Already in November 1941, the Soviet Union joined the Lend-Lease program, according to which the United States supplied its allies with military equipment, ammunition, strategic materials for the military industry, medicines, food and other list of military goods. As part of the implementation of this program, the USSR also received armored vehicles, initially from Great Britain, then from the United States, for example, until 1945, Soviet troops received 3664 Sherman tanks of various modifications. But among the armored vehicles supplied to the Red Army, there were much rarer vehicles, such specific samples rightly include the T48 anti-tank self-propelled gun based on the M3 half-track armored personnel carrier.
Initially, this self-propelled gun was created in the United States by order of the British military, and was immediately intended for supplies under the Lend-Lease program. From December 1942 to May 1943, 962 T48 anti-tank self-propelled guns left the workshop of the Diamond T Motor Car Company. By this time, the British military had lost interest in the installation, and the USSR agreed to supply this vehicle, becoming the largest operator of the T48 tank destroyer, which received a new index SU-57. In total, the Soviet Union received 650 self-propelled guns of this type, the machines were actively used by the Soviet troops both as part of separate self-propelled artillery brigades and motorcycle battalions and armored reconnaissance companies.
Т48 from idea to implementation
Already at the very beginning of World War II, a mixed British-American arms commission began work in the United States. The task of the commission was to draw up a program for the development, design and release of various samples and types of military equipment. One of these samples was the 57-mm self-propelled gun based on the chassis of the M3 half-track armored personnel carrier common in the American army. Based on the M2 and M3 armored personnel carriers, American designers have designed a large number of self-propelled anti-aircraft guns, self-propelled guns with various artillery weapons, as well as self-propelled mortars. Some of them were produced by the American industry in fairly large batches, a vehicle based on half-track armored personnel carriers was adopted by the US Army and the armies of the countries of the anti-Hitler coalition allies.
The British military liked the possibility of using the chassis of an armored personnel carrier as a base for various types of weapons. They showed interest in creating a tank destroyer based on the M3, which would be armed with the British QF 6-pounder anti-tank gun. This British 57-mm anti-tank gun was actively used during the Second World War both on a wheeled carriage and as the main armament of armored vehicles and tanks of the British army. The debut of the gun took place in North Africa, it happened during the fighting in April 1942. The gun was also appreciated by the Americans, who adopted the British cannon, slightly modernizing the 57-mm gun, in the US Army the artillery system was designated M1.
An armor-piercing projectile of the specified gun from a distance of 900 meters pierced up to 73 mm of armor steel located at an inclination of 60 degrees. For 1942, these were acceptable numbers, but with the advent of new German tanks and the strengthening of the frontal armor of existing combat vehicles, the effectiveness of the 57-mm British anti-tank gun only declined. The choice of this particular weapon for installation on the M3 armored personnel carrier was due to the fact that the British wanted to obtain equipment that would be comparable in armament with their own, for example, the tanks "Valentine" and "Churchill". It was the gun that was the main and only armament of the anti-tank self-propelled gun on the chassis of a half-track armored personnel carrier, but already in the combat parts of the vehicle, it could also be equipped with machine guns for self-defense.
The first copy of the new anti-tank self-propelled gun arrived for the test program at the Aberdeen Proving Ground in April 1942. Armed with an adapted version of the British 6-pounder (57-mm) cannon, the armored vehicle received the designation T48 - 57 mm Gun Motor Carriage. Already in October 1942, the American order for a new self-propelled gun was canceled, the United States drew attention to new artillery systems of 75 mm caliber and tracked self-propelled guns. At the same time, the release of the new ACS under the British order continued, and mass production was launched in December 1942. The machines were assembled by the Diamond T Motor Company. However, by 1943, the British also lost interest in the new self-propelled gun, who realized that it was ineffective against the newest German medium and heavy tanks, moreover, in the UK they developed a new 17-pound cannon (76, 2-mm) QF 17 pounder, which became the best anti-tank weapon of the allies, having received an armor-piercing sub-caliber projectile with a detachable pallet.
As a result, the newly developed self-propelled gun turned out to be unnecessary for the main customers, the British received only 30 T48 vehicles, and the Americans limited themselves to buying one anti-tank self-propelled gun at all, they simply converted another 282 self-propelled guns back into M3A1 armored personnel carriers. But the remaining 650 units found refuge in the USSR, the Soviet military showed interest in this vehicle and ordered it as part of Lend-Lease deliveries, 241 vehicles arrived in the Soviet Union in 1943, another 409 in 1944. Moreover, only in the USSR, this anti-tank self-propelled gun was used for its intended purpose until the end of hostilities.
Design features of ACS T48
The layout and appearance of the American T48 SPG were traditional for vehicles based on such a base. Similar combat vehicles were in the arsenal of the German army. The Germans also equipped their Sd Kfz 251 half-track armored personnel carriers, known as the "Hanomag", with artillery systems of various calibers: 37-mm anti-tank guns, short-barreled 75-mm guns, and by the end of the war, and 75-mm long-barreled guns. Perhaps, having become acquainted with similar combat vehicles at the front, the Soviet military decided to get their own analogue, which led to the supply of 650 anti-tank self-propelled guns from the United States. In the Soviet Union, the vehicle received a new designation SU-57. It is worth noting that the USSR did not produce its own armored personnel carriers at all, therefore, such equipment as a whole was of great interest to the Red Army.
