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Soviet Union's IS-2¹, JS-2^10,11 heavy tank

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IS-2 heavy tank:	IS-2 heavy tank:	IS-2M heavy tank: Hradec Kralove in Bohemia, Czechoslovakia, in May 1945.	IS-2M heavy tank: Berlin, April 1945.

Design

After the Battle of Kursk it was realized that larger guns than 85 mm were needed.¹ Kotin's team at Zavod Nr 9 initially placed an 85 mm gun in the IS series but it was then determined that a 100 mm or 122 mm gun was needed.¹ The 100 mm BS-3 and 122 mm A-19 were put through tests in November 1943.¹ The 100 mm was better at armor penetration but the 122 mm could rip off the armor of a captured Panther.¹ The 122 mm was selected as it was available and the 100 mm was in very short supply.¹

Based on the IS-1 with a longer turret to accept the 122 mm, which was designed by General A. A. Petrov.² Initially had a single chambered muzzle brake which later became a double chamber after a test which almost fatally wounded Marshal K. E. Voroshilov.¹

The ammunition was in 2 parts which slowed it's loading. An IS-2's crew could fire around 2 or 3 rounds a minutes.¹ In 1944 the 122 mm D-25T gun was installed which had a better breech which helped its performance.¹

Type	Weight	Muzzle Velocity	Direct Fire Range	Indirect Fire Range	Penetration
Type	Weight	Muzzle Velocity	Direct Fire Range	Indirect Fire Range	500 m
		2,562'/sec⁸ 780 m/sec⁸
	25 kg²	790 m/sec²			140 mm²
APHE¹⁰		2,600'/sec¹⁰

Armor

The IS-2 had a cast hull front which was uniformly sloped, not bent as in the IS-1.^1,7 The better sloping provided better protection without an increase in weight.¹ The IS-2 could now withstand a direct hit by a 88 mm AP round at over 9,144 yards / 1,000 m.¹

Turret

The design team wanted to provide more protection in the turret, but that would have resulted in the turret being unbalanced and there wasn't time to completely redesign it.¹

Prototype

Was demonstrated to the Main Defense Commissariat and was accepted for production on October 1943.⁸

Production

The first one was finished in January 1944 at the Chelyabinsk factory.²

IS-2: 3,800, 3,854²
- 1943: 102^1,2, 35⁹
- 1944: 2,210⁹, 2,252^1,2
- 1945: 1,500^1,2, 2,350⁷
  - to May 9: 997⁹, after May 9: 1,150⁹
- Manufacturer: Soviet arsenals¹⁰

Variants

IS-2:
IS-2m: Improved fire control system which extended the effective range of the 122 mm. The driver had his observation hatch replaced by a sight slit.

Usage

A guard tank brigade had:

3 regiments
- 65 IS-2s each

First battle was in February 1944 at Korsun Shevcherkov (Chevchenkovski).²

Against Royal Tigers

In August 13, 1944, eleven IS-2s of the 71st Independent Heavy Tank Regiment blocked an attack by fourteen Royal Tigers (PzKpfw VI Ausf B) of the 501st Heavy Panzer Regiment.¹ The battle was at 656 yards / 600 m and resulted in four of the Royal Tigers being destroyed and seven damaged at a loss of three IS-2s and seven damaged.¹

