ASU - 85 The ASU - 85 ( , ' airborne self - propelled mount ' ) is a soviet - designed airborne self - propelled gun of the Cold War Era . From 1959 it replaced the open - topped ASU - 57 in service but was in its turn replaced by the BMD - 1 from 1969 . Development history . Development of a new assault gun for the armed forces started at the OKB - 40 design bureau of the Mytishchi Machine Building Plant ( MMZ ) , under the supervision of chief designer Nikolaj Aleksandrovich Astrov . The first Ob ' yekt 573 prototype was ready for factory tests in the second half of 1953 . This first vehicle was followed by a small batch of three improved vehicles that were evaluated by the armed forces in 1956 - 1957 . The improved vehicles were powered by a new , horizontal six cylinder diesel engine , the YaMZ - 206V , instead of the original V - 6 of the PT - 76 . In 1958 the order to start series production of the SU - 85 - as it was initially known ( although there was already a vehicle with that same name , based on the T - 34 ) - was given . However , as a result of an order from the Ministry of Defense to add an armoured roof ( the initial vehicles were still open - topped ) , series production could only begin in 1961 . By then , the configuration was already out of date and in the second half of the 1960s the VDV became the main operator of the SU - 85 and renamed it into ASU - 85 . Design . The SU - 85 / ASU - 85 is based on the PT - 76 tank chassis , but without the amphibious capabilities and fitted with a new engine . The vehicle has three compartments : the driver ' s in front , the combat compartment in the center , and the engine compartment at the rear . The armament consists of a D - 70 ( 2A15 ) 85mm gun , derived from F . F . Petrov ' s D - 48 . The L / 67 ordnance has a total weight of 1 , 865 kg and an elevation range from - 4 . 50° to + 15° . Traverse is 15° either side . The D - 70 fires the same ammunition as the D - 48 ( 3BK - 7 HEAT , BR - 372 HVAP - T and OF - 372 HE ) , the combat load is 45 rounds . The gun has an effective range of 1 , 150 m and a maximum range of 10 km . The coaxial machine gun is either the SGMT or the PKT with a combat load of 2 , 000 rounds . Both the main gun and the coaxial machine gun are aimed by means of the TShK - 2 - 79 sight . For nighttime fire , the TPN1 - 79 - 11 sight is used , in combination with the IR searchlight L - 2 . Indirect fire is conducted with the help of the S - 71 - 79 and PG - 1 sights . Furthermore , the commander is provided with observation devices TNPK - 20 ( day ) and TKN - 1T ( night ) . All ASU - 85s were provided with an R - 113 radio and the R - 120 intercom system . In the early 1970s , some vehicles were fitted with a DShK - M 12 . 7mm heavy machine gun with 600 rounds . These vehicles had a reduced combat load of 39 main gun rounds and received the NATO designator ASU - 85 M1974 . The original designation was SU - 85M or ASU - 85M . The ASU - 85 could also be equipped with smoke generators BDSh - 5 . Service history . The Soviet Airborne Forces used the ASU - 85 in airborne operations . Its primary role was light infantry support or assault , with limited anti - tank capability . Each Airborne Division had one assault gun battalion with 31 ASU - 85 . The Polish 6th Pomeranian Airborne Division ( ) had an equal number . The ASU - 85 became possible with the introduction of the Mi - 6 and Mi - 10 helicopters and high - capacity multi - chute and retro - rocket systems for fixed wing - drops . It was first observed by NATO in 1962 , and was widely used by Soviet and Polish airborne units . Variants . There are no variants of the ASU - 85 , but its chassis served as the basis for other designs such as the chassis GM - 575 of the ZSU - 23 - 4 " Shilka " and the GM - 568 and GM - 578 chassis ' of the launch vehicle 2P25 and radar vehicle 1S91 of the 2K12 " Kub " system .