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

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

Design and development

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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 (652 kW) and the 751/1 for helicopters at 850 hp (630 kW). 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]

Variants

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Data from:British Piston Engines and their Aircraft.[3]

Leonides Major 702/1
850–875 hp (634–652 kW) for aeroplanes, also known as A.LE.M.1-1 in Air Ministry
Leonides Major 751/1
850 hp (630 kW) for helicopters, also known as A.LE.M.1-2
Leonides Major 755/1
780 hp (580 kW) for helicopters in a 35° canted mounting, also known as A.LE.M.1-6 and as Mk.155 in civil aircraft
Leonides Major 755/2
780 hp (580 kW) for helicopters in a vertical mounting, also known as A.LE.M.1-6 and as Mk.160 in civil aircraft

Applications

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Specifications (Leonides Major 702/1)

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Data from Jane's All the World's Aircraft 1956-57.[4]

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)

Components

  • Valvetrain: 2 sodium cooled valves per cylinder, driven by 2 cam discs
  • Supercharger: Single speed single stage driven 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

Performance

  • 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

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Related development

Comparable engines

Related lists

References

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  1. ^ Gunston, Bill (1989). World encyclopaedia of aero engines (Fully rev. 2nd ed.). Wellingborough: P. Stephens. p. 13. ISBN 1-85260-163-9.
  2. ^ Lumsden 2003, pp.60-61.
  3. ^ Lumsden, Alec (2003). British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing. pp. 60–61. ISBN 978-1-85310-294-3.
  4. ^ Bridgman, Leonard, ed. (1956). Jane's all the World's Aircraft 1956–57. London: Jane's all the World's Aircraft Publishing Co. Ltd. pp. 417–419.