Categories
WWII Soviet Heavy Tanks

T-35A Heavy Tank

Soviet Union (1934)
Heavy tank – 61 built

The Eastern Behemoth

The T-35A tank is one of history’s strangest tanks – often seen crawling across the Soviet inter-war era parade squares. This tank grabbed the hearts, souls, and imaginations of the Soviet people and foreign military attachés alike. It was one of the many proud achievements of Soviet industrialisation – its image appeared on posters, films, and even medals and awards.

Prototyping

The initial T-35-1 and T-35-2 prototypes were both evaluated by the Red Army, but were not accepted for service. This was due to a new design buro designing a similar, yet superior machine. The OKMO (Opytniy Konstruktorsko-Mekhanicheskiy Otdel, ‘Experimental Design Mechanical Department’) bureau of Kharkov, in parallel with the T-35-2, had designed the T-35A prototype. Similarly to how the T-37 and T-37A were different vehicles with similar names, the two tanks shared similarities but were, by and large, different vehicles.
A part of the reason for this change was the Soviet leader, Stalin himself becoming interested in the project and decreeing that the new T-35 and T-28 medium tank should share as many parts as possible.

An early production T-28 tank lost in the opening days of Barbarossa. The main turret and machine gun turrets were all borrowed from the T-28 and implemented onto the T-35. Source: Francis Pulham Collection.
The new tank was longer, which required the addition of an extra suspension bogie. The turrets were also redesigned. The 45-mm gun turrets were now round with room for two crewmen to operate a more potent K-20 gun, replacing the previous PS-3 37mm gun. The machine gun turrets were very similar to the secondary turrets on the T-28 medium tank. These turrets were originally produced in Leningrad, and copied for the T-35A tank.
The exhausts were moved from the fenders to the main body of the tank. This was done to protect the exhaust from damage. Finally, the main turret was now elliptical. It was identical to the main turret of the new T-28 tank. It featured a 76.2-mm KT-28 gun, an electrically powered turret traverse system, and complex electronics that indicated to the commander a number of turret positions. In addition, a 71-KT- 1 radio, with distinctive ‘clothesline’ antenna was added around the turret.
A T-35A before the addition of the P-40 AA mount. This scheme is from the 1936 summer maneuvers.
A T-35A before the addition of the P-40 AA mount. This scheme is from the 1936 summer maneuvers.

Production T-35s

The T-35A (that is often just called the T-35) did not have an official prototype, and production began in August 1933. This, however, did not go ahead as planned, as the T-35 was a very complex machine to manufacture.
The tank was assembled from nine separate pre-made frames and assembled on a jig. The original plan was to manufacture the first machine by the 1st of November 1933, however, the first production machine (chassis number 148-11) did not roll off the production line until January 1934.

Description of the T-35

The T-35 tank was 9.72 metres long by 3.2 metres wide by 3.43 metres high, and weighed 54 tonnes. The tank was powered by the M-17L aero engine that had an output of 580 hp, able to propel the tank at speeds up to 28 km/h on roads and 14 km/h off road. The hull was manufactured from plates that were 20 mm thick on the sides, 10 mm on the roof and floor and 30 mm on the glacis and nose. The hull sides had four hard points for the bogies of the tank, and a drive sprocket at the rear.
The running gear consisted of four bogies. Each bogie was made up of four coiled spring suspension arms in two pairs, with two pairs of road wheels in between them. There was a drive sprocket at the rear of the tank, and 6 return rollers, which were the same as the T-28’s road wheels. The track consisted of 135 links that were 526 mm wide.

A factory photograph of the T-35A’s running gear. Source: Land Battleship: The Russian T-35 Heavy Tank
In between the bogies were supporting brackets that attached to a skirt of metal that was on the exterior of the hull. These skirts were made from 5 plates, 10 mm thick, and attached to the bogie and the return roller support. This skirt was attached to a frame on the inside, and individual skirt parts could be removed. The skirt was attached to the fender, which ran from the front of the tank to the rear of the tank, and was where all of the equipment for the tank was stowed.
The engine deck consisted of a central hatch to access the engine, with two air intakes for the radiators either side of the engine access hatch. Behind this was the exhaust, which was originally an exterior exhaust with an armored cover for the front and sides. The rear of the tank sloped downwards, where a huge fan was located. This fan had a cover, which was attached to the tank by hinges, and has vertical slats on it to allow for air flow. Below this were two rear transmission hatches.

T-35A 288-43 exposing the engine deck. Notice the central hatch, flanked with two radiator air intakes. To the rear is the fan and fan cover. The slats could be opened or closed to allow for better airflow. Source: Francis Pulham Collection.
The tank had five turrets in the front two-thirds of the tank. These were arranged around a central turret pedestal. 45 mm turrets were placed in the front right and rear left, with MG turrets on the front left and rear right. The MG turrets were redesigned MG turrets from the T-28 tank, and were equipped with a ball mounted DT-29 machine gun. This turret had a single hatch, and a single vision port to the left.
The 45 mm gun turret was round, with a 45 mm K20 gun. The armor was 20 mm thick, and on the turret interior walls was 45 mm gun ammunition. Three racks were carried, one between the two vision ports on the right, one against the rear wall of the turret and one on the right wall. The rear ammunition rack could be removed, exposing a door at the rear of the turret that allowed for gun removal and maintenance.

T-35A 220-28 displaying the interior of the rear 45mm gun turret. Notice the stowage for the 45mm ammunition. Source: “Fallen Giants: The Combat Debut of the T-35A Tank”, and the Francis Pulham Collection.
There was also a magazine rack in this turret with enough space for seven magazines of thirty MG? rounds, This gave a total of 210 rounds. This turret had a crew of two men, a gunner and a loader. The gunner was also equipped with a T-71-1 periscope. The turret roof also had a smoke extractor and two hatches for the crew.
The main turret sat on a pedestal that elevated it above the 45 mm gun turrets. The main turret was elliptical in shape, with a slightly off-set K-28 76.2 mm gun. To the gun’s right was a cheek-mounted DT-29 machine gun in a ball mount. To the left of the gun was the turret traverse mechanism.
The turret was connected to a rotating floor plate by five arms. On the rotating turret floor were two seats for the gunner and the loader, with stowage for six 76mm rounds underneath each seat. Directly underneath the KT-28 gun was an ammunition rack for DT-29 machine gun ammunition. On the rear arm that connected the turret to the rotating turret floor was a folding seat for the commander.

T-35A 0200-0 displaying the turret roof of the T-35.Notice the twin periscopes, the two hatches for the crew and just visible is the pressed star on the turret roof. Source: “Fallen Giants: The Combat Debut of the T-35A Tank”, and the Francis Pulham Collection.
The turret roof was equipped with two TP-1 periscopes for the gunner and the loader. The first tanks were issued with turrets with a single square turret hatch for the crew. The later tanks were issued with a second hatch for the loader, and a P-40aa mount for the commander/gunner hatch. The turret roof had a pressed star between the two periscopes. The roof also had small spring stoppers for the main hatches.
The walls of the pedestals were equipped with ammunition racks for the 76.2mm ammunition and 7.62mm DT-29 machine gun ammunition. Within the turret and pedestal was a 71-TK-1 radio set and the tanks were all issued with ‘clothes line’ antennas. Ninety-six rounds of 76.2mm ammunition were carried, and 226 rounds of 45 mm ammunition. In addition, 10,080 rounds of DT-29 ammunition were carried in 380 magazines. The rear of the main turret also had a port for a DT-29 machine gun, however, no ball mount was issued until production of conical T-35s began.
The tank had a crew of ten: three crewmen in the main turret (commander, gunner, and loader), two in the 45 mm gun turrets (gunner, loader), one crewman in each machine gun turret, and the driver.
There was a production issue in 1936 that meant a batch of hulls were issued with 23 mm plates; and it was not until 1938 that the thickness of the tanks armor was increased. The T-35 as described until now is sometimes known as the ‘Cylindrical Turreted T-35’. Later production T-35s were manufactured with conical shaped turrets, sometimes known as “Conical Turreted T-35”.

Year 1934 1935 1936 1937 1938 1939
Chassis numbers 148-11 339-30 220-25 0197-1 0197-2 744-62
148-19 339-48 220-27 0197-6 0197-7 744-63
148-22 339-75 220-28 0217-3 0200-0 744-64
148-25 399-79 220-29 196-94 0200-4 744-65
148-30 399-78 220-43 196-95 0200-8 744-66
148-31 288-11 288-43 196-96 0200-5 744-67
148-39 288-14 288-65 988-15 0200-9
148-40 288-41 288-74 988-16 234-34
148-41 183-3 988-17 234-35
148-50 183-5 988-18 234-42
183-7 744-61
537-70
537-80
537-90
715-61
715-62

The table of production of the T-35A.

Production of the T-35A 1934-1937

Production started in 1934 and, by 1939, sixty-one vehicles were produced, ten of which were conical turreted T-35s. Throughout production, improvements were constantly being made.
Each tank had a chassis number, and these were made in batches, often not exceeding 5 tanks. The batch number was always three numbers, a hyphen, then one or two numbers.
The first production machines were those of the ‘148’ chassis numbers, starting with ‘148-11’. These machines were mainly identifiable from other T-35s by the turrets. The turret was constructed with a single strip of strengthening armor on the turret side, and the clothesline antenna was equipped with six arms that attached the antenna ring to the turret.

T-35A 148-30 as seen in Kharkov on October 22nd, 1941. The tank has been moderately upgraded with the removal of the clothesline antenna. Before this, the tank was re-issued an eight armed antenna.
The next batch of tanks, ‘339’ chassis numbers, starting with ‘339-30’, differed by having eight antenna arms attaching the antenna ring to the turret.
There were no major changes noted between the ‘330’ and the ‘288’ chassis numbered T-35s, although the ‘220’ T-35s did differ from the earlier tanks. The main turret was now equipped with two strips of turret support. This was likely due to cracking of the turret armor during production and in the field.
The 1936 ‘288’ and ‘183’ numbered chassis tanks reverted back to one turret strip of support, however, the two strips returned in the ‘537’ chassis tanks.

T-35A 537-70 after abandonment and capture. The Germans have painted a white warning on the front fender, as this tank was abandoned on the roadside. White triangles for air identification were common in the 67th Tank Regiment.
In 1936, the first major changes occurred. The main single turret hatch was replaced with two hatches and a P-40 anti-aircraft gun mount was added. The first tanks equipped with the P-40 mount was the 615 chassis numbered T-35s.
‘0217-35’ has not been identified in the photographic record, so unfortunately no information can be presented on this single machine.
Chassis numbers starting with ‘148’, ‘339’, ‘288’, ‘220’, ‘228’, ‘183’, and ‘537’ all had a single turret hatch (a total of thirty-one tanks), while chassis numbers ‘715’, ‘0197’, 217’, ‘196’, ‘988’, and ‘0200’ all had P-40 AA mounts (a total of nineteen tanks).

