Usually one or two prototypes are built before a tank goes into production with only a few changes. However, there are exceptions. With IS series of tanks there were three of them, two of which were radically different from the final model. The similarly revolutionary T-44 evolved in a similar way. Even without significant changes in requirements,, this tank went through a series of evolutionary steps. The second variant of this vehicle was created as a result of trials held in February-March 1944. One of the main differences of the intermediate prototype was the armour. Trials showed that it was not enough to protect from the 88 mm Pak 43 L/71.
An expectation half met
Unlike the unlucky T-43, the T-44 caught the eye of senior officials from the very start. Stalin knew about this tank by late December of 1943 and inquired about the state of affairs of its development with stunning regularity. In addition, Stalin raised the question of mass production in early February of 1944. By that time the first two prototypes were only undergoing factory trials. Stalin asked about this again on February 13th and proposed that the work be expedited.
As any revolutionary vehicle, the T-44 had its advantages as well as drawbacks. There were defects linked with the driver's cabin, heating up of the left side due to the design of the exhaust system, and others. More issues were discovered when the second prototype was tested at the NIBT proving grounds in Kubinka. The T-44 had many good qualities, but the commission also indicated many defects. Their conclusion was that the issues should be corrected and a new tank built within a month. People's Commissar of Tank Production V.A. Malyshev supported this conclusion and gave the order to build two T-44 tanks with the defects corrected on March 23rd. The diameter of the tanks' road wheels was also increased to 830 mm (same as a T-34).