Saturday, 6 September 2014

IS, First Series

"Order of the People's Commissar of Tank Production of the USSR #104ss
February 25th, 1943

On the construction of experimental IS tanks

To fulfil State Committee of Defense decree #2943ss, issued on February 24th, 1943, I order that:
  1. The director of the Kirov factory, comrade Dlugach, director of factory #200, comrade Sherbakov, and chief engineer of the Kirov factory, comrade Kotin, produce two experimental IS tanks at the Kirov factory: one with the 122 mm gun (U-11), the other with a 76 mm gun (F-34), and provide them for proving grounds trials by March 10th, 1943.
  2. The GOKO decree defines the following main characteristics of the IS tanks:
    1. A maximum weight of 39.5 tons for the tank armed with the 122 mm U-11 gun, including ammunition, fuel, and crew.
    2. A maximum weight of 38.5 tons for the tank armed with the 76 mm F-34 gun, including ammunition, fuel, and crew.
    3. Armour:
      1. Front: 120/100 mm (cast)
      2. Side: 90 mm (rolled)
      3. Top and floor: 20 mm 
      4. Rear: 60 mm (sloped at 45 degrees)
      5. Turret: 100 mm (sides)
    4. Maximum speed: 55 kph.
    5. Transmission: 8 speed gearbox, planetary turning mechanism, planetary final drives.
    6. Engine: 600 hp V-2K
    7. Ammunition:
      1. No less than 30 shells for the IS tank with a 122 mm gun.
      2. No less than 80 shells for the IS tank with a 76 mm gun.
    8. Crew: 4
    9. Machineguns:
      1. With a 122 mm gun: 2 (coaxial and hull)
      2. With a 76 mm gun: 3 (coaxial, turret rear, and hull)
    10. Fuel capacity: 500 kg


  1. Hey Peter:
    Did the Soviets use metric tonnes (2204.6 pounds - tonne) or short tons (2000 pounds - ton)? I have always been amazed they were able to keep the weight of their tanks so low, in comparison to other countries... Thanks

    1. The metric tonnes (or just tonnes) of course. No one except the Americans (and back then the British and their Empire) used any imperial units.

    2. Metric tons: 1000 kg per ton. The weight of the tanks was kept low due to much greater resistance to "inflation" on the administrative end. While you see German 30 ton projects swell into 60 ton projects, a tank that was only 200 kg overweight would result in many fists shaken and much paper spent until it was within required parameters.