Soviet Union (1941)
Super Heavy Tank – Blueprints Only
The KV-4 heavy tank program was born from the perceived need for a much more powerful heavy tank than its predecessors. It was designed at the SKB-2 design bureau via a thorough competition. Thus, several different versions were proposed, including the one by G.N. Moskvin. Although the tank had a very traditional design, his design was not rewarded in the competition and forgotten. Nowadays, it is playable in Wargaming’s ‘World of Tanks’ video game.
KV-4 by Moskvin, as represented in World of Tanks. Though several details are missing or inaccurately modeled, it offers a good overall perspective on its design. Source; in-game screenshot
Development
–Dear reader: A more detailed development analysis of the KV-4 program can be found in the KV-4 Dukhov article–
The development of the Soviet KV-4 heavy tank, designated as Object 224, began in March 1941. The development of a 90-tonne German tank was reported in a letter from the Soviet Intelligence Services on 11 March 1941, which alarmed the Soviet military officials, leading to the GABTU requesting the development of a new super-heavy tank. The KV-4 was to weigh 70-72 tonnes, be armed with the 107 mm ZiS-6 in the turret, and have 130 mm thick armor at the front and 120 mm towards the sides and rear. The deadline for the tank design was set to 17 July 1941, with the prototype building and armament testing set for October of the same year.
However, on 7 April 1941, the GABTU revised their requests, raising the weight to 75 tonnes and the armor thickness to 135 mm at the front and 125 mm towards the sides and rear. The blueprints’ deadline was also narrowed to 15 June 1941. At the same time, the KV-5 was requested, a tank that would weigh at least 90 tonnes, have 170 mm of armor at the front, and 150 mm at the sides. Additionally, the KV-3 was ‘revived’ and improved to fulfill a stopgap role until the KV-4 and KV-5 tanks were ready for production.
At LKZ (Kirov Leningrad Factory), the SKB-2 design bureau began work on the KV-4 on 10 April 1941. The head of the project was J. Y. Kotin, who created a competition between the SKB-2 engineers, with the top few designs receiving financial rewards. Over 20 engineers competed, submitting over 20 individual designs. The winning design was that of N. L. Dukhov, which was essentially an enlarged KV-220. Second place went to the K. I. Kuzmin, V. I. Tarotko, and P. S. Tarapatin trio, who submitted a tank with the main gun in the hull and secondary gun in a small turret. Third place went to N. V. Tseits, who submitted a tank with a very low hull but large turret to offset the lack of hull space.
Despite the efforts put into the development of the KV-4, it never saw production. The outbreak of World War II on 22 June 1941 disrupted the Soviet tank development program, and the resources were redirected to immediate production of already existing designs. Additionally, the heavy losses suffered by the Soviet army during the initial stages of the war showed that the development of heavy tanks was not a priority. The KV-4 project was eventually canceled, and the KV-3 was abandoned as well, with the resources redirected to the development of the IS series of tanks.
G.N. Moskvin
Born in November 1909 in Nizhny Novgorod, Grigory Nikolaevich Moskvin began working at a waterway administration and later at the Svetlana Plant. In 1931, he was drafted into military service, and shortly thereafter was assigned to the design bureau of the Artillery Institute (SKB-4) at the Leningrad Kirov Plant. There, he would work on various self-propelled gun systems, such as the SU-14, SU-5 series of SPGs, SU-6 and armament system of the T-111 tank. He also worked on the design of tanks at Plant No.185, but was fired due to his brother’s arrest. In 1940, Moskvin was hired by the SKB-2 heavy tank design bureau. Here he worked on the T-50 light tank, KV-220, KV-4, and, after SKB-2s transfer to ChTZ and the start of the Second World War, he worked on the KV-7, KV-13, SU-152, and ISU-152. He also participated in the design of the well-known ‘pike nose’ of the IS-3 heavy tank. After the war, he worked on heavy tank armor, as well as other projects, such as the Object 740/750 and PST-54. Prior to his retirement in 1972, he worked on the development of the Lunokhod lunar rover project. He later passed away in 1986, aged 77.
Moskvin had been awarded the Order of Lenin, The Stalin Prize, Order of the Patriotic War and Order of the Badge of Honor.
G.N. Moskvin in 1943. Source: TiV No.11 2013
Design
Unlike most other KV-4 designs, Moskvin provided detailed drawings of his design, from all relevant angles. The tank was to weigh 101 tonnes on paper, being 9.573 meters long, 4.03 m wide and 3.74 m tall.
The tank had a standard layout, with the turret in the center and the powerpack in the middle. The hull was akin to most previous KV tanks, with a stepped front plate, flat sides, and a large engine deck, with its unique engine cooling system vent at the rear.
The main turret was very large, to be able to accommodate both the large main gun and the secondary turret, mounted at the rear of the turret. Ammunition was stowed underneath the main turret ring, for both the main and secondary guns.
The mantlet was mounted over the frontal curved turret plate and protected by two ‘fins’ on either side, protecting the internal mechanism from outside elements. The side walls were curved, offering great effective protection frontally, with small arm firing ports in the center. The secondary turret had a cupola with an unspecified amount of periscopes, for clear battlefield vision.
The engine was a 1,200 hp M-40 aviation engine, boosted with the help of four TK-88 turbochargers. It was connected directly to the final drives and sprockets, at the rear.
Blueprints of Moskvin’s KV-4 design, with a cutout view of the interior from the side, and top view of the hull interior Source: Stalin Supertanks IS-7Front view of the tank, as well as a cutout of the front and top of the turret. Source: Stalin Supertanks IS-7
Crew
The crew likely consisted of 8 men, commander, main gunner, 2x main loaders, secondary gunner, secondary loader, driver, and bow machine gun/radio operator.
The gunner sat in the front of the turret, to the left side of the gun, and the commander sat right behind him. The two main loaders were seated on stools slightly facing the gun, on its right side. From here, the loader in the front could pass on shells from the front side wall or hull, while the rear loader could operate the breech and load the shells. Behind the gun breech, the two crewmen for the secondary turret were seated, gunner and loader. They were seated on either side of the 45 mm gun with enough clearance from the main gun breech.
In the front of the hull, the driver and radio operator had their positions. The latter would operate the flamethrower, while the driver operated the ball-mount machine gun.
Armament
The main armament was the 107 mm ZiS-6 gun developed at Plant No.92 by V.G. Grabin in early 1941. It was specifically developed to be fitted on the KV series of heavy tanks. It offered excellent anti-tank capabilities, with an alleged penetration of 120 mm angled at 30° from 1,600 meters. The shells were 120 cm long and weighed 18.8 kg.
Secondary armament was the 20-K 45 mm gun mounted in the secondary turret, as well as 2 or 3 DS-39 7.62 mm machine guns which were mounted in ball mounts and coaxially. A flamethrower was also mounted in the front of the hull. These secondary weapons offered, on paper, adequate offensive power against both soft-skin vehicles and infantry.
Armor
The massive 101 tonne tank was very well protected for its time. The front hull and turret plates were 130 mm thick, while the side and rear plates were 125 mm thick. The secondary turret was also 125 mm thick all around, offering great protection at the cost of a very cramped interior.
Fate of the project
After the announcement of the competition winners, work on the KV-4 did not progress any further. Engineers from SKB-2 shifted their attention to the design of the KV-3, with a full-scale mockup of it built. In June, work on the KV-5 also began, based on the winning designs of the KV-4, hence why its appearance was similar to that of the KV-4 by N.V. Tseits.
However, with the start of the war, the LKZ plant had to focus on the realities of war. More KV-1 tanks had to be built, and large numbers had to be repaired. As such, work on these super heavy tanks slowed down. The situation turned sour in August and September, when German forces were advancing towards Leningrad and the SKB-2 design bureau was transferred to ChTZ in Chelyabinsk. The heavy KV designs were left behind and never brought up again. Only the KV-3 was still being discussed, but it eventually faded away as well.
Conclusion
The KV-4 heavy tank program was born as a counter to the elusive German heavy tank developments (specifically the Löwe) which themselves hardly materialized. While the nature of development via competition brought up innovative features, the realities of the situation and the start of the war required the Soviet tank industry to focus on realistic targets. The Soviet tank arsenal was heavily outclassed across most elements, and while propagandistic stories of the T-35 and KV-1 shined, their unreliability and lack of combat effectiveness led to the need for better heavy tanks. The even heavier KV-4 was certainly not the answer.
KV-4 by G.N. Moskvin, ilustration by Pavel Alexe.
KV-4 Moskvin Specifications
Dimensions (L-W-H) (approx.)
9.573 x 4.03 x 3.74 m
Total weight, battle-ready
101 tonnes
Crew
8 (commander, main gunner, 2x main loaders, driver, secondary gunner, secondary loader)
Propulsion
1,200 hp diesel V-12 M-40 with 4 TK-88 turbochargers
Speed
40 km/h (hypothetical)
Armament
107 mm ZiS-6 (F-42)
45 mm 20-K
3x DS-39 7.62 mm machine guns
Flamethrower
Armor
Front: 130 mm
Sides: 125 mm
Rear: 125 mm
Roof & belly; 50 mm
KV-4 (Object 224) Buganov. Illustration by Pavel Alexe.
Soviet Union (1941)
Super Heavy Tank – Blueprints Only
In spring of 1941, the Soviets were working on KV-1 replacements of various sizes and weights, from the moderate upgrade T-150, to the much larger KV-220. But rumors of German super heavy tank projects catalyzed the development of a variety of even larger heavy tank projects, one of them being the KV-4. Its development consisted of a tank design competition, in which engineer K.I. Buganov participated. His unusual proposal was appreciated and was awarded sixth place in the competition.
Development
–Dear reader: A more detailed development analysis of the KV-4 program can be found in the KV-4 Dukhov article–
The Soviet Union was caught off guard in 1941 when intelligence reports revealed that Germany was developing a 90-tonne heavy tank armed with a 105 mm gun. The Soviets realized that their existing heavy tanks, the T-35 and the KV-1, were not enough to match the German threat. Work on developing heavier tanks commenced, and on 21 March 1941, the GABTU sent requirements to LKZ for the development of the KV-4, designated Object 224.
The KV-4 was required to be a 70-72 tonne heavy tank armed with a 107 mm ZiS-6 gun, a secondary 45 mm 20-K gun, and at least three DT machine guns. Armor was to be 130 mm at the front and 120 mm towards the sides and rear. Propulsion was to be provided by a 1,200 hp M-40 engine, also developed at LKZ, and the crew was to consist of six. The deadline for the blueprints was set for July 17, 1941.
On 7 April, the GABTU completely redesigned their request, introducing two new heavy tanks, the KV-3 (Object 223) and KV-5 (Object 225). The KV-3 was based on the previous KV-220, but with thicker 120 mm armor and the larger 107 mm ZiS-6 gun. It was intended as a stopgap vehicle, until the KV-4 and KV-5 were ready for production. The KV-5 was an even larger heavy tank, weighing at least 100 tonnes, and with armor of 170 mm at the front and 150 mm at the sides and rear. The KV-4, to better fit in between these two tanks, was also edited, with side and rear armor increased to 125 mm and weight threshold increased to at least 75 tonnes.
Work on the KV-4 began on April 10, 1941, with J. Y. Kotin as the head of the project. Kotin set up a competition for the tank’s design, encouraging engineers to come up with original and innovative features. Over 24 engineers submitted more than 20 individual designs, and the winning design was that of N. L. Dukhov. Second place went to K. I. Kuzmin, V. I. Tarotko, and P. S. Tarapatin, who designed a tank with the gun mounted in a central rotating sponson, with a smaller turret on top. Third place went to N.V. Tseits, with a more conventional design, featuring a very large turret and low-profile hull.
Work on the KV-4 stagnated after the end of the competition and was further delayed by the German invasion of the Soviet Union in June 1941. Despite this setback, the project was still active, but most of the focus had shifted to the KV-5, which was being developed by the winners of the KV-4 competition.
One of the designs submitted was by SKB-2 engineer K.I. Buganov. His tank’s unique and unorthodox features allowed his proposal to receive the sixth place prize of 1,000 rubles.
K.I. Buganov
K.I. Buganov began his military engineering career at the Experimental Design Machine-Building Department (OKMO), working on earlier Soviet tank designs, such as the T-28 and T-35, and in the late 1930s was transferred to the SKB-2 design bureau. After 1951, Buganov worked under Kotin at the Special Design Bureau of Heavy Tanks, as head of the hull and armor testing section, and in 1952, as part of VNII-100, he was chief-designer of the Object 907 medium tank.
Unfortunately, no further information on K.I. Buganov could be found publicly.
Design
The design presented by Buganov for the KV-4 was all but conventional. The engine and final drive were moved to the front, as opposed to the other KV tanks, and the main turret was moved to the rear, with the secondary turret on top. Furthest back were the fuel tanks.
To allow for a narrower hull but still a large turret, the turret had ‘lips’ protruding from either side of the hull, allowing for full 360° rotation. The main turret shape was peculiar as well, resembling a disk segment, with heavily sloped turret cheeks on either side.
The secondary turret was mounted on the right side of the main turret, and was of an usual design, akin to that of the T-50 light tank. It was capable of full 360° rotation, independent of the main turret.
Due to the narrowness and shortness of the hull, the engine bay area was exceptionally small. Thus, the entire air cooling and intake systems were moved into sponsons on the sides of the hull.
The ammunition was stowed both horizontally and vertically at the bottom of the fighting compartment, starting from the engine bay firewall, all the way through to the fuel tank.
Side and top cross-view of Buganov’s KV-4 design. Note the bizarre shape of the turret.
Source: Yuri Pasholok Front view of Buganov’s KV-4 and a cross-section of the engine bay, showing the cooling system sponsons.
Source: Stalin Supertanks IS-7
Crew
The only information provided regarding the crew is the number, six n. However, due to the peculiarities of the design, it is challenging to accurately assign what roles these six crew members had, and where their exact positions were.
One hypothesis is that the crew consisted of a commander, main gunner, main loader, secondary gunner, secondary loader, and driver. The main gunner and commander would have been to the left of the gun, while the secondary gunner and loader would have been high in the secondary turret. The main loader would have been underneath the secondary turret, with ample access to the ammunition stowage below. The driver would have sat alone in the hull’s front and driven the tank, as well as fired the ball-mounted DS-39 machine gun.
