Alvis Leonides Major

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

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

Design and development

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

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

Bristol Type 173 Mk3 – 2x 755/1 (Mk.155) 780 hp (580 kW); 2x 755/2 (Mk.160) 780 hp (580 kW)
Handley Page HPR.5 Herald – four 850 hp (630 kW) 702/1
Westland Whirlwind 1x 755/1 (Mk.155) or 1x 755/2 (Mk.160) 780 hp (580 kW)

Specifications (Leonides Major 702/1)

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)

References

^ Gunston, Bill (1989). World encyclopaedia of aero engines (Fully rev. 2nd ed.). Wellingborough: P. Stephens. p. 13. ISBN 1-85260-163-9.
^ Lumsden 2003, pp.60-61.
^ Lumsden, Alec (2003). British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing. pp. 60–61. ISBN 978-1-85310-294-3.
^ 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.

[Gunston-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.

[Lumsden-3] Lumsden, Alec (2003). British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing. pp. 60–61. ISBN 978-1-85310-294-3.

[JAWA56-57-4] 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.

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