KV-2 – When the Soviets put a 152 mm Gun on a KV-1

The KV-2 is a tank that needs no introduction, with its massive, boxy turret, 152 mm gun and KV-1 basis it was destined to be a legend. The tank may be one of the most well known armored vehicles found in video games, but its real-life performance was actually quite poor.

The KV-2 was a development of the KV-1.

The KV-1 heavy tank was an innovative design at the time of its introduction, and provided sterling service at times in resisting the massive German assault on European Russia during Operation Barbarossa in June 1941.

However, the KV-1 had many inadequacies which limited its general usefulness to the Red Army, and some of these design flaws were identified quite early on in its procurement process.

KV-1 heavy tank.
The KV-1 heavy tank, the basis of the KV-2. Image by 270862 CC BY-ND 2.0.

One of these drawbacks was firepower, with the main gun of the KV-1 being identical to that equipping the Soviet Union’s main medium tank, the T-34/76. While perfectly adequate in tank-on-tank combat, the 76.2 mm cannon was not enough for anti-fortification work like bunker-busting.

Accordingly, the Soviet General Staff initiated a program to design an up-gunned version of the KV-1 which would be fitted with a 152 mm howitzer, capable of dealing with fortifications. This new design became known as the KV-2.

Contents

Background

The KV-2’s story is heavily linked to the KV-1, an important tank that we covered here.

The KV-1 began as a simpler and smaller version of the SMK heavy tank, which had two turrets. The SMK, and similar T-100 were themselves designed in the late 1930s to replace the T-35 heavy tank.

Designers of the SMK produced this simplified version privately, without a state requirement, as they were aware of the inherent issues with multi-turreted designs.

Test models of the T-100 and SMK, along with an example of the KV-1 were sent to Finland for combat evaluation during the Winter War of 1939-40. While the KV-1 was a simpler version of the SMK, it was deemed more successful than its competitors and was the only model selected for manufacture.

The SMK heavy tank.
The mighty SMK. It is a clear KV-1 relative.

However, the Soviets ran into the formidable Mannerheim Line and other fortifications in Finland which illustrated a weakness in Soviet armored capabilities; it lacked an armored assault vehicle able to demolish heavy bunkers. Red Army commanders in Finland often had to resort to requesting heavy self-propelled guns to tackle this particular problem.

A requirement was put out for a tank that mounted a 152 mm or 203 mm gun to solve this limitation.

In the scramble to fulfil this requirement, the Kirov Plant, which designed the KV-1, made a proposal to place a howitzer in a re-designed turret on the basic KV-1 chassis, as the vehicle had proved moderately satisfactory in most other regards.

The SU-100Y front quarter.
Another vehicle built to achieve these specifications was the SU-100Y, based on the T-100. Image by Uwe Brodrecht CC BY-SA 2.0.

The Kirov Plant had a prototype ready in January 1940. Before it was named the KV-2, it was simply known as the “large turret” KV (KV standing for Kliment Voroshilov, a Soviet politician).

Two prototypes were sent for evaluation to Finland, and while initial feedback stated they performed well in their intended role, later reports confirm that these tests were conducted against bunkers that had already been captured. Still, the KV-2 showed some promise, as one was reportedly hit 48 times and survived.

The KV-2 was authorised for production later in the year, with the entire production run taking place at the Kirov Plant in Leningrad.

The KV-2

An early, limited production run of the KV-2 were equipped with a 122 mm (4.8 inch) howitzer, but the primary production stream saw the adoption of the M-10T 152 mm (5.9 inch) howitzer as the main gun, with the earlier models being retro-fitted with this weapon.

The many drawbacks of the basic design of the KV-2 became more apparent during the early part of the Great Patriotic War, and as a result only limited numbers were made. Production was curtailed from 1941, when most Soviet factories were relocated to the Urals. Only 203 examples were built, including several prototypes of sub-variants which were not accepted for further procurement.