Another theory is that the commander was also the gunner of the secondary turret. This would have given him an excellent view of the battlefield, but burdened him with the task of also aiming and firing the secondary gun. The sixth crew member in this case would be the radio-operator/bow machine gun, seated on the right side of the hull, opposite to the driver.
Armament
Much like the other KV-4 designs, the tank was armed with the new 107 mm ZiS-6 (F-42) gun, developed at Plant No.92 by V.G. Grabin in late 1940, early 1941. It was first tested on a tank platform on a specially modified KV-2 in June 1940, where it proved to be a formidable anti-tank weapon. It fired a 120 cm, 18.8 kg shell at 800 to 840 m/s, penetrating 115 mm of armor at 1,000 m.
The secondary armament consisted of a single 20-K 45 mm gun and 3x DS-39 7.62 mm medium machine guns, one in the hull (ball-mounted) and one mounted coaxially to each cannon.
The 20-K, though older in design, was still one of the most common guns used on Soviet armor, in tanks such as the BT-series fast tanks, T-26 and T-50 light tanks, or T-35 heavy tanks. Though comparatively obsolete by 1941 as an anti-tank weapon, as proven by the aforementioned tanks in the first stages of Operation Barbarossa, it was still a viable weapon against infantry and soft skin vehicles.
Armor
The hull was built out of 125 mm thick armored plates, stamped into shape, like on the rounded portion of the front, covering the transmission and final drive. The sides and rear were equally thick. The front of the main turret was 140 mm thick, with the cheeks angled outwards, angled at 45°. Less critical areas such as the hull belly and hull/turret decks were 50 mm thick.
Fate of the Project
After the competition had ended in May, nothing new was documented regarding the KV-4. Instead, most work shifted towards developing the KV-5. Things took a turn for the worse with the Axi’ invasion of the Soviet Union. As a result, LKZ had to shift focus from prototypes to KV-1 tank production and repairs. Nonetheless, work on the KV-5 still continued until August, when German forces began approaching Leningrad, home of LKZ. Consequently, the SKB-2 design bureau was disbanded and members were moved to ChTZ in Chelyabinsk. Aside from a few select projects, most tank programs were left behind, including the KV-4 and KV-5.
Conclusion
Born around the fear of German tank rumors, the KV-4 tank program was very short-lived and arguably a large waste of efforts and resources. Yet its circumstances, oversize proportions and capabilities, and, most importantly, the original tank design competition make it one of the more fascinating Soviet tank programs of the period. Buganov’s entry for the competition was in no way less peculiar, with a very bizarre approach in overall layout and using a variety of quirky features. For these ‘accomplishments’, he was awarded sixth place.
KV-4 (Object 224) Buganov. Illustration by Pavel Alexe.
KV-4 Buganov Specifications
Dimensions (L-W-H) (approx.)
7.7 x 3.8 x 3.32 m
Total weight, battle-ready
83 tonnes
Crew
6 (commander, main gunner, 2x main loaders, driver, secondary gunner, secondary loader)
Propulsion
1,200 hp diesel V-12 M-40 with 4 TK-88 turbochargers
Speed
50 km/h (hypothetical)
Suspension
Torsion bar, 8 wheels per side
Armament
107 mm ZiS-6 (F-42)
45 mm 20-K
3x DS-39 7.62 mm machine guns
Armor
Hull: 125 mm
Turret front: 140 mm
Turret rear: 110 mm
Top & belly: 50 mm
KV-4 Pereverzev variant with a shorter turret. Illustration by Pavel Alexe.
Soviet Union (1941)
Super Heavy Tank – Blueprints Only
Based on rumors of German heavy tank developments, the Soviets expanded their heavy tank programs in the spring of 1941. One of these projects was that of the KV-4, which entailed a competition among several designers from the SKB-2 design bureau. One of these proposed designs came from military engineer L.N. Pereverzev, who proposed a massive 100-tonne tank, with several unique features, such as tracks returning over the entirety of the hull. For his efforts, he was awarded 7th place in the competition.
Development
–Dear reader: A more detailed development analysis of the KV-4 program can be found in the KV-4 Dukhov article–
In early 1941, the Soviets were experimenting with KV-1 based tanks with increased armor and firepower, ranging from the T-150, which was essentially a KV-1 with 90 mm armor, to the KV-220, with 100 mm of armor, the 85 mm F-30 gun, and a longer hull. Other projects included the Object 221 and Object 222. The latter was set to enter mass production in July 1941, under the name KV-3. These tanks were designed and built at the LKZ (Leningrad Kirov Plant), by the SKB-2 design bureau.
Yet in a quick turn of events, on 11 March 1941, the Soviet Intelligence Services passed forward a report on the development of German heavy tanks. The heavy tanks Mark V, Mark VI and Mark VII were mentioned, weighing at 36, 45 and 90 tonnes respectively. The Mark VII, which can be assumed to have been an early proposal of the Pz.Kpfw.VII Löwe, greatly worried the Soviet officials. Aside from its heavy weight and supposedly thick armor, it allegedly was to be armed with a 105 mm gun.
If these German tanks were to become a reality, combined with the increasing threat of German invasion, the Soviets would have no realistic answer. The only true heavy tank in service at the time was the KV-1, and while it was adequately armed and very well protected, its weight, rushed development, and unreliable mechanics would make the KV-1 tank a problematic vehicle during wartime use. The heavier tanks, such as the T-150 and KV-220, relied on many of the KV-1’s components, with thicker armor and larger guns, while still failing to match the theoretical power of the new German heavy tank.
It was clear that a new heavy tank was needed, thus on 21 March, a new heavy tank was ordered to be developed at LKZ. Named KV-4, it was to be armed with the recently developed 107 mm ZiS-6 gun as well as a secondary 45 mm gun, several machine guns and a flamethrower. Armor was to be 130 mm at the front and 120 mm at the sides. Due to these measures, the weight of the tank was expected to be between 70 and 72 tonnes. To power this new heavy tank, a 1,200 hp M-40 aviation diesel engine with four TK-88 turbochargers was used. The SKB-2 design bureau at LKZ was tasked to develop the tank, which received index 224 (Object 224). The project deadline was 17 July.
Shortly thereafter, on 7 April, the heavy tank programs were reconsidered. Firstly, the KV-3 was to become a larger tank, based on the uparmored hull (to 120 mm) of the KV-220, with a new turret and the same 107 mm ZiS-6. The KV-4 was also changed, its side armor was increased to 125 mm, the weight estimate was increased to at least 75 tonnes and other small changes were made. Lastly, the KV-5 (Object 225) was to be designed, with the same 107 mm gun, but with 170 mm of frontal armor on a 100 tonne platform. Furthermore, the deadline for the KV-4 was brought forward to 15 June.
The head of the KV-4 project was head of SKB-2, J.Y. Kotin, but instead of appointing a design team, he would launch a design competition for the SKB-2 engineers. The goal was to incorporate as many original and innovative features as possible, and the best designs would be rewarded financially. With the funding and project approval from LKZ director I.M. Zaltsman, the competition began.
After evaluation, the results of the submitted designs were given on 9 May. Over a dozen different drawings and engineers partook. First place went to N.L. Dukhov, second to the trio of K.I. Kuzmin, V.I. Tarotko and P.S. Taraptatin. Third place went to N.V. Tseits. In total, 11 designs were awarded placements, with 13 designers receiving monetary prizes.
One of these awarded designs was by L.N. Pereverzev, whose design was ranked 7th, alongside the designs of Kalivod and Bykov. As an award for receiving 7th place, Pereverzev received 500 rubles.
L.N. Pereverzev
After graduating from the Military Academy of Mechanization and Motorization of the Red Army in 1939, Leonid Nikolevich Pereverzev started working as a military engineer at the LKZ SKB-2 design bureau. There, he would be involved in most of their projects, with the development of the KV-1, being chief engineer of the KV-150 and the gearbox designer for the KV-220, as well as partaking in the design of the KV-3 and KV-4. However, these would be his last tank design projects. In August of 1941, shortly after the German invasion, Pereverzev would be transferred to the newly formed 22nd PRB (Mobile Repair Battalion) at LKZ. Both he and his unit quickly received recognition for their skill in the repair and maintenance of KV-1 tanks.
By the end of the war, Pereverzev had received the Medal For Military Merit, Medal For Defense of Moscow, Medal For the Capture of Köningsberg, Medal For Victory against Germany in the Great Patriotic War of 1941-1945, Order of the Patriotic War (both I and II Degrees), and Order of the Red Star.
Leonid Nikolevich Pereverzev after the war.
Source: Yuri Pasholok
Design
Of the two dozen KV-4 designs submitted, Pereverzev’s was one of the strangest. The turrets were arranged in a battleship-style layout, consisting of a smaller turret armed with a 45 mm gun in front of the main turret, armed with a 107 mm gun, allowing for good horizontal firing angles for both turrets. The engine, gearbox and final drive were located at the rear. The sprockets were extended far beyond the armored hull, in lightly armored housings, allowing for trench crossing capabilities, a design concept found as early as the British ‘tadpole tail’ found on the First World War Mark IV tank. This design choice allowed for a wider hull with more internal space, but greatly sacrificed the protection of the tracks, which had no cover over them and were susceptible to any kind of enemy fire.
The frontal hull section consisted of two main armor plates that were pressed into shape and welded together. The sides were more peculiar, as no drawings give a clear picture. Only the top cutout view drawing shows that the fighting compartment and fuel tanks were pushed underneath the track returns, protected by thick 125 mm armor. The rear consisted of the standard KV-style armor plates with room for air circulation for the cooling system.
Side cutout view of Pereverzev’s proposal, showing the track return riding over the hull, on small rollers. Note that the top machine gun turret had faded out.
Source: ASKM Top cutout view of Pereverzev’s KV-4. On the top track, the sponson and subsequent sideskirts can be seen. Fuel and ammunition was stored here.
Source: TsAMO
The tank was to be powered by a 1,200 hp M-40 aviation engine, which could run on both diesel and kerosene, and was boosted with four TK-88 turbochargers. The fuel tanks were mounted in the sides of the hull, and provided the tank with an estimated range of 15 hours of operation or 300 km. Its estimated top speed was 38 km/h.
Turrets
Like most KV-4 designs, Pereverzev opted for two turrets in a battleship-style configuration, with the smaller turret at the front, and the larger one on an elevated platform, allowing both to fire forwards without interfering with each other. Additionally, the main turret was mounted back far enough to provide a greater field of fire for the front turret.
One of the drawings also showcases two different turret designs, one with and the other without a turret bustle. A few other differences were made as well, like the removal of the rear-facing DT machine gun for more ammunition space in the turret bustle, and a new turret front armor plate construction.
The two different turret designs, the one on top showing a larger turret bustle and one-piece frontal section. The lower turret is shorter, and features a DT machine gun. Source: Stalin Supertanks IS-7
Crew
The crew was to be 7 men, consisting of the commander, 2 gunners, 3 loaders (1 for the secondary gun and 2 for the main gun) and driver.
The gunner sat to the left of the gun, and would fire the 107 mm gun. His vision was only provided by the main gun’s sight, as no other periscopes are drawn. The commander was seated behind him, and would operate the small rotating cupola, armed with a DT machine gun. Similarly, no periscopes are drawn in the blueprints, so his vision likely consisted of slits within the cupola. One of the main gun loaders sat to the right of the gun. In the turret variant without the turret bustle, he would also fire the rear-facing machine gun. The other loader likely sat in the hull, underneath the turret, and lifted the 107 mm shells to the other loader.
The driver sat in the front of the hull, in a station akin to the one on the KV-1. Behind him were the gunner and loader for the secondary turret.
Armor
Protection consisted of armor ranging from 105 mm to 125 mm on the hull, with the exception of the hull belly and decks, which were 40 mm and 50 mm respectively. The main turret had a 125 mm frontal plate, with the 125 mm thick mantlet taking up large amounts of space for extra armor. Sides and rear were 140 to 150 mm thick. The secondary turret had just 60 mm of armor at the front, due to the space constraints, but the sides and rear were 125 mm thick. The large size combined with the thick armor of the tank would have pushed its total weight to 100 tonnes.
Estimated armored thickness on Pereverzev’s KV-4, short variant turret.
Source: Zinoviy Alexeev
Armament
The main armament consisted of the powerful 107 mm ZiS-6 (F-42) cannon, developed by V.G. Grabin at Plant No.92 for such heavy tanks, and was the main armament on all KV-4 designs. It had a muzzle velocity of 800 to 840 m/s and used an 18.8 kg shell, penetrating 115 mm of armor at 1,000 meters (calculated ballistics). In total, 108 rounds of 107 mm ammunition were provided.
Secondary armament consisted of the classic 45 mm 20-K mod.1937 gun, fitted on most Soviet light tanks at the time, and was a great complementary weapon, and still potent by 1941 against soft-skin targets. For the secondary gun, 195 rounds were provided.
Additionally, three (two for the turret-bustle variant) DT 7.62 machine guns were mounted, one coaxially with the 45 mm gun, one in the commander’s cupola and one at the rear of the main turret. In total, 3,000 rounds were given, in drum magazines.
The blueprints also mention a flamethrower with 100 liters of fuel, but where it was positioned is unclear.
Start of the war
After the competition results were announced in May 1941, progress on the KV-4 stagnated, focus shifting to the KV-5. The Axis’ invasion of the Soviet Union on 22 June 1941 further slowed down the development, as LKZ’s focus shifted to increasing production of the KV-1. The final nail in the coffin for the KV-4 and KV-5 came when the German troops were approaching the city of Leningrad, home of the LKZ plant. The SKB-2 design bureau had to be evacuated to ChTZ in Chelyabinsk, and the KV-4 and KV-5 projects were never continued, considering that the alleged German super heavy tank never appeared and the resources were better spent on more rational tasks.
Conclusion
Pereverzev’s expertise in tank design and as a military engineer was shown in his proposal for the KV-4 tank program, with several unusual features, such as the track running over the entire hull for more internal space and the extended sprocket for better trench crossing capabilities, as well as seeing the advantages of a turret bustle. For these attributes, his design was awarded 7th place in the design competition, but would not lead to any further work.
