IS-1 / IS-85 Heavy Tank (Object 237)
The IS 1 tank and the IS 2 tank are the first in a series of heavy IS tanks. They were developed during the Great Patriotic War and began to be produced in 1943. The Soviet tanks KV 1 and KV 13 were taken as the basis. The prerequisite for the creation of new tanks was the appearance of the Tiger model in service with the German army. The combat use of IS 1 in the history of the Great Patriotic War was unsuccessful, since the tank’s guns could not always penetrate the armor of the enemy’s combat vehicles.
After the start of the Great Patriotic War, with mass production of tanks in the eastern part of the USSR, head of the OGK NCTP S.A. Ginsburg proposed to create a single tank, which should have been cheaper and easier to manufacture than not only KV, but also T-34. On 6-11 December 1941 in ABTU, a group of designers of the Chelyabinsk Kirov Plant (CHK) presented sketch project of a 30-ton "medium tank reinforced KV-13 ("Object 233"). The main feature of this project, included in the pilot work plan, was the widespread use of armored casting to reduce the need for a large thickness armored vehicle. The casts were made not only the turet, but also the main elements of the hull.
On the basis of the order of the NCTP No.55 of the March 23, 1942 in Chelyabinsk on the basis of the evacuated SKB-2 Kirov plant and the local Experimental Tractor Plant was formed by the Experimental Tank Engine Plant No.100, to which all works on Object 233 were handed over. According to the plan, by May 1, 1942, the first prototype KV-13. The tank's weight was 31.7 tons. SIS-5, two 7.62 mm DT machine guns. The thickness of the hull's frontal armor reached 120mm, and turret 85 mm. The B-2K engine with a maximum capacity of 600 hp. Elements of its chassis, including the caterpillar, took from the T-34, and the supporting rinks borrowed from KV. Original 9-speed gearbox with a triple demultiplier, it was installed in a single-stage planetary on-board gearboxes, to reduce the width of the tank mounted inside the leading wheels. The cannon was mounted with ball supports in a two-seater turret (1420 mm) and had a ammunition of 65 Shots. A savvy, improved radiator was used on the KV-13 type of T-50 light tank installed earlier on the One O.J. (a variant of the Kirov plant). It is noteworthy that, with the exception of the engine and electrical equipment, the KV-13 had no non-ferrous metals at all.
Factory tests of KV-13, which began in May 1942, revealed a number of disadvantages - the difficulty of providing acceleration characteristics of the transmission, destruction of supporting rinks and tracks running part, falling caterpillars on turns. At the height of the ordeal in July 1942, the presenter on KV-13 designer N.V. Tseitz died suddenly, and in his place was appointed N.F. Shasmurin. By his initiative on the KV-13 installed the gearbox and the nodes of the chassis from KV-1C (C- high-speed) tank being developed at the time. However, in this form The KV-13 tests could not withstand and work on it was stopped.
Work on the KV-13 tank managed to resume only in the autumn of 1942. It was decided to eliminate the shortcomings in the tank - it seemed that J.Y. Kotin had no doubt that this. The tank will be adopted under the name IS ( "Joseph Stalin" ), so the new machine was designated "Object 233IS" . The feature of its transmission became two-stage system developed by the professor A.I. Blagonravov. For the convenience of observing the battlefield on the roof of the new 3-seater turret (F-34M cannon) with a thickness of armor 90-110 mm (the diameter of the 1540 m) was supposed to install a command turret. The design included an improved cooling system, the tracked engine used only tank units KB-1C, while the tracked chain was facilitated by the use of odd trucks.
Continuing initiative work on the new tanks and their name had been legalized by decree of GKO No.2943sfrom February 24 1943 and by order of NCTP No.104ss, coming out the next day. These decisions by the CDC (chief designer S.N. Mahonin) and plant No.100 NKTP (this time the Experimental tank plant, chief designer - A.S. Yermolayev) was prescribed to produce and present two experimental Joseph Stalin tanks. After that, the 233IS object tank has already been received the official name of the "IS sample no.1", and amplification of tank and mechanized parts and compounds at the breakout enemy defenses" "Object 234" - "IS sample No.2".
