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Soviet Union's IS-85, IS-1, JS-1 heavy tank

Design

IS stood for Iosef Vissarionovich Stalin / Iosef Stalin.

The need to increase the firepower of the KV series was seen by the end of 1942 with the Germans introducing Tiger tanks a new tank was needed to combat it. The IS-85 was intended to be a 4-man tank, with an 85 mm gun, not weigh more than a KV-1, and that had thick enough armor to defeat the German 50 mm anti-tank gun.

The IS-85 was designed by a design bureau led by Lieutenant-Colonel Kotin. He split the bureau into two and each team had different specifications to design for. One of the teams was told to improve the KV series as a stopgap for a new heavy tank. This design was to become the KV-85. The other team was to design the new heavy tank, the IS-85. The team was headed by, released from a labor camp, N. V. Tseits.The design was initially called the KV-13 and had a redesigned hull and chassis from the KV series.

Based on the KV series it had a new hull, improvements in the suspension, transmission, and power train. The turret was cast and the hull had cast and rolled parts welded together.

Main Armament

The IS-85's design first started out with same 85 mm gun as the T-34/85 and a few were produced in late 1943. The cast turret (which was used in the KV-85) was designed by General A. A. Petrov. A heavier gun was needed as the T-34/85 was being produced and having a heavy tank with the same armament as a medium was thought to be inefficient. The 100 mm designed by V. Grabin was tried with great success and known as the IS-100. The 122 mm was tried but it was only a little more effective, however the 100 mm was in short supply. The superstructure extended out over the tracks and this allowed for a bigger turret.

There was no machine gun in the hull which allowed for a better ballistic shape.

Prototype

A design bureau was headed by N. F. Shashmurin at Tankograd in the Urals that developed the IS series. By the end of 1943 prototypes were available.

Only a short test was done and the State Defense Committee approved the tanks for use in the Red Army in October 1943.

The KV-13 prototype was tested at Chelyabinsk's Experimental Test Factory in May 1942. It was found to have problems with the transmission and would often throw a track.

Production

After a few models were produced, production was switched to the IS-2. The models that were left were converted to IS-2 standards.

In 1943 the IS-85 was redesignated the IS-1.

  • IS-1:
    • 1943: 100, 67
    • 1944: 40

Variants

  • KV-9: Prototype. 122 mm howitzer.
  • KV-13: Prototype.
  • IS-85, IS-1 (85), IS-1: 85 mm gun.
  • IS-100: 100 mm gun.
  • IS-1 (122), IS-1B:

Usage

Some saw action in the Ukraine in early 1944.

Specifications

  IS-1, IS-1 (85), IS-85
Crew 4
Physical Characteristics  
Weight 97,000 lb
44 tons, 45.3 tons
46,000 kg
Length

