In the initial period of the war, Soviet tanks of new types had an advantage in protection and firepower. However, the positive qualities of the KV and T-34 were largely devalued by the unreliable engine-transmission unit, poor sights and observation devices. Nevertheless, despite serious design and manufacturing defects, with proper preparation, our tankers often emerged victorious in battles with the German Pz. Kpfw. III, PzKpfw. IV and Pz. Kpfw. 38 (t).
However, already in the first half of 1943, reports began to arrive from the front, which spoke of the loss of the qualitative superiority of Soviet tanks over enemy armored vehicles. It was not even about the heavy "Tigers", which, due to their small numbers, did not have a decisive influence on the course of hostilities. Back in March 1942, the production of the Pz. KpfW. IV Ausf. F2 medium tank began, armed with a 75 mm cannon 7, 5 cm Kw. K.40 L / 43 and protected in frontal projection by 50 mm armor. Armor-piercing blunt-headed projectile Pzgr 39 weighing 6, 8 kg, leaving the barrel with an initial speed of 750 m / s, at a distance of 1000 m along the normal could penetrate 78-mm armor.
The Pz. KpfW. IV Ausf. G medium tank, which had 80mm frontal armor, was armed with the Kw. K.40 L / 48 cannon in the spring of 1943. The armor-piercing 75 mm shell of the Kw. K.40 L / 48 gun had an initial velocity of 790 m / s and was capable of penetrating 85 mm armor at 1000 m. In addition to tanks, the StuG. III and StuG. IV self-propelled guns received the long-barreled 75-mm guns. Soviet 76, 2-mm guns F-32, F-34 and ZIS-5, installed on KV and T-34 tanks, when firing with an armor-piercing blunt-headed projectile BR-350B could penetrate the frontal armor of the German "Quartet" released in 1943, at a distance of 300 m.
Thus, the modernized German medium tanks Pz. KpfW. IV and tank destroyers based on them by the middle of 1943 had a significant advantage over Soviet tanks in terms of armor penetration of their guns, and approached heavy tanks in terms of frontal protection. In the second half of 1942, the anti-tank units of the Wehrmacht began to receive towed 75-mm cannons 7, 5 cm Pak 40 in noticeable volumes, and in the ammunition load of 50-mm guns 5 cm Pak. 38 introduced the PzGr 40 sub-caliber projectile. Soviet heavy and medium tanks began to suffer heavy losses.
To compensate for the emerging qualitative superiority of the enemy in tanks, simultaneously with other measures, the SU-85 anti-tank self-propelled artillery mount was put into production in August 1943. Due to the urgent need for tank destroyers, this machine supplanted the SU-122 SAU at the production facilities of the Ural Heavy Machine Building Plant (UZTM) in Sverdlovsk. Having much in common with the SU-122, armed with an M-30S 122-mm howitzer, the SU-85 self-propelled gun had a pronounced anti-tank orientation.
The ACS crew consisted of 4 people. At the same time, the control compartment and the fighting compartment were combined. Based on the experience of the combat use of Soviet tanks and self-propelled guns, when creating the SU-85, special attention was paid to ensuring the proper level of visibility and command control. On the right, on the roof of the wheelhouse, there was a commander's cupola without an access hatch, which was used by the commander of the self-propelled guns to observe the terrain and adjust the fire.
The tank destroyer SU-85 was equipped with an 85-mm D-5S gun with the ballistics of the 53-K anti-aircraft gun. The barrel length of the D-5S gun was 48.8 caliber, the direct fire range reached 3.8 km. The maximum firing range of a fragmentation grenade is 12, 7 km. The vertical guidance angles were from −5 ° to + 25 °, the horizontal firing sector was ± 10 °. Combat rate of fire - 5-6 rds / min, maximum - up to 8 rds / min. In addition to fragmentation shells, the ammunition load of 48 unitary rounds included armor-piercing caliber: 53-BR-365 (blunt-headed) and BR-365K (sharp-headed) weighing 9.2 kg, as well as a sub-caliber reel-type 53-BR-365P weighing 5 kg. According to reference data, the 53-BR-365 armor-piercing projectile with an initial speed of 792 m / s at a distance of 1000 m along the normal could penetrate a 102-mm armor plate. A sub-caliber projectile 53-BR-365P with an initial speed of 1050 m / s at a distance of 500 m, when hit at a right angle, pierced armor with a thickness of 140 mm. Subcaliber projectiles, which were on special account, were effective at relatively small distances, with an increase in the range, their armor penetration characteristics fell sharply. Thus, the SU-85 was able to effectively fight enemy medium tanks at distances of more than a kilometer, and at shorter distances to penetrate the frontal armor of heavy tanks.
