Dictionary and translator for handheld
New : sensagent is now available on your handheld
A windows (pop-into) of information (full-content of Sensagent) triggered by double-clicking any word on your webpage. Give contextual explanation and translation from your sites !
With a SensagentBox, visitors to your site can access reliable information on over 5 million pages provided by Sensagent.com. Choose the design that fits your site.
Improve your site content
Add new content to your site from Sensagent by XML.
Crawl products or adds
Get XML access to reach the best products.
Index images and define metadata
Get XML access to fix the meaning of your metadata.
Please, email us to describe your idea.
Lettris is a curious tetris-clone game where all the bricks have the same square shape but different content. Each square carries a letter. To make squares disappear and save space for other squares you have to assemble English words (left, right, up, down) from the falling squares.
Boggle gives you 3 minutes to find as many words (3 letters or more) as you can in a grid of 16 letters. You can also try the grid of 16 letters. Letters must be adjacent and longer words score better. See if you can get into the grid Hall of Fame !
Change the target language to find translations.
Tips: browse the semantic fields (see From ideas to words) in two languages to learn more.
ZSU-23-4V at the Technical Museum in Togliatti, Russia
|Type||Self-propelled anti-aircraft gun|
|Place of origin||Soviet Union|
|Used by||See Operators|
|Wars||See Combat history|
|Manufacturer||Mytishchi Engineering Works (MMZ)|
|Number built||About 6,500|
|Height||2.576 m (3.572 m with elevated radar)|
|Crew||4 (commander, driver, gunner, radar operator)|
|Armor||welded steel, 9.2 mm turret, up to 15 mm hull|
|4 × 23 mm 2A7 autocannons (AZP-23 "Amur" quad automatic anti-aircraft gun), ammunition 2,000 rounds|
|Engine||V-6R, 6-cylinder 4-stroke airless-injection water-cooled 19.1 litre diesel
280 hp (209 kW) at 2,000 rpm
|Power/weight||14.7 hp/tonne (11.0 kW/tonne)|
|Suspension||individual torsion bar with hydraulic shock absorbers of 1st, 5th left and 6th right road wheels|
|Ground clearance||400 mm|
|Fuel capacity||515 l|
|450 km (road), 300 km (off-road)|
|Speed||50 km/h (road), 30 km/h (off-road)|
The ZSU-23-4 "Shilka" is a lightly armored, self-propelled, radar guided anti-aircraft weapon system (SPAAG). The acronym "ZSU" stands for Zenitnaya Samokhodnaya Ustanovka (Russian: Зенитная Самоходная Установка), meaning "anti-aircraft self-propelled mount"; the "23" signifies the bore diameter in millimeters; the "4" signifies the number of gun barrels. It is named after the Russian Shilka River. Polish soldiers nicknamed it maszyna do szycia (sewing machine) due to the sound of firing guns and because of the similarity of the name "Shilka" to the Russian word "шить" (Russian pronunciation: [ʂitʲ], meaning "to sew"). It is also referred to by its nickname of "Zeus".
The previous Soviet self-propelled anti-aircraft gun (SPAAG), the ZSU-57-2, was armed with two 57 mm autocannons; it was aimed optically using a basic tracking and lead calculating system. The ZSU-57-2 was not particularly successful despite its very powerful autocannons; it could only carry a relatively small amount of ammunition, was inaccurate as it lacked radar and could not fire while on the move.
The ZPU series armed with 14.5 mm heavy machine guns carried on a towed mount for stationary, point air defence had a much higher rate of fire. The 23 mm version of this weapon system was known as the ZU-23-2, a towed mount carrying two 23 mm cannons.
The development of the ZSU-23-4 "Shilka" began in 1957 along with ZSU-37-2 "Yenisei" and the vehicle was brought into service in 1965, replacing all ZSU-57-2s in air defense units toward the beginning of the 1970s. The ZSU-23-4 was intended for AA defense of military facilities, troops, and mechanized columns on the march. Initially, tank regiments should have had the anti-aircraft artillery battalion of "Shilka" (consisting of two batteries, four ZSU-23-4s in each). At the end of 1960s, one battery was equipped with ZSU-23-4s and the other with ZSU-57-2s. Motorized rifle and tank regiment standard anti-aircraft batteries consisted of two platoons later (one platoon was equipped with four ZSU-23-4s and another with four mobile surface-to-air missile systems 9K31 Strela-1 or 9K35 Strela-10). The ZSU-23-4 combined a proven radar system, the non-amphibious chassis based on GM-575 tracked vehicle, and four 23 mm autocannons. This delivered a highly effective combination of mobility with heavy firepower and considerable accuracy. The ZSU-23-4 outclassed all NATO anti-aircraft guns at the time, and it is still regarded as posing a major threat for low-flying fixed-wing aircraft and helicopters.