A cylindrical T-35A being inspected by German troops after it was abandoned by its crew. Source: Bronson, British Collectors of Arms & Militaria Forum.

Experiments with ‘183-5’ 1937 and 1938

After the summer maneuvers of 1936, major complaints were made against the T-35. Crews were unhappy with how unreliable the tanks were, with problems affecting nearly every aspect of the T-35.
The tank’s engine and transmission were prone to breakdown, and overheating was a major issue. The tanks often accumulated mud and debris between the drive wheel and the side skirt, which led to drivetrain failure. The crews had issues communicating, and the commander’s task was almost impossible, as he had too many responsibilities.
Some of the issues were inherent to the T-35A’s design. As the tank was so large, with so many turrets, there was little Soviet engineers could do to fix crew issues. Engine problems and gearbox problems were also inherent to long thin tanks such as the T-35, however after the summer maneuvers of 1936, T-35A ‘183-5’ was returned to the KhPZ (Kharkov Locomotive and Tractor Works) for testing.
During the testing, many items were evaluated and changed, some only minor and some major. While testing was being conducted, tanks were still being manufactured, so it was not until the 196 chassis numbers were on the workbench did two of the three tanks get selected to be improved upon for experiments.
‘196-94’ and ‘196-95’ were not assembled as regular T-35As, and were issued with unique features to the other T-35s. The rear part of the side skirt was removed to prevent mud build up around the drive wheel – something which often caused major problems with the track during maneuvers. The skirts were now fitted with triangular inspection ports, and the smoke generators were made homogeneous with the sub turret structure. This was applied to chassis numbers ‘196-94’ and ‘196-95’. After twelve more tanks were produced to the previous specification, production modernised to the new standard.
T35A
196-95 as seen at the Gorodok Repair Centre in July 1941. Despite the huge opportunity to decorate the T-35 tanks, only 196-95 was done so. The smoke generators had a small brass Lenin plack, and the glacis plate had a small plate with “In honor of the XXth anniversary of the October Revolution” written onto it.
Along with the major changes, minor improvements were made. For example, the exhaust pipe was moved under the armor of the tank, the driver’s vision hatch was improved upon and enlarged. The armor on the machine gun turret faces was deemed inadequate, so a new circular piece of armor was placed over it, and a splash guard was placed onto the ball mount in the turret cheek of the tank.

T-35A 196-94 was one of the two prototype T-35s that incorporated the changes recommended upon testing of 183-5. Most noticeable is the hatches in the skirts, but there were other changes such as redesigned turret pedestal and transmission covers. Source: Francis Pulham Collection
These changes were also implemented onto the regular T-35s that were being produced, but not all tanks were issued the new pattern items.
Only ‘196-94’ and ‘196-95’ were issued the experimental hulls, and ‘196-96’ was a standard T-35.
The only chassis numbered T-35s of interest in this period of change was the ‘988’ chassis number series. These machines did not have any of the updates made to them at the other T-35s where issued with. The tanks still had an exterior exhaust muffler, and did not equip the new driver’s vision hatch or the amplified machine gun faces.

988-15 had no updates made to it. The early exhaust can be seen on the rear of the tank. 988-15 was also the only T-35 that had a tactical number painted onto it, this being “14”.
Note should be made that all T-35s needed overhauling at least once in their service careers. Upon returning to the factories, many tanks were repaired and updated to the new pattern of exhausts or driver’s hatches. All ‘148’ tanks either had their six armed antennas replaced with eight armed ones, or had them removed entirely.
Two ‘148’ tank were given a major overhaul. ‘148-22’ and ‘148-25’ both had a P-40aa mount equipped onto the turret, along with machine gun turret amplification, and the 1937 pattern of driver’s escape hatch. This hatch was two doors that were hinged together and collectively hinged to the left outwards, whereas the original hatch was two doors that were separate and when opened, the left door was free to move, but the right door interfered with the 45 mm gun turret
Almost every T-35 had some upgrades made to them. Only ‘220-28’ and the ‘988’ tanks, along with the conical turreted T-35s, did not get updated.
The 1939 pattern of updating the T-35s was more obvious, with the drivers hatch being replaced with the ‘BT’ type circular hatch, and the front idler wheel being replaced with a pressed wheel, rather than a cast wheel with spokes. ‘220-25’ and ‘537-70’ are both known to have had this update made.

Conical turreted T-35s

In 1938, the Red Army wanted to modernize many of the tanks on their production lines. The biggest flaw with the production T-35 by 1937 was that the armor was too thin. There was a myriad of other issues, however, the modernization of the T-35 would focus on this issue.
From mid-1938 to 1939, the last ten T-35 tanks were issued new hulls and new turrets. The hull of these new tanks was taken from the experimental chassis tanks, 196-94 and 196-95, that had side skirts which did not cover the drive wheel and triangular inspection ports in the skirts, five instead of six return rollers, an altered stowage layout, and a homogenous turret substructure.
Initially, there were mixed orders on how to modernize the T-35, with one directive requiring armor of 40-45mm on the hull and turrets, and 75mm thick armor on the nose of the tank. It was intended that the weight should be kept under 60 tons. However, this order was given regarding standard cylindrical turreted T-35s, and a second contradicting order was issued requiring conical turrets be manufactured along with the improvements recommended after the testing of T-35A 183-5. There was much confusion at the plant, and a moderate modernization was conducted to the T-35.
All of the hull changes improved the performance of the vehicle. Now mud and other debris could not build up between the skirt and the drive wheel (which in earlier machines lead to failures of the track and drivetrain), and the turret sub-structure contained fewer shot traps.
The nose armor of these tanks was additionally increased from 20 mm to 30 mm, which was considered to be the bare minimum that would stop a 45 mm shell from ranges over 1000 m. The turrets of the tanks were also redesigned. All of the turrets now had armor that was 30 mm thick and angled at a shallow gradient to improve the thickness and increase the chances of a ricochet.

T-35 234-42 was the third conical turreted tank. Notice that the turret rear has a ball mount for a machine gun, and the turret had an antenna.  Source: Francis Pulham Collection

234-42 once again from the same photographer. Notice the redesigned skirts on the tank. Source: Francis Pulham Collection
The first three conical T-35s, chassis numbers ‘234-34’, ‘234-35’ and ‘234-42’ were all issued the old clothesline style antennas. Subsequently, T-35s ‘744-61’ and ‘744-62’ dispensed with this in favor of a whip antenna.

234-42 was lost in the village of Zapytiv. Notice the turret has foot plates for an antenna. The hull was almost identical to that of 196-94 and 196-95.
T-35 ‘744-63’ took changes further, dispensing with the main turret rear machine gun ball mount and introducing the ‘BT’ type hatch on the machine gun turrets and on the main turret for the loader. This hatch is referenced as a ‘BT’ type hatch due to the similarity of it with the conical turreted BT-7 turret hatch.
T-35s ‘744-64’, ‘744-65’, ‘744-66’ and ‘744-67’ were the last four T-35s to be manufactured and were again very different machines to the previous tanks. Firstly, the skirts were re-designed to have square access hatches rather than triangular ones. The turret substructure now had angled sides to better deflect shots and, lastly, the driver’s hatch was changed to the BT type.

The foreground displays a final production T-35. T-35 744-64 was the first last production tank manufactured. Notice the angled smoke generator armor, square access hatches to the skirts, the “BT” style drivers hatch and the solid front idler wheel.  Source: Francis Pulham Collection
The T-35 was canceled, as the concept of multi-turreted tanks had proven to be a failure, however, for propaganda purposes, the T-35 sill held potential.

T-35B – Upgraded engine

In 1936, plans were drawn up to improve the engine of the T-35. Following a series of proposals including a BD-1 (400 hp) and a BD-2 (700 hp), BD-2A diesel engine rated at 600hp was decided for further testing. A single T-35A tank had its engine removed and awaited its replacement with the DB-2A. The new standard was known as the T-35B. However, no testing was done as the engine didn’t arrive and the tank sat idle for a year and a half before having the M-17 reinserted.

Parade life and early deployment

The T-35A tank is one of history’s strangest tanks – often seen crawling across the Soviet inter-war parade squares. This tank grabbed the hearts, souls, and imaginations of the Soviet people and foreign military attachés alike. It was one of the many proud achievements of Soviet industrialization – its image appeared on posters, films, and even medals and awards!
At any one time in the Red Square, up to 20 T-35s were paraded, and made great propaganda tools for the Soviet Union. While not a good fighting tank, they were symbols of the new industrial and military strength that the USSR had gained over the previous decade.
As for combat deployment, the T-35 was first assigned to the 5th Heavy Tank Regiment on the 12th of December 1935 when the regiment was reorganised into the 5th Independent Heavy Tank Brigade. In 1938, after the summer maneuvers, the brigade was transferred to the Kiev Special Military District where it was renamed the 14th Heavy Tank Brigade.
Forty-eight of the tanks were later transferred to the 8th Mechanized Corps, two were sent to the Moscow Military District and six were sent to the 2nd Saratov Tank School. In June 1941, on the eve of Operation Barbarossa, five tanks were going through capital repairs, i.e. they were being stripped of old or obsolete parts, to be replaced with fresh or modern parts, back in Kharkov. This is how the stage was set on the eve of what would become known in Russia as the Great Patriotic War.

Deployment in World War Two

The 48 T-35s that were in the 8th Mechanized Corps were deployed in the 67th and 68th Tank Regiments, of the 34th Tank Division. These tanks were deployed at their depots west of Lvov, with the 67th Tank Regiment deployed in the village of Gorodok, 20 km west of Lvov, while the 68th Tank Regiment was deployed at Sadowa Wisnia, 30 km west of Lvov.
One T-35 is listed as being present at the Poligon scrap yard ready for disposal, a second T-35 was in Moscow. Four T-35s are known to have been in Kharkov, and a fifth is unaccounted for. The remaining 6 were at Saratov.
After the German invasion on the 22nd of June 1941, all of the 34th Tank Divisions T-35s were lost between the 24th of June and the 5th of July. Some did fight, like at the Battle of Verba, however, most broke down.
A detailed examination of the T-35A in this period can be found in the book ‘Fallen Giants: The Combat Debut of the T-35A Tank’ by Francis Pulham.