KV-2 prototype.
The first KV-2 prototype in 1940.

The KV-2 employed the same basic chassis and drivetrain combination as that of the KV-1, with the power plant being the V2-K diesel V-12, and the Holt-Caterpillar gearbox with 5-forward and 1 reverse gears. This combined assembly was barely adequate in the parent vehicle, with the transmission being particularly unreliable, but the increased size and weight of the KV-2 only acerbated these shortcomings.

The other statistics of the KV-2’s hull were identical to that of the basic KV-1; two fuel tanks held a total of 615 litres of diesel, and the tracks were 650mm in diameter.

The combination of a massive turret and a large cannon meant that the weight of the KV-2 came in at 57 tons, compared to 50 tons of the KV-1.

KV-2 knocked out inspection.
The KV-2 was an enormous vehicle, and must have garnered large amounts of attention from intrigued troops.

With no increase in engine power from the basic KV-1 chassis, the fitted drive train assembly returned even poorer performance figures for the KV-2 in service; a top speed on level ground of 25.6kmh (15.9mph), and a dismal cross-country speed of 12kmh (7.5mph). The range of the vehicle was underwhelming as well, even on level surfaces the KV-2 had a combat range of only 175km (110 miles).

Turret and 152 mm Gun

To accommodate the massive 152mm howitzer, an entirely new turret was designed and manufactured to fit on the basic KV-1 chassis. This box-shaped structure weighed in at 14 tons by itself, and gave the KV-2 a height of 4.9 metres (16 feet) – a full metre taller than its predecessor.

The first few built were produced with an angular turret that had sloping cheeks made from separate plates, and a “V”-shaped rear. Also, the gun mantlet was surrounded by large bolts. However the bulk of production saw a more simplistic turret used, with a basic mantlet and single-piece side armor.

As this turret was fully revolving, it can be said that the KV-2’s 152 mm gun was the largest ever fitted to a production tank, even if the vehicle was primarily employed as mobile artillery.

KV-2 turret.
The 152 mm M-10T howitzer in the turret of a KV-2. Terminator216 CC BY-SA 4.0.

The M-10T was based on the M-10 howitzer, and the two could actually share ammunition. This actually did happen due to supply issues, even though a “standard” KV-2 only carried the 40 kg OF-530 high-explosive round.

It had 75 mm of armor on the turret front, and 75 mm (3 inch) of plating on the sides and rear.

Thirty six main gun rounds were carried in front-line service. The KV-2 was provided with two 7.62 mm DT-29 machine guns, one mounted in a ball mount at the rear of the turret, and the other in the hull front, which was used by the radio operator. 3,000 rounds of ammunition for these auxiliary weapons was supplied.

KV-2 captured by the Germans.
A captured KV-2 in German service. Note the turret door and machine gun mount at the back of the turret.

There were six crew members in a KV-2; commander, driver, gunner, radio operator/bow gunner and two loaders – the two-piece ammunition for the M-10T howitzer required an extra loader to achieve even a reasonable rate of fire.

But the very weight of the turret led to some unique problems from an operational perspective.

The turret of the KV-2 was so heavy and unbalanced that the vehicle had to be on fairly level ground for the turret to safely traverse, and its weight was so immense that the it had serious stability issues on rough terrain. In some instances the turret could tip the entire vehicle over if the angle of the chassis was at too much of an incline.

KV-2 abandoned of the side of the road.
The KV-2’s unbalanced turret could prevent the tank from engaging the enemy on a slight incline.

The main gun could only be fired at certain directions relative to the chassis, as it could cause further stability issues or in extreme cases was known to damage or destroy the turret ring, rendering the vehicle useless for further use.

Combat Record

The KV-2 was nicknamed the ‘Dreadnought’ by its crews, and its initial employment in the Winter War was moderately successful. The two prototypes employed in this conflict supposedly did engage in combat (accounts vary), and Finnish anti-tank gun crews were unable to successfully stop the vehicle due to its immensely thick armour.

