Obiekt 172-2M (pre-series T-72) / T-72 Production
Development work on the new tank, designated the Obiekt 172 Ural, began in December 1967. The name "Ural" was chosen by the Vagonka bureau to highlight the origins of the design and to distinguish it from the rival Kharkov bureau's design.
There was clearly an intent from the outset to substantially redesign the tank along the lines of other Nizhni Tagil designs. Kartsev intended to replace the T-64's complicated suspension with the suspension developed for the Obiekt 167 (improved T-62). The Vagonka design bureau was not happy with the transmission since it had been designed for another engine. As a result, the bureau called in transmission designers from other design bureaus and ordered a new transmission design.
Zverev found out about the proposed changes and ordered Kartsev to Moscow on 15 January 1968 for a thorough dressing down. Kartsev agreed to limit the proposed changes to the T-64 but continued to insist that the Kharkov running gear was inadequate "and would have to be replaced eventually." Zverev apparently agreed to allow the Nizhni Tagil team to develop a prototype with the minimal changes and another prototype with a full set of changes. The basic type was a largely unaltered T-64A but with a Trashutin V-45 diesel with an ejector cooling system developed at Kharkov.
The other protoypes were based on the T-64 but were fitted with the Obiekt 167 suspension, using the new RMSh track that was being developed to upgrade the T-55 and T-62. These vehicles also had the Vagonka autoloader, and a V-45 with a Vagonka fan cooling system similar to those employed in the T-62. Ironically, at the end of 1967, Kartsev was offered the position of head of the Kharkov tank design bureau to replace the retiring Aleksandr Morozov. After the competition of the preceding decade, he decided against it, and instead recommended his fellow academy student Nikolai Shomin. Instead, he was assigned as deputy chairman of the tank research committee of the GBTU in Moscow. His position as head of the Vagonka design bureau was taken by V.N. Venediktov. Venediktov is usually given credit as the chief designer of the T-72, even though it was Kartsev who saw it through most of its gestation.
Competitive trials of the Obiekt 172 prototypes began in 1968 including tests at the Kubinka proving ground. Desert trials in Central Asia were conducted in the late summer of 1969 on two Obiekt 172 prototypes. The vehicles with the more elaborate improvements demonstrated the best results in the trials. However, the new features added 4 tons of weight to the tank, leading to the decision to employ a more powerful engine. Once again, the chosen solution was a V-2 variant, the V-46 780 horsepower engine, evolved from the V-45. The trials resulted in the decision to replace the drive train which had proven unreliable.
Prototypes of this vehicle were first completed in November 1969 and were designated Obiekt 172-2M. In February 1971, the Obiekt 172-2M tanks were subjected to cold weather trials in the Zabaikal region of Siberia. This was the final set of trials for the tank, which was accepted for production in 1971 as the T-72.
Initial production of the Obiekt 172-2M tank began in 1972 at Nizhni Tagil. These vehicles were intended for operational trials with regular Soviet Army tank units prior to official service acceptance. They differed from subsequent production vehicles in a number of details, such as the positioning of the main L2AG Luna infrared searchlight. The early service trials of the Obiekt 172-2M regiments led to an immediate improvement program to rectify flaws in the design.
This improved vehicle was designated Obiekt 172M. The Obiekt 172M had the Luna searchlight switched to the right side of the main gun, the radio antenna was moved from in front of the commander's station to a position behind it, and additional external stowage was provided on the turret. The Obiekt 172M was accepted for Soviet Army service in 1973 and entered series production in 1974; it was called the T-72.
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