German designations

Until this point, this article has used the Soviet designations for this heavy tank.
The Germans were well aware of the T-35A, and had some intelligence on it before the invasion. A German intelligence bulletin uses the T-35A designation for one of the vehicles that they identified, however, the shape is wrong. They picture a conical turret T-35 with no sub-turrets and a 45 mm gun mounted centrally in the forward hull.
The German document also identifies the SMK two-turreted heavy tank as the T-35C. While the T-35A and SMK were not related, given the mistake the Germans made about the T-35A, it is easy to understand the error.
Some online sources (including our previous article on the T-35) use the T-35B designation for the conical turret T-35A. There are no original sources known to us at this point that verify that the Germans used this designation for this variant. However, given that the Germans used the T-35A and T-35C designations, this seems plausible.
References

Sources

Fallen Giants: The Combat Debut of the T-35A Tank, Francis Pulham
Land Battleship T-35, Maxim Kolomiets
T35incombat.narod.ru, Sergey Lotarev
Aviarmor.net
Tank Archives on German ID of Soviet tanks
The original Germand Intelligence Bulletin

T-35A specifications

Dimensions 9.72 x 3.2 x 3.43
Total weight, battle ready 54 tons
Crew 9
Propulsion M-17 L Aero engine
Armament 76.2mm KT-28
2x 45mm K-20
6/7x 7.62mm DT-29 machine gun
For information about abbreviations check the Lexical Index

tanks posters - Soviet Armour 1941
The T-35A is featured on our Soviet Tanks in June 1941 (Operation Barbarossa) poster! Buy it on Pixels.com!

Combat Debut T35A
Fallen Giants: The Combat Debut of the T-35A Tank

By Francis Pulham

The Soviet T-35A is the only five-turreted tank in history to enter production. With a long and proud service history on Soviet parade grounds, the T-35A was forced to adapt to the modern battlefield when the Second World War broke out. Outclassed and outdated, the T-35A tried to hold its own against the German invaders to no avail. For the first time, actual battlefield photographs have been cross-referenced with maps and documents to bring about the most complete look at the T-35A in the Second World War to date.

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Categories
WWII Soviet Heavy Tanks

KV-85

Soviet Union Soviet Union (1943) Heavy tank – 148 built

The stopgap

By the mid-war, the KV-1 could be considered outdated. Its 76 mm (3 in) gun was not as effective as it was in the early war. The Soviet Union needed a new heavy tank comparable to the later models of the Panzer IV or the Tiger. In 1943, Kotin’s famous technical bureau was split in two – one half was to work on a KV based heavy tank stopgap, and the other was to work on the KV-13 project. The team had already worked tirelessly on the KV-1S that, whilst produced in large numbers, was largely hated by tank crews and officers because it attempted to be as fast as the T-34, but have armor as strong as the KV-1, something that was impossible. The typical Soviet heavy tank certainly needed a new gun, and the KV-13 was to be the answer to this, but a stopgap was needed in the meantime.
A KV-85 showing off its 85mm gun
A KV-85 showing off its 85 mm (3.35 in) gun.

Design process

Whilst many self-propelled guns with higher caliber guns developed at this time (such as the SU-85) were being produced in large numbers, there was long standing work on replacing the aging KV-1. By 1943, there were 21 heavy tank designs that had been created, but they all almost faced cancellation from Stalin because of the scathing reports produced about the KV-1’s inadequate gun and poor mobility, which cost the Red Army dearly. The KV-1S made matters worse because it was a vastly substandard tank that tried to balance two opposing traits – armor and speed. Despite reports from experienced commanders such as General P.A. Romistrov, Stalin did not cancel all heavy tank production. This was thanks to lobbying from the NKTP (People’s Commissariat of the Tank Industry of the USSR), and the need to combat new German heavy and medium tanks, which was becoming more and more evident as the war progressed.
The need to hasten the deployment of heavy tanks led Kotin to divide his TsKB-2 bureau in two. The first team chose to improve the stopgap KV-1S, whereas the second team began work on the new KV-13 headed by N.V. Tseits. Tseits’ vehicle would later develop into the IS-85, a much better balance between speed and armor.
The original KV-85 design was very different to the one eventually chosen. This was the KV-85G – a slightly modified KV-1S with an 85 mm (3.35 in) S-53 gun jammed in a KV-1S cast turret. It appears that only one prototype was made and was deemed unsatisfactory. This is almost certainly due to the lack of space for the crew and gun. Fortunately, the IS-85 turret was available by this time, but the IS chassis was not. Due to long, technical delays in IS-85 production, along with urgent requests for more heavy tanks with an even heavier armament, a new tank was made by taking a further modified KV-1S chassis and sticking an IS-85 turret on top. At least two other prototype vehicles using different 85 mm experimental guns (including the D-5T and a modified ZiS-5 gun, now 85 mm instead of 76 mm/3 in) were put into comparative tests with the new KV-85 (with IS-85 turret). The KV-85G design had already been rejected because of a lack of internal turret space. The KV-85 with IS-85 turret was deemed the most suitable for production.
On August 8th, shortly after these trials, the KV-85 was accepted for service by the State Defense Committee, and Resolution 3891 led to 148 KV-85s being produced as a stopgap from September to December at Chelyabinsk. The fifth crew member (the radio operator) was no longer needed because of demands for larger ammunition racks, containing 70 rounds, as well as the size of the gun breech.
Technical drawing of a KV-85
Technical drawing of a KV-85.
The KV-85 had the same engine as its predecessors and weighed 46 tons, with armor thickness of 60 mm/2.36 in (hull), 75 mm/2.95 in (frontal glacis), to 100-110 mm/3.94-4.33 in (turret front, sides and rear). Top speed was around 40 km/h (29 mph) and range 250 km (155 mi). The D-5T gun was a shorter derivative of the original 85 mm (3.35 in) AA gun (792 m/s or 2,598 ft/s muzzle velocity) and was considered an absolute killer. However, it was much cheaper to make, and a lot less technically impressive.
The KV-85G prototype. It is distinguishable as it has a hull DT visible and no enlarged commander's viewport, as seen on the IS-85 turret
The KV-85G prototype. It is distinguishable as it has a hull DT visible and no enlarged commander’s viewport, as seen on the IS-85 turret.

A KV-122 is inspected by senior Soviet officers in 1943, note the shorter gun and more distinguishable double-baffle muzzle-brakeA KV-122 is inspected by senior Soviet officers in 1943, note the shorter gun and more distinguishable double-baffle muzzle-brake
A KV-122 with the S-41 howitzer is inspected by senior Soviet officers in 1943, note the shorter gun and more distinguishable double-baffle muzzle-brake.

KV-85 variants

-Only 148 of this promising intermediate model were built before the IS-1 was introduced. It led to four variants.
-The KV-85G was the early competitor, which almost entered production, as mentioned earlier. It was simply a KV-1S with an 85 mm gun.
-The KV-122 (1943), KV-100 (1944) and KV-122 (Object 239) (1944) were all prototype derivatives armed with a short 122 mm (4.8 in) howitzer (for indirect fire support), a long 100 mm (3.94 in), and a 122 mm (4.8 in) built and tested in 1943-44. They were never accepted into mass production, but they served as test-beds for the IS-2, which would go on to use the long 122 mm gun. Testing weapons for future tanks on similar chassis that were already available was common practice with Soviet tank designs, and certainly sped up the IS-2 design process.
A sideview of the KV-85. Here, the shape of the KV-1S hull is clear, but the IS-85 turret is even more obvious with its unique rear DT mount and commander's viewport
A sideview of the KV-85. Here, the shape of the KV-1S hull is clear, but the IS-85 turret is even more obvious with its unique rear DT mount and commander’s viewport.

In action

Combat of the few KV-85s was both limited and mixed. On paper, a KV tank with the infamous D-5T gun (as used on the SU-85 tank destroyer and to be used on the iconic T-34/85) sounds like a horrific opponent for the Wehrmacht, but this was not the reality of war. Whilst the larger gun was generally met well, the overall combat effectiveness of the tank was not, mostly due to the chassis. It was simply unreliable, the armor was still poor, and even despite some adjustments, it could not consistently withstand shells of a caliber of 75 mm (2.95 in) or greater.
This is particularly important, as the KV-85 was used as a breakthrough tank, and the Wehrmacht was now fielding high caliber guns to counter the Red Army’s previously near-invulnerable tanks. In one engagement in the Ukraine in November, 1943, the 34th Guards Heavy Regiment was repulsed with the loss of one third of its KV-85s by fire from Panzer IVs and Marder IIs. However, it could be argued that tactical factors influenced the level of losses faced by the Regiment and it is worth noting that a German counterattack was beaten off the next day with no Soviet casualties.

It was still noted that better protection was needed against even long-range enemy fire. It is evident that the tank itself simply did not pass the brutal quality control of war in 1943, but one must remember that the KV-85 was only a mere stop-gap to fill in for the slow development of the IS-1. Overall, the KV-85 was built in too few numbers to influence the war, but it certainly proved the need for IS tank production. Both the IS-1 and KV-85 were put up against the Tiger tank, but it was the IS-1 which proved itself more capable because of its modern chassis. IS-1/IS-85 production began the following year.
A KV-122 prototype. Notice how similar it looked to the IS-2MKV-1S in the Kubinka tank museumRear view of a KV-85

An article by Wilkerrs

Links

The KV-1 (generic) on Wikipedia

KV-85 specifications

Dimensions (L-w-h) 8.49 x 3.25 x 2.87 m (27.85 x 10.66 x 9.42 ft)
Total weight, battle ready 50.7 tons (111,800 lbs)
Crew 4 (commander, driver, gunner, loader)
Propulsion 12 cyl, 45 l, Mikulin, 600 hp V-2
Speed (road/off-road) 35 km/h (21.7 mph)
Range 160 km (100 mi)
Armament 85 mm (3.34 in) D-5T gun (60 rounds)
3 x DT 7.62 mm (0.3 in) machine-guns
Armor 20 to 100 mm (0.79-3.4 in)
Total production 148

ww2 soviet armour
ww2 Soviet Tanks Poster

KV-85, unknown unit of the Guards, Eastern Prussia, December 1943.
KV-85, unknown unit of the Guards, Eastern Prussia, December 1943.
KV-85, unknown unit, eastern Prussia, fall 1944.
KV-85, unknown unit, eastern Prussia, fall 1944.
KV-85 of the 1452nd SP gun regiment, Crimea, April 1944.
KV-85 of the 1452nd SP gun regiment, Crimea, April 1944.
Categories
WWII Soviet Heavy Tanks

KV-1

Soviet Union (1939) Heavy Tank – 5,219 built

Heavy tank and “deep battle” concepts in the USSR

The concept of “deep battle”, which contained the doctrinal use of the Soviet heavy tank, was first theorized during the late twenties, then refined and eventually adopted by the Red Army Field Regulations in 1936. The tactical deep battle doctrine advocated for fast battle tanks (BT series and T-26), reconnaissance types (T-27, T-37A, T-38 tanks and tankettes) and medium or heavy penetration tanks (“Tyazholy”). The latter were also also called “siege tanks” and had to be able to resist most AT gun calibers, either deployed by enemy infantry or other tanks, and to destroy them as well. They were to be placed on key tactical positions to drag and concentrate enemy fire, or destroy enemy fortified positions while assisting infantry. Protection was therefore given priority over mobility.
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T-35, T-100 and SMK

After the T-28, which was considered a medium, infantry tank design, the T-35 became the first of these heavy tanks to enter service with the USSR. This was a true monster, influenced by the multi-turreted fad which came from Great Britain, but was quite complicated and unsatisfactory in operations.
A new 1937 specification gave birth to the two T-100s and the unique SMK prototype, showing a new arrangement of firepower, with tandem turrets. All three were tested in operations in Finland during the “Winter War” (September-December 1939). They proved resistant, but showed very poor reliability and mobility. They were also costly, over-complicated and difficult to maintain. Another prototype however, the KV, had been drawn by the same team which designed the SMK, as a single-turreted variant. During these operations, the two KV prototypes outperformed the others and the type was subsequently approved for a 50-unit pre-series under the name of KV-1.

