Armstrong Siddeley Cheetah

The Armstrong Siddeley company was formed in 1919 and was a British manufacturer of luxury cars and later, aircraft engines. In 1935 J D Siddeley was bought out by the Hawker Aircraft Company to form Hawker Siddeley and in 1960 the aircraft engine division was merged with Bristol Aero Engines to form Bristol Siddeley, which was taken over by Rolls Royce in 1966.

Armstrong Siddeley had produced a successful range of low and mid power radial engines prior to World War II including the 5 cylinder Genet in 88 and 110HP versions, the 5 cylinder 165HP Mongoose, the 7 cylinder 235HP Lynx and Cheetah Engines, and the double row Leopard, Jaguar and Panther.

While all of the Armstrong Siddeley radial engines were named after big cats, their post war jet engines were named after snakes and included the Viper engine developed for the GAF Jindervik, and the Double Mamba turboprop engine used in the Fairey Gannet anti submarine aircraft.

The Armstrong Siddeley Cheetah is a mid range, 7-cylinder, air cooled 295 horsepower radial engine, and is a pre-war and wartime product of the British Armstrong Siddeley company.

The Cheetah engine was designed by Armstrong Siddeley in 1930 and had evolved from the 7 cylinder Lynx radial of 1920 originally being known as the Lynx Major.  

It was used primarily on prewar British military aircraft, including the Avro 626 biplane trainer and most significantly the Avro Anson monoplane bomber which in 1935 was Britains first twin engined aircraft with retractable undercarriage, achieving a production run of over 10,000 airframes in England and Canada.

The Cheetah engine was the first engine to be certified for a minium of 1200 hours between overhauls. Later models built during WW2 were supercharged and fitted to the Avro Anson and Airspeed Oxford twin engined trainers.
 
The Cheetah engine saw extensive service in Australia in 48 prewar Anson GR1 reconnaissance bomber aircraft delivered in 1936, and later over 971 wartime Avro Anson's mark 1 (Cheetah IX) and 391 Airspeed Oxford twin engined trainers (Cheetah X) during WW2 imported for the Empire Air Training Scheme (EATS) program in Australia, and in total over 35,000 Cheetahs were produced.

Interesting post war use of the Cheetah engine was in the Bennet P-11 AirTruck agricultural prototype in New Zealand, the Percival Provest prototype and the Percival EP-9 Cropduster in the UK.

The Museum's Cheetah is a mark IX as fitted to the many Avro Ansons that saw service with the RAAF during WW2 and many flew as post war feeder liners and transport aircraft. 

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TECHNICAL DATA


Cylinders

Bore x Stroke

Swept Volume

Maximum Power

Weight

Carburettor Fuel System

7 cylinder air-cooled radial poppet valve direct drive engine

5.3 x 5 inches                           (133 x 127 mm)

834 cubic inches                     (13.7 litres)

355 HP     @ 2,425 rpm

556 lbs                                       (253 Kg)

With Centrifugal Supercharger