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The Samokhodnaya Ustanovka

By Sakhal

During the Russo-German conflict the Soviet engineers, with their magnific T-34, pointed the way to follow on tank design to their German counterparts. But it is not less true that they would have to learn from the Germans as well. Indeed, they were unpleasantly surprised by the excellent qualities shown by the Sturmgeschutz or German assault cannons. These vehicles mounted a cannon in a fixed casemate and resulted ideal as anti-tank weapon, specially when used from camouflaged or sheltered positions. Besides, the lack of a rotatory turret greatly simplified the production process thus reducing the costs. Naturally, the Russian would soon crystallize their idea of an assault cannon. The first tank of this type produced in the Soviet Union was a self-propelled 122-millimeter howitzer, installed upon the conveniently modified chassis of the medium tank T-34. This new tank was called SU-122; the two initials meant Samokhodnaya Ustanovka or "Self-propelled Cannon", denomination which would receive in the future all the Soviet tanks which lacked a turret.

The SU-122 was designed by engineer E. W. Silniszczkov with assistance from General F. F. Petrov, master per excellence of the Soviet tank designers, who had projected the 122-millimeter howitzer. This one, officially denominated M-30S, was an excellent weapon with a muzzle speed of 515 meters/second, a range of 11800 meters and a rate of fire of 5-6 rounds per minute. This machine had its operational debut during the Battle of Kursk in the summer of 1943, forming part of the units of the Soviet artillery. They are remarkable for taking part in the reconquest of Orel, north of Kursk, during the acts of persecution subsequent to the battle. But meanwhile, in an industrial complex nearby to the Ural Mountains, called Tankograd because there were produced massively the Soviet tanks, a team of engineers led by L. S. Troyanov and S. N. Machonin was designing a new self-propelled cannon.

SU-85 and SU-100

With the deployment in 1943 of the new German tanks Tiger and Panther the Soviets were in a hurry to achieve the means to counteract this new threat. The medium tank of that time was insufficiently armed with a rather short 76.2-millimeter cannon and the two normalized self-propelled cannons, the SU-76 and the SU-122, did not have enough firepower to pose a true challenge to the new enemy tanks. The Designs Bureau, directed by L. I. Gorlits and F. F. Petrov, was in charge of the design of the SU-85 according to a resolution from the State Defense Committee. The projectists were entrusted the task of producing, in the briefest time and with the lesser cost possible, new models of self-propelled cannons with the following characteristics: high mobility, excellent firepower, flexibility and rate of fire, to which was added a fast production and very low cost per unit. To develop the new self-propelled cannon, the projectists thought appropriate - from a logistic standpoint and to achieve a faster production - to reuse the chassis of the SU-122 designing a new superstructure to house the artillery piece and the whole crew. This would lower the profile of the vehicle and render it less vulnerable to enemy shots.

The adaptation work on the chassis was completed by the project teams of Uralmashzavod in Sverdlovsk and the Kirov Factory in Chelyabinsk, led by Troyanov. Gorlits became the chief projectist of the new vehicle. The development of the armament was carried out by the team led by General Petrov. To produce the 85-millimeter cannon the Soviet engineers used as base the anti-aircraft cannon Model 1939, designed by Petrov. The remodelation of this cannon was called D-5S-85A Model 1943. It is noteworthy the parallelism of this weapon with the famous 88-millimeter that equipped the Tiger tank and which had been adapted as well from an anti-aircraft weapon. The D-5S-85A had a length of 51.5 calibers and could fire a 9.02-kilogram piercing projectile with a muzzle speed of 792 meters/second, being capable of perforating 100 millimeters of vertical armor from a distance of 1000 meters. The rate of fire was from 8 to 10 rounds per minute. Once installed in the casemate, the cannon had a firing arc of 20 degrees in horizontal and from -5 to +25 degrees in vertical.

After three months of intensive work the prototypes of the SU-85 were completed and in August 1943 they were submitted for driving and firing tests. The vehicle had a good maneuverability and mobility, being able to reach a road speed of 50 kilometers/hour. On the other hand it had capacity for 45 projectiles. The 7th August the new self-propelled cannon was accepted and normalized in the Soviet Supreme Command, thus it started to be produced in the industrial complex Uralmashzavod. The Project Bureau led by L. Lulievim disposed a special group of engineers, in collaboration with the technicians of the factory, to prepare the production. Much attention was put for improving the project to reduce the cost per unit and simplify the production of the armament. The project team led by N. Turin produced a machine for producing cannon tubes by centrifugal casting. All the efforts made to accelerate the production were finished in a month. Consequently, at the end of August 150 vehicles had been produced and at the end of the year 750 units had been delivered to the Red Army. The individual series of SU-85 were different to each other in some details and equipments.

