Pobjoy R

The Pobjoy R is a British seven-cylinder, radial, air-cooled, aircraft engine designed and built by Pobjoy Airmotors.[1] Introduced in 1926 it was a popular engine for ultralight and small aircraft in the 1930s. A notable feature of the Pobjoy R was the propeller reduction gear which allowed the small engine to operate at more desirable higher speeds.

Preserved Pobjoy R at the Shuttleworth Collection
Type Piston radial aero-engine
Manufacturer Pobjoy Airmotors
First run 1926
Major applications BA Swallow
Comper Swift


Engines on display

A preserved Pobjoy R engine is on display at the Shuttleworth Collection, Old Warden, Bedfordshire.

Two Pobjoy R engines, one installed in the remains of Comper Swift (R222 / LV-FBA) will be soon on display at the National Aviation Museum in Buenos Aires Province, Argentina.

Specifications (Pobjoy R)

Data from Lumsden.

General characteristics

  • Type: 7-cylinder air-cooled, radial, left-hand tractor
  • Bore: 3.03 in (77 mm)
  • Stroke: 3.43 in (87 mm)
  • Displacement: 173.05 cu in (2.84 L)
  • Diameter: 25.5 in (647.7 mm)
  • Dry weight: 135 lb


  • Oil system: Dry sump
  • Cooling system: Air-cooled


See also

Related development

Comparable engines

Related lists



  1. Lumsden 2003, p.178.


  • Guttery, T.E. The Shuttleworth Collection. London: Wm. Carling & Co, 1969. SBN 901319-01-5
  • Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6.
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