KV-13 object 233
The last attempt to seriously improve the characteristics of the KV was made in the middle of 1942 and led to the appearance of the KV-13, sedignated “Medium Heavy Armor Tank”, which is fundamentally wrong. From the outset, the KV-13 was designed as a heavy tank. The revolutionary machine fully met the new requirements of the Soviet military. It became the first maneuverable heavy tank, whose solid for that time reservation was combined with a relatively small mass, and most importantly - with high mobility. Cases where cars became epochal, never reaching mass production, are not uncommon in the history of tank building. The Soviet KV-13 tank belongs to their number. The KV-13 appeared in a very difficult time, partly for this reason, he never went into the series. Nevertheless, the further development of the Soviet tank building occurred under the influence of the latest development of the talented designer Nikolai Valentinovich Tseyts.
Since the huge mass of the tank could only be reduced by reworking its chassis on the KV-13, it was shortened by one support roller, with the result that the hull length was reduced to 6650 mm and width to 2800 mm. In terms of weapons and equipment, the medium tank did not differ from the KV-1. On tests conducted in the fall of 1942, the KV-13 did not perform well in the first place — the car was constantly breaking down, and in terms of the sum of the characteristics it turned out to be worse than the T-34. However, the path chosen by the designers turned out to be correct and subsequently led to the appearance of much more successful tanks, the IS-1 and the IS-2.
From the first days of the German invasion of the USSR, information about the inadequate operational reliability of heavy KV tanks began to come in from the fronts in large numbers. As stated in the reports, the technical and driver’s staff turned out to be very poorly trained and could not even provide routine maintenance of military equipment. In addition, the summer heat and high dustiness played a role, due to which the engines often failed. Another significant drawback of HF was its large mass. If the early samples of the KV-1 weighed about 47-48 tons, after increasing the thickness of the armor, the mass of the serial tank increased to 50 tons. Not every bridge could withstand such a tank, and the KV’s passability through the marshland was simply “zero”. It was about the above reasons that less than 30% of the total number of tanks that participated in the battles in the summer of 1941 were lost.
Measures to reduce the mass of the KV-1 began only in the autumn, formalizing the case in the spring of 1942. At first, they tried to solve the problem with "half measures" - the next decree of the NPO ordered to minimize the mass of tanks by removing additional fuel tanks, mounted armor and reducing ammunition. Of course, this did not affect the combat capability of the KV-1 in the best way, and the tank’s speed and maneuverability almost did not improve.
Radical modernization was carried out in the early spring of 1942, when a KV-13 tank or “Object 233” design was accepted for construction . The design was carried out by a design team under the leadership of N.V. Zeitz, which included K.I. Kuzmin (corps), N.M. Sinev (turret), S.V. Mitskevich (undercarriage), and G.N. Moskvin (general layout). In early March, the People's Commissar of the Tankoprom was reported the following: "The layout of the new tank was developed, in which, due to the use of liquid armor, compaction of the layout, as well as reducing the dimensions of the hull and turret, it was possible to significantly reduce the weight compared to the KV-1."
The composition of weapons, equipment, power plant and crew of the tank remained unchanged. The People's Commissar approved the project and issued an extraordinary order for the construction of a prototype. In fact, the Zeitsk design bureau was to create a symbiosis of powerful KV armor and T-34 mobility, in connection with which the KV-13 was referred to as "medium heavy booking tank."
The undercarriage underwent the strongest changes, where instead of 6 road wheels, 5 modified structures were used. The width of the KV-13 at the same time decreased to 2800 mm, and the length of the hull was 6650 mm. The tank turret, although it retained its similarity with the KV-1s turret, acquired a more streamlined look. Almost all the main structural elements were cast, which made it possible to reduce the internal unused volume and bring the frontal armor of the hull to 120 mm and the turret to 85 mm, thereby surpassing the serial KV-1. An interesting feature of this tank was the minimal use of non-ferrous metals.
The KV-13 was assembled as soon as possible and in the first half of May the tank was presented for testing, but before that the supporting and supporting rollers of the new tank, as well as lightweight tracks, were tested on the serial KV-1. In the course of running tests, it turned out that with a mass of 32,400 kg, the tank achieves a maximum speed on the highway of 51.7 km / h and is almost similar in mobility to the T-34-76. However, the weight characteristics of the KV-13 still did not meet the requirements, so at the end of June we developed an option with tracks from the T-34 500 mm wide.
