R-1820 Cyclone
Curtiss-Wright R-1820 Cyclone Radial Engine
Type	Radial engine
National origin	United States
Manufacturer	Wright Aeronautical
First run	1930s
Major applications	Boeing B-17 Flying Fortress Curtiss P-36 Hawk Douglas B-18 Bolo Douglas DC-3 Douglas SBD Dauntless General Motors FM-2 Wildcat Sikorsky H-34 North American T-28 Trojan
Number built	47,475[1]
Variants	Shvetsov M-25
Developed into	Wright R-2600 Wright R-3350

The Wright R-1820 Cyclone 9 is an American radial engine developed by Curtiss-Wright, widely used on aircraft in the 1930s through 1950s. It was produced under license in France as the Hispano-Suiza 9V or Hispano-Wright 9V, and in the Soviet Union as the Shvetsov M-25.

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, and the Shvetsov OKB was formed to metricate the American specification powerplant for Soviet government-factory production as the M-25, with the R-1820's general design features used by the Shvetsov design bureau for many of their future radials for the Soviet air forces through the 1940s and onwards. In Spain the R-1820 was license-built as the Hispano-Suiza 9V or Hispano-Wright 9V.^[2]

The R-1820 was at the heart of many famous aircraft including early Douglas airliners (the prototype DC-1, the DC-2, the first civil versions of the DC-3, and the limited-production DC-5), every wartime example of the Boeing B-17 Flying Fortress and Douglas SBD Dauntless bombers, the early versions of the Polikarpov I-16 fighter (as the M-25), and the Piasecki H-21 helicopter.

The R-1820 also found limited use in armoured vehicles. The G-200 variant developed 900 hp (670 kW) at 2,300 rpm and powered the strictly experimental M6 Heavy Tank.

The Wright R-1820 was converted to a diesel during World War II by Caterpillar Inc. as the D-200 and produced 450 hp (340 kW) at 2,000 rpm in the M4A6 Sherman.^[3]

Notes: Unit numbers ending with W indicate engine variants fitted with water-methanol emergency power boost systems.

The Hispano-Suiza 9V is a licence-built version of the R-1820.^[4]

Hispano-Suiza 9Vr

9V with reduction gear

Hispano-Suiza 9Vb

Hispano-Suiza 9Vbr

variant of the 9Vb with reduction gear^[4]

Hispano-Suiza 9Vbrs

variant of the 9Vb with reduction gear and supercharger

Hispano-Suiza 9Vbs

variant of the 9Vb with supercharger^[4]

Hispano-Suiza 9Vd

variant of the 9V^[4]

Hispano-Suiza 9V-10

429 kW (575 hp) driving fixed-pitch propeller

Hispano-Suiza 9V-11

as -10 but RH rotation

Hispano-Suiza 9V-16

480 kW (650 hp) driving variable-pitch propeller, LH rotation

Hispano-Suiza 9V-17

as -16 but RH rotation

• M4A6 tank
• M6 heavy tank

Preserved Wright R-1820 engines are on display at the following museums:

• American Airlines C.R. Smith Museum^[5]
• Fleet Air Arm Museum^{[citation needed]}
• Delta Flight Museum^{[citation needed]}
• National Air and Space Museum^{[citation needed]}
• National Museum of the U.S. Air Force^{[citation needed]}
• Wings of Freedom Aviation Museum^[6]

• 
  Wright R-1820 Cyclone 9 engine of restored Douglas DC-3 "Flagship Knoxville" at American Airlines C.R. Smith Museum
• 
  Wright R-1820 cutaway at the Museum of Aviation
• 
  Wright R-1820 at the Museum of Aviation
• 
  Wright R-1820-82 Cyclone Radial Engine at Wings of Freedom Aviation Museum, Horsham, Pennsylvania

Data from Jane's. ^[7]

• Type: Nine-cylinder single-row supercharged air-cooled radial engine
• Bore: 6.125 in (155.6 mm)
• Stroke: 6.875 in (174.6 mm)
• Displacement: 1,823 cu in (29.87 L)
• Length: 47.76 in (1,213 mm)
• Diameter: 54.25 in (1,378 mm)
• Dry weight: 1,184 lb (537 kg)

• Valvetrain: Two overhead valves per cylinder with sodium-filled exhaust valve
• Supercharger: Single-speed General Electric centrifugal type supercharger, blower ratio 7.134:1
• Fuel system: Stromberg PD12K10 downdraft carburetor with automatic mixture control
• Fuel type: 87 octane rating gasoline
• Oil system: Dry sump with one pressure and one scavenging pump
• Cooling system: Air-cooled

• Power output: 1,000 hp (746 kW) at 2,200 rpm for takeoff
• Specific power: 0.46 hp/in³ (20.88 kW/L)
• Compression ratio: 6.45:1
• Specific fuel consumption: 0.6 lb/(hp•h) (362 g/(kW•h))
• Oil consumption: 0.35-0.39 oz/(hp•h) (13-15 g/(kW•h))
• Power-to-weight ratio: 0.84 hp/lb (1.39 kW/kg)

Related development

• Wright Cyclone family
• Wright R-1300 Cyclone 7
• Wright R-2600 Cyclone 14 (Twin Cyclone)
• Wright R-3350 Cyclone 18 (Duplex Cyclone)
• Shvetsov M-25
• Shvetsov ASh-62

Comparable engines

• Alfa Romeo 128
• BMW 114
• Nakajima Hikari
• Pratt & Whitney R-1830 Twin Wasp
• Bristol Pegasus

Related lists

• List of aircraft engines

• Bridgman, L, (ed.) (1998) Jane's Fighting Aircraft of World War II. Crescent. ISBN 0-517-67964-7.
• Conners, Chris (2013). "Medium Tank M4 Sherman". American Fighting Vehicle Database. Retrieved 9 January 2014.
• Eden, Paul & Soph Moeng, The Complete Encyclopedia of World Aircraft. Amber Books Ltd. Bradley's Close, 74-77 White Lion Street, London, NI 9PF, 2002, ISBN 0-7607-3432-1.
• Gunston, Bill. World Encyclopedia of Aero Engines: From the Pioneers to the Present Day. 5th edition, Stroud, UK: Sutton, 2006.ISBN 0-7509-4479-X
• White, Graham. Allied Aircraft Piston Engines of World War II: History and Development of Frontline Aircraft Piston Engines Produced by Great Britain and the United States During World War II. Warrendale, Pennsylvania: SAE International, 1995. ISBN 1-56091-655-9
• Lage, Manual (2004). Hispano Suiza in Aeronautics. Warrendale, USA: SAE International. ISBN 0-7680-0997-9.
• "Aircraft Engines in Armored Vehicles". Archived from the original on 2006-10-07. Retrieved 2006-10-03.