Anti-tank potential and post-war service of self-propelled artillery units SU-100
The best Soviet fighter tanks created during the Great Patriotic War was a self-propelled artillery SU-100 installation. Unfortunately, the production of this vehicle began too late, and it did not have a noticeable impact on the course of military operations on the Soviet-German front.
Although the vehicle was generally very good and had balanced characteristics, at first it had a number of shortcomings associated with the hasty launch into serial production. The main "teething problems" of the PT SAU SU-100 were cured in peacetime. Thanks to the successful combination of high modernization potential, high combat and service-operational characteristics, the life and combat career of combat vehicles of this type lasted a long time, and in addition to the Soviet Army, it was in service in more than 20 countries during the Cold War. In some countries, the SU-100 is still listed as a combat vehicle or is in storage.
Creation and production of tank destroyer SU-100
The first domestic mass-produced specialized anti-tank self-propelled artillery unit is the SU-85. This machine, built on the basis of the medium tank T-34, was quite consistent with its purpose. But in the second half of the war, the armor of the SU-85 no longer provided the necessary protection, and the 85-mm gun could confidently penetrate the frontal armor of heavy German tanks at a distance of no more than 800 m. In the active army, this self-propelled gun was generally assessed positively, but crews with real experience in destroying enemy armored vehicles wanted to fight on a better protected machine armed with a gun of increased power. There were also complaints about the habitability conditions, observation devices and sights.
The results of firing captured heavy German tanks at the firing range demonstrated that in order to confidently penetrate the Tiger's frontal armor at a distance of more than 1000 m, the standard 85-mm 53-BR-365 caliber projectile weighing 9,2 kg must leave the barrel with an initial velocity of at least 1050 m/s. The same projectile fired from the barrel of the D-5S-85 gun mounted on the SU-85 had a velocity of 792 m/s. However, it was impossible to accelerate the existing projectile to such a velocity without significantly increasing the barrel length, its strength, and using an increased powder charge. Certain limitations were also imposed by the technological capabilities of our artillery factories. Another way to increase armor penetration could be the mass introduction of sub-caliber projectiles with improved characteristics. But when producing shells with hard-alloy cores, it was impossible to do without scarce metals: cobalt and tungsten, which were chronically lacking for smelting armor steel and manufacturing gun barrels. After analyzing all the factors, military and technical specialists decided to increase armor penetration by increasing the caliber. It was experimentally established that a gun with a caliber of at least 100 mm was required to reliably defeat heavy German tanks.
In mid-1941, a design team led by V.G. Grabin created the 107-mm ZIS-6 tank gun. At a distance of 1000 m, an armor-piercing projectile weighing 17 kg, leaving the barrel at a speed of 830 m/s when hitting at an angle of 60°, penetrated 110 mm of armor. By September 1941, the ZIS-6 gun was ready for serial production, but due to the refusal to produce the KV-3 and KV-4 tanks, this artillery system was not in demand. In terms of armor penetration, the ZIS-6 fully met the requirements for installation on the new tank destroyer, but this gun, like the divisional 107-mm M-60, had separate-case loading, which limited the practical rate of fire.
Having considered all the options, GRAU recommended arming the new anti-tank self-propelled gun with a 100-mm gun using unitary rounds of the 100-mm naval universal gun B-34. The naval system initially had a unitary loading, and the 100-mm projectile accelerated to a higher speed than the 107-mm. The difference between the armor-piercing shells for the B-34 and ZIS-6 was less than two kilograms. However, making a 100-mm tank gun with acceptable weight and size characteristics turned out to be a difficult task, and only in early 1944, under the leadership of F. F. Petrov, based on the naval anti-aircraft gun D-10, the 100-mm gun D-10S was created, which was lighter than its competitors and could be placed on the chassis of the medium tank T-34 without significant changes and unnecessary increase in the weight of the vehicle.
When creating the new self-propelled gun SU-100, Uralmashzavod designers used the developments from the SU-85. The crew of the SU-100 did not change compared to the SU-85, but many significant improvements were made, of which the most externally noticeable was the commander's cupola, which had a hatch and protruded beyond the outlines of the armored cabin.
