The Clerget 9B was a nine-cylinder rotary aircraft engine of the World War I era and was designed by the Frenchman Pierre Clerget.  This engine was manufactured in both Great Britain (Gwynne Limited) and France and was used on such aircraft as the Sopwith Camel.

 The Sopwith Camel was a British First World War single-seat biplane fighter introduced on the Western Front during 1917.  Manufactured by Sopwith Aviation Company, it had a short-coupled fuselage, a heavy and powerful nine-cylinder powerful rotary engine could deliver concentrated fire from twin synchronized .303 Vickers machine guns.

Though difficult to handle, to an experienced pilot it provided unmatched manoeuvrability with a very swift right hand turn due to the torque of the rotary engine.  A superlative fighter, the Sopwith Camel was credited with shooting down 1 294 enemy aircraft, more than any other Allied fighter of the war.  It also served as a ground-attack aircraft, especially near the end of the conflict when it was outclassed in the air-to-air role by newer Imperial German fighters.