Author: Pavel Alexe

Object 212 SPG

Object 212 SPG illustrated by Pavel 'Carpaticus' Alexe

Soviet Union (1940-1941)
Heavy Self-Propelled Gun – Only Components Built

Even after the KV-2 entered service with the Soviet military, its mediocre concrete penetration still left the Soviet artillery units craving for a more powerful bunker buster after the encounters with the Finnish Mannerheim Line. Development would lead to the Object 212 SPG, but due to the start of the war with Germany and no immediate need for such a vehicle, progress would slow down until it was canceled completely.

Cracking the Mannerheim Line

The Winter War (November 1939 – March 1940) between the Soviets and Finnish taught both sides a series of lessons on fighting a modern war. For the Soviets, this meant incorporation of armor and penetrating the heavily fortified lines of the Mannerheim defensive line on the Karelian Isthmus. Its construction began in the early 1920s, but those segments were poorly built and out of cheaper materials, such as wood. A second plan of building the line started in 1932, which included concrete bunkers with underground sections. Fixed gun mounts of various calibers, trenches, and traps, such as anti-tank pyramids and barbed wire, were meant to funnel attacking troops towards well dug-in defenders. These defensive features combined with the marshy area, with either bogs, lakes or thick forest in winter time, posed a difficult fighting area for the attacking Soviet troops. The line managed to delay the Soviets for a few months.

The three layers of the Mannerheim Line on the Karelian Isthmus, the main line in dark blue, intermediate line in lighter blue and final line in very light blue, towards the north.
Source: S. Korhonen via Winterwar.com

The biggest problem were the “millionaires” (hinting at the cost), as the Soviets would call them, which were large, complex, and thickly armored bunkers built in the period before the war. For combating these, the most effective way was artillery fire from the massive 152 mm BR-2 howitzer, capable of penetrating 2 m of concrete. However, the system was incredibly large and cumbersome. Transporting the tracked howitzer through the rough terrain was a logistical nightmare.

BR-2 tracked howitzer firing during winter time.
Source: Topwar

The 1930s were a period of considerable maturing of the Soviet armored forces, and the Winter War would be a great testing area for various Soviet tanks, such as the serially built T-26, T-28, and BT-series light tanks, but also various prototype and projects built for the needs created by the war, such as the Object 217 (PPG), SMK, T-100, and KV tank. The KV (U-0) specifically would see action in December 1939. The tank was armed with a main 76 mm L-11 gun and a secondary 45 mm one in a small turret, which was removed on serially produced tanks. After unpleasant experiences with Finnish fortifications, on 11 January 1940, the Leningrad Kirov Plant (LKZ), the builder of the SMK and KV tanks, was asked to develop a tank mounting the M-10 152 mm howitzer. The conversion was made by developing a larger turret on the KV with the M-10T howitzer (the T meaning that the gun was adapted for use in an AFV). It was originally just called KV with a big turret, but was later named KV-2. Several prototypes/early vehicles of the KV-2 would see service against the Finns.

The first KV-2 (KV with big turret) prototype U-3. It was meant to carry a large howitzer for ‘bunker busting’, but the 152 mm M10T was too weak for both concrete and armor penetration.
Source: Juri-rust

Early Bunker Busters

While the KV-2 was being tested in battle, on 17 January 1940, a decree from the Soviet Defense Committee was signed. Plant No.185 was also tasked with continuing their projects on the SU-14 by installing the 152 mm BR-4 inside. The SU-14 was a troubled self-propelled gun project dating back to summer 1933, but due to various reasons, only two were built and tested. The project involved taking the two open-topped self-propelled guns based on the T-35 heavy tank and armoring them, giving them the capability for direct fire from closer ranges, though it was estimated that the average combat range would be between 1.5 to 2 km. The vehicles were given up to 60 mm of armor frontally, increasing the total weight to 64 tonnes, and were renamed to SU-14-2. Despite the progress, the Izhora Plant was only able to deliver the first vehicle by 13 March, a day before the end of the Soviet-Finnish War. The two vehicles were still tested at Kubinka and would partake in the defense of Moscow, but would never enter mass-production.

The only surviving SU-14 (SU-14-2, the armored version shown here) at the Kubinka Tank Museum. It has since been moved to the nearby Patriot Park.
Source: Wikimedia Commons

During the same period, Plant No.185 would not only upgrade its previous SPGs, but also design new vehicles. Their T-100 tank, a competitor to the SMK, would become the basis for heavy gun carriers. Firstly, as a response to the KV-2, the T-100 was fitted with a larger turret and M-10T howitzer and named T-100Z. Additionally, three other projects based on the T-100 were designed to equip the 130 mm B-13 gun, which had a lighter and faster firing shell with similar ballistics. The first two were the T-100X and T-100Y, which replaced the two turrets of the T-100 with a large fixed casemate. The T-100Y was to be built, but it was delivered by the Izhora Plant only on 14 March and thus would not be tested against Finnish “millionaires”. The third project, T-103, was meant to equip the B-13 gun in a large turret, but the project was abandoned after a mock-up was built.

T-100Y, renamed in 1945 to SU-100Y, displayed at Patriot Park.
Source: Patriot Park

Development

The conclusion of the Winter War marked the end of the immediate need for heavy bunker busting vehicles, but they were still seen as a long-term necessity. Thus, on 10 April, testing of the Factory 185’s SU-14-2 and T-100Y commenced. However, due to the archaic chassis of the SU-14 and failure of the T-100 heavy tank, both self-propelled guns were doomed. Attention shifted back to LKZ, and while the KV-2 was a quickly designed vehicle that was forced into service before it was properly tested, it was far from what the Soviet artillery forces needed. The M-10T howitzer had mediocre concrete penetration, 900 to 1,140 mm of reinforced concrete from 1,000 m distance.

On 17 July 1940, LKZ would be tasked with developing a series of new heavy tanks based on the KV tank. In total, there would be four heavy tanks, with 90 mm to 100 mm of armor, as well as being armed with 76 mm and 85 mm main guns. Additionally, a heavy self-propelled gun was also requested, based on the chassis of these new heavy tanks, and armed with the 152 mm BR-2 howitzer.

These heavy tanks would become the T-150, T-220, and T-221, the first two which were built in the fall of 1940 and tested in January-February 1941. The T-220, which was a lengthened KV-1 (seven roadwheels) and 100 mm of armor all around would become the basis for the self-propelled gun.

The T-220, more commonly known as the KV-220, was a lengthened KV-1 with an enlarged turret, housing the 85 mm F-30 gun. It would originally serve as the basis for the Object 212 SPG.
Source: Warspot, colorized by johannes Dorn

It is worth mentioning that, during the same period, the mounting of large caliber howitzers (122 mm, 130 mm, 152 mm, and 180 mm) on the chassis of the SMK was also explored, as a document from 11 June specifically requested the 152 mm BR-2 be mounted on the SMK. Likewise, the idea of mounting the 152 mm BR-2 on the T-100Y was also raised, but by summer 1940, both the SMK and T-100 chassis were dead for good and these plans never went past proposal stages.

On the other hand, the KV-1 and KV-2 would enter full-scale serial production in June 1940 after the implementation of the “Stalin Task”, which demanded the yearly production of 230 KV tanks (130 KV-1s and 100 KV-2s). It seemed as if the KV chassis was the optimal choice for a heavy bunker busting SPG, and there were doubts even about the development of such a vehicle, considering the expected high numbers of KV-2s in the upcoming future.

Development of the self-propelled gun started in August-September 1940 at SKB-4, the LKZ artillery design bureau, headed by P.F. Fedorov, who appointed Ts.N. Golburt as the chief engineer of the project. Design of the hull was done at the SKB-2 design bureau instead, as they had more experience with heavy tanks and designed the KV-220. The self-propelled gun would be based on the Object 212 artillery tractor, and would receive the same name, though some modern resources add the suffix “A” at the end (Object 212A) to make the distinction, though this was never official.

Object 212 Tractor

The original Object 212 tractor was a proposal designed between January and February 1940. It was a 35-tonne recovery tractor on a heavily modified KV chassis, meant to tow knocked-out tanks, as well as for supply and logistics support. The project was never approved for production. It was designed at the SKB-2 design bureau with chief engineer N.V. Khalkiopov. Early blueprints, from 9 February, show that the tractor was to have the final drive towards the front of the vehicle, with the 3 man crew and engine in the center. The rear was reserved for a flatbed for storage. Although derived from the KV tank, all of the components were unique, from the running gear and return rollers, to the hull.

The drawings of the Object 212 tractor, 9 February. Note the new shape and hull components.
Source: Heavy Tank KV

However, by May 1940, the design was changed to use an inverted KV-1 hull, with KV-1 components. The driver was moved to the extreme left of the hull, to allow for the engine and driveshaft. Other small differences, such as the addition of a sprocket guard, were added. Sometime thereafter, a full-scale wooden mock-up of the hull was built. The same general layout was kept as on the earlier tractor. The Object 212 tractor was canceled after the SKB-2 transition to ChTZ.

Front view of the Object 212 tractor, which would serve as the layout inspiration for the Object 212 SPG.
Source: Heavy Tank KV

Other view of the Object 212 tractor. Note the 6 roadwheels, as on the KV-1 tank.
Source: Heavy Tank KV

Further Development

The technical drawings of the 212 SPG were completed and signed by Kotin on 5 November, but the 1 December deadline set by the GABTU (Main Directorate of Armored Forces) was not met. Furthermore, LKZ officials Goldburt, Kotin, and P.F. Federov sent a ‘complaint’ letter to the GABTU Artillery Office on the topic of the technical requirements. Firstly, they claimed that keeping the vehicle at a weight below 55 tonnes while still packing 75 mm of frontal armor was not possible. Alternatively, they proposed that the weight threshold be increased to 65 tonnes, but still the vehicle would only receive 60 mm of frontal armor. The Artillery department had to back down and accept these measures.

In a letter dated December 1940 from Major General Slavchenko, Deputy Chief of GABTU, to Lieutenant General T. Fedorenko, Chief of the GABTU, reported the status of self-propelled gun developments at LKZ. Firstly, the first prototype of the Object 212 SPG was projected to be finished by April, with 12 units built by 1 October. Secondly, the mounting of the B-13 130 mm gun on a SPG chassis (likely the same as on the Object 212) was also mentioned, with the first prototype to be complete by 1 May and 12 pieces to be built by 1 November. The 130 mm naval B-13 which had previously been mounted on the T-100 series of heavy SPGs would now get a second chance, being mounted on a KV chassis.

Drawing of the Object 212 SPG. Note that the drawing lacks several details, such as exhaust, rear door, or machine gun.
Source: Warspot, edited

The project of the 212 SPG was completed by January and the drawings and documentation were sent to the Izhora Plant for prototype manufacturing. By 5 March, the Izhora Plant started to deliver components from the same batch as the two T-220 and T-221, but assembly was delayed in a sudden turn of events.

On 11 March, the Soviet intelligence services submitted a report on German tank developments, which included the alleged design of a Mark VII heavy tank, with 105 mm gun and 90 tonnes of weight (Pz.Kpfw.VII Löwe). Other heavy tanks included the Mark V and Mark VI heavy tanks, with weights of 36 and 45 tonnes respectively. The Soviet officials scrambled towards designing a Soviet equivalent, and thus the KV-4 (Object 224) began its development, with a weight of 75 tonnes and 107 mm main gun.

On 7 April, more heavy tanks were proposed, namely the new KV-3, also known as Object 223, which used the hull of the T-221 (up-armored to 120 mm) and an entirely new turret and 107 mm gun. Lastly, a 100 tonne heavy tank with 170 mm of frontal armor was also requested, the KV-5 (Object 225).

As the new KV-3 was to essentially replace the T-220, while still having an nearly identical hull (the only difference was the 120 mm of armor instead of 100), the Object 212 SPG would now reuse the hull of the KV-3, though no major changes were required.

Mock-up of the KV-3 (Object 223) on which the 212 SPG would be based on later.
Source: Warspot

From Bunker Busting to Lion Hunting

In wake of the German heavy tank developments, Marshal of the Soviet Union G.I. Kulik would send a letter on 17 April to Stalin. Kulik, who was supervising work at LKZ, claimed that the BR-2 gun on the Object 212 in development could be used against heavily armored tanks effectively, penetrating 155 mm of armor at 2,300 m. Likewise, he mentioned the development of the self-propelled gun armed with the 130 mm B-13, but this time on the lengthened chassis of the KV-4. An unspecified high-power 107 mm gun was also under consideration.

It must be noted that the KV-4 Marshall Kulik mentions was likely a mistake or confusion on his part and could not have been the KV-4 super heavy tank, the design of which was not completed until early May. The two SPGs with 130 mm and 107 mm guns were to be built by 1 September and 1 October respectively. This is confirmed at the end of Kulik’s letter, which states that the two tank destroyers were to use the same chassis as the 152 mm howitzer variant (Object 212). Lastly, Marshall Kulik mentions that the original Object 212 prototype would have to be finished on 1 June, allowing for production for the remainder of the year. Another option is that Kulik simply misspelled or confused the KV-3 and KV-4. Realistically, the KV-4 would wind up being so large there was no point in enlarging it for mounting these bigger guns. Likewise, an SPG based on it would have weighed far more than 55 tonnes, considering that the heaviest KV-4 design, by G.V. Kruchyonyh, weighed 107 tonnes, and the lightest, designed by N.L. Dukohv, weighed ‘just’ 82.5 tonnes.

The SPG armed with the 130 mm B-13 was to have a weight of 55 tonnes and thus be lightly armored, at only 30 mm all around the casemate, with adequate protection against shrapnel and diving aircraft attacks. This vehicle is commonly known today as the SU-B-13, though it was not an official name.

The other vehicle was also meant as a tank destroyer and to be equipped with an unspecified high power 107 mm gun, likely the ZiS-24 or M-75, but the vehicle never went past the proposal stage.

Regarding developments on the Object 212, activity was stagnant from March to April. On 27 May, it was confirmed that the 212 SPG would now use the KV-3 (Object 223) chassis instead of the T-220. Whether this means that the Object 212 SPG would have inherited the KV-3’s 120 mm of hull armor as opposed to the original 100 mm on the T-220 is unknown. Delivery of the first prototypes was once again postponed to August, with 12 vehicles to be built and later cut down to 10.

On 30 May, a report on the costs of KV heavy tank projects was published, and here, the 212 SPG was mentioned. In total, it cost 2 million rubles, the equivalent price of four KV-1 mod.1941 tanks.

Stage of Object 212 SPG Development	Price (thousands of rubles)
Draft drawings	100
Scale models	25
Technical drawings	300
Prototype construction and factory trials	1100
Proving ground trials	100
Drawing correction after trials	75
Repair of prototypes and improvements	300
Total cost	200

Source: CAMD RF 38-11355-101

Design

The design of the Object 212 self-propelled gun was very different from any previous vehicles, as it was based on the combination of 212 tractor and the T-220 heavy tank. As remnants of the 212 tractor, the engine and final drive were in the front of the hull, with the idler towards the rear. The platform that was previously used for transport was lengthened, as the chassis was now borrowed from the T-220, and fitted a very large armored casemate, housing the crew and the BR-2 howitzer.

The vehicle is claimed to have resembled the SU-14 in terms of general design, but it might just be pure coincidence. Mounting a large howitzer and its crew towards the rear of the hull offers more internal room, better recoil management, and less frontal gun overhang.

Cutout view of the 212 SPG showcasing the internal components. The gunner’s ‘cupola’ on the casemate roof and ammunition stowage on the hull floor are noteworthy.
Source: Warspot, edited

External view of the hull and several joints of the armor plates.
Source: Warspot, edited

Internal view of the hull with specific joints and structural supports. Note the large gun frame in the hull.
Source: Warspot, edited

Crew

The exact crew details were never specified, but based on the type of vehicle, at least seven men were required: commander, driver, radio operator, two gunners, and two loaders. Although the BR-2 field howitzer used a crew between 10 and 15 men, a lot of this manpower went to preparing the vehicle for transport, ammunition supply, and other logistical difficulties, which would not exist on a self-propelled chassis. Furthermore, a larger crew would have been unbearable in the large, but enclosed casemate.