27.3', 27' 3", 29' 4"
8.32 m, 8.56 m

Height 8.9', 9' 6"
2.735 m, 2.9 m
Width 10' 3", 10' 8", 11'
3.07 m, 3.25 m
Width over tracks  
Ground clearance 0.47 m
Ground contact length 14.3'
4.3 m
Ground pressure 0.78 kp/cm2
Turret ring diameter  
Armament  
Main 1: 85 mm
1: 85 mm M1943
1: 100 mm
Secondary  
MG 2: 7.62 mm DT MG
4: MG
2: 7.62 mm MG
3: 7.62 mm MG
MG - antiaircraft 1: 12.7 mm DShK
Side arms  
Quantity  
Main 71
Secondary  
MG 1,330
Side arms  
Armor Thickness (mm) 19 - 120, 30 - 132, 132
Hull Front, Upper 120 - 160, 120
Hull Front, Lower  
Hull Sides, Upper 89 - 90, 90
Hull Sides, Lower  
Hull Rear 60
Hull Top 25, 30
Hull Bottom 25
Turret Front 30 - 100
Turret Sides  
Turret Rear  
Turret Top  
Engine (Make / Model) V-2-IS, V-2-IS (V2K), V2-IS
Bore / stroke  
Cooling  
Cylinders 12
Capacity  
Net HP 510, 513
Power to weight ratio 11.8 hp/ton
Compression ratio  
Transmission (Type)  
Steering  
Steering ratio  
Starter  
Electrical system  
Ignition  
Fuel (Type) Diesel
Octane  
Quantity  
Road consumption  
Cross country consumption  
Performance  
Traverse 360°
Speed - Road 23 mph, 24.8 mph, 24.9 mph
37 kph, 40 kph
Speed - Cross Country 15 mph
Range - Road 149 miles, 150 miles, 155 miles
130 - 240 km, 250 km
Range - Cross Country 130 miles
110 - 125 km
Turning radius  
Elevation limits  
Fording depth 1.3 m
Trench crossing 2.5 m
Vertical obstacle 1 m
Climbing ability  
Suspension (Type)  
Wheels each side  
Return rollers each side  
Tracks (Type)  
Length  
Width 2' 1.63"
Diameter  
Number of links  
Pitch  
Tire tread  
Track centers/tread  
  IS-1 1943, IS-1A
Crew 4
Physical Characteristics  
Weight 44 tons
Length w/gun 8.56 m
Length w/o gun 6.77 m
Height 2.73 m
Width 3.07 m
Width over tracks  
Ground clearance 0.46 m
Ground contact length  
Ground pressure 0.78 kp/cm2
Turret ring diameter  
Armament  
Main 85 mm M1943 D-5 T
85 mm or 100 mm
Secondary  
MG - coaxial 1: 7.62 DT MG mm
MG - rear 1: 7.62 DT MG mm
MG - hull 1: 7.62 DT MG mm
Side arms  
Quantity  
Main 59
Secondary  
MG 2,520
Side arms  
Armor Thickness (mm)  
Hull Front, Upper 120 - 160
Hull Front, Lower  
Hull Sides, Upper 90
Hull Sides, Lower  
Hull Rear 60
Hull Top 20-30
Hull Bottom 20-30
Turret Front 100
Turret Sides 90
Turret Rear 60-90
Turret Top 30
Engine (Make / Model) W-2-IS
(V-2K)
Bore / stroke 4 stroke
Cooling  
Cylinders V-12
Capacity  
Net HP 600@2,000 rpm
Power to weight ratio 14.1 hp/ton
Compression ratio  
Transmission (Type)  
Steering  
Steering ratio  
Starter  
Electrical system  
Ignition  
Fuel (Type)  
Octane  
Quantity 800 liters
Road consumption  
Cross country consumption  
Performance  
Traverse  
Speed - Road 37 kph
Speed - Cross Country  
Range - Road 150 km
Range - Cross Country  
Turning radius  
Elevation limits  
Fording depth 1.3 m
Trench crossing 2.5 m
Vertical obstacle 1 m
Climbing ability 30 - 36°
Suspension (Type)  
Wheels each side  
Return rollers each side  
Tracks (Type)  
Length  
Width  
Diameter  
Number of links  
Pitch  
Tire tread  
Track centers/tread  
  IS-1B, IS-1 (122)
Crew 4
Physical Characteristics  
Weight 44.5 tons
Length 31' 6"
Height 8.9'
Width 10' 3"
Width over tracks  
Ground clearance  
Ground contact length 14.3'
Ground pressure  
Turret ring diameter  
Armament  
Main 122 mm
122 mm M1943
Secondary  
MG 3: 7.62 mm MG
MG - antiaircraft 1: 12.7 mm DShK
Side arms  
Quantity  
Main 28
Secondary  
MG 2,330
Side arms  
Armor Thickness (mm)  
Hull Front, Upper 120
Hull Front, Lower  
Hull Sides, Upper 89 - 90
Hull Sides, Lower  
Hull Rear  
Hull Top 25
Hull Bottom 25
Turret Front 30 - 102
Turret Sides  
Turret Rear  
Turret Top  
Engine (Make / Model) V-2-IS (V2K)
Bore / stroke  
Cooling  
Cylinders 12
Capacity  
Net HP 513
Power to weight ratio  
Compression ratio  
Transmission (Type)  
Steering  
Steering ratio  
Starter  
Electrical system  
Ignition  
Fuel (Type) Diesel
Octane  
Quantity  
Road consumption  
Cross country consumption  
Performance  
Traverse  
Speed - Road 23 mph
Speed - Cross Country  
Range - Road 150 miles
Range - Cross Country 130 miles
Turning radius  
Elevation limits  
Fording depth  
Trench crossing  
Vertical obstacle  
Climbing ability  
Suspension (Type)  
Wheels each side  
Return rollers each side  
Tracks (Type)  
Length  
Width 2' 1.63"
Diameter  
Number of links  
Pitch  
Tire tread  
Track centers/tread  

Sources:

  1. Russian Tanks of World War II Stalin's Armored Might, by Tim Bean & Will Fowler, 2002
  2. Russian Tanks and Armored Vehicles 1917-1945, by Wolfgang Fleischer, 1999
  3. The Encyclopedia of Tanks and Armored Fighting Vehicles - The Comprehensive Guide to Over 900 Armored Fighting Vehicles From 1915 to the Present Day, General Editor: Christopher F. Foss, 2002
  4. Tanks of the World, 1915-1945, Peter Chamberlain, Chris Ellis, 1972
  5. Tanks of World War II, Duncan Crow, 1979
  6. Russian Armour Volume 1: The IS Tanks IS-1, IS-2, IS-3, Mikhail Baryatinskiy, 2006
  7. The Illustrated Guide to Tanks of the World, George Forty, 2006
  8. Airfix Magazine Guide 22 Russian Tanks of World War 2, John Milsom and Steve Zaloga, 1977
  9. The Encyclopedia of Weapons of World War II, Chris Bishop, 1998
  10. World War I and II Tanks, George Forty, 2012
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