The layout of the anti-tank self-propelled gun, built on the chassis of a half-track armored personnel carrier, could be called classic. The hull of the self-propelled unit was distinguished by its simplicity of shapes and lines, the box-shaped structure with vertically arranged sides and stern walls was assembled using armor plates mounted on the frame from the corners. In the manufacture of the T48 anti-tank self-propelled gun, units of commercial trucks were widely used, mainly in the controls and in the transmission. In the front of the hull there was an engine hidden under an armored hood, behind it was the driver's cab. At the same time, the American designers borrowed the bonnet and the cockpit from the Scout Car M3A1 wheeled reconnaissance armored personnel carrier, which was supplied to the USSR and became the most massive armored personnel carrier of the Red Army during the Second World War.
The self-propelled hull was open from above and was distinguished by bulletproof armor, the thickness of the armor of the frontal hull plates reached 13 mm, in general, armor plates up to 6.5 mm thick were used in the design of the combat vehicle. In an open body, a 57-mm American M1 anti-tank gun was installed, which received a semi-automatic vertical wedge breech. The gun was installed on a T-5 machine, which was placed in the front of the hull just behind the control compartment. The gun was installed in a shelter covered from above from precipitation with a box-shaped shield, which protected the crew from bullets and shell fragments, the ammunition carried was 99 shells. The gun was distinguished by excellent horizontal guidance angles - 56 degrees, the vertical guidance angles of the gun ranged from -5 to +16 degrees. Three types of unitary rounds were used for firing from a 57-mm cannon: two armor-piercing (blunt-headed tracer and sharp-headed tracer) projectiles and a fragmentation grenade. At a distance of 500 meters, the gun allowed the crew to penetrate up to 81 mm of armor (at a meeting angle of 60 degrees).
The real heart of the self-propelled unit can be called the carburetor 6-cylinder engine White 160AX, which developed 147 hp, some of the cars were equipped with a slightly weaker engine - International RED-450-B, which developed 141 hp. Weak firepower and lack of armor were compensated by good mobility and speed. With a combat weight of about 8 tons, such an engine provided the vehicle with a power density of 17.1 hp. per ton. When driving on the highway, the T48 ACS accelerated to a speed of 72 km / h, the self-propelled gun's range was estimated at 320 km.
The front wheels of the self-propelled unit were steerable. For each side, the tracked propeller of the Lend-Lease self-propelled gun consisted of four double rubberized road wheels, the rollers were combined in pairs into two balance bogies. On the part of the self-propelled guns in the front of the hull there was a single-drum winch. At the same time, on some combat vehicles, the winch was changed to a buffer drum with a diameter of 310 mm. With such a device, the permeability of the ACS increased, the presence of a drum facilitated the process of overcoming scarps, ditches and trenches up to 1, 8 meters wide.
Features of the combat use of the SU-57
The half-track chassis and low weight provided the anti-tank self-propelled gun with good cross-country ability even on soft soils and snow. At the same time, the self-propelled gun predictably lost controllability. When turning the front wheels, the combat vehicle was not always ready to get to the required direction of movement. In fairness, it should be noted that similar shortcomings were inherent in German half-track armored personnel carriers. An open clash with enemy tanks left the Lend-Lease T48 self-propelled guns almost no chance of success. The use of these ACS from ambushes and from previously fortified positions was considered effective. At the same time, approximately for such actions on the battlefield, a new combat vehicle was originally created.
By 1943, the 57mm gun was in trouble with the new German Tiger and Panther tanks. At the same time, it pierced the frontal armor of medium German tanks Pz. IV of modifications G and H, it was possible to hit the Tiger or even the Ferdinand self-propelled gun on the sides of the hull. From a distance of 200 meters it was possible to try to hit the "Tiger" or "Panther" directly in the forehead, but with such actions without a well-prepared and disguised position - it was a one-way ticket. It can be noted that with certain restrictions, often very significant, the self-propelled gun still coped with its duties, actively participating in the battles on the Eastern Front.
If the armor penetration made it possible to hit the enemy's equipment, albeit with a large number of restrictions, then the effect of the 57-mm gun on the infantry and field fortifications was very weak. Such a weapon was not suitable for the destruction of prepared defense zones and fortifications. The power of 57-mm high-explosive fragmentation ammunition was clearly insufficient. The high-explosive fragmentation shot of such a gun weighed only 3.3 kg, and the mass of the explosive was only 45 grams.
The designated SU-57 Lend-Lease anti-tank self-propelled guns were widely used as part of three separate self-propelled artillery brigades, each of which had 60-65 combat vehicles of this type. SU-57 was a standard weapon for the 16th, 19th and 22nd (later became the 70th Guards) self-propelled artillery brigades, which fought as part of the 3rd, 1st and 4th Guards Tank Armies, respectively … In the Red Army, American self-propelled guns were also used in batteries and sub-divisions, in this case they were included in motorcycle battalions and separate reconnaissance companies on armored vehicles. In such units, the T48 self-propelled guns were used especially effectively, acting in their direct role - a half-track armored personnel carrier with a reinforced armament complex.
