The heavy tank IS-7 has never been mass-produced, which did not prevent it from becoming a fairly recognizable fighting vehicle, primarily due to its spectacular and memorable appearance. Numerous popular computer games in which this tank is present have also played their part. When looking at this multi-ton fighting machine and its elegant outlines of a massive tower, the word grace comes to mind, the EC-7 could safely be called a beautiful tank, just as much as this word was applicable to heavy steel monsters designed to instill fear in the enemy on the battlefield.
Variants of prototypes EC-7
In total, in the second half of 1945, the design bureau of Experimental Plant No.100 under the leadership of the famous designer Joseph Yakovlevich Kotin prepared several versions of the projects of the new heavy tank - the 258, 259, 260 and 261 objects. According to Vera Zakharova, an employee of the Museum of Armored Vehicles, the development of Soviet heavy tanks was greatly influenced by the find near Berlin of June of the year of the eroded German monster, the tank Pz.Kpfw.Maus. Given this finding, 1945 June 11, in Leningrad, developed a draft tactical and technical requirements for a new Soviet heavy tank.
Originally it was planned to create a tank with a combat mass of 55 tons, with a maximum speed of 50 km / h, armed with an 122-mm gun BL-13 with an initial velocity of the projectile 1000 m / s. In this case, the frontal armor of the new tank had to withstand hitting the shells of the same gun. Already in June, the set of tactical and technical requirements was changed. The mass of the tank increased to 60 tons, the crew grew to 5 people. The armor was supposed to provide effective protection of the tank against hits of 128-mm cannons. Not only the 122-mm gun, but also the 130-mm ballistic gun from the B-13 ship cannon were considered as standard weapons.
Work on a new heavy tank began already, based on the latest tactical and technical requirements. In September-October, 1945, the designers prepared four versions of the future tank: "Objects 258, 259, 260 and 261." They differed among themselves mainly by power plants and the types of transmission used (electrical or mechanical). Ultimately, the choice fell on the 260 Object project, which was planned to be equipped with a B-16 engine, an electric transmission and a powerful C-130 XAUMB gun mounted in a cast flat-shaped tower, which became a recognizable feature of all experienced tank models. EC-26. Despite the large mass, the tank was quite compact.
This preliminary design of the “260 Object” became the basis for the first version of the EC-7 tank, which was built in metal. However, even then it turned out that the pairing of the B-16 engines was not brought by the Soviet industry, the tests and fine-tuning of such an engine in Leningrad demonstrated its complete design unsuitability. The engine designers turned to the engine two for the reason that the country simply did not have a tank engine of the required power - 1200 hp. Ultimately, for the first prototypes of the EC-7 tank, it was decided to use the new diesel tank TD-30, which was created on the basis of the AH-30 aircraft engine. During the tests, this engine, mounted on the first two prototypes, demonstrated its suitability for operation, but due to poor assembly, it required fine-tuning.
When working on a new power plant for a promising heavy tank, a number of important innovations were partially introduced and partially tested in laboratory conditions:
- fire-fighting equipment with automatic thermal closures, triggered at temperatures from 100-110 ° С;
- soft rubber fuel tanks with a total capacity of 800 liters;
- ejection engine cooling system.
Also for the first time in Soviet tank building, designers used tracks with a rubber-metal hinge, hydraulic double-acting shock absorbers, beam torsion bar suspension, and support rollers with internal damping, operating at high loads. In total, in the process of designing a new tank, about 1,5 thousands of design drawings were manufactured and more than 25 solutions were introduced into the project that had not previously been encountered in tank construction. 20 of Soviet institutes and scientific institutions was involved in the development and consultation on the project of a new heavy tank. In this regard, the EC-7 was becoming a truly breakthrough and innovative project for the Soviet tank school.
The basic one weapons The first variants of the EC-7 tank were the 130-mm C-26 gun, equipped with a new slot-hole muzzle brake. The gun was distinguished by a high rate of fire for such a caliber - 6-8 shots per minute, which was achieved through the use of a loading mechanism. Powerful was also machine-gun armament, which later only increased. The first two prototypes used 7 machine guns: one large-caliber 14,5-mm and six 7,62-mm. Especially for this tank, the specialists of the laboratory of the Department of the Chief Designer of the Kirov Plant produced a remote synchronous-tracking electric drive of the machine-gun unit, built using individual equipment elements with foreign technology. A specially made model of a turret with two 7,62-mm machine guns installed was mounted on the stern of the tower of the experienced EC-7 and successfully passed the tests, ensuring the tank had high maneuverability of machine-gun fire.
