SU-122 is a medium-weight Soviet self-propelled gun of the assault gun class (with minor restrictions it could serve as a self-propelled howitzer). This machine became one of the first self-propelled guns, which were adopted in large-scale production in the USSR. The impetus for the creation of the ACS was the need to simplify the design of the T-34 tank as much as possible in the difficult conditions for the country in the middle of 1942 and the need to give the tank and mechanized units a highly mobile and powerful means of fire support.
The plenum of the GAU Artillery Committee, which was held on April 15, 1942, in which representatives from the troops, industry, and the People's Commissariat of Armaments took part, determined the directions for the development of Soviet self-propelled artillery. The Red Army was supposed to receive an infantry support self-propelled gun armed with a 76-mm ZIS-3 divisional cannon, an M-30 122-mm howitzer and a self-propelled bunker fighter armed with an ML-20 152-mm howitzer cannon. In general, the decisions of the plenum boiled down to the creation of such a self-propelled artillery system, which could provide support and accompaniment of the advancing infantry and tanks with its own fire, was able to follow in the advancing order of troops and at any moment open fire to kill. The decisions taken at the plenum were approved by the State Defense Committee.
In the shortest possible time, by November 30, 1942, at the Ural Heavy Engineering Plant (UZTM, Uralmash), design work was completed and the first prototype of the SU-122 was manufactured. Due to the shortage of self-propelled artillery in the troops, the SU-122 self-propelled gun was put into mass production in December, during which the machine was constantly subjected to numerous modifications, which were associated with a hasty launch into a series and a short testing period. The self-propelled guns were produced from December 1942 to August 1943; a total of 638 self-propelled guns of this series were produced. The production of the SU-122 was discontinued due to the transition to the production of the SU-85 tank destroyer, which was created on its basis.
Design features
ACS SU-122 had the same layout as all other serial Soviet self-propelled guns, with the exception of only the SU-76. The fully armored hull was split into 2 parts. In the front there was an armored wheelhouse, which housed the crew, gun and ammunition - it combined the control compartment and the fighting compartment. The engine and transmission were located in the rear of the vehicle. The ACS crew consisted of 5 people. Three crew members were located to the left of the gun: the first was the driver, followed by the gunner, followed by the loader. Another 2 people were on the right of the gun - the commander of the self-propelled gun and the castle. The fuel tanks were located along the sides between the shafts of the individual spring suspension units, including in the vehicle's habitable compartment. This arrangement adversely affected the survival of the crew and explosion safety in the event of a self-propelled gun hit by an enemy projectile.
A relatively large self-propelled gun crew (5 people) was needed, since the 122-mm gun had separate loading, a piston bolt and a targeting mechanism spaced on both sides of the gun. The flywheel of the sector lifting mechanism was on the right, and the flywheel of the helical swing mechanism was located on the left.
The armored hull and cabin of the self-propelled guns were made of rolled armor plates with a thickness of 45, 40, 20 and 15 mm.by welding, self-propelled gun armor was projectile. The armored plates of the front of the cabin and the body of the self-propelled guns had rational angles of inclination. On the prototype and the first versions of the ACS, the frontal part of the wheelhouse was assembled from 2 armor plates installed at different angles of inclination, but later it was replaced with a single piece, which was installed at an angle of 50 degrees to the normal.
For the convenience of maintenance and repair, the over-engine armor plates were made removable, and the upper aft part was hinged. There were 2 large holes in the roof of the armored room - for installing a viewing turret of a panoramic sight and a hatch for embarking / disembarking the crew. This hatch (with the exception of the emergency in the bottom of the hull) was the only means of the crew to leave the ACS. The driver's hatch in the frontal armor plate of the wheelhouse was used only to monitor the road. Due to the howitzer's armored recoil devices, it could not be fully opened. All this taken together significantly complicated the evacuation of the crew from the wrecked vehicle.
The main armament of the self-propelled guns was a slightly modified M-30S howitzer, created on the basis of the M-30 rifled 122 mm howitzer of the 1938 model. The differences between the swinging parts of the towed and self-propelled versions were insignificant and were mainly associated with the need to mount the gun in the cramped space of the armored cabin. From the M-30 howitzer, the gun retained the controls for the aiming mechanisms spaced out on both sides of the barrel, which required the presence of two gunners in the ACS crew. The M-30S howitzer had a barrel length of 22.7 caliber, the range of direct fire was 3.6 km, the maximum firing range was 8 km. The range of elevation angles was from -3 to +20 degrees. The horizontal guidance sector was limited to 20 degrees. The swivel mechanism of the gun was of a screw type and was located to the left of the barrel, it was serviced by the gunner. The lifting mechanism of the gun was on the right, it had to be serviced by the commander of the ACS. The howitzer had a mechanical manual trigger.
