Experimentation through indigenous tank design was one path to modernization for the Soviet Army prior to the fighting of World War 2 (1939-1945). From 1930 to 1932, Bolshevik Plant No.232, under the leadership of German engineer Edward Grote (imported to help with the modernization effort), was busy with work focusing on various tank projects including the T-42 "super-heavy" tank (also known as the "TG-V"). The massive vehicle, had it been completed and saw the light of day, was to spearhead any Soviet advance on the ground - primarily through force as a "breakthrough tank". However, little became of the effort for no examples were built before concentration shifted to more practical ventures.
The design that was drawn up would have had a combat weight nearing 112 tons (short) and featured an estimated running length of about 60 feet with a beam of about 12 feet and a height possibly machine that. Engineers intended to power their monstrous creation through a pairing of diesel-fueled engines outputting a combined 2,000 horsepower (1,000x2). This would supply drive power to the multi-bogied track-and-wheel arrangement which incorporated the drive sprocket at the rear and the track idler at the front. The powerpack was to have been mated to an electric transmission system - no doubt adding complexity to the design. Inside there was to be an operating crew of no fewer than fifteen personnel.
There were various armament schemes drawn up - one featuring five independently-operating turrets, another with four, and another with three. The latter offering was the most realistic - housing a 107mm M1910/30 field gun in a primary turret over the front of the hull and this bookended by smaller turrets (to be taken from the BT-2 Fast Tank series) each housing a 45mm M1932-38 (20K) gun. Up to five 7.62mm DTM machine guns would have defended the tank (two machine guns were to be turreted). Another main gun option was the Soviet 76.2mm field gun.
The hull was given a stepped design by force so as to provide each turret with the proper traversal over the hull of the vehicle. The engine was to be housed in a rear compartment giving the tank a very long, unwieldy, and ultimately cumbersome appearance. The driver's positioned was situated well-forward in the bow to offer him the best possible view of the action ahead. All told, the tank was estimated with a maximum road speed of up to 17 miles-per-hour but this was optimistic at best - mostly likely in the 9-to-12mph range. And operational range itself would have been severely restricted with two engines needed to drive the mass of this vehicle about.
The T-42 befell the same fate handed to many super-heavy tank projects of the interwar and World War 2 period. In the end, many were highly impractical (and expensive) ventures with little tactical value - serving more as propaganda measures than anything else. World War 2 would show that mobility was a key quality in line with firepower as well as reliability. While the T-42 would have met the firepower requirement, it would have been severely restricted in its mobility and assumed poor reliability in introducing two engines to do the job of one. All this on top of the cost commitment for design, development and production of the steel beast as well as the nightmare of logistics in maintaining, repairing, and transporting the mighty tank across Russian and European roads, bridges, and by railway.