IS tank family
This article needs additional citations for
|Iosif Stalin tank|
|Place of origin|
|Used by||Soviet Union, China, Cuba, Czechoslovakia, DPRK, Egypt, Poland|
|Unit cost||IS-2 Model 1944: 264,400 rubles|
|Specifications (IS-2 Model 1944)|
|Weight||46 tonnes (51 |
|Length||9.90 m (32 ft 6 in)|
|Width||3.09 m (10 ft 2 in)|
|Height||2.73 m (8 ft 11 in)|
|IS-2 Model 1944:|
Hull front: 100 mm at 60° angle
Lower glacis: 100 mm at 30° angle
Turret front: 100 mm (rounded)
Mantlet: 155 mm (rounded)
Hull side: 90–130 mm at 9-25°
Turret side: 90 mm at 20° angle.
|Engine||12-cyl. diesel |
600 hp (450 kW)
|Fuel capacity||820 l (180 imp gal; 220 US gal)|
|240 km (150 mi)|
|Speed||37 km/h (23 mph)|
The IS Tank was a series of
The capture of a German
The Object 237 prototype, a version of the cancelled
By 1943, engineers had succeeded in mounting the 85 mm gun to the T-34 medium tank, making it as well-armed as the KV-85 heavy tank. Efforts to up-gun the IS-85 began in late 1943. Two candidate weapons were the D-25 122 mm tank gun, the ballistic characteristics of which were identical to the
After testing both the D-25 and D-10 on the IS-122, the former was selected as the main armament of the new tank. The D-25 used a separate shell and powder charge, resulting in a lower rate of fire compared to the single-piece ammunition used in most tanks, a serious disadvantage in tank-to-tank engagements. Soviet proving-ground tests showed that the D-25 could penetrate the front armor of the German Panther tank at 2,500 m (2,700 yd) while the D-10 could do so at a maximum range of 1,500 m (1,600 yd). It was therefore considered an adequate anti-tank gun.
A Wa Pruef 1 Report dated 5 October 1944 has data on the penetration ranges of the 122 mm A-19 gun against a Panther tank angled at 30 degrees; this estimated that the A-19 gun was unable to penetrate the upper glacis plate of the Panther from any distance, could penetrate the lower glacis plate from 100 m (110 yd), could penetrate the mantlet from 500 m (550 yd) and could penetrate the front turret from 1,500 m (1,600 yd). The Panther's 40–50 mm (1.6–2.0 in) thick side armor would have been exposed and vulnerable at such an angle; the sides at 30 degrees were penetrable from over 3,500 m (3,800 yd) according to the same Wa Pruef 1 report. Testing with captured
According to the same Wa Pruef 1 report, it was estimated that at 30 degree obliquity the hull armor of the Soviet
The large 122 mm
The most recognizable disadvantage of the D-25T gun was its slow rate of fire due to the large size and weight of the shells; only one to one and a half rounds per minute could be fired, initially. After some design improvements, including a semi-automatic drop breech over the previously manual screw breech, the rate of fire increased to 2–3 rounds per minute., and according to other sources, the increase may have amounted to 3–4 rounds per minute. Another limitation imposed by the size of its ammunition in a relatively small vehicle was the ammunition stowage: only 28 rounds could be carried inside the tank, with a complement of 20 HE rounds and 8 AP rounds the norm.
The IS-122 prototype replaced the IS-85 and began mass production as the IS-2. The 85 mm guns could be reserved for the new T-34-85 medium tank and some of the IS-1s built were rearmed before leaving the factory and issued as IS-2s. It was slightly lighter and faster than the heaviest KV model 1942 tank, with thicker front armor and a much-improved turret design. The tank could carry thicker armor than the KV series, while remaining lighter, due to the better layout of the armor envelope. The KV's armor was less well-shaped and featured heavy armor even on the rear, while the IS series concentrated its armor at the front. The IS-2 was slightly lighter than the
Early IS-2s can be identified by the 'stepped' front hull casting with its small, opening driver's visor. The early tanks lacked gun tube travel locks or anti-aircraft-capable machine guns and had narrow mantlets.
