Experienced and experimental heavy tanks of the USSR
At a time when the IS-2 heavy tank had not yet come to its final form, and it was being debugged in a series, silhouettes of new heavy tanks appeared on the drawing boards, but not all of them would have a chance to be embodied in metal.
Wooden model IS-6.
In June 1944, the design bureau of plant No. 100 presented to the GBTU a draft design of a heavy tank IS-6, a feature of which was the use of an electric transmission. Consideration of the project did not reveal any advantage over the tanks "Object 701" and "Object 703", but its superiority over the IS-122 was obvious. Clarification of the main tactical and technical characteristics provided, first of all, limiting the mass of the tank to 50 tons and invulnerability from frontal fire with 88mm sub-caliber projectiles from a distance of 500 meters or more. It was also decided to build two prototypes - "Object 252" with mechanical transmission and "Object 253" with electromechanical, as it was originally intended. The tanks were armed with a projected 122mm D-30 cannon with a high muzzle velocity. The body armor in the frontal parts had a thickness of 100mm (top sheet) and 120mm (bottom sheet), the tower was cast with a wall thickness of up to 150mm. The shelling of 88mm and 105mm German guns confirmed the durability even higher than required, and did not break through from a distance of 50 meters into the upper armor plate, the lower 120mm armor plate was struck only from a short distance.
Tank "Object 252"
The Object 252 was the first to go to factory tests, and during the period from November 8 to November 27, 1944, it underwent sea trials on the Sverdlovsk-Chelyabinsk route. The transmission worked generally satisfactorily (there was overheating of the gearbox when driving in top gear and excessive efforts to turn off the main clutch, reaching 60-65 kgf.), The tank was easy to control and showed good average speed values. However, the undercarriage with large-diameter rollers and without supporting rollers had an unacceptably small resource - the rollers were deformed after 200-250 kilometers. The development of the chassis and the gun was carried out on a converted IS-122 tank, loaded up to 50 tons. The result of the tests was the revision of the road wheels, designed by the design bureau of plant No. 100 anew, but it turned out more difficult with the gun - on November 17, after numerous failures and alterations, it finally failed and required factory repair.
Electric transmission diagram of the IS-6 tank.
In the meantime, the second prototype of the IS-6 tank, "Object 253", with an electromechanical transmission, but with a chassis from the serial IS-2, with road wheels and supporting rollers, came out for testing. Theoretically, this type of transmission promised great benefits - improved traction characteristics at low revs, better controllability of the tank. But due to the large mass of units, the miracle did not happen. Unfortunately, on the very first trip, when overcoming a snow-covered field, a fire occurred in the engine compartment, and the extinguishing equipment did not work properly (although it did detect a flame). The tank burned out and could not be restored.
Soon after the accident, all work on the IS-6 project was curtailed.
Tanks "Object 252" and "Object 253" (the differences in the chassis are clearly visible).
Using all the experience gained in the design, serial production and combat use of heavy tanks, as well as the results of work on prototypes, plant No. 100 at the end of 1944 began the preliminary design of the next heavy tank. After the allocation of funds (not without the personal intervention of L. Beria, to whom Zh. Kotin turned - since the People's Commissariat of the Tank Industry had already exhausted all the planned funds for other projects), design work on the topics "Object 257", "Object 258" and "Object 259 "and their final analysis led to the development of tactical and technical requirements, which formed the basis of a completely new project -" Object 260 ".
Drawings of the first version of the "Object 260".
Working drawings of this machine, indexed IS-7, were ready by the beginning of September 1945. The hull shape was the same as the IS-3, with a characteristic triangular nose, but the tank was larger - about 65 tons of curb weight. The power plant in the form of two diesel engines V-11 or V-16, which worked on generators of an electromechanical transmission. The alleged armament of a 122mm high-power gun was not manufactured, and as an alternative, a 130mm S-26 gun was designed, with ballistics from the B-13 naval gun.
Wooden model of the IS-7 tank.
