KV-4 Initial Proposal

Upon learning of the German 105 mm Flak 39 and its potential conversion into a tank gun, Soviet tank engineers began development of the superheavy KV-4 tank. However, the initial requirements were a lot more reasonable than what ended up winning the design competition.

"Tactical-technical Requirements for the Design and Production of an Experimental Heavily Armoured Tank

1. Purpose of the tank:
1. Fighting enemy heavy tanks.
2. Destruction of concrete fortifications and heavy engineering structures.
3. Destruction of enemy artillery and personnel.
2. Mass: 70-72 tons.
3. Armour:
1. Front plate: 130 mm
2. Side: 125 mm
3. Turret side at an angle of no less than 30 degrees: 130 mm
4. Roof and floor: 40 mm
5. Other plates: equivalent to side armour
4. Armament:
1. One 107 mm gun:
1. Horizontal range: 360 degrees
2. Vertical elevation: 15-17 degrees
3. Vertical depression: -2 - -3 degrees
2. 3 DT machineguns, of which:
1. One is coaxial with the main gun
2. One is installed in the turret bustle
3. One is installed in the front of the hull
3. One PPSh submachinegun
4. One flamethrower
5. Ammunition:
1. Shells and propellant for the 107 mm gun: 70-80
2. Rounds for DT machineguns: 4000-4500
3. PPSh rounds: 450-500
4. Hand grenades: 25-30
6. Tank performance:
1. Maximum speed: 35 kph
2. Maximum off-road speed: 20 kph
3. Maximum grade: 37-40 degrees
4. Height of a climbable wall: 1.2 meters
5. Clearance: at least 450 mm
6. Ground pressure without submerging the track: 0.85-0.9 kg/cm^2
7. Engine:
1. 1200 hp diesel engine
   Temporarily use 850 hp diesel engines.
2. The fuel and oil reserves in the tank must allow for at least 10 hours of driving.
3. The cooling system, lubrication system, and fuel system must allow the engine to work normally for 10 hours of continuous motion in any mode of operation with external temperature range of -40 to +40 degrees.
8. Transmission and suspension:
1. The transmission must be of the planetary type, and the suspension must be of the KV type, allowing for normal operation and control of the tank. Temporarily, a mechanical transmission is allowed, but the tank must be easily controlled with the aid of servo motors.
2. The brakes of the tank must hold it on a 45 degree slope at any movement speed.
9. Tank crew:
1. The tank crew is composed of 6 men: commander, gunner, loader, mechanic in the turret (assistant loader), driver, radio operator in the hull.
2. The driver must be able to see both fenders in front of the tank with his observation devices.
3. The maximum amount of effort expended by the driver to turn the tank must be 15-20 kg, and the maximum amount of effort to depress the clutch must be no more than 25-30 kg."