The 130 horsepower (97 kW) Clerget 9B was an important engine for the British Royal Naval Air Service and Royal Flying Corps, being license-produced in Britain and powering a number of important British aircraft, including the Sopwith Camel. However, at £907 a copy it was expensive, and prone to overheating, so the Admiralty asked Lieutenant W. O. Bentley, an established pre-war engine designer,[1] to produce a modified version to solve these problems.[2]