The Armstrong Siddeley Cheetah is a seven-cylinder British air-cooled aircraft

radial engine The radial engine is a reciprocating engine, reciprocating type internal combustion engine, internal combustion engine configuration in which the cylinder (engine), cylinders "radiate" outward from a central crankcase like the spokes of a wheel. ...

of 834 cu in (13.65 L)

capacity Capacity or capacities may refer to: Mathematics, science, and engineering * Capacity of a container, closely related to the volume of the container * Capacity of a set, in Euclidean space, the total charge a set can hold while maintaining a giv ...

introduced in 1935 and produced until 1948. Early variants of the Cheetah were initially known as the Lynx Major.Lumsden 2003, p.74. The Cheetah was used to power many British

trainer aircraft A trainer is a class of aircraft designed specifically to facilitate flight training of pilots and aircrews. The use of a dedicated trainer aircraft with additional safety features—such as tandem flight controls, forgiving flight characteristic ...

during

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

including the

Avro Anson The Avro Anson is a British twin-engine, multi-role aircraft built by the aircraft manufacturer Avro. Large numbers of the type served in a variety of roles for the Royal Air Force (RAF), Fleet Air Arm (FAA), Royal Canadian Air Force (RCAF), R ...

and

Airspeed Oxford The Airspeed AS.10 Oxford is a twin-engine monoplane aircraft developed and manufactured by Airspeed Ltd, Airspeed. It saw widespread use for training Commonwealth of Nations, British Commonwealth aircrews in navigation, radio-operating, bombin ...

Design and development

The Cheetah was developed from the earlier Lynx using the increased bore cylinders from the

Armstrong Siddeley Panther The Armstrong Siddeley Panther was a 27-litre 14-cylinder twin-row air-cooled radial aero engine developed by Armstrong Siddeley. It was originally named the Jaguar Major.Lumsden 2003, p.72. Variants ;AS Panther IIIA:500 hp (370 kW) ;AS Pa ...

but the engine retained the

stroke Stroke is a medical condition in which poor cerebral circulation, blood flow to a part of the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemor ...

of the Lynx. Initially only direct-drive variants were produced with later engines being made available with propeller reduction gear of various

ratios In mathematics, a ratio () shows how many times one number contains another. For example, if there are eight oranges and six lemons in a bowl of fruit, then the ratio of oranges to lemons is eight to six (that is, 8:6, which is equivalent to th ...

Supercharger In an internal combustion engine, a supercharger compresses the intake gas, forcing more air into the engine in order to produce more power for a given displacement (engine), displacement. It is a form of forced induction that is mechanically ...

s were also available for later variants, both geared and directly driven by the

crankshaft A crankshaft is a mechanical component used in a reciprocating engine, piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating Shaft (mechanical engineering), shaft containing one or more crankpins, ...

. The basic design of the Cheetah remained unchanged from its introduction in 1935 to the last examples built in 1948. It was the first engine of its type to be certified for 1,200 hours of operational

time between overhaul Time between overhauls (abbreviated as TBO or TBOH) is the manufacturer's recommended number of running hours or calendar time before an aircraft engine or other component requires overhaul. On rotorcraft, many components have recommended or ma ...

s (TBO), with over 37,200 examples built.

Variants

''List from:'' Lumsden''Note:'' ;Lynx V (Lynx Major) :1930, 230 hp (171 kW). ;Cheetah V :1935, 270 hp (201 kW) at 2,100 rpm. ;Cheetah VA :1935, 285 hp (212 kW) at 2,425 rpm. ;Cheetah VI :1935, 307 hp (229 kW) at 2,425 rpm. ;Cheetah VIA :1936, as Mk VI but with Mk IX cylinders. Armstrong Siddeley Cheetah Mk

;Cheetah IX :1937, 345 hp (257 kW) at 2,425 rpm. ;Cheetah X :1938, 375 hp (280 kW) at 2,300 rpm. ;Cheetah XI :345 hp (257 kW) at 2,425 rpm, geared version of Cheetah X. ;Cheetah XII :Similar to Mk X, adapted for target drone aircraft. ;Cheetah XV :420 hp (313 kW) at 2,425 rpm. ;Cheetah XVII :1948, 385 hp (287 kW) at 2,425 rpm. ;Cheetah XVIII :385 hp (287 kW) at 2,425 rpm, carburettor modified for aerobatics. ;Cheetah XIX :355 hp (265 kW) at 2,425 rpm ;Cheetah 25 :345 hp (257 kW) at 2,425 rpm, Cheetah XV uprated to 475 hp (355 kW) at 2,700 rpm, modified constant-speed unit. ;Cheetah 26 :385 hp (287 kW). ;Cheetah 27 :1948, 385 hp (287 kW).

