"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.
This blog is dedicated to bringing World War II era documents to the general public, with an overall focus on armoured warfare. Questions? Requests? Comments? Email me at tankarchives@gmail.com or find me on Twitter @Tank_Archives.
Showing posts with label T-221. Show all posts
Showing posts with label T-221. Show all posts
Wednesday, 22 February 2017
Sunday, 7 February 2016
KV-3: Gaining Weight
After the adoption of the KV-1, it seemed that the upward trend in the weight of Soviet tanks stopped. Instead of the 60 ton SMK and T-100, the Red Army decided on a vehicle that was almost one third lighter and had identical armament and thicker armour. However, work on bigger and heavier tanks in the KV family began in the summer of 1940. The T-220 began trials in January of 1941, a tank that was heavier than either the SMK or T-100. This tank was the harbinger of a series of even heavier vehicles that were meant to replace the KV-1. First and foremost, this was the KV-3.
By Personal Initiative
The 95 mm divisional F-28 gun began trials in 1939. This gun, along with the F-25 122 mm howitzer, would become the "duplex" of divisional artillery. Despite the impressive caliber, the gun turned out very compact while retaining worthy characteristics, including those of an anti-tank gun. The F-28 could penetrate 65 mm of armour at 30 degrees at a distance of one kilometer.
It was logical to develop a tank gun with the F-28's ballistics. The project, initiated by the factory #92 design bureau, was indexed F-39. V.G. Grabin's bureau based their work on the F-34 gun. Periodically, rumours surface that the gun underwent trials in a T-28 tank, and even a photograph is shown, but unfortunately, this is a result of an improper analysis of facts and disinformation by factory #92. The photograph is actually re-touched, a practice common in factory #92 albums. The F-39 was indeed designed and planned to be tested in a T-28, but the gun was never built in metal. By the summer of 1940, interest in 95 mm guns waned, and designers switched to more powerful 107 mm guns.
On June 11th, 1940, a curious item appears in a list of proposed tank armaments. A new 107 mm gun based on the corps M-60 gun designed by factory #172 (Molotov, modern day Perm) was proposed as a replacement for the 152 mm howitzer in the KV-2. Trials showed that the M-60 could penetrate 107-110 mm of armour at 30 degrees at 800 meters. This system appears once more in a summary of tank, anti-tank and self propelled guns as "107 mm gun installed in the KV tank turret (oscillating part from the new 107 mm M-60 corps gun)". The due date for this project was November 1st, 1940, carried out by the Kirov factory.
Until now, it was not known the Kirov factory worked with such artillery systems. The design bureau did not take up this work right away, declining it initially. In January of 1941, Kirov factory proposed a high power gun to GAU with the index 412. 400-series indexes were used at the Kirov factory for artillery systems since 1940. For instance, the 152 mm howitzer in the lowered KV-2 turret was indexed 402.
412 was proposed in two variants. 412-1v was a tank version of the naval 100 mm B-24 gun. GAU rejected this design outright. The only parts of the B-24 that were reused were the barrel, shell, and casing. There was no AP shell for this caliber, and GAU fairly insisted that the nomenclature of tank guns should be compatible with field artillery. The first proposal of a 100 mm gun failed.
The second system, 412-2v, had a caliber of 107 mm. GAU proposed that Kirov factory develop this gun at their own expense, as they already refused a government proposal for a 107 mm gun in 1940. Another factory displayed initiative and made this gun by January of 1941. This ends the history of 107 mm guns at the Kirov factory.
It became known in December of 1940 that factory #92 is developing a 107 mm gun on their own initiative. Until then, no information about his new F-42 gun was sent to GAU. The new design used experience with the F-39 and F-34 guns as much as possible. As requested by GAU, the gun used the barrel of the 107 mm mod. 1940 divisional gun (the army designation for the M-60).
It was expected that the F-42 would be ready by December 25th, 1940, but work lagged behind schedule. The new gun was to be tested in the new T-220 heavy tank, but this idea was rejected, as the tank's turret was too small. On February 19th, 1941, Marshal Kulik sent a letter to factory #92 instructing them to install the experimental gun in a KV-2 turret by May 1st, 1941. The tank was already delivered to the factory by January 29th. At the same time, it was decided that an attempt would be made to equip the second T-220 prototype with the F-42, and its turret would be sent to factory #92 for installation.
New Perspective
On March 15th, 1941, USSR SNK and CC of the VKP(b) decree #548-232 was issued, ordering the Kirov factory to prepare the T-150 for production. The improved tank, with factory index 222, would be called KV-3. This was essentially a KV-1 with an F-34 gun, improved turret and commander's cupola, a more powerful V-5 diesel engine, and armour thickened up to 90 mm.
This order did not stand for long. In late March, intelligence revealed that heavy tanks were being built in Germany. It is not known what the spies meant, but the information was taken very seriously. Work on more powerful AT guns began and the KV and T-34 tanks received additional armour. Of course, plans for future tanks were also revised. In mid-April of 1941, work on a new vehicle began, even heavier than the T-150 or even T-220.
On April 7th, 1941, USSR SNK and CC of the VKP(b) decree #827-345ss was issued, establishing the characteristics of the new tank indexed KV-3. The senior engineer of this project was L.E. Sychev, later replaced with B.P. Pavlov. The new tank was indexed 223, occasionally called Object 223. Its mass was estimated at 67-68 tons, its turret armour was 115 mm thick, front of the hull was 115-120 mm thick, sides were 90 mm thick. The armament of the tank consisted of a 107 mm gun and three DT machineguns. The engine would be an 850 hp V-2SN. Until production of the V-2SN got off the ground, it was permissible to use the 700 hp V-5.
Kirov factory was freed from making spare parts for the KV-1, this task was moved entirely to ChTZ. The task of producing the "former" KV-3, now indexed KV-6, would also gradually be transferred there. It's worth mentioning that GABTU was against this decision, proposing that instead of the 223, the T-150 with a 76 mm gun with 3-K ballistics and turret and hull armour increased to 120 mm be built instead.
The new tank did not come from nothing. The KV-3 was a T-150 that was lengthened like the T-220, with a T-220-like turret mounting the F-30 85 mm gun. From the start, the turret would be produced by stamping. Even the experimental hull was not built from scratch. On February 10th, 1941, a set of parts for the T-221 (Object 221) hull arrived at the Kirov factory. This was a T-150 with a lengthened hull that was going to receive a KV-1 like turret with a 76 mm gun. The tank was supposed to be assembled by December 1st, 1940, but Izhor factory was late with parts for a series of reasons and Kirov factory had no time for it either.
Marshal Kulik's aforementioned letter proposed the installation of the F-27 76 mm gun with 3-K AA gun ballistics. This was the second prototype, assembled in the fall of 1940, as it was already called ZiS-5 by spring of 1941. These plans were not to be, as nobody touched the T-221 in February or March of 1941. The same thing happened to the hull of the 212A SPG. In April, it was finally decided that the T-221 hull will be used as a basis for the KV-3. This task was made easier by the fact that the tanks had identical side armour, and only the front had to be thickened.
