Shvetsov M-25

The Shvetsov M-25 was an aircraft radial engine produced in the Soviet Union (USSR) in the 1930s and 40s, a licensed production variant of the Wright R-1820-F3.

Design and development

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, a reverse-engineered copy of the Boeing B-29.

Applications

• Neman R-10
• Polikarpov I-14
• Polikarpov I-15bis
• Polikarpov I-153
• Polikarpov I-16

Specifications (Shvetsov M-25)

Family tree of Shvetsov engines

General characteristics

• Type: 9-cylinder, air-cooled, radial engine
• Bore: 6.125 in (155.6 mm)
• Stroke: 6.875 in (174 mm)
• Displacement: 1,823.1 in³ (29.876 L)
• Dry weight: 499kg (999lb)

Components

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

Performance

• Power output: 700-800hp depending on model
• Compression ratio: 6.4:1

References

• 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.