Rolls-Royce Pennine

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Type X-24 air-cooled sleeve-valve piston aero-engine
Manufacturer Rolls-Royce Limited
First run 1945
Major applications Not flown
Number built 1
Developed from Rolls-Royce Exe

The Rolls-Royce Pennine was a British 46-litre air-cooled sleeve valve engine with 24 cylinders arranged in an X formation. It was an enlarged version of the 22-litre Exe; a prototype engine was built and tested, but never flew.[1] The project was terminated in 1945, being superseded by the jet engine.[2]

A 100-litre 5,000 hp X32 (twin-X16) version of the Exe/Pennine, originally known as the Exe 100, was to have become the Rolls-Royce Snowdon.[3]

Rolls-Royce air-cooled engines, intended for commercial transport aeroplane use, were named after British mountains, e.g. The Pennines and Snowdon.

Specifications (Pennine)[edit]

General characteristics

  • Type: 24-cylinder supercharged air-cooled 90 degree X layout aircraft piston engine
  • Bore: 5.4 in (137.1 mm)
  • Stroke: 5.0 in (127 mm)
  • Displacement: 2791 in³ (45.73 l)
  • Length: 106 in (2692 mm)
  • Width: 39 in (991 mm)
  • Height: 37.5 in (952 mm)
  • Dry weight: 2,850 lb (1,293 kg)



  • Power output: 2,740 hp (2,043 kW) at 3,500 rpm, +12 psi boost at sea level
  • Power-to-weight ratio: 0.96 hp/lb (1.58 kW/kg)

See also[edit]

Related development

Comparable engines

Related lists



  1. ^ Rubbra 1990, p.148.
  2. ^ Gunston 1989, p.142.
  3. ^ "Rolls-Royce and the Sleeve Valve" (PDF). New Zealand Rolls-Royce and Bentley Club (07–3): 8–15. 2007. Archived from the original (PDF) on 6 December 2010.


  • Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9
  • Rubbra, A.A. Rolls-Royce Piston Aero Engines - a designer remembers: Historical Series no 16 :Rolls Royce Heritage Trust, 1990. ISBN 1-872922-00-7