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The Wright R-1820 Cyclone 9 was an American radial engine developed by Curtiss-Wright and widely used on 1930s through 1950s aircraft.

Contents 1 History 2 Variants 3 Specifications (R-1820-C9HC) 4 References 5 Related contents

The R-1820 Cyclone 9 represented a further development of the Wright P-2 engine dating back to 1925. Featuring a greater displacement and a host of improvements, the R-1820 entered production in 1931. The engine remained in production well into the 1950s.

The R-1820 was built under license by Lycoming, Pratt & Whitney Canada and also, during World War II, by the Studebaker Corporation. The Soviet Union had purchased a license for the design, designated M-25, and the Shvetsov OKB was formed to further develop the engine.

The R-1820 was at the heart of many famous aircraft including B-17 Flying Fortress and SBD Dauntless bombers, the early versions of the Polikarpov I-16 fighter (as M-25), and the Piasecki H-21 helicopter.

The R-1820 also found limited use in armored vehicles in two forms. The G-200 was a 9-cylinder gas-burning radial that developed 900 hp @ 2,300 rpm and powered the M6 Heavy Tank. The Wright RD-1820 was converted to a diesel by Caterpillar Inc. as the D-200 and produced 450 hp @ 2,000 rpm in the M4A6 Sherman.

• R-1820-1 - 575 hp (429 kW)
• R-1820-22 - 950 hp (708 kW)
• R-1820-33 - 775 hp (578 kW)
• R-1820-45 - 930 hp (694 kW)
• R-1820-53 - 1,000 hp (750 kW)
• R-1820-60 - 1,200 hp (895 kW)
• R-1820-62 - 1,350 hp (1,007 kW)
• R-1820-72W - 1,425 hp (1,063 kW)
• R-1820-86 - 1,425 hp (1,063 kW)
• R-1820-97 - 1,200 hp (895 kW), turbosupercharged (gear-driven supercharger plus a turbocharger)

General characteristics

• Type: 9-cylinder supercharged air-cooled radial engine
• Bore: 6.125 in (155.6 mm)
• Stroke: 6.875 in (174 mm)
• Displacement: 1,823 in³ (29.88 L)
• Length: 47.29 in (1,200 mm)
• Diameter: 55.12 in (1,400 mm)
• Dry weight: 1,333 lb (605 kg)

Components

• Valvetrain: Two pushrod-actuated valves per cylinder with sodium-cooled exhaust valve
• Supercharger: Single-stage two-speed centrifugal type supercharger, blower ratio 7.134:1 at low speed and 10.04:1 at high speed
• Fuel system: Stromberg PD12K10 downdraft carburetor with automatic mixture control
• Oil system: Dry sump with one pressure and one scavenging pump
• Cooling system: Air-cooled

Performance

• Power output:
  
  • 1,300 hp (970 kW) at 2,600 rpm at 4,000 ft (1,220 m) military power
  • 1,000 hp (745 kW) at 2,600 rpm at 17,500 ft (5,330 m) military power
• Specific power: 0.71 hp/in³ (32.5 kW/L)
• Compression ratio: 6.55:1
• Power-to-weight ratio: 0.98 hp/lb (1.60 kW/kg)

• Bridgman, L, (ed.) (1998) Jane's fighting aircraft of World War II. Crescent. ISBN 0-517-67964-7
• Aircraft Engines in Armored Vehicles. Retrieved on October 3, 2006.

Related developments

• Wright Cyclone family
• Wright R-1300 Cyclone 7
• Wright R-2600 Cyclone 14
• Wright R-3350 Cyclone 18 (Duplex Cyclone)
• Shvetsov M-25

Comparable engines

• Pratt & Whitney R-1830 Wasp