During the Soviet-Finnish War of 1939-1940, the Red Army hit a powerful defensive line in Karelia, the Mannerheim Line. Soviet soldiers were greeted with an unpleasant surprise: concrete pillboxes that could onl be destroyed with large caliber artillery.
Delivering a heavy and clumsy gun to a battlefield is not an easy task. The best solution is a gun that can drive into battle by itself. Soviet commanders remembered that work on self propelled artillery has been slowly coming along since 1931. The topic was dusted off. Two factories, Kirov and #185, got to work. By Spring of 1940, experimental vehicles have been designed: SU-14-2, T-100Y (SU-100Y), and KV-2, which may be called a tank, but was more of an assault gun with a turret. The SU-100Y did not make it in time for the war, but work on bunker busters continued. When the Great Patriotic War began, the design center was moved from Leningrad to Sverdlovsk.
From three barrels to one
The basis for the SU-100Y was the T-100 heavy tank, which lost out to the KV and did not enter production. This also put a cross over the SU-100Y. All heavy SPGs had to use the KV chassis.
In November of 1941, the Chelyabinsk Kirov Factory (ChKZ) designed the KV-7 assault tank, a vehicle with an immobile casemate carrying three guns. The project was curious, but its combat usefulness was doubtful. In fall of 1942, the Red Army GAU ordered ChKZ to develop a large caliber SPG, placing the ML-20 152 mm gun in the KV-7 hull. The project was headed by Lev Sergeevich Troyanov, the most experienced Soviet designer of SPGs.
Troyanov decided to install the casemate on a KV-1S heavy tank chassis. The wooden model and project documentation were ready at the end of 1942. In early January of 1943, the project was scheduled for a demonstration to the client. By this point, it was indexed KV-14. Two projects were demonstrated. First was designed by the factory #9 design bureau chief Fedor Fedorovich Petrov. The project was more complete, but needed many modifications of the KV-7 hull and the gun. Working blueprints for Troyanov's project were only partially complete, but his project required significantly less modifications to mass produced tanks and guns.
Stopping power
On the day after the demonstration, Joseph Stalin signed an order of the State Committee of Defense to build a prototype of the new SPG by January 31st, in less than a month. Kirov factory not only managed to deal with such a harsh quota, but finish a week early.
Trials of the new SPG were conducted from February 1st to February 5th. The KV-14 drove to the proving grounds at Chebarkul. This was a difficult trial: the SPG drove through a snowed-over highway in temperatures of -42 degrees. Water got in the engine, it kept stalling. The SPG travelled the 85 km from Chelyabinsk to Chebarkul in 13 hours.
After 234 shots, no defects were discovered in the gun or mount. The gun could not achieve the requested 3-4 RPM, but the result of 2.8 RPM was also not bad. No defects were found in the engine or transmission. There were design flaws that needed work, but by February 9th, the KV-14 was adopted into the Red Army.
And so, the USSR received an SPG with no equal anywhere in the world. It had a powerful gun, the armour of a heavy tank, and what was no less important for a fighting machine, a compact size. What's most important is that the Red Army received a universal SPG, capable of dealing with any combat mission. From the end of April of 1943, the vehicle was indexed SU-152.
The Beast-Slayer's debut was at the Battle of Kursk, in which 24 vehicles of this type took part. The small numbers did not make a large impact on the flow of events, but it turned out that, of all Soviet vehicles of the time, only a shot from this SPG could guarantee the destruction of any German vehicle of the time. It was not necessary for a 152 mm shell to penetrate enemy armour. Hero of the Soviet Union Major Sankovskiy demonstrated the combat potential of the SU-152: his vehicle destroyed 10 tanks in one battle.
The SU-152's effectiveness is also highlighted by the fact that it remained in service with Soviet tank forces until 1958.
Yuri Pasholok's book "SU-152 and other SPGs on the KV chassis" was referenced when writing this article.
Original article available here.
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