In the process of mass production, the self-propelled gun was equipped with two non-interchangeable types of 85-mm guns: D-5S-85 and D-5S-85A. These options differed in the method of manufacturing the barrel and the design of the bolt, as well as in the mass of their swinging parts: 1230 kg for the D-5S-85 and 1370 kg for the D-5S-85A. Self-propelled units armed with D-5S-85A cannons were designated SU-85A.
In terms of mobility and security characteristics, the SU-85, which weighed 29.6 tons in the combat position, remained at the level of the SU-122. The maximum speed on the highway is 47 km / h. In store down the highway - 400 km. The thickness of the frontal armor, inclined at an angle of 50 °, was 45 mm. The thickness of the armor of the gun mantlet is 60 mm. Compared to the SU-122 self-propelled guns, armed with a short-barreled howitzer, the long table of the 85-mm gun demanded special attention from the SU-85 driver when driving in the city and wooded areas. Like other anti-tank self-propelled guns with a front-mounted fighting compartment, the SU-85 had a high risk of scooping up the earth with its barrel on a steep slope.
Since the SU-85 used components and assemblies that were well-developed on the T-34 tanks and the SU-122 self-propelled guns, the reliability of the vehicle was quite satisfactory. The self-propelled guns of the first batch had a number of manufacturing defects, but after the start of the mass assembly, there were no particular complaints about the quality of workmanship. In 1944, the front rollers were reinforced and thus the "sore" inherited from the SU-122 was eliminated.
SU-85s were sent to form medium self-propelled artillery regiments. According to the 1943 state, the SAP had 4 batteries, 4 SU-85s each. The control platoon had 1 T-34 tank and 1 light armored car BA-64. In February 1944, all regiments were transferred to a new state. According to the new state, the SAP consisted of 21 vehicles: 4 batteries, 5 units each and 1 vehicle of the regiment commander. In addition, the regiment received a company of machine gunners and a platoon of sappers. SAP was introduced into the tank, mechanized, cavalry corps and served as a fire reinforcement of the compound. Self-propelled guns were also used as part of anti-tank artillery fighter brigades as a mobile reserve.
The SU-85 self-propelled artillery mounts received a positive assessment among the troops. They entered the battle in the fall of 1943 and performed well in the battles for the Left-Bank Ukraine. But in fairness it should be said that the tank destroyer SU-85 was at least six months late. The use of these machines in the Battle of Kursk could have a serious impact on the course of hostilities.
As for the anti-tank capabilities of the SPG, a lot depended on the qualifications and coordinated actions of the crew. The sector of horizontal aiming of the gun was small, in the process of aiming the installation at the target, the driver was directly involved. Working conditions in the fighting compartment of the SU-85 were better than in the turret of the T-34-85 tank, which was also armed with an 85-mm cannon. The presence of a more spacious wheelhouse and convenient access to the ammunition rack had a positive effect on the practical rate of fire and accuracy of firing. At the same time, self-propelled gun crews complained that long-term shooting at the maximum rate was difficult due to the excessive gas content of the fighting compartment.
By the standards of the second half of 1943, the 45-mm armor of the SU-85's hull and wheelhouse no longer provided adequate protection against the enemy's 75-mm tank guns. In a duel situation with the German Pz. KpfW. IV Ausf. G at a distance of up to 1500 m, the opponents confidently pierced the frontal armor of the enemy's corps. However, under equal conditions, it was more difficult to get into a more squat self-propelled gun than into a tank. As for the confrontation with the "Tigers" and "Panthers", in this case, the crew of the Soviet 85-mm self-propelled gun had a chance of success when operating from an ambush. In the course of real clashes with German heavy tanks, it was found that the 85-mm gun penetrates the frontal armor of the Tiger tank from a distance of 600-800 m, and its side - from 1000-1200 m. Thus, the SU-85 self-propelled artillery mount was is able to successfully fight against medium German tanks Pz. KpfW. IV of all modifications and self-propelled guns based on them. The destruction of the PzKpfw. V and Pz. Kpfw. VI tanks was also possible, but with the right tactics.