KV-4 Pereverzev variant with a shorter turret. Illustration by Pavel Alexe.KV-4 Pereverzev variant with a bustle turret. Illustration by Pavel Alexe.
KV-4 Pereverzev Specifications
Dimensions (L-W-H) (approx.)
9.5 x 3.8 x 3.82 m
Total weight, battle-ready
100 tonnes
Crew
7 (commander, main gunner, 2x main loaders, driver, secondary gunner, secondary loader)
Propulsion
1,200 hp diesel V-12 M-40 with 4 TK-88 turbochargers
Speed
38 km/h (hypothetical)
Suspension
Torsion bar, 8 wheels per side
Armament
107 mm ZiS-6 (F-42)
45 mm 20-K
2-3x DT 7.62 mm machine guns
Flamethrower (100 liters)
Armor
Turret: 140 mm
Hull: 100-125 mm UFP
105 mm LFP
105-125 mm sides and rear
Top: 50 mm
Belly; 40 mm
KV-4 Ermolaev variant with 2 turret. Illustration by Pavel Alexe.
Soviet Union (1941)
Super Heavy Tank – Blueprints Only
During the spring of 1941, the Soviet SKB-2 heavy tank bureau was working on various types of heavy tanks, ranging from the uparmored KV-1, the T-150, to the super heavy KV-4 and KV-5 tanks. The development of the KV-4 entailed a new philosophy in which engineers would propose independent designs, in an attempt to bring out as many innovative features as possible. One of these designers was A.S. Ermolaev, who designed two KV-4 variants, one “standard” layout, weighing 90 tonnes, and one with a secondary turret, weighing 95 tonnes.
Development
–Dear reader: A more detailed development analysis of the KV-4 program can be found in the KV-4 Dukhov article–
The Soviet heavy tank project named KV-4, also known as Object 224, was developed during the early months of 1941. The development of the tank was triggered by a letter sent by the Soviet Intelligence services to the Soviet Main Directorate of Armed Forces (GABTU) in March 1941. The letter discussed the development of German tanks, including a 90-tonne heavy tank armed with a 105 mm gun. Realizing how far behind their heavy tank development was, the Soviets urgently began the development of a new heavy tank.
The Kirov Leningrad Plant (LKZ) and its SKB-2 design bureau were responsible for the development of the KV-4. LKZ had previously designed the KV-1, which was the only somewhat capable heavy tank in service at the time. However, the KV-1 proved to be unreliable, slow, and heavy during the war. LKZ had also designed several heavy tanks parallel to the KV-1 or as direct developments of it, such as the T-150, KV-220, and KV-3. The KV-220, in particular, was a capable design, comparable to the later German Tiger I heavy tank. It weighed 62.7 tonnes and was armed with an 85 mm F-30 gun, but it was cumbersome and unreliable during trials.
The KV-4 was requested to be a 70-tonne tank armed with the 107 mm ZiS-6 gun, a 45 mm Model 1937 or 1938 as a secondary gun, 3 DT 7.62 machine guns, and a flamethrower. The tank’s armor was to be 130 mm at the front and 120 mm at the sides. The tank was to be powered by a massive 12-cylinder M-40 engine with 4 TK-88 turbochargers that outputted 1,200 hp and had a displacement of 61 liters. The tank’s crew should have consisted of 6 members. The GABTU released the specifications for the tank just 10 days after receiving the letter, and the project deadline was set to 17 July. Plant No.92 was to build the guns by 1 September, and the Izhora plant was to finish the turret and hull by 1 October.
On 7 April, just 17 days later, the GABTU requested that the KV-4’s specifications be increased to 75 tonnes in weight and have armor improvements to 125 mm at the sides and rear. The deadline was also tightened to 15 June. In the same letter, the GABTU requested an even heavier vehicle, the KV-5, with 170 mm at the front and 150 mm at the rear, and a weight of 90 tonnes. Stalin’s personal involvement in the heavy tank projects and the sudden changes in design and increased time pressure would speed up the design process. The previously designed KV-3 was also given improved parameters, up to 68 tonnes, and armed with the same ZiS-6 107 mm gun as on the heavier tanks, with the purpose of acting as a stopgap tank.
To speed up the development of the KV-4, the SKB-2 design bureau head, J.Y. Kotin, set up a design competition. The competition was to gather as many diverse and revolutionary design elements as possible, and the top places were awarded financial rewards. Over 27 designs were presented by the SKB-2 bureau, and the first place was awarded to N.L. Dukhov, who presented an enlarged KV-220. Second place originally went to K.I. Kuzmin, V.I. Tarotko and P.S. Tarapatin, but were later disqualified because of the turretless design, and N.V. Tseits’ design (who was initially awarded third place) came second.
Ermolaev’s expertise in tank design and influence at SKB-2 landed his proposal in fourth place alongside Sychev’s design. For this achievement, he received 2,000 rubles.
A.S. Ermolaev
Born in the village of Kliny, Kaluga Oblast, in 1904, Afanasy Semyonovich Ermolaev would begin studying at the Military Academy of Mechanization and Motorization of the Red Army in 1932 and graduate two years later. He would then begin work at the SKB-2 design bureau at LKZ, working on the development of the T-28, SMK and KV-1. During the war, he would continue designing under Kotin’s leadership, working on the KV-1S, KV-85, IS, IS-2, SU-152, ISU-152 and ISU-122S. Post war, he would continue his activities at ChKZ in Chelyabinsk, working on several tanks, most notably the T-10, but also agricultural tractors K-700 and S-80.
He would receive 2x Order of Lenin, 2x Order of Kutuzov (1st and 2nd deg.), 2x Stalin Prize (1st and 2nd deg.), Order of the Red Banner of Labour, Order of the October Revolution, Medal “For the Victory over Germany in the Great Patriotic War 1941.1945” and the Medal “For the Defense of Leningrad”.
Afanasy Semyonovich Ermolaev after the war.
Source: Famhist.ru
Design
Unlike most other designers, Ermolaev presented two variants for his entry, a traditional layout tank with one large central turret, and a longer tank with two smaller turrets.
Between the two variants, the hull was mostly identical. Following the general shape and layout of previous KV designs, the front featured a stepped plate which was pressed into shape, while the sides were completely flat. One difference was that the rear air cooling hole was protected by a flat armor plate instead of a curved one.
The main difference between the hulls of the two variants was the length, one was 8.22 meters long, while the other reached 8.52 meters, in order to fit the secondary turret. Both hulls had the same amount of roadwheels, but they were closer spaced on the shorter variant. Due to the various differences between the two, weight would also become a variable factor, with the single turret version weighing 90 tonnes, while the other weighed 95 tonnes.The main turret on both variants was remarkably similar, the only difference being the lack of a turret bustle on the two-turret variant. Otherwise, the turret was a hexagonal shape, made out of four different plates, where the side walls were stamped in shape. A large non-rotating cupola with six periscopes was located at the back of the turret and was used by the commander. No other details are shown regarding the turret.
Both variants were equipped with the 107 mm ZiS-6 and 45 mm 20-K mod.1937 guns, however they each were in their own individual turrets on the two-turret variant (the secondary turret had 270° rotation while the main full 360°), and mounted coaxially in the single-turret variant.
The variant with a single turret, which featured the 107 mm ZiS-6 and 45 mm 20-K mounted coaxially.
Source: ASKM The variant with 2 turrets, where the smaller turret was mounted in front of the main turret.
Source: ASKM
The tank was powered by the M-40 1,200 hp aviation engine, capable of running on both diesel and kerosene. It was boosted by four TK-88 turbochargers. Fuel tanks were placed on the side walls. It was estimated that the tank could (optimistically) reach 40 to 45 km/h.
Crew
The single turret variant had a crew of 6 men; commander, gunner, 2x loaders, driver, and radio operator. The gunner sat to the left of the main gun, and operated both the 107 mm gun and 45 mm gun, which was mounted coaxially. The commander sat behind him, in an elevated position, with his head in the cupola, from where he could acquire targets and easily inform the gunner. The two loaders both sat on the right side of the gun, one tasked with loading the 107 mm gun and the other the 45 mm gun. The driver sat in the hull, in the center, with an emergency escape hatch in the floor, to his right. The position of the radio operator is unclear.
For the two-turret variant, the main gunner and commander had the same positions, while the two designated loaders for the main 107 mm gun sat on the right side of the gun, one loading the shells in the gun and the other lifting them from the hull stowage boxes.
The driver was also in the front of the hull, but seated to the extreme left side, to make space for the secondary turret, where the secondary gunner and loader worked. Also in the front of the hull, underneath the secondary turret. was a flamethrower of unspecified type. The position of the radio operator is, once again, unclear.
Armor
The hull consisted of 130 mm of frontal armor plates, while the sides and rear were 125 mm thick. The belly and roof were 50 mm thick. The front of the turret consisted of a 130 mm plate angled at 60° from horizontal, for a relative thickness of 150 mm. The sides and rear of the turret were also 125 mm thick.
Armament
Like on most other KV-4 designs, the main gun was the 107 mm ZiS-6 (F-42) developed by V.G. Grabin at Plant No.92 from autumn 1940 to spring 1941, and was later tested on a KV-2 in June 1941. It was a potent anti-tank cannon, with a muzzle velocity of 800 to 840 m/s and a shell weight of 18.8 kg, with a calculated penetration of 115 mm of armor at 1,000 meters. The main gun had +20° elevation and -5° depression (same applies for the 45 mm coaxial). The 45 mm in the secondary turret variant had +25° elevation and -5° depression.
The 45 mm 20-K mod.1937 was still widely used on Soviet tanks at the time, but by 1941, its anti-tank capabilities were lackluster. However, it still provided good performance against soft-skin targets.
For defense against infantry, a 7.62 mm DT machine gun was placed in a ball mount in the rear of the turret, but the two-turret variant had an additional coaxial DT machine gun. The two-turret variant also featured an unspecified type of flamethrower in the front of the hull, to be operated by the driver or secondary gunner.
Discontinuation of the project
After the announcement of the competition results, the KV-4 project stagnated, with SKB-2 focusing on the KV-3 and KV-5. Progress on these heavy tank projects was further halted by the start of the war on 22 June, as the LKZ factory shifted focus to the production and repair of KV-1 tanks.
The situation would turn grave when German forces were approaching the city of Leningrad, home of the LKZ plant. In September, the SKB-2 design bureau was moved to ChTZ to continue work. However, with this move, the KV-4 and KV-5 projects were not reconsidered and canceled. Only the KV-3 project remained active, but with focus on improving the KV-1 tank, no progress was made on the KV-3 either and it was canceled by 1942.
Conclusion
The rational and conventional KV-4 design presented by A.S. Ermolaev offered a realistic alternative to the more unorthodox designs, landing him the fourth spot in the competition. Still, the high crew number and excessive weight, especially for the two-turret variant, could have proven problematic. The entire project was deemed expensive and irrelevant to the military needs of the Soviet military, even by its own designers. Once abandoned following the SKB-2’s move to ChTZ, the project was forgotten.
KV-4 Ermolaev variant with 2 turrets. Illustration by Pavel Alexe.KV-4 Ermolaev variant with a single turret. Illustration by Pavel Alexe.
KV-4 Ermolaev Specifications
Variant
1 Turret
2 Turrets
Dimensions (L-W-H)
8.22 x 4 x 3.25 m
8.52 x 4.00 x 3.25 m
Total weight, battle-ready
90 tonnes
95 tonnes
Crew
6 men (commander, gunner, 2x loaders, driver, radio operator)
8 men (commander, main gunner, 2x main gun loaders, driver, secondary gunner, secondary loader, radio operator)
Propulsion
1,200 hp diesel V-12 M-40 with 4 TK-88 turbochargers
Speed
40-45 km/h (hypothetical)
Armament
107 mm ZiS-6 (F-42)
45 mm 20-K (?)
7.62 DT machine gun
107 mm ZiS-6 (F-42)
45 mm 20-K
2x 7.62 DT machine gun
Flamethrower
Armor
Turret: 125-130 mm
Hull: 125-130 mm
Top: 50 mm
Belly: 50 mm
Marishkin's KV-4 design. Illustration by Pavel Alexe.
Soviet Union (1941)
Super Heavy Tank – Blueprints Only
The KV-4 program was started in March 1941 to deal with alleged new heavy tank advances by the German Reich. Development took place at the Leningrad Kirov Factory design bureau SKB-2 headed by J.Y. Kotin. A design competition was held, with over 27 different design proposals. While many designs were appreciated for their innovative features, even more were disregarded. One of these was proposed by engineer F.A. Marishkin, who’s design featured a large complex turret and an unremarkable hull.
Development
–Dear reader: A more detailed development analysis of the KV-4 program can be found in the KV-4 Dukhov article–
107 mm ZiS-6 (F-42)
45 mm Mod.1937 20-K (hull-mounted)
3x 7.62 mm DT machine guns
6
50 km/h
Turret: 130 mm
Hull: 130 mm
Belly and belly: 50 – 40 mm
N/A
Marishkin KV-4
86.4
8.7
3.6
3.5
107 mm ZiS-6
45 mm 20-K
7
40 km/h
Front: 130 mm
Upper frontal: 80 mm
N/A
Pavlov & Grigorev KV-4
91
8.5
4.0
3.6
107 mm ZiS-6
45 mm 20-K
6
45 km/h
Front: 100 – 125 mm
N/A
Turchaninov KV-4
89.5
9.8
4.0
3.0
107 mm ZiS-6
45 mm 20-K
DT machine gun
7
35 km/h
Front: 125 mm
N/A
Strukov KV-4
92
8.6
4.0
3.8
107 mm ZiS-6
45 mm 20-K
6
50 km/h
Front: 80 – 130 mm
N/A
Unknown KV-4
N/A
Unknown KV-4
With the expansion of German aggression over Europe in 1940, Soviet leadership followed events with unease, despite their non-aggression pact with the German Reich, signed in August 1939. Their successful use of tanks was unprecedented and other nations rushed to expand their tank development and armament programs. During this time, the Soviets would start fielding the KV-1 heavy tank, based on experiences from the Winter War. However, it would quickly become apparent that it was rushed due to Stalin’s requests and still needed plenty of fine tuning. By the start of Operation Barbarossa, the KV-1 would still prove a lethal weapon, with excellent protection and adequate firepower, but was let down by significant quality, logistical and training problems.