The driver was positioned to the extreme left of the chassis, to the left of the driveshaft, as opposed to the center on the KV-1, due to the engine and driveshaft now occupying a large volume inside the hull. The radio operator likely sat behind the cooling system and operated a 71-TK-3M radio. The tank commander and the gun operators would stand in the casemate. The commander would have a slightly elevated ‘cupola’ with a PTC rotating periscope for vision, to the right of the gun. The main gunner would sit on the left side of the gun and had 3 fixed periscopes, main gun periscope, and a PTC rotating periscope, for a total of seven periscopes in the casemate. For self-defense, four firing ports were made on the side walls and one 7.62 mm DT machine gun was mounted in a ball mount on the rear wall. For entry and exit, two to three hatches were mounted on the top, as well as a door on the rear wall, for easy entry/exit and ammunition resupply.

Propulsion

The 212 SPG had a V-2SN, a centrifugally supercharged variant of the standard V-2 12-cylinder diesel engine, outputting 850 hp. It was developed by Plant No.75 for the T-220 heavy tank. During its testing on the tank in January-February 1941, the engine was still unfinished and would prove to be a disaster. It lasted for 5 hours and 51 minutes or 106 km on the nearly 63 tonne heavy tank, the tank reaching a top speed of 21.2 km/h. Fuel consumption was 15.5 liters per hour or 0.83 l per 1 km. Wearing out of the pistons squirted hot oil and led to power loss, stopping the trials. Due to the lack of a spare engine, the trials were terminated.

The 700 hp V-5 mounted on the T-150 would suffer a similar fate, but with slightly better results. Due to the engine plant’s inability to provide engines for the new heavy tank projects, the trials of the T-150 and T-220 were postponed until Plant No.75 could fix these issues.

The KV-3 (Object 223) heavy tank, which would become the chassis for the 212 SPG when the T-220 was canceled, was also meant to equip the same engine.

The fuel tank capacity on the 212 SPG was of 845 liters, for an estimated road range of 200 km.

Multi view drawing of the V-2SN engine installed on the Object 212 SPG.
Source: Warspot, edited

Cutout view of the engine compartment, showing the final drive, engine to the right of the hull, driver’s position to the left and cooling system behind him.
Source: Warspot, edited

Main Armament

The most important element of a self-propelled gun is its main armament. For the Object 212 SPG, this was the 152 mm BR-2 Model 1935. The field gun counterpart was particularly controversial. It weighed over 18 tonnes, had a maximum road speed of 15 km/h, and took a 15 man crew 25 minutes to set it up from marching position into firing position with maximum firing elevation. Additionally, by the start of the invasion of the USSR, only 37 pieces had been built, of which only 27 were in active service. Other concerns were the poor horizontal traverse of just 8° towards each side and 100 round barrel life. The latter was fixed in 1937 with deeper riflings. The gun would still see intensive use, from the Siege of Leningrad all the way to shelling Berlin. After modernisations in the 1950s, the guns would be used all the way into the 1970s. The rate of fire was a standard 1 to 2 rounds per minute and maximum range was around 25 km.

The advantages of mounting this cumbersome but otherwise very powerful gun on a tank chassis were obvious, hence the Soviet Artillery department’s wishes for one. The low towing speed and long setup time could be vastly improved, while the thick armor of the vehicle would allow for flexibility in operation, whether it would be close-range support or indirect fire.

However, the mounting of the gun inside an enclosed casemate would have certain negative side effects. Firstly, the tight operating space could have decreased rate of fire and made it a cramped space to be in, but still better than being exposed to the elements and enemy counterbattery. Additionally, as seen on the SU-14, a casemate significantly decreased the elevation angle of the gun, from 60° to 30°, while in the case of the Object 212 SPG, it decreased to just 15°, making indirect fire virtually impossible. This was not seen as an issue, as the vehicle was meant for direct fire support. Gun depression was -3°.

The vehicle was equipped with a respectable 47 two-part rounds for the main gun. In comparison, the SU-152 had 20 rounds. The shells were stowed in the rear corner of the vehicle floor, as well as on the casemate sides. Loading was assisted by a bracket for resting the rounds on. Ammunition for the single 7.62 DT machine gun was 3,000 rounds.

Comparison chart of the KV-2 and Object 212 SPG main guns
Name	M-10T	BR-2
Caliber	152.4 mm	152.4 mm
Muzzle velocity m/s	400-500	880
Shell weight	40 kg	49 kg
Explosive weight (kg TNT)	5.3-5.8	6.5 -7
Penetration (armor)	72 mm @ 60° from 1,500 m	155 mm from 2,300 m
Penetration (reinforced concrete)	900-1,140 mm from 1,000 m	1,500 mm

Komintern tractor pulling the BR-2 howitzer in the transport configuration during a parade.
Source: Topwar

Br-2 152 mm Howitzer on Turreted KV Chassis

Sometime during spring 1941, Kotin, with SKB-2 engineers L.E. Sychev and A.S. Ermolaev, went on a day trip to study naval guns of ships at the Baltic Fleet. There, they inspected the battleship Marat and a Kirov-class cruiser, as well as various other ships. Several systems were analyzed, including gun mounts, loading systems, and ammunition stowage mechanisms. The goal was to incorporate naval guns on tank chassis. One of these projects was mounting the Br-2 152 mm howitzer inside an armored turret and onto a KV chassis (likely also KV-220/KV-3).

Unfortunately, not much is known about this project, aside from the recollections from SKB-2 engineer, K.I. Buganov:

“Before the war, we worked on a hull for a self-propelled artillery installation based on KV with the placement of a 152-mm Br-2 naval gun in its armored turret. The car turned out to be two tons heavier than the calculated one, and Joseph Yakovlevich asked me: “Do you have any proposals for weight reduction?” I said, if you reduce the distance between the engine and the gearbox, you can reduce the length of the car by 500 mm. Reduce the length of the sides, roof, bottom, tracks, and this will give great weight savings. Joseph Yakovlevich said only one word “good”, and then instructed to rework the drawings, regardless of the fact that tracing papers had already been released, that is, essentially the work had ended. Joseph Yakovlevich always quickly grasped the main thing, and if he saw a technical benefit, he never stopped before the difficulties of rework.”

Unfortunately, no drawings of the vehicle are known to survive. The project likely did not survive summer 1941, and was undoubtedly a very challenging feat to fit the Br-2 in a rotating armored turret and still be capable of firing.

Fate

The German invasion of the Soviet Union on 22 June did not have much effect on the 212, which had effectively been frozen in development for nearly 5 months. An attempt to cancel the project would infuriate the head of the Artillery Department, Colonel-General V.I. Khoklov, which after one-and-a-half years, still did not get an improvement over the KV-2 in terms of direct fire bunker busting.

By August, the German forces were approaching Leningrad, the city where LKZ was based and so most of the engineers and projects were transferred to ChTZ in Chelyabinsk, which would be renamed to ChKZ (Chelyabinsk Kirov Plant). Some tank projects were canceled, like the KV-4 and KV-5, while the KV-3 was to continue development at ChTZ. The prototypes of the KV-220 and T-150 would be pressed into combat service at such a desperate time.

The Object 212 had a different fate. It was transferred to the Ural Heavy Engineering Plant (UZTM) in modern day Yekaterinburg. The design bureau, headed by F.F. Petrov, had plenty of experience on artillery pieces and just started producing KV-1 tanks as a subcontractor to ChTZ. On the other hand, this was their first encounter with a tracked SPG project. A.S. Ryzkhov was appointed Head of the Object 212 project.

In October, UZTM sent a letter to ChTZ requesting material and components of the KV-3 to be able to start concrete work on the 212 SPG. The problem was that ChTZ was not working on the KV-3, which had been transferred from LKZ, but it was frozen.

The Object 212 would have its final breath in November 1941, when it was noticed that the switch from tractor production to KV production at ChTZ would mean no more tractors to tow artillery, and thus self-propelled guns were necessary, of which the Object 212 was first mentioned.

However, by December 1941, the KV-3 was virtually canceled and focus at ChTZ went towards other vehicles. Without the enlarged hull of the KV-3, UZTM could not build a prototype and the project was canceled as well.

Interestingly, in March 1942, Experimental Plant No.100 was appointed to design and develop a 152 mm BR-2 heavy self-propelled gun on a KV chassis, the bunker buster. Plant No.8 was responsible for the gun mount. 1,500,000 Rubles were assigned to the project, but the death of the KV-3 and complexities of lengthening the KV-1 chassis doomed it as well.

Various heavy self-propelled gun designs on KV chassis would be drawn out in the following period by several design bureaus, but it was not until 1943 that the Soviets could field one, in the form of the SU-152, armed with the ML-20S 152 mm howitzer mounted on the KV-1S chassis.

Conclusion

The Object 212 was a very promising project on paper. The ability to improve the BR-2 howitzer’s main drawbacks and mount it on an armored chassis would have proven very beneficial. However, the project was on a rough route right from the start. The end of the war with Finland meant that there was no immediate need for such a vehicle, while the mass-production of the KV-2 could (on paper) fulfill the same role already. Lastly, the vehicles it was intended to be mounted on, the T-220 and KV-3, were too heavy and unreliable, and with the start of the war with Germany, the Soviets could not afford to spend time and resources on uncertain projects. The need for a self-propelled gun armed with a potent 152 mm howitzer would persist well into the war, until the SU-152 would enter service.

Object 212 SPG illustrated by Pavel ‘Carpaticus’ Alexe

Object 212 SPG Specifications
Dimensions (L-W-H) (approx.)	7.90 x 1.92 x 2.57 m
Total weight, battle-ready	65 tonnes (50 tonnes without ammunition, fuel and equipment)
Crew	7 (Commander, driver, radio operator, 2x gunners, 2x loaders)
Propulsion	V-2SN 12-cylinder supercharged diesel, outputting 700 hp.
Speed	35 km/h hypothetical
Suspension	Torsion bar, 7
Armament	152 mm BR-2 howitzer Single 7.62 mm DT machine gun
Armor	Front: 60 mm (75 mm originally) Sides: 60 mm Rear: 45 mm Roof: 20 mm Belly: 20-30 mm
	Some components built

Sources:

Breakthrough tank KV – Maxim Kolomiets
Supertanki Stalina IS-7 – Maxim Kolomiets
Victory Tank KV Vol.1 & 2 – Maxim Kolomiets
Constructors of Combat Vehicles – N.S. Popov
Domestic Armored Vehicles 1905-1941 – A.G. Solyakin
Bronevoy Schit Stalina. Istoriya Sovetskogo Tanka (1937-1943) – M. Svirin
Heavy Tank KV – M. Baryatinsky
About the forgotten creators of Soviet armored power. (historyntagil.ru) – S.I. Pudovkin
Pillbox Hunter | Warspot.ru – Yuri Pasholok
Вторая жизнь устаревших шасси | Warspot.ru – Yuri Pasholok
КВ-3: набор танковой массы | Warspot.ru – Yuri Pasholok
Опытный танк с боевой биографией | Warspot.ru – Yuri Pasholok
The history of the Mannerheim Line, part 2 (winterwar.com)
Tank Archives: Heavy Trials – Peter Samsonov
Tank Archives: Heavy Tank Costs – Peter Samsonov
Tank Archives: Kirov Factory Prototypes, March 1941 – Peter Samsonov
152-mm gun Br-2 model 1935. USSR (victorymuseum.ru)

WW2 Soviet Heavy Tank Prototypes

Object 222 (T-222/KV-3/KV-6)

Post author By Pavel Alexe
Post date March 29, 2023
1 Comment on Object 222 (T-222/KV-3/KV-6)

Object 222. Illustration by Pavel Alexe.

Soviet Union (1941)
Heavy tank – Partial Mock-up Built

Even before the T-150 heavy tank entered trials in January 1941, several issues had already been noted and a new turret was designed. Nonetheless, this turret never left the drawing board. A second attempt was made during and after the T-150 trials, and the tank was named Object 222. After impressing the military and state officials, it was named KV-3. The excitement was short-lived, however. In April, heavier tanks, like the Object 223, were designed, and this latter project would eventually get the name KV-3 as well. The Object 222 was then meant to enter production in June 1941, under the name KV-6, but, due to the German invasion of the Soviet Union, this never happened.

The T-150

The KV-1 heavy tank would officially enter production in February 1940, 9 months after the original request for production. Even so, by July, only 32 of the pre-series KV tanks were built, prefixed with the “U” index. The tanks had design issues, along with technical and production problems. The pressure from Stalin to adopt these unfinished tanks grew, and, in June 1940, with the “The Stalin Task”, the Council of People’s Commissars of the Soviet Union would order the increase of the yearly production quota of the KV to 230 units of both variants (130 standard KV-1 and 100 KV-2s with 152 mm howitzers). The Leningrad Kirov Plant (LKZ), barely able to keep up with the previous production rate, was ravished. Corners had to be cut in order to streamline and speed up production, while the tanks were still being tested and improved on the go. This cutting of corners would later come to bite the Soviet officials and factory designers in the back, as the KV-1 would prove to be unreliable and cumbersome on the battlefield.

The desire for heavier tanks based on the KV-1 appeared in May 1940, and by 17 July, the Main Directorate of Armored Forces (GABTU) and the People’s Commissariat of Heavy Engineering requested four new tanks from LKZ, more specifically the SKB-2 design bureau. Out of these four tanks, two were to pack 90 mm of armor, of which one armed with a 76 mm gun and one with an 85 mm gun. The other two were to have 100 mm of armor and also be equipped with a 76 mm and 85 mm gun respectively. The latter would become the T-220.

For the 90 mm armor tank with 76 mm gun, the chief designer, Military Engineer L.N. Pereverzev, part of the SKB-2 design bureau, was assigned to design it by August 1940. The new tank was indexed T-150, but the Object 150 and KV-150 names were also officially used. It was to be based entirely on the KV-1 in production, with only the necessary changes made. In order to add the extra 15 mm of armor all around the tank, it was necessary to equip it with a new engine, namely the 700 hp V-5 from Plant No.75. As the thickening of the armor was done outwards, the internal layout and components position of the KV-1 were kept the same. Reinforcements were added to the suspension to better deal with the extra mass, which reached 50.16 tonnes, compared to the 44 tonne KV-1 (autumn 1940). Lastly, and perhaps the largest external change on the T-150, was the addition of a large commander’s cupola, equipped with 6 periscopes and one rotating PTC periscope.

The T-150 was a premature attempt at improving the armor of the KV-1, which was already excellently well armored.
Source: Warspot, colorized by Johannes Dorn

The first prototype was to be built and delivered to LKZ by the Izhora plant by 1 October, but due to overloading difficulties caused by the KV-1 production, the prototype was only delivered by 1 November. During November, after analysis by its designers, a new turret for the T-150 was designed, that would fix certain problems annotated, like the poor commander’s position to the right of the gun. In the new turret, the commander was moved to the back, inside the turret bustle, where he would have a better overview of the battlefield, with 8 periscopes instead of 6, and better communication with the crew. Another problem fixed was the removal of the gunshield above the mantlet, which on the T-150 prototype was poorly made and restricted gun depression. Despite these promising changes, it did not go past the blueprint stage.

Testing of the T-150 would begin on 14 January 1941 and end in February. During this period, several significant issues were discovered. Firstly, the T-150 weighed 50.16 tonnes, over 2 tonnes heavier than the 48 tonne threshold imposed by the GABTU. Secondly, the experimental V-5 engines would prove to be a complete disaster. The chief designer of Plant No.75, T. Chuptakhin, who was present at the trials, was not able to guarantee the operation of the engines installed on the T-150 and T-220 tanks. The T-150 would only operate for 24 hours or 199 km before its engine broke down. It was noted that when driving in high gears (3rd and 4th gear), the injected oil temperature would spike after just 5 minutes even in outside temperatures of 9-12º Celsius.

The turret would prove problematic as well, despite the issues originally being noticed in November. The commander’s cupola was too tall for observation while sitting down, but too low when standing up, forcing the commander to semi-squat in a very straining position. The other crewmembers in the turret were not spared of problems either. The loader, sat behind the commander and to the right of the gun, would be restricted from lifting shells from the left wall by DT machine gun ammunition boxes. The vast majority of the main gun shells were stored in small boxes, which were hard to open, cutting the loader’s hands and getting stuck on one-another. This decreased the rate of fire to 1-2 rounds per minute when loading from the boxes (from 5-7 rounds per minute maximum). Lastly, the gunshield above the mantlet was badly designed and only allowed for 3º of gun depression, instead of the 6.5º intended.