Comparative testing of both machines and serial KV-1C, conducted March 22 to April 3, 1943 near Chelyabinsk. It was also planned participation of the first KV-13 sample, but to repair it by a specified date is not succeeded and subsequently it was used to shoot experimental Su-100. The ISs were superior to the serial KV-1C (excluding the the fact that Object 234 had broken support at maximum speed rollers and balancers suspension) and even before the end of the tests the commission came to conclusions on the following improvements to the IS tank: "I class" ... increase the internal The volume of the turret under the 122 mm cannon (U-11); make a command inge-turret A single type install two MK-IV-type observation devices (here, it seems to be Vickers Tank Periscope MK.IV Allied tanks received by the Allied Land-Lease. "RS" and one observation deck in the command turret; Improve build quality Engines continue testing IS-1 and IS-2 tanks to warranty mileage (at least 500 km); ... speed up the manufacture of the IS-1 and IS-2 installations in 10 units launched into the production of the CDC without waiting for the results of the tests to test the technology, urgently eliminating all defects marked by the commission . However, these plans were not given to be realized.
These projects (lead designer N.F. Shashmurin) returned to a well-worked six-wheel chassis, like KV-1, in the design the hull was widely tested on the KV-13 and previous IS prototypes armored casting. The new B-2IS engine was more densely composed (its height was reduced by 200 mm) and was supplemented by an all-mode regulator of the number of revs and an inertial starter. Engine resource reached 300 motor hours, fuel consumption - 188 g/l.h (against 195 g/l.h.h at KB-1C).
New cooling system and Multicyclone air purifier should have been more efficient when operating the tank. The sub-engine frame and on-board gearboxes were also changed. Also Control drives were supplemented by a servo mechanism and a control bridge Brake. Installation of small-sized designs by A.I. Blagonrava and A.S. Yermolayev (for this innovation they subsequently were awarded the State Prize) has reduced the width of the hull by 18 cm and improve the maneuverability of "Object 237" compared to KV-1C. The driver's mechanical seat moved back somewhat, placing a symmetrical longitudinal the axis of the machine, which allowed to narrow the top of the hull somewhat in front. The functions of the radio operator were handed over to the commander, for which the radio station was re-transferred to the designed turret.
Factory and beyond testing, which took place from July 1 to 15 August 1943, showed the best traversability and mobility on the ground "Objects 237" compared not only with the KV-1S tank, but also the T-34, from both the commander's and the driver's seat, but the installation on the chassis of the KV-1S the turrets of the IS tank were considered unacceptable by military representatives at the time, as it demanded the remodeling of the turret box. Object 238 tank is not going anywhere at all The S-31 gun did not fit into the close combat unit for her and he was soon withdrawn from the test. For all the testing time, the tank "Object 237" No.1 866 km, Object 237 No.2 - over 600 km, KV-85 - 285 km.
From the diary of V.A. Malyshev: "I class" ""July 17, 1943 Today was at Stalin's. [...] Told about the new heavy tank with 85 mm IS cannon - you. Stalin read carefully and said that it is necessary to quickly Move. Obviously, I liked the tank. [...] Stalin asked if the power was sufficient Diesel. I replied that it was small, the tank would be better if put on it more powerful engine - 750-800 hp Tov. Stalin gave the task seriously to create powerful diesels."
According to the results of the tests, the State Commission recommended the tank "Object 237" No.2 for adoption with the following improvements: introduce a hydraulic mechanism turning the turret like the M4A2 used on the American tank; Supplement commanding turret anti-aircraft turret; provide for the possibility of rearmament 100 mm IS tank and 122 mm cannons; provide for the possibility of adding weapons tank treasury 50 mm mortar for self-defense of the tank from the enemy's infantry; to work out the design of the broken scope of the "German type" ; provide for the possibility of placing the commander to the right of the gun, and the loader left ("i class" "under the right hand" ); to fabricate and test the turret and the hull High-hard armor tank with thickness; design and experience A two-speed diesel engine with a capacity of 800 hp on an IS tank; Experience tracked chains with rubber-metal silent blocks type.