Prototype SU-100 and serial SU-85
The SU-100 was equipped with a V-2-34 diesel engine with a capacity of 500 hp, thanks to which the vehicle weighing 31,6 tons could accelerate to 50 km/h on the highway. The speed on a dirt road usually did not exceed 20-25 km/h. The capacity of the internal fuel tanks was 400 liters, which provided the vehicle with a cruising range on the highway of up to 310 km. The cruising range on rough terrain was 140 km.
The thickness of the upper frontal plate and the driver's hatch was 75 mm, with an inclination angle of 50 °, which provided protection from the most common German 75-mm Pak. 40 and Kw.K.40 L / 48 guns. The thickness of the side armor remained the same - 45 mm. The thickness of the gun mantlet is 100 mm. The thickness of the commander's cupola armor was increased to 90 mm. The weakened area was the driver's hatch, which somewhat reduced the armor protection in the frontal projection. Already during the fighting it became clear that in most cases the frontal armor withstood hits from German 75-mm towed guns, 75-mm tank guns installed on the "fours", as well as hits from 50-mm sub-caliber shells. 75mm armor-piercing shells left dents 25-35mm deep, and the cores of 50mm sub-caliber shells got stuck in the frontal armor, having penetrated 50-60mm.
The designers paid special attention to improving visibility, for which purpose a MK-IV periscope device appeared on the commander's hatch flap, and there were also viewing devices along the perimeter of the commander's cupola. A powerful fan provided the extraction of powder gases. The general design of the gun mount was similar to the SU-85, but the slope of the rear sheet of the cabin was abandoned and the left front fuel tank was removed, which increased the volume of the fighting compartment.
The 100 mm gun was mounted in the front plate of the cabin in a cast frame on double trunnions, allowing its aiming in the vertical plane within the range of -3 to +20 ° and in the horizontal ±8 °. When firing direct fire, aiming at the target was carried out using a telescopic hinged sight TSh-19, and from closed positions - using a Hertz panorama and a side level. During testing, a rate of fire of up to 8 rounds / min was obtained. The practical rate of fire of the gun was 4-6 rounds / min. Ammunition compared to the SU-85 was reduced by almost a third and amounted to 33 rounds.
The energy of the D-10S gun was quite sufficient to destroy any German armored vehicles. The BR-412 armor-piercing tracer projectile weighing 15,88 kg had an initial velocity of 897 m/s and at a distance of 1500 m penetrated 115 mm of armor at a normal angle. At a distance of 1000 m, when meeting at a right angle, a 100 mm projectile penetrated a 135 mm armor plate.
During the firing of captured tanks at the proving ground, it was established that the 100 mm cannon penetrates the frontal armor of the Tiger and Panther at a distance of up to 1500 meters. The side armor of the heaviest serial German tanks, which did not exceed 82 mm, as well as the frontal armor of the main mass-produced medium tanks Pz.Kpfw. IV and late self-propelled guns StuG. III/IV, was penetrated from a distance of 2000 meters or more. Certain problems were encountered with overcoming the armor protection of the Pz.Kpfw. VI Ausf. B tank and the small-scale Ferdinand and Jagdtiger self-propelled guns. At the same time, due to the deterioration of the quality of German armor, which, due to the lack of alloying additives, contained an increased percentage of carbon, was hard but brittle, hits by 100-mm shells from a distance of 500-1000 meters led to the formation of cracks, chips and destruction of welds. Thus, the D-10S gun at real combat distances could reliably defeat most German tanks and self-propelled guns when fired from any direction. There are also known cases when 100-mm fragmentation grenades, when firing at a range of up to 4000 m, knocked out German medium tanks Pz.Kpfw. IV. Apparently, we are talking about damage to the chassis during a close explosion of a powerful shell containing 1,46 kg of explosives. However, with a direct hit to the side, the relatively thin 30 mm side armor of the “four” could also be broken through.
Instead of perforated road wheel bandages, solid bandages with greater durability were used. Two smoke grenades were attached to the upper rear plate of the hull. Also on the roof of the cabin, to the right of the panoramic hatch, a cap appeared, on which a new gun stopper was attached in a traveling position.
The SU-100 was accepted into service on July 3, 1944 by GKO Resolution No. 6131. However, the production of self-propelled guns was delayed by a shortage of 100-mm D-10S guns and rounds for them. And in order not to slow down production, a transitional model with an 85-mm D-5S-85A gun, known as the SU-85M, was initially produced. This vehicle was produced from September to November 1944 and was a "hybrid" of the SU-100 chassis and SU-85A armament.