All in all, the T-150 performed as expected considering the rough circumstances, and many of the issues could be roughed up. Despite this, the GABTU and People’s Commissariat of Heavy Engineering were not satisfied with the result and demanded that the turret and engine problems be fixed.

The November 1940 sketch for an improved turret for the T-150. This turret would become the basis for the turret of the Object 222.
Source: Warspot

Development

Before the T-150 trials were even finished, a second attempt at improving the turret was made. Like the first time, the commander’s position was moved to the turret bustle, with a more streamlined cupola, which dropped the PTC rotating periscope but maintained the eight periscopes, as opposed to the T-150’s six. Other changes included the casting of the gun mantlet for faster production, removing the side turret wall gun port and decreasing the size of the gunshield. One of the more controversial changes was the adjusting of the side and rear wall armor to vertical angles, as opposed to 15° inwards. Otherwise, the design would use the same hull as the original T-150. The tank was indexed Object 222.

After review of the project by the GABTU and state authorities, the People’s Commissariat of Defence and the Central Committee of the Communist Party proposed accepting Object 222 into service and giving it the name KV-3. The name KV-3 had previously been used when describing the T-150. The question of propulsion was also raised, but after a commission formed on 21 February, Plant No.75 had to figure out the issues with its engines and make them usable by 10 April. To ensure that the engine would not overheat again, the cooling system of the Object 222 was reworked as well.

The Object 222 was still armed with the 76 mm F-32 gun, but with the same gun being introduced on the KV-1, it seemed like it would quickly become redundant. Thus, it was also proposed that the Object 222 (KV-3) was to be rearmed with the much more potent 76 mm F-34.

On 3 March 1941, a commission was formed, consisting of Military Engineers 2nd Rank I.A. Burtsev and I.A. Shpitanov, Military Engineer 3rd rank Kaulin, LKZ director I.M. Zaltsman, SKB-2 director J.Y. Kotin, director of LKZ 1st dept. A.Y. Lantsberg and NII-48 research institute engineers V. Dalle and A.P. Goryachev. The goal of the commission was to further assess the Object 222 and prepare it for prototype production. The commission reviewed the drawings of the tank as well as a wooden mock-up of the turret mounted on the hull of the KV-1. It was here that the lack of an angle on the side and rear plates was deemed as an issue, decreasing the overall armor protection. Other issues noted was the lack of an entry and exit hatch on the commander’s cupola and vulnerability of the pericopes from damage and enemy fire.

Nonetheless, the commission agreed on producing a turret as per the above in order to have it ready for testing by 1 April. Yet the commission would expect that, by the time of mass production, the turret walls would be angled again. According to the three representatives from LKZ, Zaltsman, Kotin and Lantsberg, the reasons for implementation of vertical walls were:

Improving crew working conditions;
Improving connections between the plates, especially for the roof plate;
Easier manufacturing.

Additionally, they claimed that the sloping brought no true advantages either. Mathematically, the equivalent armor thickness of a 90 mm plate angled at 15° is 93.17 mm, an insignificant gain considering the production complications.

After the commission, on 15 March, the Council of People’s Commissars of the Soviet Union and the Central Committee of the Communist Party gave decree No. 548-232§, which imposed that LKZ had to switch mass production to the KV-3 (Object 222) in August, with 55 units built in the first month, increasing to 105 in September, 110 through October and November, and 120 units in December, for a total of 500 KV-3 tanks in 1941.

The date of delivery was also pushed back after LKZ’s ‘complaints’, and the first prototype was to be delivered by 1 May, and testing to begin on 15 May. To meet this deadline, the Izhora plant had to deliver the experimental turret by 1 April, with LKZ having to deliver drawings of the experimental turret on 20 March, drawings of the hull by March 25 and drawings of the production turret by 10 April. Plant No.203 to deliver the KRSTB radio set and Plant No.69 to deliver optical sights for the DT machine guns.

Design

The Object 222 (T-222/KV-3) was just a T-150 hull with a slightly modified turret. In turn, the T-150’s hull was just a KV-1 hull with a new engine and minor dimension changes due to the thicker armor. The frontal upper plate consisted of two parts, an angled ‘hood’ and a flatter portion, right in front of the driver and radio operator. On it was the headlight, driver’s vision port, and a 7.62 DT machine gun in a ball-mount. Above, on the top deck was a service hatch for the two crewmembers. The running gear consisted of a frontal idler, large rear sprocket, and 6 steel rimmed wheels, sprung by torsion bars, with three return rollers.

The general armor profile was of 90 mm all around, with the exception of the turret roof, which was 40 mm thick, and hull deck, which was 30 mm. With the new turret, the weight of the Object 222 was expected to be slightly higher than that of the T-150, at 51 to 52 tonnes.

The side drawing of the Object 222, armed with the 76 mm F-32 gun, circa February 1940.
Source: Yuri Pasholok

Turret

The new turret differed greatly from the T-150’, but was heavily inspired by the November 1940 T-150 turret upgrade. The gun mantlet was a two-part cast type, and the gunshield was shorter, for improved gun elevation and depression angles. The design of the turret walls was altered as well, with larger flat side and rear plates and potentially a rear turret door, like on the KV-2 and T-220, though this is unconfirmed. The rear-facing 7.62 mm DT machine gun mount was kept, though the ball-mount design was changed as well. Other minor changes to the turret included strengthening around the gun mantlet side-front plate connection and the replacement of side gun port and vision slit with a small hatch.

The most important change was the relocation of the commander, to the back of the turret. The position of the T-150’s commander was noted as an issue already in November 1940, thus the first turret upgrade design also placed the commander in the back. Likewise, the trials of the T-150 criticized the position of the commander and suggested moving him to the rear. However, after the commission analysis of the Object 222 turret, it was not deemed as ideal. Additionally, the lack of an entry-exit hatch for the commander and no protection ring for the periscopes were also deemed as an issue. To fit the commander in the turret overhang, a large groove was made along the connection between the turret ring and the turret overhang bottom plate, to allow the commander to sit on.

Internal cutout view of the Object 222. Note the position of the F-32 gun ammunition in the turret bustle.
Source: Stalin’s Supertanks IS-7

Crew

The crew consisted of 5: commander, gunner, loader, driver, and radio operator. The commander sat in the turret bustle, from where he could communicate with the loader and gunner. For vision, he had a cupola with 8 periscopes. He would also operate the rear facing machine gun, should the situation call for it. The gunner sat to the left of the gun, and had his primary gun sight and a PTC rotating periscope for general vision. A second fixed periscope was placed on the side of the turret, like on most KV tanks. The loader sat to the right and rear of the gun, and would load shells from both sides of the turret walls and those stowed in the hull floor. He was no longer responsible for the rear-facing machine gun.

The positions of the crew in the hull was unchanged from the KV-1, with the driver in the center and the radio operator to his left. The radio was a KRSTB, an early version of the 10-RT radio, but it was possible to install the standard 71-TK-3 radio.

Commander’s position on the November 1940 turret upgrade of the T-150. Some of the changes were incorporated into the Object 222.
Source: Warspot

Propulsion

The engine of the Object 222 was to remain the V-5 engine, as on the T-150, but in a functional form and with a redesigned cooling system. The V-5 engine had been developed at Plant No.75 by boosting the V-2K 600 hp engine, which itself was an already boosted and unreliable variant of the V-2. The V-5 was a four-stroke 12-cylinder diesel engine outputting 700 hp. The fuel tank had a 700 liter capacity, offering the tank a range of 250 km or 10 work hours. Maximum speed was a mere 35 km/h on road and off-road, 15 to 20 km/h. The tank had a warranted distance between major breakdowns of 2,000 km.

Armament

Initially, the main armament was to remain the 76.2 mm F-32, as on the original T-150 and which just began incorporation on serially produced KV-1s, replacing the L-11 gun. But during discussions in February, it was proposed to rearm the Object 222 with the much more potent 76.2 mm F-34. The tank carried 114 shells for the 76 mm gun and 2900 rounds in 46 drums for the DT machine guns. The main difference between the F-32 and F-34 guns was the muzzle velocity and penetration. For example, the same shell, BR-350A (APHE) had 615 m/s muzzle velocity in the F-32 and 662 m/s in the F-34. Likewise, the OF-350 (HE) had 615 m/s muzzle velocity on the F-32 and 680 m/s on the F-34. The F-34 gun was mounted on the T-34 tank in early 1941, with the KV-1 adopting it only much later as the ZiS-5 gun.

	F-32	F-34
Caliber (mm)	76.2	76.2
Muzzle velocity (m/s)	615	662
Shell weight (kg)	6.3	6.3

The tank was armed with two 7.62 DT machine guns, one in the hull for the radio operator and one in the back of the turret. The KV-1 and T-150 also featured a coaxial machine gun, but it was dropped on the Object 222, as the commander was moved and due to the new gun mantlet.

Fate

Between 7-9 April, the LKZ heavy tank development programs were altered, as the need for more powerful heavy tanks was assessed. The KV-3 name would be given to a new tank, based on the up-armored chassis (120 mm frontal armor) of the Object 221, and named Object 223, as well as receiving an entirely new turret armed with the 107 mm ZiS-6. Furthermore, a 100-tonne tank was also requested, with 170 mm of frontal armor and also armed with the 107 mm ZiS-6 and was named KV-5 (Object 225). The LKZ factory was still meant to build a prototype and begin prototype production by June, but with three heavy tank developments ongoing simultaneously with tight deadlines. Based on the production quota report for LKZ, 500 KV-3 (Object 223) tanks should have been built from August 1941 to the end of the year.

The KV-3 (Object 223). Despite also being named KV-3, the Object 223 was a serious upgrade over its predecessor.
Source: Warspot

On 5 May, Marshal G.I. Kulik and Lt. Gen. Y. Fedorenko came to the Central Committee of the Council of People’s Commissars of the Soviet Union, requesting the switch to the KV-6 (Object 222) as opposed to the KV-3 (Object 223). Historian Maxim Kolomiets also mentions here that the KV-6 was also armed with a flamethrower with 15 rounds (10 liters) and that the vehicle was actually the T-150, though that is improbable.

The situation worsened on 22 June 1941, when the Axis forces began Operation Barbarossa, the invasion of the Soviet Union. Thus, much of the military’s focus shifted to producing, maintaining, and improving existing tanks. Furthermore, by September, German forces were approaching the city of Leningrad and many SKB-2 engineers were evacuated or placed into military maintenance battalions. Those evacuated were sent to the Chelyabinsk Tractor Plant (ChTZ) which was renamed ChKZ (Chelyabinsk Kirov Plant) after this move. Work on the KV-4 and KV-5 would not resume, but the KV-3 would continue to see slow development until December, when it was finally canceled.

The Object 222, (KV-6) would be ordered to start production at ChTZ on 1 January 1942, with LKZ and NKTM officials providing a prototype, while ChTZ sends a team to LKZ to establish the technical details of the design and prepare for its production.

Conclusion

The first KV-3, the Object 222, was just a T-150 with a new turret. Unlike its predecessor, it was much more short-lived, damned by the design and developments of much heavier KV tanks. With hindsight, the Object 222 was a genuinely good design on paper, and a mature improvement of the KV-1. Sadly, the Object 222 remains overshadowed to this day by more ‘exciting’ designs, like the T-220 and Object 223, the latter KV-3. Only a turret mock-up was built, which was likely destroyed during the war.

Object 222. Illustration by Pavel Alexe.

Object 222 (T-222/KV-3/KV-6) Specifications
Dimensions (L-W-H) (approx.)	6.760 x 3.330 x 3.010 m
Total weight, battle-ready	51 – 52 tonnes
Crew	5 (Commander, gunner, loader, driver, radio operator)
Propulsion	V-5 12-cylinder diesel, outputting 700 hp.
Speed	35 km/h
Suspension	Torsion bar, 6
Armament	76.2 mm F-32 or F-34 3x 7.62 mm DT machine guns
Armor	Front/sides/rear of hull and turret: 90 mm Top/Belly: 30 to 40 mm
No. Built	Partial mock-up

Sources:

Breakthrough tank KV – Maxim Kolomiets
Supertanki Stalina IS-7 – Maxim Kolomiets
Victory Tank KV Vol.1 & 2 – Maxim Kolomiets
Constructors of Combat Vehicles – N.S. Popov
Bronevoy Schit Stalina. Istoriya Sovetskogo Tanka (1937-1943) – M. Svirin
About the forgotten creators of Soviet armored power. (historyntagil.ru) – S.I. Pudovkin
Малая модернизация КВ | Warspot.ru – Yuri Pasholok
КВ-3: набор танковой массы | Warspot.ru – Yuri Pasholok
Опытный танк с боевой биографией | Warspot.ru – Yuri Pasholok
Tank Archives: KV’s Replacements – Peter Samsonov
Tank Archives: Heavy Trials – Peter Samsonov
Tank Archives: Heavy Tank Costs – Peter Samsonov
Tank Archives: T-150 Revival – Peter Samsonov
Tank Archives: Tank Plans for 1941 – Peter Samsonov
Tank Archives: Mass Breakdown – Peter Samsonov
Tank Archives: KV Gun Upgrades – Peter Samsonov
Tank Archives: Missing Index: KV-6
№ 189. Resolution of the Council of People’s Commissars of the USSR and the Central Committee of the All-Union Communist Party (Bolsheviks) No. 548-232ss “On the Production of KV Tanks for 1941”

WW2 Soviet Heavy Tank Prototypes

T-150 (KV-150/Object 150)

T-150. Illustration by Pavel Alexe.

Soviet Union (1940-1943)
Heavy Tank – 1 Prototype Built

The KV-150, or more commonly named T-150, was an attempt to improve the armor of the KV-1 even before the KV-1 entered mass production. With 90 mm of armor all around and a 700 hp engine, it could have been a better option had it not been for some critical events during its development phase. It was, however, groundbreaking in what would become a series of KV heavy tanks, and the single prototype saw combat service until the end of 1943.

The KV-1

As one of the most iconic and recognizable tanks of the Second World War, the KV-1 (or simply KV, acronym for the People’s Commissar of Defense for the Soviet Union, Kliment Voroshilov), proved to have unmatched armor and a very potent gun at the start of the German invasion of the Soviet Union, on 22 June, 1941. It had been developed in the late 1930s and tested in combat alongside its 2 much larger competitors, the SMK and T-100, during the Winter War. As the latter 2 followed a much more complex and archaic breakthrough tank philosophy, namely multi-turreted “landships”, the KV-1 (at the time U-0) would be selected for further development. It was created at the Kirov Leningrad Plant (LKZ), where the previous T-28 and its own competitor, the SMK, were designed and built.

By 19 December, 1939, production of 50 KVs was ordered, with mass production to begin in 1941. But, during this time, the ugly side of the vehicle started to come to light. Truth is that, by that time, the KV was far from ready for production, and dozens of mechanical problems, mostly caused by the heavy weight, had to be sorted out. However, due to Stalin’s personal involvement and pressure on the project, the KV entered preseries production in February 1940, which were indexed with a “U” prefix. These differed from vehicle to vehicle and were tested thoroughly to diagnose any issues.

The first KV, the U-0, which would be tested in combat on the Karelian Isthmus in December, 1939.
Source: Topwar

Naturally, Stalin’s patience would not last, and in June 1940, in what would be called “The Stalin Task”, a decree from the Council of People’s Commissars of the Soviet Union would increase the yearly production quota of the KV to 230 units of both variants (130 standard KV-1 and 100 KV-2s with 152 mm howitzers). This immediate increase in production strained the LKZ plant into mass producing what was effectively an unfinished tank. Naturally, corners and compromises had to be cut over all fields in order to streamline production and cut costs. As some KVs were built, others were still vigorously tested, and results showed that the reliability of the gearbox and transmission were poor. Although changes were made, this aspect would become the bane of the KV-1’s existence. From February to July, 32 KV tanks had been built, and production would increase to 20 during the month of August and 32 during September.

