March 29th, 1945, was an important date for Soviet tank building. The IS-3 tank, the result of a deep modernization of the IS-2 launched in April of 1944, was accepted into service on that day. The IS-3 had a complex fate. The army did not initially want to mass produce it, although the decision to do so later proved correct. The IS-3 was the last Soviet tank to be accepted into service during the Great Patriotic War. It did not reach the battlefield, but it worked flawlessly on the ideological front. The appearance of IS-3 tanks at the Victory Parade in Berlin was a true shock for the Western Allies, and this tank remained the gold standard for a modern fighting vehicle for seven years.
Two in one
The drama around the development of a modernization for the IS-2 tank rivals a soap opera. Initially the factory #100 design bureau was working on this project, but it was abandoned halfway through and the bureau began working on its own tank, the IS-6. The Chelyabinsk Kirov Factory SKB design bureau decided to work on their own modernization and even built a prototype. Nevertheless, the work started from scratch in the fall of 1944. The project was initially called "experimental prototype 701-A" and later "Kirovets-1". The lead designer on this project was N.L. Dukhov with M.F. Balzhi as the lead engineer. The project was meant as an intermediate step between the IS-2 and Object 701. The tank would use IS-2 components but receive radically improved protection designed using the experience of the Object 701, hence the index "701-A".
|NKTP order #729ss issued on December 16th, 1944. This was the starting point for the development of an improved Kirovets-1.
|Cutaway drawing of the improved Kirovets-1. Only the first prototypes looked like this, the final production tanks were different.
|The second improved prototype of the Kirovets-1 at the NIBT Proving Grounds, March 1945.
|This tank had a factory #200 hull and UZTM turret.
|The tank was lighter than the IS-2 due to a lighter hull and other changes.
|The tank's main feature, the "pike nose", was inherited from the IS-2U.
|The DShK machine gun mount can be seen from the back.
|The engine deck was reworked to offer improved protection from air attack. Trials showed that this was still not enough and it was later changed.
|Diagram of the armour of the second IS-3 prototype. The production tank was slightly different,
|The tank during trials at the NIBT Proving Grounds. One of the main issues was overheating, a defect that ChKZ fought with until the middle of the summer of 1945.
|The third IS-3 prototype. This was the tank that went through factory trials, as a result of which the tank was accepted into service.
|Vision diagram of the experimental IS-3 batch. Several changes were made as a result of its trials.
|An UZTM turret during trials. It turned out that the 70L steel was too brittle. Surface cracks found before the trials made the situation even worse.
|The hulls and turrets were tested at the NIBT Proving Grounds in April of 1945. The hulls were produced at factory #200 and UZTM.
|Result of firing the 122 mm D-25T gun at the front of the tank. As you can see, the front plate welds held.
|The hull could be penetrated at an angle of 320 and 40 degrees at a range of 900 meters or closer. The driver's compartment roof was also a weak spot.
|The upper side of a factory #200 tank after it was hit with an 88 mm shell. The side of the IS-3 tank was about as tough as the front of an IS-2.
|An UZTM hull after penetration trials. These photos gave rise to the myth about the bad front hull welds.
|May production IS-3 tank at the NIBT Proving Grounds. The first production IS-3 tanks looked like this.
|Mass production IS-3s were different from the prototypes from the very beginning. New changes were being introduced every month.
|Engine deck of the production IS-3 tank. It was more resilient to attack from the air.
|The IS-3 went through the biggest changes in July of 1945. 26 changes were made that month. They were introduced gradually, so the tanks changed throughout the month.
|The cooling system issues were finally resolved in July. Thanks to changing the way the external fuel tanks were mounted it was finally possible to fully rotate the turret without having to remove them.
|Spare track links were carried on the front starting in July.
|Hardpoints for a heater were introduced soon after the spare tracks were.
|The new antenna port was one of the changes introduced in September.
|The V-11 engine changed. Three hatches for changing injectors were added sometime by September of 1945, thanks to which it was no longer necessary to remove the casing every time. A similar change was introduced for the V-2.
"Preparations for producing the new IS-4 tank are going very slowly, as the factory is moving over to tractor production and the attention of factory management is focused on mastering and producing the tractors. Tanks are secondary in priority and little time is dedicated to them."
|IS-3 tanks built in 1946 on a May 1st parade in Red Square.
|The first IS-3s were issued in the summer of 1945.
|Tanks of the 2nd Guards Tank Army on parade in Berlin, September 7th, 1945. 52 of these tanks made an impression on the Western Allies.
|Recalls took place starting in 1947, primarily due to the engine bed.
|Recalls did not stop the IS-3 from remaining a constant participant in parades.