Design work on the new tank began immediately after the order was received from NKTM. In parallel with the design, trials of the T-220 with a V-5 engine were held. This was the engine meant for the KV-3 before V-2SN production began. The tank, loaded to 70 tons, with the suspension sagging an extra 2-3 cm, drove 150 km between April 12th and April 15th. The missing 150 hp were felt, but the tank could drive, and the V-5 could be used as a temporary measure.
N.F. Shashmurin designed a new gearbox for the tank, a further development of the T-220's gearbox. In parallel, VAMM was tasked with developing an electric transmission. This type of transmission was developed under the direction of Professor N.I. Gruzdev at the academy previously, under its own initiative. Tactical-technical requirements were confirmed on April 29th, 1941. At the same time, requirements for a hydraulic transmission were confirmed. Employees of the All-Union Institute of Hydraulic Machinebuilding were tasked with its design.
By April 26th, a full sized model of the KV-3 was ready, which underwent preliminary inspection. As a result, the rear DT machinegun was removed, and replaced with a PPSh port. It was also recommended that the ZiS-6 (the new name for the F-42) should have a mechanical gun rammer, a travel lock in the rear of the turret, and slight improvements to the turret design. The railroaders made their changes, limiting the width of the tank to 3410 mm. It was also proposed that the round for the ZiS-6 should be one piece and that the ammunition capacity should be increased to 60 rounds.
The second time the commission reviewed the improved KV-3 model was on May 7th, 1941. Along with the model, they inspected a large amount of technical documentation. Aside from minor improvements, one major change was introduced: now, instead of the hull machinegun, the tank could mount a flamethrower designed by factory #174. The tank design was approved, but a list of a few dozen minor changes was composed.
It's worth mentioning that by now, the KV-3 was treated as a temporary measure. The thickness of its armour was based on the penetration of the 88 mm Flak 18. Looking into the future, even 120 mm of armour was seen as not enough.
Based on results of firing trials of a 105 mm Flak 39 gun purchased in Germany, it was discovered that 130 mm of armour was required for complete protection from this gun. In April 1941, a new even heavier KV-4 tank began development, then the KV-5. Everyone knew that work on the KV-4 and KV-5 would continue on for a long time, and the KV-3 remained a priority for 1941.
According to an addendum to contract #B1-081, signed on June 5th, 1941, the Kirov factory promised to make 500 KV-3 tanks in 1941. The first 55 tanks were to be built in August, then 105 in September, 110 in October and November, and 120 in December. A single tank cost 740,000 roubles. To compare, a KV-1 cost 523,000, and KV-2 cost 558,000. A German Tiger cost 400,000 Reichsmarks, or 840,000 roubles by the 1940 exchange rate. A Tiger II cost 321,500 Reichsmarks or 675, 150 rubles.
Production of the KV-3 was far away. The turret was a big problem, since, as mentioned above, it was to be stamped. As of May 13th, 1941, the tooling for its production was only partially ready, and stamping only began in mid-June. Work on the hull also lagged behind, and it began in June as well. The ZiS-6 arrived at the Kirov factory in May, but trials began in late June. This is how the KV-3 met the start of the Great Patriotic War.
Evacuation
The start of the war quickly made some changes to project work. On June 26th, 1941, NKTP order #253ss was issued, passing the production of the new heavy tank to ChTZ. The same order was sent on June 30th to Kirov factory. The order also cancelled work on the KV-4 and KV-5, but in practice, work on the KV-5 continued until the evacuation. 18 engineering designers were transferred to Chelyabinsk, including Dukhov, Pavlov, and Shashmurin. As for the experimental prototype, it was decided to assemble the hull, give it a production suspension and a T-220 engine. Stamped turrets were sent to Chelyabinsk as well as all tools to make them.
In early July of 1941, the half-assembled KV-3 and its turret were loaded on train platforms and sent to Chelyabinsk. It is said that the history of the tank ends here, since production never started, nor was the prototype ever fully assembled.
In reality, this was not so, as archive documents colourfully describe. It is known that trials of the ZiS-6 started on June 25th, after the start of the war. Trials continued until July 5th, and 618 shots were made. On one hand, trials showed good penetration, 120 mm at 1600 meters. On the other hand, the system underwent criticism regarding the reliability of certain assemblies. Conditional on improvement of reliability, the ZiS-6 gun received a green light.
The work of the factory #92 design bureau did not end here. On their own initiative, a variant of the gun called ZiS-6A was designed. Some authors mistakenly consider it a design for the KV-7 assault tank, but was not the case. What the ZiS-6A really was can be seen in this letter to ChTZ's chief engineer, S.N. Makhonin:
"We developed and are producing a system with a 107 mm ZiS-6 gun and a coaxial 45 mm gun, with the DT machinegun in the previous place. The tactical purpose of this system of obvious, conserving 107 mm shells on targets that could be destroyed with a 45 mm shell.
Due to the absence of a KV-3 at the factory, we are testing this system in a KV-2. Your engineer comrade Schneidman told us that you are making a new turret for the KV-3. Since it is advantageous to have a 45 mm gun in the KV-3 and it only requires minor changes to the turret, we ask you to widen the gun port, and change the frame and mantlet according to the attached blueprints. We do not have blueprints of the new KV-3 turret and are forced to use old ones, but the difference does not matter. At the same time, we ask you to develop an ammunition rack for 107 mm and 45 mm shells, for which we send a dimensional blueprint of a 45 mm shell."
Grabin was proposing to turn the KV-3 into a KV-4 analogue, where two guns (a 45 mm gun and a 107 mm gun) were used in Dukhov's approved design. The letter also suggests that Chelyabinsk was designing a new turret for the KV-3, since there was nowhere to stamp the old one. Sadly, by September of 1941, ChTZ had better things to do than work on the KV-3, as after the evacuation of the Kirov factory, it became the sole producer of KV-1s.
Nevertheless, it was too early to speak of the death of the KV-3. First of all, the tank was still the chassis of the 212A bunker buster, which was not cancelled. Second, the KV-3 remained in experimental work documents of ChTZ (ChKZ from the end of the year). In the plan for 1942, approved on December 22nd, 1941, the KV-3 is first, listed as work that's being transferred from the previous year which, at the very least, should be completed by assembling a prototype. The due date is May 1st, 1942. By December of 1942, a new 1200 hp two-stroke diesel engine based on the V-2 should be ready.
Unnecessary Heavy
The tank's older brother, the KV-1, dug the KV-3's grave, or, more specifically, the unreliable transmission did. Due to the thickening armour and increasing weight, the KV-1 was pursued by breakdowns. The gearbox had the most problems. In the spring of 1942, orders from above dictated that the mass of the KV-1 needs to be decreased. In these conditions, nobody needed a 70 ton KV-3.
