Warner Scarab

Scarab
	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.

Variants

Scarab S-50: A 7-cyl. air-cooled radial engine introduced in 1928. With a bore and stroke of 4.25 inches and a compression ratio of 5.2:1, the Scarab developed 125 hp (93 kW) at 2,050 rpm 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) at 2,125 rpm from 301 cu in (5 L) with a dry weight of 230 lb (104 kg).

Super Scarab SS-50/50A: Increased cylinder bore to 4.625 inches to develop 145 hp (108 kW) at 2,050 rpm from 499 cu in (8 L) with a dry weight of 303 lb (137 kg).^[1]
Super Scarab SS-165: Increased compression ratio from 5.2:1 to 6.4:1 to develop 165 hp (123 kW) at 2,100 rpm with a dry weight of 341 lb (155 kg).
Super Scarab SS-185: Increased cylinder bore to 4.875 inches, developing 185 hp (138 kW) at 2175 rpm from 555 cu in (9 L), with a dry weight of 344 lb (156 kg).
R-420: Military designation of the Scarab.
R-500: Military designation of the Super Scarab 165.
R-550: Military designation of the Super Scarab 185.
145: Alternative designation for the Warner Super Scarab SS-50/50A .
165: Alternative designation for the Warner Super Scarab 165 .
185: Alternative designation for the Warner Super Scarab 185 (Primarily a helicopter application).

Applications

Among the many uses for the Scarab, the engine was fitted to the Cessna Airmaster and the Fairchild 24 (UC-61 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 UC-61s 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

Specifications (Scarab 50)

Warner Scarab engine advertisement for 1928 in Aero Digest

Data from FAA Type Certificate Data Sheet (TCDS).,^[2] Jane's all the World's Aircraft 1938^[3]

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: 29 in (740 mm)
Diameter: 36.5625 in (928.69 mm)
Height: 36.5 in (930 mm)
Dry weight: 292 lb (132 kg)

Components

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

Performance

Power output: 125 hp (93 kW) at 2,050 rpm
Compression ratio: 5.15:1
Specific fuel consumption: 0.55 lb/(hp hr) [0.334 kg/(kW hr)]
Oil consumption: 0.025 lb/(hp hr) [0.015 kg/(kW hr)]
Power-to-weight ratio: 0.43 hp/lb

References

^ Warner Engine Company. "Engine Specifications" (PDF). warnerenginecompany.com. Archived (PDF) from the original on 2022-05-20.
^ TYPE CERTIFICATE DATA SHEET NO. E-2 (PDF). DEPARTMENT OF TRANSPORTATION FEDERAL AVIATION ADMINISTRATION. Archived from the original (PDF) on 2022-05-12.
^ Grey, C.G.; Bridgman, Leonard, eds. (1938). Jane's all the World's Aircraft 1938. London: Sampson Low, Marston & company, ltd. p. 103d.

External links

Oldengine.org - US Aero Engine data page Archived 2016-03-03 at the Wayback Machine
Transcribed manual

[1] Warner Engine Company. "Engine Specifications" (PDF). warnerenginecompany.com. Archived (PDF) from the original on 2022-05-20.

[FAAcert-2] TYPE CERTIFICATE DATA SHEET NO. E-2 (PDF). DEPARTMENT OF TRANSPORTATION FEDERAL AVIATION ADMINISTRATION. Archived from the original (PDF) on 2022-05-12.

[JAWA1938-3] Grey, C.G.; Bridgman, Leonard, eds. (1938). Jane's all the World's Aircraft 1938. London: Sampson Low, Marston & company, ltd. p. 103d.

[1]

[2]

[3]

v t e Warner Aircraft Corporation aircraft engines
Names	Junior Scarab Super Scarab
Designations	R-420 R-500 R-550

v t e United States military piston aircraft engine designation system
H (four-bank H-configuration inline)	H-1640 XH-2240 XH-2470 XH-2600 XH-3130 XH-3730 H-4070
IV (inverted-V inline)	IV-1430 IV-2040 IV-2220
L (single-bank inline)	L-330 L-365 L-375 L-390 L-410 L-440 L-510 L-825
O (opposed)	O-15 O-40 O-45 O-90 O-100 O-145 O-150 O-170 O-175 O-180 O-190 O-200 (C) O-200 (F) O-205 O-235 O-290 O-300 O-335 O-360 (C) O-360 (L) O-405 O-425 O-435 O-470 O-480 O-520 O-540 (F) O-540 (L) O-550 O-580 O-805 O-1230
R (radial)	R-250 R-265 R-270 R-370 (LB) R-370 (K) R-420 R-440 R-500 R-540 (W) R-540 (K) R-545 R-550 R-600 R-670 R-680 R-720 R-755 R-760 R-790 R-830 R-915 R-975 DR-980 R-985 R-1044 R-1300 R-1340 R-1454 R-1510 R-1535 R-1640 R-1670 R-1690 R-1750 R-1820 R-1830 R-1860 R-2000 R-2060 R-2160 R-2180 R-2600 R-2800 R-3350 R-4090 R-4360 XR-7755
V (upright-V inline)	V-720 V-1150 V-1237 V-1400 V-1440 V-1460 V-1510 V-1560 V-1570 V-1650 (P) V-1710 V-1950 V-3420
V (inverted-V inline)	V-770 V-1650 (L)
VG (inverted-V inline)	VG-1410
W (three-bank W-configuration inline)	W-2779
See also: X-1800 US military gas turbine aeroengines Piston engine configurations