Pereverzev's KV-4

• Mass: 100 tons
• Length: 9300 mm
• Width: 3800 mm
• Height: 3320 mm

Shashmurin's KV-4

1. Fighting characteristics:
1. Mass: 92 tons
2. Full length: 10 (9.5) m
3. Full width: 4 m
4. Full height: 3.25 m
5. Wheelbase: 3.15 m
6. Clearance: 0.55 m
7. Contact surface length: 6.2 (5.8) m
8. Ground pressure: 0.88 kg/sq.cm.
9. Diesel engine: M-40
10. Maximum engine power: 1200 hp
11. Top speed: 45 kph
12. Range: 200 km
13. Crew: 7

Marishkin's KV-4

The KV-4 family of tanks were built to rather loose requirements, and therefore had a very large variety of designs submitted. F.A. Marishkin's 85 ton design was one of the more reasonable ones, but it wasn't without an unusual feature. The tank had a second turret carrying a 45 mm gun on top of the main turret with a 107 mm gun.

Kreslavskiy's KV-4

KV-3 Mulligan

"Proposal regarding the decree issued to the Kirov and Izhor factories

1. The Kirov and Izhor factories propose a new tank instead of the KV-3 approved by USSR SNK and CC or the VKP(b) decree #548-2332ss issued on March 15th, 1941, with increased armour according to USSR SNK and CC or the VKP(b) decree #827-345ss issued on April 7th, 1941.
2. This tank will effectively be a KV-4 tank in armament, dimensions, transmission and suspension design, engine power, and overall layout, but with thinner armour.
3. Decree #827-345ss issued on April 7th, 1941 ordered production of KV-3 tanks in 1941 that only differed in armament and armour thickness from the KV-1 and KV-2, so that factories could produce tanks they were used to, with the aim of producing KV-4 and KV-5 tanks in 1942.
4. I consider it reasonable to leave the KV-3 with 120 mm of armour in the front and 90 mm in the side, armed with the 76 mm ZIS-5 gun, built using KV-1 components, according to attached tactical-technical characteristics.

Chief of the Main Auto and Armour Directorate of the Red Army, Lieutenant-General of the Tank Forces, Fedorenko

Soviet Rear Turret Tanks

The idea of a rear fighting compartment was first implemented in several KV-4 projects. This concept was picked, for example, by K.I. Kuzmin, P.S. Tarapanin, and V.I. Tarotko, who took second place in the tender. Other engineers, for example, K. Buganov, picked that layout as well. It was explored several times more. In the spring of 1944, N.F. Shashmurin proposed a modernization of the IS-2. This tank had 5 crewmen, two of which were in the front, in the driver's compartment, and 3 were in the turret. The turret was in the rear of the hull, and the engine compartment was in the middle. The Object 705A, a competitor of the Object 260, took a similar shape. The rear fighting compartment layout was not unpopular among Soviet designers. However, each time the development stopped at the drawing board.

Heavy Tank Costs

"To the Chief of the BTU, Military Engineer 1st Grade, comrade Korobov

Following decrees issued by the Government, the Kirov factory is building a series of experimental vehicles without having any contracts for them. Letter #6109 sent on November 15th, 1940, asked you to send these contracts. Letter #2239/s sent on February 20th, 1941, repeated the request. Nevertheless, we have not received any contracts from you.

I am sending you a report of the approximate cost of experimental works performed by the Kirov factory in 1941 regarding Objects ##150, 220, 221, 212, and KV-3, for the sum of 5,350,000 rubles in total. Please send us the information to issue bills regarding these projects.

KV-4 Initial Proposal

Upon learning of the German 105 mm Flak 39 and its potential conversion into a tank gun, Soviet tank engineers began development of the superheavy KV-4 tank. However, the initial requirements were a lot more reasonable than what ended up winning the design competition.