Unfortunately, the KV-3 was never built or tested. Not because the 70 ton tank could change the course of the war, despite surpassing every foreign tank. The powerful armour would make the KV-3 a tough nut for the Germans to crack, but that was not the benefit. The main benefit was that the assembly and trials of even one of these tanks could be a wake-up call for the military, knocking off the desire for something similar once and for all.
The result of the trials could be predicted by the issues that the testers and designers of the lighter T-220 ran into. It would have been clear that such a monster could not have been pulled off the battlefield by any recovery vehicle and that transporting it on railroads would be problematic. If our tank designers earned this experience in 1941 with the KV-3, there would be no IS-7 or IS-4. The lesson that a heavy tank should not surpass 50 tons could have been learned in the early 1940s and not in 1949, after 4 years of mucking around with the IS-4 and IS-7. Sadly, history doesn't know the word "if".
Original article by Yuri Pasholok.
By Personal Initiative
The 95 mm divisional F-28 gun began trials in 1939. This gun, along with the F-25 122 mm howitzer, would become the "duplex" of divisional artillery. Despite the impressive caliber, the gun turned out very compact while retaining worthy characteristics, including those of an anti-tank gun. The F-28 could penetrate 65 mm of armour at 30 degrees at a distance of one kilometer.
It was logical to develop a tank gun with the F-28's ballistics. The project, initiated by the factory #92 design bureau, was indexed F-39. V.G. Grabin's bureau based their work on the F-34 gun. Periodically, rumours surface that the gun underwent trials in a T-28 tank, and even a photograph is shown, but unfortunately, this is a result of an improper analysis of facts and disinformation by factory #92. The photograph is actually re-touched, a practice common in factory #92 albums. The F-39 was indeed designed and planned to be tested in a T-28, but the gun was never built in metal. By the summer of 1940, interest in 95 mm guns waned, and designers switched to more powerful 107 mm guns.
On June 11th, 1940, a curious item appears in a list of proposed tank armaments. A new 107 mm gun based on the corps M-60 gun designed by factory #172 (Molotov, modern day Perm) was proposed as a replacement for the 152 mm howitzer in the KV-2. Trials showed that the M-60 could penetrate 107-110 mm of armour at 30 degrees at 800 meters. This system appears once more in a summary of tank, anti-tank and self propelled guns as "107 mm gun installed in the KV tank turret (oscillating part from the new 107 mm M-60 corps gun)". The due date for this project was November 1st, 1940, carried out by the Kirov factory.
Until now, it was not known the Kirov factory worked with such artillery systems. The design bureau did not take up this work right away, declining it initially. In January of 1941, Kirov factory proposed a high power gun to GAU with the index 412. 400-series indexes were used at the Kirov factory for artillery systems since 1940. For instance, the 152 mm howitzer in the lowered KV-2 turret was indexed 402.
412 was proposed in two variants. 412-1v was a tank version of the naval 100 mm B-24 gun. GAU rejected this design outright. The only parts of the B-24 that were reused were the barrel, shell, and casing. There was no AP shell for this caliber, and GAU fairly insisted that the nomenclature of tank guns should be compatible with field artillery. The first proposal of a 100 mm gun failed.
The second system, 412-2v, had a caliber of 107 mm. GAU proposed that Kirov factory develop this gun at their own expense, as they already refused a government proposal for a 107 mm gun in 1940. Another factory displayed initiative and made this gun by January of 1941. This ends the history of 107 mm guns at the Kirov factory.
It became known in December of 1940 that factory #92 is developing a 107 mm gun on their own initiative. Until then, no information about his new F-42 gun was sent to GAU. The new design used experience with the F-39 and F-34 guns as much as possible. As requested by GAU, the gun used the barrel of the 107 mm mod. 1940 divisional gun (the army designation for the M-60).
It was expected that the F-42 would be ready by December 25th, 1940, but work lagged behind schedule. The new gun was to be tested in the new T-220 heavy tank, but this idea was rejected, as the tank's turret was too small. On February 19th, 1941, Marshal Kulik sent a letter to factory #92 instructing them to install the experimental gun in a KV-2 turret by May 1st, 1941. The tank was already delivered to the factory by January 29th. At the same time, it was decided that an attempt would be made to equip the second T-220 prototype with the F-42, and its turret would be sent to factory #92 for installation.
New Perspective
On March 15th, 1941, USSR SNK and CC of the VKP(b) decree #548-232 was issued, ordering the Kirov factory to prepare the T-150 for production. The improved tank, with factory index 222, would be called KV-3. This was essentially a KV-1 with an F-34 gun, improved turret and commander's cupola, a more powerful V-5 diesel engine, and armour thickened up to 90 mm.
This order did not stand for long. In late March, intelligence revealed that heavy tanks were being built in Germany. It is not known what the spies meant, but the information was taken very seriously. Work on more powerful AT guns began and the KV and T-34 tanks received additional armour. Of course, plans for future tanks were also revised. In mid-April of 1941, work on a new vehicle began, even heavier than the T-150 or even T-220.
On April 7th, 1941, USSR SNK and CC of the VKP(b) decree #827-345ss was issued, establishing the characteristics of the new tank indexed KV-3. The senior engineer of this project was L.E. Sychev, later replaced with B.P. Pavlov. The new tank was indexed 223, occasionally called Object 223. Its mass was estimated at 67-68 tons, its turret armour was 115 mm thick, front of the hull was 115-120 mm thick, sides were 90 mm thick. The armament of the tank consisted of a 107 mm gun and three DT machineguns. The engine would be an 850 hp V-2SN. Until production of the V-2SN got off the ground, it was permissible to use the 700 hp V-5.
Kirov factory was freed from making spare parts for the KV-1, this task was moved entirely to ChTZ. The task of producing the "former" KV-3, now indexed KV-6, would also gradually be transferred there. It's worth mentioning that GABTU was against this decision, proposing that instead of the 223, the T-150 with a 76 mm gun with 3-K ballistics and turret and hull armour increased to 120 mm be built instead.
The new tank did not come from nothing. The KV-3 was a T-150 that was lengthened like the T-220, with a T-220-like turret mounting the F-30 85 mm gun. From the start, the turret would be produced by stamping. Even the experimental hull was not built from scratch. On February 10th, 1941, a set of parts for the T-221 (Object 221) hull arrived at the Kirov factory. This was a T-150 with a lengthened hull that was going to receive a KV-1 like turret with a 76 mm gun. The tank was supposed to be assembled by December 1st, 1940, but Izhor factory was late with parts for a series of reasons and Kirov factory had no time for it either.
Marshal Kulik's aforementioned letter proposed the installation of the F-27 76 mm gun with 3-K AA gun ballistics. This was the second prototype, assembled in the fall of 1940, as it was already called ZiS-5 by spring of 1941. These plans were not to be, as nobody touched the T-221 in February or March of 1941. The same thing happened to the hull of the 212A SPG. In April, it was finally decided that the T-221 hull will be used as a basis for the KV-3. This task was made easier by the fact that the tanks had identical side armour, and only the front had to be thickened.