By July 1945, more than 2300 SU-100s had been built, and serial production in the USSR continued until 1948. A total of 3241 vehicles were manufactured at factories in Sverdlovsk and Omsk. Self-propelled guns built in 1946-1948 featured armored vehicle assembly technology, improved weld quality, and a number of technical innovations aimed at increasing reliability.
Combat use of the SU-100 at the final stage of the war
The first batch of 40 SU-100 units was handed over to military acceptance in September 1944.
The SU-100 self-propelled gun successfully passed frontline tests, but deliveries to combat self-propelled artillery regiments had to be postponed for several months due to the lack of mass production of 100-mm armor-piercing shells. Incidentally, the same problem was encountered during the combat use of BS-3 field guns. At first, their ammunition consisted only of unitary rounds with high-explosive fragmentation grenades.
Since the development of the BR-412B armor-piercing projectile in production dragged on until October 1944, the first self-propelled guns were sent to training centers. Only in November were regiments equipped with SU-100s formed and sent to the front. The SAP staffing table was the same as that of regiments with SU-85s. The regiment numbered 318 people and had 21 self-propelled guns (20 vehicles in 5 batteries and 1 self-propelled gun of the regiment commander).
At the end of the year, three self-propelled artillery brigades (SABR) were formed on the basis of separate tank brigades: the 207th Leningrad, 208th Dvinskaya and 209th. Each brigade had 65 SU-100 and 3 SU-76M. The main reasons for the formation of the SABR were the difficulties with the management and organization of supplies for the SAP, the number of which reached two hundred by the end of 1944.
The SU-100 entered combat en masse in January 1945 during the Budapest Offensive. By that time, the Red Army was already sufficiently equipped with anti-tank artillery, new T-34-85 and IS-2 tanks, and highly effective anti-tank self-propelled guns SU-85, ISU-122, and ISU-152. At first, the SU-100 self-propelled guns did not show themselves in any way at the front. In addition, a number of design and manufacturing defects initially hampered the normal operation of the new self-propelled guns. Some vehicles developed cracks in the welded seams of the hull, and parts of the artillery unit were destroyed during firing. Despite the fact that, based on the experience of operating the SU-122 and SU-85, the SU-100 road wheels were reinforced and improvements were made to the suspension design, increased wear of the front rollers was observed. Not only were the bandages destroyed, but cracks were also found in the disks. As a result, it was necessary to simultaneously supply the units with support rollers and develop a reinforced front support roller and balancer for it.
The new self-propelled guns proved themselves on January 11, when up to 100 German tanks, supported by infantry, launched a counterattack. That day, the 1453rd and 1821st SAPs burned 20 enemy tanks. The SU-100s were used most widely during the Balaton Operation on March 6-16, 1945, when they repelled counterattacks by the 6th SS Panzer Army. Three self-propelled artillery brigades and several separate self-propelled artillery regiments took part in the fierce battles. During the operation, the SU-100s played a significant role in repelling German tank attacks and proved themselves to be a highly effective means in the fight against German heavy armored vehicles, including the PzKpfw VI Ausf. B Tiger II heavy tanks. Following the operation, the SU-100s earned extremely high praise.
In the final stages of the war, German tanks rarely appeared on the battlefield, and SU-100 crews mainly used UOF-412 high-explosive fragmentation shells, which were significantly superior in destructive effect to the 85-mm UO-367 grenade and demonstrated good effectiveness against enemy field fortifications, manpower and lightly armored vehicles. Experiments showed that when a 100-mm UOF-412 exploded, about 500 large fragments were formed, which hit infantry lying down at a distance of 22 m along the front and 9 m in depth. Full-length targets were hit at a distance of 31 m along the front and 13 m in depth. The self-propelled gun, firing high-explosive fragmentation shells weighing 15,6 kg containing 1,46 kg of TNT, was a fairly powerful means of destroying field fortifications during offensive operations, having an advantage over the T-34-85 medium tanks and the SU-85 self-propelled guns.
