The Red Army entered the Second World War without having a single serial version of the self-propelled guns in the army, which could be used both to support the infantry in the offensive and to fight enemy tanks. The SU-5 self-propelled guns that entered service at the end of the 1930s, created on the basis of the T-26 light tank, were produced in a very small series and were used only sporadically during a campaign in Poland. In the summer of 1941, the question of the need for self-propelled guns became so acute that by the end of the year a surrogate self-propelled gun ZIS-30, created on the basis of the Komsomolets artillery tractor, was born. This vehicle had a small power reserve, was unstable and overweight, although it could quite successfully hit almost all the armored vehicles of the Wehrmacht.
An attempt to develop a fully armored self-propelled gun armed with a 76-mm cannon was undertaken by the Gorky Automobile Plant on its own initiative in the fall of 1941. At the same time, the enterprise mastered the production of a light tank T-60 and was engaged in the design of a more advanced vehicle - the T-70. Using elements of the transmission and chassis of these tanks, the designers created the SU-71 self-propelled artillery unit with two parallel 6-cylinder GAZ-202 automobile engines located in parallel. Along with it, work was underway on a unified anti-aircraft gun SU-72 with a 37-mm automatic cannon in a rotating turret. However, in the end, none of the cars went into production.
The situation changed only by the spring of 1942, when the USSR saw a turning point in the increase in the production of armored vehicles and the task of creating an ACS arose with renewed vigor. It was quite obvious that in modern war conditions, self-propelled artillery should have supported the infantry, cavalry and tanks in the offensive, which could easily maneuver on the ground, approach the enemy and be protected from his machine-gun fire. The self-propelled guns could quite effectively and without long preparation destroy enemy tanks and their firing points with direct fire, as well as from closed positions.
By July 1942, the first sample of the OSU-76 self-propelled gun was built, created on the basis of the T-60 tank, but equipped with a cheaper M-1 automobile engine in production. This vehicle turned out to be unstable when firing due to its rather short base, and its armor protection was too weak. In fact, creating a full-fledged, mobile, sufficiently protected self-propelled divisional cannon of limited mass (up to 10 tons), which the chassis of a light tank could withstand, was a non-trivial task.
Aware of the need for self-propelled guns for the front, the State Defense Committee (GKO) by December 1, 1942 orders to create a new self-propelled installation. This time, the chassis of the T-70 tank was taken as a basis, which was well mastered by the industry. The combat compartment of the ACS was located at the rear in such a way that the barrel of the ZIS-3 gun did not go beyond the dimensions of the vehicle. The power plant included 2 parallel operating GAZ-202 engines with a total power of 140 hp. Exactly the same engine (in one copy) was used on the T-60 tank.
First of all, the designers were attracted by the possibility of the ACS moving on one engine when another engine fails, as well as the unification of the machine with the mastered units and the ease of replacement. For some reason, the design did not take into account the experience of unsuccessful use of blocks of two parallel motors that would work on 1 output shaft. The creators ignored the serial connection of engines in line, which was already used on the T-70 tank. Be that as it may, the created self-propelled gun was tested and was put into service under the designation SU-76. Its serial production began in January 1943, and at the end of the month the first 2 regiments armed with self-propelled guns departed for the Volkhov front. It was here that the cars and "rained down". The congenital defect of such a connection of the engines made itself felt - during operation, resonant torsional vibrations occurred, which very soon led to the failure of the transmission.
In March 1943, the production of self-propelled guns was stopped (about 170 vehicles were produced). The car had to get rid of all the shortcomings as soon as possible. As a result, by May 1943, a new version, called the SU-76M, was put on the assembly line. The vehicle was promptly redesigned for the installation of the engine from the T-70 tank, the roof was removed from the fighting compartment, which interfered with the aiming of the gun and the work of the crew, the transmission and control were simplified, the weight of the vehicle decreased from 11, 2 to 10, 5 tons. Already in July 1943, the new self-propelled gun received the baptism of fire during the battle on the Kursk Bulge.
Description of construction
The SU-76 is a semi-open self-propelled gun with a rear-mounted fighting compartment. In front of the armored hull there was a driver's seat, propulsion system and transmission, gas tanks. The engine was located to the right of the center line of the self-propelled gun. The gun, ammunition and the seats of the rest of the crew were in the aft part in the open top and rear conning tower.
The fighting compartment was a wheelhouse, which was protected by two side and front armor plates. The booking was differentiated bulletproof. The frontal sheet of the cabin hull is 35 mm thick. was located at an angle of 60 degrees to the normal, the side walls of the cabin were 10 mm thick. and were located at an angle of 25 degrees. Self-propelled gun armor protected the crew of 4 from small arms fire and large shrapnel. The rear wall of the wheelhouse was below the sides and had a special door. To protect against bad weather, the self-propelled gun used a tarpaulin awning, which served as a roof. The commander of the self-propelled guns was located to the right of the gun, the gunner to the left, and the loader from behind. All SU-76 vehicles were equipped with transmitting and receiving radio stations and a tank intercom.
ACS SU-76 was equipped with a power plant, which consisted of two 4-stroke inline six-cylinder GAZ-202 carburetor engines with a total capacity of 140 hp. ACS of later production series were equipped with up to 85 hp. engines. The self-propelled suspension was torsion bar, individual for each of the 6 small-diameter road wheels (on each side). The drive wheels were at the front, while the sloths were identical to the road wheels.