However the vehicle did suffer greatly from reliability and mobility issues, and these were only made more apparent when the platform was used against the better-armed Wehrmacht during the invasion of the Soviet Union in 1941.

KV-2 knocked out in water.
An early KV-2 in quite a poor state; in water, penetrated and suffering damage to its recoil mechanism, causing the gun to sit back inside the tank.

The many design drawbacks of the KV-2 became glaringly obvious during the first year of Operation Barbarossa. As is the case with many stop-gap or emergency procurement programs, the vehicle’s inadequacies were a result of adapting the already over-strained driveline of the KV-1 to attempt to power the far heavier and bulkier KV-2 in combat.

In fact, the KV-2 inherited, and then exacerbated the KV-1’s notable problems.

Like the KV-1, the poorly thought-out turret also contributed to the general ineffectiveness of the vehicle. Its unenviable combat record meant that the platform was generally disliked by its operating crews, and led to the early retirement of the KV-2 from front-line duties.

KV-2 from Raseiniai.
This particular vehicle was at the Battle of Raseiniai.

The large bulky turret of the KV-2 was a glaring weakness with many drawbacks which imposed severe limitations on crew comfort and combat utility. The tall profile of the turret greatly increased the vehicle’s visibility, and was more easily spotted by tanks and anti-tank gun crews.

Additionally, while the thick armour protected the crew from the earlier generations of anti-tank guns employed by the Wehrmacht in 1941, Germany’s high-velocity anti-armour weapons such as the 75 mm Pak 40, not to mention the legendary 88 mm gun, were both able to successfully combat the KV-2 at normal combat ranges.

The turret also had design defects which further hindered the KV-2’s crew. The commander had no hatch of his own, and his observational capacity was limited to a revolving periscope with a restricted field of view. This reduced combat awareness was also experienced by the rest of the crew, as the turret severely hampered observation by any member of the gun team.

KV-2 in Russia.
Like the KV-1, the KV-2’s crew operated in discomfort and with a lack of awareness of what was happening around them. Image by Gandvik CC BY-SA 3.0.

The German Army listed many accounts of KV-2s blundering around the battlefield being totally lost due to lousy situational awareness, and becoming easy targets for German tanks and other anti-armour weapon systems.

The increased weight of armour and the bulky configuration of the turret severely limited mobility, and the KV-2 was even more limited in its operational manoeuvrability compared to its predecessor, restricted to level surfaces and only the strongest of bridges when traversing water bodies.

An unreliable and over-strained driveline was even more susceptible to breakdown than in the KV-1, and the vehicle was so heavy and unwieldly that if the KV-2 was immobilised for any reason, the vehicle could only be recovered in the tactical situation was extremely favourable. The few examples that were captured and used by the German Army were instantly abandoned by their crews if incapacitated, as it was not deemed worthwhile to attempt to recover the vehicle.

Conclusion

The KV-2 is a prime example of a bad idea made much worse. While the basic KV-1 served valiantly in the Red Army despite its many limitations, it had enough redeeming features to hold its own against German armour during the first year of Operation Barbarossa.

Hastily re-designed and adapted from this platform, the KV-2 often found failure when employed in a combat capacity, and the modest advantages of the increased fire-power of its 152 mm howitzer were not enough to compensate for its miserable mobility and performance shortcomings, along with command and control problems facing the crew in combat due to design limitations.

KV-2 in Moscow.
The last surviving KV-2, on the left. Валерий Дед CC BY 3.0.

All these issues led to the KV-2 having an extremely lacklustre service record. The Red Army crews knew a lemon when they saw one, and were not shy about making complaints about the general unsuitability of the vehicle in combat conditions.

This meant that manufacture of the KV-2 was swiftly curtailed in late 1941, and the vehicle was withdrawn from front-line service the next year. All in all, the KV-2 remains a very unsatisfactory footnote to the larger story of its predecessor, the KV-1.