During the war years, the tasks of providing fire support to the infantry units of the Red Army were mainly assigned to 76, 2-mm regimental and divisional guns. After the stabilization of the front line and the start of offensive operations, it turned out that, due to the lack of tractors, the artillery towed by horse teams often did not have time to change the firing position in time, and it was very difficult to roll the guns by the crew following the advancing infantry over rough terrain. In addition, the crews of guns firing direct fire at enemy firing points suffered heavy losses from bullets and shrapnel. It became obvious that the Soviet troops needed self-propelled artillery installations capable of taking over part of the functions of divisional artillery. From the very beginning, it was envisaged that such self-propelled guns should not directly participate in the attack. Moving at a distance of 500-600 meters from the advancing troops, they could suppress firing points, destroy fortifications and destroy enemy infantry with the fire of their guns. That is, a typical "artillery attack" was required, to use the terminology of the enemy. This set different requirements for ACS compared to tanks. The protection of self-propelled guns could be less, but it was preferable to increase the caliber of the guns and, as a result, the power of the action of the shells.
Although the self-propelled gun, armed with a 76, 2-mm divisional gun, could have been created much earlier, work on the design of such an SPG at plant number 38 in the city of Kirov began only a year after the start of the war, and the assembly of the first vehicles was completed in the late autumn of 1942.
The SU-76 self-propelled artillery mount was created on the basis of the T-70 light tank using a number of automotive units and is armed with the 76-mm ZIS-ZSh (Sh - assault) gun, a variant of the divisional gun specially developed for the ACS. The vertical guidance angles ranged from -3 to + 25 °, in the horizontal plane - 15 °. The vertical aiming angle made it possible to reach the firing range of the ZIS-3 divisional gun, that is, 13 km, and when conducting hostilities in the city, shelling the upper floors of buildings. When firing direct fire, the standard sight of the ZIS-Z gun was used, when firing from closed firing positions, a panoramic sight. The combat rate of fire did not exceed 12 rds / min. Ammunition - 60 shells.
Self-propelled artillery mount SU-76
Due to the need to place a rather large gun in a combat vehicle, the body of the T-70 tank had to be lengthened, and after it the chassis was lengthened. The SU-76 had an individual torsion bar suspension for each of the 6 small-diameter road wheels on each side. The drive wheels were located at the front, and the sloths were identical to the road wheels. The propulsion system, transmission and fuel tank were located in front of the vehicle's armored hull. The SU-76 was driven by a power plant of two 4-stroke inline 6-cylinder GAZ-202 carburetor engines with a total capacity of 140 hp. with. The capacity of the fuel tanks was 320 liters, the vehicle's cruising range on the highway reached 250 km. The maximum speed on the highway was 41 km / h. On the field - up to 25 km / h. Weight in firing position - 11, 2 tons.
Frontal armor 26-35 mm thick, side and stern armor 10-15 mm thick provided protection for the crew (4 people) from small arms fire and shrapnel. The first serial modification also had an armored 6-mm roof. Initially, the self-propelled gun was supposed to have an open-top wheelhouse, but Stalin personally ordered to provide the SPG with a roof.
The first serial SU-76s in the amount of 25 units were sent to a self-propelled artillery training regiment at the beginning of 1943. In February, the first two self-propelled artillery regiments (SAP), equipped with the SU-76, went to the Volkhov front and took part in breaking the blockade of Leningrad. Initially, the SU-76s were sent to the SAP, which also had the SU-122, but later, to facilitate logistics and repairs, each regiment was equipped with one type of ACS.
During the fighting, self-propelled guns demonstrated good mobility and maneuverability. The firepower of the guns made it possible to effectively destroy light field fortifications, destroy accumulations of manpower and fight against enemy armored vehicles.
Having a high cross-country ability and a relatively low weight, the SU-76 was capable of operating where heavier vehicles could not be used at all or were used ineffectively: in mountainous-wooded or swampy areas. Due to the gun elevation angle, significant for the ACS, the installation could fire from closed positions.
But, unfortunately, with all its merits and relevance, the first serial SU-76s demonstrated unsatisfactory technical reliability in difficult front-line conditions. In combat units, there was a massive failure of transmission elements and engines. This happened due to erroneous technical solutions incorporated during the design and due to the unsatisfactory quality of the manufacture of engines and transmissions. To eliminate the main problems that led to massive breakdowns, serial production was stopped, and qualified factory brigades were sent to the front-line workshops involved in the restoration of the SU-76.
Before serial production was stopped, 608 SU-76s were built. A number of repaired self-propelled guns survived until the summer of 1943. So, on the Kursk Bulge, 11 SU-76s fought as part of the 45th and 193rd tank regiments. Another 5 self-propelled guns of this type were in the 1440th SAP. In the summer heat, the temperature in the fighting compartment inside the closed wheelhouse often exceeded 40 ° C. Due to poor ventilation during firing, high gas pollution arose and the working conditions of the crew were very difficult. In this regard, the SU-76 received the nickname "gas chamber".
