The Clerget 9B version 2 represents the refined evolution of one of World War I’s most important rotary aircraft engines. Introduced after early operational experience with the initial 9B, version 2 incorporated practical improvements aimed at better reliability, smoother running, and improved pilot control—while retaining the proven core design that made the 9B successful. This nine-cylinder, air-cooled rotary engine produced around 130 horsepower, delivering strong performance for frontline fighters of 1916–1917. Subtle mechanical updates—most notably to carburation, valve timing, and internal tolerances—helped reduce fuel irregularities and improve overall consistency in service. These refinements made the engine more forgiving to operate, especially under combat conditions. Like all rotary engines, the Clerget 9B version 2 rotated with the propeller, ensuring excellent cooling and a distinctive handling character that skilled pilots learned to exploit. The engine powered aircraft such as the Sopwith Camel, Sopwith Pup, and various Nieuport types, playing a key role in the rapid advancement of Allied air capability during the middle years of the war.
