was integrated into a pod suspended under the wing. The Su-17M2 was fitted with a new ASP-17S gunsight and a PBK-3-17S bombsight. The fuel system also received a nitrogen pressurizer with a 200 kg capacity increase. Starting from aircraft Nr 03909 a central fuel feed system was also introduced with the installation of the ETsN-45 fuel pump. The Su-17M2 was also capable of carrying the Kh-25 air-to-ground missile, fitted with the 24N1 laser seeker. This was first tested by retrofitted Su-7BMs and Su-17Ms, designated Su-17MKG. The Su-17M2 could carry two such missiles, one each under the wing, mounted on an APU-68U or UM rack. The missiles were guided using a Prozhektor-1 laser-designator pod. The Su-17M2 also had an unofficial nickname, s borodoy, which means "with a beard", in Russian. Su-17M2D Test-fit of the Tumansky/Khatchaturov R-29BS-300 engine (shared with some MiG-23s), with 112.7 kN (25,335 lbf) afterburning thrust, in a bulged rear fuselage. Due to lack of performance advantage and decreased range due to higher fuel consumption, it was decided to offer this engine for export versions only. This version first flew on 31 January 1975 with A. N. Isakov at the controls. The export variant was designated Su-22 (factory code S-32M2K, NATO "Fitter-F"). It was manufactured between 1977 and 1978. Su-17UM (S-52U, "Fitter-E") First two-seat trainer version, based on the Su-17M2, but with a different, deeper fuselage with its windscreen moved forward; same length as the original Su-17M. The internal fuel capacity was reduced and the port cannon deleted, but the aircraft retained full avionics and armament. The Su-17UM first flew on 15 August 1975 with V. A. Krechetov at the controls. Test flights revealed longitudinal instability at high angles of attack which was remedied by enlarging the tail fin. The export version with the R-29 engine was designated Su-22U. The Su-17UM was manufactured between 1976 and 1978, and entered service in 1976. Su-17M3 (S-52, "Fitter-H") Based on the revised airframe of the Su-17UM, but with an avionics bay and an additional fuel tank in place of the rear cockpit, increasing the internal fuel capacity to 4850 l (1,280 U.S. gal). The Doppler radar was moved internally, and the fairing was thus removed. The Su-17M3 was equipped with the "Klen-P" laser rangefinder/target designator. A launch rail for Vympel K-13 or Molniya R-60 air-to-air missiles was added between the two existing pylons on each wing. The Su-17M3 first flew on 30