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.
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.
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.