Self-propelled artillery mount SU-76M
After the adoption of rather tough disciplinary measures, the SU-76 was modernized. In addition to improving the quality of production vehicles, changes were made to the design of the engine-transmission and chassis to improve reliability and increase the service life. The self-propelled unit with an engine-transmission group borrowed from the T-70B light tank was designated SU-76M. Subsequently, the power of the twin propulsion system was increased to 170 hp. Two elastic couplings were installed between the engines and gearboxes, and a friction slipping clutch was installed between the two main gears on a common shaft. Thanks to this, it was possible to increase the reliability of the engine-transmission part to an acceptable level.
The thickness of the frontal armor, sides and stern remained the same as that of the SU-76, but the armored roof of the fighting compartment was abandoned. This made it possible to reduce the weight from 11.2 to 10.5 tons, which reduced the load on the engine and chassis. The transition to an open-top fighting compartment solved the problem of poor ventilation and improved visibility of the battlefield.
The installation could overcome a trench up to 2 m wide and rise up to 30 °. Also SU-76M was able to force a ford to a depth of 0.9 m. The undoubted advantages of the installation could be attributed to its small size, low specific pressure on the ground, which was 0.545 kgf / cm². The self-propelled gun could move through wooded and swampy terrain. It was possible to accompany the infantry in those places where medium tanks could not move. The range of the self-propelled gun on the highway was 320 km, on a dirt road - 200 km.
In the stowed position, to protect against road dust and precipitation, the fighting compartment was covered with a tarpaulin. For self-defense against enemy infantry, the DT-29 machine gun appeared in the armament.
ACS SU-76 and SU-76M during the war years were equipped with several dozen self-propelled artillery regiments. At the beginning of 1944, the formation of self-propelled artillery divisions began (each had 12, and later 16 SU-76Ms). They replaced individual anti-tank divisions in several dozen rifle divisions. At the same time, they began to form light self-propelled artillery brigades of the RVGK. These formations each had 60 SU-76M installations, five T-70 tanks and three American M3A1 Scout Car armored vehicles. In total, four such brigades were formed in the Red Army. Until the end of World War II, more than 11,000 SU-76Ms were received by the troops.
Initially, many commanders of tank and combined-arms formations, having no idea about the tactics of self-propelled artillery, often sent lightly armored self-propelled guns in frontal suicidal attacks along with medium and heavy tanks.
Incorrect use, as well as the fact that at first the crews of self-propelled guns were manned by former tankers, led to a high level of losses. The most at risk of the crew members was the driver, whose workplace was located next to the gas tank, and in the event of a shell hit, he could be burned alive. As a result, at the first stage of combat use, the light self-propelled gun was not popular among the personnel and earned many unflattering nicknames. But with proper use, the SU-76M fully justified itself and was a very good alternative to the ZIS-3 towed divisional gun. With the accumulation of experience, the effectiveness of the actions of self-propelled guns, armed with a 76, 2-mm cannon, has significantly increased.
At the time of its appearance, the SU-76 could quite successfully fight against German tanks. However, by mid-1943, after a sharp increase in the protection and firepower of the German 76 tanks, the 2 mm gun became less effective. For example, the most massive modification of the German "Quartet" (more than 3800 vehicles were built), the medium tank Pz. KpfW. IV Ausf. H, which began production in April 1943, had frontal hull armor 80 mm thick and was armed with a very effective 75-mm gun KwK.40 L / 48 with a barrel length of 48 calibers.
The firepower and protection of the heavy German tanks PzKpfw V Panther and Pz. Kpfw Tiger was even higher, which made the fight against them a very difficult task. According to the reference data, the 53-BR-350A blunt-headed armor-piercing projectile, which was included in the ammunition load of the ZIS-3 gun, could penetrate 73 mm armor at a distance of 300 m along the normal; at an angle of meeting with 60 ° armor at the same distance, armor penetration was 60 mm. Thus, the 76, 2-mm gun mounted on the SU-76M could confidently penetrate only the side armor of the "fours" and "Panthers". At the same time, firing cumulative shells used in regimental guns was strictly prohibited due to the unreliable operation of the fuses and the risk of bursting in the barrel when firing from 76, 2-mm divisional and tank guns. The information that cumulative shells appeared in the ZIS-3 ammunition at the end of 1944 does not correspond to reality.
In the second half of 1943, production of 76, 2-mm 53-BR-354P subcaliber shells began. This projectile weighing 3.02 kg had an initial speed of 950 m / s and at a distance of 300 m, along the normal, it was able to overcome 102-mm armor. At a distance of 500 m, armor penetration was 87 mm. Thus, operating from an ambush with a minimum firing range in the presence of sub-caliber shells in the ammunition load, the SU-76M crew had a good chance of hitting a German heavy tank. Another question is that sub-caliber shells were primarily sent to anti-tank battalions. If they were in the SU-76M ammunition, then in a very limited number, and were on special account.