Design work on the new tank began immediately after the order was received from NKTM. In parallel with the design, trials of the T-220 with a V-5 engine were held. This was the engine meant for the KV-3 before V-2SN production began. The tank, loaded to 70 tons, with the suspension sagging an extra 2-3 cm, drove 150 km between April 12th and April 15th. The missing 150 hp were felt, but the tank could drive, and the V-5 could be used as a temporary measure.
N.F. Shashmurin designed a new gearbox for the tank, a further development of the T-220's gearbox. In parallel, VAMM was tasked with developing an electric transmission. This type of transmission was developed under the direction of Professor N.I. Gruzdev at the academy previously, under its own initiative. Tactical-technical requirements were confirmed on April 29th, 1941. At the same time, requirements for a hydraulic transmission were confirmed. Employees of the All-Union Institute of Hydraulic Machinebuilding were tasked with its design.
By April 26th, a full sized model of the KV-3 was ready, which underwent preliminary inspection. As a result, the rear DT machinegun was removed, and replaced with a PPSh port. It was also recommended that the ZiS-6 (the new name for the F-42) should have a mechanical gun rammer, a travel lock in the rear of the turret, and slight improvements to the turret design. The railroaders made their changes, limiting the width of the tank to 3410 mm. It was also proposed that the round for the ZiS-6 should be one piece and that the ammunition capacity should be increased to 60 rounds.
The second time the commission reviewed the improved KV-3 model was on May 7th, 1941. Along with the model, they inspected a large amount of technical documentation. Aside from minor improvements, one major change was introduced: now, instead of the hull machinegun, the tank could mount a flamethrower designed by factory #174. The tank design was approved, but a list of a few dozen minor changes was composed.
It's worth mentioning that by now, the KV-3 was treated as a temporary measure. The thickness of its armour was based on the penetration of the 88 mm Flak 18. Looking into the future, even 120 mm of armour was seen as not enough.
Based on results of firing trials of a 105 mm Flak 39 gun purchased in Germany, it was discovered that 130 mm of armour was required for complete protection from this gun. In April 1941, a new even heavier KV-4 tank began development, then the KV-5. Everyone knew that work on the KV-4 and KV-5 would continue on for a long time, and the KV-3 remained a priority for 1941.
According to an addendum to contract #B1-081, signed on June 5th, 1941, the Kirov factory promised to make 500 KV-3 tanks in 1941. The first 55 tanks were to be built in August, then 105 in September, 110 in October and November, and 120 in December. A single tank cost 740,000 roubles. To compare, a KV-1 cost 523,000, and KV-2 cost 558,000. A German Tiger cost 400,000 Reichsmarks, or 840,000 roubles by the 1940 exchange rate. A Tiger II cost 321,500 Reichsmarks or 675, 150 rubles.
Production of the KV-3 was far away. The turret was a big problem, since, as mentioned above, it was to be stamped. As of May 13th, 1941, the tooling for its production was only partially ready, and stamping only began in mid-June. Work on the hull also lagged behind, and it began in June as well. The ZiS-6 arrived at the Kirov factory in May, but trials began in late June. This is how the KV-3 met the start of the Great Patriotic War.
Evacuation
The start of the war quickly made some changes to project work. On June 26th, 1941, NKTP order #253ss was issued, passing the production of the new heavy tank to ChTZ. The same order was sent on June 30th to Kirov factory. The order also cancelled work on the KV-4 and KV-5, but in practice, work on the KV-5 continued until the evacuation. 18 engineering designers were transferred to Chelyabinsk, including Dukhov, Pavlov, and Shashmurin. As for the experimental prototype, it was decided to assemble the hull, give it a production suspension and a T-220 engine. Stamped turrets were sent to Chelyabinsk as well as all tools to make them.
In early July of 1941, the half-assembled KV-3 and its turret were loaded on train platforms and sent to Chelyabinsk. It is said that the history of the tank ends here, since production never started, nor was the prototype ever fully assembled.
In reality, this was not so, as archive documents colourfully describe. It is known that trials of the ZiS-6 started on June 25th, after the start of the war. Trials continued until July 5th, and 618 shots were made. On one hand, trials showed good penetration, 120 mm at 1600 meters. On the other hand, the system underwent criticism regarding the reliability of certain assemblies. Conditional on improvement of reliability, the ZiS-6 gun received a green light.
The work of the factory #92 design bureau did not end here. On their own initiative, a variant of the gun called ZiS-6A was designed. Some authors mistakenly consider it a design for the KV-7 assault tank, but was not the case. What the ZiS-6A really was can be seen in this letter to ChTZ's chief engineer, S.N. Makhonin:
"We developed and are producing a system with a 107 mm ZiS-6 gun and a coaxial 45 mm gun, with the DT machinegun in the previous place. The tactical purpose of this system of obvious, conserving 107 mm shells on targets that could be destroyed with a 45 mm shell.
Due to the absence of a KV-3 at the factory, we are testing this system in a KV-2. Your engineer comrade Schneidman told us that you are making a new turret for the KV-3. Since it is advantageous to have a 45 mm gun in the KV-3 and it only requires minor changes to the turret, we ask you to widen the gun port, and change the frame and mantlet according to the attached blueprints. We do not have blueprints of the new KV-3 turret and are forced to use old ones, but the difference does not matter. At the same time, we ask you to develop an ammunition rack for 107 mm and 45 mm shells, for which we send a dimensional blueprint of a 45 mm shell."
Grabin was proposing to turn the KV-3 into a KV-4 analogue, where two guns (a 45 mm gun and a 107 mm gun) were used in Dukhov's approved design. The letter also suggests that Chelyabinsk was designing a new turret for the KV-3, since there was nowhere to stamp the old one. Sadly, by September of 1941, ChTZ had better things to do than work on the KV-3, as after the evacuation of the Kirov factory, it became the sole producer of KV-1s.
Nevertheless, it was too early to speak of the death of the KV-3. First of all, the tank was still the chassis of the 212A bunker buster, which was not cancelled. Second, the KV-3 remained in experimental work documents of ChTZ (ChKZ from the end of the year). In the plan for 1942, approved on December 22nd, 1941, the KV-3 is first, listed as work that's being transferred from the previous year which, at the very least, should be completed by assembling a prototype. The due date is May 1st, 1942. By December of 1942, a new 1200 hp two-stroke diesel engine based on the V-2 should be ready.
Unnecessary Heavy
The tank's older brother, the KV-1, dug the KV-3's grave, or, more specifically, the unreliable transmission did. Due to the thickening armour and increasing weight, the KV-1 was pursued by breakdowns. The gearbox had the most problems. In the spring of 1942, orders from above dictated that the mass of the KV-1 needs to be decreased. In these conditions, nobody needed a 70 ton KV-3.
Unfortunately, the KV-3 was never built or tested. Not because the 70 ton tank could change the course of the war, despite surpassing every foreign tank. The powerful armour would make the KV-3 a tough nut for the Germans to crack, but that was not the benefit. The main benefit was that the assembly and trials of even one of these tanks could be a wake-up call for the military, knocking off the desire for something similar once and for all.