On the highway, the self-propelled gun could accelerate to 41-45 km / h, the speed on the ground was lower and amounted to 25 km / h. The cruising range on the highway was 250 km., On rough terrain - 190 km. SU-76 could overcome a trench up to 2 meters wide, climb a mountain with a slope of 30 degrees and overcome a ford up to 0.9 meters deep. Due to the low ground pressure (only 0.545 kgf / cm2), the SU-76 could move quite easily in wooded and swampy terrain, supporting the infantry where medium tanks and other self-propelled guns could not come to their aid. The developed cooling system and the presence of a trouble-free engine preheater made it possible to operate the car at any time of the year along the entire length of the Soviet-German front from the northern regions of Karelia to the Crimea. Automotive 6-cylinder engines, which were mastered in production shortly before the start of the war, successfully worked in a tense tank mode. The unusual installation of engines in the "back of the head" of each other was not used anywhere else in the world.
The main armament of the self-propelled gun was the ZIS-3 universal divisional gun. The sub-caliber projectile of this gun at a distance of half a kilometer was able to penetrate armor up to 91 mm thick. That is, the gun could hit any place in the hull of German medium tanks, as well as the sides of the Tigers and Panthers. In addition, the self-propelled guns had a portable DT machine gun for self-defense, for the same purposes the crew could use PPS and PPSh submachine guns, as well as several F-1 hand grenades.
The ZIS-3 gun had a barrel length of 40 calibers, a wedge vertical bolt and a semi-automatic mechanism. The armor-piercing projectile of this gun weighed 6, 3 kg, high-explosive fragmentation - 6, 2 kg. The muzzle velocity of the armor-piercing projectile was 662 m / s. The gun was mounted on a machine tool behind an armored wheelhouse shield. The recoil mechanisms were enclosed in an armored casing. The sighting equipment consisted of a standard panoramic sight. The vertical guidance angles were from -5 to +15 degrees, the horizontal guidance angles were 15 degrees (in each direction). Self-propelled ammunition included 60 unitary rounds, among which could be armor-piercing, high-explosive fragmentation and cumulative. A sufficiently trained crew could achieve a rate of fire of 8-10 rounds per minute.
The low metal consumption of the SU-76 ACS, as well as the use of automotive components and assemblies well-developed by the Soviet industry in its design, determined its mass production. This, in turn, made it possible in the shortest possible time to strengthen and compact the artillery formations of the infantry, which quickly fell in love and appreciated these machines at their true worth. A total of 14,292 such SPGs were produced from 1943 to 1945. It was the SU-76 that became the second largest armored vehicle of the Red Army after the T-34 tank.
Combat use
The SU-76 was designed to provide fire support for infantry on the battlefield and was used as a light assault gun or tank destroyer. It completely replaced the light tanks of close support of the infantry, which were common in the Red Army. At the same time, the assessment of the car was quite controversial. The infantrymen liked the SU-76 self-propelled guns, since its firepower was superior to the T-70 tank, and the open wheelhouse made it possible to closely interact with the crew, especially in urban battles. At the same time, the self-propelled guns themselves often noted the weak points of the machine, which included, in particular, weak bulletproof booking, an increased fire hazard of a gasoline engine and an open conning tower that did not protect against fire from above. At the same time, the open wheelhouse was convenient for the crew, and also removed the problem of gas pollution in the fighting compartment during firing, and also made it possible, if necessary, to quickly leave the ACS. Also, the positive aspects of the car were reliability, ease of maintenance, low noise, high cross-country ability.
As a tank destroyer, the SU-76 could quite successfully fight against all types of light and medium tanks of the Wehrmacht, as well as with its equivalent self-propelled guns of the Germans. The self-propelled gun had a chance of winning even against the Panther, piercing its thin side armor. At the same time, it was ineffective against the "Tiger" and heavier vehicles. When meeting with heavy tanks, the crew could fire on the chassis or try to damage the barrel, as well as hit the side from close distances. The introduction of sub-caliber and cumulative shells into the ammunition load somewhat simplified the fight against well-armored targets, but did not completely solve the problem.
Competent use of the terrain and camouflage when maneuvering from one shelter dug in the ground to another allowed experienced self-propelled gun crews to successfully repel German tank attacks. Sometimes the SU-76 was used to fire from closed positions. The elevation angle of her guns was the highest among all Soviet self-propelled guns, and the maximum firing range was 17 km. At the final stage of the war, self-propelled guns were often used in the role of ersatz-armored personnel carriers, vehicles for evacuating the wounded, and also as a vehicle for forward artillery observers.
Performance characteristics: SU-76
Weight: 10, 5 tons.
Dimensions:
Length 5 m, width 2, 74 m, height 2, 2 m.
Crew: 4 people.
Reservation: from 7 to 35 mm.
Armament: 76, 2-mm cannon ZIS-3
Ammunition: 60 rounds
Engine: two 6-cylinder gasoline engines GAZ 202, 70 hp each. each.
Maximum speed: on the highway - 44 km / h, on rough terrain - 25 km / h
Progress in store: on the highway - 250 km, on rough terrain - 190 km.