Origin of the Kliment Voroshilov tank

The TsKB-2 design bureau responsible for the SMK, through chief engineer Zh. Kotin, designed at first an all-welded hull with cast turret and large parts, with wide, reinforced tracks and a torsion-bar suspension. Alongside the SMK, the KV, named after People’s Defense Commissioner and political statesman Kliment Voroshilov, was essentially a single-turret variant, the weight saved being utilized for extra frontal and side protection, without any sacrifice to mobility. Initially not meant for production, the KV was given direct approval from Stalin himself.
KV-1 model 1942, Finnish capture at Parola museum
This model should have been named “Kotin-Stalin” (KS-1) instead. A wooden mockup was ready in April 1939, and first presentation to the general staff in September. Both prototypes were tested at the Kubinka proving grounds near Moscow, and immediately after in real combat conditions in Finland. The two KV prototypes and the first 50 preseries KV-1s were virtually identical, only differing by some redesigned parts for easier production. The hull, transmission, optics and torsion bar suspension were all borrowed from the SMK. Production was first assumed by Kirov Factory, ChTZ, and the first 50 were part of the “model 1939”, but were delivered in March 1940.

Design of the KV-1

KV-1 model 1939The model 1939 was nearing 45 tons in weight, with a long hull (6.75 m/22.14 ft), relatively narrow if not for the very large tracks. The generous mudguards above gave exceptional room for storage. However, as no transmission was able to cope with such mass, the designers found an expedient, giving both prototypes and the SMK an old but sturdy Caterpillar system, which proved tricky, even unreliable in operations. The driver sat in the middle and the radio operator/machine gunner sat on the left, the three other crew members being located in and below the turret.
They had poor visibility, with narrow vision slits. The driver had his frontal slit made of poor quality laminated glass, which proved blurred most of the time and his vision periscope had limited traverse. The commander (which also the loader) had two turret periscopes. The wheel train comprised front idler wheels and rear drive sprockets (like on the T-28) and a set of 6 twin roadwheel bogies, each sprung to an independent torsion-bar apparatus. There were also, due to the weight of the tracks, three large and thick return rollers. These large tracks had excellent traction on soft ground (snow and mud). The protection, reaching 90 mm (3.54 in) on the front (glacis and turret), was unrivaled for the time, if not for rare equivalents like the British Matilda II (80 mm/3.15 in) and the French B1 bis (70 mm/2.76 in), but way ahead of any German tank.
Destroyed KV-1 s ekranami model 1940 near Olonets, September 1941

The KV-1 model 1939 and 1940

At first, the 76.2 mm (3 in) F-32 was chosen as main armament, but due to delays in production, the first 50 preseries models and all remaining model 1939s were equipped with a medium-velocity “short” barrel L-11 of the same caliber, fitted with a recognizable recuperator above the barrel. The F-32 was able to fire AP (F-342 rounds) and HE shells. The BR-3502 AP rounds were capable of reaching 612 m/sec (2007 ft/s), giving them a 66 mm (2.6 in) armor-piercing capacity at 500 m (1640 ft). Secondary armament comprised a coaxial DT 7.62 mm (0.3 in) machine gun, another in a rear turret ballmount, another mounted in a hull ballmount and an extra AA mount on the model 1942.
Destroyed KV-1 model 1941 destroyed near Voronezh in 1942 - Credits: Bundesarchiv
The engine was the 12-cylinder diesel model V-1, giving 600 [email protected] rpm (450 kW), and then V2 (model 1940), fed with a 615 liters capacity storage. In all, 141 model 1939s were delivered, followed by 243 to 250 of the model 1940. Most were delivered during 1940 and early 1941. The model 1940 (also called KV-1A) was equipped with the longer F-32 gun and a new mantlet. When production began the German invasion was on its way. The Kirov factory was later moved at Chelyabinsk during the winter of 1941, and a new model was designed.

The KV-1E or Ekranami

Before the model 1941 production started and the factory was relocated near the Urals, many KV-1s were taken over for an expedient armor improvement. These versions, called “Ekranami” (“with screens”), received tailored 20 mm (0.79 in) soft steel plates, bolted-on (with huge bolts), as appliqué to the turret, frontal glacis and sides of the hull. These KV-1Es were mostly surviving units of the earlier model 1939, which were up-gunned with the F-32 in the same process, and later 1940 and 1941 models, sometimes damaged and recovered tanks.
Exact number of this variant remains mysterious. Some sources speaks of 150 to 200+ units being converted in 1942. This was a response to new German tactics, hastily devised on the spot to counter the impregnable KV-1. The introduction of the new Pak-38 and Pak-40 AT guns and later some airborne weapons, like the MK 101 fielded by the Henschel 129 ground attack aircraft, urged this conversion. Total armor thickness was around 110-120 mm (4.33-4.72 in), making the KV-1 once again nearly impregnable.

The KV-1B model 1941

The model 1941 was designed and produced at Chelyabinsk. A model F-34 gun was fitted. This was the same gun installed on most T-34/76s. As a response to the field-expedient appliqué armor, the hull, sides and turret were protected by an additional 25 to 35 mm (0.98-1.38 in) of extra armor, and the turret was now cast instead of welded. This version also introduced many simplifications for mass-production. However, it was slow to arrive at the front, and the first model 1941 became operational in early to mid-1942 at best.
The late production tanks received an even longer barreled gun, the ZiS-5 76.2 mm (3 in). This increased somewhat its penetrating performances. However, by the fall of 1942, new German tanks, like the Panzer IV F2 and 50 mm (1.97 in) armed late Panzer IIIs, outranged the KV-1 while still being able to pierce it. This version however still retained the original V12 diesel, and was decidedly underpowered. Speed was reduced further and this proved an issue in combined operations alongside the T-34. Production of this model was around 1200 units, according to the factory log.

The KV-1C (model 1942)

The model 1942 was essentially a late up-armored model (10-15 mm/0.39-0.59 in), either with a cast or welded turret. This was also the biggest production of the type, with around 1700 units. They were also all armed with the 76.2 mm (3 in) ZiS-5 and sometimes equipped with AA mounts. However, criticism about the series prompted parallel studies to improve the KV-1 as a whole. These reports stated that its only asset was excellent protection, however, speed and agility were poor, the transmission proved often prone to break downs, the suspensions, crumbling under the raising weight also showed critical stress failures, as well as the overwhelmed engine (the V12 V-2K, a modified version of the T-34 diesel).
Final weight of this 1942 version was around 48 tons. Only the German Tiger was equivalent in weight, but was equipped with better optics and a gun which far outclassed anything on the field. This led to the two last improved versions of the type, before the production really stopped in favor of better designs.

The KV-1S, the fast one

The main criticism about the weight imposed a completely revised version with somewhat “downgraded armor”, in order to regain some agility. In fact, this was not an equal sacrifice. Some vital parts, determined after carefully studied statistics about tank loss reports, were still well protected, while sacrificing others. This was a near “all-or-nothing” protection, which also came with special tactical maneuver instructions in order to reduce the exposure of these “weak spots” to the enemy. However, the engine was untouched.
Another improvement concerned the cast turret, which was redesigned completely, lower, smaller, with slightly sloped sides and, most importantly for the first time, fitted with a real commander cupola bearing all-around vision blocks, which in turn greatly improved the overall vision and efficiency of the commander.
However, this KV-1S (for “Skorostnoy” – “fast”), was still much more expensive than the T-34/76, for the relative same performances. By late 1943, there were concerns about the cancellation of this new version, which occurred after 1370 had been delivered, from autumn 1942 to the fall of 1943. Total weight was 42 tons, and protection ranged from 30 to 75 mm (1.18-2.95 in). The main armament, a 76.2 mm (3 in) L42, was fed by 114 rounds, and the three DT machine-guns by 3000 rounds.

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The KV-85, blueprint for the IS-1

Another strong criticism about the KV-1 concerned its main armament, which was the same as the medium main tank of the Red Army, the T-34. But the KV-1 was more expensive and with far less mobility. A better gun could have effectively saved the KV-1, making something comparable to the last version of the Panzer IV or the Tiger. By 1943, Lieutenant-Colonel Kotin’s technical bureau was split in two, a part being affected to studying a new stopgap heavy tank based on the KV-1, waiting for its replacement to come. The team naturally chose the improved KV-1S, but increased the armor protection in vital parts to 110 mm (4.3 in), and widened slightly the hull to accommodate a larger turret and gun, the 85 mm (3.35 in) D-5T which was also chosen to equip the IS-1.
KV-1 model 1942 with welded turret, on display at the Leningrad diorama museum near Kirovsk- Credits: Wikipedia CC licence
Due to this interim position, the KV-85 was only produced in limited quantity by the beginning of 1943. 143 units of this ultimate version will be delivered until the production stopped for good. The KV-85 had the same engine as its predecessors and was 46 tons strong, with thickness of 60 mm/2.36 in (hull), 75 mm/2.95 in (frontal glacis), to 100-110 mm/3.94-4.33 in (turret front, sides and rear). Max speed was around 40 km/h (29 mph) and range 250 km (155 mi). The DT-5 gun was a shorter derivative of the original 85 mm (3.35 in) AA gun (792 m/s or 2,598 ft/s muzzle velocity).