The level of losses in the SAP equipped with the SU-85 directly depended on the tactical competence of the command. Often attached to rifle units to enhance the anti-tank capabilities of self-propelled guns, infantry commanders used them as line tanks, throwing them into frontal attacks on well-fortified German defenses.
After the SAPs equipped with SU-85s suffered heavy losses in the late autumn of 1944, the Headquarters prepared orders prohibiting the use of SPGs in the role of tanks. In addition, it was forbidden to use self-propelled artillery regiments, which were part of the anti-tank brigades, to escort tanks and infantry in isolation from the rest of the brigade. These regiments were supposed to serve as an anti-tank reserve in case of a breakthrough by enemy tanks.
A typical example of the successful use of self-propelled guns as part of such a reserve was the actions of the 1021st SAP of the 14th anti-tank brigade during the Shauliai offensive operation in July 1944 in the area of the village of Devindoni. By the decision of the army commander, the regiment was concentrated in the tank-hazardous direction behind the battle formations of the 747th anti-tank artillery regiment (57-mm ZIS-2 cannon). A large group of German tanks of up to 100 vehicles, accompanied by motorized infantry in armored personnel carriers, launched a counterattack. After a stubborn battle, enemy tanks broke through the battle formations of our forward units. To prevent further advance of the Germans, self-propelled guns SU-85 took up firing positions in ambushes on the path of movement of enemy tanks. Having allowed the tanks to reach a distance of up to 500 m, the self-propelled guns, together with field artillery guns, attacked them with sudden fire, destroyed and knocked out 19 vehicles, and the rest were forced to stop and return to their original position.
Along with positive reviews from the active army, the designers also received information about the need to improve the ACS. So, the commander of the 7th Mechanized Corps, Colonel Katkov, evaluating the vehicle, said:
The SU-85 self-propelled gun is currently the most effective means of dealing with enemy heavy tanks. With cross-country ability and maneuverability, not inferior to the T-34 tank, and with an 85-mm cannon, the self-propelled gun showed itself well in combat. But, using the fire and armor of their Tiger, Panther and Ferdinand self-propelled tanks, the enemy imposes modern combat at long distances - 1500-2000 m. In these conditions, the fire power and frontal protection of the SU-85 are no longer sufficient. It is required to strengthen the frontal armor of the self-propelled gun and, most importantly, equip it with a cannon with increased armor-piercing power, capable of hitting heavy Tiger-type tanks from a distance of at least 1500 m.
It became obvious that for a confident fight against all enemy tanks at a distance of more than 1000 m, a new SPG was required, equipped with a more powerful weapon, and having better protection in the frontal projection.
During the final phase of the war, German tanks were mainly used as a mobile anti-tank reserve, and the Soviet front line was rarely attacked. In this regard, the SU-85 began to be used to provide direct artillery support to advancing tanks and infantry. If in terms of field engineering structures and enemy manpower, the effect of an 85-mm 53-O-365 fragmentation projectile weighing 9.54 kg was satisfactory, then its power was often not enough to destroy long-term firing points. The effect of using the SU-85 in assault groups was noticeably lower than that of the SU-122 or heavy self-propelled guns. So, in October 1944, when the troops of the 3rd Belorussian Front broke through the defensive line of the Germans on the river. In Narva, some assault groups, having in their composition only the SU-85, could not complete the tasks of destroying the pillboxes, since the high-explosive effect of 85-mm shells was insufficient. This problem was solved as a result of an increase in the production of heavy self-propelled guns with 122-152-mm guns, as well as after the arrival of a new SU-100 installation with a much more powerful high-explosive fragmentation projectile than that of the SU-85.
ACS SU-85 was in serial production for exactly one year. During this period, military representatives received 2335 vehicles. Self-propelled units of this type actively fought until the end of hostilities. In the next post-war decade, all SU-85s were decommissioned or converted into tractors. This was due to the fact that there were a large number of T-34-85 tanks and SU-100 self-propelled guns.