	IS-2	IS-2 1944²	IS-2 M¹
Crew	Driver, loader, commander, gunner 4^{3,4,5,8,9,10,11,12}	4^1,2	4^1,2
Physical Characteristics
Weight	101,963 lb⁸, 99,200 lb, 45 tons¹², 45.3 tons^3,11, 45.5 tons⁷ 46 tons^4,5,9, 46.1 tons⁶, 50.6 tons¹⁰ 46,000 kg^3,11, 46,250 kg⁸	46 tons²	49.6 tons¹, 45,000 kg¹
Length w/gun	31' 6"¹², 31' 6.75"¹⁰, 32' 5.8"⁵, 32' 6"^3,11, 32.8'⁸, 33' 10.75" 9.83 m^6,9, 9.9 m^3,4,5,11, 10.7 m⁸	9.83 m²	33' 6"¹, 10.33 m¹
Length w/o gun	21' 10"⁷	6.77 m²
Height	8.9'^8,12, 8' 11.5"⁵, 8' 11"^3,11, 9'^7,10, 9' 6.75" 2.73 m^3,4,5,9,11, 2.74 m⁶, 2.9 m⁸	2.73 m²	2.92 m¹, 9' 6"¹
Width	10' 1.6"⁵, 10' 2"^3,11, 10' 3"^7,12, 11', 14' 3.25"¹⁰ 3.07 m^6,9, 3.09 m^3,4,5,11	3.07 m²	3.36 m¹, 11'¹
Width over tracks
Ground clearance	13.75"¹⁰, 1' 4.5" 0.42 m⁴, 0.47 m⁹	0.46 m²
Ground contact length	14' 3.25"¹⁰, 14.3'¹² 4.3 m⁹
Ground pressure	11.25 psi, 11.3 psi⁸, 11.66 psi, 12.6 psi¹⁰ 0.8 kg/cm² ⁸, 0.81 kg/cm² ⁹, 0.82 kg/cm² ⁴	0.8 kp/cm² ²
Turret ring diameter
Armament
Main	122 mm D-25^3,11 122 mm M1943 (D-25) L/43⁸ 122 mm D-25T⁶ 122 mm^4,5 122 mm L/43⁷ 122 mm M1943¹² 122 mm M1943 (D-25)¹⁰	122 mm 1943 D-25 T²	122 mm¹
Secondary
MG	3: 7.62 mm DT MG³ 4: MGs⁴ 7.62 mm MG⁵ 12.7 mm MG⁵ 12.7 mm DShK-38 MG¹⁰ 3: 7.62 mm MG¹¹		3: 7.62 mm MG¹
MG - coaxial	1: 7.62 mm DT MG^6,7 1: 7.62 mm DT or DTM MG¹⁰ 1: 12.7 mm M1938 DshK⁸	1: 7.62 mm DT MG²
MG - rear turret	1: 7.62 mm DT MG^6,7 1: 7.62 mm DT or DTM MG¹⁰	1: 7.62 mm DT MG²
MG - hull	1: 7.62 mm DT MG⁷ 1: 7.62 mm DT or DTM MG¹⁰ 1: 7.692 mm DT or DTM MG⁸	1: 7.62 mm DT MG²
MG - antiaircraft	1: 12.7 mm DShK⁷ 1: 7.62 DT MG (May 1944+)⁶	1: 12.7 mm DSchK 38²	12.7 mm AA¹
Side arms
Quantity
Main	28^{1,4,6,8,10,12}	28²
Secondary
MG	12.7: 350¹⁰ 7.62: 3,024¹⁰ 2,330¹², 2,631⁴	7.62: 2,330² 12.7: 250²
Side arms
Armor Thickness (mm)	120^3,11, 132⁵, 19 - 132⁸ Front: 160⁶ Side: 110⁶ Turret: 100⁷ Hull: 105⁷
Hull Front, Upper	4.3"@0°¹⁰, 90-120⁴, 120^9,12	120-160²	120¹
Hull Front, Lower	90-95
Hull Sides, Upper	3.5"@0°¹⁰ 89 - 90¹², 90 - 95⁴, 90⁹	90²	95¹
Hull Sides, Lower	90
Hull Rear	2"@0°¹⁰, 60^4,9	60-90²	60¹
Hull Top	20 - 30⁴, 25¹², 30⁹	20-30²	30¹
Hull Bottom	20 - 30^4,9, 25¹²	20-30²	30¹
Turret Front	3.9"@0°¹⁰, 160⁴, 30 - 100⁹, 30 - 102¹²	100²	160¹
Turret Sides	3.7"@0°¹⁰, 160 - 100⁴	90²	110¹
Turret Rear	90⁴	60-90²	100¹
Turret Top	30⁴	30²	30¹
Engine (Make / Model)	V-2-IS^3,4,5,8,11 1943: V-2-IS² V-2K¹⁰ V-2-IS (V2K)¹²	W-2-IS²
Bore / stroke		4 stroke²
Cooling	Water^8,10
