ISU-152 - Soviet heavy self-propelled gun of the final period of the Great Patriotic War. In the name of the self-propelled gun, the abbreviation ISU means that the self-propelled gun was created on the basis of the new heavy tank IS. The addition of the letter "I" in the designation of the installation was required in order to distinguish the machine from the already existing self-propelled gun SU-152, created on the basis of the KV-1S tank. Index 152 designated the caliber of the gun used.
The development of a new heavy self-propelled gun by the design bureau of the experimental plant No. 100 was carried out in June-October 1943, and already on November 6, 1943, the new self-propelled gun was adopted by the Red Army. At the same time, the Chelyabinsk Kirovsky Plant (ChKZ) began its production, which lasted until 1946. Several cars of this brand in 1945 were also produced by the Leningrad Kirovsky Plant (LKZ). ACS ISU-152 was actively used at the final stage of the Great Patriotic War and took part in almost all major battles of this stage, playing an important role in the defeat of Nazi Germany and its European allies. In addition to the Red Army, the ISU-152 was in service with the armies of Czechoslovakia and Poland.
After the end of the war, the ISU-152 underwent modernization and were in service with the USSR army for a long time. Also, these self-propelled guns were exported to Egypt. The self-propelled guns transferred to Egypt took part in the Arab-Israeli armed conflicts in the Middle East. The ISU-152 self-propelled guns were removed from service by the Soviet army only in the mid-1970s. A small number of machines that survived the melting down can now be found in museums around the world; some of the machines are also installed on pedestals and serve as monuments. In total, until 1946, 3242 ISU-152 self-propelled guns were produced.
ISU-152
ACS ISU-122 belonged to the type of fully armored self-propelled guns with a front-mounted armored jacket. This machine was created on the basis of the ISU-152 ACS by replacing the ML-20S arr. 1937/43 for the 122-mm field gun A-19 mod. 1931/37 with a change in the movable armoring element of the gun. This self-propelled gun was born with the aim of increasing the anti-tank action of self-propelled guns at long firing ranges. The height of the line of fire of the ACS ISU-122 was 1790 mm. The crew of the vehicle consisted of 4 or 5 people, its placement was similar to the placement in a self-propelled gun armed with a 152-mm howitzer. In the event that the crew of the ACS consisted of 4 people, then the loader function was performed by the lock.
Installation ISU-122 was adopted by the Red Army on March 12, 1944. This self-propelled gun, like the ISU-152, was mass-produced in Chelyabinsk at the ChKZ plant. Serial production of self-propelled guns lasted from April 1944 to September 1945. Until June 1, 1945, 1435 ISU-122 self-propelled guns were assembled in Chelyabinsk, which were quite actively used on all fronts of the Great Patriotic War. In total, 1735 machines left the factory workshops during the serial production.
Design features of ISU-152
The ISU-152 self-propelled gun had the same layout as all other serial Soviet wartime self-propelled guns (with the exception of the SU-76). The fully armored self-propelled body was divided into 2 parts. The gun, the ammunition for it and the crew were in front in the armored wheelhouse, which combined the control compartment and the fighting compartment. The engine and transmission were located at the rear of the SPG.
The armored body of the ACS was manufactured by welding from rolled armor plates with a thickness of 90, 75, 60, 30 and 20 mm. The armor protection of the self-propelled gun was projectile, differentiated. The casemate armored plates were installed at rational angles of inclination. Compared to the previous SPG of the same purpose and class, the SU-152, the ISU-152 armored hull was slightly higher (since it did not have the same landing depth as that of the vehicles without the KV-1S) and more spacious space. armored jackets. The increase in internal volume was achieved by reducing the angles of inclination of the side and zygomatic armor plates. The associated insignificant decrease in protection was compensated by an increase in the thickness of the armor of these parts of the cabin. The increase in the volume of the felling had a positive effect on the working conditions of the ACS crew.
The ISU-152 self-propelled guns crew consisted of 5 people. Three crew members were to the left of the gun. Ahead was the driver's seat, immediately behind him was the gunner, and the loader was in the back. The self-propelled gun commander and the castle commander were located on the right side of the gun. The embarkation and disembarkation of the crew was carried out through a rectangular double-leaf hatch located at the junction of the roof and rear sheets of the armored jacket, as well as through a round hatch located to the right of the gun. Another round hatch to the left of the gun was used to bring out the extension of the panoramic sight and was not used for landing the crew. The SPG hull also had an emergency hatch located in the bottom.