The result of the trials could be predicted by the issues that the testers and designers of the lighter T-220 ran into. It would have been clear that such a monster could not have been pulled off the battlefield by any recovery vehicle and that transporting it on railroads would be problematic. If our tank designers earned this experience in 1941 with the KV-3, there would be no IS-7 or IS-4. The lesson that a heavy tank should not surpass 50 tons could have been learned in the early 1940s and not in 1949, after 4 years of mucking around with the IS-4 and IS-7. Sadly, history doesn't know the word "if".
Original article by Yuri Pasholok.
Friday, 5 February 2016
"Minor Modernization": T-150
The heavy KV tank, accepted into service on December 19th, 1939, was the best tank in its class. Over the course of two years, no other country could build anything like it, and the Tiger, the first proper answer to the KV, appeared on the front lines only in the fall of 1942. However, it's well known that the development of new vehicles never stops, as the military's appetites only grow. Therefore, further modernization of the KV was only a matter of time. The T-150 was the more reasonable attempt at improving the characteristics of the Soviet heavy tank.
Better, thicker, stronger
The idea that the KV was in need of improvement was announced in the spring of 1940. The KV was accepted into service with the F-32 gun, but its production was delayed, and the KV was armed with the L-11 gun until January of 1941. Even though the F-32 was a superior design, there was not much difference between the two.
Both guns were based on the 76 mm Lender AA gun mod. 1914/15 with slightly improved muzzle velocity (613 m/s from 592 m/s). On one hand, the characteristics of the L-11 were satisfactory. It could penetrate 43 mm at 1000 meters at an angle of 43 degrees. On the other hand, with 75 mm of armour, a KV tank could not destroy a tank similar to itself. Additionally, a tank gun based on the Lender gun was already designed at the Kirov factory back in 1935, indexed L-7, and work did not progress past the experimental stage. Finally, the T-34 also used the L-11, and the situation where a heavy and a medium tank have the same gun was considered unacceptable.
A reasonable conclusion was to improve the tank armament. The first point in a list of such suggestions dated July 11th, 1940, mentions the KV. According to this list, the tank needs to have a 76 mm gun with a muzzle velocity of 800 m.s to penetrate 70-80 mm of armour. The most suitable gun was the 76 mm mod. 1931 AA gun (3-K). The same proposal suggested increasing the tank's armour to 90-100 mm. The request for a new gun was issued on June 21st, 1940, in a list of tank, SPG, and AT guns in development. It was listed as "76 mm tank gun mounted in the small turret KV tank". Factory #92 was listed as the developer and the due date was September 1st, 1940.
On July 17th, 1940 (other documents list the date as June 14th), decree #128-495ss of the Council of Commissars was issued, describing the production of modernized KV tanks as well as SPGs on its chassis. According to the decree, 4 prototypes of the KV will be built. Initially, they were to differ in armament and armour. Two prototypes would have 90 mm of armour, and two 100 mm. Two tanks (one with 90 mm and one with 100 mm of armour) would receive 76 mm guns with 3-K AA gun ballistics, another two would receive 85 mm guns with 52-K AA gun ballistics, also developed by factory #92.
Work began, and some details surfaced that forced Kirov factory to redo a part of the projects. The 85 mm F-30 gun was too big for the stock KV-1 turret. As a result, three of the four tanks were radically changed. Two of them are better known as the T-220. According to the project, their mass was supposed to be 56 tons, but ended up at 62.7 tons.
The second prototype of the tank suffered the most changes. The vehicle was indexed T-221, or Object 221. It was a KV-1 with 90 mm of armour, lengthened like the T-220. The tank would likely receive an enlarged turret, as it was going to be equipped with an 85 mm gun. In February of 1941, parts of the T-221's hull arrived from the Izhor factory. In a letter written in February of 1941, Marshal Kulik proposed using the 76 mm gun with 3-K ballistics, but this never happened. As a result, the T-221's hull served as a base for the KV-3 (factory index Object 223), which was also never finished.
Factory #92 assigned the index F-27 to the 76 mm gun with 3-K ballistics. Thanks to parts commonality, there were few problems with its design. By September 2nd, 1940, the gun was installed in a T-28 and made its first 122 shots. By September 24th, the F-27 made 600 shots, and defects were discovered in the recoil system. The gun, according to reports, showed satisfactory precision. Due to improvements of the components, trials were put on pause. Assembly of a second prototype using F-34 parts began. A T-28 with an F-27 was prepared for shipment to the ANIOP (an artillery proving grounds near Mulino), but this never happened.
Practice Try
According to plans, the first KV with a 76 mm gun and 90 mm of armour was supposed to be ready by November 1st, 1940. Due to delays with the F-27, the gun was changed, and the T-150 was equipped with an F-32 gun. This tank was also called KV-150 and Object 150 in letters. Due to delays caused by Izhor factory only shipping the hull and turret of the T-150 on November 1st, 1940, the due date was missed. The vehicle was only assembled in December. It was meant to weigh 48 tons, but weighing of the prototype showed that it weighed 50,160 kg. Overall, the budget for the project was 1.5 million roubles (without armament), or a little less than three KV-1s.
The new tank was very similar to the KV-1. Externally, the tank differed by using an F-32 gun (mass production KVs started using it in January 1941) and a commander's cupola, positioned to the right of the turret. The cupola had 6 prismatic periscopes, as well as a rotating PTK periscope. Additionally, the T-150 had an improved rear DT machinegun ball.
This cupola position was temporary and not according to requirements. A new cupola was designed in November of 1940, which was similar to the cupola used in the PzIII. This is not surprising, as the tank was purchased from Germany and closely studied at all tank factories. A similar cupola, sans the rotating periscope, was used in the T-50 light tank, designed by the Kirov factory. In the T-150 turret that was built, the cupola was to the right of the gun. In the redesigned version, the commander and his cupola moved to the left. Judging by the cupola design, it would not have a hatch.
In addition to the armament and cupola, the T-150 had 90 mm of armour. Due to the increased mass, factory #75 (Kharkov) developed a supercharged version of the V-2 known as the V-5. The engine was boosted to 700 hp, but this change brought reliability problems with it.
According to NKO order #010/19s issued on January 14th, 1941, trials started on the next day. Gunnery and mobility trials were held and crew working conditions were studied. The commander's cupola came under criticism.
First, due to the small vertical viewing angle, the vision blocks were deemed insufficient. Second, it was only possible to use the cupola while standing, which was difficult to do on the move, especially in battle. Thirdly, the commander was tasked with reloading the coaxial machinegun. Finally, the commander's position made the loader's job difficult. The conclusion was obvious: move the commander's cupola along with the commander, as was done in the November 1940 project.
