The Clerget 9B was a nine-cylinder rotary aircraft engine of the World War I era designed by Pierre Clerget. Manufactured in both France and Great Britain (Gwynnes Limited), it was used on such aircraft as the Sopwith Camel. The Clerget 9Bf was an increased stroke version.
Clerget 9B(1913) 130 hp (97 kW). 1,300 produced by Ruston Proctor & Co Ltd of Lincoln
Clerget 9Bf(1915) 140 hp (104 kW). Extended stroke (172 mm (6.75 in)) version, increasing capacity to 17.5 L (1,066.5 cu in). 1,750 produced by Gwynnes Limited and 600 produced by Ruston Proctor.
Armstrong Whitworth F.K.10Avro 504Avro 531Bristol M.1Cierva C.6Cierva C.8Fairey Hamble BabyFBA Type CNieuport 12Nieuport 17bisSopwith BabySopwith CamelSopwith ScooterSopwith TriplaneSopwith 1½ StrutterSopwith CamelA preserved Clerget 9B engine is on public display at the Fleet Air Arm Museum, RNAS Yeovilton.A Clerget 9Bf engine is on display at the Powerhouse Museum, Sydney.Data from Lumsden.
Type: Nine-cylinder air-cooled rotary engineBore: 120 mm (4.72 in)Stroke: 9B: 160 mm (6.30 in), 9Bf: 172 mm (6.77 in)Displacement: 9B: 16.29 l (994.08 cu in), 9Bf: 17.5 l (1,067.92 cu in)Length: 920 mm (36.22 in)Diameter: 9B: 1,020 mm (40.15 in), 9Bf: 1,030 mm (40.55 in)Dry weight: 173 kg (381 lb)Valvetrain: Single inlet and exhaust valves operated by pushrods and rockersFuel system: Bloctube carburettorFuel type: Gasoline mixed with Castor oil lubricantOil system: Castor oil mixed with fuelCooling system: Air-cooledPower output: 9B: 96.94 kW (130 hp) at 1,250 rpm, 9Bf: 104.40 kW (140 hp) at 1,250 rpmSpecific power: 9B: 0.1308 hp/cu in (5.953 kW/l), 9Bf: 0.131 hp/cu in (5.966 kW/l)Compression ratio: 9B: 4.56:1, 9Bf: 5.3:1Specific fuel consumption: 9B: 0.564 l/kW/hour(0.74 pt/hp/hour), 9Bf: 0.45 l/kW/hour(0.59 pt/hp/hour)Oil consumption: 9B: 0.0686 l/kW/hour (0.09 0.11 pt/hp/hour), 9Bf: 0.0838 l/kW/hour (0.11 pt/hp/hour)Power-to-weight ratio: 9B: 0.563 kW/kg (0.341 hp/lb), 9Bf: 0.556 kW/kg (0.337 hp/lb) 
