Decree of the State Defense Committee No. 4043ss of September 4, 1943 ordered the Experimental Plant No. 100 in Chelyabinsk, together with the technical department of the Main Armored Directorate of the Red Army, to design, manufacture and test the IS-152 self-propelled gun based on the IS tank until November 1, 1943. Its immediate predecessor is the SU-152 (KB-14) self-propelled gun based on the KV-1s tank.
The SU-152 self-propelled gun, which entered service on February 14, 1943, was in serial production until early 1944. The appearance of these machines in the battle at the Kursk Bulge was an unpleasant surprise for the Germans. A massive 152-mm armor-piercing projectile (48, 8 kg), fired from a direct shot distance of 700-750 m, pulled the turret off the Tiger. It was then that the heavy artillery self-propelled guns received the respectful nickname "St. John's wort" from the soldiers.
It goes without saying that the military wanted to have a similar self-propelled gun based on a new heavy tank, especially since the KV-1s was withdrawn from production.
Soviet experimental self-propelled gun ISU-152-1 (ISU-152BM with 152-mm cannon BL-8 / OBM-43, produced in a single copy) in the courtyard of plant No. 100 in Chelyabinsk
The layout of the IS-152 self-propelled guns (object 241), later called the ISU-152, did not differ in fundamental innovations. The armored wheelhouse, made of rolled sheets, was installed in the front of the hull, combining the control compartment and the combat compartment into one volume. Its frontal armor was thicker than that of the SU-152: 60–90 mm versus 60–75.
The howitzer-gun ML-20S of 152 mm caliber was mounted in a cast frame, which played the role of the upper machine tool, and was protected by a cast armor mask borrowed from the SU-152. The swinging part of the self-propelled howitzer-gun had minor differences compared to the field one: a folding tray was installed to facilitate loading and a flap with a trigger mechanism, the handles of the flywheels of the lifting and turning mechanisms were at the gunner's left in the direction of the machine, the trunnions were moved forward for natural balancing.
The ammunition load consisted of 20 separate loading rounds, half of which were BR-545 armor-piercing tracer shells weighing 48, 78 kg, and half of them were OF-545 high-explosive fragmentation cannon grenades weighing 43, 56 kg. For direct fire, the ST-10 telescopic sight was used, for firing from closed positions - a panoramic sight with an independent or semi-independent line of sight from the ML-20 field howitzer-gun. The maximum elevation angle of the gun was + 20 °, declination -3 °. At a distance of 1000 m, an armor-piercing projectile pierced 123-mm armor.
ISU-152 projections, 1944
On some of the vehicles on the anti-aircraft turret of the commander's hatch, a 12, 7-mm DShK machine gun of the 1938 model was installed.
The power plant and transmission were borrowed from the IS-2 tank and included a 12-cylinder four-stroke compressorless liquid-cooled diesel engine V-2IS (V-2-10) with a capacity of 520 hp. at 2000 rpm., multi-plate main clutch of dry friction (steel on ferrodo), 4-way eight-speed gearbox with a range multiplier, two-stage planetary swing mechanisms with locking clutches and two-stage final drives with a planetary row.
The chassis of the ACS, applied to one side, consisted of six twin cast road wheels with a diameter of 550 mm and three support rollers. The rear drive wheels had two removable toothed rims with 14 teeth each. Idler wheels - cast, with a crank mechanism for tensioning the tracks.
Assembling ACS ISU-152 at a Soviet plant. The ML-20S howitzer-gun, 152, 4 mm, is mounted in a frame on an armored plate, which will then be installed in the armored conning tower of a combat vehicle
Suspension - individual torsion bar.
Caterpillars are steel, fine-link, each of 86 single-ridged tracks. Stamped tracks, 650 mm wide and 162 mm pitch. The gearing is pinned.
The combat weight of the ISU-152 was 46 tons.
The maximum speed reached 35 km / h, the cruising range was 220 km. The machines were equipped with YR or 10RK radio stations and an intercom TPU-4-bisF.
The crew consisted of five people: commander, gunner, loader, lock and driver.
Already at the beginning of 1944, the release of the ISU-152 was constrained by the lack of ML-20 guns. To get out of this situation, at the artillery plant No. 9 in Sverdlovsk, the barrel of the 122-mm corps gun A-19 was placed on the cradle of the ML-20S gun and as a result they received a heavy artillery self-propelled gun ISU-122 (object 242), which, due to the higher initial speed of the armor-piercing shell - 781 m / s - was an even more effective anti-tank weapon than the ISU-152. The ammunition capacity of the vehicle increased to 30 rounds.
