The first M-25s were produced from kits imported from the United States; the main difference between the later M-25 and the R-1820-F3 was the use of metric components. 13,888 M-25s were produced in the USSR at factories in Perm and Kazan. There were a number of sub-variants which differed from the original M-25 in that they had reduction gears, rather than direct drive. Performance was similar to the equivalent Wright engines. The M-25 was later developed into the ASh-62 and was later used as a pattern for the M-70. The M-70, a twin-row 18-cylinder engine, eventually developed into the ASh-73 which powered the Tupolev Tu-4, an unlicensed, reverse-engineered copy of the Boeing B-29 Superfortress.

• Gotha Go 244
• Kharkiv KhAI-5bis
• Tupolev I-14
• Polikarpov I-15bis
• Polikarpov I-153
• Polikarpov I-16

General characteristics

• Type: 9-cylinder, air-cooled, radial engine
• Bore: 155.5 mm (6.122 in)
• Stroke: 174.5 mm (6.870 in)
• Displacement: 29.876 L (1,823.1 cu in)
• Length: 1,100 mm (43.307 in)
• Diameter: 1,365 mm (53.740 in)
• Dry weight: 434 kg (957 lb)

Components

• Supercharger: Single speed, single stage, geared centrifugal supercharger
• Fuel system: 1 K-25 (Solex) Carburetor

Performance

• Power output: 520–600 kW (700–800 hp) depending on model
• Compression ratio: 6.4:1

Related development

• Wright R-1820 Cyclone

Related lists

• List of aircraft engines

• Gunston, Bill (1986). World Encyclopedia of Aero Engines. Wellingborough: Patrick Stephens. p. 175.
• Kotelnikov, Vladimir (2005). Russian Piston Aero Engines. Crowood Press Ltd. pp. 118–119.