"Tactical-technical Requirements for the Design and Production of an Experimental Heavily Armoured Tank

1. Purpose of the tank:
1. Fighting enemy heavy tanks.
2. Destruction of concrete fortifications and heavy engineering structures.
3. Destruction of enemy artillery and personnel.
2. Mass: 70-72 tons.
3. Armour:
1. Front plate: 130 mm
2. Side: 125 mm
3. Turret side at an angle of no less than 30 degrees: 130 mm
4. Roof and floor: 40 mm
5. Other plates: equivalent to side armour
4. Armament:
1. One 107 mm gun:
1. Horizontal range: 360 degrees
2. Vertical elevation: 15-17 degrees
3. Vertical depression: -2 - -3 degrees
2. 3 DT machineguns, of which:
1. One is coaxial with the main gun
2. One is installed in the turret bustle
3. One is installed in the front of the hull
3. One PPSh submachinegun
4. One flamethrower
5. Ammunition:
1. Shells and propellant for the 107 mm gun: 70-80
2. Rounds for DT machineguns: 4000-4500
3. PPSh rounds: 450-500
4. Hand grenades: 25-30
6. Tank performance:
1. Maximum speed: 35 kph
2. Maximum off-road speed: 20 kph
3. Maximum grade: 37-40 degrees
4. Height of a climbable wall: 1.2 meters
5. Clearance: at least 450 mm
6. Ground pressure without submerging the track: 0.85-0.9 kg/cm^2
7. Engine:
1. 1200 hp diesel engine
   Temporarily use 850 hp diesel engines.
2. The fuel and oil reserves in the tank must allow for at least 10 hours of driving.
3. The cooling system, lubrication system, and fuel system must allow the engine to work normally for 10 hours of continuous motion in any mode of operation with external temperature range of -40 to +40 degrees.
8. Transmission and suspension:
1. The transmission must be of the planetary type, and the suspension must be of the KV type, allowing for normal operation and control of the tank. Temporarily, a mechanical transmission is allowed, but the tank must be easily controlled with the aid of servo motors.
2. The brakes of the tank must hold it on a 45 degree slope at any movement speed.
9. Tank crew:
1. The tank crew is composed of 6 men: commander, gunner, loader, mechanic in the turret (assistant loader), driver, radio operator in the hull.
2. The driver must be able to see both fenders in front of the tank with his observation devices.
3. The maximum amount of effort expended by the driver to turn the tank must be 15-20 kg, and the maximum amount of effort to depress the clutch must be no more than 25-30 kg."

CAMD RF 38-11355-6

KV-4: At the Edge of Insanity

On March 11th, 1941, Soviet intelligence reported on the production of new German heavy tanks. The largest of them, Type VII, allegedly had a mass of 90 tons and was armed with a 105 mm gun. Soviet high command took this report very seriously. Design work started to create a worthy opponent for German heavy tanks. The result of this work was the creation of several unusual projects: KV-4 and KV-5.

Fear Magnifies

The information was partially correct, as the VK 65.01 project was finished in June of 1940, and it really was indexed Pz.Kpfw. VII. One of the tanks was to be armed with a 105 mm gun, but only 20 calibers long. The design of the 36 ton VK 36.01 started in the middle of 1940, which was indexed Pz.Kpfw. VI Ausf B. This was the mass of the "Type V" mentioned in the report. Information on real vehicles ended up mixed with hearsay. This hearsay created such a stir in the Soviet Union that heavy tank designs were radically revised.

It is thought that the flywheel of superheavy tanks started spinning on April 7th, 1941, when USSR SNK and CC of the VKP(b) decree #827-345ss was issued. In reality, everything started two weeks before. Having studied the intelligence report, GAU assumed that the 90 ton tank was armed with a tank version of the 105 mm Flak 39. This gun was purchased in 1940 by a Soviet commission. Trials demonstrated that a 130 mm armour plate provided adequate defense from this gun.

On March 21st, 1941, tactical-technical requirements were composed for the tank that would be named KV-4. Its mass was estimated at 70-72 tons. The front of the hull and the entire turret would have 130 mm of armour, the sides of the hull would have 120 mm. The armament would consist of a 107 mm F-42 (ZiS-6) gun and three machineguns. A note at the end of the document said that two tanks should be made, one with a 76 mm gun (the ZiS-5 with 3-K ballistics) and one with a 107 mm gun. The tank would store 70-80 107 mm shells. A 1200 hp engine was specified as the power plant. As a temporary measure, an 850 V-2SN engine was acceptable. With the more powerful engine, the maximum speed of the tank was rated at 35 kph.

By March 27th, the draft of the decree "On the production of experimental prototypes of heavy tanks" was ready. According to it, both heavy tank prototypes were due on November 1st, 1941. The blueprints would be ready at the Kirov factory by July 17th, and Izhor factory had to have the hulls and turrets ready by October 1st. Factory #92 would deliver one 76 mm ZiS-5 and one 107 mm ZiS-6 by September 1st.