Gunnery trials showed that the precision of the gun was satisfactory. There was, however, a small nuance. Due to the untested gun mantlet, the gun depression was only -3 degrees instead of -6.5. The rate of fire trials were also troubling. On one hand, the rate of fire reached 5-7 RPM, on the other hand, this was only when the loader used the most convenient racks. When the racks on the left side of the tank were used, the rate of fire dropped to 3 RPM.
The biggest problem, however, was caused by mobility trials. During factory trials on January 21st, 1941, after 199 km, the engine broke down. The first few kilometers showed that the tank cannot use the third or fourth gear on a highway, as the oil overheated even when the temperature was -12 degrees. The tank could only drive normally in second gear. As of February 21st, 1941, the tank was still under maintenance: the cooling system was being redesigned. Following GABTU's proposal, trials were paused on March 1st.
Optimization
Despite a whole series of problems with the T-150, the overall direction of the work was considered correct. As the planned changes were deemed minor, the tank was given a green light. Council of Commissars decree #548-232ss issued on March 1941 ordered the Kirov factory to begin production of the KV-3. This is the index under which the T-150 would enter service. The improved version of the tank, documentation for which started development on March 16th, was indexed Object 222. This vehicle was similar to the T-150, but had an improved commander's cupola and a 76 mm F-34 gun.
The F-34 was not a final choice. GAU and GABTU were still eyeing the F-27 with its higher penetration. It was proposed that the new gun, indexed ZiS-5 in the winter of 1941, would be tested in the T-221 when it was finished. Additionally, the Kirov factory was working on its own high power tank gun.
This gun, indexed 413, was an F-32 converted to use a 57 mm barrel. Judging by the 4160 mm long barrel, Kirov factory created a tank version of the ZiS-2 gun, which was being developed by factory #92 at the time. Maximum unification with the F-32 allowed for rapid production of the gun which, most importantly, preserved the existing mount. At 1000 meters, the 413 would penetrate 84 mm of armour. In comparison, the 76 mm AA gun penetrated 70 mm of armour at 30 degrees at that range.
GAU gave an unclear answer to the 413 project on March 3rd, 1941. On one hand, the project was interesting due to its unification with the F-32. Most blueprints were done and even some parts were made. GAU proposed that the 413 be finished... but on Kirov factory's dime. The project was initiated by the factory, and GAU had no budget for it. In the end, the 57 mm tank gun project was sent to the archives.
Overshadowed by Younger Siblings
Clouds gathered over the KV-3 literally a week after production started. Military intelligence received word of German heavy tanks. The KV-3 instantly became unsatisfactory, and a new more powerful tank was ordered. It was also called KV-3, but was based on the T-220. The decision to start development of this tank, indexed Object 223, was made on April 7th, 1941.
GABTU reacted negatively to the 223 project. Yakov Nikolayevich Fedorenko, chief of GAU, sensed trouble. The T-220, T-150's older brother, killed two engines over a week of trials, and now there was a tank that weighed not 62.5, but almost 70 tons! The questions of how this monster was supposed t be transported and towed remained without an answer. On April 25th, 1941, Lieutenant-General Fedorenko proposed to cancel the 68 ton 223 and to increase the armour and armament of the 222 instead. The 54-55 ton tank would have 120 mm of front armour and a ZiS-5 gun. His proposal was rejected.
The proposed 68 ton KV-3 did not mean that lighter tanks were completely done for. On June 19th, 1941, Marshal Kulik proposed the production of a tank equal to the 222 under the index KV-6. A portion of the documentation on the T-220 was sent to Chelyabinsk. In addition, some solutions from the T-150 and T-220 migrated to production KV-1s, especially the armour.
Simultaneously with the decision to develop the 223, applique armour was added to existing KV-1s. Starting in July of 1941, the KV-1's armour was almost as thick as the T-150's. In order to test out KV-1 modernizations, the T-150 returned to testing grounds in the spring of 1941. By June 20th, 1941, the tank travelled 2237 km. The F-34 gun also eventually made it to the KV-1. It was installed in Chelyabinsk production tanks starting in the fall of 1941.
Long Living Frontliner
The start of the Great Patriotic War on June 22nd put an end to any ideas about producing the KV-6. In the end of 1941, the idea of using an 85 mm gun and a 700 hp engine appeared at ChTZ, but by early 1942 it was clear that the KV-1 does not need more weight from armament and armour, but less weight for improved maneuverability and reliability.
The fate of the T-150 was more complex than of its brothers, the T-220-1 and T-220-2. On October 11th, 1941, the tank was sent to the 123rd Tank Brigade. The T-150 is listed last in the list of tank sent from the Kirov factory, even though the last tank was sent on October 19th. As this tank was almost identical to other KV-1s (the brigade only received late KV-1s with 90 mm of armour), it is not listed in brigade documents separately.
The brigade had other exotic vehicles. In early January of 1942, U-9 was written off near Ust-Tosno, one of the KV tanks from the initial batch. An even earlier vehicle, the U-5, was received on January 12th, 1942. This tank fought in many places, ending up in the 260th Guards Heavy Tank Regiment in 1944. As for the T-150, it does not appear in the brigade's documents, but in the 31st Guards Heavy Tank Regiment the tank suddenly appears as an irreparable loss. This happened on May 18th, 1943.
The T-150's career did not end here. The tank was sent to factory #371, where it underwent major repairs. In July of 1943, the T-150 returned to the 31st Guards Heavy Tank Regiment. Its commander was Junior Lieutenant I.A. Kuksin. The tank had the turret number 220. According to the regiment's radio diagram, tank #220 had the callsign "Som" (Catfish).
On July 12th, 1943, the regiment concentrated in Maryino village in Leningrad oblast. On July 22nd, the regiment, along with the 63rd Guards Infantry Division, moved out to attack. 4th Company fought over the Arbuzovo settlement. During battles from July 22nd, to August 1943, tankers from the 31st Guards Heavy Tank Regiment claimed 10 tanks (5 Tigers, 3 PzIVs, and 2 PzIIIs), 12 pillboxes, 34 dugouts, and about 750 German soldiers and officers. The ferocity of battles can be seen in that 19 of the regiment's 21 tanks were damaged and evacuated from the battlefield, 6 of them twice. 7 tanks were repaired on the battlefield, another 13 by a repair base.
Kuksin's crew distinguished themselves. The T-150's crew claimed 5 dugouts, 2 light machineguns, and 36 soldiers and officers. During battle, the tank's track was knocked off. Under enemy fire, #220's crew repaired the track and continued to pursue enemy infantry. After that, Guards Jr. Lieutenant Kuksin's tank held a defensive line for 4 days. For this, he was awarded the Order of the Red Star.
On August 12th, 1943, the regiment was assigned to the 73rd Marine Brigade. 4th Company was tasked with attacking the Annenskoye settlement, capture the south-east outskirts, and allow infantry to reach the north shore of the Moika river. At 4:55 in the morning on August 18th, 1st and 4th Companies went on the offensive. By 6:00, 9 out of 10 tanks were knocked out. Only tank #206 from 1st Company commanded by Guards Senior Lieutenant I.P. Mikheev remained. The infantry suffered serious losses during the attack and did not achieve their objectives.
