Kirov Tank T-100
The T-100 was a twin-turreted Soviet heavy tank prototype, designed in 1938–39 as a possible replacement for the T-35. The T-100 was designed to by N. Barykov's OKMO design team at S.M. Kirov Factory No. 185 in Leningrad. It was in competition with a similar design - the SMK - but neither were adopted and instead a single turret version on the SMK was ordered as the KV-1.
The project was initiated by the Red Army's need to replace the aging five-turreted T-35 tank based on combat experience in the Spanish Civil War. One of the lessons the Red Army drew from this conflict was the need for heavy 'shell-proof' armor on medium and heavy tanks. Although the T-35 was never used in Spain, its thin armor was vulnerable to the small towed antitank guns and gun-armed tanks encountered there by Soviet T-26 and BT tanks.
The T-100 was in direct competition against the very similar SMK heavy tank, by Lt-Colonel Kotin's team at the Leningrad Kirovsky Factory. The original specification was for a five-turreted "anti-tank gun destroyer" which would resist 37mm-45mm guns at any range and 76.2 mm artillery at 1,200 m. Both design teams objected to the antiquated multi-turreted design and the requirement was reduced to two turrets before serious design work began. Both tanks had some modern features, including thick, welded armor, radios and torsion bar suspension (another feature insisted upon by the design teams).
It was ordered as a successor of the mighty five-turreted T-35, world's heaviest tank of the Interbellum. The SMK (Sergey Mironovich Kirov, after a prominent Bolshevik leader assassinated in 1934) was to meet the requirements that were put forth by the Directorate of Armed Forces (ABTU) in November 1937. These requirements called for a tank that could withstand shots from a 76.2mm gun from 3,937 ft (1,200 m). It was also to be powered by a diesel engine as it was felt gasoline was too dangerous in case of hit. The requirements also called for a tank with five turrets. In 1938 the SMK was designed by Colonel Zh. Kotin (chief engineer of the Kirov Works in Leningrad) to replace the T-35. The initial study featured three turrets - the main one with a 76.2mm gun and two smaller offset ones with 45mm:
But this design was soon revised and the final layout had a 76.2 mm gun in the main turret and a 45mm in the lower turret, centerlined. This layout was virtually the same as it's competitors, T-100. The engine was based on a German BMW aircraft engine.
On May 4, 1938 the designs for the SMK and T-100 were presented to a joint committee from the Politburo and Defense Council. Both were approved to build prototypes.
The SMK prototype was completed in August 1939. It was sent to the Kubinka testing grounds outside of Moscow. The SMK was tested alongside the T-100 and KV-1 prototypes.
The T-100 tank sported two turrets placed on a long chassis. The front turret, mounting a 45mm antitank gun, was placed at a lower elevation than the other, and as such had a limited area of fire. The top turret, mounting a 76.2mm gun, was able to turn a full 360 degrees. The multi-turret design concept had been common in the 1920s, with the British one-off Vickers A1E1 Independent influencing the Soviet T-35.
The prototype T-100 tank was briefly tested alongside the other designs in the Soviet invasion of Finland in 1939 without success. It was never put into production, due to the archaic design concept, poor mobility and the availability of a far superior alternative, the KV series.The SMK was used in the Winter War with Finland. The T-100, SMK, and KV-1 prototypes were a part of the 91st Tank Battalion of the 20th Heavy Tank Brigade and had their first combat near Summa from December 17 to 19.5
In an attempt to rush a tank armed with a large howitzer capable of dealing with Finnish bunkers into use, one of the T-100s was converted into the SU-100Y self-propelled gun. It did not go into production, although the prototype was used in the defence of Moscow in 1941.
On December 19 the SMK and T-100 were joined by five T-28s and Red Army infantry. The SMK was immobilized by a mine which blew off one if its tracks. It was then found that during the repairs, under fire from the Finns, that the engine wouldn't restart. The T-100 was hooked up to it to try and tow it out of fire. But this was difficult in the icy conditions.
The SMK was eventually abandoned when the covering forces started to run low on ammunition. The SMK wasn't recovered until February 1940 when the Red Army broke through the Mannerheim Line.
There were attempts to use the T-100 chassis as a platform for an 6in howitzer carriage (T-100Z) and for self-propelled guns (here's one of several designs, the SU-100Y, armed with a 130mm naval gun).