Chilling Adversary: Soviet ZSU-23X4

During the 1960s the Soviet Army was equipped with a range of surface-to-air missile types that were mounted on vehicles to provide mobile platforms, such as the SA-4 “Ganef”, SA-6 “Gainful” and SA-9 “Gaskin”. It was a trend copied by some Western countries such as France with its Crotale mounted on AMX-30 tank chassis. 

On Nov. 7, 1965 a surprise was sprung on Western observers watching a military parade in the Soviet Union when a new self-propelled anti-aircraft gun system was publicly revealed for the first time. The new ZSU-23X4, referred to as the “Shilka”, after the river of the same name, paraded along with the older ZSU-57-2 self-propelled anti-aircraft gun system, which had entered service in 1957 and was now showing its age.

Self-propelled anti-aircraft gun systems, SPAAGS, were nothing new. During WWII the German Army had used several designs, including the “Flakvierling” mounting four 2cm anti-aircraft guns. The American Army experimented with designs such as the T77E1 and the Canadian Army with the “Skink”, neither of which entered service. The Shilka, however, was something altogether different, being self-contained, armed with four 23mm cannons mounted in the turret capable of being guided onto the intended target by the vehicle’s on-board target acquisition and tracking radar system. 

Development of this new system had been delegated to the factories of the Ulyanovsk Mechanical Plant and Mytishchi Machine Building Plant in 1957, the same year that the ZSU-57-2 entered service. The ZSU-57-2, the figures referring to the caliber and numbers of weapons carried, lacked onboard radar, the guns had low rates of fire and a very limited amount of ammunition was carried on board. Such drawbacks severely hampered its operational capability and a replacement was required. The developing companies began work on the replacement project in 1957 and by 1960 had produced a working prototype. A series of field trials were conducted into 1964, during which time those points that required changes and modifications were identified. A second design was also being prepared, known as the ZSU-37-2 “Yenisei”, but with the appearance of what would become known as the ZSU-23-4 the Yenisei was dropped in 1962, having been worked on for almost 10 years with only two prototypes to show for it.

Finally, in 1964 series production began on the ZSU-23-4 Shilka with the first systems entering service in 1965. Over the next 18 years some 6,500 Shilkas would be produced before production was halted in 1982. As well as serving with the army of the Soviet Union, the system was used by other armies within the Warsaw Pact, including Bulgaria, the German Democratic Republic (the then East Germany) and Hungary. Overseas client states included the armies of Cuba, Somalia, Syria, Libya, North Korea and India. Its appearance made the Western NATO allies reconsider their aerial tactics and forced them to develop new battlefield practices and counter-measures, both electronically and pyrotechnical, in response to the threat.

The Shilka used a chassis based on the Gusenichnaya Mashina (GM) tracked series, as utilized on the PT-76 light amphibious tank, but fitted with a more powerful rear-mounted diesel engine. The road wheel layout remained the same as the PT-76, comprised of six road wheels with the idler wheel set to the front and the drive sprocket to the rear with torsion suspension and lacking return rollers. The hull was modified to take the new turret design, which was mounted centrally on the hull deck over the fighting compartment. A crew of four operated the vehicle: commander, driver, radar operator and gunner.

Looking down from above, the turret had a short, oblong shape with the long edges forming the sides. The turret was made from pressed steel panels with armor protection varying from 9.2mm to 15mm across the vehicle, including the hull. Viewed from the side the turret resembles a large, compressed cube but did not dominate the vehicle as with self-propelled guns. Into the turret was fitted the RPK-2 “Tobol” 1RL33 radar with the dish mounted externally to the rear and lowered when not in use. This system had a detection range of 12 miles and was capable of being used on the move, through results greatly improved when it was statically deployed.

The main armament, indeed the only armament, carried by the Shilka were four modified AZP 23mm cannons fitted in a quadruple arrangement mounted in the turret. These weapons were similar to the 23mm ZU cannons used as ground emplaced point defense system with twin barrels fitted to a pedestal mounting. The AZP-23 barrels were water-cooled and had a combined rate of fire between 800 and 1,000 rounds per minute. However, when engaging a target the rate of fire was kept to short bursts of 30 rounds per minute. This method of firing produced a distinctively audible signature which earned it the nickname of “Sewing Machine” from the troops.

The turret allowed for a full 360-degree traverse to keep tracking a target, and the guns could be elevated to +85 degrees and depressed to -4 degrees, which allowed ground targets. The cannon fired three different ammunition types: armor-piercing incendiary (API); High Explosive (HE) and High Explosive Tracer (HET). The weapon system had an effective range of over 4 miles firing in the horizontal and over 1.5 miles in the vertical, with 2,000 mixed rounds carried. Being an SPAAG, the Shilka could provide anti-aircraft defense to a convoy or deployed static to engage helicopters and slow-moving ground attack aircraft.

The Shilka has been deployed in many conflicts over the past 60 years. It was used by the Indian Army during the Indo-Pakistan War of 1971, by Egypt and Syria during the Yom Kippur War of 1973 and most recently by the Ukraine Army since 2022 following the invasion by Russia — which also deploys the same system. Most notably, though, it was used by the Russian Army during its incursion into Afghanistan between 1979 and 1989. 

The Shilka has been deployed in a variety of ways. In 1965, Russia used four vehicles in each platoon of two batteries of anti-aircraft artillery attached to either a motor rifle or tank regiment. By the 1980s, with more modern SPAAGS entering service and more anti-aircraft missiles, this arrangement was changed so that a battalion was formed around three batteries, of which only one was equipped with four Shilka. 

Despite its age, the Shilka remains in service around the globe, in some cases serving alongside more modern types of SPAAG such as the 2K22 “Tunguska”. Other examples have been upgraded with modernizing programs by various armies, such as the ZSU-23-4M-A1 “Rokach” developed by the Ukraine Army in 2017and currently being used against the invading Russian Army.

There are a few examples of the Shilka in private ownership, but more likely they are to be spotted in a museum such as that at Yad Ia-Shiryon in Israel or the Museum of Russian Military History. In the United Kingdom there are several examples on display at the Museum of Army Flying at Middle Wallop in Hampshire, the Muckleburgh Collection in Norfolk and the Tank Museum at Bovington in Dorset. These are joined by examples of SPAAGS developed by countries in response to the Shilka, such as the French AMX-13 DCA with twin 30mm guns and the West German Gepard with twin 35mm guns. 

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