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Napier Javelin

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The Napier Javelin was a British six-cylinder inline air-cooled engine designed by Frank Halford and built by D. Napier & Son. 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.

Contents

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.

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

    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

    • References

    Napier Javelin Wikipedia
    (Text) CC BY-SA