Warner Scarab

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Warner Scarab 110.jpg
Preserved Warner Scarab
Type Radial engine
Manufacturer Warner Aircraft Corporation
First run November 1927

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.


A 7-cyl. air-cooled radial engine introduced in 1928, the Scarab developed 125 hp (93 kW) at 2,050rpm from 422 cu in (7 l) with a dry weight of 285 lb (129 kg).
Scarab Junior
A 5-cyl. version introduced in 1930 developing 90 hp (67 kW).
The R-500-7 Super Scarab model 165 displayed at Museo dell'Aria e dello Spazio in San Pelagio, Due Carrare, Province of Padua.
Super Scarab 165
Increased capacity 7-cyl engine developing 165 hp (123 kW) at 2,100rpm from 499 cu in (8 l) with a dry weight of 332 lb (151 kg).
Super Scarab SS-50
Alternative company designation for the Super Scarab.
Super Scarab SS-50A
A 145 hp (108 kW) de-rated Super Scarab.
Super Scarab 185
With the capacity increased further, developing 185 hp (138 kW) - 200 hp (149 kW) from 555 cu in (9 l).
Military designation of the Scarab.
Military designation of the Super Scarab 165.
Military designation of the Super Scarab 185.
Alternative designation for the Warner Super Scarab SS-50A .
Alternative designation for the Warner Super Scarab 165 .
Alternative designation for the Warner Super Scarab 185 (Primarily a helicopter application).


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-WWII era aircraft, in large part because of good parts availability due to the engines having been used on WWII 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.

Application list[edit]

Specifications (Scarab 50)[edit]

Warner Scarab engine advertisement for 1928 in Aero Digest

Data from FAA Type Certificate Data Sheet (TCDS).[1]

General characteristics

  • 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: 14 in (35.5 cm)
  • Height: 36.5 in (93 cm)
  • Dry weight: 292 lb (132.5 kg)


  • Valvetrain: 1 inlet and 1 exhaust valve per cylinder
  • Fuel system: 2 Stromberg carburetors
  • Fuel type: 67 octane Avgas
  • Oil system: Dry sump
  • Cooling system: Air-cooled


See also[edit]

Related development
Comparable engines
Related lists


  1. ^ FAA TCDS - E-2 Retrieved: November 19, 2010.

External links[edit]