A KV-1 built during August or September 1940, abandoned during early stages of the Great Patriotic War. It is armed with the 76 mm L-11 gun.
Source: Waralbum.ru

More Armor

As early as May 1940, before the KV-1 even entered its shy mass production, the topic of improving the armor of the KV was discussed both by the GABTU (Main Directorate of Armored Forces) and by the People’s Commissariat of Heavy Engineering, where the LKZ plant was represented at. First mentions of thickening the KV tank’s armor came on 11 June, which claimed the need to up-armor the tank to armor between 90 and 100 mm. Furthermore, on 17 July, 1940, the Council of People’s Commissars of the Soviet Union adopted decree No. 1288-495cc, which stated:

By November 1, 1940, the Kirov Plant will produce two KV tanks with 90 mm of armor: one with a 76 mm F-32 gun, the other with an 85 mm gun. The Izhora Plant will deliver one hull at the end of October, the production of the tank is scheduled to be completed by November 5. The second hull will be made by November 5th.

By December 1, 1940, the Kirov Plant will produce two KV tanks with 100 mm of armor: one with a 76 mm F-32 gun, the other with a 85 mm gun. One hull will be delivered by the end of October and by the end in November.

In comparison to its predecessor, the KV-1, as being built in summer-autumn 1940, had 90 mm around the gun mantlet and 75 mm all around. These were exquisite levels of armor not just for Soviet tank standards, but also internationally, being able to withstand most anti-tank guns. It also put the weight of the KV at 44 tonnes, already a tonne increase from the U-0. The weight of the KV would keep on increasing, peaking at 47.5 tonnes by 1941.

Regarding the armament mentioned in the decree, the KV-1 was equipped, as a stopgap measure, with the L-11 76 mm gun until mass production of the more potent 76 mm F-32 could begin. As for the 85 mm gun, it was likely to be the F-30 gun developed by V.G. Grabin at plant No. 92 in Gorky, based on the 85 mm M1939 52-K. However, it is noteworthy that only one such gun had been built, and its testing had yet to conclude.

The first obstacle that the up-armored KV faced was the KV itself. By July, the design bureau tasked with its development, SKB-2 and the entire LKZ factory were busy producing and improving the KV, with little room to spare for a new development. The situation was worsened by the delayed delivery of the tank requirements from the military to SKB-2.

Joseph Yakvolevich Kotin, head of SKB-2’s design bureau and one of the greatest heavy tank designers of the Soviet Union.
Source: Andrei BT

In August, head of the SKB-2’s design bureau, J.Y. Kotin, made two teams for the development of the two tanks. The 90 mm-armor KV was to be designed by a team led by Military Engineer L.N. Pereverzev and indexed as T-150 or Object 150 / KV-150. All 3 names were used in documents. For the sake of simplicity and consistency, it will be called T-150 in the article, with the exception of direct document translations. At this point, Pereverzev was still rather new to SKB-2, having just graduated from the Military Academy of Mechanization and Motorisation of the Red Army in 1939, and had only worked on the KV-1.

After the start of WWII, being a military officer, Leonid Nikolevich Pereverzev was put in charge of the 22nd Mobile Repair Battalion, dispatched from LKZ, focusing on KV tanks. By the end of the war, he had received a variety of medals and orders for his efforts during the war. In his short tank design career, he had worked on the KV-1, T-150, T-220, KV-3, and KV-4.
Source: Yuri Pasholok

For designing the 100 mm-armored KV, the more experienced L.E. Sychev was appointed as chief designer. This variant would be indexed T-220 or Object 220 / KV-220. Sychev was a tank design veteran. He had worked on his bachelors at SKB-2 and then began his career in the same place, working on the T-28, SMK, and KV-1.

Once SKB-2 had sent over the documents (likely in September 1940) to the Izhora plant, the T-150 faced another issue. The Izhora plant was working at a very high capacity trying to increase its KV tank output. The 4 prototype KVs were to be built at Hall No.2, where 4 KV tanks were already being built at the same time. This meant that the October 1 deadline for the T-150 was missed, but not by much.

The Izhora plant delivered the hull of the T-150 and a turret on November 1 and LKZ completed the prototype by December. The T-220 was completed shortly after.

The T-150 after it was completed (December-January). Externally, it looked like a KV-1, with the main difference being the commander’s cupola.
Source: Warspot, colorized by Johannes Dorn

In November, during the latter stages of the development of the T-150, a new turret was proposed. It moved the commander to the rear of the turret and gave him a low cupola with a PTC rotating periscope. Other aspects remained the same as on the original T-150 turret. Only a simple sketch of it was done, with a slightly more detailed drawing of the new commander’s position. It was not considered, but it was used as the basis of the Object 222’s turret, which was essentially the T-150 with a completely new turret .

The November 1940 sketch for an improved turret for the T-150.
Source: Warspot

New commander’s position on the proposed turret. It was never considered for production but served as the basis for the one on the Object 222.
Source: Warspot

Object 221 – The T-150’s Bigger Brother

As per the request from 17 July, 1940, two tanks were supposed to be built with 90 mm armor, one with a 76 mm gun and one with an 85 mm gun. The first became the T-150, however, the latter had a more troubled development. When researching about the mounting of a 85 mm gun on the chassis of the KV-1, it was realized that it would not fit in the standard KV turret and a larger turret combined with additional armor would require a longer hull. This meant that both the 90 mm and 100 mm variants armed with an 85 mm gun would receive a longer hull, by one roadwheel (a total of seven). The 100 mm armored variant armed with the 85 mm gun became the T-220.

The 90 mm variant was named Object 221 or T-221. It was intended to mount the same turret and 85 mm F-30 gun as the T-220. However, there were serious delays, and the Izhora plant only managed to deliver hull components for the T-221 by 10 February 1941, and the F-30 gun and turret were not ready. On 19 February, Marshall of the Soviet Union G.I. Kulik proposed that the 76 mm F-27 gun be mounted inside a KV-1 turret instead, but nothing was done. The Object 221 remained abandoned until April, when it was used as the basis for the KV-3 (Object 223), though 30 mm of extra frontal armor were required for it to reach the specified armor thickness.

Design

For the most part, the T-150 was identical to the KV-1. As the additional 15 mm of armor were added on the outside of the hull, the internal layout for the crew was unchanged. The main armament was, as requested, a 76.2 mm F-32 gun, coaxially paired with a 7.62 mm DT machine gun to the right of the main gun, with another DT machine gun at the rear of the turret and one in the hull, next to the driver. Both machine guns were mounted in ball mounts.

The weight of the T-150 reached 50.16 tonnes, around 6 tonnes heavier than a KV, and went past the weight threshold by over 2 tonnes. Due to the increased weight, the suspension was reinforced. Otherwise, the hull remained identical to that of the KV-1, with front idler, large rear sprocket and 6 steel-rimmed roadwheels.

The front of the tank had the same features as the KV-1, with 2 tow hooks on the lower plate, a single driver viewport in the center of the upper plate, with a driving light to its right and ball mounted machine gun to its left.

The turret was essentially a KV-1 turret with thicker armor, but certain changes were made to accommodate the commander’s cupola. It was fixed in place and of cast construction. At the front, a fully rotating PTC periscope was mounted, with 6 other triplex periscopes around the cupola. The commander’s cupola likely lacked a service hatch, meaning that the commander and loader would likely have to share a hatch. The turret also featured the standard KV-1 vision devices, a PTC rotating periscope for the gunner and another periscope to the side and 2 facing the rear. Direct vision slits were provided over the machine gun ports. This meant that, on paper, the T-150 offered better vision for the crew than the KV-1. The driver’s vision systems were not changed.

The main novelty of the T-150 was its 90 mm armor all around the turret and hull. The turret deck, hull deck and hull belly were 30-40 mm thick. The commander’s cupola was rather large, but was also 90 mm all around and, thus, was not a weak spot. Frontally, this was a 20% increase in raw thickness over the KV-1 in most areas.

Side view of the T-150. The tarpaulin on the fender was used to cover the turret and gun during trials.
Source: Warspot

Crew

The crew of the T-150 was the same as that on the KV-1, with 5 men: driver, radio operator/bow machine gunner, commander, gunner, and loader.

The commander was seated to the right of the gun, where he would be able to observe the battlefield from his cupola. He was also tasked with loading the coaxial DT machine gun on his side. The gunner sat on the other side of the gun, to the left of the turret. He would aim and fire the gun via a TOD sight. He had a rotating PTC and fixed periscope for external vision. He was able to rotate the turret via an electric system but also with a hand crank. Behind the commander sat the loader, on a removable seat (for easier maintenance/loading). He would load the main gun with shells stored on the side turret walls and in cases on the hull floor. He would also operate the rare turret machine gun, should the situation require.

In the center of the hull sat the driver, and to his left the radio operator, who also manned the bow DT machine gun. The radio was mounted underneath the frontal plate.

Engine and Propulsion

The engine installed on the T-150 (and T-220) was the four-stroke V-5 diesel, 12-cylinder in V-config with an output of 700 hp. It was essentially a boosted V-2K (600 hp), which itself was a boosted variant of the V-2. The main problem was that the V-2K was unreliable and barely guaranteed to work for up to 100 hours. Consequently, the V-5 was even less reliable. So much so that, during trials, the chief designer from Plant No.75 could not guarantee the function of the engines on the T-150 and T-220. Combined with the poor design of the engine’s cooling system done by SKB-2 engineers, the engine would have several major issues during the trials and only worked for 199 km, or 24 hours.

The fuel tank capacity remained the same as on the KV-1, at 615 liters, which reduced the range to 220 km (on roads).

Rear of the T-150 tank.
Source: Warspot

Armament

The main armament on the T-150 was the 76.2 mm F-32 gun. It was developed by Plant No.92 in Gorky in the late 1930s and was tested on the BT-7. It could fire BR-350A and BR-350B (APHE), BR-350SP (AP), and OF-350M (HE). The shell weight varied between 6.2 kg and 6.78 kg, depending on the type. The muzzle velocity was between 613 and 621 m/s (figures vary depending on the source consulted). In January 1941, the KV-1 would enter production with the F-32 gun. It was ballistically very similar to the L-11 it was replacing on the KV-1, while the T-34 would receive the far more potent F-34 76 mm gun the same year.

76 mm F-32 gun, used on the T-150
Source: Sovietarmyforum via Rotor

For proximity and anti-infantry defense, three 7.62 mm DT machine guns were mounted, one coaxially, to the right of the gun, which could be used for ranging closer targets (muzzle velocity around 840 m/s). The front facing machine gun in the bow was for suppression of infantry and the machine gun in the rear of the turret was for defense against flanking infantry.

Trials

On 14 January 1941, the People’s Commissariats of Defence and People’s Commissariats of Heavy Engineering requested that the T-150 and T-220 be tested at the LKZ proving grounds. A commission, headed by the Military Engineer 1st Rank Glukhov and with representatives from the GABTU, would monitor the testing of the tanks. According to the commission for field testing, the following goals were intended.

Determining the tactical and technical characteristics of the tank.

Identifying the shortcomings in the designs and their elimination prior to mass production.

Judging whether it is possible to conduct military tests.

Accumulating data for operating and repairing the tanks.

The T-220 during its trials. It was developed alongside the T-150 from the original request for a KV tank with 100 mm of armor and 85 mm gun.
Source: Tank Archives, colorized by Johannes Dorn

The tests would begin the following day on both tanks. During this time, several issues were quickly identified. On 25 January, the two prototype tanks were weighed, with the T-150 weighing 50,160 kg and the T-220, 62,700 kg. The problem here was that the GABTU specifically requested the T-150 to weigh a maximum of 48 tonnes and the T-220 56 tonnes. A report written by Military Engineer 1st Rank Glukhov on 28 January to the Head of Armored Department of the GABTU, Military Engineer 1st Rank Korobov, in the midst of the trials, showed that the commander’s cupola was poorly made (the observation devices were located too high, vision was inconvenient) and was placed in the loader’s position, who is not in command of the tank. Comically, the Chief Designer of Plant No.75, T. Chuptakhin, who was present at the trials, was not able to guarantee the operation of the engines installed on the T-150 and T-220 tanks. One of Glukhov’s reports included the following passage:

“The T-150 tank, after replacing the engine that failed during the factory run on 21 January, has not yet been brought back to the accepted state required by the Quality Control Department and military representatives.”

The gunshield was crudely made and provides only 3º of gun depression, instead of the 6.5º, as specified by the drawings.”

Due to the breakdown of the experimental V-5 engine provided by Factory No.75, the T-150 traveled only 199 km, or 24 work hours. Several issues were found and once again reported by Glukhov:

“The engine’s oil cooling system prevents the tank from driving at high speeds in the 3rd and 4th gear (at an outside temperature of 9° to 12°, the temperature of the injected engine oil increased rapidly after 5 minutes of motion in 3rd and 4th gears). Normal operation of the engine (inlet oil temp. 70°-80°). Due to the poor design of the cooling system, driving trials on the T-150 would cease.”

The T-150 (left) hooked up to the T-220 (right) during trials.
Source: bronetechnikamira.ru

Instead, focus shifted towards firing trials, especially relevant as the F-32 gun had just replaced the L-11 gun on the KV-1’s production lines. Firing while stationary and firing during short stops went as expected (considering the 4-5 second aiming time), but firing on the move was unsatisfactory, though many of these results were entirely based on circumstances such as terrain and gunner skill, and the gunner conducting the trials, although experienced, was still not entirely familiar with the gun and tank.

Simultaneously, loading times were measured, depending on where the rounds were stowed. When loading shells from the right turret side (9 rounds), 5-7 rounds per minute were sustained. When loading shells from the left side of the turret (9 rounds), the rate of fire dropped to 3 rounds per minute, as the loader had to lean to the other side of the turret. The situation got worse when loading via casings that held 3 rounds. These would have to be lifted up and opened before the shells could be loaded in. This process slowed the rate of fire to 1-2 rounds per minute. In contrast, although not practical, when the shells were simply laid on the floor, 11 rounds per minute could be sustained. Furthermore, the ammunition cases, stowed on the hull floor, would often catch on one another when attempting to lift them, and on 6 separate instances, rounds were jammed inside. The sharp edges of the cases also injured the loader’s hands. Consequently, the commission noted that the ammunition stowage system had to be reworked.

Several issues had been noted with the crew’s positions as well. Firstly, the commander’s seat (combined with the cupola) were criticized for being fixed in place, preventing the commander from viewing out of the periscopes while seated. Likewise, he could not stand, as there was no room, but rather the commander had to stand with his knees slightly bent, in a semi-squatting position (naturally very tiring) to see out of the cupola. Other complaints included that he had to turn very frequently to communicate to the rest of the crew and he was also charged with loading the coaxial DT machine gun.

The gunner’s position also required improvements. The sight was deemed too far forward and slightly to the left, and the seat required more adjustment. The footrests and pedals required work as well. The knee would be bent too much. Additionally, the heel rest was too far down, requiring the gunner to keep his heel in the air in order to maintain his toes on the pedal, or overextend his ankle, both very tedious tasks.

The loader, aside from the aforementioned loading problems, would have his workspace cramped up by the commander’s seat, only 6-8 ammunition cases were easily accessible, and the machine gun drums were in the way when lifting rounds from the left turret wall.

T-150 after trials, February 1941. The background was manually ‘erased’.
Source: Warspot

Testing of the T-150 was concluded on 14 February. The trial results were reported back to the GABTU and People’s Commissariat of Heavy Engineering. Although the aforementioned issues were noted (and such problems were understandable for a prototype vehicle), it was decided to move forwards with the T-150 project, but in an altered form. Based on reports during this time, both the T-150 and T-220 were sometimes called KV-3. The more common use of this name came with the Object 222 and later with the Object 223, the KV-3 commonly known today.

On 21 February, a commission was made for analyzing the reason for the failure of Plant No.75’s engines on both the T-150 and T-220, and estimating a time of arrival of the fixed engines. The deadline was set for 10 April.

During the same period, between 18 and 24 February, Plant No.75 tested the V-5 engine on KV tank U-21, and it broke down once again, after 40 hours of operation.

On 1 March, the T-150 was officially canceled. The V-5 engine was still unrefined, and the tank was deemed to have several issues necessary to fix, but there was no point in doing so. Instead focus was shifted to the Object 222, which was based on the T-150.

