Within the First Five Year Plan (1929-1934) the Red Army had idenrified the need for self-propelled artillery guns to support tank and infantry forces. The self-propelled weapons were known by the designation SU (Samakhodnaya Ustanovka). Initial designs, such as the SU-2, mounted a 76.2mm (3in) gun on the chassis of a Kommunar tractor, while a number of T-27 tankettes were equipped with a 37mm (1.46 in) gun for use in an antitank role.
Despite considerable interest and effort, the Red Army did not possess an effective assault/antitank self-propelled vehicle on the outbreak of war with Germany in June 1941. Adoption of the self propelled weapons had been hampered by the in creasingly excessive size and complexity of designs (the SU-7 was over 102.6 tonnes / 106 tons with a 203mm/8 in howitzer) that raised serious doubts about their utility in combat and suitability for mass production. The manufacture of more realistic designs based on proven models like the T-26 was not undertaken on a large scale because of the Red Army High Command's preference for concentrating resources on tank construction. Experimental work did continue with SU models in the initial phase of the Great Patriotic War, but the pressing need to replace the huge losses in tanks and to re-locate industry meant that production of SU vehicles had to be forgone in 1941 and for much of 1942.
By late 1942 the demands of Red Army tank, mechanized and cavalry forces or armoured vehicles were being satisfied by a revitalized industrial base. In light of this, on 23 October 1942 the Chief Defence Commissariat decided that there was now sufficient industrial capacity to order the design and production of self-propelled gun. The decision was spurred on by three other factors.
First, the success of the German StuG III assault gun had demonstrated the utility of self-propelled guns. Secondly, Soviet rifle and armoured formations reported an urgent tactical requirement for greater and more mobile direct artillery and antitank support than was currently provided by towed weapons. Third, the absence of a turret and its complex working parts meant they were cheaper and quicker to produce. This advantage was increased by the Chief Defence Commissariat emphasizing that designers use existing tank components as much as possible. Consequently, the chassis of the T-70 was used as the basis for the light SU-76 series, while medium and heavy self-propelled weapons used the T-34 and KV chassis respectively.
In April 1942 the Central Artillery Direcrorate (GAU) instructed several teams to begin work on a medium mechanized self-propelled vehicle capable of mounting the powerful 122mm (4.8 in) gun. The work of the Uralsky Heavy Machine Tool Factory (UZTM) and Zavod Nr 592 was overseen by a special team from the Conllnissariat for Tank Production (NKTP).
UZTM based its U-35 (subsequently known as the SU-122) vehicle on the chassis and hull of the T-34, placing the M-30 12mm (0.47 in) gun in a fully armoured casemate with 45mm (1.77 in) frontal armour. The increased size of the crew compartment, in comparison to a turreted vehicle, allowed a crew of five (commander, gunner, driver, and two loaders) to operate the large gun with relative ease. To increase production and also to keep costs low, the engine and transmission of the T-34 were retained.
With an overall weight just over 30.5 tonnes (30 tons), the SU-122 had a road speed of 55km/h (34 mph) and with added fuel tanks, a range of 300km (186 miles), making it more than capable of keeping up with rapidly advancing Soviet tank forces. Production of the SU-122 began in late December 1942 after receiving approval from GKO.
Although the SU-122 was capable of engaging enemy armour, the heavy tank weight of its shell reduced the muzzle velocity, making it a poor antitank weapon. Attempts to improve its firepower with the BP-460A HEAT (High Explosive Anti-Tank) round proved less successful chan hoped and, like most Soviet self-propelled gun, its primary role was direct fire support of infantry against enemy strongpoints. Even so, at short range the SU-122, with its low profile and large gun, was capable of dealing with heavy German armour, although results could be mixed.
In August 1943 the Red Army followed up its victory at Kursk with a powerful drive on the city of Kharkov in Operation Polkovodets Rumnyantsev. Attempting to halt the Soviet thrust, the German High Command mounted a series of counterattacks against the centre and eastern flank of Soviet tank forces. The Panzergrenadier Division Crossdentschland spearheaded the eastern attack against Twenty-Seventh Army and the flank of the First Tank Army.
As the Front Commander General N. F. Vatutin threw in reserves, initially to stabilize the from and then counterattack, a vicious melee erupted. lasting from 18 to 21 August. At one point on 21 August, Tiger tanks of the Grossdentschland, 3rd Panzer Regiment were roughly handled by SU-122 guns of 3 Guards Tank Corps. One Tiger of the 10th Company suffered six hits to its turret. but none of the rounds penetrated: instead they either dented, or chipped small pieces off, the armour. One round did slice off a large chink of armour that ricocheted into the fighting compartment, killing or wounding the crew. A hit on the hull's side armour would open up weld seams, leaving the inside of the Tiger exposed and also disabling the main armament.
The SU-122 is mixed performance against enemy Soviet armoured led to an abortive attempt In 1943 to develop a tank destroyer variant, named the SU-122P, armed with a long-barrelled gun. No serious production was undertaken because the weight of the weapon proved too large for the chassis. Similar problems dogged the SU-122M and SU-122-3. One improvement on the first production batches was the adoption of a new ball mount for the gun, which improved its traverse and the vehicle's frontal protection. The advent of the more powerful SU-132 self-propelled gun, as well as the highly effective SU-100 tank destroyer in mid-1943, led to the decision in November 1943 to discontinue production of the SU-122, just 11 months after it had first begun.
SEARCH BY TAG
make the text more / less