On 11 March 1941, the Soviet Intelligence services submitted a report to the GABTU (Main Directorate of Armored Forces) regarding the development of German tanks. Most noticeable was the section on heavy tanks, where, amongst others developments akin to the VK.30.01(H) and VK.36.01(H), was the mention of a 90 tonne Mark VII tank, armed with a 105 mm gun, which is know now was some early variant of the later Pz.Kpfw.VII Löwe. This came as an unpleasant surprise to Soviet officials, who only had the aforementioned KV-1 and the hopelessly obsolete T-35 tank. The most advanced heavy tanks in development were the KV-150 (T-150), an improvement based on the KV-1 with 90 mm of frontal turret armor and total weight of 50 tonnes, and the KV-220, armed with an 85 mm F-30 gun, 100 mm of armor all-round, and total weight of over 60 tonnes. While both were very respectable on paper and superior to all German tanks of the time, they had reliability issues, with the KV-220 breaking two engines while testing, though the engine was equally unreliable and only two were built.
Thus, the GABTU set out to develop a new heavy tank to match the German tanks. On 21 March, they laid out all the requirements for the new heavy tank. It was to be armed with the new 107 mm ZiS-6 developed at Factory No.92 by V.G. Grabin. The armor was to be 130 mm to 120 mm all-round and a weight between 70 to 72 tonnes. Propulsion was set to be the M-40 diesel aviation engine with 4 TK-88 turbochargers. The tank was to be equipped with a vast array of secondary weapons as well, namely a 45 mm gun and at least three 7.62 mm machine guns, as well as a flamethrower.
Development of the KV-4 would take place at the LKZ (Kirov Leningrad Factory) SKB-2 design bureau, the same office responsible for all the previous KV tanks. Production of the first prototype was assigned to the Izhora plant, based on LKZ drawings. Thus, the tank was named KV-4 and received index Object 224. The project deadline was set to 17 July for the drawings and October for first prototype production.
Shortly after the initial release of the requirements, the GABTU edited their request, specifically on 7 April. Firstly, they would request a heavy upgrade of the KV-220, named KV-3, that would act as a stopgap until the heavier tanks were ready, armed with a 107 mm gun and 120 mm of frontal armor. Likewise, an even heavier tank was requested, named KV-5, with frontal armor thickness of 170 mm and side of 150 mm, and weight of at least 90 tonnes, also armed with the 107 mm ZiS-6. To better fit the KV-4 between the two new vehicles, its weight threshold was lifted to at least 75 tonnes, and 125 mm of armor at the sides. To increase the urgency of the matter, the deadline was tightened to 15 June.
Over at SKB-2 design bureau, which was headed by J.Y. Kotin, work would set on developing all 3 tanks. Interestingly, as a result of the loose requirements set by the military, Kotin would challenge his engineers to a design competition, in an attempt to bring out the most innovative ideas. With the approval of the factory director, I.M. Saltzman, Kotin was given the necessary funds to award the top designers with significant financial awards. Over 24 designers entered the competition, with just as many different concepts submitted. On the 9 May, the winners were announced, in first place being N.L. Dukhov, a trio of designers, K.I. Kuzmin, P.S. Tarapatin and V. I. Tarotko in second place and N.V. Tseits on third. In total, 11 designs and 13 engineers were awarded.
However after the competition was over, work on the KV-4 severely stagnated, to the point where Marshal of the Soviet Union G.I. Kulik had to personally come over and attempt to speed up the process, to no avail. Truth is, most of the efforts went to the KV-5, based on knowledge from the KV-4. Even so, the KV-5 was in a very early stage when the German Reich began their invasion of the Soviet Union, on 22 June 1941, and their quick advance into Soviet territory would put great strain on tank factories.
By September, the German forces were advancing towards Leningrad, and the SKB-2 design bureau was evacuated to ChTZ (Chelyabinsk Tractor Plant), which was renamed ChKZ (Chelyabinsk Kirov Plant), or as more commonly known, Tankograd. Unfortunately for the heavy KV designs, they were seen as a massive resource drain and work on them did not recommence.
F.A. Marishkin
Alongside 5 other engineers, F.A. Marishkin was head of the design of the transmission of the KV-1 while also being part of the design team of the SMK and T-150. After the war, he would continue working at the Kirov plant as one of the designers of the KT-12 forestry tractor, but also on the development stages of the T-10. F.A. Marishkin after the war
Source: Constructor of Combat Vehicles
Design
Compared to the majority of the KV-4 designs presented, Marishkin’s can be seen as one of the more conservative ones in regards to general layout and design. What was essentially an enlarged KV-220 hull was mated to a very large main turret, with a secondary turret on top. The front of the hull was a ‘stepped’ design, consisting of a large lower plate, a steeply angled ‘hood’ followed by a flatter but thickened section in the armor connecting to the hull roof. The side armor was simply flat all along. The rear was very similar to the KV-1, consisting of two plates with a gap in between for engine cooling airflow. The main turret was mounted between the second and sixth roadwheels. Frontally, it consisted of a single plate stamped into a curved shape. The sides of the turret are not specifically drawn out on the blueprints, but they curved inwards at the rear, as well as being angled upwards for improved protection.
Perhaps the only unusual aspect of Marishkin’s design was the secondary turret, specifically its placement. It was towards the rear of the turret and offset to the right. As the main turret was curved and angled inwards, the secondary turret hung over the main turret walls, requiring a form of extension of the turret walls to support the turret ring. This certainly complicated the construction process. Side cutout view of the KV-4 proposed by Marishkin.
Source: ASKM
The recoil distance of the ZiS-6 107 mm gun was not specified, but it is clear that, if the secondary turret was placed centrally, the gun recoil would slice the secondary turret gunner’s legs off (see KV-4 Kruchenykh). The only other option would have been extending the turret’s bustle size, but that might have not been possible considering balance and the limited turret ring size.
Top view of the hull, showing the different fuel tanks on the sidewalls and floor, engine, and final drive. Of significant interest are the two circles in the center, the big one representing the main turret ring, and the smaller one, the secondary turret.
Source: ASKM
The engine used was a M-40 1,200 hp engine, originating from an aviation engine and capable of running on both diesel and kerosene. It had a V12 configuration, 61.07 liters displacement, and featured 4 TK-88 turbochargers. Fuel tanks were fitted alongside the hull sides and floor, underneath the turret.
Side cutout view of the hull layout, with a cross section of the M-40 engine and fuel tanks. The armor is not shown.
Source: ASKM
The suspension was a standard KV series layout, with 8 steel-rimmed roadwheels sprung by torsion bars and with travel stops. The drive sprocket was at the back, connected to the brakes and final drive ensemble.
Crew
The crew on Marishkin’s proposal was 7, one more than the GABTU-specified 6. The exact layout and positions are unknown, but based on the tank layout and similar designs, the following can be concluded. The crew consisted of the driver, radio operator, main gunner, 2 main gun loaders, commander (which was also the secondary armament gunner), and secondary loader.
The driver would be seated (as seen in the drawing above) in the front of the hull. Next to him would be the operator of the 10-R tank radio.
The remaining 5 crewmembers would be seated in the turret. The main gunner was seated to the left of the gun, with a loader behind him. The other main loader was likely on the opposite side, to the right of the gun breech. The commander was seated to the left of the 45 mm secondary gun and the loader to the right.
This layout is purely speculation by the author, largely based on space, practicality, and other KV-4 designs with known crew positions. It could be argued that certain positions did not exist or should be rearranged, for example, the second main loader replaced with the tank commander and the secondary gun to receive its own designated gunner.
Armor
Like most of the pre-war Soviet heavy tanks, the armored plates were simply welded together without interlocking. A likely form of connection for the heavier plates was via pins, like on the German Maus tank. These would physically improve the connection between plates but could prove to further complicate the manufacturing process and cause weakening of the armor in those areas to be more susceptible to cracking and shattering.
The lower frontal plate was 130 mm thick, pressed into shape. The upper part of the armor consisted of a single plate, with the bottom being 80 mm thick and the top part 130 mm, pressed to form a steep hood and driver’s front plate. The side was a single flat 120 mm thick plate. The turret consisted of a single frontal plate, 130 mm thick, pressed into shape. The side armor is more speculative due to the lack of drawings, but would also have followed a similar process, albeit with a 125 mm thick plate.
Armament
The main weapon used on all KV-4 designs was the 107 mm ZiS-6 developed a few months earlier by Factory No.92 by V.G. Grabin by own initiative. With 800 to 840 m/s muzzle velocity and a 18.8 kg shell, it was a very potent anti-tank weapon, capable of penetrating 115 mm of armor at 1,000 m. The gun was tested in June and July on a KV-2 testbed and would enter production a few months later. However due to the KV-4 and subsequently KV-3 and KV-5 tanks never being built, the half-built guns had to be melted and recycled.
Secondary armament consisted of the 45 mm 20-K gun, used on the majority of Soviet light tanks at the time, as well as at least two 7.62 DT machine guns.
The KV-2 testbed with the 107 mm ZiS-6 gun, June 1941.
Source: Warspot
Death of LKZ’s Heavy Tanks
The Axis forces made quick progress into Soviet territory and by August were already approaching the city of Leningrad. To avoid capture and disruption of developments, many of the engineers of the SKB-2 design bureau were relocated to the Chelyabinsk Tractor Plant (ChTZ), which was renamed to Chelyabinsk Kirov Plant (ChKZ) upon their arrival. However, it was clear that the heavy tank developments in the form of the KV-3, KV-4, and KV-5 were more resource and financial pits for the Soviet defense than any actual help. The projects were all abandoned and development switched to improving the KV-1, which resulted in new successful vehicles, such as the KV-1S.
Conclusion
While, with hindsight, the entire KV-4 program ended up being a massive waste of resources, it is clear that some designs were fundamentally better than others, like the winning design by N.L. Dukhov. In contrast, the design by Marishkin was not particularly original and was not deemed as effective considering the liberal requirements and effective armament. Even today, his design is one of the lesser known and least appreciated designs from the program.
Marishkin’s KV-4 design. Illustration by Pavel Alexe.
KV-4 (Object 223) Marishkin specifications
Dimensions (L-W-H)
8.7 – 3.8 – 3.5 m
Total Weight, Battle Ready
86.4 tonnes
Crew
7
Propulsion
1,200 hp diesel V-12 M-40 with 4 turbochargers
Speed
40 km/h (hypothetical)
Armament
107 mm ZiS-6
45 mm 20-K
>2 DT 7.62 machine guns
Armor
Turret: 130 mm
Frontal upper hull: 80 mm
Frontal lower hull: 130 mm
Side hull: 125 mm
Rear hull: 125 mm
Top: 40-50 mm
Belly:40-50 mm
Total Production
0; blueprints only
Sources:
Breakthrough tank KV – Maxim Kolomiets
Stalin’s Supertanks IS-7 – Maxim Kolomiets
KV 163 1939-1941 – Maxim Kolomiets
Confrontation – Ibragimov Danyial Sabirovich
Constructor of Combat Vehicles – N.Popov
Bronevoy Schit Stalina. Istoriya Sovetskogo Tanka (1937-1943) M. Svirin
About the forgotten creators of Soviet armored power. (historyntagil.ru) – S.I. Pudovkin
German Lion | Warspot.ru – Yuri Pasholok
Крупный калибр для крупных КВ | Юрий Пашолок | Дзен (dzen.ru) – Yuri Pasholok
Tank building on the verge of common sense | Warspot.ru – Yuri Pasholok
Large caliber for large HF | Yuriy Pasholok | Yandex Zen – Yuri Pasholok
Tank Archives: Soviet 107 mm Guns – Peter Samsonov
Tank Archives: KV-3 Mulligan – Peter Samsonov
Tank Archives: Heavy Tank Costs – Peter Samsonov
Tank Archives: ZIS-6 Characteristics – Peter Samsonov
Marishkin F.A. (famhist.ru)
KV-4 as designed by Sychev. illustration by Pavel Alexe, funded through our Patreon campaign.
Soviet Union (1941)
Super Heavy Tank – Blueprints Only
A few months before the German invasion of the USSR, the Soviets were working on developing massive heavy tanks. One of these programs was the KV-4 projects, which included 27 different proposals. One of these was from LKZ engineer L.E. Sychev. Instead of focusing on revolutionary and unique features, he built upon and perfected the concept already tested on the SMK heavy tank. These efforts placed his design in 4th place in the KV-4 design competition.
Development
–Dear reader: A more detailed development analysis of the KV-4 program can be found in the KV-4 Dukhov article–
In March 1941, the Soviet Intelligence services sent a letter to the Soviet Main Directorate of Armed Forces (GABTU) discussing the development of German tanks. Here, a 90 tonne heavy tank was described, armed with a 105 mm gun. Yet, only by November 1941, the first mentions of a tank fitting this description appeared, the Pz.Kpfw. VII, or Löwe. Understanding how far behind their heavy tank development was, the Soviets set about the urgent development of a new heavy tank.
Development of the new beast became the responsibility of the Kirov Leningrad Plant (LKZ) and its SKB-2 design bureau. The bureau had already designed the only somewhat capable heavy tank in service, the KV-1, however, it proved to be unreliable, slow, and heavy once war commenced. Up until that point, LKZ had also designed several heavy tanks in parallel with the KV-1 or as a direct development from it, such as the T-150, KV-220, and KV-3. With hindsight, the KV-220 was a genuinely capable design, comparable to the later German Tiger I heavy tank. It weighed 62.7 tonnes and was armed with an 85 mm F-30 gun. On the other hand, during trials, it was cumbersome and unreliable, breaking 2 engines.