Sadly, during battles over Annenskoye on August 18th, I.A. Kuksin died. With him died his drive, Guards Technical Lieutenant M.I. Shinalskiy, and gunner, Guards Senior Sergeant A.S. Yurdin. As for the T-150, it was not listed among the irrecoverable losses. At the end of August 1943, the tank arrived at factory #371 again, but this time it was not repaired. Thus ended the career of this tank which could not, for several reasons, replace the KV-1.
Original article by Yuri Pasholok.
Better, thicker, stronger
The idea that the KV was in need of improvement was announced in the spring of 1940. The KV was accepted into service with the F-32 gun, but its production was delayed, and the KV was armed with the L-11 gun until January of 1941. Even though the F-32 was a superior design, there was not much difference between the two.
Both guns were based on the 76 mm Lender AA gun mod. 1914/15 with slightly improved muzzle velocity (613 m/s from 592 m/s). On one hand, the characteristics of the L-11 were satisfactory. It could penetrate 43 mm at 1000 meters at an angle of 43 degrees. On the other hand, with 75 mm of armour, a KV tank could not destroy a tank similar to itself. Additionally, a tank gun based on the Lender gun was already designed at the Kirov factory back in 1935, indexed L-7, and work did not progress past the experimental stage. Finally, the T-34 also used the L-11, and the situation where a heavy and a medium tank have the same gun was considered unacceptable.
A reasonable conclusion was to improve the tank armament. The first point in a list of such suggestions dated July 11th, 1940, mentions the KV. According to this list, the tank needs to have a 76 mm gun with a muzzle velocity of 800 m.s to penetrate 70-80 mm of armour. The most suitable gun was the 76 mm mod. 1931 AA gun (3-K). The same proposal suggested increasing the tank's armour to 90-100 mm. The request for a new gun was issued on June 21st, 1940, in a list of tank, SPG, and AT guns in development. It was listed as "76 mm tank gun mounted in the small turret KV tank". Factory #92 was listed as the developer and the due date was September 1st, 1940.
On July 17th, 1940 (other documents list the date as June 14th), decree #128-495ss of the Council of Commissars was issued, describing the production of modernized KV tanks as well as SPGs on its chassis. According to the decree, 4 prototypes of the KV will be built. Initially, they were to differ in armament and armour. Two prototypes would have 90 mm of armour, and two 100 mm. Two tanks (one with 90 mm and one with 100 mm of armour) would receive 76 mm guns with 3-K AA gun ballistics, another two would receive 85 mm guns with 52-K AA gun ballistics, also developed by factory #92.
Work began, and some details surfaced that forced Kirov factory to redo a part of the projects. The 85 mm F-30 gun was too big for the stock KV-1 turret. As a result, three of the four tanks were radically changed. Two of them are better known as the T-220. According to the project, their mass was supposed to be 56 tons, but ended up at 62.7 tons.
The second prototype of the tank suffered the most changes. The vehicle was indexed T-221, or Object 221. It was a KV-1 with 90 mm of armour, lengthened like the T-220. The tank would likely receive an enlarged turret, as it was going to be equipped with an 85 mm gun. In February of 1941, parts of the T-221's hull arrived from the Izhor factory. In a letter written in February of 1941, Marshal Kulik proposed using the 76 mm gun with 3-K ballistics, but this never happened. As a result, the T-221's hull served as a base for the KV-3 (factory index Object 223), which was also never finished.
Factory #92 assigned the index F-27 to the 76 mm gun with 3-K ballistics. Thanks to parts commonality, there were few problems with its design. By September 2nd, 1940, the gun was installed in a T-28 and made its first 122 shots. By September 24th, the F-27 made 600 shots, and defects were discovered in the recoil system. The gun, according to reports, showed satisfactory precision. Due to improvements of the components, trials were put on pause. Assembly of a second prototype using F-34 parts began. A T-28 with an F-27 was prepared for shipment to the ANIOP (an artillery proving grounds near Mulino), but this never happened.
Practice Try
According to plans, the first KV with a 76 mm gun and 90 mm of armour was supposed to be ready by November 1st, 1940. Due to delays with the F-27, the gun was changed, and the T-150 was equipped with an F-32 gun. This tank was also called KV-150 and Object 150 in letters. Due to delays caused by Izhor factory only shipping the hull and turret of the T-150 on November 1st, 1940, the due date was missed. The vehicle was only assembled in December. It was meant to weigh 48 tons, but weighing of the prototype showed that it weighed 50,160 kg. Overall, the budget for the project was 1.5 million roubles (without armament), or a little less than three KV-1s.
The new tank was very similar to the KV-1. Externally, the tank differed by using an F-32 gun (mass production KVs started using it in January 1941) and a commander's cupola, positioned to the right of the turret. The cupola had 6 prismatic periscopes, as well as a rotating PTK periscope. Additionally, the T-150 had an improved rear DT machinegun ball.
This cupola position was temporary and not according to requirements. A new cupola was designed in November of 1940, which was similar to the cupola used in the PzIII. This is not surprising, as the tank was purchased from Germany and closely studied at all tank factories. A similar cupola, sans the rotating periscope, was used in the T-50 light tank, designed by the Kirov factory. In the T-150 turret that was built, the cupola was to the right of the gun. In the redesigned version, the commander and his cupola moved to the left. Judging by the cupola design, it would not have a hatch.
In addition to the armament and cupola, the T-150 had 90 mm of armour. Due to the increased mass, factory #75 (Kharkov) developed a supercharged version of the V-2 known as the V-5. The engine was boosted to 700 hp, but this change brought reliability problems with it.
According to NKO order #010/19s issued on January 14th, 1941, trials started on the next day. Gunnery and mobility trials were held and crew working conditions were studied. The commander's cupola came under criticism.
First, due to the small vertical viewing angle, the vision blocks were deemed insufficient. Second, it was only possible to use the cupola while standing, which was difficult to do on the move, especially in battle. Thirdly, the commander was tasked with reloading the coaxial machinegun. Finally, the commander's position made the loader's job difficult. The conclusion was obvious: move the commander's cupola along with the commander, as was done in the November 1940 project.
Gunnery trials showed that the precision of the gun was satisfactory. There was, however, a small nuance. Due to the untested gun mantlet, the gun depression was only -3 degrees instead of -6.5. The rate of fire trials were also troubling. On one hand, the rate of fire reached 5-7 RPM, on the other hand, this was only when the loader used the most convenient racks. When the racks on the left side of the tank were used, the rate of fire dropped to 3 RPM.
The biggest problem, however, was caused by mobility trials. During factory trials on January 21st, 1941, after 199 km, the engine broke down. The first few kilometers showed that the tank cannot use the third or fourth gear on a highway, as the oil overheated even when the temperature was -12 degrees. The tank could only drive normally in second gear. As of February 21st, 1941, the tank was still under maintenance: the cooling system was being redesigned. Following GABTU's proposal, trials were paused on March 1st.