After the construction of a full-size model and the work of the model commission, it was decided to make changes to the project and build two prototypes. The first of them was completed in September 1946 and by the end of the year passed up to 1000 kilometers of sea trials. The main headache was the power plant - due to the lack of an engine of the required power, it was supposed to use a pair of V-16 diesels or a high-power engine developed by plant No. 800. However, the latter was never created, and the twin unit, after a long and fruitless refinement, was declared completely unusable. Then, together with the plant No. 500 of the Minaviaprom, the TD-30 diesel engine was created, based on the aircraft ACh-300. Despite the dampness of the structure and the need for fine-tuning, it was he who was installed on the first two samples of the tank. A simple manual gearbox with synchronizers transmitted torque to a two-stage planetary swing mechanism. The rear sprocket undercarriage consisted of large diameter media rollers on board, without support rollers. The independent torsion bar suspension with beam torsion bars and double-acting hydraulic shock absorbers has been thoroughly tested on production tanks. It is worth noting the use for the first time in domestic tank building of tracks with a rubber-metal hinge, double-acting hydraulic shock absorbers and a number of other innovations.
Drawings of the final version of Object 260.
In 1947, the Object 260 project underwent a number of significant changes, in particular, the hull was widened and the turret profile was changed. On the basis of the S-26 gun, a new S-70 was created with a barrel length of 54 caliber (which gave the 33.4 kilogram armor-piercing projectile an initial speed of 900 m / s). The composition of auxiliary weapons has significantly expanded - now it consisted of one 14.5mm KPVT and two 7.62mm RP-26 paired with a gun, one anti-aircraft KPVT on a remotely controlled turret carried on a long bar, a pair of RP-46 in the rear of the fenders (rigidly installed in armored boxes outside the tank for forward fire) and RP-46 pairs on the sides of the turret aft niche for backward firing.
The crew consisted of 5 people, stationed in addition to the driver in the turret. The commander sat to the right of the gun, the gunner to the left, and two loaders were in the back, right and left. Their work was facilitated by an electric charging mechanism, created according to the type of marine installations. The gunner received a stabilized sight, which made it possible to fire a gun only when the axis of the bore coincided with the line of sight. It was decided to use the M-50T marine diesel engine with a capacity of 1050 hp as a power plant. at 1850 rpm. The transmission has been replaced with a 3K-type gearshift and cornering mechanism. This allowed the 68-ton tank to reach a speed of 60 km / h! At the same time, thanks to the use of hydraulic sevroamplifiers, the control was distinguished by ease and obedience.
Four experimental tanks were built by the summer of 1948 and, after passing factory tests, were transferred to the state. One of the hulls was tested with a German 128mm gun and their own 130mm - both were unable to penetrate the frontal armor. During the tests, one of the tanks burned out after the ignition of the engine that had exhausted its resource. The order for an experimental batch of 50 tanks remained unfulfilled, and after the decision was made to limit the mass of heavy tanks to a limit of 50 tons, the fate of the project was finally decided.
Tank IS-7 on trial.
"Object 277".
In 1956, the GBTU of the Red Army developed the tactical and technical requirements for a heavy tank, which was supposed to replace the T-10. The design bureau of the Kirovsky plant in Leningrad began to create a tank, with extensive use of ideas and individual components from the IS-7 and T-10 tanks. Received the index "Object 277", the new tank was created according to the classic layout, its undercarriage consisted of eight support and four support rollers on board, suspension on beam torsion bars, with hydraulic shock absorbers on the first, second and eighth rollers. The hull was assembled from both rolled and cast parts - the sides were made of bent rolled armor plates, while the bow was a single casting. The tower was also cast, hemispherical in shape. A well-developed niche accommodated a mechanized ammo rack to facilitate the actions of the loader. The armament consisted of a 130mm M-65 gun, stabilized in two planes with the help of the Groza stabilizer, and a coaxial 14.5mm KPVT machine gun. Ammunition 26 separate loading shots and 250 rounds for a machine gun. The gunner had a TPD-2S stereoscopic rangefinder sight, the tank was equipped with a full set of night vision devices. The power plant was a 12-cylinder V-shaped diesel M-850, with a capacity of 1050 hp. at 1850 rpm. Transmission planetary, type "3K", made in the form of a single block of the mechanism for changing gears and turns. Unlike the transmission of the T-10 tank, the band brakes of the planetary turning mechanism were replaced with disc brakes. The crew consisted of 4 people, three of whom (commander, gunner and loader) were in the tower. With a mass of 55 tons, the tank showed a maximum speed of 55 km / h.
Object 277 in Kubinka.
Drawings of the Object 277 tank.
Two copies of Object 277 were produced, and shortly after testing began, work on it was discontinued. The tank compares favorably with the T-10 with more powerful weapons and a more advanced MSA, including a rangefinder, but the ammunition load was small. In general, "Object 277" was created on the basis of well-developed in a series of units and did not require long-term refinement.