The system was widely fielded throughout the Warsaw Pact and among other pro-Soviet states. Around 2,500 ZSU-23-4s, of the total 6,500 produced, were exported to 23 countries. The Soviet Union's successor states continue to manufacture and supply variants of the ZSU-23-4, notably the Ukrainian "Donets" and Polish "Biala" variants.
ZSU-23-4 units saw active service in the Yom Kippur War (1973) and other Arab-Israeli conflicts, the Iran–Iraq War (1980–1988), and the First Gulf War (1990). During the 1973 Yom Kippur War, the system was particularly effective against the Israeli Air Force. Israeli pilots attempting to fly low in order to avoid SA-6 missiles were often shot down by ZSU-23-4s as in Operation Doogman 5. During the Soviet-Afghan War ZSU-23-4 units were used widely and to great effect against mujahideen positions in the mountains, the ZSU-23-4's guns being able to elevate much higher than the weapons on BMPs, BTRs, T-55s, or T-62s. They were also used to suppress defensive positions around the presidential palace during the initial coup in Kabul at the start of the Soviet-Afghan war. The Russian Army used the ZSU-23-4 for mountain combat in Chechnya.
The radar-guided ZSU-23-4 "Shilka" SPAAG, with its four 23 mm (0.90") autocannons, was a revolutionary SPAAG, proving to be an extremely effective weapon against enemy attack aircraft and helicopters under every weather and light condition. The ZSU-23-4 has a very high density, rate and accuracy of fire, as well as the capability for each of the four autocannons to fire its own type of projectile from separate belts. While it is technically possible that each cannon shoots different type of ammo, there were two types commonly used in late 1970s: OFZT incendiary fragmentation and BZT armour-piercing tracer, which were to be loaded in 3:1 ratio—three OFZT, then one BZT, every 10th BZT round equipped with so-called "copper remover" and marked. It was strongly recommended against shooting from a single barrel. The appearance of the "Shilka" caused significant changes in NATO tactics in aircraft use at low altitude over the battlefield.
Despite its present obsolescence as a modern short-range anti-aircraft weapon, the ZSU-23-4 is still deadly for enemy light armoured vehicles, infantry and firing points as an infantry-support vehicle. With its high rate of accurate fire, the ZSU-23-4 can even neutralize tanks by destroying their gun sights, radio antennas, or other vulnerable parts. ZSU-23-4s, especially late models, have excellent performance and good systems reliability.
Based on the GM-575 tracked vehicle chassis, which used components from the PT-76 light amphibious tank, the ZSU-23-4 mounts an armored turret holding four liquid-cooled 23 mm (0.9") 2A7 autocannons linked to an RPK-2 "Tobol" radar (NATO designator: "Gun Dish"). The vehicle weighs 19 tonnes (late modifications up to 21 tonnes), has a movement range of 450 km (280 mi) and a top speed of 50 km/h (31 mph). Additional firepower of late modifications can be supplied by a roof-mounted pod of six short-range SA-18 SAMs, or side mounted SA-16s.
The crew numbers four: driver, commander, gunner and radar operator. The driver's compartment is located in the nose part of the vehicle. The fighting compartment is in the center, and the engine compartment is in the rear part of the vehicle. The ZSU-23-4 provides minimal comfort for the crew. Whereas the driver's compartment has a good self-contained air pump with an electric heating system, other crew members suffer from cold in winter because the heating system of the fighting compartment, heated handrails and floor, is ineffective. It is hot inside the vehicle in summer.
The transmission consists of a multi-plate metal-contact main clutch, a manual gearbox with five forward gears, two planetary two-step steering gears with locking frictions and two final drive groups. The vehicle chassis has six single rubber tired road wheels, a rear drive sprocket with detachable sprocket rings (lantern-wheel gear) and one idler wheel per side. The first and fifth left, and sixth right road wheels have hydraulic shock absorbers. The track is 11.904 m long, 382 mm (15") wide and has 93 links.
Because of a large number of different pipes and tubes to detach during maintenance, the repair procedure for some of the vehicle's mechanisms is hard (for example, replacement or repair of a starter). The electric drive of an air outlet hatch of a gas turbine engine (part of the vehicle's electric power supply system) has an inconvenient location (at the bottom of the hull) which causes overheating and sometimes, jamming of the electric drive. On the other hand, the construction of the electric power supply system is very reliable. Changing the main engine oil and coolant is easy, as is replacement of fuel and oil filters, and sections of the air filter.
