|Preserved Bristol Centaurus engine|
|Type||Piston aircraft engine|
|Manufacturer||Bristol Aeroplane Company|
|First run||July 1938|
|Major applications||Hawker Tempest
Hawker Sea Fury
The Centaurus was the final development of the Bristol Engine Company's series of sleeve valve radial aircraft engines, an 18-cylinder, two-row design that eventually delivered over 3,000 hp (2,200 kW). It was one of the largest aircraft piston engines to enter production, and was introduced into service use towards the end of World War II.
Design and development
Like most Bristol Engines designs, the Centaurus was based on the mechanicals of an earlier design, in this case the "classic" 5.75 in (146 mm) piston from their original 1918 Jupiter. The Jupiter piston was still in use in the contemporary 14-cylinder Hercules, which was being brought into production during the design of the Centaurus. The Centaurus had a cylinder capacity of 3,270 in³ (53.6 l), making it one of the largest aircraft piston engines to enter production, while that of the Hercules was 2,364 cubic inches (38.7 l). The nearly 40% higher capacity was achieved by increasing the stroke from 6.5 to 7 in (170 to 180 mm), and by changing to two rows of nine cylinders instead of two rows of seven, but the overall diameter of the Centaurus was only just over 6% greater.
While Bristol maintained the Centaurus dated from 1938 (the year it was originally type-tested), production could not start until 1942 owing to the need to get the Hercules into production and improve the reliability of the entire engine line. Nor was there any real need for the larger engine at this early point in the war, when most military aircraft designs were intended to mount engines of 1,000 hp or a little more. The Hercules' approximately 1,500 hp was simply better suited to the existing airframes then in production.
In fact, the Centaurus did not see any use until near the end of the war, first appearing on an upscaled version of the Vickers Wellington, the Warwick. Other wartime, or just-postwar, applications included the Bristol Brigand and Buckmaster, Hawker Tempest and Sea Fury, and the Blackburn Firebrand and Beverley. The engine also saw post-war use in civilian airliners, including the ill-fated Bristol Brabazon.
By the end of the war in Europe, around 2,500 examples of the Centaurus had been produced by Bristol.
The most powerful version of the Centaurus developed was intended for the Blackburn Beverley transport aircraft. Utilising direct injection, it achieved a remarkable 3,220 hp, but was never fitted. 
A projected enlarged capacity version of the Centaurus was designed by Roy Fedden, cylinders were produced for this engine but it was never built. Known as the Bristol Orion (a name used previously for a variant of the Jupiter engine, and later re-used for a turboprop one) this development was also a two-row, 18 cylinder sleeve valve engine with the displacement increased to 4,142 cubic inches (67.9 l).
The Centaurus was produced in 34 variants ranging from the 2,000 hp (1,490 kW) Centaurus I to the 2,405 hp (1,793 kW) Centaurus 663 for the Airspeed Ambassador airliner. The most powerful variants to enter service were the 2,625 hp (1,957 kW) Centaurus 170, 173, 660, 661 and 662.
Engines on display
Preserved Bristol Centaurus engines are on public display at the following museums:
- Aerospace Museum of California
- Fleet Air Arm Museum
- Imperial War Museum Duxford
- London Science Museum
- Midland Air Museum
- Shuttleworth Collection, Old Warden
Specifications (Centaurus VII)
Data from Lumsden
- Type: 18-cylinder, air-cooled, two-row radial engine
- Bore: 5.75 in (146 mm)
- Stroke: 7 in (177 mm)
- Displacement: 3,270 in³ (53.6 l)
- Diameter: 55.3 in (1,405 mm)
- Dry weight: 2,695 lb (1,223 kg)
- Valvetrain: Sleeve valve, four ports per sleeve
- Supercharger: Two-speed centrifugal, single stage
- Fuel system: Injection
- Fuel type: 100/130 Octane petrol
- Oil system: Direct-pressure lubrication
- Cooling system: Air-cooled
- Power output: 2,520 hp (1,880 kW) at 2,700 rpm
- Specific power: 0.77 hp/in³ (35.1 kW/l)
- Compression ratio: 7.2:1
- Power-to-weight ratio: 0.94 hp/lb (1.54 kW/kg)
- Related development
- Comparable engines
- Related lists
- Bridgman, L, (ed.) (1998) Jane's Fighting Aircraft of World War II. Crescent. ISBN 0-517-67964-7
- Gunston, Bill. Development of Piston Aero Engines. Cambridge, England. Patrick Stephens Limited, 2006. ISBN 0-7509-4478-1
- Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9
- Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6.
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