Deerhound | |
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The Armstrong Siddeley Deerhound | |
Type | inline-bankradial engine |
National origin | United Kingdom |
Manufacturer | Armstrong Siddeley |
First run | 1935 |
Major applications | Armstrong Whitworth Whitley |
Number built | 11 |
TheArmstrong Siddeley Deerhound was a largeaero engine developed byArmstrong Siddeley between 1935 and 1941. An increasedcapacity variant known as theBoarhound was never flown,[1] and a related, much larger, design known as theWolfhound existed on paper only. Development of these engines was interrupted in April 1941, when the company's factory was bombed, and on 3 October 1941 the project was cancelled by theAir Ministry.
The Deerhound I was a triple-row, 21-cylinder, air-cooledradial engine[2] design with the unusual feature of inline cylinder banks. Unlike earlier Armstrong Siddeley engines the Deerhound usedoverhead camshafts to operate itspoppet valves, using one camshaft for each bank of three cylinders.[3]
Flight testing began in 1938 using anArmstrong Whitworth Whitley II,serial numberK7243, during which cooling problems were encountered with the rear row of cylinders.[4] This problem was solved by a 'reversed-flow' cooling system, in which a large air duct at the rear of thecowling took in air and directed it forward to exit behind thepropeller.[3] The project suffered a severe setback when the Whitley crashed ontakeoff in March 1940, fatally injuring its crew.[4] The accident was attributed to an incorrectelevator trim setting and was not related to the engines.[3] 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, but running of the Mk III was allowed to continue until 3 October 1941; at this point all records were ordered to be handed over toRolls-Royce.
A projected increasedcapacity variant known as the Boarhound was planned but never built,[4] and a related much larger design, the Wolfhound, existed on paper only. The latter engine featured six banks of four cylinders, 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).[4]
The Hyena arrangement of cylinder banks arranged as a radial engine was continued with further designs, but with little commercial success. Only the Deerhound and Hyena were built.
This engine's sole aircraft application was in a modifiedArmstrong Whitworth Whitley which was used as a testbed.
Data fromLumsden.[3]
Comparable engines
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