Armstrong Siddeley Cheetah Piston Aero Engine


Photo Courtesy of Ken Jackson

Photo Courtesy of Ken Jackson

7 cylinder radial piston aero engine

History of Type

A simple, low stressed, robust, and reliable British designed radial (the cylinders radiate from a central crankcase) aero engine.  It has 7 cylinders of some ~834 cu in (~13.6 L) and was first built in 1935 by Armstrong Siddeley Motors Ltd for Royal Air Force (RAF) training aircraft.

Early variants of the engine were known as Lynx Major.

The Cheetah was so reliable it was the first aero engine rated by the RAF to run up to 1,200 hours of usage between major overhauls.

Used in RAF training aircraft like the Avro 626 (which looks like a Tiger Moth but with a radial Cheetah engine), the twin engine navigation trainer Airspeed Oxford, and the twin engine bomber/navigation trainer and general liaison aircraft the Avro Anson.

History of HARS Engine

Our engine is serial #AS 4521 and is most likely from a RAAF Avro Anson.

Technical Specifications

Engine Type: 7 cylinder, radial piston engine, 834 cu in (~13.6 L), air cooled, supercharged, ~340 bhp at ~2,400 rpm

Manufactured: ~37,000 built in the period 1935-1948.

Usage: Fitted to many aircraft types, including:

  • Airspeed Oxford
  • Airspeed – various other models
  • Avro Anson
  • Avro 626 and 652
  • Bristol Bulldog
  • De Havilland Hawk Moth
  • Various others