Tank "Object 770" on trials
The second contestant was the tank of the Chelyabinsk Tractor Plant - "Object 770". Unlike Object 277, it was decided to design the tank from scratch, relying only on advanced solutions and using new units. A characteristic feature of the tank was a completely cast hull, the sides of which differed in both differentiated thickness and variable angle of inclination. A similar approach can be traced in the armor of the hull's forehead. The turret is also completely cast, with variable armor thickness reaching up to 290mm in the frontal parts. The armament and control system of the tank are completely similar to the "Object 277" - a 130mm M-65 gun and a coaxial 14.5mm KPVT machine gun, 26 rounds and 250 rounds of ammunition. Of interest is the power unit of the tank, made on the basis of a 10-cylinder diesel engine DTN-10, with a vertical arrangement of cylinder blocks, which was installed perpendicular to the longitudinal axis of the tank. The engine power was 1000 hp. at 2500 rpm. The transmission of the tank included a torque converter and a planetary gearbox, the parallel connection of which made it possible to have one mechanical and two hydromechanical forward gears, and one mechanical reverse gear. The undercarriage included six large-diameter road wheels per side, without supporting rollers. The suspension of the rollers is hydropneumatic. The tank was distinguished by its ease of handling and good dynamic characteristics.
Tank "Object 770" on display at the Armored Museum in Kubinka.
Object 279
The most interesting of the projects submitted for the competition, without a doubt, can be considered a heavy tank "Object 279". This tank, unique in its design, was designed at the design bureau of the Leningrad Kirov plant, but L. S. Troyanov led the development. In defiance of the conservative Object 277, the car was created completely anew, and not only in terms of the units used, but also in concept. Cast hulls with differentiated armor, elliptical shapes have been encountered before, but in this vehicle the idea was taken to the absolute. Assembled from four cast parts, the body was covered around the entire perimeter with an anti-cumulative screen, which supplemented its contours to an elliptical shape (not only in plan, but also in vertical section). Thanks to the reduced armor volume to the limit, amounting to only 11, 47 m3, it was possible to achieve unprecedented values of the thickness of the armor both along the normal and reduced - the frontal armor of the hull reached 192 mm at large angles of inclination and turn, side armor up to 182 mm, at smaller angles. The cast turret of a flattened hemispherical shape had a circular armor of 305 mm, with the exception of the stern.
armoring scheme for the "Object 279" tank.
The armament was the same 130mm M-65 gun and 14.5mm KPVT machine gun, with 24 rounds of ammunition in a mechanized ammo rack with semi-automatic loading and 300 rounds for a machine gun. The combined efforts of the loader and the cassette semiautomatic loader provided a combat rate of fire of 5-7 rounds per minute. The MSA included a stereoscopic sight-rangefinder with independent stabilization of the field of view TPD-2S, a two-plane electro-hydraulic stabilizer "Groza" and a full set of night vision devices. The power plant of the tank was developed in two versions - a DG-1000 diesel with a capacity of 950 liters. with. at 2500 rpm or 2DG-8M with a capacity of 1000 liters. with. at 2400 rpm. Both engines are 4-stroke, 16-cylinder, H-shaped with horizontal cylinders (to reduce the height of the body). The tank's transmission was also distinguished by its unusual and innovative approach - a hydromechanical and planetary 3-speed gearbox, and the switching between the two top gears was automated.
But the most conspicuous part of the tank is by far its chassis, which featured four tracked propellers! The hull of the tank rested on two box-shaped structures, which were also fuel tanks, each of which, in turn, carried a pair of tracks. In relation to one propeller, the undercarriage consisted of six road wheels, three support rollers, a sloth and a drive sprocket. The suspension is individual, hydropneumatic, adjustable. Thus, the concept of clearance became only a formality, and the tank could overcome vertical obstacles without the threat of landing on their bottom. The specific pressure was also very small - only 0.6 kg / m2, which made it possible to overcome deep snow and swampy areas. The disadvantages of the chosen undercarriage were poor maneuverability and increased resistance to movement, especially on heavy soils. Maintainability left much to be desired, due to the high complexity of the design and the inaccessibility of the internal pair of tracks.
The prototype of the tank was built in 1959 and began to be tested, but it immediately became clear that such an expensive vehicle had no chance of mass production. The successor of the T-10 was to be one of two tanks "seven hundred and seventy" or "two hundred and seventy-seventh", but none of the contestants was never adopted.
Photographs of the Object 279 tank from the exposition of the Military-Historical Museum of the Armored Vehicle (BTVT), Kubinka.
Table of tactical and technical characteristics of tanks:
