The ZSU-23-4 "Shilka" is a lightly armoured, self propelled, radar guided anti-aircraft weapon system (SPAAG). ZSU stands for Zenitnaya Samokhodnaya Ustanovka, "anti-aircraft self-propelled system". It is named after the Russian Shilka River. NATO reporting name is "Awl" (probably as a result of confusion or association with the Russian word Shilo for "awl").

The system was developed by the Soviet Union in the 1960s and deployed to the Red Army from 1965. The Soviet Union developed modified versions from 1968 (-4V), 1972 (-4V1), and 1977 (-4M). The system was also supplied to Warsaw Pact nations and other states. Soviet successor states continue to manufacture and supply the system, notably the Ukrainian 4M4 and the Belarus 4M5. It features considerable accuracy and a fairly high rate of fire. It is seen as a major threat towards aircraft that fly at low altitude, especially for helicopters, for its radar provides for accurate positioning of fire.

The system saw active service in the Six-Day War (1967) and other Israeli-Arab conflicts, the First Gulf War (1990), and probably in the various Indo-Pakistan clashes.

Based on the chassis of the PT-76 light tank, the system mounts an armoured turret holding four liquid-cooled AZP-85 23 mm cannons linked to a RPK-2 "Gun Dish" 30 mm Radar. Post-Soviet versions can be fitted with a different gun (twin 30 mm 2A38M) and different radar. The vehicle weighs 20.5 metric tonnes, has a range of 450 km and a top speed of 50 km/h. Additional firepower can be supplied by a roof-mounted pod of six short-range SA-18 SAMs, or side mounted SA-16s. The guns have an effective range of 2.5 km and are useful against the slower low-flying aircraft and also lightly protected ground targets. The crew numbers four: driver, commander, and two radar personnel - gunner and ranger.

Soviet doctrine supplied the vehicle in a platoon of four to support MI or tank regiments in conjunction with medium-range SA-6 and short-range SA-9 teams. The system is very vulnerable to enemy fire, the armour is thin (maximum of 10 mm) and the exposed suspension, wheels, track, radar, and gun barrels can be easily damaged. Shilka units are typically placed near the forward-edge of battle-area (FEBA) but behind the main force.

Problems

One of the unpopular features of the Shilka is that should the water-coolant fail to quickly cool the system down, when the gunner lets go of the fire button, the cannons will continue to cook off ammunition.

History

The first Soviet self propelled anti aircraft gun (SPAAG), the ZSU-57-2, was based on caputured Nazi technology. Armed with two 57mm cannons, it was aimed optically using a basic tracking and lead calculating system. It was soon seen that the ZSU-57-2 was failure, for it was ineffective with the small amount of large rounds that it carried, inaccurate, and had limited mobility. A breakthrough came for Soviet SPAAG when the ZPU series of machine guns emerged. These were 14.5mm heavy machine guns that were put on a towed mount for stationary, point air-defense. The 23mm version of this weapon system was known as the ZU-23-2, a towed mount of two 23mm cannons.

In 1965, the Shilka was brought into service. It combined the proven Gun Dish radar, and the PT-76 light amphibious recon chassis. Finally, high mobility was coupled with the appropriate firepower. The ZSU-23-4 outclassed all NATO anti-aircraft guns at the time, and was widely fielded throughout the Warsaw Pact.

Detail

Each water-cooled 23mm cannon has a cyclic rate of 1,000 rounds per minute for a combined rate of fire of 4000 rounds per minute. To prevent overheating, the rate of fire is reduced to 50 round bursts per gun, and thus limits the Shilka's rate of fire to 200 rounds per minute. The turret is fully stabilised and capable of firing on-the-move. It has an elevation from -4° to +85°.

High-explosive-incindiary and armor-piercing incindiary rounds are fired. They can be fired to a maximum horizontal range of 7 km (4.3 miles), and a vertical range of 5.1 km (3.2 miles). The effective anti-aircraft range is around 2-2.5 km (1.3-1.6 miles). In attacking targets on the ground, its effective range is 2 km (1.3 miles).

The "Gun Dish" radar operates in the Ku band, and can pick up aircraft 20 km (12.5 miles) away. It has excellent target-tracking capability and is relatively hard to detect. Under 60 m (200 ft) of altitude however, the radar picks up a lot of false returns (ground clutter ). Regardless, pilots consider the Shilka to be an extremely dangerous weapons system. It is either avoided completely or engaged first.

Versions

• 1964: ZSU-23-4 - pre-production and then initial production models.
• 1968: ZSU-23-4V - minor modifications.
• 1972: ZSU-23-4V1 - more minor modifications.
• 1977: ZSU-23-4M - one extra ammunition panier on turret exterior (now three), added an armoured cover for the guns, upgraded fire-control computer to digital, "Gun Dish" radar can operate independently in search mode rather than only slaved to the guns.

External links

• Federation of American Scientists page
• GulfLINK: Soviet air defence vehicles