The ZSU-23-4 can cross vertical obstacles 0.7 m (2.3') high, trenches 2.5 m (8.2') wide, has a 1.0 m (3.3') fording depth and can climb 30° gradients. The ZSU-23-4 has good maneuverability and cross-country ability, but its diesel engine's power is insufficient for a vehicle of its weight. As a result, off-road acceleration capabilities are sub-par, and the vehicle lags behind MBTs and IFVs on up-hill terrain.
The ZSU-23-4 is equipped with an NBC system with an air filtration unit, fire-fighting equipment, TNA-2 navigational system, infrared vision device, R-123 radio set, R-124 intercom and electric power supply system consisting of a DGChM-1 single-shaft gas turbine engine (70 hp at 6,000 rpm) and a direct-current generator (which provides 27 V and 54 V direct current or 220 V 400 Hz alternate current).
Each water-cooled 23 mm 2A7 autocannon has a cyclic rate of 850–1,000 rounds per minute for a combined rate of fire of 3,400–4,000 rounds per minute. The welded turret has a race ring transplanted from a T-54 medium tank with a 1,840 mm (6') diameter. The 360° rotating turret is fully stabilised and capable of firing on the move. The turret rotation and autocannon elevation mechanisms provide very good speed and guidance accuracy. The hydraulically driven aiming mechanisms have been proven to be very reliable. Manual aim is used against ground targets. The quad automatic anti-aircraft gun AZP-23 "Amur" has a range of elevation from -4° to +85°. The GRAU designation for ZSU-23-4 turret with 23 mm (0.9") AZP-23 "Amur" quad automatic gun is 2A10. An armoured plate inside the turret protects crew members from fire and explosive gas during intense firing.
Ammunition capacity is 2,000 rounds stowed aboard (520 rounds per each upper autocannon and 480 rounds per each lower autocannon) loaded in 50-round or shorter belts.
The water-cooled 2A7 23mm guns of ZSU-23-4 fire the same 23×152 mmB caliber ammunition as the 2A14 guns of the twin-barrel ZU-23-2 towed gun. While the 23mm Volkov-Yartsev VYa-23 aircraft gun used in the Second World War era Il-2 Sturmovik also fired ammunition of same cartridge case dimensions, the rounds differed in loading and primer, and are thus not interchangeable with the post-war AA gun ammunition. Compared to the VYa and its ammunition, the air defence guns have slightly higher muzzle velocity, and explosive rounds also have slightly larger HE fillings. The VYa ammunition has brass cases, while 2A7/2A14 ammunition has steel cases.
Three main types of 23mm anti-aircraft ammunition were manufactured post-war: API-T, HEI and HEI-T. Additionally to the original Soviet rounds, a number of ammunition manufacturers have since begun to produce ammunition for what is still a widely used caliber; these include also new ammunition types such as sub-caliber armour-piercing rounds and frangible ammunition. The following table lists the main characteristics of some of the available 23×152 mmB ammunition used in 23mm AA guns:
|Designation||Type||Projectile Weight [g]||Bursting charge [g]||Muzzle Velocity [m/s]||Description|
|BZT||API||190||?||970||Blunt AP steel core, with incendiary charge inside windshield cap. Penetration 15 mm RHA at 100 m range and 30-degree impact angle, or 25mm at 400m and 0-degree impact. Tracer burn time 5 seconds.|
|OFZ||HE||184||19||980||HE fragmentation round with nose fuzes incorporating self-destruct mechanism.|
|OFZT||HE-T||188||13||980||HE fragmentation round with a reduced HE charge due to the space taken by the tracer; tracer burn time 5 seconds.</ref>|
|APDS-T||APDS-T||103||none||1220||A Polish sub-caliber armour-piercing round with tracer. Penetration 30 mm RHA at 100 m range and 30-degree impact angle (from perpendicular), tracer burn time >2.5 s.|
A typical loading of each ammunition belt contains 40 OFZT and 10 BZT rounds. They can be fired to a maximum horizontal range of 7 km (4.3 mi), and a vertical range of 5.1 km (3.2 mi). The effective vertical range is 1.5 km (0.93 mi) at a direct range to target of 2.5 km (1.6 mi) and target speed of 250 m/s (up to 500 m/s if a modern fire control system is used). The usual autocannon burst consists of 3–10 projectiles and target lead angle is calculated for each burst (fire without adjustment) by computer. In attacking targets on the ground, its effective range is around 2.5 km (1.6 mi). The short range of its 23 mm autocannons and relatively low explosive effect of its small-calibre projectiles mean it is less able to engage threats such as jet attack aircraft and cruise missiles than modern systems like the 9K22 Tunguska armed with more powerful 30 mm autocannons and integrated missile armaments. A special 23 mm round with composite projectiles was developed for a modern modification of SPAAG (ZSU-23-4M4) to be used against cruise missiles.
