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Avia Rk.12

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Rk.12
Type Seven-cylinder air-cooled radial
National origin Czechoslovakia
Manufacturer Avia (Avia akciova spolecnost pro prumysl letecky), Prague

One of Avia's own designs, the 1930s Avia Rk.12 was a seven-cylinder radial engine with a rated output of 150 kW (200 hp), built in Czechoslovakia.

Design and development

As well as producing aircraft and building Hispano-Suiza and Lorraine aero-engines under licence, Avia also designed and built their own radial engines. Their Rk.12 was a seven-cylinder supercharged model, rated at 200 hp.[1]

It was a conventional air-cooled radial: nitrided steel barrels with integral fins were screwed into heat-treated Y alloy heads. The pistons were also of heat-treated Y alloy. The crankcase was cast from aluminium alloy, with some minor parts using magnesium alloy. The single-throw, two-piece crankshaft was linked to the pistons with an I-section Y alloy master rod, with a single-piece big end, which carried the other six piston rods.[1]

Applications

Avia 51

Specifications

Data from Jane's All the World's Aircraft 1938[1]

General characteristics

  • Type: Seven-cylinder air-cooled radial
  • Bore: 130 mm (5.12 in)
  • Stroke: 130 mm (5.12 in)
  • Displacement: 12.08 L (737 cu in)
  • Length: 1,047.5 mm (41.24 in)
  • Diameter: 1,110 mm (43.7 in
  • Dry weight: dry, with ancillaries, without propeller hub 215.5 kg (475 lb)

Components

  • Valvetrain: one inlet and one exhaust valve per cylinder, operated by push rods via rocker gear. Six cam push rod disc drive.
  • Supercharger: impeller drive ratio 10.7:1
  • Fuel system: single barrel Zenith 70P or Stromberg NAR68 carburettor
  • Ignition system: Scintilla magnetos, automatic advance
  • Fuel type: petrol, 74 Octane
  • Oil system: dry sump, with one pressure and one scavenging pump
  • Cooling system: air-cooled
  • Reduction gear: direct drive

Performance

  • Power output: rated, maintained to 3,000 m (9,840 ft), at 2,200 rpm: 150 kW (200 hp)
  • Power output: maximum continuous 195 kW (260 hp)
  • Power output: take-off 210 kW (280 hp)
  • Compression ratio: 5.3:1
  • Fuel consumption: 62 L/hr (13.64 Imp gal/h, 16.4 US gal/h)
  • Oil consumption: at cruising speed, 2 kg/h (4.4 lbs/h)

References

  1. ^ a b c Grey, C.G. (1972). Jane's All the World's Aircraft 1938. London: David & Charles. p. 31d. ISBN 0-7153-5734-4. {{cite book}}: Cite has empty unknown parameter: |coauthors= (help)
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