Mikoyan-Gurevich MiG-21SPS (725) as used by the East German Air Force at the Museum Park of Aviation and Technology, Merseburg (Germany)
The Mikoyan-Gurevich MiG-21 (NATO reporting name: Fishbed) is a supersonic jet fighter aircraft, designed by the Mikoyan-Gurevich Design Bureau in the Soviet Union. It was popularly nicknamed "Balalaika", from the aircraft's planform-view resemblance to the Russian stringed musical instrument or "ołówek" (pencil) by Polish pilots due to the shape of its fuselage. Approximately 60 countries over four continents have flown the MiG-21, and it still serves many nations a half-century after its maiden flight. A total of 10.645 aircraft were built in the USSR. A total of 194 MiG-21F-13s were built under licence in Czechoslovakia, and Hindustan Aeronautics of India built 657 MiG-21FL, MiG-21M and MiG-21bis (of which 225 were bis).
The MiG-21PFM or Perekhvatchik (Interceptor) Forsirovannyy (Uprated) Modernizirovannyy (Modernised) was a modernised MiG-21PF, with an upgraded RP-21M radar, SRZO-2 Khrom-Nikkel IFF transponder and other changes in avionics. Further, later-production PFMs reintroduced cannon armament, in the form of the capability to carry a GSh-23 cannon and 200 rounds in an underbelly pod. Following tests in 1966, MiG-21PFM aircraft built after 1968 could carry the Kh-66 air-to-surface missile. This East German Air Force MiG-21 is actually a MiG-21PFM without cannon and locally designated as MiG-21SPS, or Sduv Pogranichnovo Sloya ("Boundary Layer Blowing") with a newly developed flap-blowing system.
This was done to avoid confusion with the local MiG-21PFM designation given to the modified MiG-21PF.