All hatches that were used for embarkation / disembarkation of the crew, as well as the hatch of the artillery panorama, were equipped with Mk IV periscopes, which were used to monitor the situation on the battlefield (3 in total). The ACS driver-mechanic monitored the road using a triplex viewing device, which was covered from shrapnel with a special armored damper. This device was located in an armored cork hatch on the frontal armor plate of the ACS to the left of the gun. During marches and in calm conditions, this hatch-plug could be pushed forward, providing the driver with a better view from his workplace.
The main armament of the self-propelled guns was an ML-20S howitzer-gun of 152, 4 mm caliber, which was mounted in a special frame on the frontal armor plate of the wheelhouse and had vertical guidance angles in the range from -3 to +20 degrees. The horizontal guidance sector was equal to 20 degrees (10 in each direction). The height of the line of fire was 1, 8 m, the range of a direct shot at targets with a height of 2, 5-3 m, was 800-900 meters, the range of direct fire was 3, 8 km. The maximum firing range is 13 km. The shot could be fired using a mechanical or electrical trigger. The gun's ammunition consisted of 21 separate loading rounds.
From the beginning of 1945, large-caliber 12, 7-mm anti-aircraft machine guns DShK, equipped with a K-8T collimator sight, began to be installed on these ACS. The DShK was mounted on a special turret on the right round hatch, which was used by the vehicle commander. Machine gun ammunition was equal to 250 rounds. For self-defense, the crew could also use 2 PPS or PPSh submachine guns with 1491 rounds of ammunition, as well as 20 F-1 grenades.
ACS ISU-152 was equipped with a V-shaped four-stroke 12-cylinder V-2-IS diesel engine, which produced a maximum power of 520 hp. with. (382 kW). The diesel was equipped with a high-pressure NK-1 fuel pump with a fuel supply corrector and an RNK-1 all-mode regulator. A “Multicyclone” filter was used to clean the air entering the engine. Additionally, heating devices were mounted in the engine-transmission compartment of the self-propelled gun, which served to facilitate starting the engine in the cold season. Also, these devices could be used to heat the fighting compartment of the ACS in winter conditions. The self-propelled gun was equipped with three fuel tanks. Two of them were in the fighting compartment, one more in the MTO. Additionally, 4 external fuel tanks could be installed on the ACS, which were not associated with the engine fuel system.
ISU-122
Design features of ISU-122
The main difference between the ISU-122 self-propelled guns and the ISU-152 was the gun, otherwise these self-propelled guns were almost completely identical. The ISU-122 was armed with the A-19 cannon of the 1931/37 model. In May 1944, changes were made to the design of this gun, which violated their interchangeability with previously issued barrels. The modernized gun was named 122 mm self-propelled gun mod. 1931/1944). The device of the A-19 cannon largely repeated the ML-20S, both guns had a piston bolt, only the length of the A-19 barrel was significantly higher and amounted to 46.3 caliber. The A-19 differed from the ML-20S in a smaller caliber, increased by 730 mm. length, fewer grooves and no muzzle brake.
To aim the gun, a screw-type rotary mechanism and a sector-type lifting mechanism were used. The elevation angles were in the range from -3 to +22 degrees, and the elevation angles were 10 degrees in both directions. The direct fire range was 5 km, the maximum firing range was 14.3 km. The rate of fire of the gun is 2-3 rounds per minute.
Already in April 1944, the ISU-122S self-propelled gun was designed in the design bureau of plant number 100, which was a modernized version of the self-propelled gun. In June, the created sample was tested and already on August 22 was adopted by the Red Army. In the same month, the ACS went into mass production. ACS ISU-122S was produced at ChKZ in parallel with other self-propelled guns. The ISU-122S differed from the ISU-122 by the use of a new gun - D-25S mod. 1944, which had a muzzle brake and a wedge-shaped semi-automatic shutter. The barrel length of the gun was 48 calibers. Due to the use of the breech of the gun and compact recoil devices, it was possible to increase the rate of fire of the gun, which, with the well-coordinated work of the crew, increased to 6 rounds per minute. The direct fire range was 5 km, the maximum firing range increased to 15 km. The ammunition load of the gun, like that of the A-19 cannon, was 31 rounds. Externally, the ISU-122S differed from the ISU-122 with a new molded gun mask with a thickness of 120-150 mm. and the barrel.
