Friday 24 August 2018

IS Upgrades

"May 19th, 1944

List of work for the modernization of the IS-2 tank and ISU-152 SPG
  1. Engine group
    1. Installation of an Object 701 type radiator.
    2. Installation of a horizontal fan.
    3. Installation of fuel tanks in the engine compartment.
    4. Redesign of the oil system caused by a change in layout.
    5. Redesign of the water system caused by a change in layout.
    6. Replace the exhaust with T-34 type.
    7. Introduce shutters on the air intake.
  2. Transmission group
    1. Alteration of the main friction clutch to accommodate the fan linkage.
    2. Redesign the gearbox to accommodate the fan linkage.
    3. Installation of an Object 701 type fan linkage.
  3. Electric equipment
    1. Installation of four batteries.
    2. Installation of an ST-700 starter.
  4. Hull
    1. Straight front plate 90 mm thick for rolled armour or 100 mm thick for cast armour, 130 mm thick turret platform front, Object 701 type "cork" driver's vision port.
    2. Alteration of the engine deck to accommodate changes in the water system.
    3. Alteration of the exhaust armoured covers.
  5. Armament
    1. Thickening of the front of the turret to 130 mm with the installation of the gun through the roof, similar to Object 701.
    2. Object 701 style traverse mechanism.
    3. Object 701 type turret ring.
    4. Object 701 type low profile commander's cupola.
    5. Rework of the ammunition racks to increase ammunition capacity.
    6. Installation of a high caliber DShK AA machinegun.
The aforementioned items must be completed on each of the two experimental IS tank and SPG prototypes built according to this order.

Head of the Chief Designer's Department of the NKTP, Ber
Chief of the GBTU TU, Major-General of the Tank Engineering Service, Afonin"


  1. Looking at this list, was this only limited for two experimental vehicles, or did some of these changes make it to production? (I am thinking that the hull armor 'front turret platform' going up to 130 mm was implemented in the IS-2 mod 1944, don't think the 130 mm front turret armor was (unbalanced the turret unless a major redesign), nor was the ammo supply increased). Some of the engine/transmission/electrical stuff might have been implemented, but even Baryatinskiy doesn't mention all these.

    1. Some changes did, others did not. You're right that the wishlist had to be balanced against what could be introduced into production without upsetting thing too much. Some things were implemented, but took ages. For instance, the AA DShK mount took until the end of the year to be implemented.