Armstrong Siddeley Deerhound

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The Armstrong Siddeley Deerhound is an aircraft engine that the British manufacturer Armstrong Siddeley developed from 1935 to 1941. The three-row 21-cylinder radial engine had a displacement of 37,031 cm³. Eleven prototypes were created. A variant with a larger displacement was called the Boarhound and was never tested in flight. A related, much larger engine was the Wolfhound , although not even a prototype was built. Development of all of these engines was halted when the plant was bombed in April 1941. On October 3, 1941, the entire project was shelved by the Air Ministry .

construction and development

In the Deerhound, it is remarkable that the three cylinder stars were not offset from one another, so that there were seven cylinder banks with three cylinders each (in-line star engine ). Unlike previous engines from the manufacturer, this in-line star engine had overhead camshafts , with each camshaft serving the intake and exhaust valves of a cylinder bank.

Flight testing began in 1938 with an Armstrong Whitworth Whitley Mark II with serial number K7243 , with problems with the cooling of the rear cylinder star. This problem was countered by the construction of "reverse flow cooling", in which a large air inlet in the rear part of the cowling directed the air flow to the front, where it exited behind the propeller . The project was set back when the Whitley crashed while taking off in March 1940, killing the pilot. Incorrect trim was found to be the cause of the accident ; the engine had nothing to do with it. A single prototype Deerhound Mark III was built and tested. It survived until the 1970s and was then scrapped. Development work on the early engines was stopped on April 23, 1941 at the behest of the Air Ministry, although the Mark III was allowed to be tested until October 3, 1941. Then all the documents had to be handed over to Rolls-Royce .

A planned variant with increased displacement, the Boarhound, was never tested and an even larger variant, the Wolfhound, only existed on drawings. The latter had four stars with seven cylinders each and a displacement of 61,172 cm³. The take-off power was estimated at 2600 to 2800 bhp (1911-2059 kW).

Armstrong Siddeley in-line radial engines

The "Hyena" construction principle (in-line radial engine) was continued with other engines, but with little economic success. Only the Deerhound and the Hyena were ever actually built.

Hyena
15 cylinders (3 stars)
terrier
14 cylinders (2 stars)
Deerhound
21 cylinders (3 stars)
Wolfhound
28 cylinders (4 stars)
Boarhound
24 cylinders (4 stars, same format as the later Junkers Jumo 222 )
Mastiff
36 cylinders (4 stars)

variants

Deerhound I
1115 bhp (831 kW): 4 pieces
Deerhound II
1500 bhp (1118 kW), displacement increased to 41,115 cm³: 6 pieces
Deerhound III
1800 bhp (1342 kW), major revision by Stewart Tresilian : 1 piece

Aircraft with Armstrong Siddeley Deerhound

The only aircraft with such an engine was the modified Armstrong Whitworth Whitley which crashed in March 1940 and was used as a test vehicle.

Data (Deerhound I)

General

  • Three-row 21-cylinder radial engine, each with three cylinders in line, air-cooled, with compressor
  • Bore: 135 mm
  • Stroke: 127 mm
  • Displacement: 37,031 cm³

Components

power

  • Power: 1115 bhp (831 kW) at 1500 rpm.
  • Output per liter: 22.44 kW / l

Individual evidence

  1. ^ A b Bill Gunston: World Encyclopedia of Aero Engines. Patrick Stephens, Cambridge 1989, ISBN 1-85260-163-9 , p. 18.
  2. ↑ a b c d Alec Lumsden: British Piston Engines and their Aircraft. Airlife Publishing, Marlborough, Wiltshire 2003, ISBN 1-85310-294-6 , p. 77.

literature

  • Alec Lumsden: British Piston Engines and their Aircraft. Airlife Publishing, Marlborough, Wiltshire 2003, ISBN 1-85310-294-6 .
  • Bill Gunston: Development of Piston Aero Engines. Patrick Stephens, Cambridge 2006, ISBN 0-7509-4478-1 .

Web links