As for the engines, plans were awaited within ten days for V-2 and M-40 based designs. The V-2 was the V-2SN, but the second engine is a much more interesting proposal. This aircraft based engine was produced at the Kirov factory. Its stock power output was 1000 hp, but a supercharged 1500 hp M-40F also existed.

The sixth point in the decree contained ideas about transporting the tank by rail. The People's Commissariat of Supply Lines (NKPS) could only offer four-axle platforms with a capacity of 60 tons. Obviously, for a 70 ton tank, this was not enough.

Anyway, by April 7th, the situation changed drastically. Instead of the KV-3, a reworked T-150 with a mass of 50 tons, a new tank would be built, with the same index, a mass of 68 tons, 120 mm of front armour, and a 107 mm gun. The approach to the KV-4 changed as well. Its mass increased to 75 tons, and the armour could potentially increase to 140-150 mm. The sides thickened to 125 mm. The deadline was moved: it was now necessary to prepare the model and technical project by June 15th and the turret and hull were expected by August 15th, 1941.

This wasn't all. Instead of a KV-4 wit a 76 mm gun, decree #827-345ss instructed the Kirov factory to build a tank that would be an answer to the phantom Pz.Kpfw. VII. As the German vehicle, this KV-5 would have a mass of 90 tons. Its armament and engine would be the same as on the KV-4. The increase in mass was due to the front armour, which was 170 mm thick in the front and 150 mm thick on the sides. The crew of both tanks would be between 6 and 8 men.

According to the decree, the blueprints for this tank were due at the Izhor factory by July 15th, and full documentation with a full scale model was due on August 1st. The Kirov factory would receive a turret and a hull by October 1st, and the tank itself would be finished on November 10th, 1941.

Heavy Duty

These new requirements meant that if the tank wouldn't have to be made from scratch, the idea would have to be drastically revised. Zh.Ya. Kotin, the director of the Kirov factory design bureau, had a difficult problem that had to be solved quickly.

Zhosef Yakovlevich took the same road as the design bureau of factory #185 when developing heavy and medium tanks in the late 1930s. During development of the 115 and T-100 tanks, several variants were prepared by different groups. Kotin went one step further and included nearly all designers from the factory into the project. For extra motivation, the authors of the more successful designs would be awarded a bonus.

Work started in the middle of April of 1941. The conditions of the contest limited the engineers fairly loosely. The only constants were the engine (M-40), mass (80-100 tons) and the presence of a turret. A multi-turret layout was allowed. The main gun would be a 107 mm ZiS-6, and the military insisted on a secondary 45 mm gun. In total, 27 projects were provided for the contest. The size of this article does not permit to cover them all, so we will discuss the more interesting designs.

N.L. Dukhov was the most successful in this task. Without coming up with any excessive fantasies, Nikolai Leonidovich approached the issue conservatively and expanded the T-220 tank. The hull was somewhat lengthened and widened, increasing the number of road wheels to 8 per side. The turret was also evolutionary, resembling the T-220 turret. The T-220 also donated its commander's cupola (with some changes), equipped with a DT machinegun. The armament, a 107 mm and a 45 mm gun, was combined into a single system.

The mass of Dukhov's tank was 82 tons, the lightest of all KV-4 proposals. The armour was at the levels required by the project, and the maximum speed of the tank was on the order of 40 kph. This design won the contest.

The second place was taken by a collective design by K.I. Kuzmin, P.S. Tarapanin, and V.I. Tarotko (some sources list S.V. Mitskevich instead of Tarapanin). Kuzmin and Tarotko later proved themselves to be talented hull designers. The KV-4 tank proposed by this group was unusual. Its fighting compartment was moved to the back, and the engine was placed in the center. The main gun was placed in a casemate with a wide horizontal range. The 45 mm gun was in a separate turret. The mass of the tank was 88 kph, and the speed was estimated at 36 kph.

The third place was taken by N.V. Tseits. Nikolai Valentinovich was the most experienced designer at the Kirov factory, starting his job in the 1920s, and having a wide variety of vehicles under his belt. Tseits' design was progressive and conservative at the same time. The second gun was discarded, as he considered it unnecessary. Tseits' design is characterized by a tall turret, allowing the vertical placement of one-piece 107 mm shells. In theory, this layout would greatly ease the loader's job. In order to compensate for the tall turret, the hull was made as low as possible. A "step" separated the fighting and engine compartments.

