Alvis Leonides Major

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Leonides Major
Alvis Leonides Major.JPG
Type Radial engine
National origin United Kingdom
Manufacturer Alvis
Major applications Westland Whirlwind
Developed from Alvis Leonides

The Alvis Leonides Major was a British air-cooled 14-cylinder radial aero engine developed by Alvis from the earlier nine-cylinder Leonides.[1]

Design and development[edit]

In 1951 Alvis started development of a 14-cylinder, two row radial of 1,118 cu in (18.3 L) displacement, based on the Leonides. Certification covered the Mk. 702/1 for aeroplanes at 875 hp and the 751/1 for helicopters at 850 hp. The only numerous model of the Major was the Mk. 755/1, a medium supercharged, de-rated, obliquely mounted direct-drive and fan cooled engine fitted to the Westland Whirlwind Mks. 5, 6, 7 and 8.[2]


Specifications (Leonides Major, geared, fixed wing version)[edit]

Data from Jane's All the World's Aircraft 1956-57 pp.417-9

General characteristics

  • Type: 14-cylinder twin-row air-cooled radial piston engine, geared down and supercharged
  • Bore: 4.80 in (122 mm)
  • Stroke: 4.41 in (112 mm)
  • Displacement: 1,118 cu in (18.32 l)
  • Length: 70.9 in (180 cm)
  • Diameter: 38.9 in (99 cm)
  • Dry weight: 1,200 lb (540 kg) (dry)


  • Valvetrain: 2 sodium cooled valves per cylinder, driven by 2 cam disks
  • Supercharger: Single speed single stage diven at 6.5:1
  • Fuel system: Fuel injection, low pressure via Hobson or SU pump
  • Fuel type: 100/130 octane
  • Oil system: Dry sump, pressure and scavenge pumps
  • Cooling system: Air-cooled
  • Reduction gear: Farman type epicyclic, ratio 0.533:1
  • 2 spark plugs per cylinder, twin BTH C.14.C/1 magnetos


  • Power output: (international rating) 860 hp (642 kW) at 1,500 ft (457 m)
  • Compression ratio: 6.8:1
  • Fuel consumption: 60 imp gal (72 US gal; 270 l) per hour (at maximum continuous power)
  • Oil consumption: 6-12 pint/h (3.4-6.8 L/h)

See also[edit]

Related development
Comparable engines
Related lists


  1. ^ Gunston 1989, p.13.
  2. ^ Lumsden 2003, pp.60-61.
  • Bridgman, Leonard. Jane's All the World's Aircraft 1956-57. Jane's All the World's Aircraft Publishing Co. Ltd, London, 1956.
  • Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9.
  • Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6.

External links[edit]