Despite the noted shortcomings (high location of the main pedal friction, and lack of access to them in the field, increased wear and tear of the jagged crown turret's drive, poor sealing of the upper hatches, among other transmission, lack of illumination, given the Red Army's great need for new tanks, without waiting for the trials to end, it was decided to send for frontline testing the first batch of new IS tanks with the D-5T gun (no less than 20 pieces) in July 1943, but the manufacture of the front-line series of I.S. delayed, and the culprits were here as tank builders, faced with problems in the chassis and transmission of IS, as well as by the Gunners, 85 mm cannons (the D-5T gun had a large number of small parts, required precise processing, which greatly hindered its development in production). It was not until the end of July 1943 that the CDC received a small batch of D-5T guns, which immediately began to install in the new cast turrets.
The need to arm the tank with an 85-mm gun with ballistics of the 52-K anti-aircraft gun was one of the main, but by no means the only reason for the deep alteration of the IS-1. After the first stage of state tests, it became clear that the design of the tank was far from perfect. Back in April 1943, an impressive list of necessary alterations was accumulated. The design of the air intakes on the roof of the engine compartment was also unsuccessful. During the movement, dirt got into them, which could not be dealt with by the installation of protective shields. The problem could be solved only by altering the car body. The design of the driver's viewing devices caused complaints.
The chassis concept with five road wheels per side, borrowed from the T-34, was clearly unsuccessful for a heavy tank. The load on the rollers was excessive, which affected the flotation when overcoming areas with soft ground. The commission gave instructions to increase the number of road wheels to 6 per side. The increase in the length of the hull and the increase in the combat mass entailed a serious change in the chassis. As required by the task, the number of road wheels increased to 6 per board. But there were other complaints about the chassis, as a result, almost all of its elements had to be redone. With the same diameter of the road wheels, their design has been reinforced. Sloths, balancers, driving wheels changed.
The turret with the S-31 system was installed on the tank only on 8 July. The next day, factory tests began, during which the tank covered 1,543 kilometers. The average speed of pure driving was 22 km / h, and the technical speed was 19.4 km / h. The tank consumed 390 liters of fuel per 100 kilometers. During the run, a number of defects were found in the chassis and transmission. At the same time, the testers noted that the tank turned out to be more successful than its predecessor. The increase in the number of road wheels to 6. The cooling system worked effectively: in 8th gear, the tank went without overheating. Most of the testers disliked the tightness of the control compartment, the low position of the front sight and control levers, and the high clutch pedal force.
In parallel with the tests of the tank, tests of the Multicyclone air cleaner continued. It proved to be very effective, but assembly flaws were noted. Also, minor problems associated with a factory defect were found in the operation of the motor. By the way, the engines of the IS were different than those of the IS-1 or KV-1s. They received the designation B2-IS, their power was 520 horsepower at 2000 rpm.
From the diary of V.A. Malyshev: "I class" ""August 7, 1943. Again, Stalin was interested in new tanks. Said to tank is to put production for a month and a half. When I said that at that time it's impossible to do that, you know. Stalin said that by the end of the war we had this tank You don't need to. "We need the tank to fight before winter." For the first time I hear from Stalin about the end of the war. After all, you' are. Stalin gave a term of 2 months."
In view of the urgent need for new tanks with an 85 mm cannon and the absence of air-intake running parts, at the insistence of V.A. Malyshev the series production of the KV-85 tank initially rejected by the military was hastily launched. Resolution of the Red Army and the beginning of mass production came out August 8, 1943. From the diary of V.A. Malyshev: "I class""""August 17, 1943 You're going to have to do it. Stalin asked why delayed the test of IS tanks and after learning that the tank passes 2000 km run, swearing tightly and reproached for outdated norms, offered to do 1000 km".
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