The Clerget 9BF was a 9-cylinder rotary engine producing approximately 130–140 hp (97–104 kW). Designed and manufactured in France during World War I, it was widely used by Allied forces in fighter aircraft due to its combination of reliability, power, and relatively compact size. The 9BF was particularly popular in British aircraft, where it powered some of the most iconic late-war scouts.

Aircraft powered by the Clerget 9BF

• Sopwith Camel – many late-production Camels were fitted with the Clerget 9BF, providing strong performance, climb rate, and maneuverability.
• Sopwith Pup (late production variants and some experimental types) – although mostly powered by Le Rhône engines, some were fitted with Clerget 9BF for evaluation.
• Sopwith Triplane – later-production examples used the 9BF to improve performance and climb compared with earlier engines.
• Other Allied experimental aircraft – the 9BF was occasionally used in various experimental or small-scale projects where a 130–140 hp rotary was required.

Historical significance

The Clerget 9BF represented the peak of rotary engine design in terms of power and reliability during WWI. Its performance helped the Allies maintain air superiority in the final years of the war, particularly in nimble single-seat fighters like the Sopwith Camel and Snipe. While heavier and more fuel-hungry than smaller rotaries, the 9BF’s robustness and power-to-weight ratio made it one of the most successful rotary engines of the conflict.{{freeshipping_code_1}}{{payment}}