The Samokhodnaya Ustanovka

The crew comprised four members. The commander, placed at the right, had at his disposal a rather prominent cupola which in the last series of vehicles was replaced by one similar to that of the T-34/76, the M-43 fitted with improved sight blocks which nonetheless were always of mediocre quality. The gunner was placed to the left of the cannon and the loader behind the commander. Optical equipment included a panoramic periscope and the telescopic gunsight TSh-15. The driver was placed to the left as well and in the uncomfortable situation of being surrounded by projectiles. Since this one was isolated from the rest of the crew by an armored plate the SU-85 had an intercommunication system as standard equipment. On the other hand the vehicle lacked any form of secondary armament. The SU-85 had been created as well to follow the infantry so it was fitted with large handholds; following the Soviet use, the soldiers could travel perched on the vehicle, remaining in the center of the combat and attacking with effectiveness static and mobile targets.

The SU-85 arrived too late for the Battle of Kursk, entering action in December 1943. In the battles fought in Ukraine and the Dnieper, in 1944, it soon earned the sympathy of its crews and the respect of the enemy. In that same year, due to the introduction of the T-34/85, the SU-85 started to be outclassed so they received new cannons of the same caliber but of increased range and penetration. In this form they were delivered to satellite countries such as Poland and Czechoslovakia, where they replaced as anti-tank weapon the more primitive SU-76, which from that moment was relegated to serve as artillery support for the infantry units. The Soviet Army incorporated 21 vehicles in the battalions of self-propelled artillery. One of them was the chief of four batteries comprising five units each, of which one was the chief of battery. The tank armies incorporated 31 units in their self-propelled regiments so the commanders could use them as their will.

When in the late 1944 the production of the SU-85 was discontinued, in favor of the SU-100, 2050 units had been produced. A good proof of the quality of this project could be the exemplar captured in good conditions of operation by the soldiers of the Gross Deutschland Division in the mid 1944, and immediately put into service against its original owners. This German unit had full companies equipped with captured Soviet material. With the purpose of identifying the vehicle without mistake the crosses were painted considerable larger than usual, even if this greatly compromised the camouflage.

The Samokhodnaya Ustanovka

Specifications for SU-85

Crew: 4

Armament: One D-5S Model 1943 85-millimeter cannon

Ammunitions: 45 for 85-millimeter cannon

Armor: 20-45 millimeters

Lenght (total): 8.5 meters

Width: 3 meters

Height: 2.45 meters

Weight: 29.6 tonnes

Ground pressure: 0.7 kilograms/square centimeter

Ground clearance: 43 centimeters

Engine: V-2-34 Diesel of 12 cylinders, water-cooled, of 500 horsepower at 1800 revolutions per minute

Power/weight ratio: 16.8 horsepower/tonne

Maximum speed (in road): 50 kilometers/hour

Maximum speed (in countryside): 40 kilometers/hour

Maximum operational range (in road): 290 kilometers (400 kilometers with external fuel tanks)

Maximum operational range (in countryside): 201 kilometers

Maximum surmountable trench: 2.5 meters

Maximum surmountable step: 0.75 meters

Maximum surmountable slope: 35 degrees

Maximum fording: 1.3 meters

When the 85-millimeter cannon was adapted to the medium tank T-34 to form the T-34/85 it became mandatory to increase the firepower of the self-propelled cannon based in that same chassis. The SU- 85 could no longer be considered as a support vehicle for the medium tank, so in the late 1944 it started to be replaced by the SU-100. This one was very similar to its predecessor but carried a 100-millimeter cannon, the D-10S Model 1944, projected as well by the team led by General F. F. Petrov, but this time based on a naval cannon developed in the prewar years. This one was a double- purpose weapon of 56 calibers in length and high muzzle velocity. The SU-100 started to be produced in Uralmashzavod in September 1944 and at the end of the year around 500 exemplars had been delivered to the Red Army; at the end of the war about 1800 units had been produced. The SU-100 constituted the normalized support cannon for the armored and mechanized divisions until being replaced in 1957 by the ISU-122, based on the chassis of the heavy tank IS-2.

The SU-100 proved to be a very effective means of destroying the German heavy tanks (Panther and Tiger) and tank destroyers (Ferdinand, Jagdpanther and Jagdtiger) and in this regard it played a very relevant role during the last months of the war. The 100-millimeter cannon had very increased prestations over those of the 85-millimeter counterpart. It could fire 16-kilogram high-explosive grenades or 19.5-kilogram shrapnel grenades to distances of up to 19200 meters, apart from piercing projectiles. The number of projectiles carried was reduced to 34. Apart from its cannon, the SU- 100 could be differentiated from its predecessor by the new shape of the mantlet and the cylindrical cupola protruding on the upper right side of the superstructure. After the war a number of SU-85 and SU-100 had their cannons removed for being used as armored command and rescue vehicles. The holes left by the removed weapons were adequately covered with armored plates.

