IS-1 (Object 237) Characteristics

"Tactical-technical characteristics of the IS tank

1. Full combat weight: 43-44 tons
2. Crew: 5
3. Armour
1. Front: at least 120 mm thick, cast
2. Side: at least 90 mm thick, rolled
3. Floor and roof: at least 20 mm thick, rolled
4. Rear: at least 60 mm (at an angle of 45 degrees), rolled
5. Turret: at least 100 mm, cast
4. Armament:
1. 85 mm gun with AA gun ballistics
2. 3 DT machineguns, one coaxial, one in the front hull, operated by the driver, one in the rear of the turret (doubles as AA machinegun).
3. 2 submachineguns
5. Ammunition:
1. At least 60 85 mm rounds
2. At least 3000 machinegun rounds
3. At least 500 submachinegun rounds
4. At least 25 F-1 grenades
6. 600 hp V-2K engine with an inertial starter
7. Top speed of 35-37 kph
8. 500 kg capacity of main fuel tanks
9. Transmission: mechanical, normal type, with a planetary turning mechanism instead of friction clutches. Planetary final drives.
10. Observation devices:
1. Commander's observation cupola with triplex observation devices in the sides and an English periscope in a rotating hatch.
2. 3 triplex observation devices: 1 for the driver and two in the sides of the turret.
3. 3 English type periscopes, of them:
1. 2 for the driver
2. 1 for the loader in the turret
11. Communication equipment:
1. External: 10R radio in each tank.
2. Internal: intra-tank communication device
12. Turret ring diameter: at least 1800 mm.

GBTU Chief, Lieutenant-General of the Tank Forces, Vershinin

GBTU Tank Department Chief, Engineer-Colonel Afonin

May 4th, 1943"

CAMD RF 38-11355-1380 pp 185-186