Another project received praise, designed by A.S. Yermolayev, who proposed two variants. The first 95 ton KV-4 had two turrets. The main one had a 107 mm gun, and the second, placed in front of it, had a 45 mm gun. The second variant was the same, but the 45 mm gun turret was missing, taking 5 tons of weight with it. Yermolayev must have remembered the SMK, the development of which he was in charge of. It's worth noting that at least five other authors used the same layout as Yermolayev.

The heaviest design was by G.V. Kruchenyh, who later designed the turret for the IS-3. Like Kuzmin, Tarapanin, and Tarotko, the engine in this design was moved forward. The tank had two turrets, one on top of another. A commander's cupola with a machinegun made up the third level. Krucheniy's KV-4 weighed a whopping 107 tons. The idea of turrets stacked on top of one another came up in five other projects.

At last, let us mention the KV-4 designed by N.F. Shashmurin. Nikolai Fedorovich indexed the KV-4 and KV-5 projects "BS", which he decoded as "a madman's nonsense" (bred sumashedshevo). No one can describe what he came up with better than the man himself.

"Having received the task to design a multi-turreted cyclops among the other leading designers of the bureau, I, without the enthusiasm about that condition (just think, we just rejected the "supermarket" SMK) I made a "knight's move", rejecting turrets altogether, and doing what I once did for the KV-1, installing the M-10 howitzer in a caponier structure, a casemate. Since we just made a super-heavy KV-3 tank, I didn't think too hard about a new one. I took off the turret and repeated my previous work, a high power SPG, installing Grabin's 107 mm gun. I explained in a note that, if necessary, the gun could be removed and replaced with an infantry squad. This modification was not allowed to enter the competition, as it violated the conditions: not enough armour, mass outside the 80-100 ton range, no turrets. In order to avoid a conflict, I made a compromise. Maintaining that a superheavy cannot be a tank, I added the necessary protection, reaching about 90 tons. I kept the main gun in a casemate, but added a KV-1 turret on the roof. I.M. Zaltsmann liked the design (due to its "reasonable universality", as he called it) and I received a second place award, 1000 roubles. That was nice, I bought a fur coat for my wife."

Backup Option

On May 9th, 1941, the contest winners were annouced. Dukhov received 5000 roubles for first place. Kuzmin, Tarotko, and Mitskevich received 3000 for their second place project. Tseits, Yermolayev, and Sychev received 2000 roubles each. Shashmurin received 1500 roubles.

After that, work on the KV-4 went slowly. According to the decree, the project was due in mid June, but judging by the correspondence sent, not much progress was made towards that goal. Things got to the point that Marshall Kulik himself intervened and demanded that work speed up. No one knows how much effect that had, since his letter was dated June 12th, and the war started ten days later.

Another stakeholder, the NKPS, was doing much better. GABTU and NKPS actively exchanged mail regarding railroad platforms for new tanks since spring of 1941. The goal at first was 72 tons, but in April, the numbers changed to 80-100 tons. GABTU ordered 200 of these platforms for 1941 and 1500 for 1942. Unlike the tankers, the railroaders completed their mission. In 1941, production of six-axle 120 ton platforms began, with length and weight capacity to spare.

As for the KV-5, almost no work was done until June of 1941. According to Zaltsmann's letters, there was an idea to announce a prize for the winning KV-5 design as well, but that idea was dropped. Kotin's competition was rejected and more successful KV-4 designs were reused. As Dukhov's design was already being worked on and the front-engined tank was too progressive, Tseits' KV-4 was selected. Nikolai Valentinovich was appointed as the lead designer. Other engineers from the KV-4 contest were involved in the project: Kuzmin was designing the hull, Sychev the turret and gun mount. Fedorchuk, the most experienced designer, was given the suspension.

The KV-4 and KV-5 were in an odd place. On one hand, GABTU's position was that the KV-3, the work on which was progressing at full throttle, was a temporary solution, and would be replaced in 1942 by the KV-4 or KV-5. Which design would win would be a matter settled by competitive trials.

