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Warner Scarab
Warner Scarab

The Warner Scarab is an American seven-cylinder radial aircraft engine, that was manufactured by the Warner Aircraft Corporation of Detroit, Michigan in 1928 through to the early 1940s. In military service the engine was designated R-420.



Amongst the many uses for the Scarab, the engine was fitted to the Cessna Airmaster and the Fairchild 24 (UC61 or Argus). Notably, in 1942, it was put into use powering the Sikorsky R-4, the first helicopter to be put into production.

Many of these reliable engines soldier on today, still powering the aircraft to which they were originally mounted. The Warner 145 and 165 HP engines are the most commonly seen of the small radials for US-built pre-World War II era aircraft, in large part because of good parts availability due to the engines having been used on World War II Fairchild UC61s and Meyers OTWs.

Warner engines are also in demand as realistically sized, though far more powerful, replacement powerplants for many replica or restored World War I era airplanes which were originally fitted with rotary engines.

Specifications (Scarab 50)

Data from FAA Type Certificate Data Sheet (TCDS).,[1] Jane's all the World's Aircraft 1938[2]

  • Type: Seven-cylinder, air-cooled, radial piston engine
  • Bore: 4.25 in (108 mm)
  • Stroke: 4.25 in (108 mm)
  • Displacement: 422 cu in (6.92 l)
  • Length: 29 in (740 mm)
  • Diameter: 36.5625 in (928.69 mm)
  • Height: 36.5 in (930 mm)
  • Dry weight: 292 lb (132 kg)
  • Valvetrain: 1 inlet and 1 exhaust valve per cylinder
  • Fuel system: Stromberg NA-5SA carburetor or Holley equivalent
  • Fuel type: 67 octane Avgas
  • Oil system: Dry sump
  • Cooling system: Air-cooled

See also

Related development

Comparable engines

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