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WW2 Soviet KV-4

KV-4 (Object 224) Sychev

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

KV-4 designs
Placement Name Drawings Mass (t) Dimensions (m) (LxWxH) Armament Crew Top speed (theoretical) Armor Reward /Rubles
1 Dukhov KV-4 82.5 8.150
3.790
3.153
107 mm ZiS-6
45 mm K-20
2x 7.62 mm DT machine guns
6 40 km/h Front top plate: 135 mm
Front bottom plate: 130 mm
Side plate: 125 mm
Top and belly: 40 mm
5000
2 Kuzmin, Tarotko, Tarapatin KV-4 88 9.26
3.78
3.175
107 mm ZiS-6
45 mm K-20
2x 7.62 mm DS-39 machine guns
6 36 km/h Front: 125 mm
Side: 125-100 mm
Top and belly: 40 mm
3000
3 Tseits KV-4 90 8.85
4.03
3.62
107 mm ZiS-6
2x 7.62 mm DS-39 machine guns
Unspecified flamethrower
7 45 km/h Front hul upper plate: 50 mm
Front hull bottom plate: 125 mm
Turret:130 mm
Side plate: 125 mm
Top and belly: 50 mm
2800
4 Sychev KV-4 95 – 100 9.23
4.00
3.40
107 mm ZiS-6 (F-42)
45 mm 20-K
2x 7.62 mm DT machine guns
6 40 – 45 Turret: 135-125 mm
Hull: 105 mm
Top and belly: 40 mm
2000
4 Ermolaev KV-4 90 8.22
4.00
3.25
107 mm ZiS-6 6 35 130 mm
95 8.52
4.00
3.25
107 mm ZiS-6
45 mm 20-K
6 35 130 mm 2000
5 Shashmurin KV-4 92 9.50
4.00
3.85
107 mm ZiS-6 (F-42) main cannon (112 or 102 rounds)
76 mm F-11 secondary cannon (120 rounds)
2x 7.62 mm DT machine guns (400 rounds)
Unspecified flamethrower (hull)
7 35 km/h Front top plate: 125 mm
Side plate: 125 mm
Top and belly: 50 to 40 mm
1500
6 Buganov KV-4 93 7.70
3.80
3.90
107 mm ZiS-6
45 mm 20-K
6 50 km/h Front 125 mm 1000
6 Moskvin KV-4 101 9.573
4.03
3.74
107 mm ZiS-6
45 mm 20-K
6 40 km/h Front 130 mm 1000
7 Pereverzev KV-4 100 9.5
3.8
3.82
107 mm ZiS-6
45 mm 20-K
2x 7.62 mm DT machine guns
6 39 km/h Front: 125 mm 500
7 Bykov KV-4 98.6 9.5
4.03
3.65
107 mm ZiS-6
45 mm 20-K
7.62 mm DS-39 machine gun
8 36 km/h Front 130 mm 500
7 Kalivod KV-4 500
N/A Fedorenko KV-4 98.65 8.10
4.03
3.70
107 mm ZiS-6
45 mm M.1938
3x 7.62 mm DT machine guns
Unspecified flamethrower
6 35 km/h Front upper plate: 140 mm
Side plate: 125 mm
Turret: 125 mm
Top and belly: 50 to 40 mm
N/A Kreslavsky KV-4 92.6 9
4
3.225
107 mm ZiS-6
45 mm Mod.1937 20-K coaxial
3x 7.62 mm DT machine guns
6 45 km/h Turret: 130 mm
Front hull plate: 130 mm
Front upper plate: 80 mm
Side plate: 125 mm
Rear plate: 130 mm
Top /bottom: 50 -40 mm
N/A Kruchenykh KV-4 107.7 9.13
4.03
3.78
107 mm ZiS-6
45 mm 20-K
4x 7.62 mm DT machine guns
9 30 km/h Front: 130 mm
N/A Mikhailov KV-4 86.5 9
3.6
3
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

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 designed by Sychev. Interpretation and illustration by Pavel Alexe, funded through our Patreon.

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
Total Production 0, blueprints only

Sources:

Breakthrough tank KV – Maxim Kolomiets
Supertanki Stalina IS-7 – Maxim Kolomiets
KV 163 1939-1941 – Maxim Kolomiets
Confrontation – Ibragimov Danyial Sabirovich
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
Tank building on the verge of common sense | Warspot.ru – Yuri Pasholok
Large caliber for large HF | Yuriy Pasholok | Yandex Zen – Yuri Pasholok
“Без огонька” (livejournal.com) – 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
Museum of History of SPbPU (spbstu.ru)
Tanks are a war of minds. Designer of combat vehicles (wikireading.ru)

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