On the other hand, the KV-4, approved in May, had nearly no documents completed. The same could not be said for the KV-5, work on which continued even after the start of the war and the order to cease work. Even the manufacturing technology was changed. The last blueprints were dated August of 1941, when the Germans were already near Leningrad.

As mentioned above, the KV-5 was based on Tseits' KV-4. The idea of a tall turret and short hull was expanded upon and adapted to mass production. The "step" in front of the turret was removed. The driver received a personal casemate, and the hull gunner got a mini turret. Because of this, the front of the hull was only 920 mm tall. Second, the circular shape of the main turret was revised. The front armour grew to 180 mm, making it invincible to any gun of that era.

Battle of Phantoms

The development of the KV-4 and KV-5 is usually seen as a senseless waste of time and money. This is largely true. Even if the war did not start in 1941, it is doubtful that these tanks could enter mass production. However, where there's smoke, there's fire. The mistakes made by Soviet intelligence have a basis in fact.

Study of Bunderarchiv documents shows that, in March of 1941, Krupp began production of the 15 cm K. L/40 Sfl., or 149 mm self-propelled gun. In the fall of 1941, this project turned into 15 cm L L/40 fur VK 70.01. Yes, this is the very same VK 70.01, better known as Lowe or Pz.Kpfw. VII. The mass of this tank was also 90 tons, and one of the armament variants was a 105 mm gun. Perhaps this is the Pz.Kpfw. VII that intelligence discovered. In any case, this is not the VK 70.01 that is widely known now, as sloped armour was only used in Germany after the fall of 1941 when the Germans became familiar with the T-34.

Original article by Yuri Pasholok.

Heavy Tank Decree

"Decree #231s for the People's Commissariat of Heavy Machine-building
April 9th, 1941

1. On the KV-3 tank:
1. Altering Decree #548-232ss of the USSR SNK and Central Commitee of the VKP(b) issued on March 15th, 1941, I order that:
1. The front hull armour of the KV-3 must be 115-120 mm, the front turret armour must be 115 mm.
2. The KV-3 will be armed with a ZiS-6 107 mm gun with a muzzle velocity of 800 m/s.
2. Stamp KV-3 turrets for 107 mm guns with armour slopes of no less than 30 degrees, for which the director of the Kirov factory, comrade Zaltsmann, must:
1. Produce blueprints for the new turret and hull jointly with Izhor factory and provide Izhor factory with the blueprints by April 15th, 1941.
2. Produce a turret model jointly with the Izhor factory and present it to the NKO by April 25th, 1941.
3. Factory #92 must provide Kirov factory with a 107 mm ZiS-6 gun with a mount and develop a gun mantlet jointly with Kirov factory.
4. Factory #92 must provide the following amounts of 107 mm ZiS-6 guns to Kirov factory:
1. July: 45
2. August 80
3. September: 110
4. October: 110
5. November: 110
6. Before December 15th: 65
2. On the KV-4 tank:
   Director of Kirov factory, comrade Zaltsmann must:
1. Design and produce a KV-4 tank (with a lengthened chassis) according to tactical-technical characteristics approved by the USSR NKO with a ZiS-6 gun and main armour 125-130 mm thick, with the possibility of increasing some armour to 140-150 mm.
2. Assemble one experimental prototype by October 1st, 1941, for which:
1. Turret and hull blueprints must be produced and provided to Izhor factory.
2. A model and a technical project must be provided to the NKO for approval.
3. Izhor factory must finish the KV-4 hull and turret and provide it to Kirov factory by August 15th, 1941.
3. On the KV-5 tank:
   Director of Kirov factory, comrade Zaltsmann must:
1. Design and produce a KV-5 tank by November 10th, 1941. Design the hull and turret jointly with Izhor factory designers, based on the following main characteristics:
1. Armour: 170 mm front, 150 mm side, 170 mm turret.
2. Armament: 107 mm ZiS-6 gun.
3. Engine: 1200 hp diesel.
4. No more than 4200 mm in width.
   Keep the requirements for transporting the tank on the railroad in mind.
2. Provide Izhor factory with blueprints for a hull and a turret by July 15th, 1941.
3. Provide a model and a technical project to the NKO and GABTU for approval by August 1st, 1941.
   Izhor factory must finish the KV-5 hull and turret and provide it to Kirov factory by October 1st, 1941."

