Napier Javelin

Javelin
Type	Piston aero-engine
Manufacturer	Napier & Son
First run	1932
Major applications	Martin-Baker M.B.1 (one aircraft only) Percival Mew Gull

The Napier Javelin was a British six-cylinder inline air-cooled engine designed by Frank Halford and built by Napier & Son.^[1] First flown in March 1934 in the prototype of the Percival Mew Gull racing aircraft, the engine was also used in the Spartan Arrow biplane and the Percival Gull.^[2]

Design

The six cylinders were arranged inverted and inline. Unlike the similar de Havilland Gipsy Six the poppet valves were operated by a single gear driven overhead camshaft.

Variants

Javelin I

Initial version producing 150 hp.

Javelin III

A longer stroke and increased capacity version of 160 hp.

Javelin IIIA

A Mark III with a starter motor, generator and other improvements for the Martin Baker MB.1.

Applications

• Martin-Baker M.B.1
• Percival Gull Four Mk.IIA
• Percival Mew Gull Mk.I
• Spartan Arrow

Specifications (Javelin I)

Data from ^[1]

General characteristics

• Type: 6-cylinder inverted inline air-cooled engine.
• Bore: 4.5 in (114.3 mm)
• Stroke: 5.25 in (133.35 mm)
• Displacement: 501 cu in (8.21 L)
• Length: 58.5 in (1486 mm)
• Width: 26 in (660.4 mm)
• Height: 31.5 in (800 mm)
• Dry weight: 410 lb (186 kg)

Components

• Valvetrain: Overhead cam poppet-valves
• Fuel system: Twin updraught carburettors
• Fuel type: Petrol
• Cooling system: Air-cooled
• Reduction gear: Direct drive, left hand tractor

Performance

• Power output: 150 hp (112 kW) at 2,000 rpm
• Compression ratio: 5.3:1
• Power-to-weight ratio: 0.365 hp/lb

See also

Comparable engines

• de Havilland Gipsy Six
• de Havilland Gipsy Queen
• Menasco B6/B6S
• Ranger L-440
  

Related lists

• List of aircraft engines
  

References

Notes

1. ^ ^{a b} Lumsden 2003, p.173.
2. ^ Lumsden 2003, p.174.

Bibliography

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