In September-December, the 1946 of the year collected two prototypes of the new combat vehicle. The first of them collected 8 September 1946 of the year, before the end of the calendar year he managed to pass on the sea trials 1000 km, according to their results, it was recognized that the tank meets the previously specified tactical and technical requirements. During the tests, the maximum speed of 60 km / h was reached, the average speed of a heavy tank on a broken cobblestone road was 32 km / h. The second sample, assembled on December 25 1946, passed on the sea trials of only 45 km.
In addition to the two experimental tanks that were assembled by workers of the Kirov plant and had time to pass the tests at the end of 1946 and the beginning of 1947, two towers and two armored corps were made separately at the Izhora plant. They were intended for testing by shelling from modern 88, 122 and 128 mm guns. Tests were conducted on the NIBT Range of the GABTU in Kubinka. The results of these tests were the basis for the final version of the reservation of a new combat vehicle.
The whole 1947 year in the Kirovsky Design Bureau was carried out intensive work on the development of a draft of an improved version of the EC-7 tank, improvements were made to the design, including the results of tests of two experimental machines. The new version of the EC-7 tank was approved for the construction of 9 on April 1947. Despite the changes in the design, the tank was still held under the code "Object 260". The project of a heavy tank really saved a lot from its predecessors, but at the same time a large number of significant changes were made to its design.
The body of the updated model has become a little wider, the tower is even more flattened. The tank also received new curved sides of the hull, such a solution was proposed by designer N. N. Moskvin. Booking a tank was beyond praise. The frontal part of the hull consisted of three armor plates with a thickness of 150 mm, located at large angles of inclination, was implemented scheme "pike nose", already tested on the serial tank EC-3. Thanks to the proposal of Moskvin, the sides of the tank acquired a complex shape, which also increased the security of the machine: the thickness of the upper inclined sides of the hull was 150 mm, the lower concave - 100 mm. Even the stern detail of the hull had an 100 mm reservation (lower part) and a 60 mm heavily inclined upper part. The cast four-seat tower of very large dimensions, however, was extremely low and differed by large angles of inclination of the armor plates. The turret reservation was variable: from 210 mm with a total tilt in 51-60 degrees in the frontal part to 94 mm in the aft part, with the thickness of the gun mask reaching 355 mm.
The innovation of the 1947 machines of the year has become even more enhanced weaponry. The tank received a new 130-mm C-70 cannon with a barrel length 54 caliber. The 33,4-kg projectile fired from this gun had an initial speed of 900 m / s. The 130-mm C-70 tank cannon was designed at the TsAKB (Central Artillery Design Bureau) specifically for the EC-7 tank. It was a tank version of an experienced 130-mm C-69 case artillery gun created here. The gun had a vertical wedge semi-automatic bolt, and was also equipped with an electric-powered loader, similar to naval artillery. This solution allowed the tank to provide a fairly high rate of fire.
Especially for the removal of gases from the fighting compartment of the tank on the barrel of the gun was placed an ejector, and also introduced a system of purging the barrel with compressed air. A novelty for those years and Soviet tank building was the fire control system. The fire control device mounted on the EC-7 ensured that the stabilized prism was aimed at a predetermined target regardless of the gun, automatic firing and automatic casting of the gun to the stabilized aiming line when fired.
Machine gun weapons became even more impressive. The tank immediately received 8 machine guns: two large-caliber 14,5-mm KPVs at once. One large-caliber and two 7,62-mm RP-46 machine guns (the post-war DT version) were placed in the gun mask. Two more RP-46 machine guns were located in the fences, the other two were turned back and fastened outside on the sides of the tank tower. All machine guns were equipped with a remote control system. On the roof of the turret, a second 14,5-mm machine gun was placed on a special rod. It was equipped with a synchronous-tracking remote electric drive, tested on the first prototype. This system made it possible to effectively fire both ground and air targets, while being protected by the armor of the tower. The ammunition of the EC-7 consisted of 30 separate loading shots, 400 cartridges of the caliber 14,5 mm and 2500 cartridges for 7,62-mm machine guns.
The crew of the heavy tank included five people, four of them were in the turret. To the right of the gun was the seat of the vehicle commander, on the left side - the gunner. The places of the two loaders were behind the tower. They also controlled machine guns, located in the fenders, in the stern of the turret and large-caliber anti-aircraft machine gun. The driver's seat was located in the elongated bow of the hull.