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The KV-1 in action (1941-44)

As the production began in 1940, at a slow pace, only a handful of KV-1s were operational when Operation Barbarossa began. Usual figures are about 530 operational into twenty-nine mechanized corps, alongside all available T-34s (1590 tanks in all). They were about a third KV-1s for each of these units. They first met the Wehrmacht on June, 23, 1941, the second day of the invasion. More precisely, it was at the Battle of Raseiniai, when the Soviet 2nd Tank Division from the 3rd Mechanized Corps clashed with the 6th Panzer Division near Skaudvilė.
They encountered little resistance from forces composed mainly of Pak-36 and 38 AT guns and Panzer 35(t) light tanks. The next day, a single KV-1 successfully blocked any advance of some elements of the 6th Panzer Division for 24 hours, before running out of ammunition and retiring. It was hit by dozens of different calibers, but remained unscathed.
At Krasnogvardeysk (Gatchina, near Leningrad) on August 14, 1941, a small unit of 5 well-hidden and entrenched KV-1s, plus two in reserve, with twice the usual ammunition supply, including a majority of AP shells, were skillfully placed around the single road bordering a swamp. This unit, commanded by Lieutenant Zinoviy Kolobanov, destroyed some 43 German tanks from German 8th PzD during a single half-hour action. Kolobanov was later awarded the Order of Lenin and made Hero of the USSR.
KV-2 model 1940
The KV-2, heavy howitzer version. This was a generally unsuccessful variant. The turret was easy to spot, top-heavy, making the tank fairly unstable. Plus, the howitzer blast provoked excessive vibrations for the engine and transmission.
Many alarming reports all pointed in the same direction. These “new” Russian tanks were nearly unstoppable. In fact, their existence had been one of the biggest blunders of German intelligence prior to the invasion.
Facing these, the Germans had a total of 3266 tanks, but only 1146 Panzer IIIs and IVs armed with 50 mm (1.97 in) or 75 mm (2.95 in) guns, barely able to penetrate the armor (and only on weak spots) of the two models (T-34 and KV-1). Most of the KV-1s were concentrated in 6th, 4th, 8th and 15th Mechanized Corps during the summer, and all but one were sent in Ukraine. They suffered heavy losses however, despite being usually bypassed by the Panzers, left to the air support, field artillery and 88 mm (3.46 in) guns, or special antitank squads using shaped charge grenades.
Many also broke down, ran low on fuel or were abandoned due to the confusion of the first two weeks of Barbarossa. The total losses were far greater anyway to those related by the German reports, and by the autumn 1941, few were still extant. Anyway, the impression left by the KV-1 (as well as the T-34, which was faster and more numerous), from the simple soldiers to the general staff, was huge. It triggered an unprecedented Panzerkommision on 20 November 1941, which studied remains of both tanks on the field. The T-34 is notable to have inspired the development of the sloped-armored Panther.
After a ruthless relocation in dire conditions of the entire Russian war industry next to the Ural mountains, production of the KV-1 was resumed. Two models were produced alongside, the “cast turret” and “welded turret”, which otherwise were generally similar, bearing the same F32 gun. For easier production the model 1942 was a near-repeat of the former, although up-armored. Older models were massed together for the counter-offensive of Moscow in January 1942, but the Germans were now better prepared, although still fielding the same Panzer IIIs and IVs.
Among these, many were upgraded as Ekranami versions, receiving thick appliqué bolted plates. This was a response to some new German weapons, like the shaped charges and airborne AT guns. Throughout 1942, the KV-1s performed well, although combined operations with the T-34 were problematic due to the speed difference between them. Too often, the KV-1s were relegated as support rearguards and committed only when encountering a fierce resistance.
These tanks fought during nearly all major engagements of 1942-43, including the large counter-offensive of Stalingrad, in January 1943. By then, Soviet industry has produced enough T-34 to literally overwhelm the KV-1 in number (the latter being much costlier). Growing discontent about the type revolved usually around the same issues. It was too slow (easier to spot and target), prone to transmission failures, simply too heavy for many bridges and at the same time not equipped to ford deep rivers, and lacking range against the late 1942 German AT units and rearmed Panzer IVs. Late versions, even heavier, lost what was left of its former maneuverability, while at the same time still not being better armed than the T-34.
Further heavy losses at Kursk proved they definitely found their match in the new German tanks generation. This situation was found acceptable for the general staff however, which considered them as breakthrough tanks, operating against infantry and fortified lines of defenses, firing HE shells at relatively short range and only carried a few AP rounds for occasional encounters. They kept this tactical specialization until late 1943, before being superseded by the IS-2. By 1944, the existing KV-1s were mostly of the late KV-85 type. Their heavy armor still proved effective while dealing with well-prepared German defenses. However, by the end of 1944, they were seen as obsolete. There is no evidence that any KV-1 or KV-85 took part in the battle of Berlin.

Derivatives of the KV-1

The KV-2 heavy artillery tank

When encountering difficulties on the heavily fortified Mannerheim line during the Winter War in Finland, the general staff demanded a specially equipped version fitted with a heavy howitzer, intended to deal with concrete bunkers, in support of the regular KV-1 units. But instead of choosing a more pragmatic solution of a traditional SPG, the Soviet engineers tried to get the best of both worlds in a hurry, while using the same turret ring to accommodate a fully traversable, redesigned turret to house the gargantuan howitzer. This gave the KV-2 an unmistakable profile, with its huge, towering turret, which was only accessible by a ladder. An obvious target which was also top heavy, compromising the lateral stability of the tank while crossing a sloped terrain. All these deficiencies were taken in account when the factory was relocated in the new “Tankograd” complex at the steps of the Ural. The production was no longer maintained. Only 334 were built in all from late 1939 to mid-1941.

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The KV-8 flame-thrower

The KV-1 was also chosen to be used as platform for the new ATO-41 flame-thrower. The gun mantlet accommodated the flamethrower tube, a coaxial DT machine-gun and, replacing the former ZiS-5 gun, a 45 mm (1.77 in) QF model 1932 in disguise, housed inside a 76 mm (3 in) tube. The gun was standard issue on the BT series and the T-26, and had good penetration power against 20-25 mm (0.79-0.98 in) of armor. 45 units were converted using KV-1B hulls (model 1941), and later on, 25 more based on the upgraded KV-1S. Two prototypes of the next version (KV-1M) and a few experimental units with the flame-thrower was relocated in the hull were also built and tested in combat.

The SU-152 SPG

Probably the most distinctive Soviet SPG of the war, the SU-152 renewed the idea formerly tried, although unsuccessfully, by the KV-2. Developed relatively late in the war, for the upcoming Operation Uranus (the great Stalingrad counter-offensive), this “pillbox killer” was a more sound (and simpler) design. The long howitzer was simply relocated into the hull, making it easier to manufacture, more stable and more difficult to hit. It was based on the KV-1S and arrived in time for Kursk, proving also an excellent improvised anti-tank machine, soon nicknamed “the beast killer”. Later on it was associated to the great offensives of 1944-45 and was widely used (and photographed) during the battle of Berlin. Around 700 were built in all, including the late ISU-152 based on the improved IS-1 series chassis.

Prototypes

Heavy tanks
The T-150, KV-220 and KV-220-2 were early 1942 projects with 700 to 850 bhp diesels, armed with 76 mm (3 in) to 85 mm (3.35 in) guns. One KV-13 was buit, being a new generation “universal” medium tank drawn in late 1942.
Super-heavy tanks
The KV-1 chassis served as a basis for many tests, starting with the KV-3, a single prototype, which had an extra pair of rollers, a lengthened hull to accommodate a new 850 hp V-2SN engine, a hull protected (at the front) by 130 mm (5.12 in) of armor and a 107 mm (4.21 in) ZiS-6 gun. It was shipped to the front with a KV-1 turret and destroyed in combat by German field artillery in 1941. The KV-4 and KV-5 were even larger version, but stayed as paper projects. These super-heavy tanks would have been up to 150 tons. 20 different projects were proposed, but all cancelled by 1943 in favor of the IS-1.
SPGs
The experimental KV-7 was a self propelled-gun with three guns (one 76 and two 45 mm/3-1.77 in). The KV-9 was a battle-tested 122 mm (4.8 in) SPG prototype, which was an early forerunner for the SU-122 series. The U-18 and U-19 existed only as a mockups or on paper. The KV-10 (or KV-1K) was fitted with four 132 mm (5.2 in) M-13 rockets launchers installed on the large mud-guards, but remained a prototype.

KV-85 variants
Only 148 of this promising intermediate model were built, before the IS-1 was introduced. It led anyway to four variants. The KV-85G was a competitor, also armed with a 85 mm (3.35 in) S-31 cannon, but the KV-85 was chosen instead. The KV-100 and 122 were prototype derivatives armed with a long 100 mm (3.94 in) or a 122 mm (4.8 in) gun, built and tested in 1943-44. They served as testbeds for the IS-2.

Legacy of the Kliment Voroshilov heavy tank

Despite being plagued by problems due to a rushed conception, the formidable reputation of the KV-1 came first from a legendary sturdiness, which was paid in return by a record weight. It paved the way for the next generation of Soviet heavy tanks which took everything from it. Despite the name, their new turret and heavier guns, the IS (Iosif Stalin) series were still KV-1s in disguise. They borrowed everything from the chassis to the tracks, road wheels, suspensions, diesel engine, transmission and most of the equipment.
And if the IS-3 (which was never to fire a shot before the capitulation) had a different look, with a brand new, entirely redesigned sloped hull and characteristic rounded, flat turret of the Soviet postwar design, it remained essentially a KV-1 inside. The KV-13 design tried briefly to reunite the T-34 and the KV-1 in a single package, but failed. However, its legacy was to endure in the very last Soviet heavy tank design, the T-10 (1958), after a long series from the IS-4 to the IS-7. They were to bring support to the more agile T-54/55 during the Cold War. But the heavy type had to definitely disappear in favor of the “universal” type, the main battle tank.

