Siddeley Puma
The Siddeley Puma was an aircraft engine made by the British manufacturer Siddeley-Deasy . The water-cooled six - cylinder in - line engine was installed in a number of different aircraft.
The engine was a further development of the Galloway Adriatic , which was not produced in large numbers due to manufacturing difficulties. In January 1917, Siddeley-Deasy began to improve this construction. The engine was initially called "Siddeley 1S", but was then named "Puma." It was an OHC engine with a camshaft driven by a vertical shaft , which actuated one inlet and two exhaust valves per cylinder ( multi-valve technology ). The exhaust valves were operated via bucket tappets , while the intake valves were operated via rocker arms . The two blocks (a cylinder bank ) with three cylinders each and the cylinder heads were cast from an aluminum alloy . The pistons ran in retracted steel liners . The large aluminum castings were also the main problem in production, as they often had unacceptable air pockets ( voids ) and could not be used as such. At times, the reject rate was 90%. Another problem was exhaust valves that burned out.
The engine had dry sump lubrication with a pressure and return pump each. For carburetion two Zenith-Hobson served updraft carburetor with devices for emaciation . The double ignition system (two spark plugs per cylinder) had two ignition distributors and ignition magnets . A mixture of 80% gasoline and 20% benzene was prescribed as fuel .
Series production began in August 1917. A total of 11,500 engines were ordered, of which 4,288 units could be delivered by December 1918. Further deliveries were canceled due to the end of the war.
In 1918 there was a modified version with higher performance, in which both the connecting rods had been strengthened and the exhaust valves had been improved. The goal of running the engine with a compression ratio of 5.4: 1 could not be achieved, so the compression was left at the original ratio of 4.95: 1.
A twelve-cylinder engine based on the Puma was the Siddeley Pacific .
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Technical specifications
- Cylinder: 6 rows
- Bore: 145 mm
- Stroke: 190 mm
- Displacement: 18,832 cm³
- Compression: 4.95: 1
- Length: 1775 mm
- Width: 610 mm
- Height: 1107 mm
- Weight: 308.5 kg
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- The Siddeley Aero Engines: The "Puma" . (PDF) In: Flight . XI, No. 14, April 3, 1919, pp. 429-431. No. 536. Retrieved February 21, 2016.Contemporary description with photos.
- (Janes) All the worlds aircraft. 9, 1919, ZDB ID 958040-2 .
- Alec SC Lumsden: British Piston Aero Engines and their Aircraft. Airlife, Shrewsbury 1994, ISBN 1-85310-294-6 .