However, in the fight against enemy armored vehicles, much depended on the technical condition of the vehicle, the level of training of the crew and the tactical literacy of the commander. The use of such strong qualities of the SU-76M as good mobility and high cross-country ability on soft soils, camouflage taking into account the terrain, as well as maneuvering from one shelter dug in the ground to another often made it possible to achieve victory even over heavy enemy tanks. From the second half of 1944, the importance of the SU-76M as an anti-tank weapon decreased. By that time, our troops were already sufficiently saturated with specialized anti-tank guns and tank destroyers, and enemy tanks became a rarity. During this period, the SU-76Ms were used exclusively for their intended purpose, as well as for transporting infantry, evacuating the wounded, and as vehicles for forward artillery observers.
Self-propelled artillery mount SU-76I
Talking about Soviet self-propelled artillery mounts armed with a 76, 2-mm gun, one cannot fail to mention the self-propelled guns built on the basis of captured German tanks Pz. Kpfw III and ACS StuG III. Although not many of these machines were produced, at a certain stage they played a noticeable role in the course of hostilities. By mid-1942, Soviet troops captured more than 300 serviceable or recoverable Pz. Kpfw III and ACS StuG III. Since the standard armament of these vehicles for a number of reasons did not satisfy the Soviet command, it was decided to use the captured chassis to create a 76, 2-mm self-propelled gun.
During the design process, the ACS received the designation SU-76 (T-III), then SU-76 (S-1) and finally SU-76I. The installation was officially put into service on March 20, 1943, and in May the first SU-76Is entered the Moscow Self-Propelled Artillery Training Center. When forming units equipped with new self-propelled guns, the same regular order was used as for the SU-76, but instead of the commander's T-34s, at first they used captured Pz. Kpfw III, which were then replaced by the SU-76I in the command version. The release of self-propelled guns on a trophy chassis continued until November 1943 inclusive. In total, they managed to assemble 201 SU-76Is, of which more than 20 were in the command version.
The vehicle based on the Pz. Kpfw III, according to a number of parameters, looked more preferable than SU-76 and SU-76M. First of all, the SU-76I won in terms of the safety and reliability of the engine-transmission group.
The self-propelled unit had a booking of the frontal part of the hull with a thickness of 30-50 mm, the side of the hull - 30 mm, the forehead of the cabin - 35 mm, the side of the cabin - 25 mm, the feed - 25 mm, the roof - 16 mm. The wheelhouse had the shape of a truncated pyramid with rational angles of inclination of armor plates, which increased armor resistance. Such armor protection, which ensured invulnerability from 20-mm and partly from 37-mm shells, would have looked good in June 1941, but in mid-1943 it could no longer protect against 50- and 75-mm German guns.
Some of the vehicles intended for use as commanders were equipped with a powerful radio station and a commander's cupola with a Pz. Kpfw III. When creating the SU-76I, the designers paid special attention to the review from the combat vehicle. In this regard, this self-propelled gun outperformed most Soviet tanks and self-propelled guns produced in the same time period.
Initially, the plan was to arm the SU-76I with the 76.2 mm ZIS-3Sh cannon. But in this case, reliable protection of the embrasure of the gun from bullets and shrapnel was not provided, since cracks formed in the shield when lifting and turning the gun. As a result, the designers opted for the 76.2 mm S-1 gun. It was created on the basis of the tank F-34, especially for the light experimental self-propelled guns of the Gorky Automobile Plant. Vertical guidance angles: from -5 to 15 °, horizontally - in the sector ± 10 °. The practical rate of fire of the gun was up to 6 rds / min. In terms of armor penetration characteristics, the S-1 gun was completely identical to the tank F-34. The ammunition load was 98 shells. For firing, the entire range of artillery rounds from 76, 2-mm tank and divisional guns could be used. On command vehicles, due to the use of a more powerful and cumbersome radio station, the ammunition load was reduced.
Cases of successful use of SU-76I against German tanks Pz. Kpfw III and Pz. KpfW. IV. But in the summer of 1943, when the self-propelled guns first went into battle, their firepower was no longer enough for a confident fight with all the armored vehicles available to the Germans. Nevertheless, the SU-76I enjoyed popularity among the crews, who noted higher reliability, ease of control and an abundance of observation devices compared to the SU-76. In addition, in terms of mobility on rough terrain, the self-propelled gun was practically not inferior to the T-34 tanks, surpassing them in speed on good roads. Despite the presence of an armored roof, self-propelled guns liked the relative space inside the fighting compartment. Compared to other domestic self-propelled guns, the commander, gunner and loader in the conning tower were not too constrained. The difficulty of starting the engine at negative temperatures was noted as a significant drawback.
Self-propelled guns SU-76I fought until the summer of 1944. After that, the few surviving cars were written off due to the exhaustion of the resource of the chassis, engine and transmission. In training units, individual self-propelled guns served until the end of the war. Currently, the only surviving original SU-76I is installed in the city of Sarny, Rivne region (Ukraine).
During the war, this car fell from a bridge into the Sluch River and lay at the bottom for almost 30 years. Subsequently, the car was raised, restored and became a monument. The SU-76I self-propelled guns installed in Moscow on Poklonnaya Gora and in the UMMC Museum in the city of Verkhnyaya Pyshma, Sverdlovsk Region, are remakes created using the Pz. Kpfw III.