M. Svirin, Bronevoy Schit Stalina. Istoriya Sovetskogo Tanka (1937-1943)

KV-4 Status

The KV-4 is an almost mythical vehicle. Despite a great number of projects being submitted, it is still unknown which was finally selected. One definitely was, as characteristics were finalized, and production was scheduled. Turns out that the development of such a giant was progressing slowly.

"I report that, according to Decree #827-345ss of the SNK and Central Committee of the Communist Party signed on April 7th, 1941, Kirov factory must deliver blueprints for the hull and turret of the experimental KV-4 tank to the Izhor factory.

At this time, Kirov factory only has sketches of the tank layout, hull and turret blueprints are not finalized, and Izhor factory does not have them.

I ask for your orders to Kirov factory, instructing them to accelerate the development of KV-4 hull and turret blueprints and deliver them to the Izhor factory, since a delay might result in the completion of the prototype being late.

Marshall of the Soviet Union, G Kulik."
CAMD RF 38-11355-22

Proposed Soviet Heavy Tanks, Spring 1941

The USSR was developing tons of heavy tanks before the start of the war, with very many variations on possible designs of the KV-4 and KV-5. The characteristics of the final designs are summarized in this table.

Tank Name		T-44	KV-3	KV-4	KV-5
Mass (tons)		29.5	68	75	90
Armour (mm)	Front	75	120	130	170
	Side	60	90	125	150
	Top and bottom	30 and 23	40 and 30	50	50
Armament	Gun	1 76 mm or	1 107 mm	1 107 mm	1 107 mm
	Gun	1 57 mm
	Machineguns	3	2	2	2
Ammunition	Shells	100	50	100	100
	Bullets	6000
Engine power (hp)		600	850	1200	1200
Maximum speed (kph)		55-60	30	30	30
Fuel capacity (hours)		10	10	10	10
Crew		4-5	6	6-8	6-8

CAMD RF 38-11355-949

The T-44 is, of course, not the late-war medium tank, but the pre-war medium/heavy tank, more commonly known as the A-44. 

Eagle-eyed readers may detect some mystery in this table. Take a look at the KV-4 column. One gun, 90 tons, 170 mm of front armour, 35 kph top speed? This isn't Shashmurin's project, the one he claimed won the tender in his memoirs! 

KV-4 Armour Thickness

Monsters like the KV-4 were built for a reason. The USSR knew of powerful German AA guns that could be used in anti-tank roles, and wanted to be ready for them.

CAMD RF 38-11355-14

The first column is the caliber of the AA gun, second is the thickness of the armour in question, third is the angle of the armour, fourth and sixth are the quality of the armour for penetration and nonpenetration, respectively. Columns five and seven contain the speed at which the penetration or nonpenetration would occur. The last column indicates the type of the armour: the armour is homogeneous in all cases except 2-5, where it is surface hardened with high frequency current.

The conclusions are as follows: "In order to protect the tank from the 105 mm AP shell at all distances, it is necessary to have 130 mm of armour minimum, with high hardness (2.8-3.2) or surface hardened with high frequency current. Even under these conditions, the armour will be breached when hit at 800 m/s at normal."

KV-4 Rewards

"Order #40

On the Kirov factory on May 9th, 1941

1. After examination of 27 KV-4 projects proposed to SKB-2, presenting a series of solutions for development of new war machines, I remark on several projects focusing on increasing the firepower of the tank, and the project that uses components from currently produced vehicles, considering the manufacturing possibilities of the factory and its economics.
2. The KV-4 project that uses predominately KV-3 components is approved.
3. The following engineers contributed useful and original ideas, and are rewarded as follows:
1. Buganov: 1000 rubles
2. Duhov: 5000 rubles
3. Ermolayev: 2000 rubles
4. Kalivoda: 500 rubles
5. Pereverzev: 500 rubles
6. Kuzmin, Mitskevich, Tarotko: 3000 rubles
7. Moskvin: 1000 rubles
8. Tseits: 2000 rubles
9. Sashmurin: 1500 rubles
10. Bychkov: 500 rubles
4. Issue 3100 rubles to the Chief Engineer of the 1st department, comrade Kotin, for payment of engineers working on the KV-4 project and subsequent payment of the engineers working on the KV-5 project

Director of the Kirov factory (Zaltsmann)"

The project that was considered the winner was, for some reason, Shashmurin's project (at least according to his memoirs), which resembled a KV-1 with a 107 mm gun in the hull.