As a backup option, the use of standard tracks was left in conditions of strong mudslides. In the summer of 1942 they planned to carry out full-scale tests of the KV-13, but on June 15 there was an order to suspend work on it and concentrate all its efforts on the production of serial products. Nevertheless, it was found out that the chassis and transmission of the tank are extremely unreliable. Very often the gearbox broke, the track rollers and tracks collapsed, the caterpillar flew off at sharp turns, the engine overheated. In combat, the KV-13 also turned out to be worse than its predecessor - due to the tightness in the fighting compartment, it had to be removed from the gunner’s crew, transferring its functions to the commander of the vehicle.
On the question of finalizing the KV-13 returned only in the fall, when N. F. Shashmurin was appointed the lead designer, instead of the deceased NW Tseyts, who had suddenly died. The new manager proposed to use the transmission previously developed by FA Marishkin for the KV-1s on an experimental tank, but here too the luck was not accompanied by Soviet engineers. The reason for this was the heavy congestion of the tank.
In September 1942, an experimental KV-13 prototype was shown to I. Zaltsman, the People's Commissar of the Tank Industry, having been silent, however, about some of the faults identified. Since this tank was again among the top priority projects, its refinement was continued. In addition to eliminating the deficiencies at KV-13, in October 1942 they planned to install a three-seat turret. However, this process soon became protracted. Every time the tank was sent to the test stie, it failed for a variety of reasons - apparently the number “13” in the name of the tank played its unhappy role. Over the next month, the KV-13 replaced not only the elements of the chassis, but also the electrical equipment, cooling elements and final drives.
The seemingly good security of the tank did not become an “outlet” either. For two days, on September 11 and 12, 1942, the KV-13 was subjected to artillery shelling at the testing ground near Sverdlovsk. They fired from a distance of 50 meters, but by hanging various powder charges simulated shooting from a distance of 400, 600 and 1000 meters. A total of 14 shots were fired from a 76-mm tank gun and 8 shots from an 88-mm German anti-aircraft gun, the analogue of which was mounted on tagras and panthers. Five shells fired from the German guns struck the frontal armor, which made the engineers think about strengthening the reservation to 120 mm. True, in this case, the mass of the tank would noticeably exceed the 30 tons specified in the TTZ.
Since the further improvement of the first prototype of the KV-13 was clearly at an impasse, it was decided to build a second specimen. They installed a three-seat turret on the chase 1540 mm with armor thickness 90-110 mm, and the frontal armor was brought up to 120 mm. The mass of the tank increased to 38 tons, which somewhat reduced the maximum speed. In a report dated February 1, 1943, Deputy Commissar Z.Ya.Kotin reported that the KV-13 on the battlefield will have mobility no worse than that of the T-34, having also better security. It required "only" to modify the constantly failing gearbox. The next stage of modernization led to the appearance of two experimental tanks, the Sample No. 1 IS (it retained the designation “Object 233”) and the Sample No. 2 IS (“Object 234”). In order to accelerate their construction, the STB ordered to use the available experienced KV-13, to refine their design and make a number of changes. In addition to the improved design, the IS #1 received the F-34M gun, and the IS #2 was equipped with a 122-mm howitzer U-11 and a turret from the KV-9.
A wooden model of the first IS was assembled in March 1943 simultaneously with the construction of the hull and the turret, and a few weeks later both prototypes and the serial KV-1s were sent for comparative tests. By April 1, the IS “Sample No. 1” passed 489 km, the IS “Sample No. 2” - 405 km, KV-1s - 475 km. No serious remarks were made on the running properties; they only noted that two MK-IV viewing devices should be installed on the tanks, a single-type commander's turret should be installed, the engine should be modified and the defects noted immediately eliminated. However, the weapons of the experienced IS tanks did not pass the tests. Of the 15 shots made from 122-mm howitzers from a distance of 400 meters, none of the shells hit the target. As for the 76.2 mm F-34M cannon, it could penetrate only the onboard and aft armor of the "tiger" from a distance of less than 200 meters,
The result of this story was obvious - neither the KV-13 nor the experienced IS tanks went into mass production. Nevertheless, the work on them was useful in the construction of a heavy tank IS-1, which entered service in late 1943.
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