Monday 5 June 2017

KV-3 Evolution

"To the BTU Chief, Military Engineer 1st Class, comrade Korobkov

I report that the Kirov factory made the following decisions on the KV-3:
  1. The KV-3 will be based on the Object 221 with a future plan of increasing the side armour once an 850 hp engine is received.
  2. The armament, front, and turret armour will be increased according to State plans.
  3. Since the hulls of the Objects 220 and 221 are identical in dimensions, the transmission from the 220 will be installed in the KV-3 with the V-5 engine (700 hp) with the intention to replace it with an 850 hp engine.
  4. Trials of the V-5 engine, transmission, and KV-3 suspension will be performed on the Object 220.
To achieve this, the Object 220 will be loaded to the weight of the KV-3 (70 tons), which will reduce the clearance of the tank by 22-30 mm from twisting of the torsion bars and compression of the rubber rims.

The first trial occurred on April 12th, 1941. A leak was found in the V-5 engine crankcase through the ventilation valve. In order to prevent this, the crankcase was connected to the oil tank with a hose.

The second trial occurred on April 14th. The vehicle traveled 120 km by April 15th. The results are as follows: over roads, the 700 hp engine works satisfactorily. Off-road, it is only possible to drive in second gear. Currently (in the spring) the terrain is especially difficult to traverse and the off-road performance with this engine in the summer will be better.

The issue of the gun is still unclear. The dimensions provided by factory #92 are unsatisfactory for the Kirov factory, as a stamped turret of the required height cannot be produced by the armour factories.

Senior Military Representative of GABTU, Military Engineer 2nd Class, Bubyakin."


  1. "Stamped turret"? What does that mean?

    Also, does the reference to only being able to drive off-road in second gear actually mean first or second?

    1. You take a big sheet of armour and stamp the shape out of it. Some T-34 hexagonal turrets were stamped, but they were smaller and thinner, so they were easier to make than a huge thick KV-3 turret.

      "Only in second gear" means second gear maximum, not that you can't switch into first for some reason.