The new heavy tank to be designed by LKZ was given the designation KV-4 or Object 224. Just 10 days after the original letter was sent, on 21 March, the GABTU had released the specifications for the technical capabilities of the tank. It was to be a 70-tonne tank, armed with the 107 mm ZiS-6 gun in, a 45 mm Model 1937 or 1938 as a secondary gun, 3 DT 7.62 machine guns, and a flamethrower. Armor was to be 130 mm at the front and 120 mm at the sides. Propulsion was provided by a massive 12 cylinder M-40 engine with 4 TK-88 turbochargers, outputting 1,200 hp with a displacement of 61 liters. The crew was to be of 6. Just 6 days later, the project deadline was set to 17 July. Subsequently, based on the LKZ blueprints, Plant No.92 was to build the guns by 1 September and the Izhora plant was to finish the turret and hull by 1 October.
Just 17 days later, on 7 April, the GABTU requested the KV-4 specifications be increased to 75 tonnes weight and armor improvements to 125 mm at the sides and rear. The deadline was also tightened to 15 June. In the same letter, the GABTU requested an even heavier vehicle, the KV-5, with 170 mm at the front and 150 mm at the rear, and weight of 90 tonnes. The sudden changes in design, and the increased time pressure, combined with Stalin’s personal involvement in the heavy tank projects would hurry up the design process. Lastly, the previously designed KV-3 would receive improved parameters, up to 68 tonnes and arming it with the same ZiS-6 107 mm gun as on the heavier tanks, with the purpose of acting as a stopgap tank.
Due to the urgent nature of the project, LKZ began work on the heavy tanks on 10 April. The SKB-2 design bureau headed by J.Y. Kotin was put in charge of their development. Yet instead of pursuing a traditional development path, Kotin, with the approval and funds allocation from factory director I.M. Zaltsman, would set up a design competition for the KV-4. The idea behind this was to gather as diverse and revolutionary design elements as possible. To further encourage this, the competition results would be ranked and the top places awarded financial rewards. By 9 May, the competition was over and over 27 designs were presented by the SKB-2 bureau. First place was awarded to N.L. Dukhov, who designed an enlarged KV-220 with an automated loader aiding system. He received 3,000 rubles. To put this in context, a frontline soldier received 500 rubles for destroying an enemy tank. Second place went to a trio of engineers, K.I. Kuzmin, P.S. Tarapatin and V.I. Tarotko, who together designed a variant with a sponson mounted main gun and secondary gun mounted in a small turret on top. They were awarded 3,000 rubles to split, however their design would be disqualified later because the main gun had limited traverse. Third place went to senior engineer N.V. Tseits, who designed a tank with a very low hull at the expense of a very large turret. He received 2,800 rubles. Due to the disqualification of the second place contender, Tseits’ design would later be selected as the basis for the KV-5. In total, 11 designs were awarded funds. The design by L.E. Sychev was appreciated due to the well-thought-out layout and origins from a trialed tank, the SMK. Thus he was given 4th place in the competition and awarded with 2,000 rubles.
The SMK multi-turreted tank, likely a source for Sychev’s KV-4.
Source: Drikus club
L.E. Sychev
Born in 1913 in, what was at the time St. Petersburg, Leonid Efimovich Sychev undertook his bachelors project at the SKB-2 design bureau at LKZ while studying at the Leningrad Polytechnic Institute in 1932. Just 2 years later, he graduated, and in 1935, started work at SKB-2. He worked on the T-28 and later SMK. As for the KV-1, he first refined the torsion bar suspension alongside N.V. Tseits and G.A. Seregin. Later, he was appointed chief designer for the KV-1 and became the SKB-2’s chief designer of armament in 1940. He was chief designer of the KV-220 and initially, he was also to be chief designer for the KV-3, but was replaced by B. P. Pavlov. After the outbreak of the war, he also worked on improving the T-34, alongside A.A. Morozov. He was awarded the Order of the Red Star, among many others.
Leonid Efimovich Sychev likely after the war.
Source: Museum of SPbPU
Design
As with a handful of other KV-4 designs, Sychev heavily inspired his tank layout upon that of the SMK heavy tank, designed by the same bureau just a few years prior. It featured a long hull, with a steeply angled frontal armor plate. Likewise, the engine was mounted in an upwards rising deck plate. Like on the previous SMK and T-100, a smaller turret armed with the 20-K 45 mm gun was mounted towards the front of the hull and slightly offset to the right, while a larger turret, armed with the 107 ZiS-6 gun was mounted centrally. On top of the main turret was an additional fully rotating commander cupola, armed with a 7.62 DT machine gun. An additional DT machine gun was mounted coaxially in the secondary turret.
As required by the state, the KV-4 featured a 1,200 hp V-2SN diesel engine with 4 turbochargers. According to Sychev, it was enough to allow the 95 to 100 tonne tank to reach top speeds between 40 and 45 km/h, though that is extremely optimistic. The entire powerpack ensemble was situated in the rear and featured an ingenious air intake and cooling system, using overlapping armor plates to prevent entry of shrapnel and debris. The fuel tanks were positioned in the sides of the hull.
Side cutout view of Sychev’s KV-4 proposal. Note the steeply angled frontal hull.
Source: ASKM Partial top view of Sychev’s KV-4. While the drawing provides excellent view and understanding of the hull, the turrets only have their outlines drawn in.
Source: ASKM
Crew
Similarly to the SMK, Sychev’s KV-4 had a crew of 8: commander, main gunner, main loader, turret mechanic/loader assistant, driver, radio operator, secondary gunner, and secondary loader. To further complicate the topic, the exact positions and roles of the crew were never specified or detailed. This leaves a lot of room for interpretation and guesswork based on other KV-4 designs and previous similar tanks, such as the SMK and T-100.
The main turret housed 4 crew members. The main gunner sat to the left of the main gun, and used his main gun sight for vision, though it is likely he would have received his own periscope. The exact position of the tank commander is unknown, though he would have sat on either side of the gun. His head would be inside the main rotating cupola, giving him a commanding view of the battlefield (at 4 m), as well as the ability to independently engage infantry and suppressive fire. The main gun loader would have stood on one side of the gun. He only had 4 rounds in the turret bustle before he would require assistance from the additional loader, standing underneath the turret ring, feeding him shells stowed in the hull.
Towards the bow of the hull sat the driver, to the left side of the hull. Stored to his right was the 20-K 45 mm secondary gun ammunition. Right behind him was the 10-R radio and the radio operator, whose round seat can be seen in the blueprint. The secondary gunner and loader sat in the additional turret, though they were able to have direct communication with both the driver and radio operator.
Armor
All KV-4 designs had more or less the same armor thicknesses all around, i.e. 130 mm at the front and 125 mm at the side and rear. Nonetheless, the layout and angling of these plates varied widely. Unlike previous LKZ heavy tank designs, Sychev used a single sloped plate for the upper hull and the hull extension on which the main turret was placed. This would present a very well armored silhouette from the front. Only the frontal sections of the 2 turrets could be considered weak points. To decrease the effect of this, the front of the turret was rounded, while the entire turret resembled a horseshoe from the top, which made the weaker frontal plate as small as possible, similar to the later German Tiger I heavy tank.
While certainly ingenious, such use of thick armored plates would require intensive steel rolling and bending methods, which the Soviet industry lacked. This was a concern for almost all KV-4 designs, which featured various complex shapes. This issue would be fixed later in the war, with complex casting methods, though a new series of problems would be introduced, such as brittleness and porous steel.
The small commander’s cupola was not necessarily a weak spot in the overall tank’s armor, as it had around 100 mm of armor all around. When in use, only the head of the operator would be inside of it. The machine gun and turret were operated via mechanical controls that were lowered down to chest level.
Armament
Regarding the armament, the main gun used on all KV-4 designs was the 107 mm ZiS-6, developed earlier that year at Factory No.92 under the name F-42. Its designer was the famous Soviet gun designer, V.G.Grabin. It was to be mounted on the KV-3, KV-4, and KV-5 heavy tanks. During summer 1941, the gun was tested on a modified KV-2, with the KV-3 gun mantlet. It had a muzzle velocity of 800 to 880 m/s, shell weight of 18.8 kg, and could penetrate 115 mm of armor at 1,000 m.
The secondary armament on Sychev’s KV-4 consisted of a 45 mm 20-K gun, which was the main gun in service on Soviet tanks at the time. It was mounted in an independent turret, allowing it to engage infantry or lighter armored AFVs independently of the main turret. Moreover, two 7.62 mm DT machine guns were mounted, one coaxially with the 45 mm gun and one in the small cupola on top of the main turret.
KV-2 armed with a 107 mm ZiS-6 during firing trials, June 1941. The man in white uniform was V.G. Grabin himself.
Source: State Archives
Conclusion
Sychev’s KV-4 design had impressed Kotin and Zaltsman, was given 4th place in the competition, and he was awarded 2,000 Rubles. The tank featured 2 roomy turrets, well spaced from each other, offering great firing angles and fire coverage. The solutions regarding the engine cooling system and layout were inspired from the SMK and were deemed as effective. Lastly, the flat and steeply armored upper frontal plate ensured excellent protection, especially compared to the designs that opted for a “stepped” layout, like on the KV-1. Despite the large sums of money poured into the project, as well as almost an entire design bureau focusing on it, the KV-4s development stagnated after the competition results were announced. Instead, based on these results, the KV-5 began being developed. The final nail in the coffin for all the LKZ’s heavy tanks was the German invasion of the USSR, and, subsequently, their fast approach towards the city of Leningrad. Consequently, the entire SKB-2 design bureau was evacuated to the ChTZ factory in Chelyabinsk. Here, the wild dreams of heavy tanks were left behind and focus shifted on more down-to-earth solutions.
KV-4 as designed by Sychev. illustration by Pavel Alexe, funded through our Patreon campaign.
KV-4 Sychev specifications
Dimensions (L-W-H)
9.23 – 3.40 – 4 m
Total Weight, Battle Ready
95 – 100 tonnes
Crew
8 (commander, main gunner, main loader, turret mechanic/loader assistant, driver, radio operator, secondary gunner, secondary loader)
Propulsion
1,200 hp diesel V-12 M-40 with 4 TK-88 turbochargers
Speed
40 – 45 km/h (hypothetical)
Armament
107 mm ZiS-6 (F-42)
45 mm 20-K
2x DT 7.62 mm machine guns
Armor
Turret: 135-125 mm
Hull: 130 mm front, 125 mm sides and rear
Top and belly: 40 mm
KV-4 as designed by G. Kruchyonyh, which was the heaviest design of them all, at 107 tonnes.
Soviet Union (1941)
Super Heavy Tank – Blueprints Only
A few months prior to the German invasion of the USSR in 1941, the Soviets started a heavy tank program based on rumors of German heavy tank developments. One of the outcomes was the KV-4 competition, which involved 27 different tank proposals. The heaviest of them all, designed by G.V. Kruchyonyh, would have weighed 107 tonnes, but the design was not successful.
Development
–Dear reader: A more detailed development analysis of the KV-4 program can be found in the KV-4 Dukhov article–-
By 1941, the Soviet Union had experimented with several types of heavy tanks, from some very extravagant super heavy tanks, such as the Grotte proposals and T-42, to more “sensible” designs, such as the KV-1 and its later development, the KV-220. Yet, when the Soviet intelligence services sent a report about the development of German tanks in March 1941, the GABTU (Main Directorate of Armed Forces) was caught off-guard. The report mentioned, among others, the development of a 90-tonne heavy tank armed with a 105 mm gun.
At the time, the USSR’s main heavy tank force consisted of the hopelessly obsolete T-35 and the mechanically unreliable KV-1, which was pressed into service prematurely. Their most capable vehicle was the aforementioned KV-220, which weighed 67 tonnes, had 100 mm of armor and an 85 mm F-30 gun. While this was by no means an inadequate tank on paper, in practice, the testing of the vehicle was going slowly due to a wide variety of issues, such as the unreliability of the engine and various mechanical breakdowns. By the end of the program, only 2 prototypes were built.
Thus, the GABTU began the urgent development of a new heavy tank, and on 21 March 1941, they requested that a new 70-tonne tank be designed and developed to face this new German threat. It was to be armed with the new 107 mm ZiS-6 as well as a 45 mm gun and 3 machine guns. The engine was to be the M-40 1,200 hp V-12, with 4 TK-88 turbochargers. Armor was 130 mm at the front and 120 mm at the sides. The SKB-2 design bureau at the Kirov Leningrad Plant (LKZ) was tasked with its development and thus was named KV-4, with the GABTU index Object 224. This design bureau had plenty of experience in designing heavy tanks, having already designed tanks such as the SMK, KV-1, T-150, KV-220, and KV-3. As part of this, SKB-2 was ordered to have blueprints ready by 17 July 1942.
However, on 7 April, the requirements were once again changed. The KV-3 was to be revived, and its specifications vastly improved. In turn, the KV-4’s weight would be increased to 75 tonnes, and have its armor increased to 125 mm at the sides and rear. The deadline was also brought forward to 15 June. Most interestingly, LKZ was also assigned the development of the KV-5, a 90 tonne tank, with 150 to 170 mm of armor but also armed with the 107 mm ZiS-6. It would compete against the KV-4, with trials expected to be held in the beginning of 1942. In the meantime, until either entered mass production, the KV-3 would act as a stopgap.
The head of the project was J.Y. Kotin, who was also the head of the design bureaus at LKZ. However, instead of giving direct design orders, he took advantage of the loose requirements and set off to test his engineers. Thus, with the approval and budget from factory director I.M. Saltzman, he forged a competition for the KV-4’s development. The idea was that the engineers from the SKB-2 design bureau would compete against each other, with the top 7 places receiving financial rewards.