A Soviet soldier shoots at the range from a large-caliber anti-aircraft 12, 7-mm machine gun DShK installed on the ISU-152 self-propelled guns
Soviet self-propelled guns ISU-122 on the march. 1st Ukrainian Front, 1945
From the second half of 1944, on some ISU-122, the D-25S cannon with a semi-automatic wedge gate and a muzzle brake began to be installed. These vehicles received the designation ISU-122-2 (object 249) or ISU-122S. They were distinguished by the design of recoil devices, a cradle and a number of other elements, in particular, a new molded mask with a thickness of 120–150 mm. The gun sights are telescopic TSh-17 and Hertz panorama. The convenient location of the crew in the fighting compartment and the semi-automatic gun contributed to an increase in the rate of fire to 3-4 rds / min, compared to 2 rds / min on the IS-2 tank and ISU-122 self-propelled guns.
From 1944 to 1947, 2,790 self-propelled guns ISU-152, 1735 - ISU-122 and 675 - ISU-122S were manufactured. Thus, the total production of heavy artillery self-propelled guns - 5200 units - exceeded the number of heavy IS tanks manufactured - 4499 units. It should be noted that, as in the case of the IS-2, the Leningrad Kirovsky Plant was supposed to join the production of self-propelled guns on its basis. Until May 9, 1945, the first five ISU-152s were assembled there, and by the end of the year - another hundred. In 1946 and 1947, the production of the ISU-152 was carried out only at the LKZ.
Since the spring of 1944, the SU-152 heavy self-propelled artillery regiments were rearmed with the ISU-152 and ISU-122 installations. They were transferred to new states and all were given the rank of guards. In total, by the end of the war, 56 such regiments were formed, each containing 21 ISU-152 or ISU-122 vehicles (some of these regiments had a mixed composition of vehicles). In March 1945, the 66th Guards Heavy Self-Propelled Artillery Brigade of a three-regimental composition was formed (1804 people, 65 ISU-122, ZSU-76).
Soviet self-propelled guns ISU-122S is fighting in Konigsberg. 3rd Belorussian Front, April 1945
Soviet self-propelled guns ISU-152 in original winter camouflage with a landing party on armor
Heavy self-propelled artillery regiments attached to tank and rifle units and formations were primarily used to support infantry and tanks in the offensive. Following in their battle formations, self-propelled guns destroyed enemy firing points and provided infantry and tanks with a successful advance. In this phase of the offensive, self-propelled guns became one of the main means of repelling tank counterattacks. In some cases, they had to move forward in the battle formations of their troops and take the blow, thereby ensuring the freedom of maneuver of the supported tanks.
So, for example, on January 15, 1945 in East Prussia, in the Borove region, the Germans, up to one regiment of motorized infantry with the support of tanks and self-propelled guns, counterattacked the battle formations of our advancing infantry, with which the 390th Guards Self-Propelled Artillery Regiment operated. The infantry, under pressure from superior enemy forces, retreated behind the combat formations of the self-propelled gunners, who met the German blow with concentrated fire and covered the supported units. The counterattack was repulsed, and the infantry again got the opportunity to continue their offensive.
Heavy SPGs were sometimes involved in artillery barrage. At the same time, the fire was conducted both with direct fire and from closed positions. In particular, on January 12, 1945, during the Sandomierz-Silesian operation, the 368th ISU-152 Guards Regiment of the 1st Ukrainian Front fired for 107 minutes at the enemy stronghold and four artillery and mortar batteries. Firing 980 shells, the regiment suppressed two mortar batteries, destroyed eight guns and up to one battalion of enemy soldiers and officers. It is interesting to note that additional ammunition was laid out in advance at firing positions, but first of all, the shells that were in combat vehicles were spent, otherwise the rate of fire would have been significantly reduced. For the subsequent replenishment of heavy self-propelled guns with shells, it took up to 40 minutes, so they stopped firing well before the start of the attack.
Soviet tankmen and infantrymen in ISU-152 self-propelled guns. The album is signed: "Our lads on the ACS are on the front lines."
The heavy self-propelled guns were used very effectively against enemy tanks. For example, in the Berlin operation on April 19, the 360th Guards Heavy Self-Propelled Artillery Regiment supported the offensive of the 388th Infantry Division. Parts of the division captured one of the groves east of Lichtenberg, where they were entrenched. The next day, the enemy, with a force of up to one infantry regiment, supported by 15 tanks, began to counterattack. While repelling attacks during the day, 10 German tanks and up to 300 soldiers and officers were destroyed by the fire of heavy self-propelled guns.
In the battles on the Zemland Peninsula during the East Prussian operation, the 378th Guards Heavy Self-Propelled Artillery Regiment, while repelling counterattacks, successfully used the formation of the regiment's battle formation in a fan. This provided the regiment with shelling in a sector of 180 ° and more and facilitated the fight against enemy tanks attacking from different directions.
Units of the Soviet heavy self-propelled artillery regiment at the crossing of the Spree river. Right ACS ISU-152
One of the ISU-152 batteries, having built its battle formation in a fan on a front with a length of 250 m, successfully repelled a counterattack of 30 enemy tanks on April 7, 1945, knocking out six of them. The battery did not suffer losses. Only two vehicles received minor damage to the chassis.