Optimization
Despite a whole series of problems with the T-150, the overall direction of the work was considered correct. As the planned changes were deemed minor, the tank was given a green light. Council of Commissars decree #548-232ss issued on March 1941 ordered the Kirov factory to begin production of the KV-3. This is the index under which the T-150 would enter service. The improved version of the tank, documentation for which started development on March 16th, was indexed Object 222. This vehicle was similar to the T-150, but had an improved commander's cupola and a 76 mm F-34 gun.
The F-34 was not a final choice. GAU and GABTU were still eyeing the F-27 with its higher penetration. It was proposed that the new gun, indexed ZiS-5 in the winter of 1941, would be tested in the T-221 when it was finished. Additionally, the Kirov factory was working on its own high power tank gun.
This gun, indexed 413, was an F-32 converted to use a 57 mm barrel. Judging by the 4160 mm long barrel, Kirov factory created a tank version of the ZiS-2 gun, which was being developed by factory #92 at the time. Maximum unification with the F-32 allowed for rapid production of the gun which, most importantly, preserved the existing mount. At 1000 meters, the 413 would penetrate 84 mm of armour. In comparison, the 76 mm AA gun penetrated 70 mm of armour at 30 degrees at that range.
GAU gave an unclear answer to the 413 project on March 3rd, 1941. On one hand, the project was interesting due to its unification with the F-32. Most blueprints were done and even some parts were made. GAU proposed that the 413 be finished... but on Kirov factory's dime. The project was initiated by the factory, and GAU had no budget for it. In the end, the 57 mm tank gun project was sent to the archives.
Overshadowed by Younger Siblings
Clouds gathered over the KV-3 literally a week after production started. Military intelligence received word of German heavy tanks. The KV-3 instantly became unsatisfactory, and a new more powerful tank was ordered. It was also called KV-3, but was based on the T-220. The decision to start development of this tank, indexed Object 223, was made on April 7th, 1941.
GABTU reacted negatively to the 223 project. Yakov Nikolayevich Fedorenko, chief of GAU, sensed trouble. The T-220, T-150's older brother, killed two engines over a week of trials, and now there was a tank that weighed not 62.5, but almost 70 tons! The questions of how this monster was supposed t be transported and towed remained without an answer. On April 25th, 1941, Lieutenant-General Fedorenko proposed to cancel the 68 ton 223 and to increase the armour and armament of the 222 instead. The 54-55 ton tank would have 120 mm of front armour and a ZiS-5 gun. His proposal was rejected.
The proposed 68 ton KV-3 did not mean that lighter tanks were completely done for. On June 19th, 1941, Marshal Kulik proposed the production of a tank equal to the 222 under the index KV-6. A portion of the documentation on the T-220 was sent to Chelyabinsk. In addition, some solutions from the T-150 and T-220 migrated to production KV-1s, especially the armour.
Simultaneously with the decision to develop the 223, applique armour was added to existing KV-1s. Starting in July of 1941, the KV-1's armour was almost as thick as the T-150's. In order to test out KV-1 modernizations, the T-150 returned to testing grounds in the spring of 1941. By June 20th, 1941, the tank travelled 2237 km. The F-34 gun also eventually made it to the KV-1. It was installed in Chelyabinsk production tanks starting in the fall of 1941.
Long Living Frontliner
The start of the Great Patriotic War on June 22nd put an end to any ideas about producing the KV-6. In the end of 1941, the idea of using an 85 mm gun and a 700 hp engine appeared at ChTZ, but by early 1942 it was clear that the KV-1 does not need more weight from armament and armour, but less weight for improved maneuverability and reliability.
The fate of the T-150 was more complex than of its brothers, the T-220-1 and T-220-2. On October 11th, 1941, the tank was sent to the 123rd Tank Brigade. The T-150 is listed last in the list of tank sent from the Kirov factory, even though the last tank was sent on October 19th. As this tank was almost identical to other KV-1s (the brigade only received late KV-1s with 90 mm of armour), it is not listed in brigade documents separately.
The brigade had other exotic vehicles. In early January of 1942, U-9 was written off near Ust-Tosno, one of the KV tanks from the initial batch. An even earlier vehicle, the U-5, was received on January 12th, 1942. This tank fought in many places, ending up in the 260th Guards Heavy Tank Regiment in 1944. As for the T-150, it does not appear in the brigade's documents, but in the 31st Guards Heavy Tank Regiment the tank suddenly appears as an irreparable loss. This happened on May 18th, 1943.
The T-150's career did not end here. The tank was sent to factory #371, where it underwent major repairs. In July of 1943, the T-150 returned to the 31st Guards Heavy Tank Regiment. Its commander was Junior Lieutenant I.A. Kuksin. The tank had the turret number 220. According to the regiment's radio diagram, tank #220 had the callsign "Som" (Catfish).
On July 12th, 1943, the regiment concentrated in Maryino village in Leningrad oblast. On July 22nd, the regiment, along with the 63rd Guards Infantry Division, moved out to attack. 4th Company fought over the Arbuzovo settlement. During battles from July 22nd, to August 1943, tankers from the 31st Guards Heavy Tank Regiment claimed 10 tanks (5 Tigers, 3 PzIVs, and 2 PzIIIs), 12 pillboxes, 34 dugouts, and about 750 German soldiers and officers. The ferocity of battles can be seen in that 19 of the regiment's 21 tanks were damaged and evacuated from the battlefield, 6 of them twice. 7 tanks were repaired on the battlefield, another 13 by a repair base.
Kuksin's crew distinguished themselves. The T-150's crew claimed 5 dugouts, 2 light machineguns, and 36 soldiers and officers. During battle, the tank's track was knocked off. Under enemy fire, #220's crew repaired the track and continued to pursue enemy infantry. After that, Guards Jr. Lieutenant Kuksin's tank held a defensive line for 4 days. For this, he was awarded the Order of the Red Star.
On August 12th, 1943, the regiment was assigned to the 73rd Marine Brigade. 4th Company was tasked with attacking the Annenskoye settlement, capture the south-east outskirts, and allow infantry to reach the north shore of the Moika river. At 4:55 in the morning on August 18th, 1st and 4th Companies went on the offensive. By 6:00, 9 out of 10 tanks were knocked out. Only tank #206 from 1st Company commanded by Guards Senior Lieutenant I.P. Mikheev remained. The infantry suffered serious losses during the attack and did not achieve their objectives.
Sadly, during battles over Annenskoye on August 18th, I.A. Kuksin died. With him died his drive, Guards Technical Lieutenant M.I. Shinalskiy, and gunner, Guards Senior Sergeant A.S. Yurdin. As for the T-150, it was not listed among the irrecoverable losses. At the end of August 1943, the tank arrived at factory #371 again, but this time it was not repaired. Thus ended the career of this tank which could not, for several reasons, replace the KV-1.
Original article by Yuri Pasholok.
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