The results of the competition were announced on 9 May, with 13 designers receiving awards (7 total places, with some designs receiving the same spot). First place went to N.L. Dukhov’s design, which was considered the most sensible alternative, essentially just an enlarged KV-220. He received 5,000 rubles. Second place went to the Kuzmin, Tarotko, and Tarapantin, a trio of designers who worked together. They received 3,000 rubles to split. Their design had the main gun mounted in the hull, with a small turret over the fighting compartment. Third place went to N.V. Tseits, who designed a tank with a very low hull but massive cylindrical turret. He received 2,800 rubles. Fourth place was given to 2 designs. The first was by L.E. Sychev, who designed an enlarged SMK/style vehicle with a steeply angled frontal place, receiving 2000 rubles. Second 4th place was given to A.S. Yermolaev (also awarded 2000 rubles) who designed two standard layout tanks, with the only difference being the addition of a secondary turret on one of them. N.F. Shasmurin received 5th place with one of the more unique designs, mounting the main gun inside a casemate and a KV-1 turret on top. On 6th place, two more designers were awarded the same place. One of the was by K.I. Buganov, with a compact hull and rear mounted stacked turrets. The other was by N.G. Moskvin, which also proposed a standard layout tank with stacked turrets. Both designers were awarded 1000 rubles. Lastly, 6th place was given to 3 designs, with one by L.N. Pereverzev, which featured exposed tracks, similar to early Churchill tank designs. Another 6th place was awarded to Bykov, which was inspired from the SMK layout. Another designer, Kalivod, was also given 6th place but we do not yet know how his design looked like. The remaining designs did not receive any awards. Amongst them was that by G.V. Kruchyonyh, who designed the heaviest competitor, a 107 tonne tank.
As a peculiar side note, allegedly the blueprints of Kruchyonyh’s designed had been misslabeled by N.F. Shashmurin as the KV-5, to show the poor design of the KV-5. This claim was made by historian Yuri Pasholok.
G.V. Kruchyonyh
Georgy Vasilyevich Kruchyonyh was one of the oldest and most experienced tank designers at the SKB-2 design bureau in Leningrad, having worked on Soviet tanks since the 1920s at the Leningrad No.100 experimental tank building factory. During the 1930s, he worked on the T-28, SMK, and KV-1 at the renamed LKZ, and, after the factory’s transfer to ChTZ (later ChKZ), he would work on the KV-13, IS, and various tank vision devices. Yet, one of his most influential works was his marvelous design for the turret for the Kirovets-1, later IS-3. He retired from ChKZ in 1957, having received throughout his career the Stalin Prize, Order of the Great Patriotic War, and the Badge of Honor.
Georgy Vasilyevich Kruchyonyh with his awards. He was a photography enthusiast.
Source: Constructor of Combat Vehicles
Design
During the 1930s and 1940s, when multi-turreted tanks were a common theme, two main solutions were used when 2 turrets of different sizes were involved. One was to mount the turrets in a “battleship style” configuration, where the smaller turret would be mounted at the front, while the larger one was pushed behind it. This was by far the most common solution, and had the main advantage of a lower silhouette and presented a smaller frontal target. This would automatically require a much longer hull, as well as decreasing the firing arc of the frontal turret. To fix this, the secondary turret could be mounted on top of the main turret, allowing for a 360° firing angle for both turrets, independent of one another, at the cost of a much taller tank profile and larger main turret.
Side cutout view of Kruchyonyh’s KV-4 proposal. The complex turret layout can be seen.
Source: ASKM
Kruchyonyh went with the second option. He would have the secondary turret, which was a simple cylindrical shape on top of the main turret. He would take this concept to the extreme, giving the commander, seated in the secondary turret, his own fully rotating cupola, armed with a DT machine gun, effectively having 3 turrets stacked on top of each other. Another such armed cupola was also placed on the frontal engine deck, for the bow gunner, as opposed to a ball-mounted machine gun in the hull. Despite this, the total height of the tank was 3.78 m, which was still lower than other KV-4 designs, namely the designs by Pereverzev and Shashmurin.
A problem created by placing the secondary turret centrally over the main turret is main gun recoil. From the drawings, it is clear that the gunner of the secondary 45 mm gun would have to be very careful with the position of his right leg. If the seats were attached to the secondary turret and offered independent rotation from the main turret, he and the other crewmen operating the secondary turret would be in the direct path of the main gun recoil, essentially rendering only 1 of the guns operational at the time. The more sensible option is to have the seats fixed into the main turret, however this would mean that the crewmen had to individually rotate themselves to keep in-line with the secondary turret.
The front of the hull was made from a single, curved plate, 130 mm thick. This offered maximal protection without several interlocking plates. The engine was right between the driver and main fighting compartment, with firewalls on either side. The ammunition for the main gun was stowed horizontally in the hull. Behind it was the fuel tanks, engine cooling, and air intake systems.
Top view of the tank, with cutouts for the 3 turrets. Note the rounded rear section of the main turret.
Source: ASKM
Crew
Though the GABTU specifications would request a crew of around 6 men, Kruchyonyh would design a tank with a crew of 9, which was likely the reason for why his design was not awarded anything in the competition.
The exact crew positions are not specified, but analysis of the blueprints suggests the following crew setup: tank commander, main gunner, 2 main loaders, secondary gunner, secondary loader, radio operator, driver, and bow machine gunner.
The driver sat at the front of the hull, on the left side. The bow machine gunner operated the small machine gun cupola on the engine deck. Only his head would fit in it, so the cupola and machine gun were operated via mechanical controls lower down.
The gunner, who had to be seated further away from the normal position due to the limitations of the turret ring and the need to push the gun forwards for space for the extra turret, was placed in the main turret. As a result, the gunner’s controls, including sight, had to be moved and angled. One of the main loaders was seated to the left of the main gun, with the other loader was likely in the hull, lifting shells from within it.
The 45 mm gun’s gunner and loader were positioned on the left and right side of the secondary turret respectively. The commander was seated behind the secondary gunner, in an elevated position and used the rotating cupola for a towering overview of the battlefield.
Armor
At 107 tonnes, one would expect that the armor would exceed its peer KV-4 designs. But that was not the case. It had 130 mm at the frontal plates and 125 mm at the sides and rear, just like most other designs. The dimensions were not drastically larger than other designs, with several KV-4s being both taller and longer. This could be attributed to many designers underestimating the final mass of their tanks, while Kruchyonyh was more accurate or was too pessimistic. In contrast, the lightest design was the winning one by Dukhov, weighing 82.5 tonnes, resulting in a 24.5 tonne weight span between the designs.
Armament
As required by the GABTU, the tank was armed with the 107 mm ZiS-6 gun, designed by legendary gun designer V.G. Grabin at Factory No.92, under the name F-42. It was tested on a modified KV-2 in summer 1941 and meant for the KV-3, KV-4, and KV-5 tanks. Production began shortly after, but only when it became clear that LKZ and subsequently Izhora factory could not deliver the tanks in time, the guns were melted, as there was nothing to mount them to. This deeply saddened and angered Grabin, who found it appalling that such powerful and functional guns were being destroyed at a time when any weapon was needed to fight the Germans.
The secondary armament was a 45 mm model 1937 or 1938 anti-tank gun, the same which was mounted on most Soviet light tanks of the time. While certainly obsolete in tank warfare by mid-1941 standards, it would have proven useful against infantry and soft-skin vehicles and in decreasing the wear and ammunition use of the main gun.
The tank was also equipped with 4 DT machine guns (tank variant of the DP-27). One was in each of the small rotating cupolas. The other 2 were mounted coaxially to the left of the main gun and secondary gun, giving the crew great flexibility in engaging several types of threats at different angles simultaneously.
KV-2 testing 107 mm ZiS-6 gun, summer 1941.
Source: State Archives
Tower of Babel
Kruchyonyh’s KV-4 was not seen as advantageous or having any original features and thus not rewarded. Its main drawbacks were the very high weight compared to other designs and the huge crew count of 9, while the GABTU had specified just 6 men. His convoluted 3 turrets stacked on top of another was likely seen as complicated, not revolutionary. In these regards, his design can be compared more to the KV-5, which would enter the design phase in May 1941. Despite weighing over 100 tonnes, the KV-5 had 170 mm of frontal armor and 150 mm of side armor, essentially making Kruchyonyh’s design pointless.
KV-4 as designed by G. Kruchyonyh, which was the heaviest design of them all, at 107 tonnes. Illustration by Pavel Alexe.
KV-4 Kruchyonyh specifications
Dimensions (L-W-H)
9.13 – 4.03 – 3.78 m
Total Weight, Battle Ready
107 tonnes
Crew
9
Propulsion
1,200 hp diesel/kerosene V-12 M-40 with 4 turbochargers
Speed
30 km/h (hypothetical)/h
Armament
107 mm ZiS-6
45 mm 20-K
4x DT machine guns
Armor
Turret: 130 mm
Front hull: 130 mm
Side hull:125 mm
Top: 50 mm
Belly:40 mm
Soviet Union (1941)
Super Heavy Tank – Blueprints Only
The KV-4 program started in March of 1941 at LKZ (Leningrad Kirov Factory), after rumors of the development of German heavy tanks. Instead of undergoing a conventional design path, J. Y. Kotin, head of the project, suggested a competition between engineers and the best entries to receive rewards. Second place was originally given to a trio of engineers, but the entry was later disqualified as it lacked a turret.
As the designs never received individual designations, aside from the general KV-4 and 224 (Object 224), most KV-4 designs are differentiated by adding the designers’ name(s). In this case, Kuzmin, Tarotko, and Tarapatin (KTT). A common name to refer to this design is K.T.T.S., which adds the Russian word “самоходка” (samokhodka) meaning self-propelled gun. This is misleading, however, as this was a heavy tank, not a self-propelled gun.
Development
–Dear reader: A more detailed development analysis of the KV-4 program can be found in the KV-4 Dukhov article–
Soviet intelligence services sent a report to the Main Directorate of Armored Forces (GABTU) on 11 March 1941, concerning the development of German tanks. Most noteworthy, or perhaps alarming, was the development of a 90 tonne heavy tank, armed with a 105 mm gun. With hindsight, we can say that these were some early plans of the Pz.Kpfw.VII or Löwe.
Soviet military officials immediately realized their lack of preparation in this regard. The only genuine heavy tank in service during the spring of 1941 was the KV-1. While it was good on paper, it had been rushed into service for propaganda purposes, more than as a direct combat weapon. Just a few months later, these critical shortcomings would come to haunt not just its LKZ designers, but the Soviet Army altogether, showing how unreliable, slow, and heavy the tank was. The KV-1, even on its best day, would not be enough in an all-out war. Thus, as early as 1940, work on heavier tanks commenced at LKZ, in the form of the T-150, the T-220, and later the KV-3. These were fine vehicles on paper, with guns and armor far superior to even the much later Tiger I, but they were very unreliable, i.e. the KV-220 broke 2 engines during its trials and weighed 62.7 tonnes.
A T-150 towing the KV-220 during trials.
Source: ofis-7andotherthings
Just 10 days after the initial report, on 21 March 1941, the GABTU sent the requirements for the development of the KV-4, designated Object 224 to LKZ, tasked with designing the vehicle, where it would be simply called “224”. The military required it to be a 70 to 72 tonne heavy tank, armed with the 107 mm ZiS-6 in the turret, as well as a secondary 45 mm 20-K and at least 3 DT machine guns. Armor was to be of 130 mm at the front and 120 mm towards the sides and rear. Propulsion was provided by a 1,200 hp M-40 engine, also developed at LKZ. Crew was to be of 6 men. The deadline for the blueprints was 17 July, after which they were to be sent to various factories responsible for component production, namely Plant No.92 for construction of armaments in September and to Izhora plant in October, in charge of hull and turret production.
At LKZ, specifically the SKB-2 design bureau, work had not even started when the GABTU changed their minds and altered the KV-4 requirements on 7 April, as well as those of the KV-3, which was now to be improved and act as a stopgap until the heavier KVs were made. Most surprisingly was the introduction of a new tank, even larger and heavier than the KV-4, the KV-5, with a mass of at least 90 tonnes and 170 mm of frontal armor. The KV-4 itself was also improved, its weight increased to 75 tonnes, frontal armor to 135 mm and side/rear to 125 mm.
Work on the KV-4 began on 10 April, with J. Y. Kotint as the head of the project. Due to the very loose requirements and ability to start from scratch, he decided to test his engineer’s creativity. Thus, with the approval of the factory director I.M. Zaltsman, he set up a competition for the KV-4’s designs. Engineers would brainstorm what the KV-4 would look like, encouraging original and innovative features.The top few designs would get a financial reward. Over 20 engineers competed, submitting over 20 individual designs. The winning design was that of N. L. Dukhov, which was essentially an enlarged KV-220, but with a peculiar semi-automatic loading system. Second place went to the trio of K. I. Kuzmin, V. I Tarotko, and P. S. Tarapatin, who designed a very unorthodox tank, resembling nothing seen before, with the gun mounted in a central rotating sponson, with a smaller turret on top, in a more ‘symmetric’ fashion compared to the American M3 Lee tank. Third place went to N.V. Tseits, with a more conventional design, but which sought to have as low a hull as possible, with a large cylindrical turret. Several other designers also received monetary compensation for their designs.
The Designers
This design was created by 3 different engineers working together, K. I. Kuzmin, V. I. Tarotko, and P. S. Tarapatin.
K.I. Kuzmin began his work at the Krasny Putilovets tractor plant, and would begin work at SKB-2 on the T-28. He would go on to work on most of SKB-2s tank projects, including the T-29, SMK, KV-1 also worked alongside L.E. Sychev on the PPG (Object 217). Furthermore, he worked on the KV-3, KV-4 and was design group leader on the KV-5 and was the hull designer of the KV-13.
V.I. Tarotko’s first project at SKB-2 was on the SMK, and later worked the KV-1 as part of a trainee team of young design engineers. After the start of the war, he began work on SPGs, including the SU-122 and SU-152. In late 1944, alongside G.N. Moskvin, V.I. Tarotko would develop the “pike-nose” armor layout for the Object 252U and IS-2U, becoming an iconic design feature on Soviet post-war heavy tanks. Afterwards he would work on the development of the IS-3 and IS-4. Worthy to note is that some documents mention S.V. Mickiewicz instead of V.I. Tarotko, though likely a mistake.
V.I. Tarotko
Source: Constructors of combat vehicles
Similarly to Tarotko, P.S. Tarapatin was also a young engineers, having just finished his studies. His career began working on developing the KV-1, but after the start of the war, he would work alongside his colleague Tarotko on the SU-122 and SU-152.