KV-1B specifications

Dimensions (L-w-h) 5.8 x 4.2 x 2.32 m (19.2×13.78×7.61 ft)
Total weight, battle ready 45 tonnes
Crew 4 (commander, driver, 2 gunners)
Propulsion V12 diesel V2, 600 bhp (400 kW)
Maximum Speed 38 km/h (26 mph)
Range (road/off road) 200 km (140 mi)
Armament 76.2 mm (3 in) L32
3x DT 7.62 mm (0.3 in) machine-guns
Armor 30 to 100 mm (1.18-3.93 in)
Total production 5819

Links and references

The KV-1 on Wikipedia
ww2 soviet armour
All ww2 Soviet Tanks Posters
The first KV-1 prototype in Finland with the 91st Tank Battalion of the 20th Heavy Tank Brigade, near Suma, 17-19 December 1939, alongside two T-100s and one SMK
The first KV-1 prototype in Finland with the 91st Tank Battalion of the 20th Heavy Tank Brigade, near Suma, 17-19 December 1939, alongside two T-100s and one SMK.
KV-1 model 1939 with welded turret. Central front, summer 1941.
KV-1 model 1939 with welded turret. Central front, summer 1941.
KV-1 model 1940, Central front, autumn 1940. Slogan For Russia.
KV-1 model 1940, Central front, autumn 1940. Slogan “For Russia”.
KV-1 model 1940 of the Moscow heavy tactical reserve, winter 1941/42. Slogan: For Stalin
KV-1 model 1940 of the Moscow heavy tactical reserve, winter 1941/42. Slogan: “For Stalin”.
KV-1 model 1941 with a complex Finnish camouflage pattern, winter 1941/42. Also notice the new spoked wheels.
KV-1 model 1941 with a complex “Finnish” camouflage pattern, winter 1941/42. Also notice the new spoked wheels.
KV-1 model 1940 s ekranami (up-armored). Unknown reserve front unit, summer 1942.
KV-1 model 1940 s ekranami (up-armored). Unknown reserve front unit, summer 1942.
KV-1 model 1941 s ekranami (up-armored), unknown unit, Leningrad sector, winter 1942.
KV-1 model 1941 s ekranami (up-armored), unknown unit, Leningrad sector, winter 1942.
KV-1B (model 1941), 124th Guard Tank Brigade, part of the 24th Tank Division, operating near Leningrad.
KV-1B (model 1941), 124th Guard Tank Brigade, part of the 24th Tank Division, operating near Leningrad.
KV-1B, Leningrad sector, winter 1941/42. The winter camouflage is another variation with omitted spots to create an alternative pattern.
KV-1B, Leningrad sector, winter 1941/42. The winter camouflage is another variation with omitted spots to create an alternative pattern.
KV-1 model 1941, late production, 53rd Army of the Transcaucasian Front, Anglo-Soviet invasion of Iran, September 1941.
KV-1 model 1941, late production, 53rd Army of the Transcaucasian Front, Anglo-Soviet invasion of Iran, September 1941.
KV-1 model 1941/42 with a partially welded turret and the new ZiS-5 long barrel gun. Unknown unit, Central Front, autumn 1942.
KV-1 model 1941/42 with a partially welded turret and the new ZiS-5 long barrel gun. Unknown unit, Central Front, autumn 1942.
KV-1 model 1942 with a fully cast turret. Unknown unit, Southern Front, summer 1942. Slogan October Revolution
KV-1 model 1942 with a fully cast turret. Unknown unit, Southern Front, summer 1942. Slogan “October Revolution”
Artist's impression of a KV-1 model 1942 (fully cast turret) Kutuzov in white washable paint livery, unknown unit, Northern front, winter 1942/43. Many Soviet tanks were named after Soviet generals and heroes.
Artist’s impression of a KV-1 model 1942 (fully cast turret) “Kutuzov” in white washable paint livery, unknown unit, Northern front, winter 1942/43. Many Soviet tanks were named after Soviet generals and heroes.
KV-1 model 1942, unknown unit, Finnish front, March 1942. Notice the DT 7.62 mm (0.3 in) machine-gun AA mount and the faded white paint.
KV-1 model 1942, unknown unit, Finnish front, March 1942. Notice the DT 7.62 mm (0.3 in) machine-gun AA mount and the faded white paint.
KV-1 model 1942 (late production), unknown unit, Southern front, spring 1942.
KV-1 model 1942 (late production), unknown unit, Southern front, spring 1942.
KV-1 model 1942 (late production), Central front, early 1943. Slogan Death for death. The original factory green was modified due the passing of one winter and burning gasoline from an explosion and other chemicals. Fighting inside factories was not unusual in many street battles.
KV-1 model 1942 (late production), Central front, early 1943. Slogan “Death for death”. The original factory green was modified due the passing of one winter and burning gasoline from an explosion and other chemicals. Fighting inside factories was not unusual in many street battles.


Flamethrower versions

KV-8 (flame-thrower version), 503rd Independent Armored Battalion, Volhovsky sector, summer 1942.
KV-8 (flame-thrower version), 503rd Independent Armored Battalion, Volhovsky sector, summer 1942.


Captured KVs (Beutepanzers)

PzkPfw KV-1B 753(r), SS Panzer Regiment of the 2nd SS Panzergrenadier Division
PzkPfw KV-1B 753(r), SS Panzer Regiment of the 2nd SS Panzergrenadier Division “Das Reich”, Group Center, spring 1943. Notice the salmon camouflage over the standard dunkelgrau of captured units.
KV-1C (Model 1942) or PzKpfw KV-IC 753(r), 3rd SS Panzer-Grenadier Division
KV-1C (Model 1942) or PzKpfw KV-IC 753(r), 3rd SS Panzer-Grenadier Division “Totenkopf”, Kharkov, March 1943.
PanzerKampfwagen KV-1B 756(r), 204th Panzer Regiment, 22nd PanzerDivision, Kursk, summer 1943.
PanzerKampfwagen KV-1B 756(r), 204th Panzer Regiment, 22nd PanzerDivision, Kursk, summer 1943.
ww2 soviet armour
ww2 Soviet Tanks Poster

Categories
WWII Soviet Heavy Tanks

IS-2

Soviet Tanks Soviet Union (1943) Heavy tank – 3,854 built

A new standard in hell: The IS-2

As the escalation between German and Russian engineers reached a new point with the introduction on the German side of the Panther and Tiger, and the knowledge that something bigger was brewing, the IS-2 was pressed into introduction as soon as its main armament was ready. With a partly sloped frontal armor, 120 mm (4.72 in) thick and, moreover, a new massive 122 mm (4.8 in) main gun, the new heavy tank seemed to be just the trump card Stalin needed to wash over any armored opposition on the Eastern Front. Or so it seemed on paper. In reality, some shortcuts were taken to meet the expectations. These would prove real issues on the long run, starting with the gun itself, slow to reload and with bulky two-piece naval ammunition.
KV-13 cutaway view
KV-13 prototype cutaway

Precursors: The IS-1 and IS-100

The IS-1 was an improvement over previous designs, combining the hull developed for the KV-13 prototypes with the new three-man KV-85 turret, fielding the new D5-T 85 mm (3.35 in) gun. The only issue with this gun was that the new medium T-34/85, which sported the same gun, was released in the meantime, entering service during the winter 1943/44. So the IS-1 had, like the former KV-1, only slightly better protection, but shorter range and poorer mobility compared to its medium counterpart.
However, the roomy turret could manage heavier and better guns. As early as November and December 1943, tests were performed with a new gun, the 100 mm (3.94 in) BS-3 already tested on the new SU-100 tank-hunter. This resulted in the IS-100, two prototypes which went into trials against the IS-122 armed with the new A19 122 mm (4.8 in) gun. Though the IS-100 was reported to have better armor-piercing qualities, the latter had better all-around performance, and the IS-100 development was terminated.
KV-13 front view
KV-13 prototype front view

The IS-122

The choice of a new 122 mm (4.8 in) gun was studied by Kotin’s team at Zavod Nr.9. As shown at Kursk, the 122 and 152 mm (5.98 in) guns were better suited to take on on the new German tanks, the Tiger, Panther and Elefant. It was obvious that, aside the 85 mm (3.35 in) gun, more suitable for the next evolution of the T-34, a 122 mm would be most recommended to be fitted on the new heavy tank. The adapted field gun A19 model 1937, designed by General A. A. Petrov, had a single chamber muzzle brake, was fitted with a recoil cradle and loading/lifting mechanism from the experimental U-11 and hybridized with a M-30 howitzer mount. Ballistic tests were performed between the A19 and BS-3 in October-November 1943, on a captured Panther.
KV-13 side view
KV-13 prototype side view

This led to the acceptance of the 122 mm (4.8 in) by the HBTU, but also a modification of the muzzle brake with two chambers (“German type”), after almost fatally injuring Marshall Voroshilov during a test in the presence of the Main Defense Commissariat. The A19 still possessed features retained from the original gun, including the cumbersome two-part shell. This had two consequences. A trained crew could only fire two to three rounds a minute, while the ammo supply was limited to only 27 rounds. Nevertheless, the A19 had a better punch despite lower muzzle velocity compared to the 100 mm (3.94 in). It was believed the frontal armor would protect the tank until the target was within a 500 yards (460 m) range, where the heavy round could have its maximum impact. Around 102 to 107 IS-122s were delivered between December 1943 and February 1944, and the name was changed to IS-2.

The IS-2 model 1943

Armor

The first version of the IS-2 (production name) was equipped with the A19 gun, and production started in November 1943 at the Chelyabinsk factory. Initial proposals for the turret included a 152 mm (5.98 in) howitzer, a 50 mm (1.97 in) mortar capable of launching smoke shells or flares and, most importantly, a fully revolving commander cupola also serving a DSHT heavy machine gun. The latter was intended for AA defense and was finally accepted in the definitive production design. The second great innovative figure of the IS-2 was its new frontal armor, still stepped, but uniformly “blended”, with 120 mm (4.72 in)/30° and 60 mm (2.36 in)/72° slope, offering better resistance while still saving weight. Thanks to this, the glacis could now withstand a 88 mm (3.46 in) AP shell at 1000 m (1100 yards). Because of the large recoil mechanism of the gun and a 1800 mm (70.86 in) turret ring radius, the internal space was cramped and only permitted a four-man crew, the commander having to command, order fire and make radio contact.
KV-13 front view
KV-13 prototype front view

Powerplant

The diesel engine was the V2-IC, basically the same already installed in the KV-1, with some antiquated features, but also some improvements. There was an inertial starter with manual and electric drives or compressed air which could be activated from the inside. The electric inertial starter was an auxiliary electric motor giving 0.88 kW. There was a NK-1 high pressure pump with variable speed master RNA-1 and leak proof fuel cells. Air filtering through the fighting compartment was obtained by using the engine to pump the air from inside, and there was a reverse for heating the crew in winter. The engine was given a warming device installed in the transmission unit, in order to start it when it was extremely cold. The engine was fed by three tanks, two into alongside fighting compartment and one at the rear, in the engine compartment unit. Four external tanks with a total capacity of 360 liters could be added as well, not a luxury since the near 50 ton vehicles were well-known “gas-guzzlers”.
KV-13 rear view
KV-13 prototype front view

Drivetrain

The drivetrain was identical to the one of KV-85 and very similar to that of the KV-1, with 6 double cast metal 550 mm (21.65 in) road wheels suspended by robust torsion arms on each side and three return rollers. The front idlers were of the same kind as the roadwheels to ease production, while the large dented rear drive sprockets were also unchanged since the beginning. The track was also consistent with previous models, counting 86 links, 650 mm (25.59 in) wide each. The transmission comprised a multi-disc main clutch dry friction “Ferodo steel”, four-speed dual (8 forward and 2 reverse), but the second reverse gear was only available in theory, as it was never used in reality. There was a two stage planetary rotation mechanism with multi-locking “steel on steel” clutch dry friction and band brake, and two-lane combined board gear.

