Russian tank researcher Yuri Pasholok has written an article chronicling the development of the Soviet T-10 heavy tank for a Russian language blog. Peter Samsonov at Archive Awareness blog has provided an English language translation of the article. It can be read here.
The Last Soviet Heavyweight
The last fighting machine named after Stalin would be the last Soviet heavy tank. It appeared at a time when the trend of constant increase in the weight of tanks came to a stop. Without the ability to grow protection and armament of tanks at the expense of weight, the designers of the IS-8 (T-10) used a number of creative solutions.
The end of an era of giants
Starting from late 1943, Soviet tank designers steadily increased the mass of their heavy tanks. Eventually, the initial stages of tank projects stepped over the psychological limit of 50 tons. The IS-3 was an exception, but it was essentially a deep modernization of the IS-2. Interestingly enough, there were doubts at the very top of the Main Armour Directorate (GBTU) about the suitability of the IS-3 for service. The Object 701, which hit a mass of 55 tons during the prototype phase, seemed much more desirable. Development of the future IS-4 was moving slowly: the first prototypes were ready for the summer of 1944, but the tank was constantly changed, and, despite being designed as an answer to the Ferdinand, only reached mass production in 1947. By that time, production of the IS-3 not only started, but also ended, netting a total of 1555 tanks.