The Alvis Leonides Major was a British air-cooled 14-cylinder radial aero engine developed by Alvis from the earlier nine-cylinder Leonides.
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 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.
Bristol Type 173 Mk1,2 & Mk3 – 2x 755/1 Mk 155, 780 hp, 755/2 Mk 160, 780 hp or 2x 850 hpHandley Page Herald – four 870 hp on PrototypeHandley Page H.P.R.1 Marathon – fourWestland Whirlwind 1 x 755/1 Mk 155, 780 hpData from Jane's All the World's Aircraft 1956-57 pp.417-9
Type: 14-cylinder twin-row air-cooled radial piston engine, geared down and superchargedBore: 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 disksSupercharger: Single speed single stage diven at 6.5:1Fuel system: Fuel injection, low pressure via Hobson or SU pumpFuel type: 100/130 octaneOil system: Dry sump, pressure and scavenge pumpsCooling system: Air-cooledReduction gear: Farman type epicyclic, ratio 0.533:12 spark plugs per cylinder, twin BTH C.14.C/1 magnetosPower output: (international rating) 860 hp (642 kW) at 1,500 ft (457 m)Compression ratio: 6.8:1Fuel 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)
