ASU-57


The ASU-57 was a small, lightly constructed Soviet assault gun specifically designed for use by Soviet airborne divisions. From 1960 onwards, it was gradually phased out in favour of the ASU-85.

Development history

The task to develop a lightweight assault gun for the airborne troops was given to two design bureaus, Astrov in Mytishchi and Kravtsev in Moscow. Nikolaj Astrov's OKB-40 designed the ASU-76, based on components of the T-70 light tank and the SU-76 assault gun, and armed with the new 76 mm gun D-56T. The ASU-76 turned out to be too heavy, even though the armour was only 3 mm thick, and the project was cancelled. Anatoly Kravtsev's team came up with the similar, amphibious K-73. This vehicle was armed with Charnko's 57 mm anti-tank gun Ch-51 and was even more thinly armoured than the ASU-76. This project too was shelved.
In 1949, Astrov was instructed to continue with his project, but with reduced weight and with the Ch-51 gun as the main armament instead of the D-56T, since it offered better anti-tank performance. The redesigned Ob.572 was developed simultaneously with the Ob.561 light artillery tractor. After successfully passing the various test phases in 1949, it was accepted for series production from 1951 as the ASU-57.

Design

Armament

The ASU-57 was designed to be a lightweight assault gun that could be air-dropped out of the An-12 transport plane which was the standard cargo aircraft of the Soviet military at the time and deployed by rocket-assisted parachute along with the troops. It was lightly armored and armed with a 57 mm gun Ch-51, a development of the World War II ZIS-2 but with some similarities to the Ch-26. From 1954, an improved 57 mm gun Ch-51M with a much shorter double-baffle muzzle brake was fitted. The gun fired the standard caliber 57x480R ammunition of the ZIS-2 anti-tank gun, such as the BR-271 series and the O-271U, of which it had 30 on board, stored in various ammunition racks located at the rear of the vehicle and in easy reach of the loader, who sat facing backwards. The ASU-57 was also able to be fitted with an optional 7.62 mm DTM with 2500 rounds or 12.7 mm DShK machine gun.

Propulsion

The ASU-57's M-20E4 engine was taken from the GAZ-M-20 "Pobeda" civilian car and featured 50 hp of power. The engine was located on the left side of the transmission, which was located at the front of the vehicle and connected to frontal sprocket wheels driving tracks with four rubberised roadwheels on each side, with the last one acting as an idler wheel. The ASU-57 could reach a maximum speed of 45 km/h and had a 250 km range.

Protection

Designed to be as light as possible, the ASU-57 featured very limited armour in the form of aluminium plates that were a maximum of 6 mm thick at the front of the vehicle that was either bolted or welded on. The armour was only intended to resist rifle-calibre bullets fired by infantry and could be defeated easily by heavy machine guns such as the 12.7 mm M2 Browning. The top of the tank was completely open and thus exposed the crew to both the elements and enemy fire, especially in the form of grenades. If a crew stood up completely in the tank, their heads would be in view. Rather, the ASU-57 was intended to use its small size and mobility to avoid enemy fire. The open topped-nature of the vehicle also facilitated good vision and situational awareness for the crew, as well as easy access into and out of the tank.

Operational history

The ASU-57 was a successful design that saw service with Soviet airborne divisions for around 20 years before being replaced by the ASU-85. During its years of operation, 54 vehicles would have been assigned to each airborne division. One main drawback was the vehicle's welded aluminum hull, which offered little protection for the crew. However the vehicle gave lightly armed airborne troops mobile artillery support on the battlefield. Every vehicle was equipped with a 10RT-12 radio and a TPU-47 intercom system. Late-production models replaced these with the R-113 and R-120 respectively, and also had a TVN-2 night vision device for the driver.
The ASU-57 became the first successful Soviet airborne tank, overcoming failings in previous Soviet concepts that had stemmed from the 1930s. When the ASU-57 was introduced, every airborne division acquired 54 vehicles each, however by the turn of the 1960s, the ASU-57s only numbered 245 in service. It was realised that the armament of the main gun, a WWII-derived design, was vastly obsolete, especially when compared to NATO-equivalents such as the M40 recoilless rifle. The ASU-57 saw its first major deployment during Dniepr, a 1967 military exercise performed by the 76th VDD. In the following year, in 1968, ASU-57s saw its first combat-action during the Warsaw Pact-invasion of Czechoslovakia, with several vehicles used by the USSR. The ASU-57 was gradually supplanted and replaced by the heavier ASU-85, which featured a fully enclosed casemate design with a vastly superior 85 mm main gun.
In foreign military service, 20 ASU-57s saw service with the East German military, while 200 were given to North Korea. ASU-57s were also supplied to Egyptian forces, being used in the Six-Day War against Israel in 1967. Several dozen ASU-57s were sent to Ethiopia as well, were they took part in the Ogaden War with Somalia in November 1977, where ASU-57s were used in battles around Areva and Jijiga, assisting friendly forces during the battle, where notably, Mi-6 helicopters dropped at least several ASU-57s behind the Somali frontlines.

Variants

Former operators