The updated version of the tank EC-7 differed installation of the new engine. As a power plant, we decided to use the serial marine 12-cylinder diesel engine M-50T, which develops the power of the HP 1050. at 1850 rpm The engine was created on the basis of a diesel engine for torpedo boats. The installation of this engine, along with the use of 130-mm guns also with sea roots, turned the new tank into a real land, if not a battleship, then just a cruiser. For the first time in Soviet tank building, ejectors were used to cool the M-50T engine. At the same time, the capacity of soft fuel tanks, which were made from special fabric, was brought to 1300 liters.
From electric transmission refused in favor of the mechanical, created in 1946 year, together with the Moscow State Technical University named after Bauman. The undercarriage of the heavy tank included large diameter diameter 7 rollers (on each side), and there were no supporting rollers. Rollers were made double and had internal depreciation. To improve the smoothness of the tank, the designers used double-acting hydraulic shock absorbers, the piston of which was located inside the suspension balancer.
The fate of the project. Unclaimed power
The first prototype of the X-Numx heavy tank, the 7 of the year, began a factory test on the 1947 of August. Total car passed 27 km, after which it was sent to the ministerial bride. On tests, a tank weighing more than 2094 tons accelerated to 65 km / h. In terms of its mobility, it surpassed not only heavy but also medium tanks of its years. In this case, experts noted the ease of management of the tank. Reservations in the frontal part made the machine invulnerable to the German 60-mm gun, which was supposed to arm the Maus, and could also protect the crew from shelling with its own 128-mm C-130 gun. The use of a special loading mechanism made it possible to bring the rate of fire to 70-6 per minute. For his age, the tank was revolutionary in terms of characteristics; there was simply no such thing in the world at that moment.
Following the results of the tests, the commission concluded: EC-7 meets the specified specifications. It was still built 4 prototype, slightly different from each other, as the project is constantly being finalized. In the autumn of 1948, the prototype No. 3 entered for testing at NIBT Polygon. The talk was about building the first batch of 15 combat vehicles, then in 1949, the order was increased to 50 tanks. However, these plans did not come to fruition. 18 February 1949 of the year on the basis of the Resolution of the Council of Ministers of the USSR No. 701-270ss the development and production in the country of tanks weighing more than 50 tons was stopped. This document put a cross not only on the EC-7, but also on another heavy tank EC-4. The main claim was the large weight of the tanks, which complicated their evacuation from the battlefield and transportation, not every road bridge could withstand their weight, and the number of suitable railway platforms was limited. It is worth noting that serial tanks with a battle mass of more than 50 tons are not built in our country so far.
Another heavy tank with the initials of the Soviet leader, the 7-tonne EC-60, which was created and launched into serial production at ChKZ in 4, played its negative role in the fate of the EC-1947 tank, where it was assembled upon completion of the EC-3 production. . The heavy tank IS-4, which at the time of its creation was the most powerful armor among all domestic tanks, was too low in cross-country capacity due to the too high specific ground pressure (0,9 kg / cm²) and was not the most reliable transmission. At the same time, its armament was no different from the EC-2 and EC-3 tanks. However, the greatest disadvantage of this combat vehicle was a large mass. Some believe that the EC-4 in some way discredited the idea of creating tanks weighing more than 60 tons, so for the heavier EC-7, the military initially had some skepticism. It is worth noting that the attempt to provide the tank with the highest level of protection brought the combat weight of the EC-7 to record 68 tons, instead of the planned 65 tons.
Another possible explanation for the abandonment of the mass production of the heavy tank EC-7 was just common sense and pragmatism. The concept of increasing the role of tanks in a possible nuclear missile war, which was emerging at that time, required the country to deploy large tank formations in advance, and therefore to release the maximum possible number of armored vehicles in peace years. It was believed that in the first two weeks of the future hypothetical conflict, ground forces would lose up to 40 percent of their tanks. In such a situation, the adoption of a heavy tank, the EC-7, which had dubious prospects for mass production, was declared inadmissible by the military leadership. The LKZ simply did not have sufficient capacity at that time, and the launch of production at ChKZ was almost unreal.
One of the prototypes of the EC-7 tank, the only 1948 tank of the year built, can be seen in the collection of the Museum of Armored armament and equipment in Kubinka. It can be said without exaggeration that the EC-7 was the best heavy tank ever built. stories tank building, he would not get lost on the background of modern MBT. However, its development was not in vain. Many ideas implemented in the EC-7, were then used to create the tank "Object 730", adopted under the designation T-10 (EC-8).
Baryatinsky M., Kolomiets M., Koschavtsev A. Soviet heavy post-war tanks // Arm collector. - 1996. - No. 3 (6).
Materials from open sources.