Cylinders	V-12^5,8,10, 12^11,12	V-12²
Capacity
Net HP	513^11,12, 600^5,6,10 520@2,000 rpm⁸	600@2,000 rpm²
Power to weight ratio	11.3 hp/ton⁹, 13 hp/ton⁸	11.3 hp/ton²
Compression ratio
Transmission (Type)	8 forward, 2 reverse 2x4 forward, 2 reverse⁴ 5 forward, 1 reverse¹⁰ Sliding mesh¹⁰
Steering	Clutch brake¹⁰
Steering ratio
Starter
Electrical system
Ignition
Fuel (Type)	Diesel^5,8,10,11,12	Diesel²
Octane
Quantity	217 gallons, 158 gallons + 104 gallons in auxiliary tanks¹⁰ 820 liters⁴	800 liters²
Road consumption
Cross country consumption
Performance
Traverse	360°¹⁰ Electric or hand¹⁰	360°
Max speed	23 mph^3,5,8,11,12, 25 mph¹⁰, 27 mph⁷ 37 kph^{3,4,5,6,8,9,11}	37 kph²	37 kph¹, 23 mph¹
Cross country speed	15 mph
Road radius	94 miles⁸, 120 miles⁷, 149 miles^3,5,11, 150 miles¹², 160 miles¹⁰ 150 km⁸, 240 km^3,4,5,11, 130 - 240 km⁹	150 km²	155 miles¹, 149 miles¹ 250 km¹, 240 km¹
Cross country radius	130 miles¹² 110 - 125 km⁹, 210 km⁴		130 miles¹ 210 km¹
Turning radius
Elevation limits	-4° to +20°¹⁰
Fording depth	4' 3"¹⁰ 1.3 m^4,9	1.3 m²
Trench crossing	8.1'⁸, 8' 2"^5,10 2.49 m⁵, 2.5 m⁹, 2.9 m⁸	2.5 m²
Vertical obstacle	3' 3"^5,10 1 m^5,9	1 m²
Climbing ability	24° slope¹⁰	30 - 36°²
Suspension (Type)	Torsion Bar⁴ Torsion arm¹⁰
Wheels each side	6^4,10
Return rollers each side	3¹⁰
Tracks (Type)	Cast allow steel, dry pin¹⁰
Length
Width	1' 9", 2' 1.5"¹⁰, 2' 1.63"¹² 650 mm⁴
Diameter
Number of links	87-90¹⁰
Pitch	6.25"¹⁰
Tire tread	Steel⁴
Track centers/tread	97.25"¹⁰

Sources:

Russian Tanks of World War II Stalin's Armored Might, by Tim Bean & Will Fowler, 2002
Russian Tanks and Armored Vehicles 1917-1945, by Wolfgang Fleischer, 1999
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
Panzer Truppen The Complete Guide to the Creation and Combat Employment of Germany's Tank Force 1943-1945, Thomas L. Jentz, 1996
The Encyclopedia of Weapons of World War II, Chris Bishop, 1998
Jane's World War II Tanks and Fighting Vehicles The Complete Guide, Leland Ness, 2002
Tanks of World War II, Duncan Crow, 1979
Battle Winning Tanks, Aircraft & Warships of World War II, David Miller, 2000
Russian Armour Volume 1: The IS Tanks IS-1, IS-2, IS-3, Mikhail Baryatinskiy, 2006
Tank Data 2, Aberdeen Proving Grounds Series, E. J. Hoffschmidt and W. H. Tantum IV, 1969
The Illustrated Guide to Tanks of the World, George Forty, 2006
Airfix Magazine Guide 22 Russian Tanks of World War 2, John Milsom and Steve Zaloga, 1977