Object 222

Many of the issues of the T-150 that were discovered during the factory trials were identified far earlier on. As a result, the SKB-2’s design bureau started work on a new tank in January-February, 1941 to fix these issues. The new tank, which used the same hull as the T-150, would be indexed Object 222. Originally, the differences between it and its predecessor consisted of a new cooling system and a new turret. This new turret was slightly larger, had flat sides (as opposed to 15° angled inwards on the KV-1 and T-150), and a slightly sloped frontal plate. The commander and his cupola were moved to the back of the turret as well.

By the end of February, the People’s Commissariat of Defence and the Central Committee of the Communist Party proposed accepting the KV-3 (Object 222) into service. Additionally, the topic of improving the main armament to the 76.2 mm F-34 was also raised. This gun had improved ballistics over the previous F-32 on the T-150. As for the propulsion, the tank was to use the same V-5 engine.

On 3 March 1941, a commission was formed, consisting of Military Engineers 2nd Rank I.A. Burtsev and I.A. Shpitanov, Military Engineer 3rd Rank Kaulin, LKZ Director I.M. Zaltsman, SKB-2 Director J.Y. Kotin, Director of LKZ 1st Dept. A.Y. Lantsberg, and NII-48 research institute engineers V. Dalle and A.P. Goryachev. Together, they reviewed the drawings and a full-scale wooden mock-up turret of the Object 222 turret mounted on a KV-1 (for simplicity’s sake). Turret armor would have been 90 mm all around and 40 mm on top. Several issues were identified, such as the flat turret walls, which were deemed to decrease protection, the less than ideal commander position, and the lack of hatch on the cupola for the commander. Despite these issues, the commission concluded that the turret should be built anyways, since there was little time to redesign it.

On March 15, the Council of People’s Commissars of the Soviet Union and the Central Committee of the Communist Party gave decree No. 548-232§, which imposed that LKZ had to switch mass production to the KV-3 (Object 222) in June.

The officials were confident that, by then, the new turret could be tested and refined. As for the T-150’s hull, with the new cooling system and properly tuned V-5 engine, it would run smoothly, as it was essentially just an up-armored KV-1 hull.

Object 222 drawings, circa March 1941. The tank was named KV-3 and was supposed to enter service in June, but the situation changed shortly after. It used the hull of the T-150.
Source: Yuri Pasholok

German Heavy Tanks

However, 4 days earlier, on 11 March, the Soviet Intelligence services had just released a report regarding the German Reich’s tank developments. Notes of several heavy tanks were highlighted, notably three new tanks that were under development. One of them was labeled Mark V, was to weigh 36 tonnes, and be armed with a 75 mm gun. The Mark VI was to weigh 45 tonnes and be armed with a 75 mm gun, and, finally, the Mark VII was to weigh 90 tonnes and be armed with a 105 mm. The first 2 tanks can be confidently identified now as the VK.30.01(H) and VK.36.01(H) and early Tiger mentions. But the latter can only be described as some early proposal to what would become the Pz.Kpfw.VII Löwe, which was first mentioned officially in German documents in November 1941.

This new German heavy tank was nearly double in weight of the KV-3 and considerably above the T-220. The 105 mm gun was far more alarming than the 76.2 mm F-34 that the KV-3 (Object 222) was to be equipped with and the 85 mm F-30 on the T-220.

On 21 March, the GABTU requested the urgent development of a new heavy tank from SKB-2 at LKZ, capable of matching the supposed German heavy tanks. It was to weigh up to 72 tonnes, have 130 mm of frontal armor, and be armed with the 107 mm ZiS-6 gun. It was indexed Object 224 / KV-4. On April 7, the GABTU would rework their approach, requesting that the KV-3 be based on the T-220 (Object 220) and armed with a 107 mm ZiS-6 and weigh 68 tonnes. The new KV-3 was indexed Object 223. An even heavier tank was also conceived, the KV-5 (Object 225), with 170 mm of frontal armor and 150 mm of side and rear armor, weighing over 100 tonnes.

The ‘later’ KV-3 (Object 223) with the 107 mm ZiS-6 gun. Development would start in April, based on the Object 221, and would continue until December 1941.
Source: Warspot

After the invasion of the Soviet Union and the Siege of Leningrad in September, much of the SKB-2’s design bureau and its prototype tanks were evacuated to the ChTZ plant in Chelyabinsk, which was now renamed ChKZ, or Tankograd.

Most of the work on the heavy tanks was stopped in order to focus on more sensible topics at ChKZ. The only exception was the Object 222 (which had now been renamed to KV-6) and the Object 223 (KV-3). The GABTU was against the KV-6 and insisted on improving the armor of the T-150 to 120 mm and adding a new ZiS-5 gun. These were the last efforts on these tanks. The Object 223 (KV-3) progressed until December 1941.

These experimental tanks were incredibly expensive. A letter sent on 30 May 1941 to Military Engineer 1st Rank Korobov by A.Y. Lantsberg described the development costs of the major KV series of heavy tanks (Object 150, Object 220, Object 221, Object 212, Object 218, Object 223, Object 224, and Object 225). These had a total development sum of 5,350,000 rubles. The T-150 project would cost in total 1,500,000 rubles. In perspective, a KV-1 in 1941 would cost between 523,000 to 635,000 rubles.

Stage of T-150 Development	Price (thousands of rubles)
Draft drawings	50
Technical drawings	50
Prototype construction and factory trials	900
Proving ground trials	100
Drawing correction after trials	25
Repair of prototypes and improvements	375
Total cost	1500

Source: CAMO RF 38-11355-101

One of the more sensible alternatives was the KV-1E (the E is a post-war addition and derives from the Russian word meaning shield or screens), a regular production KV-1 with 30 mm to 25 mm additional armor plates, making the protection of the KV-1E superior to that of the T-150. The idea of the KV-1 with appliqué armor appeared on 19 June, 1941 and would be given to troops by July.

KV-1 with appliqué armor knocked out. The additional armor on the side of the hull and turret can be seen.
Source: World War photos

Second trials

The work on Object 222, Object 223, Object 224, and Object 225 tanks did not mark the end of the T-150 prototype’s career. During the month of June 1941, the T-150 was retested with a worked-out V-5 engine and improved cooling system. This time, it traveled 2,237 km by 19 June. In total, 5 different V-5 engines had been installed on the tank during its trials. Amongst the issues noted were:

Oil leaks from the gearbox’s primary oil retainer.
Teeth from the 3rd and 4th gear as well as conical gear were sheared off.
Collar bracket of the 2nd and 4th gears were worn out by 4 mm.
2 rubber shock absorbers had been destroyed.
Paper fuel filters failed

Several new production methods had also worked well, such as hot-pressing the torsion bar with the torsion arm together, and the gearbox casing, made out of recycled aluminium, did not show sign of damage or failures after 1671 km.

T-150 in Combat

As the Soviet Union was suffering rapid defeats against the Axis powers, prototype tanks were pressed into service. The T-150 would be no exception. It entered service with the 123rd Tank Brigade on 11 October 1941. A week later, on 18 October, the brigade, part of the 8th Army, fought around Neva Dubrovka and later crossed the Neva river. On 18 May 1943, the T-150, by then part of the 31st Guards Heavy Tank Regiment, was listed as knocked out beyond repair. But the need for tanks was there and it was sent to Plant No.371 for repairs and entered service with the same regiment in July. The commander was Guards Junior Lieutenant I.A. Kuksin and driver-mechanic was Technician-Lieutenant M.I. Shinalsky and the tank received the number 220 and callsign “Som” (Catfish).

Shortly after, Kuksin’s tank would partake in the Mga Offensive or Third Battle of Lake Ladova, and on 22 July 1943, the 31st Guards Heavy Tank Regiment, alongside 63rd Guards Rifle Division, engaged enemy forces south-east of Leningrad. During the fighting between July 22 and August 6, the 31st Guards Heavy Tank Regiment recorded kills of 10 enemy tanks (allegedly 5 Tiger tanks, 3 Panzer IVs, and 2 Panzer IIIs), 10 pillboxes, 34 foxholes, and 750 enemy personnel. Kuksin’s T-150 and his crew also performed well. During this period, they recorded the destruction of 5 foxholes, 2 light machine gun posts destroyed, and 36 soldiers. Their tank was also hit in the track and immobilized, yet the crew managed to get the track together and continue fighting. The tank held its position for 4 days, for which Kuksin and his crew received the Order of the Red Star.

KV-1 with number 207 during maintenance and another KV conducting track repair. According to Yuri Pasholok, these belonged to the 31st Guards Heavy Tank Regiment and the photo was taken in late July 1943. The tank with the track being repaired is claimed to be the T-150 itself.
Source: Warspot

On 12 August, the Regiment was assigned, with the 73rd Marine Rifle brigade, to capture the village of Anenskoye. The 1st and 4th companies attacked on 18 August at 04:55. The companies suffered heavy losses and, by 06:00, 9 out of the 10 tanks were taken out of battle, with only tank 206 being in working order. Amongst these casulties suffered on that day, the T-150 was one of them. Junior Lieutenant I.A. Kuksin, gunner Senior Sergeant A.S. Yurdin, driver Technician-Lieutenant M.I. Shinalsky, and loader Guards Seargant I.M. Brezhak were killed in action on 18 August and the T-150 was sent back to Plant No.371 for repairs.

Commander of the T-150, Junior Lieutenant I.A. Kuksin (left) and Guards Seargant I.M. Brezhak (right).
Source: Yuri Pasholok

Alternatively, a document dated 18 November 1943 shows that a new driver was assigned to the T-150 (noted as KV No.T-150, raising the question as to if the T-150 was ever given number “220”), and was still commanded by Kuksin.

It is worth highlighting that the T-220 also saw combat service, but its new turret and 85 mm F-30 gun were replaced with a regular KV-1 turret. The tank was knocked out during the defense of Leningrad.

Conclusion

The T-150 (KV-150 / Object 150) was, on paper, a minor upgrade to the KV-1, with just 15 mm of additional frontal armor, a more powerful 700 hp engine, and a new commander’s cupola. While the implementation of these changes proved problematic at first, the T-150 proved to be a very important step towards the design of even larger and heavier KV tanks. These ultimately proved to be a waste of money, time, and resources, assets which the Soviet tank industry did not have, especially with the Axis invasion. Like many Soviet pre-war prototypes and its larger brother, the T-220, the T-150 prototype saw combat service well into 1943, but what happened after is unknown.

T-150. Illustration by Pavel Alexe.

Object 222. Illustration by Pavel Alexe.

T-150 / KV-150 / Object 150 Specifications
Dimensions (L-W-H) (approx.)	6.76 x 3.33 x 3.01 m
Total weight, battle-ready	50.16 tonnes
Crew	5 (Commander, gunner, loader, driver, radio operator)
Propulsion	V-5 12-cylinder diesel, outputting 700 hp.
Speed	35 km/h
Suspension	Torsion bar, 6
Armament	76.2 mm F-32 3x 7.62 mm DT machine guns
Armor	Front/sides/rear of hull and turret: 90 mm Top/Belly: 30 to 40 mm
No. Built	1 prototype built and saw service

Sources

Breakthrough tank KV – Maxim Kolomiets
Supertanki Stalina IS-7 – Maxim Kolomiets
KV 1939-1941 – Maxim Kolomiets
Victory Tank KV Vol.1 & 2 – Maxim Kolomiets
Tanks in the Winter War 1939-1940 – Maxim Kolomiets
Constructors of Combat Vehicles – N.S. Popov
Domestic Armored Vehicles 1941-1945 – A.G. Solyakin
Bronevoy Schit Stalina. Istoriya Sovetskogo Tanka (1937-1943) – M. Svirin
About the forgotten creators of Soviet armored power. (historyntagil.ru) – S.I. Pudovkin
Yuriy Pasholok. HF Small Upgrade – Alternate History (alternathistory.com) – Yuri Pasholok
Малая модернизация КВ | Warspot.ru – Yuri Pasholok
КВ-3: набор танковой массы | Warspot.ru – Yuri Pasholok
Опытный танк с боевой биографией | Warspot.ru – Yuri Pasholok
Tank Archives: KV’s Replacements – Peter Samsonov
Tank Archives: Heavy Trials – Peter Samsonov
Tank Archives: Heavy Tank Costs – Peter Samsonov
Tank Archives: T-150 Revival – Peter Samsonov
Tank Archives: Tank Plans for 1941 – Peter Samsonov
Tank Archives: Mass Breakdown – Peter Samsonov
Tank Archives: F-32 Technical Passport – Peter Samsonov
Tank Archives: Kirov Experiments, June 1941 – Peter Samsonov
How much cheaper than German tanks actually cost – Russian Seven (russian7.ru) – Kirill Shishkin
Heavyweight tanks KV-3, KV-4, KV-5 (famhist.ru)
https://sovetarmy.forum2x2.ru/t745-topic

WW2 Soviet KV-4

KV-4 (Object 224) Marishkin

Post author By Pavel Alexe
Post date February 22, 2023
No Comments on KV-4 (Object 224) Marishkin

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–

KV-4 designs

Placement	Name	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
4	Ermolaev KV-4	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

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)

WW2 Soviet KV-4

KV-4 (Object 224) Sychev

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–

KV-4 designs

Placement	Name	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
4	Ermolaev KV-4	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 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
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)

WW2 Soviet KV-4

KV-4 (Object 224) Kruchyonyh

Post author By Pavel Alexe
Post date December 14, 2022
No Comments on KV-4 (Object 224) Kruchyonyh

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–-

KV-4 designs

Placement	Name	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
4	Ermolaev KV-4	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

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
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
Constructor of Combat Vehicles – N.Popov
Real heroes don’t die. South Ural Panorama. (up74.ru) – Marat Gainullin
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
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
Soviet heavy tanks 45-65 – 0020.htm (narod2.ru)
Memoirs such memoirs (livejournal.com) -Yuri Pasholok

Cold War Romanian Armor Modern Romanian Armor

T-72 Ural-1 in Romanian Service

Post author By Pavel Alexe
Post date December 12, 2022
9 Comments on T-72 Ural-1 in Romanian Service

T-72 with fish gill sideskirts. Illustration by Pavel Alexe based on work by David Bocquelet.

Socialist Republic of Romania/Romania (1978-2005)
Main Battle Tank – 31 Purchased from USSR

Romania is relatively well-known for its own tank development projects, such as the TR-85-800 and TR-77-580, the latter entering production in 1978. Yet, just the previous year, after increasing pressure for rearmament for the Warsaw Pact members, the Socialist Republic of Romania purchased 31 T-72 Ural-1 tanks, partially to use as an ‘elite’ battle tank, but most importantly, to use for its own tank development program – the TR-125. The T-72 in Romanian service spent most of its time in absolute secrecy. They were first seen in the December 1989 revolution, where even other Romanian tankers thought it was foreign, and allegedly fired upon them. After the Revolution, they would see regular service alongside other tanks. They were retired prematurely in 2005 with great controversy. They have since disappeared, last time being seen in a degraded state in 2014. One T-72 remains in public view at the King Ferdinand National Military Museum in Bucharest.

One of the 5 T-72s at Pitesti during a parade, 2009.
Source: Resboiu

Background

In the mid-1970s, the Socialist Republic of Romania sought to upgrade and modernize its weapons arsenal massively, partly from purchasing vehicles from the USSR, partially from license production of both Eastern and Western products. A new main battle tank (MBT) was a priority. At the time, Romania only had T-34-85 and T-55 tanks in service, as well as its own tank development program, which would result in the TR-77-580, with production starting in 1978.

This rearmament plan was partly triggered by Commander-in-Chief of the Warsaw Pact and Marshal of the Soviet Union Ivan Yakubovsky, who claimed:

“Every military should have its own units equipped with the most modern types of armament and military technology, for the timely training of ranks for new equipment and gathering experience in using and mastering the equipment.”

To put Soviet Marshal I. Yakubovsky’s idea in practice, in April 1977, Romanian Minister of Defence, General-Colonel Ion Coman, at the alleged indication of Secretary General and leader Nicolae Ceaușescu, sent a letter to the Soviet Minister of Defence Marshal of the Soviet Union, D.F. Ustinov, about the purchase of a battalion of new T-72 tanks. The request was approved by Ustinov, and on 30 August, Ion Coman would send a letter to Ceaușescu stating that the order for 31 T-72 Ural-1 tanks was approved by the USSR.