Along with high anti-tank qualities, the ability of 100-mm guns to effectively destroy field fortifications and destroy manpower, it turned out that the SU-100 was more vulnerable to infantry anti-tank weapons than tanks. This was due to the fact that self-propelled guns initially did not have machine gun armament, and aiming the gun at close targets required turning the hull. Due to the fact that the barrel length of the D-10S gun exceeded 5 meters, maneuvering in rough wooded terrain and in the city was difficult. In order to reduce losses from infantry armed with panzerfausts, some of the vehicles were additionally equipped with light machine guns. When conducting combat operations in populated areas, it was recommended not to introduce the SU-100 into them if possible, and to use the ISU-152 and tanks to destroy fortifications within the city limits.
The SU-100 self-propelled guns suffered almost no losses from fire from counterattacking enemy tanks. The majority of the vehicles destroyed or damaged in offensive actions fell victim to fire from anti-tank and anti-aircraft guns set to direct fire, and also were blown up by mines. After the start of the Berlin Operation, the self-propelled guns took part in it. In urban combat, the self-propelled guns were attached to separate rifle units and subdivisions to reinforce them. If on the approaches to Berlin the percentage of irreparably destroyed vehicles was not large, and the majority of damaged SU-100s were returned to service, then after the entry of Soviet troops into the city, irreparable losses increased, and many vehicles burned as a result of being hit by cumulative grenades. Thus, in the 2nd Guards Tank Army as of the beginning of April there were 46 SU-100. From 16 to 21 April, 5 SU-100s were lost. By the end of the Berlin operation, the 2nd Guards Tank Army had irretrievably lost another 7 SU-100s, including 5 vehicles directly in the city.
Post-war production and modernization of the SU-100, as well as service in the Soviet Army and abroad
In the USSR, after the war, the SU-100 was not produced for long, which can be explained by the establishment of serial production of T-54 tanks, which were armed with a 100-mm D-10T cannon and were superior to self-propelled guns in terms of protection.
However, given that in the first post-war decade the Soviet leadership was not ready to supply T-54s abroad, and the power of the T-34-85 gun was not enough to reliably penetrate the armor of new American and British tanks, the need for the SU-100 in the armies of the Eastern Bloc remained.
In order to increase the anti-tank potential of the Warsaw Pact countries' armed forces and deliveries to "developing countries", licensed production of the SU-100 under the name SD-100 was established first in Prague and then at the Czechoslovakian enterprise ZJVS in Martin. At the SMZ locomotive plant (one of the Škoda concern's plants, located in Dubnice nad Váhom), they also made a licensed D-10S, which received the Czechoslovakian designation 100 mm SHK vz.44 S. The development of SU-100 production in Czechoslovakia was facilitated by the fact that since 1951, this country had been producing T-34-85 medium tanks.
The Czechoslovakian self-propelled gun had a number of external features that allowed it to be visually distinguished from the SU-100 built in the USSR. Also, the SD-100 hull stood out with more accurate welds and a virtually ideal surface of the armor plates. The external finish did not affect the combat qualities of the vehicles, but demonstrated the level of production culture.
A total of 1953 SD-1956s were built in Czechoslovakia between 770 and 100. Of this number, the Czechoslovak army received 460 units, the rest were delivered to Cuba, Syria and Egypt. The Cuban army used the self-propelled guns very effectively in repelling the counter-revolutionary invasion in the Bay of Pigs. Several self-propelled guns of this type have been installed in Cuban cities as monuments.
Syrian and Egyptian self-propelled guns took part in armed conflicts in 1956, 1967 and 1973. The Arabs abandoned quite a few serviceable SD-100s along with other armored vehicles on the battlefield.
In the tank regiments of the Czechoslovak People's Army, the share of SD-100s was one third of the total number of vehicles until 1960. T-34-85 tanks replaced by self-propelled guns were sent to storage. In the 1960s, after the start of T-54 deliveries, SD-100s began to go to storage bases and were actively offered to foreign buyers. Nevertheless, the active service of the SD-100 in Czechoslovakia continued until the end of the 1970s, these vehicles were in reserve until the mid-1990s.
The situation with the SU-100 was approximately the same in the Soviet Army. According to reference data, in November 1947, there were 2628 SPGs with a 100-mm gun in service.
