Bristol Neptune

The Bristol Neptune was a seven-cylinder air-cooled radial engine developed in 1930. It had the same size cylinders as the earlier Mercury and Titan engines, 5.75 in (146 mm) x 6.5 in (165 mm) which gave a displacement of 1,182 cu in (19.3 L) and produced a maximum of 320 horsepower (239 kW). The Neptune was effectively a seven-cylinder version of the Titan.^[1]

Neptune
The Bristol Neptune
Type	Radial aircraft engine
Manufacturer	Bristol Aeroplane Company
First run	1930
Major applications	Bristol Type 110
Developed from	Bristol Titan

Applications

• Bristol Type 110

Specifications (Neptune I)

Data from Lumsden. ^[1]

General characteristics

• Type: 7-cylinder air-cooled radial engine.
• Bore: 5.75 in (146 mm)
• Stroke: 6.5 in (165 mm)
• Displacement: 1,182 cu in (19.3 L)
• Diameter: 48.4 in (1229.3 mm)
• Dry weight: 630 lb (286 kg)
• Designer: Roy Fedden

Components

• Valvetrain: Overhead valve, Four valves per cylinder
• Fuel type: 73-77 octane petrol
• Cooling system: Air-cooled
• Reduction gear: Direct drive, left hand tractor

Performance

• Power output: 295 hp (220 kW) at 1,700 rpm (rated power), 320 hp (239 kW) at 1,870 rpm at sea level
• Compression ratio: 5:1
• Power-to-weight ratio: 0.5 hp/lb (0.83 kW/kg)

See also

Related development

• Bristol Mercury
• Bristol Titan

Comparable engines

• Armstrong Siddeley Cheetah
• Armstrong Siddeley Lynx
• Avia Rk.17
• Gnome-Rhône 7K
• Jacobs R-915
• Piaggio Stella P.VII

Related lists

• List of aircraft engines

References

Notes

1. Lumsden 2003, p.103.

Bibliography

• Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6.