Applications

Surviving engines

As of October 2008 at least four Cheetah engines remained airworthy. Two Cheetah 17s power the Anson T21 operated by the Classic Air Force and another pair of Cheetah 17s are fitted to Avro Nineteen, ''G-AHKX'' registered to

BAE Systems BAE Systems plc is a British Multinational corporation, multinational Aerospace industry, aerospace, military technology, military and information security company, based in London. It is the largest manufacturer in Britain as of 2017. It is ...

but normally based at the

Shuttleworth Collection The Shuttleworth Collection is a working aviation, automotive and agricultural collection located at Old Warden Aerodrome in Bedfordshire, England. History The collection was founded in 1928 by aviator Richard Ormonde Shuttleworth. While ...

Engines on display

Preserved Armstrong Siddeley Cheetah engines are on public display at the following museums: *

Arkansas Air & Military Museum The Arkansas Air & Military Museum is an aviation and military museum located at Drake Field in Fayetteville, Arkansas. It is the largest aviation museum in Arkansas. History The museum was originally established in 1986 as the Arkansas Air Muse ...

Aviation Heritage Museum (Western Australia) The Aviation Heritage Museum is a museum located in Bull Creek, Perth, Western Australia. Created and maintained by the Air Force Association of Western Australia, it houses many military and civilian aircraft, aircraft replicas and aircraft en ...

Brooklands Museum Brooklands Museum is a motoring and aviation museum occupying part of the former Brooklands Motor Course in Weybridge, Surrey, England. Formally opened in 1991, the museum is operated by the independent Brooklands Museum Trust Ltd, a private l ...

City of Norwich Aviation Museum The City of Norwich Aviation Museum is a volunteer-run museum and charitable trust dedicated to the preservation of the aviation history of the county of Norfolk, England. The museum is located on the northern edge of Norwich International ...

in Horsham St Faith, Norfolk. *

Fleet Air Arm Museum The Fleet Air Arm Museum is devoted to the history of British naval aviation. It has an extensive collection of military and civilian aircraft, aero engines, models of aircraft and Royal Navy ships (especially aircraft carriers), and paintings ...

Historical Aircraft Restoration Society The Historical Aircraft Restoration Society, often referred to by its acronym, HARS, is an Australian based aircraft restoration group. The group has two museums, at Shellharbour Airport in New South Wales, Australia, and Parkes, New South Wale ...

Albion Park, New South Wales, Australia *

Malta Aviation Museum Malta Aviation Museum is an aircraft museum situated on the site of the former Royal Air Force airfield in the village of Ta'Qali, on the island of Malta. The museum, based in three hangars, covers the history of aviation on the island with exh ...

Port Elizabeth Gqeberha ( , ), formerly named Port Elizabeth, and colloquially referred to as P.E., is a major seaport and the most populous city in the Eastern Cape province of South Africa. It is the seat of the Nelson Mandela Bay Metropolitan Municipal ...

branch of the

South African Air Force Museum The South African Air Force Museum houses exhibits and restores material related to the history of the South African Air Force. The museum is divided into three locations, AFB Swartkop outside Pretoria, AFB Ysterplaat in Cape Town and at the Por ...

Royal Air Force Museum Cosford The Royal Air Force Museum Midlands, located at RAF Cosford in Shropshire, is a free museum dedicated to the history of aviation and the Royal Air Force in particular. The museum is part of the Royal Air Force Museum, a non-departmental public ...

* South Australian Aviation Museum, Adelaide. Two Mk9 Operational Displays

Specifications (Cheetah IX)

References

Notes

Bibliography

* Gunston, Bill. ''World Encyclopedia of Aero Engines''. Cambridge, England. Patrick Stephens Limited, 1989. * Lumsden, Alec. ''British Piston Engines and their Aircraft''. Marlborough, Wiltshire: Airlife Publishing, 2003. .

External links

''Flight'' magazine, 19 May 1939 - Introduction of the Cheetah X - Flightglobal.com
{{ASaeroengines 1930s aircraft piston engines Aircraft air-cooled radial piston engines

Cheetah The cheetah (''Acinonyx jubatus'') is a large Felidae, cat and the Fastest animals, fastest land animal. It has a tawny to creamy white or pale buff fur that is marked with evenly spaced, solid black spots. The head is small and rounded, wit ...