Production

The bulk of the production started in February 1944, with around 2,252 delivered until the end of the year, perhaps 50% being of the new IS-2 1944 model. There was a subtle difference concerning the nose, between the one manufactured by Chelyabinsk (rounded cast) in August 1944, and the UZTM nose which had a flat lower bow plate. But as soon as they were put into service, alarming reports claimed that the limited ammo provision always meant supply had to be carried by following trucks, and the low rate of fire was almost half that of the T-34/85, while the latter had greater muzzle velocity.
KV-13, 1st prototype
KV-13 prototype front view

A new gun was urgently needed. Plus, other reports showed that even the new armor-piercing shell BR-471 failed to penetrate the frontal armor of a Panther at less than 700 m (765 yards). Only the RP-471 HE rounds had a better chance in jamming the enemy turret, because the tremendous blast torn away the turret ring. Same effects could be devastating on the tracks. However, the situation tended to change in time because of the degrading quality of German steel armor plates, devoid of Manganese, as it was in short supply. The high carbon steel used instead was much more fragile.
The anti-aircraft DSHK heavy-machine gun was introduced on the final production IS-1. Its performances were relatively similar to the cal.50 in terms of penetration, rate of fire and reliability. The massive pintle mount was located just at the rear of the commander cupola, which itself could turn, acting as a ring mount.
IS-1, 85 mm (3.35 in) gun

The IS-2 model 1944

By 1944, a new version of the 122 mm (4.8 in) gun, the D-25T, already tested in January on a single IS-122, was accepted in service to replace the A19. It had a 780-790 m/sec muzzle velocity (2600 ft/sec) and could penetrate 140 mm (5.51 in) of armor at 500 m (550 yards). But, most important, the breech mechanism, although still semi-automatic, was geared to sustain a reduced loading time. The design team also wanted a more protective turret, but the added armor would lead to an unbalanced design, thus forcing the redesign of many other parts of the tank. But since production was paramount the project was cancelled. The problems of internal glacis armor plate releasing fragments when hit was solved thanks to the experts of the CRI-48 tank builders, which developed a new form of armor plates, as well as improved the manufacturing technologies.
The other important innovation was an uniformly sloped frontal glacis plate at angle of 60°, with 100 mm (3.94 in) of armor. According to some sources, 1,150 were built after May 1945 before the series was terminated in favor of the IS-3. The only variant known was a mine roller version deployed by a special Guards Battalion during the later phase of the assault on Berlin. Reliability also increased in time. The first IS-2s from the summer 1944 series were only guaranteed for a 1,000 km (621 mi) run. However, by 1945, the commander of the 1st Belorussian Front reported that “The heavy tanks worked well and exceeded the warranty period by 1.5 to 2 times, both in hours usage and by kilometrage”.
IS-1

The IS-2M

Another version was experimentally built in the summer of 1944. It was a radical departure from the series, with the transmission and fighting compartments relocated to the rear, the engine in the center and driver and radio at the front. The chassis was reworked with a new drivetrain comprising larger doubled roadwheels and no return rollers. In the meantime, new prototypes were conceived, the IS-3, IS-4 and IS-5, which all had design flaws and saw limited production. Consequently, the confidence given to the battle-tested IS-2 by the supreme command of the Red Army was to push an extensive set of postwar modifications, first ratified in 1954 and applied in 1957, known as the upgraded “IS-2M”.
IS-2 4-view drawing
The range of modifications included an improved fire control system, extending the effective range of the 122 mm (4.72 in), a new prism sight slit for the driver and TVN-2 or NRZ night vision system. Also fitted were a new B-54K-IS engine, electric starter, new lubrication and cooling system, fuel injection heater NICS-1, electric pump MOHP-2 and a VTI-2 air cleaner with improved fire smoke extraction. There was also a new gearbox with oil pump and oil cooling system with a direct rigid attachment at the rear bearing. The planetary rotation mechanism was connected to the host drive final drive with semi-rigid connections. The return rollers were changed as well as the suspension bearings. Internal modifications inside the turret and enhanced recoil system components shared with the T-54 permitted to store 35 rounds. A modern R-113 radio set was also fitted. Externally, stowage bins over the tracks were added, as well as BDSH smoke bombs projectors.
An IS-2 model 1944

The IS-2 in action

Tactically, the IS-2s were deployed with the elite Guards Battalions, which acted on request wherever a strongpoint was encountered. Its capacity to destroy Panthers and Tigers, as well as fortifications with HE rounds, made it irreplaceable. A typical Guard Tank Brigade had 3 regiments of 65 IS-2s each. Independent Guard units also existed with fewer vehicles and with their supply train. Their first action was in February 1944 at Korsun Chevchenkovski, Ukraine. Later, a single unit of 10 IS-2s from the 72nd Regiment engaged and claimed to have destroyed no less than 41 Tigers and “Ferdinands” in several engagements between April and May 1944, claiming the loss of eight tanks. The frontal armor proved impervious to the 88 mm (3.46 in) at usual German firing distances of 1000 m (1093 yards) and more. The same regiment was later committed within the 18th Army to fight-off the General Stanislav’s Axis-equipped Russian forces as part of the 4th Panzer Army.
IS-2M
During one of these battles, near the settlement of Târgu Frumos, a single IS-2 was damaged and later examined by General Guderian himself, whom concluded that the “Stalin” was worth of its name. “Do not get involved in a fight with a “Stalin” without overwhelming numerical superiority in the field. I believe that for every “Stalin” we must account for an entire platoon of Tigers.” Any attempts by a single “Tiger” to fight a “Stalin” one-on-one can only result in the loss of a priceless war machine.” Soon, new tactical rules were devised to flank and surround IS-2s and get shots in its vulnerable sides, rear and the sensitive “shot trap” rear turret basket, and only at short range. Presumably German tactical superiority was again called for the task.
IS-2 in action, Berlin, 1945
On the northern sector many IS-2s were also committed during operation Bagration, the summer 1944 offensive on eastern Germany. During the battle on the Sandomierz bridgehead, on August, 13, 1944, the Germans launched a powerful counter-attack led by brand-new heavy tanks. The battle lasted until the 31st of August, and the Russians, placed on well-prepared fortified defensive positions, claimed four Königstigers and seven damaged, three Panthers and even a giant Jagdtiger SPG. As it appeared later, the eleven IS-2s from the 71st Independent Heavy Tank Regiment had successfully repelled an assault from a total of fourteen Panzer VI Ausf. B Königstiger from the 501st Heavy Panzer Regiment. The battle raged at only 656 yards (600 m) and ended with three IS-2s destroyed and seven damaged.
Soviet heavy IS-2 tank in Berlin (1945)
However, it appeared that the loading rate of the new D-25T was still around 20-30 seconds, during that time a Panther could still fire 6-7 rounds. Plus, the ammo was still cumbersome to use and always in short supply. Other battle honors included the Leningrad front, the Baltic states, with the liberation of Lithuania and Latvia, but the offensive ran short at Tallin, where the 36th Independent Guard Regiment lost three tanks and the remaining already worn-out tanks were damaged when attempting to reduce a series of fortifications. The harsh and marshy terrain of eastern Prussia was not friendly to heavy tanks, which had to deal with a well-prepared, deep defensive perimeter. The 79th Regiment suffered badly there until October, but it was more lucky at the battle of the Narew river.
In Hungary, notably at Debrecen, the 78th Regiment also took heavy losses while claiming to have destroyed no less than 6 Tigers, 30 Panthers, 10 Panzer IVs, 24 SPGs and many defensive positions in the process. In February 1945, the 81st Regiment fought against superior forces at Kukennen, after the capture of Nemeritten. The assault, badly supported and coordinated, was repelled with heavy losses. On the Vistula-Oder, in January 1945, the 80th Regiment was more lucky, destroying 19 tanks and SPGs and many enemy positions, deeply nailing into the German 9th Army.
IS-2, Berlin, 1945
IS-2, Berlin, 1945
The Battle of Berlin saw scores of IS-2s committed to destroying entire buildings thanks to their powerful HE rounds. The assault comprised the 7th separate Guards (104th, 105th and 106th tank regiments), the 11th Heavy Tank Brigade’s 334th Regiment, the 351st, 396th, 394th regiments from various units and the 362nd and 399th regiments from the 1st Guards Tank Army, the 347th from the 2nd Guards Tank Army, all part of the 1st Belorussian Front, and the 383rd and 384th regiments of the 3rd Guards Tank Army (1st Ukrainian front). They were tactically arranged in small units of 5 IS-2s supported by a company of assault infantry, including sappers and flame-throwers. The operation lasted until the 2nd of May 1945, with more than 67 IS-2s destroyed in action, mostly by the “Faustniks” (panzerfausts).

Postwar career

The IS-2M was the new standard of modifications, which was applied to nearly all remaining IS-2s after the war. Before this, the IS-2s had been in the first line for 15 years. This set of overhauls spanned from 1954 to 1958. Starting in 1959, some experiments to convert limited numbers of IS-2s into tactical missile mobile launchers gave several turretless versions. The 8K11 and 8K14 missiles were carried and the modified tanks range increased to 300 km (186 mi). Others were converted as ARVs, in two versions, only differing by the position of the commander cupola. IS-2Ms participated in the Soviet-Chinese border crisis, other were stationed on the Kuriles islands and Sakhalin or later turned into bunkers. They remained in active service long enough to participate in the large-scale maneuvers of Odessa in 1982. After this, all remaining IS-2Ms were stored. As of 1995 they were officially put out of commission and were gradually sold for scrap. Perhaps 100 or less are still in storage.
The IS-2 also equipped future Warsaw pact nations, starting in 1945 with the Polish, Czech and Hungarian armies. Polish tanks took an active part in the final push on Pomerania in 1945, while the Hungarian ones were committed during the 1956 Revolution. Perhaps 100 or less (exact numbers are evasive) were also sent to the Chinese in 1950. It is not known how many took part in the great North Korean counter-offensive in the summer of 1951. Several were also sent to the North-Vietnamese fighting the French colonial forces. In Korea, according to U.S. data actions, the fighting involved four separate tank regiment manned by Chinese volunteers, each of which had three companies of T-34/85s and one of IS-2s.
Eventually, a shipment of IS-2Ms arrived in Cuba in late 1960, but not the following spare parts, prevented by the US blockade during the 1962 crisis. Two regiments of 41 tanks were active but stationed in reserve by Castro, near the sugar factory Australia, and never participated in the “Bay of Pigs” battle. They were all later turned into bunkers for coastal defense.