In late 1944, the stepped hull front was replaced with an improved single casting of 120 mm thickness angled at 60 degrees. This new nose lacked the opening driver's visor. It is sometimes incorrectly referred to as the IS-2M, but that designation actually refers to a much later modernization program from the 1950s. Other minor upgrades included the addition of a travel lock on the hull rear, wider mantlet and, on very late models, an
In comparison to the Tiger I, the IS-2 had modest advantages in armour, even though it was 10 tons lighter
In the mid-1950s, the remaining IS-2 tanks (mostly model 1944 variants) were upgraded to the IS-2M standard, which introduced fittings such as external fuel tanks on the rear hull (the basic IS-2 had these only on the hull sides), stowage bins on both sides of the hull and protective skirting along the top edges of the
There are two tanks known as IS-3: Object 244 was an IS-2 rearmed with the long-barrelled 85 mm cannon (D-5T-85-BM) and developed by LKZ (in Leningrad), which was never series-produced for service use.
Object 703 was developed in late 1944 by ChTZ (in Chelyabinsk) and left the factory shop in May 1945. This tank had an improved armour layout, and a semi-hemispherical cast
The IS-3 came too late to see action in World War II. The first public demonstration of the IS-3 came on 7 September 1945 during the
There are two tanks known as IS-4: Objekt 245 and Objekt 701. Objekt 245 was an IS-2 rearmed with a long 100 mm D-10T cannon. The other IS-4 was a new vehicle projected by LKZ in parallel with the IS-3 known as Objekt 701 by the same design and development bureau. For the latter, the IS-2 hull was lengthened, with an extra set of road wheels added and an improved engine. Both hull and turret armor were increased. Several alternative armaments were explored in paper studies but ultimately the IS-2's original 122 mm gun was retained. An effort was also made to make use of technical data derived from study of the German wartime
There existed two different IS-6s: the Object 253 was an attempt to develop a practical electrical transmission system for heavy tanks. Similar systems had been tested previously in France and the United States and had been used with some success in the German
The armour was engineered in a similar fashion to the IS-3, with a pike nose on the upper glacis. When shot at frontally, the extreme angle that the pike nose presents results in a much higher likelihood of a ricochet. Thus, the armour protection could be enhanced without having to use excessive amounts of materials. However, if the pike nose was shot at a sideways angle, it would not have a relative thickness high enough to ricochet the shell. In spite of its weight, it was easy to drive due to numerous hydraulic assists. The loaders noted that the IS-7 was comfortable and that the autoloader was easy to use. It was also able to achieve a top speed of 60 km/h thanks to a 1050-horsepower engine giving it a power to weight ratio of 15.4 hp/tonne, a ratio superior to most contemporary medium tanks. Its armour was not only immune to the
The IS-10 (also known as Objekt 730) was the final development of the KV and IS tank series. It was accepted into service in 1952 as the IS-10, but due to the
The biggest differences from its direct ancestor, the IS-3, were a longer hull, seven pairs of road wheels instead of six, a larger turret mounting a new gun with fume extractor, an improved diesel engine, and increased armour. General performance was similar, although the T-10 could carry more ammunition.
T-10s (like the earlier tanks they replaced) were deployed in independent tank regiments belonging to armies, and independent tank battalions belonging to divisions. These independent tank units could be attached to mechanized units, to support infantry operations and perform breakthroughs.
The T-10M is the final iteration of this type. It featured a longer gun barrel than previous models with 5-baffle muzzle brake and 14.5 mm machine gun. This was the last Soviet heavy tank to enter service. When the advanced
||122 mm |
|Secondary armament||2×45 mm
|45 mm||45 mm||2×
|500 hp||850 hp
|600 hp |
||910||–||–||600||600||600||975||975||820||520 + 270|
|Road speed (km/h)||30||35||36||35||35||28||45||40||37||37|
|Road range (km)||150||–||150||335||335||250||250||250||240||150 (225)|