Back in December 1943, given that in the future the enemy might have new tanks with more powerful armor, the State Defense Committee ordered by a special decree to design and manufacture by April 1944 self-propelled artillery mounts with high-powered guns:
• with a 122-mm cannon with an initial velocity of 1000 m / s and a projectile mass of 25 kg;
• with a 130-mm cannon with an initial velocity of 900 m / s and a projectile mass of 33.4 kg;
• with a 152-mm cannon with an initial velocity of 880 m / s and a projectile mass of 43.5 kg.
All these guns pierced 200 mm thick armor at a distance of 1500–2000 m.
In the course of the implementation of this decree, self-propelled guns were created and in 1944-1945 tested: ISU-122-1 (object 243) with a 122-mm cannon BL-9, ISU-122-3 (object 251) with a 122-mm cannon S- 26-1, ISU-130 (object 250) with a 130-mm S-26 cannon; ISU-152-1 (object 246) with 152-mm cannon BL-8 and ISU-152-2 (object 247) with 152-mm cannon BL-10.
ISU-152 crew on vacation. Germany, 1945
The S-26 and S-26-1 cannons were designed at TsAKB under the leadership of V. Grabin, while the S-26-1 differed from the S-26 only in the caliber of the pipe. The S-26 cannon of 130 mm caliber had ballistics and ammunition from the B-13 naval gun, but had a number of fundamental structural differences, since it was equipped with a muzzle brake, a horizontal wedge gate, etc. Self-propelled guns ISU-130 and ISU-122-1 were manufactured at the plant No. 100, and they were tested from June 30 to August 4, 1945. Later, the tests continued, but both self-propelled guns were not accepted into service and were not launched into the series.
The BL-8, BL-9 and BL-10 guns were developed by OKB-172 (not to be confused with plant number 172), all of whose designers were prisoners. The first prototype of the BL-9 was manufactured in May 1944 at the plant number 172, and in June it was installed at the ISU-122-1. Polygon tests were carried out in September 1944, and state tests were carried out in May 1945. On the latter, when firing, the barrel ruptured due to metal defects. The BL-8 and BL-10 cannons of 15 mm caliber had ballistics that significantly exceeded the ballistics of the ML-20, and were tested in 1944.
Self-propelled guns with prototypes of guns were characterized by the same drawbacks as the rest of the ACS on the IS chassis: a large forward reach of the barrel, which reduced maneuverability in narrow aisles; small angles of horizontal guidance of the gun and the complexity of its guidance, which made it difficult to fire at moving targets; low combat rate of fire due to the relatively small size of the fighting compartment, the large mass of shots, separate-case loading and the presence of a piston bolt in a number of guns; poor visibility from cars; small ammunition and the difficulty of replenishing it during the battle.
At the same time, the good projectile resistance of the hull and cabin of these self-propelled guns, achieved through the installation of powerful armor plates at rational angles of inclination, made it possible to use them at a direct firing distance and effectively hit any targets.
Self-propelled artillery installations ISU-152 were in service with the Soviet Army until the end of the 70s, until the beginning of the arrival of the new generation of self-propelled guns in the troops. At the same time, the ISU-152 was modernized twice. The first time was in 1956, when the self-propelled guns received the designation ISU-152K. A commander's cupola with a TPKU device and seven TIP viewing blocks were installed on the roof of the cabin; the ML-20S howitzer-gun ammunition was increased to 30 rounds, which required a change in the location of the internal equipment of the fighting compartment and additional ammunition stowage; instead of the ST-10 sight, an improved PS-10 telescopic sight was installed. All machines were equipped with a DShKM anti-aircraft machine gun with 300 rounds of ammunition.
The ACS was equipped with a V-54K engine with a power of 520 hp. with an ejection cooling system. The capacity of the fuel tanks was increased to 1280 liters. The lubrication system has been improved, the design of the radiators has changed. In connection with the ejection cooling system of the engine, the fastening of the external fuel tanks was also changed.
The vehicles were equipped with 10-RTiTPU-47 radio stations.
The mass of the self-propelled gun increased to 47, 2 tons, but the dynamic characteristics remained the same. The power reserve increased 360 km.
The second version of the modernization was designated ISU-152M. The vehicle was equipped with modified units of the IS-2M tank, a DShKM anti-aircraft machine gun with 250 rounds of ammunition and night vision devices.
During the overhaul, the ISU-122 self-propelled guns were also subjected to some alterations. So, since 1958, regular radio stations and TPUs were replaced by the Granat and TPU R-120 radio stations.
In addition to the Soviet Army, ISU-152 and ISU-122 were in service with the Polish Army. As part of the 13th and 25th self-propelled artillery regiments, they took part in the final battles of 1945. Soon after the war, the Czechoslovak People's Army also received the ISU-152. In the early 60s, one regiment of the Egyptian army was also armed with the ISU-152.