Design
The general layout of the KV-4 as proposed by the K.T.T. trio is one of the most unorthodox and unique amongst all other proposals. The driver and bow machine gunner sat in the hull, as on most other KV tanks. Yet right behind them was the engine and gearbox compartment, without any firewall or separation. Behind the powerpack was the fighting compartment, separated by a firewall. The main 107 mm ZiS-6 gun was mounted in a large, rotating sponson which could traverse 60° to both the left and right. Behind it, on the roof of the fighting compartment was a fully rotating turret, armed with a 45 mm 20-K gun. Right behind the fighting compartiment, separated by a partially curved firewall, was the air cooling system, which would both evacuate and intake air for the engine. While not ideal, there was simply no room to locate it closer to the engine. Thanks to the well integrated gun and low roof, the vehicle could have been relatively easy to transport (setting aside its weight) and presented a low profile, was it not for the small turret which placed it amongst the taller KV-4 designs, at 3.78 m. The engine was a M-40 V-12 aircraft engine, equipped with 4x TK-88 turbochargers, despite being a diesel engine. It had an output of 1,200 hp, and was connected to the gearbox which ran through the hull, in between the driver and bow machine gunner. Thus, the tank had frontal drive sprockets. It was estimated to reach a top speed of 36 km/h.
Due to its “turretless” layout, the tank is sometimes mistaken for a self-propelled gun, most notably, by Wargaming’s videogame World of Tanks. This is simply not the case. Similarly, N.F. Shashmurin had also opted to mount the main gun of his tank inside the hull, and after being forced (otherwise it would have been disqualified), he added a KV-1 turret on top. Truth is that there were plans on 18 April to design a KV-4 based SPG, but with just 60 mm of casemate armor and an improved 107 mm gun. The design by the K.T.T. trio is simply a heavy tank with the main gun mounted in the hull, albeit with a significant gun arc.
Side profile of the trio’s KV-4 proposal. The engine is situated between the driver and the fighting compartiment.
Source: ASKM
Crew
The crew was to be of 6 men, commander, gunner, 2 loaders, bow machine gunner, and driver. The gunner and one of the loaders sat within the fighting compartiment in the hull and manned the 107 mm ZiS-6 gun. The main gun shells were stowed on the floor of the tank and in racks to the rear of the compartiment. The tank’s commander and a second loader were in the turret. Here, the commander could scan the battlefield with the rotating turret, offering an excellent view, while also being able to independently engage targets. The second loader was also in the turret, but had to bend down from his seat to lift the light, 1.43 kg, 45 mm shells into the breech. Down into the hull, at the front, was the driver (left) and bow machine gunner (right), likely also tasked with operating the radio. Both had ball-mounted DS-39 7.62 mm machine guns at their disposal, for suppressive fire more than anything. Though lack of any other machine guns, especially one with an extended firing arc, in a “mostly” turretless vehicle is a major downside, especially as many other KV-4 designs had several turrets capable of rotating independently of each other.
Top down view of the KV-4 proposal where the 2 7.62 mm DS-39 bow machine guns can be seen.
Source: ASKM
Armor
Compared to other KV-4 designs, the tank in question’s armor was on the thinner side, with “just” 125 mm thick plates at the front, sides and rear. Top and belly plates were 40 mm thick. Curiously, despite being very similar to the T-50 or T-50-2 turret, the top turret was just as well armored, with what appears to be 125 mm thick plates all around, aside for the area around the gun mantlet and roof, which were 40 mm thick.
Armament
The main gun was the 107 mm ZiS-6, designed by V. G. Grabin in 45 days, at the request of Stalin himself for the new heavy tanks, although experiments and testing of similar guns started long before, in 1940. The shells weighed 18.8 kg and had a muzzle velocity of 800 to 840 m/s. Some sources claim it could penetrate 115 m of armor from 1,000 m.
The gun was mounted in a semi-rotating sponson. In other words, it was fixed on a rotating armored housing, where it could traverse 60° in both directions. Additionally, the gun had vertical movement of -5°. However, the elevation is unknown, as the document is damaged where the value is written. The crew would be required to move along with the gun, unless the gunner was attached to it, like in a conventional turret.
Regarding secondary armament, the tank had a single 45 mm 20-K Mod. 1938 gun, mounted in a smaller turret. It had 360° horizontal traverse and vertical elevation of +20°/-5°. This gun fired 1.43 kg shells with a velocity of 760 m/s. While this gun might seem underwhelming, in tandem with the 107 mm ZiS-6, it was more than useful. It was still the main gun in use on several Soviet tanks in service, from the BT-5, BT-7 and T-26, to the new T-50 and massive T-35. With hindsight, it is clear that this gun would quickly become obsolete, especially as a main weapon.
The KV-2 with the ZiS-6 107 mm gun and KV-3 mantlet during testing, June 1941.
Source: Thinky via WT forums
The tank only featured 2 DS-39 7.62 mm machine guns, both in fixed ball mounts in the hull, for the driver and bow gunner/radio operator. This opened large fire blindspots for the semi-turretless tank, increasing the dependence on the 45 mm gun, and in turn, strain on the commander, who acted as its gunner. Even so, the lack of any other machine gun meant that suppressive fire was impossible and the tank was vulnerable to rear infantry attacks.
Misinterpretation
The 3 engineers sought to create an eccentric vehicle, with several unique features, such as the sponson-mounted main gun or engine cooling layout. For these, Kotin and the judges initially awarded the design second place, landing the 3 men 3000 Rubles to share. However their joy was short-lived, as their design was later disqualified after concerns that it did not fit the GABTU’s requirements, which originally specified that the main gun was to be mounted in a fully-rotating turret. This detail was (likely) omitted in the second request. The result of their disqualification meant that the design by N.V. Tseits would be lifted to second place, which had a direct impact on the development of the KV-5, which used many aspects of Tseits’ KV-4 proposal. Oddly, Shashmurin’s design, which also mounted the main gun in a casemate, was not disqualified. Furthermore, he used the “wrong” gun, placing a KV-1 turret and gun on the roof of the casemate.
The KV-4 proposal as it is represented in the game World of Tanks, called KTTS. Note that it does not have the original 107 mm ZiS-6, but rather it has the 107 mm M-75, a gun which the KV-4 heavy tank was never intended to equip.
Source: Wargaming
The entire KV-4 project was rather hopeless. After the announcement in May of the competition’s winner, N.L. Dukhov, work on the KV-4 virtually stopped. Instead, the team shifted focus towards preparing blueprints for the KV-5. Work on these heavy tanks was slowed down by the German invasion of the USSR on 22 June, and eventually, completely halted in September, when German troops were approaching Leningrad and the SKB-2’s design bureau was evacuated to ChTZ, later renamed ChKZ, in Chelyabinsk.
The KV-4 as designed by Kuzmin, Tarotko, and Tarapatin (KTT). Illustration by Pavel Alexe.
KV-4 K.T.T. specifications
Dimensions (L-W-H)
9.26 – 3.175 – 3.78 m
Total Weight, Battle Ready
88 tonnes
Crew
6 (Commander, Gunner, Driver, Radio operator, loader, turret mechanic/loader assistant)
Propulsion
1,200 hp diesel/kerosene V-12 M-40 with 4 turbochargers
Speed
36 km/h (hypothetical)
Suspension
Torsion bar, 7 wheels per side
Armament
107 mm ZiS-6 (F-42)
45 mm 20-K
2x 7.62 mm DS-39 machine guns
Armor
Front: 125 mm
Side: 125 mm
Rear: 125 mm
Top and belly: 40 mm
Interpretation of Kreslavsky's KV-4 design by Pavel Alexe. Illustration funded through our Patreon campaign.
Soviet Union (1941)
Super Heavy Tank – Blueprints Only
The KV-4 program can be regarded as one of the most unsuccessful and short-lived tank design ideas of the Soviet Union during the WW2 period. This is especially true considering its expectations, the caliber of the engineers behind it, J. Y. Kotin and N. L. Dukhov, to name a few, and those who ordered it to begin with, including Stalin himself. Many designs were proposed in what was essentially a drawing competition, some quite sensible, while some were less so. One rather forgettable design was that by young engineer M. I. Kresavsky, who did not receive any awards for his design. Big, heavy, and with no advantages over other designs, it remained, and still is largely, forgotten, with just minor recognition in Wargaming’s World of Tanks.
Development
–Dear reader: A more detailed development analysis of the KV-4 program can be found in the KV-4 Dukhov article–
Despite the Molotov-Ribbentrop Pact, and previous German-Soviet tank collaborations, in 1941, the situation in Europe was ugly, and German expansion was worrying for the Soviets. Things took a turn for the worse when, on 11 March, a report submitted by the Soviet Intelligence agencies regarding German armament development included a chapter on German heavy tanks. Here, amongst other tanks, a 90-tonne heavy tank armed with a 105 mm gun was mentioned. The Soviet military, recognising its unpreparedness against such a threat, ordered work on a Soviet tank that could match such an enemy tank.
Just 10 days after the initial report was sent, on 21 March, the GABTU (Main Directorate of Armed Forces) sent out the request for a new heavy tank, designated Object 224 or KV-4, as it was to be designed at the Leningrad Kirov plant (LKZ). The design of the tank was to be done by the SKB-2 design bureau, headed by the famous tank designer J. Y. Kotin. The Soviet state requested the tank to be a 70-72 tonne tank and armed with the 107 mm ZiS-6 main gun, a secondary 20-K 45 mm gun, 3 machine guns, and 1 flamethrower. Armor was to be of 130 mm at the front and 120 mm towards the sides and rear. Propulsion was to be provided by an M-40 aviation diesel engine, with 4 TK-88 turbochargers, outputting 1,200 hp. The crew was to be of 6. Deadline for the tank plans was 17 July.
It was not long until the GABTU changed their minds and, on 7 April, reordered the entire program. Firstly, the KV-3, which was previously under development, was reinstated and upgraded to act as a stopgap tank until the KV-4 and KV-5 were ready for production. The KV-5 itself was created, a 90-tonne tank which would have had 170 mm of armor at the front and 150 mm at the sides, though same armament and powerpack as the KV-4. The 2 would compete against each other, and the winning vehicle would be produced. The specifications of the KV-4 were also tampered with, increasing the weight to at least 75 tonnes, 135 mm of frontal armor and 125 mm on the sides and rear. The deadline for the tank’s drawings was narrowed to 15 June.
Work began on 10 April at LKZ, and Kotin, after seeking approval and funding from factory director I. M. Zaltsman, decided to let the engineers compete against each other. The best designs would be financially rewarded. The SKB-2 design bureau already had experience with heavy tank development. It was the same group of people behind the SMK, T-100, KV-1, T-150, KV-220, and KV-3. Over 20 engineers from SKB-2 competed against each other, some even teaming up, presenting well over 20 different tank designs. The winner was N. L. Dukhov, with a KV-4 that was essentially just an enlarged KV-220. Second place went to the trio of K. I. Kuzmin, V. I Tarotko and P. S. Tarapatin, which had the main gun inside the turret (and later got disqualified), and third place to N. V. Tseits, whose design featured a very low profile hull, but a massive turret. Though not all designs were as well received. Over 10 designs did not receive any rewards. One of these was the one by engineer M. I. Kresavsky.
M.I. Kresavsky
A young engineer from the Leningrad Politechnic institute, M.I. Kresavsky (also sometimes spelled Kreslavsky) was drafted by Kotin and worked for him for 30 years. Apart from his work on the KV-4, Kreslavsky worked on the SMK and the transmission of the KV-1, alongside V. A. Kozlovsky. He also participated in the design of the KV-2 and IS tanks. A young M.I. Kresavsky at SKB-2.
Source: Constructor of Combat vehicles- N.Popov
Design
At first glance, the KV-4, as designed by Kreslavsky, was nothing special, other than its sheer size. At exactly 9 m in length, and over 4 m in width, it landed on the larger side of the KV-4 spectrum. Mass-wise, the 92.6 tonne design was around average, with the lightest design being 82.5 tonnes and the heaviest 107.7 tonnes. Yet, a couple of details make it into a rather strange design from a mechanical aspect. Primarily, the engine was mounted over the 3rd and 4th roadwheels, right behind the driver, separated by a firewall. The transmission protruded through the firewall towards the final drive, located at the driver’s feet. This, in turn, worked the front drive sprockets. In terms of propulsion, the tank was, as requested by the GABTU, equipped with an 1,200 hp M-40 engine, with 4 TK-88 turbochargers. For vision, the driver had a complex, rounded armored bulge, extending from the hull, made from several cast and welded components. The bow machine gunner had his own such “bulge” on the opposite side of the hull.
The turret and fighting compartment were behind the engine room, separated by another firewall. Inside the hull, ammunition was stowed. Above was the hexagonal turret, made from 125 to 130 mm plates pressed into shape and welded together. On top, a conical turret with several vision slits was attached. The main 107 mm ZiS-6 gun was mounted to the left of the center, while the 45 mm 20-K to the right. Back inside the hull, a 4th compartment was added, which housed the fuel tanks and engine cooling system, which was pulled through the fighting compartment. While seemingly complex, this entire layout offered several advantages. Firstly, it protected the crew, ammunition, and fuel tanks from frontal impacts. Secondly, the turret was offset far enough to the rear that the gun barely hung over the hull, easing transport and reducing potential barrel damage during maneuvers in areas such as cities or forests.
Cutout side view of Kreslavsky’s design. Source: ASKM
Crew
The vehicle had a crew of 6: commander, gunner, 2 loaders, driver, and bow machine gunner/radio operator. The commander, seated in the back of the turret, operated the cupola, equipped with 6 vision slits and one 7.62 mm DT machine gun. The gunner sat to the right of the 107 mm main gun and was very likely able to remotely operate the 45 mm gun too. The 2 guns had individual loaders sat behind them. Another ball-mounted DT machine gun was mounted on the rear plate of the turret, likely to be used by one of the loaders. There are no visible entry/exit hatches, but a reasonable assumption would conclude that there would be 2 hatches, one on the cupola and another on the left side of the turret roof.
The driver and bow gunner were seated in the hull, each on either side of the gearbox. Both had their own armored, rounded protrusions, which allowed for more headroom and better visibility, equipped with at least 4 vision slits each.