Although the SU-100 had a number of shortcomings, was inferior to the T-54/55 tanks in terms of protection and had no advantages over them in terms of armament, the self-propelled guns were actively used until the early 1980s, and were finally written off in Russia in the early 1990s. Apparently, the last SU-100s in combat units were used in the Far East, which was due to the better cross-country ability of these machines on soft soils compared to the T-54, T-55 and T-62, a relatively weak tank fleet that China had. The SU-100s were also used during the introduction of a "limited contingent" into Afghanistan.
Despite the fact that the basic chassis of the SU-100 was outdated, and from the point of view of fire safety and crew survivability in the event of combat damage, the placement of fuel tanks in the fighting compartment was not optimal, the self-propelled guns were modernized and overhauled in the 1950s-1970s.
It took a long time to cope with the low durability of the front rollers. Despite the strengthening of the suspension springs, it was not possible to ensure the required guaranteed mileage of 3000 km. As of 1948, the guaranteed mileage of the SU-100 was 1000 km. In the post-war period, this problem was solved by installing chassis parts from the T-44M tank.
In the late 1950s and early 1960s, the MK-IV commander's observation device was replaced by the TPKU-2 binocular commander's panorama with coordinate and rangefinder scales, which had a five-fold increase and a field of view of 7,5° along the horizon, allowing targets to be identified at a distance of up to 3 km. During the modernization, the SU-100 was equipped with passive night vision devices BVN and TVN-2, which worked together with the FG-10 headlight equipped with an IR filter and the R-113 VHF radio station.
In the mid-1950s, a more effective armor-piercing projectile, the UBR-412D, was added to the ammunition set. This projectile weighs 15,88 kg and has an initial velocity of 887 m/s. At a distance of 1000 m, the UBR-412D is capable of penetrating 190 mm of armor at a normal angle. However, this was not enough to reliably counter the British Chieftain tanks, as well as the American M-48A2 and M-60. The 3BM8 subcaliber projectile weighing 5,7 kg, leaving the gun barrel at a velocity of 1415 m/s, could penetrate the armor of the M-48A2 from any direction, as well as the turrets of the Chieftain and M-60, but did not penetrate the upper frontal armor of these tanks. The cumulative non-rotating tracer projectile 3BK5 weighed 25,5 kg and had an initial velocity of 900 m/s at an angle of 60° from the normal at any distance, overcame homogeneous armor 180 mm thick, which made it possible to destroy all existing Western tanks at that time. The standard ammunition load of the modernized SU-100 consisted of 16 high-explosive fragmentation, 10 armor-piercing and 7 cumulative projectiles.
The modernized SU-100s differed externally from the original version in that they had external boxes for tools and accessories, as well as running wheels.
In the late 1970s, the 38th Research Institute of Armored Vehicles in Kubinka developed a radio control system for converting obsolete tanks into mobile targets capable of firing a single blank shot loaded into the gun. Beginning in 1981, the Borisov Tank Repair Plant converted 121 SU-100s into self-propelled targets, which took part in the major exercises "West-81", "West-83", "West-84" and "Autumn-88".
Abroad, in addition to the countries that were part of the Warsaw Pact, the SU-100 was operated in Algeria (until the early 1990s), Albania (until the mid-1990s), Angola (destroyed in combat or written off due to breakdowns in the late 1980s), Bulgaria (until 1993), China (until the early 1980s), the GDR (in storage until unification with the FRG), Hungary (in storage until the early 1990s), Iraq (in storage until 2003), Mongolia (until the late 1980s), Poland (until the mid-1980s), Romania (in storage until 2015), and Yugoslavia (until the late 1990s).
According to reference data, Algeria keeps about 40 SU-100s in reserve, the DPRK may have about a hundred self-propelled guns, Morocco has about two dozen SU-100s, but most likely they are no longer in operation. Until recently, Vietnam had about 80 vehicles, but it is not known whether they are currently in operation.
SU-100 on the street of Sana
As of 2014, there were three dozen SU-100s stored in Yemen. The self-propelled guns gradually deteriorated and stood in hangars, but they were remembered after the start of armed clashes between government forces and the Houthi group. Some of the self-propelled guns were revived and used by both the army and the Shiite rebels. The last time a Yemeni SU-100 was spotted on the move was in 2017.
To be continued ...
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