General-Colonel Ion Coman, Minister of Defense between 1976 and 1980. He would be stripped of his military rank and sentenced to 20 years in jail at a trial in 1991 for his actions in the Revolution.
Source: MApN

Between 1978 and 1979, the Socialist Republic of Romania purchased 31 T-72 tanks from the USSR, in a contract worth 150 million Lei ($12.62 million dollars in 1979, around $52 million in 2022). The contract also included maintenance, ammunition, and troop training costs, and a ‘dummy’ tank for training.

The first T-72 tanks were delivered in 1978 to the 1st Tank Regiment “Vlad Țepeș” (Vlad the Impaler). Although they were produced in 1978, the tanks were not brand new, and had been used either in quality tests or exercises, as spent shell casings were found inside, spare parts and auxiliary tools were used, as well as there being a handful of kilometers on the board. In addition to the 31 functional tanks, Romania also acquired a simulation and training vehicle (no armor and static) as well as extra turrets (used for the TR-125 development).

T-72 Ural-1

In the late 1960s, Factory No.183, Uralvagonzavod (UVZ) would develop its own T-64 upgrade out of its own initiative. The main goals were to be cheaper, simpler, and more reliable than the T-64, allowing for easy mass-production, while still using the main advantages of the T-64. It used many turret and hull components of the T-64, as well as the D-81 125 mm gun. It was equipped with a V-45 780 hp engine, requiring a longer hull than that of the T-64. In January 1968, after its completion, it was named Object 172. In 1971, an improved version was made, using the lower hull and running gear from the Object 167, becoming the Object 172M.

It entered service in 1974 with great controversy. Many saw it as a waste of resources. For example, UVZ factory director I.F. Krutyakov put it as a “tactical mistake”. But the need of replacing the T-55 with a new MBT was growing, and the T-72 would end up being produced at 4 factories and becoming one of the most influential, mass-produced, and iconic MBTs of the Cold War, with countless variants, exports, and uses in combat.

The T-72 featured an 125 mm 2A26M gun with a 22 round carousel autoloading system (an extra 17 rounds were stored outside the carousel), needing just 3 crewmembers, commander, gunner, and driver. Secondary armament consisted of a 7.62 mm PKT coaxial machine gun and a 12.7 mm NSVT anti-aircraft machine gun. Armor (for the early variants) consisted of an upper frontal plate angled at 68º with 80+105+20 mm thick plates. The cast rounded turret was 410 mm thick. Later models would employ various types of ERA and add-on armor, as well as many adjustments to plate thickness and materials.

In December 1975, an upgraded variant of the T-72 would enter service as the T-72 Ural-1, developed at UVZ under leadership of V.N. Venediktov. It differed from the base T-72 models with improved armored protection, thermal sleeve on the gun barrel, and an infrared searchlight to the right of the main gun. In total, 5,250 such tanks would be produced between 1976 and 1980.

Romanian T-72 Ural-1 with its ‘gill’ armor still in place, early 2000s.
Source: Lt. Col. I.Trofimov

Operation – the 1st Tank Regiment “Vlad Țepeș”

The city of Târgoviște was arguably one of the best geographical area for a tank regiment, north of the Muntenian plains and south of the Carpathian mountains. The geographical-strategic advantage of the city had been well-known long before, having served as a capital for Wallachia (Valahia/Țara Românească) between 1396 and 1714. At the beginning of the 20th century, there were proposals to move the capital of Romania to Târgoviște, especially since there was only a 80 km distance between it and Bucharest. In 1872, a cannon factory was built there, which would later act as a maintenance center for artillery, known as Arsenalul Armatei (Eng: The Army Arsenal).

On 6 December 1919, after just 2 months of existence at Giurgiu, the first Romanian tank regiment was moved to the Târgoviște garnison. A year later, after a decree by King Ferdinand, the first Romanian Tank Regiment was created, Regimentul Care de Luptă (Eng: The Battle Tank Regiment) taking effect on 1 January 1921, consisting of 2 tank battalions. In the 1930s, the regiment increased to 3 battalions, receiving new Renault R-35 and Škoda R-2 tanks. In 1939, after a second tank regiment was formed, the Târgoviște regiment was renamed to Regimentul 1 Care de Luptă (Eng: Regiment 1 Battle Tanks). During the Second World War, the regiment, under the 1st Armored Division, fought against the Soviets in the liberation of Bessarabia (Basarabia) and Northern Bukovina (Bucovina), as well as the offensive into Odessa and Stalingrad. After the 23 August 1944 switch to the Allied side, the regiment would defend Transylvania and fight into Hungary, Czechoslovakia, and Austria. In 1974, the regiment was renamed 1st Tank Regiment “Vlad Țepeș”.

Renault FT tanks of the Romanian Tank Regiment in Bucharest, 10 May 1925.
Source: Trupele Blindate din Armata Romana 1919-1947

The T-72 Ural-1 tanks were kept under utmost secrecy and incorporated into their own, independent tank battalion, which was isolated from the rest of the regiment, with exercises and training being done separately. Access to the training polygons was prohibited to members of other units, such as other tank, infantry, and artillery units from the base. Access to the tank facilities could only be done by the tank battalion members, who required a special permit. The unit’s members themselves were recruited after several checks to prove their loyalty to the party and trustworthiness.

The T-72 battalion was very well equipped for Romanian standards. The T-72 tanks were housed in a specially built ventilated warehouse, allowing to run the engines inside. Their unit included a specific “tancodrom”, a training area specially designed for various tank exercises and training, railway with loading platform directly in the barracks and tank storage area, firing range, water crossing and fording trench, ammunition depot, and training halls.

The tanks were kept secret until the Revolution of 1989. The tanks had not been shown to the general public or even other tankers since their introduction. Few tank officers ever got the chance to see them. Former commander of the 1st Tank Battalion “Vlad Țepeș” and blogger, Lieutenant-Colonel Ifrim Trofimov, has written a series of blog posts covering his experiences with the tank. He describes seeing the T-72 for the first time, after being a tanker since 1978 on both the T-34-85 and T-55:

“In 1984, when I was at a company commander training course, in Făgăraș, I saw it for the first time.

It was on a trailer, towed by a Tatra truck, covered by a tarpaulin. Even though we were tens of tank officers, many of us being company commanders, we were not allowed to see it, satisfying ourselves with its silhouette, and whatever we could see from under the tarpaulin: tracks, roadwheels and the gun barrel.”

Czechoslovakian TATRA 813 prime mover transporting a T-55AM, early 2000s.
Source: Lars Erik Salo via Pinterest

The T-72 ‘dummy’ rig for maintenance and technical training.
Source: Lt. Col. I.Trofimov

At the beginning of the 1980s, just a few years after the T-72 was purchased, Interarms attempted to purchase 2 such tanks from Romania. Interarms was a company based in London, claiming that they were willing to purchase armament, equipment and ammunition worth $22 million for a state in the Persian Gulf region. Romanian officials realized that the T-72 tanks were the actual target and that they would end up in the US. The contract did not go through.

T-72 at the Revolution – Petty Combat

During the Romanian Revolution, the military was called in to Bucharest by then Minister of Defence Vasile Milea to defend the Communist regime from the anti-regime protesters in the streets. The following regiments were called in:

Bucharest 1st Mechanized Regiment (equipped with TR-85-800s)
Bucharest 20th Tank Regiment
Caracal 68th Tank Regiment (equipped with T-55s)
Târgoviște 1st Tank Regiment (equipped with T-72s)

The Caracal 68th Tank Regiment was in the midst of switching from the T-55 to the TR-85-800 when the Revolution began. The Caracal regiment was called in to Bucharest on 19 December and were to equip wartime munitions. Choosing the T-55 tanks over the TR-85-800s, according to a platoon leader, 50 tanks (64 according to other veterans) drove the nearly 200 km with a speed of “no less than 40 km/h” and with “sparks coming from our tracks”.

Prior to entering Bucharest, Major Marchiș had told the tankers, “Warning. From this moment, there’s death! There’s shots, we don’t know from where, there are terrorists, we can always have surprises!”

The unit moved slowly towards the Palace Plaza, but was ordered to defend the Ghencea ammunition depot, as allegedly tanks captured by the “terrorists” were approaching it and wanted to blow it up. Naturally, the tankers from 68th Tank Brigade were not informed about what troops were already in, or about to enter Bucharest. Unfortunately, as the 68th Tank Regiment spent most of its time in Ghencea, on the outskirts of Bucharest, there are no period photographs of their T-55 tanks.

T-55 of the 20th Tank Regiment at the Palace Plaza, in front of the Central Committee of the Romanian Communist Party, after the military had joined the fight against Ceausescu alongside the population.
Source: Mediafax

According to the historical register of the Târgoviște regiment, it was called in towards Bucharest on December 22 at 20:20, with a tank column ready for march in 10 minutes. Part of the tanks were to be under command of the 1st Army, and part in direct command of the MApN headquarters. On 23 December, the tanks were searching the areas in Bucharest where “terrorist activities” had been performed, at the request of the MApN. When, at the Northern Station (Gara de Nord) the column was attacked and dispersed, the tanks lost communication between each other. Towards the evening, the tanks were ordered towards Ghencea cemetery to “destroy the terrorist group from the cemetery”. Here, 3 tanks opened fire at a house next to the cemetery. An unnamed tank officer, which had previously been at the construction of the Casa Poporului (Ceaușescu’s large palace), had contacted one of the officers from the tank regiment as to why they were firing upon the house and advised them to stop. In an attempt to convince himself and the tankers that there was no danger, the man went to the house, where he discovered on the other side of the street, 3 TAB APCs with several soldiers in firing positions. The 3 TABs were firing upon the same house as the Târgoviște tankers had. He convinced them to stop, as they were at risk of hitting the tanks on the other side. He was hit in the chest by bullets shortly after and taken home by a civilian for care.

As virtually nobody had seen a T-72 in Romania before, including officers, these were thought at first to be the foreign or “terrorist” tanks. News had already spread about Soviet tanks on the eastern border and the threat of Soviet regular forces entering the country. Other false news, both from media and from civilians, about terrorists with unknown tanks appearing out of nowhere came to the tankers.

Two T-72 tanks from the Târgoviște Regiment in central Bucharest on Christmas Eve 1989. Note that the muzzle cover is still on.
Source: Cartula

Thus, the inevitable happened. On the 24 December 1989, in the first tank-on-tank combat of the Romanian Army since the Second World War, a single (or several, considering the amount of shots fired) T-55 from the 68th Tank Regiment opened fire on a T-72, the tank crew likely not recognizing the T-72 tank type. Thankfully, the T-72s were not equipped with live ammunition (of which there was very little, as it was the only unit to operate the 125 mm gun). Consequently, the T-72 crew attempted to drive away. The tank was struck in the engine bay, but the automatic fire extinguisher system prevented any disaster and the crew was able to exit the tank. The action was recalled by retired Deputy Sergeant Marin Oane from the 68th Caracal tank regiment in an interview:

“We fired upon that tank, it was said that it had been captured by the terrorists and came to blow up the (Ghencea) depot. They were actually our colleagues from Târgoviște.”

The tank combat story, according to the Târgoviște regiment historical register, was slightly different. On 24 December, a T-72 was struck by a TR-85-800 from the 1st Mechanized Regiment and 3 other T-72s acted to deter the attack. However, in the detailed memoirs of General Marin Oană (Lieutenant-Colonel of the 1st Mechanized Regiment) about the actions during those days, he does not mention of any contact with tanks from the 1st Tank Regiment.

At an unclear date, the T-72 tank was recovered and sent to Mizil for repairs. At the installations, Ifrim Trofimov was able to get a look at the damage done. In total, 5 (4 according to the unit commander at the time) shots had hit the T-72 (in unknown order):

Shell 1: Likely an HE-FRAG, exploded on impact with the antenna mount, melting the antenna and scraping off the paint.
Shell 2: Also an HE-FRAG, hit the right rear fender, damaging it and bursting an external fuel tank.
Shell 3: Also an HE-FRAG, hit the left side of the rear armor plate, denting it.
Shell 4: A BK-412 AP- HEAT round penetrated the tank, right at the welding between the rear plate and the left sidewall. The cumulative molten jet had penetrated the armor and entered the engine compartment.
Shell 5: Also a BK-412 AP-HEAT, penetrated through the exhaust and into the engine compartment.

One of the most iconic and cinematic pictures of the Romanian revolution. This T-72 has several civilians on its engine deck, sometime between 22 and 25 December 1989.
Source: Ullsten bild – Reuters

Post-1989 & Dissolution

After the Revolution, between 1992 and 1995, the unit was reorganized by the C.S.A.T. (Supreme Council of National Defense). Firstly, the T-72 tanks were no longer a secret, and would be incorporated into a complete tank battalion, with 30 T-72s and 10 T-55AM2s, renamed to the 1st Tank Battalion “Vlad Țepeș”. The new organization, which was applied to all tank units, was as follows: a tank platoon had 4 tanks, a tank company had 13 tanks (4 platoons of 3 tanks each plus a command tank), while a tank battalion had 40 tanks (3 companies of 13 tanks each and one battalion command tank). A single tank battalion was part of a mechanized regiment. The Târgoviște Regiment had an additional 108 tanks, 12 SU-100 SPGs, as well as various APCs, Malyutka-equipped BRDM-2s, and more.

As Romania was preparing to join NATO, the military underwent drastic changes. Many systems and equipment had been retired and subsequently scrapped or sold off. Romania’s military would change its military from a massed conscript force to a professional Western-style army. Concerning the tank forces, this meant that Romania would only have 5 tank battalions.

Signs that the T-72 would be phased out came as early as September 2001, when live-fire training of tankers would be done on TR-77-580, after training on the T-72, which it operated. Worthy to add is how different the 2 tanks were, as the TR-77-580 had a manually loaded 100 mm gun, as opposed to the autoloading 125 mm gun of the T-72.

Structural changes were implemented in June 2002, with the entire regiment being decreased in size and structural and bureaucratic functions removed. During the same period, the new TR-85M1 (upgraded TR-85-800) was supplied, and crews began training on it.

In 2004, the C.S.A.T. officially disbanded the 1st Târgoviște Battalion, ending an 86 year old tank tradition at the Târgoviște garrison. In January 2005, the tanks were transported away on flatbeds, 5 sent to Pitești and the remaining 25 sent to a storage facility in Voluntari, northern Bucharest. From there, they ended up in the yard of the UMB factory (Uzina Mecanica București), where the last picture of them was taken in 2014. They have since disappeared.

Memorial plaque with the names of the commanders of the 1st Tank Battalion “Vlad Tepeș”, 1957-2005.
Source: Lt. Col. Ifim Trofimov

Why the T-72 tanks were taken out of service remains a mystery, with no official answer ever given. Lt. Cl. I. Trofimov, who was assigned battalion commander of the troublesome T-72 battalion in 2001, blames it on the stupidity of higher-ups, an idea slung around far too often both in terms of Romanian military and industry. According to him, in 2005, when the tanks were sent away for storage, they still had 6 spare guns, 21 unused engines, and a host of spare parts. In contrast, according to other sources, the number of usable tanks decreased rapidly in the last few years of service. Allegedly, 28 were functional in 1995. By 1998, it dropped to 15, and in the 2000s, as low as 12. Why they were not repaired with the aforementioned abundance of spare parts remains a mystery, though funding and lack of skilled mechanics on the tank and specific systems could have been an answer.

By joining NATO in 2004, Romania broke its already dwindling relations with Russia, and any hopes of securing further spares, and most importantly, ammunition, were gone. This explains why there were no longer any firing trials with the T-72’s main gun. With little ammunition left, the remaining stocks were saved for potential use in combat, and ultimately, the tanks were no longer worthy of active use and training. Consequently, the tanks were withdrawn from service with the 1st Tank Battalion “Vlad Țepeș”. By the 2010s, 29 (remaining one was sent to the King Ferdinand Military Museum) T-72 tanks were listed up for sale by Romtehnica, the defense trading company of the Romanian Ministry of Defense.

The T-72 at the King Ferdinand National Military Museum in Bucharest. Note the larger TR-125 (P-125 to highlight that it is a prototype) to its right.
Source: Author’s collection

In spring 2022, with the Russian invasion of Ukraine, there were rumors on social media about Romania donating its remaining T-72 tanks to Ukraine. While Romania has shipped over $3 million worth of gear, ammunition, and provisions, heavy equipment, such as unoperational T-72s, have never been considered publicly, although some Romanian-produced TAB-71Ms have appeared in Kherson. If these tanks still exist and were not scrapped or sold by 2022 is up to question.