Top view drawing of Kreslavsky’s KV-4. The tracks are missing from this scheme. Note the gun mantlet and the way the guns are placed. Source: AKSM
Armor
In relation to other KV-4 designs, the armor on Kreslavsky’s KV-4 was nothing special. Frontal plates on both the hull and turret were 130 mm thick and rounded, increasing the effectiveness from certain angles. Only the frontal upper plate was thinner, at just 80 mm, though it was angled at 10° from horizontal, bringing it to an LoS thickness of 461 mm. Armor on the driver’s cupola varied from 125 mm at the front to 60 mm on the roof. Side and rear armor was 125 mm thick, while roof armor was 50 mm and belly armor was 40 mm thick.
Armament
The main gun on all KV-4 designs was the ZiS-6, with a 107 mm caliber, designed by the famous V. A. Grabin. By March 1941, the Soviets had already worked for several months on 107 mm caliber guns, and were proving to be very powerful, especially in regards to armor penetration. Thus, when the news of German heavy tanks came, Stalin himself rang Grabin, requesting the design of a new, powerful gun. Thus the F-42 was born, completed in just 45 days. In March, it was renamed to ZiS-6. Factory trials proved promising after delayed tests were conducted on a KV-2 armed with the gun and a KV-3 gun mantlet. Production started shortly after. However, according to Grabin’s memoirs, after the cancellation of the LKZ heavy tanks, over 800 such gun barrels had to be melted. The gun itself had an 18.8 kg one-piece shell, with a muzzle velocity between 800 to 840 m/s.
One of the first ZiS-6 107 mm guns produced. Source: Yuri Pasholok via Warspot
The secondary armament, a 20-K 45 mm, was mounted coaxially, to the right of the center of the mantlet. There was no space in between the 2 guns for another gunner, so it is assumed that the main and single gunner sat to the left of the main gun, and could remotely operate the 45 mm gun too, using some form of mechanical system. The gun itself fired BR-240SP AP rounds, which weighed 1.43 kg, had a muzzle velocity of 757 m/s and a (artificially calculated) penetration of 73 mm at 0 m.
A total of 3 DT 7.62 mm machine guns were mounted on ball mounts in the tank, one by the bow machine gunner, in the hull, one in the commander’s cupola and one on the rear turret plate, likely operated by one of the loaders, when necessary.
Drawings og the 45 mm K-20 gun with its turret gun mount. Source: Armored Wiki via VK.com
Dinosaur Extinction
The KV-4 program did not go far at all. The LKZ staff failed to present final blueprints in time, and the program was delayed. Without them, the Izhora plant, tasked with production of the tank prototype, could not begin work either. The truth is that the program slowly died after the competition, and work shifted towards the more exciting KV-5. With the German invasion of the Soviet Union on 22 June 1941, work still continued. Only in August, when the German forces were approaching Leningrad, did work on these tanks pause. The SKB-2 design bureau was evacuated to the ChTZ, later renamed ChKZ in Chelyabinsk, and work on the KV-4 never resumed.
Conclusion
Though one might see the KV-4 program as unlucky and doomed, Kresavsky’s own proposal was even more so. It failed to spark any interest from the ‘judges’ and brought nothing revolutionary enough, in what was actually quite a large tank, even compared to other KV-4 designs. Only in the recent decade has Kreslavsky’s proposal received some ‘love’, being introduced in the massively multiplayer online game, World of Tanks.
KV-4 Kresavsky as interpreted by Wargaming. Note that it does not have the original 107 mm ZiS-6, but rather it has the 107 mm M-75, a gun that the KV-4 heavy tank was never intended to mount. Source: TheDailyBounce.netInterpretation of Kresavsky’s KV-4 design by Pavel Alexe. Illustration funded through our Patreon campaign.
KV-4 Kresavsky Specifications
Dimensions (L-W-H)
9.0 – 4.0 – 3.225 m
Total weight, battle-ready
92.6 tonnes
Crew
6 (commander, main gunner, driver, secondary gunner, radio operator, & loader )
Propulsion
1,200 hp diesel V-12 M-40 with 4 turbochargers
Speed
45 km/h
Suspension
Torsion bar, 7 wheels per side
Armament
107 mm ZiS-6 (F-42) (103 rounds)
45 mm Mod.1937 20-K coaxial (140 rounds)
3x 7.62 mm DT machine guns (4,000 rounds)
Armor
Turret: 130 mm
Front hull plate: 130 mm
Front upper plate: 80 mm
Side plate: 125 mm
Rear plate: 130 mm
Top: 50 mm
Bottom: 40 mm
Interpretation of Tseits' KV-4 design by Pavel Alexe. Illustration funded through our Patreon campaign.
Soviet Union (1941)
Super Heavy Tank – Blueprints Only
The KV-4 heavy tank program was started in April of 1941, based on an illusion of Soviet Intelligence services, which claimed that the Germans were working on a 90-tonne heavy tank. Design was undertaken at the LKZ factory via a competition of engineers. Amongst them was senior engineer N. V. Tseits, who designed one of the most successful KV-4 designs, being awarded third, and later, second place.
Development
–Dear reader: A more detailed development analysis of the KV-4 program can be found in the KV-4 Dukhov article–
On 11 March 1941, the Soviet intelligence services sent a report to the Main Directorate of Armed Forces (GABTU) regarding German tank development. Amongst several other topics, heavy tanks had been discussed, of which a 90 tonne heavy tank armed with a 105 mm gun which was apparently under development.
This came as a large surprise to the Soviet military officials, which immediately realized their lack of preparation in this regard. At the time, the KV-1 was the main heavy tank of the Soviet armored forces, but it was completely unprepared for service, let alone combat. Its problems would become apparent at the start of the German invasion of the USSR, highlighting its poor mobility and mechanical unreliability. Work began as early as 1940 on creating a heavier and better armored KV-1, most notably the T-150, KV-220, and later the KV-3. Here, it is relevant to remember that even the KV-220, armored with a 85 mm gun, could have stood up to even the Tiger I, which entered service over a year later, had its crucial mechanical problems been fixed.
Shortly after, on 21 March 1941, the GABTU sent out the requirements for the development of the KV-4, designated Object 224, or just 224. It was to be a 70 to 72 tonne heavy tank, armed with the 107 mm ZiS-6 in the turret, as well as a secondary 45 mm 20-K and at least 3 DT machine guns. Armor was to be of 130 mm at the front and 120 mm towards the sides and rear. Propulsion was provided by a 1,200 hp M-40 engine, also developed at LKZ. Crew was to be of 6 men. On 27 March 1941, the deadline for the tank design was set to 17 July, not including the prototype building and armament testing, which were set as late as October of the same year.
Yet, in an unanticipated turn of events, on 7 April 1941, the GABTU rethought the requests on the KV-4. The weight was raised to 75 tonnes, and armor as thick as 135 mm. Side and rear armor was to be 125 mm thick. The blueprints’ deadline was also narrowed, to 15 June. It was at this time that the KV-5 was requested, a tank that was to weigh at least 90-tonnes, have 170 mm of armor at the front and 150 mm at the sides. Additionally, the KV-3 was ‘revived’ and improved to fulfill a stopgap role until the KV-4 and KV-5 tanks were ready for production.
At LKZ, the SKB-2 design bureau began work on 10 April. Head of the project was the famous J. Y. Kotin, who, after seeking approval and funding from factory director I. M. Zaltsman, decided approach the design of the tank in an unusual way, by creating a competition between the SKB-2 engineers. The top few designs would get a financial rewards. Over 20 engineers competed, submitting over 20 individual designs. The winning design was that of N. L. Dukhov, which was essentially an enlarged KV-220. Second place went to the K. I. Kuzmin, V. I Tarotko and P. S. Tarapatin trio, who submitted a tank with the main gun in the hull and secondary gun in a small turret. Third place went to N. V. Tseits, who submitted a tank with a very low hull, but large turret, to offset the lack of hull space.
N.V. Tseits
Nikolai Valentinovich Tseits* was born in Moscow in 1884 and studied engineering at the Bauman Moscow State Technical University, graduating in 1922. In 1925, he started working at the Ordnance-Arsenal Trust and from 1928 onwards worked in the Kazan German-Soviet tank facility. In 1930, he was arrested on counter-revolutionary charges and sentenced to 10 years in labor camps, but the charges were dropped in 1932, after working at a automobile and tractor design bureau. From 1934, he worked at the experimental plant No.185 and, from 1937, at the SKB-2 design bureau of LKZ, where he was the oldest, most knowledgeable and, in turn, most respected engineer. Through his tank design career, he worked on the T-28, T-29, T-35, SMK, KV-3, KV-5, and, lastly, the KV-13. In 1942, after working non-stop for months on the KV-13, he was granted 1 week leave by head engineer J. Y. Kotin, which he used for hunting. Upon his return to ChKZ in Chelyabinsk, he felt unwell and died shortly after at the factory medical office from an unidentified cause. According to the memoirs of N. F. Shashmurin, who was in the room before his death, Tseits had gifted him a slide ruler to remember him by. Tseits was 68 years old at the time. He was awarded the Order of Lenin and Order of the Badge of Honor.
*the spelling Tseits is an anglicized version of the Cyrillic name Цейц.
Nikolai Valentinovich Tseits. Source: Wikimedia commons
Design
In terms of general layout, Tseits kept his design traditional, with the engine towards the rear and turret in the center of the hull. What was not traditional, at least for a Soviet tank, was the final drive, which had been moved to the front, as opposed to having it combined with the engine. Another unusual feature was the very low hull roof. In order to offset the low hull, the turret was large in all directions, so much so that it had to be ‘lowered’ into the hull, with the turret ring being below the level of the driver’s head. The height of the turret allowed for the main gun ammunition to be stowed vertically, in great numbers, with 100 to 120 rounds stowed on the turret side walls and underneath the turret ring. A secondary turret was placed on top, armed with a DT 7.62 machine gun.
The 1,200 hp M-40 engine, with 4 TK-88 turbochargers, was housed at the rear of the hull, resembling modern MBTs, as opposed to a design from 1941. The air cooling was directed via a protruding chamber, at the rear, as opposed to a curved plate, as on most KV tanks. The driveshaft ran from the engine over the torsion bars and underneath the fuel tanks that were in the center of the hull, underneath the turret ring. The final drive, brakes and gearbox were placed at the tip of the hull, at the feet of the driver and bow machine gunner.
Side view of Tseits’ KV-4 design. Note just how short the hull is in comparison to the turret height. Source: ASKMTop view of Tseit’s design. The circular turret can be seen, as well as part of the ammunition layout. Source: ASKM
Crew
As designed, the tank was to have a crew of 7 men: commander, main gunner, main loader, loader assistant, driver, bow machine gunner and radio operator/secondary turret operator.
Unfortunately, exact positions for all the crewmen are not given, so some speculation is required. The driver and bow machine gunner were both seated inside the hull. Here, the hull roof was lifted to allow for placement of the 7.62 mm bow machine gun in a ball mount and to give room for the 2 crewmen’s heads. The driver had 3 periscopes for vision, in addition to the vision slit in the hull. The rest of the crewmembers were likely placed in the roomy turret. The gunner was to the left of the gun and the commander to the opposite side, on the right. Behind them were the 2 main loaders, each tasked with loading the gun from the opposing sides of the turret walls. The ammunition stowage did not have any rotation system, similar to later autoloaders, thus requiring several loaders to reach all sides.
Armor
The turret was made from curved armor plates into a semicircle 125 mm thick. The only exception was the front of the turret, which consisted of a single, angled, flat plate, 130 mm thick. On it was the gun mantlet. The roof of the turret was partly angled at the front and 50 mm thick. The lower frontal plate was 130 mm, as was the front of the driver’s cubicle. The upper frontal plate, angled very steeply, sas just 50 mm thick. Hull sides and rear were 125 mm thick. Other areas were 50 to 40 mm thick.
Armament
The main armament was the ZiS-6 107 mm gun, previously named F-42. It was designed by the famous V. G. Grabin in record time at Stalin’s personal request for the new heavy tanks. The gun was tested, after many delays, in June 1941 on a KV-2 with a KV-3 mantlet, and after good performances, entered production. According to Grabin’s memoirs, around 800 barrels had been built, and subsequently melted down after the failure of the KV-3, KV-4. and KV-5 programs. The gun could fire an 18.8 kg one-piece shell at 800 to 840 m/s.
KV-5
Tseits’ design was greatly appreciated and placed 3rd in the competition, losing only to Dukhov’s design and the design by the K. I. Kuzmin, V. I. Tarotko, and P. S. Tarapatin trio. However, shortly after, the latter design, which placed second, was ‘disqualified’, likely due to the design not respecting original technical specifications and requirements. This, in turn, moved Tseits’ design up to second place.
On 7 April, in addition to changing the specifications of the KV-3 and KV-4, the GABTU requested an entirely new tank, larger and heavier than the already 80 to 90 tonne KV-4. It was to weigh at least 90 tonnes, have armor as thick as 170 mm at the front and 150 mm at the sides. J. Y. Kotin initially intended to start its development in the same way as on the KV-4, via a competition between engineers. But, as the requirements were similar (and equally vague) to the KV-4, it was decided to save time and use the results from the KV-4 competition. As a result, Tseits’ design, now being on second place, was chosen as the basis for the KV-5, and N.V. Tseits was chosen as senior machine designer of the project. Other engineers that placed high in the competition were given different roles in designing different segments, such as K.I. Kuzmin (head of design group), L. E. Sychev, A. S. Ermolayev, L. N. Pereverzev, and V. Bykov among others.
The design was kept very similar to Tseits’ KV-4 design, such as the large turret and low hull, but major changes were made, including moving the final drive to the rear, making the turret a pentagonal shape (much easier to weld straight plates compared to stamping them into a curve), as well as the driver and bow machine gunner being seated into individual ‘pods’.
Original blueprints of the KV-5 showing the hull. Source: ASKM
Conclusion
The KV-4 design created by N.V. Tseits was, arguably, the most successful KV-4 design. While N.L. Dukhov’s design did win the competition and was to become the final variant of the KV-4, Tseits’ design was the basis of an even more powerful tank, in the form of the KV-5. However, considering the KV-5s nearly pointless birth, short life and unmourned death, it is not much of a gratification to a series of projects considered by the designers themselves as madness.
Interpretation of Tseits’ KV-4 design by Pavel Alexe. Illustration funded through our Patreon campaign.
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Soviet Union (1941)