According to Gennadiy Petrov, a Russian historical collector that knew Shashmurin personally, he was not a fan of his creation. One of the copies of the blueprints was marked "BS" on the back, which, according to the author, stood for "bred sumashedshego" (mad man's lunacy). 

Prototype KVs

Despite the superiority of the KV over any other tank in armour and armament in 1940, the Soviet Union did not stop developing heavy tanks. Intelligence about thick armour and high penetrating guns of the potential enemy led to bigger and better tanks being developed.

KV-3 (Objects 150, 221, 222, 223)

The first is the KV-3 (Object 150). Unlike the later tank with that same name, this was essentially a slightly better KV-1, with 90 mm of armour and an improved F-32 gun (early KV-1s had the L-11 gun). The KV-3 also had a commander's cupola. However, the thick armour increased the tank's mass to 51 tons, which was too much for the engine. Regardless, the vehicle passed trials. Only one was built before the war. It was lost in battle defending Leningrad with the 123rd Tank Brigade. This tank is also known as "first KV-3", or T-150.

KV-3 (Object 150). The only immediately apparent difference between this and the KV-1 is the presence of a commander's cupola. From Solyankin et al, Soviet Heavy Tanks 1917-1941

KV-3 (Object 221) was developed with an 85 mm gun, but was never built. KV-3 (Object 222) with the F-34 76.2 mm gun met the same fate. In 1941, an electromechanical transmission was developed, but never built. KV-3 (Object 223) was the most impressive of the lot, with up to 120 mm of sloped armour, and a 107 mm ZiS-6 gun. It was never built. However, a KV-1 with a lengthened hull was built, and artificially loaded to 70 tons, in order to see if the torsion bar suspension could handle that kind of weight. It could, but the rubber tires would have to be reinforced.

KV-3 (Object 223). Model and inside. From Solyankin et al, Soviet Heavy Tanks 1917-1941

In April of 1941, it was decided that all KV-3s needed 120 mm of armour in the front of their turret and hull.

KV-220 (Object 220)

The KV-220 was another development of the KV-1. It had unsloped turret armour plates, but a roomier turret, and an 85mm F-30 gun. Armour was improved, up to 100 mm. The tank had an improved transmission compared to the KV-1. The prototype were sent to defend Leningrad with the 124th Tank Brigade, re-equipped with a 76 mm F-32 gun. The old turret was used as a part of an artillery battery. The tank was lost in battle, later repaired, and sent to a training unit.

KV-220. From Solyankin et al, Soviet Heavy Tanks 1917-1941

KV-220 being transported by crane in the background. The seventh road wheel and fourth idler are clearly visible.

An order to assign new vehicles to the 12th Independent Training Tank Regiment. A tank model "For the Motherland", serial number 220-2, engine number 1193-03 is the KV-220 that survived. CAMD RF 3674-47417-2

KV-4 (Object 224)

At the same time, another group of engineers was developing the KV-4. The tank would have a 107 mm gun, a 45 mm gun (76.2 mm in one project), and light and heavy machine guns. Some versions were equipped with a flamethrower. The powerful engine would accelerate the KV-4 up to 51 kph, depending on the project. The armour was even greater than that of the KV-3, at up to 180 mm. The mass of the tank was up to 100 tons. Over 20 designs were proposed, some are available at the Russian Wikipedia page. The most interesting ones are Kruchenyh's design (9 crew members, 180 mm of armour, 107.7 tons), Yermolayev's design (51 kph max speed), Shashmurin's design (76 mm gun in the turret, 107 mm gun in the hull), Mihailov's design (50 kph, 180 mm of armour), and Tarapatin's design (107 mm gun turret with limited traverse). Visually interesting designs are included in this article.

Three designs of the KV-4 by Shashmurin, Tarapatin, and Fedorenko, illustrating the many unconventional shapes a KV-4 could have taken.

KV-5 (Object 225)

The KV-5 projects had the same armament and engine as the KV-4, but even more armour than most of those projects (150-170 mm).  The mass was projected to increase to 100 tons. The project was meant to be finished in October of 1941, but the start of the war interfered. Simplifications to the tank had to be made, such as replacing the stamped turret with a welded one, and a single 1200 hp engine with two 600 hp ones.

