| Deerhound | |
|---|---|
| The Armstrong Siddeley Deerhound | |
| Type | Radial engine |
| National origin | United Kingdom |
| Manufacturer | Armstrong Siddeley |
| First run | 1935 |
| Major applications | Armstrong Whitworth Whitley |
| Number built | 11 |
The Armstrong Siddeley Deerhound was a large aero engine developed by Armstrong Siddeley between 1935 and 1941. An increased capacity variant known as the Boarhound was never flown,[1] and a related, much larger design known as the Wolfhound existed on paper only. Development of these engines was interrupted in April 1941 when the company factory was bombed, and on 3 October 1941 the project was cancelled by the Air Ministry.
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The Deerhound I was a triple-row, 21-cylinder, air-cooled radial engine design. Unlike earlier Armstrong Siddeley engines the Deerhound featured overhead camshafts to operate its poppet valves, using one camshaft for each row of three cylinders.[2]
Flight testing began in 1938 using an Armstrong Whitworth Whitley II, serial number K7243, during which cooling problems were encountered. This problem was solved by engineering a 'reversed-flow' cooling system with a large air duct at the rear of the cowling taking in air and directing it forward to exit behind the propeller.[2] The project suffered a severe setback when the Whitley crashed on takeoff in March 1940, fatally injuring its crew. The accident was attributed to an incorrect elevator trim setting and was not related to the engines.[2] A single prototype Deerhound III was built and ran, and survived until the late-1970s before being scrapped. Development work on the early engines was cancelled by the Air Ministry on 23 April 1941 with running of the Mk III being allowed to continue until 3 October 1941, at which point all records were ordered to be handed over to Rolls-Royce.
A projected increased capacity variant known as the Boarhound was planned but never built, and a related much larger design, the Wolfhound, existed on paper only. The latter engine featured four rows of six cylinders, would have had a displacement of around 61 litres (3,733 cu in) and a projected takeoff power rating of 2,600–2,800 horsepower (1,900–2,100 kW).
This engine's sole aircraft application was in a modified Armstrong Whitworth Whitley which was used as a testbed.
Data from Lumsden.[2]
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