ISU-122S
Combat use
Organizationally, ISU-152/122 were used as part of separate heavy self-propelled regiments (OTSAP). Each regiment was armed with 21 self-propelled guns, consisting of 4 batteries of 5 vehicles and one commander's self-propelled gun. Often the ISU was replaced in the SU-152 units or went to the formation of newly created units. Despite the officially established identical tactics for using the ISU-152 and ISU-122 self-propelled guns, they tried, if possible, not to mix them as part of one unit, although in practice there were a number of regiments in which the self-propelled guns were used together. In total, 53 OTSAPs were formed by the end of the war.
Heavy self-propelled guns were used to destroy long-term fortifications and field fortifications of the enemy, combat tanks at long distances, and support the advancing troops. Combat experience has shown that the ISU-152 is able to successfully cope with all these tasks, while a kind of division of labor between self-propelled guns was also revealed. The ISU-122 was more suitable for the destruction of enemy armored vehicles, and the ISU-152 for the fight against fortifications and assault actions. At the same time, the ISU-152 could fight any armored vehicles of the Wehrmacht. Her nicknames speak for themselves: the Soviet "St. John's wort" and the German "Dosenoffner" (can opener).
Solid armor allowed the self-propelled guns to approach at distances inaccessible to towed artillery and hit targets with direct fire. At the same time, ISUs had good maintainability and good survivability under the influence of enemy fire.
True, the weaknesses of the ISU-152 also came to light in the battles. The limited horizontal guidance angles made the vehicle vulnerable to flank attacks (for the sake of fairness, it should be noted that the Wehrmacht's self-propelled guns also suffered from this). The lower elevation angle of the gun (20 degrees versus 65 for the towed version of the howitzer) narrowed the possibility of maneuvering fire at long distances. Due to the use of separate loading shots, which had a large mass, the rate of fire suffered (up to 2 rounds per minute), which somewhat reduced the effectiveness of the fight against German armored vehicles, especially in close combat. And, finally, a transportable ammunition stock of 20 rounds, which was often insufficient in combat conditions. At the same time, loading ammunition into the self-propelled guns was a rather tedious operation that could take up to 40 minutes. It is worth noting that all these shortcomings were the reverse side of the advantages that the ISU-152 possessed. The high efficiency of self-propelled artillery fire was directly related to the use of separate-loading large-caliber shells.
ISU-122S during the assault on Konigsberg
The weaknesses possessed by a single self-propelled gun, experienced commanders tried to compensate for their correct use. During the repulse of tank attacks, the self-propelled guns were built in a fan to avoid flanking bypass. When firing from closed positions, ammunition for self-propelled guns was delivered in advance and at a time when some of the vehicles were firing, others were reloading, which ensured the continuity of artillery impact on the enemy.
The most effective ISU demonstrated during the assault on cities and fortified zones of the German defense. Especially here the ISU-152 stood out, whose 43-kg high-explosive projectile made the self-propelled gun the most terrible enemy for the entrenched enemy. A considerable part of the success during the assault on Konigsberg and Berlin lies precisely with the Soviet self-propelled guns who fought in these vehicles. The ISU-152 made their last volleys during World War II on the other side of Eurasia, during the offensive operation of the Red Army against the Japanese Kwantung Army.
Performance characteristics: ISU-122/152
Weight: 46 tons.
Dimensions:
Length 9, 85/9, 05 m, width 3, 07 m, height 2, 48 m.
Crew: 5 people.
Reservation: from 20 to 90 mm.
Armament: 122-mm gun A-19S / 152-mm howitzer-gun ML-20S, 12, 7-mm machine gun DShK
Ammunition: 30/21 shells, 250 rounds for the machine gun
Engine: twelve-cylinder V-shaped diesel engine V-2-IS with a capacity of 520 hp
Maximum speed: on the highway - 35 km / h, on rough terrain - 15 km / h.
Progress in store: on the highway - 220 km, on rough terrain - 140 km.