At least 11 T-72 tanks rotting at UMB Bucharest in 2014. They have since been removed.
Source: Victor Samartinean

114th Tank Battalion “Petru Cercel”

On 1 October 2009, the C.S.A.T. would reinstate armored forces in Târgoviște, with the creation of the 114th Tank Battalion “Petru Cercel”. However, the Battalion would be equipped with 54 aging T-55 and T-55AM/AM2 tanks, essentially replacing a T-72 battalion with a T-55 battalion over a period of 5 years. The Battalion is active to this day.

Detachment of 3 T-55s and a T-55AM during the ARGEDAVA 21 exercise, 2021.
Source: MApN Facebook

TR-125 (P-125)

After the Soviet invasion of Czechoslovakia in 1968 and Ceaușescu’s heavy criticism of it, Romania’s military attempted to decrease its reliance on Soviet weapons imports, and turned towards Western countries for patents and technology. In terms of tanks, this meant the development of the TR-77-580. Based on the Soviet T-55, it saw improvements on paper, but, due to Romania’s lack of experience in the field, had several production and technical issues. Shortly after, in 1986, the TR-85-800 would begin production. Largely based on its predecessor, it saw major improvements, such as an 800 hp engine, reverse engineered from the German Leopard 1.

After Romania purchased the T-72 from the Soviets, it intended to locally produce it as well, just like the Yugoslavs had done with the M-84. A production patent was requested, but it was not granted by the Soviet government. Thus, Romania began reverse engineering the T-72, in what would become the TR-125. The T-72, and in turn the TR-125, were meant as a sort of “elite” battle tank, operating independently and in significantly fewer numbers to the T-55s, TR-77-580s, and TR-85-800s. However, due to the fall of the Communist regime and in turn Cold War, massive military budget cuts and privatization of many enterprises sentenced the TR-125 project to a slow demise. Recognizing that the TR-125 was clearly obsolete as a new MBT by the 90s, in the 2000s,the TR-2000 program was born. Several new tank models would be designed with the help of Krauss-Maffei and their components, while keeping the TR-125 as a basis. The project was too expensive and cancelled. Instead, the TR-85-800 were upgraded to the NATO-standard TR-85M1.

One of the 10 TR-125 prototypes, now exhibited at the King Ferdinand National Military Museum in Bucharest.
Source: Flickr

Type 64

During the many Sino-Romanian armament negotiations, the Chinese were able to learn that Romania had purchased 31 T-72 tanks from the USSR. This move fit the Chinese interests very well, as they had been searching for Soviet T-72s to be able to develop a new generation of MBTs. The Chinese offered fighter jets (likely of Soviet origin) or Harbin H-5 bombers and tank maintenance equipment in exchange of 1 T-72 Ural-1. Whatever the final offer was, the Romanians accepted and the tank was dismantled on Romanian soil, packed into containers and shipped to China. The tank was given the codename Type 64. The vehicle was reassembled without technical instructions in China and tested significantly. With information gathered from it, the Chinese were able to develop a new generation MBT, the Type 96 (Type 96). The vehicle is now somewhere in Inner Mongolia, China.

The Type 64 in more recent years. Note that the ‘gill’ armor and 12.7 mm NSVT machine gun have been removed.
Source: Voodoo_Six_one via WT forums

Conclusion

The T-72 was one of the most iconic MBTs of the Cold War and remains widely used to this day. Romania purchased 31 such tanks from the USSR in the late 1970s and kept them under extreme secrecy until the 1989 Revolution. Since then, the tanks operated normally all throughout the 1990s, until it was decided to remove them from service, arguably prematurely, and send them into storage. The Romanian T-72s were also crucial in the development of Romania’s own tank program, in the form of the TR-125, but also the sale of a single model to China, which renamed it Type 64 and triggered their Second Generation MBT development.

T-72 as seen during the Revolution. Illustration by David Bocquelet.

T-72 with fish gill sideskirts. Illustration by Pavel Alexe based on work by David Bocquelet.

T-72 Ural-1 in Romanian service specifications
Dimensions (L-W-H)	9.53 (incl.gun) – 3.59 – 2.23 m
Total Weight, Battle Ready	41.5 tonnes
Crew	3; commander, gunner, driver
Propulsion	780 hp diesel, V-12 config.
Speed	～60 km/h
Armament	125 mm 2A26M autoloader 7.62 mm PKT machine gun (coaxial) 12.7 mm NSVT machine gun (roof-mounted AA
Armor	UFP angled @ 68 deg. 80+105+20 (mm) Frontal turret: Ca. 410 mm Side turret: Ca. 210 mm Side hull: 80 mm Hull deck: 20 mm Hull belly: 20 mm
Total Purchased	31 purchased + 1 training dummy

Sources

Trupele Blindate din Armata Română 1919-1947 – Cornel I. Scafes, Horia V. Serbanescu, Ioan I. Scafes
Buletinul Arhivelor Militare Române Nr.90 2020 – Petre Opris
tROfi: Despre T 72-ul dâmboviţean (1) (trofi53.blogspot.com) – Cl. (r) Ifrim Trofimov
Organizarea unitatilor de tancuri in Armata Romana – Romania Military (rumaniamilitary.ro) – Cl. (r) Ifrim Trofimov
https://www.rumaniamilitary.ro/realizarea-tancului-tr-125#prettyPhoto Cl. (r) Ifrim Trofimov
rechizitoriu_revolutie_2d8cab0025.pdf (realitatea.net) – (july 2022) Cl. Magistrate Cătălin R. Pițu
“>T-72 “Ural-1” – December 15, 1975 (livejournal.com) – Andrei BT
Object 172M | Tank museum Patriot park Moscow
Amintiri din decembrie ’89: „Dacă n-am încălecat la morţi de m-au găsit loazele, mi-era nu ştiu cum să-i calc cu şenila“ | adevarul.ro – Alina Mitran
Cum a devenit Târgovişte punct nevralgic pe harta militară a Europei. Fabrica de tunuri a lui Cuza şi intervenţia imperativă a Rusiei ţariste | adevarul.ro – Corina Slamnoiu
Amintiri din ’89. Sute de militari au primit alarma „Radu cel Frumos” | Digi24

WW2 Soviet Heavy Tank Prototypes

IS-M (Sashmurin)

IS-M as illustrated by Pavel Alexe, funded by our Patreon campaign.

Soviet Union (1944)
Heavy Tank – Drawings Only

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Just months after the IS-2 began production, work began on developing a new heavy tank to replace it down the line. Engineer N. F. Shashmurin and his team envisioned an unusual tank, meant as a direct IS-2 upgrade, the IS-M. The most notable aspects of Shashmurin’s design were the large-diameter road wheels and the rear mounted turret. However, his project was not taken into consideration and was short-lived, although it did pave the way to the IS-6, which used some of its features.

The IS-M model as represented in Wargaming’s game World of Tanks
Source: World of Tanks

Shashmurin and the IS

Tank designers are usually overlooked in the popular imagination, and those few acknowledged are usually limited to the likes of Ferdinand Porsche or Alexander A. Morozov. Even when limited to Soviet heavy tanks, the names of Nikolai L. Dukhov and Joseph Y. Kotin overshadow the others. Yet Nikolai Fedorovich Shashmurin was the man behind the creation of one of the USSR’s greatest war-winning tanks, the IS-2.

Born in 1910 in what at the time was called St. Petersburg (to be renamed Leningrad in 1924), Nikolai Fedorovich Shashmurin started his engineering studies at the Leningrad Polytechnic Institute in 1930 and graduated in 1936. By 1937, he had started to work at LKZ (Leningrad Kirov Plant) as an engineer for the SKB-2 design bureau. Before the war, he would work on the T-28 medium tank and create the torsion bar suspension system (T-28 No.1552) fitted on the SMK and U-0 (first KV-1 prototype), a system which would be implemented further on all future Soviet heavy tanks and self-propelled guns. Additionally, he developed gearboxes for the KV-1 (his gearbox would be dropped in favor of Dukhov’s infamous gearbox which would haunt the KV-1 for its entire service life), KV-220, KV-3, and even his own design for the KV-4 program.

N.F. Shashmurin in the 1930s.
Source: Bronetechnikamira.ru

With the beginning of the German siege of Leningrad in 1941, the LKZ (Leningrad Kirov Factory), specifically SKB-2 engineers, were evacuated to ChTZ (Chelyabinsk Tractor Plant) in Chelyabinsk (near the Ural Mountains), renamed ChKZ (Chelyabinsk Kirov Plant) a few weeks later. At Chelyabinsk, Shashmurin would develop the gearbox of the KV-1S and, after N. V. Tseits’ death in summer 1942, he became the head engineer for the KV-13 (at the time called IS-1), a vehicle which he did not like. Nonetheless, he would build upon it, and by May 1943, he had designed a new variant, equipped with an 85 mm D-5T gun specifically for the task of penetrating the German Tiger I, mated to a new hull. This was the Object 237 (at the time named IS-3), which would be adopted in service in September 1943 as the IS.

In parallel, Shashmurin designed the Object 238, meant to fit the new 85 mm S-31 gun in the KV-1S, but it was unsuccessful due to the cramped conditions within the turret. Production of the IS-1 started in November of that year, but it would not last long, as, by May 1943, work began on fitting the IS with the 122 mm D-25T gun, and by December 1943, the Object 240 would enter service as the IS-2. The mounting of such a powerful high-caliber gun was unprecedented in Soviet heavy tanks, which normally had similar, if not the same, guns as medium tanks.

Improving the IS-2

Extensive testing of the IS-2 was done at the NIBT (38th Research Test Institute of Armored Vehicle) proving grounds at Kubinka in January and February 1944, where it was concluded that the armor of the tank was not sufficient. Most notably, the “stepped” frontal hull was considered a weak spot, and it was proposed that the frontal hull should be made out of one angled plate.

IS-2 during testing at NIBT, January/February 1944. Note the 122 mm D-25T gun with the German-style muzzle brake.
Source: Warspot

The NiBT proving grounds’ proposal to change the shape of the frontal armor of the IS. Note the old shape in the non-continuous line.
Source: Yuri Pasholok

IS-2 with sloped frontal plate, as originally proposed by NiBT proving grounds and Shashmurin in 1944. The sloping is similar to that on the IS-M.

Even after the first IS combat engagements, it became clear that, with the introduction of the German Panther tank, armed with a 75 mm KwK 42 L/70 (which could pierce the frontal armor of the IS heavy tanks) that the IS was insufficient. As early as September 1943, General Fedorenko (Head of the Armored Vehicle Directorate of the Red Army) would send a letter to Stalin, requesting the thickening of the IS armor and increasing its weight to 55-60 tonnes.

Additionally, in November 1943, the technical requirements for a new heavy tank were set by the GABTU (Main Directorate of Armored Forces). It was to have a mass of 55 tonnes, crew of 5, 160-200 mm of armor(frontal turret and hull), 800-1,000 hp engine, and a 122 or 152 mm gun. Speed was to be at least 35 km/h. These requirements would be laid down at the ChKZ plant on 3 December (10 December according to other sources) by factory director I.M. Saltzman.

The ChKZ SKB-2 design bureau, headed by N.L. Dukhov, had already worked on a new heavy tank since July, with its own funds. It was the 56-tonne K tank. The project was named Object 701.

However, on 21 March 1944, the GABTU changed the technical requirements. The weight was lowered to 55-56 tonnes, armament was a 122 mm gun with a muzzle velocity of 1,000 m/s, and 30 to 40 rounds had to be carried. The engine was to have a 1,000 hp output and allow for 40 km/h top speed. Armor thickness was not specified, instead, it was to be immune frontally to the Panther’s 75 mm KwK 42 L/70 and the 88 mm PaK 43/2 L/71 of the Ferdinand/Elefant.

These changes forced the reworking of the existing Object 701, but a green light was given the same month to produce 2 prototypes, leading to the IS-4 tank’s long development, with the first prototype, the Object 701-0, being built in May 1944.

The Object 701-0, the first prototype of what would become the IS-4.
Source: Supertanki Stalina IS-7

At the same time as the developments at SKB-2, the other design institution at ChKZ, Factory No.100, also worked on their own tanks based on the same requirements. Headed by J.Y. Kotin, their approach was different to that of SKB-2. Instead of designing a new tank, they focused on a deep modernization based on the IS-2. By 18 April 1944, Factory No.100 would present its initial designs. Again, 2 models were built, one with a frontal plate separated into 3 parts (as on the first K tank) and one with a UFO-shaped hull, akin to the Object 279, designed and built decades later. Despite the increased protection, both variants had the same weight as the IS-2, 46 tonnes.

Factory No.100 April design of an upgraded IS-2. Note the UFO-shape hull and large road wheels.
Source: Supertanki Stalina IS-7

The 2 models designed by Factory No.100 on either side of an IS-2 tank model.
Source: Warspot

A document dated 8 April 1944, ordered J.Y. Kotin and his team to develop an upgraded variant of the IS-2 and subsequent SPGs over a 3-month period. The improvements should have included, but not been limited to, strengthened the armor protection, transmission, and chassis.

This would likely trigger the development of a new IS-2 modernisation, based on the requirements from 21 March. The design was to be less ‘radical’ and closer to the IS-2, but some very big changes were made. The tank would be called the breakthrough tank IS-M, the M standing for модернизация, meaning ‘modernisation’.

Sources do not agree exactly when development started, some arguing March, whereas others early April 1944. Nonetheless, N.F. Shashmurin was head of the project. While some design elements were taken from the previous upgraded designs, the main change was moving the turret to the rear of the hull, creating a very unique tank. A drawing of the tank would be made by Dobrovolsky. Who he was is so far unknown.

Design

The design of the IS-M was peculiar and unorthodox. The entire upper hull was made from several stamped steel plates, slightly angled inwards, with both the front and rear angled heavily. These were welded to the lower hull, which, while still mostly flat, had angled corners for extra weight saving. In addition to the main variant, a second variant was drawn out, with standard IS running gear. An SPG version was drawn as well, although only with very superficial details.

The IS-style turret was mounted at the rear of the hull, which allowed for very little gun overhang, decreasing the chance of the gun getting damaged in tight places such as forests and cities, or steep maneuvers, such as trenchcrossing. Despite its general shape being similar to the turret of the IS, several key components had been done away with, such as the big commander cupola or air vent.

Original drawing of the IS-M from an old magazine. The caption said “Breakthrough tank IS-M”. Note the SPG in the background, explained below.
Source: Warspot

Powerplant

The engine was to be an M-40 aviation engine, equipped with 4 TK-88 turbochargers. The displacement was of 61.07 l and had an output of 1,200 hp. Other sources claim it was a modified variant of the standard V-2-IS, such as the V-11 or V-16, yet these would only output between 500 and 700 hp, far less than the 800 to 1,000 hp specified. The M-40 engine was based on an aviation engine, thus could run on both diesel and kerosene. Whatever the engine was, it had a 10 h running time. The powerplant was kept inside an own compartment in the center of the hull, protecting the fighting compartiment and ammunition, consequently isolating the driver. Fuel tank was in the front, to the right of the driver. As the sprocket remained to the rear of the hull, the entire braking and final drive ensemble was kept at the rear, as on the original IS. However, this meant that the gearbox and driveshaft ran through the floor of the crew compartment. The transmission was likely offered in 2 variations, electromechanical, very similar to that on the Ferdinand/Elefant, or a conventional mechanical one. The gearbox was of planetary type.

For access to these components, the rear engine plate could be opened and rested on the hinges, for access to the final drive and brakes. The roof of the engine compartment was also removable, and had one engine access hatch, 4 air vents and 4 air purification filters.

Suspension

Two different running gear options were presented, one with 6 large-diameter road wheels, which allowed the returning track to rest on them, or 6 IS road wheels with 3 return rollers. The large road wheels would offer improved mobility over very muddy terrain, where smaller road wheels would clog up with mud. Additionally, they removed the need for return rollers. In turn, the standard IS wheel layout was already in use on various IS and KV series of tanks, resulting in a cheaper and smarter logistic choice. In both variations, the wheels were sprung by torsion bars.

Crew

The crew was larger than on the IS-2, with 5 men; a commander, gunner, loader, driver, and radio operator. The commander sat in the left corner of the turret. He had a low profile cupola equipped with 2 opposite facing periscopes for vision. Sat in front of him was the gunner, who operated the main gun. He had the main gun sight for vision and an extra, fully rotating periscope for a better field of view. Opposite him, to the right of the gun, sat the loader. He had to load the 2-part ammunition gun, as well as assist the commander in various tasks. For entry and exit, he had his own hatch with a periscope. The driver sat in the front of the hull, from where he would control the tank with 2 tillers. One direct vision slit in the armor was provided, as well as a fully rotating periscope. For ease of driving during the night and visibility during maneuvers, the tank had a single headlamp on the right side of the upper hull. The radio operator was likely seated to the driver’s right, also in the hull. He also had a rotating periscope for vision.

Armament

The exact armament of the IS-M was never specified, other than its caliber, 122 mm. However, considering the German-style muzzle brake, it was a D-25T, as on the standard IS-2. The tank was equipped with 40 shells for the main gun.

122 mm D-25T ammunition specifications
Shell type	APHE (BR-471)	APHE (BR-471B)	HE (OF-471)
Mass (kg)	25	25	25
Muzzle velocity (m/s)	795	795	800
Explosive	160 g	160 g	3.6 kg TNT
Penetration	200 mm	207 mm	42 mm (calculated)

Around the tank, 3 GVG 7.62 mm machine guns were mounted, one coaxial to the main gun, one in a ball-mount at the rear of the turret, and one in the frontal hull, which is not visible in the drawings. A ‘large caliber’ machine gun was to be added to the commander’s cupola for anti-aircraft purposes, likely a DhSK 12.7 mm machine gun, but it is not shown in the drawings either.

The SPG variant of the IS-M was likely armed with an 152.4 mm BL-8 gun, developed at the beginning of 1944 and tested during July of the same year on the ISU-152-1 (Object 246).

152 mm BL-8 ammunition specifications
Shell type	APHE (BR-540)	APHE (BR-540B)	HE (OF-540)
Mass (kg)	48.8	48.96	43.56
Muzzle velocity (m/s)	850	850	850
Explosive	0.66 g	480 g	5.86 kg TNT
Penetration	247 mm	276 mm

ISU-152-1 (Object 246) armed with the 152 mm BL-8 gun.
Source: Wikimedia

Armor

The frontal plate was a continuous flat plate of 200 mm angled at around 45°. Side armor was 160 mm thick and angled at 60° on the upper hull and flat on the lower hull. The rear was also heavily angled and 120 mm thick. The turret was 160 mm all around, but being awkwardly rounded, it increased its effectiveness significantly frontally. This gave the IS-M superior protection to any heavy tank of the time, while still maintaining a modest 55 tonnes weight.

Frontal cutout view of the IS-M highlighting the hull armor and engine placement.
Source: Screenshot from original drawing

Variants

In the background of the original drawing, 2 additional vehicles can be seen. The first is also an IS-M, but with a different set of running gear, namely 6 IS-style road wheels and 3 smaller return rollers. This was likely added as an alternative to the large roadwheel design.

Full drawing of the IS-M variant with standard IS road wheels and return rollers.
Source: Screenshot from original drawing

Further back, a completely different vehicle is shown, a form of SPG based on the IS-M. The turret was replaced with a fixed casemate with a large 152 mm BL-8 gun. Interestingly, the running gear is the same as on the previously described IS-M.

View of the IS-M based SPG. Note the much larger muzzle brake, characteristic of the BL-8.
Source: Screenshot from original drawing

Return to Leningrad and Further Developments

The IS-M was short-lived. Alongside its 2 earlier counterparts, all were abandoned in April 1944. Instead, Factory No.100 began work on a vehicle meant to rival the SKB-2’s Object 701 and thus become the new generation heavy tank. It would incorporate several features from both the IS-M and the 2 wooden mock-ups presented on 18 April 1944. This was the IS-6, designed at first in secrecy. Like on the IS-M, 2 variants were designed, one with large diameter road wheels and a steeply armored hull (Object 252). The second would use an electromechanical transmission on an IS-2 lower hull (Object 253).

In May, with the Soviets having lifted the Siege of Leningrad, the SKB-2 design bureau and Factory No.100 were moved back, and thus the LKZ was revamped. Many engineers moved back, including Shashmurin. Back in Leningrad, they would continue work on the IS-6. In August 1944, the Object 244 was used as a testbed for the Object 252’s wheels, first designed on the IS-M, and later the 122 mm D-30 gun. The Object 244 itself was a prototype dating back to February 1944, meant to test the new 85 mm D-5T-85BM on an unmodified IS-1 (Object 237). The project was named IS-3, although this has nothing to do with the later IS-3 heavy tank (Object 703). After a military representative from Factory No.100 reported the IS-6 secret development to the GABTU, it was ordered that further development and prototype production should take place at Uralmashzavod in Yekaterinburg, but without the end game of entering production.

The modified Object 244 with 5 of the large-diameter road wheels and the 122 mm D-30 gun. Note the original IS road wheel in front of the sprocket.
Source: thedailybounce

Cutout drawings of the large-diameter roadwheel of the IS-6 (Object 252). They were originally designed for the IS-M.
Source: Warspot

The Object 252 IS-6 prototype during testing in November/December 1944. Despite being promising, its protection was deemed insufficient.
Source: Topwar

Back at ChKZ, which had been working full-time on the Object 701, it was realized that it needed to present its own modernization of the IS-2. Thus, in August 1944, they presented the blueprints of an upgrade to the IS-2. At first glance, it looked like an unchanged IS-2, but it featured various improvements, such as refined frontal armor layout, thicker turret armor, improved turret design, and many mechanical changes, such as improved cooling system and engine room. Allegedly, one prototype was built. Yet, by October 1944, the project was abandoned in favor of a new tank, which incorporated many IS-2 features, but was still radically new. It was called the Kirovets-1 and given the Object 703 index. After several alterations, most notably the addition of its most famous feature, the legendary pike-nose, the IS-3 was born.

The Kirovets-1 (not to be confused with the K-tanks), winter 1944.
Source: Warspot

The pike-nose on the IS-3 was ‘borrowed’ from the IS-2U and Object 252U, an upgrade of the IS-2 and Object 252 meant to equip them with pike-noses. As a matter of fact, the IS-2U, designed in November 1944, was the last genuine attempt to fundamentally upgrade the IS-2 heavy tank. The IS-2 U’s turret was itself heavily inspired by earlier designs, such as the IS-M.

The IS-2U designed at Factory No.100, was essentially an IS-2 with a new turret and frontal hull. It was the last significant attempt to modernize the IS-2.
Source: ofis7andthings

The IS-6 would end up unsatisfactory. The GABTU never intended to adopt it into service regardless. The Object 253 with the electromechanical transmission caught fire during testing. Both IS-6s were deemed insufficiently armored in comparison to the IS-4, and once the IS-3 was nearing production, the fate of the IS-6 was sealed.

Shashmurin himself, who had worked throughout the entire development of the IS-6, was never fond of the idea. Just like on the KV-13, he was a true believer in what he called “tank of maximum parameters” a tank which pushed the capabilities of the industry and designers to their limit, in an attempt to reach an unstoppable heavy tank. His first such vehicle was the IS-1 and later IS-2. For him, the IS-6 was a waste of time, especially considering the end of the war. As for the rivaling ChKZ heavy tanks, he had the following to say:

“We had finally created an almost perfect tank, capable of breaking through any enemy defenses. Ideal in its potential, all the qualities of the IS-2 could manifest themselves only in the development of the solutions found and tested in it. Alas, the improvement of the IS-2 was left to chance, and instead of developing already tested solutions, they began to invent new “bicycles”. An unjustified race began in the creation of independent models of heavy tanks, in many respects similar to the race that took place when creating the KV. The sad experience of the very recent past had taught us nothing…
The impressive, but unreliable IS-4 and IS-3 were being designed and created, another “monster” with two engines was being designed, a kind of electric locomotive was being built on tracks – a tank with an electromechanical transmission IS-6, which burned down after driving through the factory yard only 50 meters. In general, the design idea was in full swing, and in the meantime, the fighting was done by the “rude” workers of the IS-2, and not by the “handsome” IS-3, the production of which began in the early ‘45 and which immediately began to break down with the regularity of the sad memory of the KV-1.”

—N.F. Shashmurin, extract from Soviet Warrior magazine, interview by Sergey Ptichkin

After the war, Shashmurin would finally fulfill his dream of designing a true “tank of maximum parameters”, the IS-7, which indeed, pushed the technology of the time to its limits, being the heaviest Soviet tank ever built, as well as several work on ATGM-based heavy tanks, PT-76 and more.

Conclusion

The IS-M itself was a short-lived design meant to offer an arguably unnecessary upgrade to the IS-2. It would incorporate some very interesting features and solutions, such as a rear mounted turret, large diameter road wheels, and a curved hull. It alo took in consideration several running gear designs and an SPG layout. Nonetheless, despite its short life, it was a crucial factor in the developmental progress of Soviet heavy tanks during the Second World War, by leading directly into the development of the IS-6, which lost in turn to the more refined, though still crude, IS-3 and IS-4 designed at ChKZ. For Shashmurin, the IS-M was certainly not his most prideful creation, but through its odd nature, it complements well the career of one of the USSR’s most important heavy tank designers of the Second World War.

IS-M as illustrated by Pavel Alexe, funded by our Patreon campaign.

IS-M variant with standard IS road wheels and return rollers as illustrated by Pavel Alexe, funded by our Patreon campaign.

IS-M based SPG as illustrated by Pavel Alexe, funded by our Patreon campaign.

IS-M specifications
Dimensions (L-W-H)	7 x 3.2 x 2.7 (m)/td>
Total Weight, Battle Ready	55 tonness
Crew	5
Propulsion	1,200 hp diesel (V12) M-40 with 4 turbochargers or 500-700 V series engines
Speed	40 km/h
Armament	122 mm D-25T 3x GVG machine guns 1 (?) DhSK machine gun
Armor	Turret: 160 mm (hull) front: 200 mm Sides: 160 mm Rear: 120 mm Roof and belly: 30 mm
Total Production	0, drawings only

Sources:

IS Tanks – Igor Zheltov, Alexander Sergeev, Ivan Pavlov, Mikhail Pavlov
Supertanki Stalina IS-7 – Maxim Kolomiets
Heavy Tank IS-4 – Maxim Kolomiets
Tank Power of the USSR – M. N. Svirin
Modest genius: who created the IS-2 tank, which became a symbol of Victory – Rossiyskaya Gazeta (rg.ru) – Sergey Ptichkin
Holes in the armor -Sergey Ptichkin, Sergey Zykov
Tank Archives: Modernization on Paper – Yuri Pasholok, Igor Zheltov, Kirill Kokhsarov
Tank Archives: Wrong Place, Wrong Time – Yuri Pasholok
IS-2: Struggle for the Assembly Line | Warspot.net – Yuri Pasholok
Not in the amplitude of the | Warspot.ru -Yuri Pasholok
Muzzle wedge for heavy tank | Yuriy Pasholok | Zen (dzen.ru) – Yuri Pasholok
Tank Archives: Improving the IS-2 – Peter Samsonov
“>Russian Heavy Tank Object 244 – The Original IS-3 (thedailybounce.net) -Harkonnen
IS-2Sh – unusual “Stalin” (voentex.ru)

WW2 Soviet KV-4

KV-4 (Object 224) K.T.T.

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–

KV-4 designs

Placement	Name	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
4	Ermolaev KV-4	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

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
Total Production	0, blueprints only

Sources:

Breakthrough tank KV – Maxim Kolomiets
Supertanki Stalina IS-7 – Maxim Kolomiets
KV 163 1939-1941 – Maxim Kolomiets
KV heavy tank – compiled by E.V. Egers
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
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
Tank Archives: Modernization on Paper
Опытный танк с боевой биографией | Warspot.ru
Тарапатин П.С. (famhist.ru)
Танкостроение на грани здравого смысла | Warspot.ru
Soviet heavy tanks series kv. History of creation External fuel tanks tank KV 1 (ezoteriker.ru)
About the forgotten creators of Soviet armored power. (historyntagil.ru)
Revolution Dingxin (1) – I love to look at the bib (wakwb.com)
Soviet heavy tanks 45-65 – 0020.htm (narod2.ru)

WW2 Soviet KV-4

KV-4 (Object 224) Kresavsky

Post author By Pavel Alexe
Post date September 28, 2022
2 Comments on KV-4 (Object 224) Kresavsky

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–

KV-4 designs

Placement	Name	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
4	Ermolaev KV-4	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

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, Kresavsky 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 IS and IS-3 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 Kresavsky, 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.net

Interpretation 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
No. Built	0, blueprints only

Sources

Breakthrough tank KV – Maxim Kolomiets
Supertanki Stalina IS-7 – Maxim Kolomiets
KV 163 1939-1941 – Maxim Kolomiets
Bronevoy Schit Stalina. Istoriya Sovetskogo Tanka (1937-1943) M. Svirin
Kreslavsky M.I. (famhist.ru)
Tank building on the verge of common sense | Warspot.ru – Yuri Pasholok
Tank Archives: Soviet 107 mm Guns – Peter Samsonov
Tank Archives: KV-3 Mulligan – Peter Samsonov
Tank Archives: ZIS-6 Characteristics – Peter Samsonov

Object 212 SPG

Object 222 (T-222/KV-3/KV-6)

T-150 (KV-150/Object 150)

KV-4 (Object 224) Marishkin

KV-4 (Object 224) Sychev

KV-4 (Object 224) Kruchyonyh

T-72 Ural-1 in Romanian Service

IS-M (Sashmurin)

KV-4 (Object 224) K.T.T.

KV-4 (Object 224) Kresavsky

Soviet Union (1940-1941) Heavy Self-Propelled Gun – Only Components Built

Cracking the Mannerheim Line

Early Bunker Busters

Development

Object 212 Tractor

Further Development

From Bunker Busting to Lion Hunting

Design

Crew

Propulsion

Main Armament

Br-2 152 mm Howitzer on Turreted KV Chassis

Fate

Conclusion

Object 212 SPG Specifications

Sources:

Soviet Union (1941) Heavy tank – Partial Mock-up Built

The T-150

Development

Design

Turret

Crew

Propulsion

Armament

Fate

Conclusion

Object 222 (T-222/KV-3/KV-6) Specifications

Sources:

Soviet Union (1940-1943) Heavy Tank – 1 Prototype Built

The KV-1

More Armor

Object 221 – The T-150’s Bigger Brother

Design

Crew

Engine and Propulsion

Armament

Trials

Object 222

German Heavy Tanks

Second trials

T-150 in Combat

Conclusion

T-150 / KV-150 / Object 150 Specifications

Sources

Soviet Union (1941) Super Heavy Tank – Blueprints Only

Development

F.A. Marishkin

Design

Crew

Armor

Armament

Death of LKZ’s Heavy Tanks

Conclusion

KV-4 (Object 223) Marishkin specifications

Sources:

Soviet Union (1941) Super Heavy Tank – Blueprints Only

Development

L.E. Sychev

Design

Crew

Armor

Armament

Conclusion

KV-4 Sychev specifications

Sources:

Soviet Union (1941) Super Heavy Tank – Blueprints Only

Development

G.V. Kruchyonyh

Design

Crew

Soviet Union (1940-1941)
Heavy Self-Propelled Gun – Only Components Built

Soviet Union (1941)
Heavy tank – Partial Mock-up Built

Soviet Union (1940-1943)
Heavy Tank – 1 Prototype Built

Soviet Union (1941)
Super Heavy Tank – Blueprints Only

Soviet Union (1941)
Super Heavy Tank – Blueprints Only

Soviet Union (1941)
Super Heavy Tank – Blueprints Only

Socialist Republic of Romania/Romania (1978-2005)
Main Battle Tank – 31 Purchased from USSR

Soviet Union (1944)
Heavy Tank – Drawings Only

Soviet Union (1941)
Super Heavy Tank – Blueprints Only

Soviet Union (1941)
Super Heavy Tank – Blueprints Only