Three decades after being put into service in the Soviet Army the SU-100 still enjoyed wide utilization in the countries of the Eastern Bloc and also in the Middle East, despite being obsolete. In the Yom Kippur War of 1973 Egypt and Syria deployed battalions of SU-100 along with each armored, mechanized and infantry division. The Israeli said to have captured many SU-100. Circa 1980 the SU-100 continued in service in Albania, Algeria, Bulgaria, China, Cuba, Czechoslovakia, East Germany, Egypt, Irak, Mongolia, Morocco, North Korea, North Yemen, Romania, Soviet Union, Syria and Yugoslavia. Already in the 1990s, the SU-100 took part in the Yugoslavian War where it was considered of satisfactory performance, but quickly retired due to lack of spare parts. As 2016 goes by the SU-100 probably remains in service with the Vietnam People's Army and the Korean People's Army, and some unit has been seen in the Yemeni Civil War.

The Samokhodnaya Ustanovka

Specifications for SU-100

Crew: 4

Armament: One D-10S Model 1944 100-millimeter cannon

Ammunitions: 34 for 100-millimeter cannon

Armor: 20-75 millimeters

Lenght (total): 9.45 meters

Width: 3 meters

Height: 2.25 meters

Weight: 31.6 tonnes

Ground pressure: 0.82 kilograms/square centimeter

Engine: V-2-34 Diesel of 12 cylinders, water-cooled, of 500 horsepower at 1800 revolutions per minute

Power/weight ratio: 16 horsepower/tonne

Maximum speed (in road): 48 kilometers/hour

Maximum operational range (in road): 320 kilometers

Maximum surmountable trench: 3 meters

Maximum surmountable step: 0.64 meters

Maximum surmountable slope: 30 degrees


Until the introduction of the ASU-85 in 1961 the only self-propelled anti-tank weapon available for the airborne units in the Soviet Union was the ASU-57. This one had two serious inconveniences: the inadequate caliber of the cannon against modern tanks and the poor armor with null protection in the upper part. Each airborne regiment had a battery of nine ASU-57 whereas each airborne division had a battalion of eighteen ASU-85. ASU stands for Aviadezantnaya Samokhodnaya Ustanovka or "Airborne Self-propelled Cannon". The ASU-85 was generally transported by an aircraft Antonov An-12 "Cub" and could be dropped by parachute. For this operation the vehicle was placed in a platform to which a good number of parachutes were attached. Almost immediately before reaching the ground, some retrorockets would be activated to diminish the impact and prevent damages to the cargo.

The Samokhodnaya Ustanovka

The hull is made of welded steel and has a thickness which varies from 10 millimeters in the roof to 40 millimeters in the front and mantlet. The combat compartment is in fore position and the engine and transmission are in the rear part. Many of the components of the ASU-85, particularly the chassis, were taken from the light amphibious tank PT-76. However the ASU-85 lacks amphibious capabilities, but it is able to ford up to 1.1 meters without any preparation. The crew comprises the commander, gunner, loader and driver, this one placed in the front to the right. The suspension is based on torsion bars, with six single road wheels, a fore drive sprocket and a rear idler on each side, and without return rollers. As in other Soviet tanks, the ASU-85 can increase its operational range with two external fuel tanks. There is also NBC protection and an infrared device for driving, as well as two infrared projectors, a fixed one installed upon the main armament and another one installed before the commander's cupola, orientable from inside the vehicle.

The 85-millimeter cannon is fitted with a double-fin muzzle brake and a bore evacuator, and it is installed slightly to the left side of the vehicle. The firing arc covers only 12 degrees in horizontal and from -4 to +15 degrees in vertical. Coaxially to the main armament there is a 7.62-millimeter machine gun. The vehicle transports a total of 40 projectiles of three different types: fragmentation, high-explosive piercing and subcalibrated piercing. The first one weighs 9.5 kilograms and has a muzzle velocity of 792 meters/second; the second one weighs 9.3 kilograms and has the same muzzle velocity, being able to perforate 102 millimeters of armor from a distance of 1000 meters; and the third one weighs only five kilograms but has a muzzle velocity of 1030 meters/second, being able to perforate 130 millimeters of armor from the same distance.

The Samokhodnaya Ustanovka

Specifications for ASU-85

Crew: 4

Armament: One D-70 Model 1956 85-millimeter cannon; one 7.62-millimeter coaxial machine gun; one 7.62 or 12.7-millimeter anti-aircraft machine gun (optional)

Ammunitions: 40 for 85-millimeter cannon; 2000 for 7.62-millimeter coaxial machine gun

Armor: 10-40 millimeters

Lenght (total): 8.49 meters

Lenght (hull): 6 meters

Width: 2.8 meters

Height: 2.1 meters

Weight: 14 tonnes

Ground pressure: 0.44 kilograms/square centimeter

Ground clearance: 37 centimeters

Engine: YaMZ-206V Diesel of 6 cylinders, water-cooled, of 240 horsepower at 1800 revolutions per minute

Power/weight ratio: 17.1 horsepower/tonne

Maximum speed (in road): 44 kilometers/hour

Maximum operational range (in road): 260 kilometers

Maximum surmountable trench: 2.8 meters

Maximum surmountable step: 1.1 meters

Maximum surmountable slope: 70 percent

Maximum fording: 1.1 meters

Categories: Tanks - World War Two - Cold War - 20th Century - [General]


Website: Military History

Article submitted: 2016-09-22

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