Bristol Centaurus

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 swept volume of 3,272 in³ (53.6 l), close to that of the American Wright Duplex-Cyclone large radial, making the Centaurus one of the largest aircraft piston engines to enter production, while that of the Hercules was 2,363 cubic inches (38.7 l). The nearly 40 percent 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 diameter of the Centaurus was only just over 6 percent greater.

The cylinder heads had an indentation like an inverted top hat, which of course was finned but it was difficult to get air down into this hollow to adequately cool the head. During the development stage the engineers contacted ICI Metals Division, Birmingham, to enquire whether a copper-chromium alloy with higher thermal conductivity, would have sufficient high temperature strength to be used for this purpose. Tests were successful and with the same volume of cylinder, these modified heads enabled the horsepower per cylinder to be raised from 110hp to 220hp.

Bristol maintained the Centaurus from type-testing in 1938 but production did 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 around 1,000 hp. The Hercules' approximately 1,500 hp was better suited to the existing airframes.

The Centaurus did not see service until near the end of the war, first appearing on the Vickers Warwick. Other wartime, or just-postwar, uses included the Bristol Brigand and Buckmaster, Hawker Tempest and Sea Fury, 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 was intended for the Blackburn Beverley transport aircraft. Using direct fuel injection, it achieved a remarkable 3,220 hp but was never fitted. A projected enlarged capacity version of the Centaurus was designed by Sir 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) this development was also a two-row, 18 cylinder sleeve valve engine, with the displacement increased to 4,142 cubic inches (67.9 l) (6.25x7.5), nearly as large as the American Wasp Major four-row, 28-cylinder radial, the largest displacement aviation radial engine ever placed in quantity production.

Variants

The Centaurus engine was developed in 34 different versions, starting from the 2,000 horsepower (1,490 kW) Centaurus I to the 2,405 horsepower (1,793 kW) Centaurus 663, which was designed for the Airspeed Ambassador airliner. The most potent versions that were deployed in service included the Centaurus 170, 173, 660, 661, and 662, each delivering 2,625 horsepower (1,957 kW).

Applications

Note:

Survivors

The Royal Navy Historic Flight operates a Hawker Sea Fury powered by a Bristol Centaurus.

Engines on display

Preserved Bristol Centaurus engines are on public display at the following museums:

Specifications (Centaurus VII)

Data from Lumsden

General characteristics

Components

Performance