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Pelides
	Rear view of the Alvis Pelides
Type	Radial aero engine
Manufacturer	Alvis
First run	1936
Major applications	Not flown
Number built	15
Developed from	Gnome-Rhône Mistral Major

The Alvis Pelides was an unflown British air-cooled radial aero engine first developed in 1936. The Pelides Major was a projected but unbuilt development as were the Alcides, Alcides Major and the Maeonides Major, the Alvis aircraft engine range taking their names from Greek mythology.^[1]

Design and development

The Pelides was the first aero engine of Alvis design; the company had previously only built the French Gnome-Rhône Mistral Major under license.^[2] With the two companies working closely together the 14 cylinder radial layout of this engine retained metric dimensions but substituted metric screw threads with British fasteners such as BSF and Whitworth. Material specifications were different as were the detail design of internal parts such as the crankpin. The Pelides passed a 50-hour Air Ministry type test in 1937 where it produced 1,065 hp (794 kW) but no aircraft application was found and only 15 engines were built. The onset of the Second World War caused the abandonment of any further development of the Pelides and its related designs.^[3]

Variants (projected)

Pelides: 1,000 / 1,050 hp (750 / 780 kW) 2-row 14-cylinder radial, 5.75 in × 6.5 in (146 mm × 165 mm) (bore x stroke), 38.67 L (2,359.79 cu in), LH or RH, d/d, 13:19 or 0.5:1.^[4]
Pelides Major: The Pelides Major was a version retaining the same dimensions as the Pelides but with improvements to the supercharger, only built in small quantities for testing at 1,000 hp (750 kW).
Alcides: The Alcides of 1937 was a powerful supercharged 18-cylinder two-row radial engine, with a power output of 1,650 / 1,725 hp (1,230 / 1,286 kW). 2-row 18-cylinder radial, 5.75 in × 7.09 in (146 mm × 180 mm) (bore x stroke), 54.24 L (3,309.93 cu in), LH or RH, d/d, 13:19 or 0.5:1.^[4]
Alcides Major: The Alcides Major was an improved supercharged version of the Alcides.
Maeonides Major: Also designed in 1937, the supercharged Maeonides Major was effectively a smaller version of the Pelides with a power output of 680 hp (510 kW). 2-row 14-cylinder radial, 4.803 in × 4.567 in (122.0 mm × 116.0 mm) (bore x stroke), 18.98 L (1,158.23 cu in), LH or RH, 5:7.^[4]

Specifications (Pelides)

Data from Lumsden and Flight^[5]

General characteristics

Type: 14-cylinder 2 row supercharged air-cooled radial piston engine
Bore: 5.75 inch (146 mm)
Stroke: 6.5 inch (165 mm)
Displacement: 2,359.8 cu in (38.7 L)
Diameter: 52 in (1321 mm)
Dry weight: 1,190 lb (540 kg)

Components

Valvetrain: Two pushrod-actuated poppet valves per cylinder with sodium-cooled exhaust valve.
Supercharger: Single speed, single stage
Fuel system: Heated Zenith carburettor
Fuel type: Petrol, 87 Octane
Oil system: Dry sump
Cooling system: Air-cooled.

Performance

Power output: 1,000 hp (746 kW) at 2,400 rpm (rated power)
Compression ratio: 5.5:1
Power-to-weight ratio: 0.84 hp/lb (1.4 kW/kg)

References

Notes

^ Lumsden 2003, p.57.
^ Gunston 1989, p.13.
^ Lumsden 2003, p.56.
^ ^a ^b ^c Jane's All the World's Aircraft 1937. London: Sampson, Low & Martin company Limited. 1937. pp. 4d – 5d.
^ Flight -15 April 1937 Retrieved: 6 February 2009

Bibliography

Flight magazine - 15 April 1937 (Flightglobal.com)
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.