212A

Shortly before the war, heavy chassis of the KV was the basis for the development of self-propelled guns, one of them is object 212A. Work was conducted in SCB-4 LKZ under overall supervision of J. Kotin, lead designer which appointed by C. H. Golburt. Draft submitted for consideration ABTU in late 1940, developed under influence of the Soviet-Finnish war. Overcoming long-term fortification of "Mannerheim Line" was much more difficult than it thought by the Red Army General Staff, and to break trough it without the help of heavy artillery was simply impossible. In some cases, the firing of heavy guns was conducted on Finnish Dotham direct-fire, which was not always possible in a heavy fire resistance. The problem could be solved taking into service equipped with large-caliber guns ACS, but such machines not come into test trial until early February 1940, when the enemy's defenses had been breached. Since the urgent need for this kind of self-propelled gun disappeared Project T-100-Y and SU-14-1 preferred to close in favor of breaking the tank KV-2. Using this Kotin decided independently to develop the theme of heavy self-propelled guns, which could be used for attacks on fellow rear of the enemy, either on his front line of defense.

For future self-propelled gun was chosen gun Br-2-mm caliber 152.4, previously installed on the Su-14 model 1937. This artillery system created Bureau of Factory "Barricades" in 1931, the comparative tests with the gun B-30 was initially rejected, but then - for reasons not entirely clear, yet entered service. Opted for the BR-2 was less than optimal, as cannon had several design flaws, and its prototype was almost destroyed due to rupture of the barrel. Nevertheless, during the years 1937-1940., 37 guns were fired, which later became part of the heavy cannon Regiment Reserve of the Supreme Command Headquarters.

Nevertheless, for all its shortcomings (low mobility, the complexity in manufacturing, low lifespan of the barrel) BR-2 had a high capacity. The range of ammunition Br-2 consisted of two types of ammunition: high-explosive 53-PF-551 weighing 48.9 kg and betonoboynymi 53-D-551 weighing 49 kg. Muzzle velocity 53-PF-551 is 880 m / s, the maximum range shots - 25 km. In case of contact with any of these shells in a tank or armored personnel carrier was the result of their complete destruction. Structurally the instrument BR-2 consisted of a barrel (up 47.2 gauge), the gate of the piston type, mast, hydraulic brakes and hydropneumatic recuperator rollback. Loading guns - kartuznoe, but to facilitate the flow of shells from the ground had a special crane to hoist. In order to post on the basis of this artillery system HF had significantly modify the chassis. The number of rollers was increased from 6 to 7, with the rear of the distance between them has been reduced, and in the middle (less loaded) - increased. Support rollers remaining 4, however, mean changes in the layout is a driving wheel moved forward. Swivel wheel with a screw mechanism for track tensioning is now located on the back. Suspension of self-propelled guns remained independent torsion. Self-propelled caterpillar was melkozvenchatoy with a width of 660 mm tracks. Changes to the chassis were made because a full redesign of the layout. Fighting compartment was located behind and partially in the middle part of the body. Department of Management, in which he has the driver and the arrow-radio operator, was between Transmission and engine compartment. The hull was welded and assembled from rolled armor plates with thickness of 20, 30, 50 and 60 mm.

Cannon Br-2 is installed in the wheelhouse and was equipped with a telescopic sight. Pointing angles were rather modest and ranged from -3 to 15 vertical and - \ 8 on horizon. Despite the fact that the shells were now literally "at hand", the charging of severely constrained their masses. In order to facilitate the loading provided for the installation of a special pan like a howitzer M-10 heavy tank KV-2. The range of ammunition to the gun was introduced into an armor-piercing projectile weighing 51.07 kg, which had an initial velocity 860 m / s and at a distance of 5000 meters could penetrate the 40-mm sheet of armor.

To protect against infantry ACS is equipped with three machine guns, DT 7,62 mm. One of them was placed in the frontal case, the second - the aft crew compartment, the third was the zenith, and had to be mounted on a turret on the roof of the crew compartment.

Ammunition for the guns BR-2 was 47-piece rounds and 3000 rounds of machine-guns. For comparison, a tank KV-2 came with a 36 shots and 3,087 cartridges.

Since the estimated mass of the object 212A approaching the 65 tons needed for its heavy-duty engine. The main option was selected in the forced-2 with a drive centrifugal supercharger, which was supposed to reach a maximum capacity of 850 hp This would allow a maximum speed of 35 km / h and cruising range on the highway about 200 km. External link protect the radio 71-TC-3M with the whip antenna, internal communication (most likely) among the crew members - such as an intercom system, TPU or TPU-3-3bis-F.

Although the heavy self-propelled guns had lost the previous priority of the project was approved by the Project 212A ABTU and was accepted for implementation. SAU building ought to hold on LKZ, where in December 1940 and was sent a set of working drawings for the construction of the body. However, at this time the company was heavily loaded with orders for the release of the KV-1 and IS-2, on completion of which were thrown into the main forces of the Kirov in size. In addition, in April 1941 to begin preparatory work on the production of the KV-3 (the first version with a lengthened chassis and a 76.2-mm gun), so that the ACS forces have no choice.

Final assembly of the case was delayed until June 1941, and after the war was not up to the pilot "assault" self-propelled guns. Perhaps it could be brought to the sea trials, but did not have time to put LKZ chassis for ACS. As a result, self-propelled gun was disassembled object 212A to the metal.

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