The start of the war defined the priorities of KV production.

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"By order number 1217-503ss from May 5th, 1941, the production of tanks at the Kirov factory is outlined as follows: the primary tank for 1941 will be the KV-3, and, depending on the trials of the KV-4 and the KV-5, one of these three vehicles for 1942. 

The Chelyabinsk Tractor Factory will keep producing the KV-1 with 75 mm of armour. There is a possibility to, without radically altering the production process, to increase the protection of the tank by increasing the armour to 90 mm. 90 mm thick armour that is hardened by high frequency electric current is equivalent to 100-110 mm of armour. 

An experimental prototype of a KV tank with 90 mm of armour is being developed at the Kirov factory, (order number 1288-495ss) that uses the same configuration as the KV-1, aside from the gun. The factory tests are producing satisfactory results. 

Based on this, it is possible for the Chelyabinsk Tractor Factory to, starting with January 1st 1942, begin producing KV tanks with 90 mm of armour and 76.2 mm model 1940 guns. 

This decision will allow for:

1. Increasing the second manufacturing base for powerful tanks.
2. Production of spare parts for existing KV-1 and KV-2 tanks.

Please confirm these developments.

Marshal of the Soviet Union G. Kulik."

However, as the war went on, it became abundantly clear that heavily armoured tanks were to be replaced with fast ones, and powerful expensive new guns were not needed. The upgraded version of the KV-1, the KV-1S, had less armour, and not more. Later KVs with the numbers 6 through 12 were either KV-1 tanks with modified armament or, in the case of the KV-7, a radically different vehicle.

Soviet 107 mm Guns

Even before WWII, before the Tigers and Panthers, before the Ferdinands and Maus tanks, the rumours of the next super-armoured and super-powerful heavy tank were floating around. Whether it was the Neubaufahrzeug, B1, or some other menace from a potential enemy, the USSR had to be able to defend against it. 107 mm was the caliber of choice, perhaps due to the already available 107 mm field gun model 1910, modernized in 1930. However, even before the war, this gun was deemed not powerful enough, and a new 107 mm gun model 1940 was built. The length of the gun increased, from 38 calibers to 43. However, this was still a field gun, unsuitable for installation in a tank.

In 1941, during a phone call to Stalin, Grabin expressed the need for "a powerful tank gun, capable of penetrating armour of the tank that carries it at 1000 meters". Stalin suggested that the gun should be even more powerful than the modernized 107 mm gun. The 107 mm tank gun ZiS-6 was produced in only 38 days. Another 107 mm gun was considered, the F-42, but it was too bulky to install in even the KV-2's roomy turret. However, several parts of its aiming and loading mechanism were borrowed for the ZiS-6.

But that's not the most powerful gun of that caliber that was built. In 1938, a gun of unprecedented power was ordered. 107 mm in caliber, 70 calibers in length, capable of penetrating a 160 mm armoured plate sloped at 30 degrees, from a kilometer away! All this, at 10 rounds per minute.

Let's see how all of these guns fared.

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The table above demonstrates calculated penetration data against an armoured plate at 1000 meters, angled at 30 degrees from horizonal. The rows that interest us are in the middle.

The 107 mm gun model 1910/30 penetrates a respectable 81 mm at this distance. Even this was enough to defeat the armour of any German tank in 1941. The upgraded model 1940 gun (M-60) penetrates a more impressive 100 mm. This is enough to take out a Tiger from the front, a whole two years before a Tiger was even built. The ZiS-6 gun lives up to its promise of being able to penetrate its own tank's armour at 1000 meters (this gun was meant for the rather beefy KV-3 tank), with 115 mm of penetration. The "107 mm high power gun (experimental)" achieves 188 mm of penetration. That's enough to pierce a Tiger tank front to back! 

There was also another 107 mm gun project, the M-75, an upgrade over the M-60, just a year after it was built. Mounted on the ML-20 carriage, it could penetrate 165 mm at 30 degrees, at 1000 meters. That one didn't make it in time for the chart above, but it exists in another document.

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When the war started, Germany turned out to not have any super-powered monsters in its arsenal at all. Instead of making overpowered guns that could penetrate the strongest enemy armour 3 times over, the USSR focused on making cheaper guns, for lighter tanks. The KV-3, KV-4, and KV-5 programs were shut down, and the 107 mm high power guns went with them.