Howitzer ammunition consisted of 40 rounds of separate-case loading. Most of the ammunition was high-explosive fragmentation shots. In some cases, to combat enemy tanks, at a distance of up to 1000 meters, cumulative shells were used, which, with a weight of 13, 4 kg., Were capable of penetrating 100 mm of armor. The mass of the high-explosive fragmentation projectiles was 21.7 kg. For self-defense, the SA-122 crew used 2 PPSh submachine guns (20 disks for 1420 rounds), as well as 20 F-1 hand grenades.
The SU-122 ACS was driven by a four-stroke V-shaped twelve-cylinder V-2-34 diesel engine, which was liquid-cooled. The maximum power is 500 hp. the diesel engine developed at 1800 rpm. The operating power was 400 hp, which was reached at 1700 rpm. The engine was started either with a 15 hp ST-700 starter, or with compressed air from 2 cylinders. The total capacity of the fuel tanks was 500 liters. This fuel supply was enough for 400 km. march on the highway.
The chassis of the self-propelled guns almost completely repeated the T-34 base tank. On each side, there were 5 gable road wheels of large diameter, with a rubber band, a sloth and a drive wheel. There were no support rollers in the undercarriage, the upper part of the track rested on the self-propelled road wheels. Sloths with a caterpillar tensioning mechanism were located in the front, and the driving wheels of the ridge engagement were in the back. To improve cross-country ability, the tracks could be equipped with special lugs of various designs, which were bolted to every fourth or sixth track.
Combat use
On December 28, 1942, at the UZTM plant test site, a control machine from the December setting batch was tested. ACS covered 50 km. run and fired 40 shots. The tests of the vehicle were completed successfully, and the entire installation batch of the SU-122 was transferred to the Red Army. All 25 vehicles produced by this time were transferred to the self-propelled artillery training center. At the same time, at the end of December 1942, the first 2 self-propelled artillery regiments (1433 SAP and 1434 SAP) began to form, which were used on the Volkhov front. Each regiment consisted of two four-gun batteries armed with SU-122, as well as 16 SU-76 self-propelled guns, two light tanks or armored vehicles, trucks and cars, and 2 tractors.
The formed units fought their first battles on February 14-15, 1943 as part of a private offensive operation of the 54th Army in the Smerdyn area. During the battles, which lasted 4-6 days, self-propelled artillery regiments proved their effectiveness by destroying 47 bunkers, destroying 14 anti-tank guns, from 19 to 28 vehicles, suppressing 5 mortar batteries with their fire and destroying 4 enemy depots. The proposed tactics of using self-propelled guns also fully justified themselves. The SU-122 self-propelled guns moved at a distance of 400-600 meters behind the attacking tanks, suppressing the detected firing points with fire, mainly firing from stops. If necessary, self-propelled guns could be used to repel enemy counterattacks, acting as traditional howitzer artillery.
However, it was not always possible to adhere to this tactic. So already in the battle on the Kursk Bulge, vehicles were often used in the first line of the offensive, often replacing conventional tanks in attacks. As a result, vehicles unsuitable for fighting in the first line (insufficient armor, lack of machine guns, narrow firing sector) suffered unjustifiably large losses. In the course of the Battle of Kursk, the Soviet command pinned high hopes on the SU-122 as an effective means of dealing with the new armored vehicles of the Wehrmacht, but the real successes of self-propelled guns in the fight against tanks were very modest, and the losses were significant.
The SU-122 took part in the 1446 SAP and in the notorious counterattack near Prokhorovka. As a result of misuse, of the 20 vehicles participating in the counterstrike, 11 were burned, and another 6 were knocked out. At the same time, counterpreparations played an important role in the defensive actions of units armed with the SU-122 self-propelled guns - firing from closed positions at distant targets - clusters of enemy equipment and infantry. One way or another, the Battle of Kursk became the site of their most widespread use. Already in August 1943, they began to be replaced by new SU-85 vehicles, which belonged to the class of tank destroyers.
Performance characteristics: SU-122
Weight: 29.6 tons.
Dimensions:
Length 6, 95 m, width 3, 0 m, height 2, 15 m.
Crew: 5 people.
Reservation: from 15 to 45 mm.
Armament: 122 mm M-30S howitzer
Ammunition: 40 rounds
Engine: twelve-cylinder V-shaped diesel engine V-2-34 with a capacity of 500 hp.
Maximum speed: on the highway - 55 km / h, on rough terrain - 20 km / h
Progress in store: on the highway - 400 km.
