlet and exhaust cams are mechanically operated by means of separate cams, tappets and rocker arms.
  • The direction of rotation is counter-clockwise as seen from the propeller end of the engine. Like many other radial engines it is made chiefly of steel, for strength and lightness. Between any two consecutive explosions, the engine turns 80 degrees.


  • Approx oil consumption: 2 imp gal/h (9 L/h)
  • Approx petrol consumption: 10 imp gal/h (45 L/h)

Approx weight of engine: 365 lb (166 kg), i.e. 3.3 lb per rated hp (2 kg/kW) (0.36hp/lb)

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