Soviet Union military aircraft designation systems

Pre-revolutionary Imperial Russia (before 1917) did not have a single national unified system but instead relied on those provided by the manufacturers of the aircraft, like Sikorsky Ilya Muromets or Anatra Anasal. == Pre-war Soviet system == The Soviet system used from shortly after the revolution in 1923 and until gradually superseded after 1940, was divided by function, with numbers assigned in order by the government.

Source: Wikipedia — Soviet Union military aircraft designation systems (CC BY-SA 4.0)