with a Tumansky R-29BS-300 engine. S-32M2D An Su-17 tested with ski landing gear, similar to that used on the S-26 (Su-7), used for [very] rough field landing and takeoff tests. Su-52U The Su-17UM/Su-22U two-seat combat-trainer version with a completely re-designed nose housing the tandem cockpits for student and instructor. S-52 In a reverse development the trainer modifications were adapted for a new Attack variant, the Su-17M3. S-52K An export variant of the S-52, given the designation Su-22M. S-52M3K Series production Su-22M3 aircraft with laser range-finder and avionics mods. S-52UK The trainer variant with all the S-32M2K structural modifications and a reduced weapons portfolio. S-52UM3 The Su-17UM3 for the VVS with avionics and aero-dynamic changes. S-52UM3K The export version of the Su-17UM3. S-52R Tactical Reconnaissance Su-17M3R with a KKR (Kombinirovanny Konteiner Razvedy – combined reconnaissance pod) on the centre-line pylon S-54 Production Su-17M4 fighter-bombers. S-54K Export Su-17M4s, designated Su-22M4. S-54R Tactical reconnaissance Su-17M4R with a KKR (Kombinirovanny Konteiner Razvedy – combined reconnaissance pod) on the centre-line pylon. Operators The People's Air and Air Defence Force of Angola operates 14 Su-22 variants. the Aerospace Force of the Islamic Revolutionary Guard Corps (IRGC-AF) operates the Iranian Su-22 fleet and not the regular military. The IRGC aircraft have military identification numbers that are prefixed '15-' Iran received 40 Su-20/22s from Iraq in 1991. While non-operational for several years, in 2013 Iran started an overhaul program. In March 2015, it seems that some of the IRGC-AF Su-22s were transferred to the Syrian Arab Air Force to fight in the ongoing Civil War. Iran currently possesses 30 operational Su-22s. In July 2018 Iranian military technical experts successfully overhauled and modernized 10 Su-22s, giving them the ability to carry smart bombs, fire precision-guided munitions, transfer data from UAVs, and in the near future the system necessary to utilize air-launched cruise missiles with a range of 1500 km will be installed on them. The Libyan Air Force operated as many as 90 Su-22 aircraft, with around 40 Su-22M3 and Su-22UM3K aircraft in service at the beginning of 2011 when the Libyan uprising started. During the Libyan Civil War, the Gaddafi regime used Su-22s in combat operations. As of 2017, two Su-22s remained in service. The Polish Air Force currently operates 12 Su-22M4 and 6 Su-22UM3K aircraft of 120 delivered. Other airframes have been preserved in warehouses. Poland operated 27 Su-20s from 1974 until the 1990s. 28 Su-22 aircraft