Unused Design

Nikolai Fedorovich Shashmurin, a well-known tank designer, drew up plans for a possible alternative to the IS-2. Unofficially named the IS-2Sh (Sh = Shashmurin) or simply Shashmurin’s IS-2, it was a complete redesign of the IS. It featured a rear-mounted turret carrying the 122mm gun, large single roadwheels and heavily sloped frontal hull armor. The engine was placed in the middle of the hull, with the driver at the bow cut of off from the rest of the crew. Only one drawing is known to exist of this design.

The only known image of the IS-2 “Sh”.

IS-2 documentary (english subtitles)

IS-2 related links and references

The IS family on Wikipedia
On WWIIvehicles.com
On Battlefield.ru
On Flames of War

IS-2 model 1944 specifications

Dimensions (L-w-h) 6.2 (9.9 with gun) x 3.10 x 2.73 m (20.34/32.48 x 10.17 x 8.96 ft)
Total weight, battle ready 46 tonnes (90,000 lbs)
Crew 4 (commander, loader, gunner, driver)
Propulsion V2 diesel V12, 600 bhp (450 kW)
Speed 37 km/h (23 mph)
Range (road/off road) 240 km (150 mi)
Suspensions Transverse torsion arms
Armament (variable) 122 mm (4.8 in) D-25T
2xDT 7.62 mm (0.3 in) machine guns
DShK 12.7 mm (0.5 in) AA machine gun
Armor thickness 30 to 120 mm (1.18-4.72 in)
Production 3,854

Gallery

IS-2 used as target
IS-2 used as target
IS-2 with the 'Revenge for the Hero Brother' slogan on the side of the turret
Revenge for the Hero Brother’ slogan on the side of the turret
IS-2, Bohemia, Czech Republic, 1945
IS-2, Bohemia, Czech Republic, 1945
Close view of the DSHK machine gun in action
Close view of the DSHK machine gun in action
ww2 soviet armour
ww2 Soviet Tanks Poster

IS-1 model 1943, for comparison
IS-1 model 1943, for comparison.
IS-2 model 1943, 88th Independent Guards Heavy Tank Regiment, Berlin, April 1945.
IS-2 model 1943, 88th Independent Guards Heavy Tank Regiment, Berlin, April 1945.
IS-2 model 1943, Berlin, April 1945, General Rybalko's 3rd Guards Tank Army.
IS-2 model 1943, Berlin, April 1945, General Rybalko’s 3rd Guards Tank Army.
IS-2 model 1943, winter 1943-44, Vitebsk sector
IS-2 model 1943, winter 1943-44, Vitebsk sector.
IS-2 Model 1944, 29th Guards Heavy Tank Battalion, Poland, early 1945
Model 1944, 29th Guards Heavy Tank Battalion, Poland, early 1945.
A partially camouflaged IS-2 model 1944 from an unknown Guards Heavy Tank Regiment, late 1944.
A partially camouflaged IS-2 model 1944 from an unknown Guards Heavy Tank Regiment, late 1944.
Camouflaged IS-2, 4th Guards Tank Army, summer 1944
Camouflaged IS-2, 4th Guards Tank Army, summer 1944.
IS-2 model 1944 from the 7th Independent Guards Heavy Tank Battalion, Berlin, April 1945.
IS-2 model 1944 from the 7th Independent Guards Heavy Tank Battalion, Berlin, April 1945. Number 434 was named “Combat Girlfriend” and fought in the southeastern Berlin suburbs as part of Chuykov’s 8th Guards Army. They had a polar bear painted over a red star to commemorate their participation in the previous Karelian campaign.
IS-2 model 1944 from an unknown unit, Karelia, 1944
IS-2 model 1944 from an unknown unit, Karelia, 1944.
Artist impression of a late IS-2 with a IS-1 turret, quite possibly a marriage made when both tanks suffered damaged, one to the hull, the other to the turret
Artist impression of an IS-2 with a IS-1 turret, quite possibly a marriage made when both tanks suffered damaged, one to the hull, the other to the turret. Inspired by the scale model work of Ulf Andersson, https://www.plasticwarfare.se.
IS-2, unknown Guards Independent Unit, Seelow heights, March-April 1945
Unknown Guards Independent Unit, Seelow heights, March-April 1945.
IS-2 Model 1944, partial winter camouflage, Eastern Prussia, February 1945
Model 1944, partial winter camouflage, Eastern Prussia, February 1945
1st Czechoslovak Tank Brigade, Prague, May 1945.
1st Czechoslovak Tank Brigade, Prague, May 1945.
Polish 4th Heavy Tank Regiment, Germany april 1945
Polish 4th Heavy Tank Regiment, Germany, April 1945.

IS-2 of the People’s Liberation Army, on parade in Beijing, 1954.
IS-2M, modernized version with stowage bins over tracks and other modifications, 1957.
IS-2M, modernized version with stowage bins over tracks and other modifications, 1957.

Categories
WWII Soviet Heavy Tanks

IS-1

Soviet Union (1943) Heavy tank – 207 built

Based on the KV-85

The origin of the IS-1 project came from numerous reports regarding the KV-1. Even in its faster version, the KV-1S, offered no greater fighting capabilities than the T-34, while costing much more and being more labor intensive. Stalin nearly cancelled all heavy tank development in 1943 but, in that summer, the Panther and Tiger were seen in action. Heavy tanks had to be improved, both in protection and firepower, to adequately cope with the new threats.

IS-85 prototype, IS-1
In March 1943, an order specified the rearming of all frontline tanks. One of the guns intended for this was an AA gun roughly similar in performance to the German 88 mm (3.46 in), of which one had been disabled, captured and the gun analysed. This resulted in the stopgap KV-85 heavy tank, only produced in limited numbers (143 machines). This vehicle set the tone for further improvements, being the basis of the long “Iosif Stalin” series. The KV-85 turret was brand new, well adapted to the new gun designs. It could hold three men, but the hull remained basically the same KV-1 flat-armored hull first designed for the multi-turreted SMK back in 1939.

The KV-13 program

The KV-13 project was launched by SKB-2, Chelyabinsk Kirov Plant’s design bureau, as early as late 1941. It tried to create a “universal tank”, a crossover of the KV-1 and T-34, resulting in the prototype Obyekt 233 tested in the spring of 1942. The tank was ultimately rejected as failing many specifications, mainly reliability, armor protection and for having a two-man turret design. However, the KV-13 program would lead to two other modified prototypes, which would serve to test the new IS-85 program in early 1943.

The IS-85 design

The new IS-85 was to address this issue with a brand new sloped hull design directly inspired by the KV-13. This was a stout armor layout designed to deflect or resist shots at all angles. However, the initial armor was designed to stop only Panzer III 50 mm (1.97 in) rounds, and needed to be massively thickened. The only strict design specification was to not exceed the weight of the original KV-1. The new armament was the same as the interim KV-85, the excellent D-5T 85 mm (3.35 in) gun, which had a far greater range and initial velocity than the previous F-34. The turret was also the same as the KV-85, housing three men, a commander cupola (rear left side) and a rear ball-mount DT machine-gun. A second one was mounted in the hull and the third coaxial with the gun, firing tracers which served to adjust the main gun. Ammo storage consisted of 59 85 mm (3.35 in) rounds and 2520 rounds for the three DT machine guns.

Comparison Armour scheme IS-1/IS-2

The drivetrain was essentially the same as the one on the KV-1, with large tracks supported by three pairs of double return rollers, and six double-tired wheels suspended by massive torsion arms. Like previous vehicles, extra fuel tanks were attached to the rear of the hull, while the large mudguards accommodated storage boxes. The engine was changed to the new V2-IS 12-cylinder diesel providing 520 horsepower. Top speed was 37 km/h (23 mph) on average, and the practical range only 150 km (93 miles).

Production of the IS-1

The IS-85 (Obyekt 235) prototype started its successful but rushed trials in mid-1943. Production was assumed by Chelyabinsk Kirov Plant. The first IS-1 (definitive series vehicles) rolled of the line in October 1943, but it was stopped in January 1944, as the IS-1 was quickly replaced by the all-better IS-2. Because of this, only 200 to 207 were produced. However, it was a considerable improvement over the previous KV-85 and the T-34/76. The appearance of the new T-34/85 medium tank caused the IS series to evolve, and to be logically up-gunned. So, in January 1944, many IS-1s not yet delivered to the front were up-gunned. The IS-1 also tested a new 100 mm (3.94 in) gun and went into comparative trials with the IS-122, favorable to the latter. The new A-19 122 mm (4.80 in) gun had the punch to get through the armor of a Tiger at medium range.
KV-85
KV-85, an earlier transitional model.

The IS-1 in action

The first IS-1s delivered were issued to Guards Heavy Tank Regiments reforming after the summer’s heavy fighting. The IS-85 was issued to the 1st, 8th and 13th Guards Heavy Tank Regiments in Ukraine. These were heavily engaged in early 1944 at Starokonstantinov, Korsun-Shevshenkovskiy and Fastov Station west of Kiev. Later on, most IS-1s were found engaged in Slovakia, and were later given to Slovakian free units during the uprising.

IS-1 links and references

The IS-1 on WWIIVehicles.com
The IS-1 on Flames of War
ww2 soviet armour
ww2 Soviet Tanks Poster

IS-1 specifications

Dimensions (L-w-h) 6.60 (8.56 with gun) x 3.07 x 2.74 m (28.08 x 9.84 x 8.99 ft)
Total weight, battle ready 43.54 tons (95,800 lbs)
Crew 4 (commander, loader, gunner, driver)
Propulsion V2-IS 12-cylinder diesel, 2368 cu in/39 liters, 520 hp
Speed 37 km/h (23 mph)
Suspensions Transverse torsion arms
Range (road) 150 km (93 mi)
Armament 85 mm (3.35 in) D5T
3 x 7.62 mm (0.3 in) DT machine guns
Armor thickness 30 to 120 mm (1.18-4.72 in)
Total production 207

ww2 soviet armour
ww2 Soviet Tanks Poster

IS-85 from the 8th or 13th Guards Heavy Tank Regiment, Ukraine, December 1943.
IS-85 from the 8th or 13th Guards Heavy Tank Regiment, Ukraine, December 1943.
IS-1, definitive production version in early 1944. Unknown unit.
IS-1, definitive production version in early 1944. Unknown unit.
IS-1, 12th Guards Heavy Tank Brigade, Dukla pass, Slovakia, September 1944.4
12th Guards Heavy Tank Brigade, Dukla pass, Slovakia, September 1944.
IS-1, 1st Guards Breakthrough Heavy Tank Regiment from the 11th Guards Tank Corps, 1st Tank Army, 1st Ukrainian Front, Ukraine, March 1944
1st Guards Breakthrough Heavy Tank Regiment from the 11th Guards Tank Corps, 1st Tank Army, 1st Ukrainian Front, Ukraine, March 1944.