The RPK-2 "Tobol" a.k.a. 1RL33 radar operates in the J band and can detect aircraft up to 20 km (12 mi) away. It has excellent target tracking capability and is relatively hard to detect by the enemy. However, the radar picks up many false returns (ground clutter) under 60 m (200 ft) of altitude. The radar antenna is mounted on collapsible supports in the top rear of the turret. There is an optical alignment sight. The RPK-2 radar proved to have good protection against enemy passive electronic radar counter-measures. Nevertheless, the radar system of the ZSU-23-4 has a short detection range during target search, depending on weather conditions (mainly dependent on rain and snow conditions). It is hard to automatically track the target at ranges less than 7–8 km (4.3-5.0 mi) because of the high angular speed of the target at close distances. The radar needs to be reset quite often because of the unstable parameters of electronic cathode-ray tubes of the target selection system. The absence of an automatic laser range finder requires a skillful commander and gunner.
Early versions of the ZSU-23-4 sometimes had problems with "runaway guns": after prolonged periods of firing, the guns would get so hot that chambered rounds would "cook off" even if the operator was not pulling the trigger, discharging the weapon and chambering a new round, which would then also cook off, and continue to do so. This would sometimes continue until the entire belt of ammunition had been expended. Overheating barrels could jam and even break away from the vehicle. The problem resulted from a deficient cooling system and made the early ZSU-23-4s dangerous even to friendly troops standing nearby if this happened. Despite the fact that this seldom happened, Soviet operators learned to give these machines a wide berth.(Perrett 1987:100) It was not recommended to perform continuous fire (bursts longer than 15 seconds without pause) on earlier models until the problem with autocannon reliability and overheating during intense fire was solved on ZSU-23-4M (welded tubes of coolant outlet were replaced with flexible pipes). After the autocannon cooling system was improved, the autocannons became extremely reliable.
Soviet doctrine supplied the vehicle since 1965 in an anti-aircraft artillery battalion of two, four-vehicle platoons for anti-aircraft defence of motor rifle and tank regiments. At the end of the 1960s one platoon was equipped with ZSU-23-4 SPAAGs while another one was still equipped with ZSU-57-2 SPAAGs. ZSU-57-2 was completely replaced with ZSU-23-4 by the beginning of 1970s. In the 1970s, Soviet motor rifle and tank regiments were equipped with an anti-aircraft missile artillery battery consisting of two platoons, one equipped with four ZSU-23-4 SPAAGs and the other with four 9K31 Strela-1 (SA-9 Gaskin) or later with four 9K35 Strela-10 (SA-13 Gopher) short-range surface-to-air missile systems which cover the dead zones of 2K12 Kub (SA-6 Gainful) surface-to-air missile systems belonging to the divisional level. Since the 1980s Soviet motor rifle and tank regiments were equipped with an anti-aircraft artillery battalion of three batteries (one was equipped with ZSU-23-4 or 9K22 Tunguska SPAAGs, the second one was equipped with 9K35 Strela-10 (SA-13 Gopher) short-range surface-to-air missile systems and the third battery with 9K38 Igla man-portable surface-to-air missiles on IFVs or APCs.
The ZSU-23-4 is very vulnerable to enemy anti-tank missiles, cannons and heavy machine guns; the armour is thin (not exceeding 15 mm) and the exposed wheels, tracks, radar, and gun barrels can easily be damaged in combat. Firing positions of ZSU-23-4 SPAAGs are typically placed near the forward edge of the battle area (FEBA) but behind the main forces, usually 600–1000 m behind objectives when on the defensive or 400–600 m behind the leading tanks on the offensive. ZSU-23-4 SPAAGs are divided evenly along the troop columns on the march.
At first each ZSU-23-4 operated in combat autonomously, without target marking from regimental or divisional air defence. In 1978, the PPRU-1 (mobile reconnaissance and control post) was passed into service of the Soviet Army. The PPRU-1 ("Ovod-M-SV") vehicle is based on MT-LBu armoured tracked chassis and it was intended for control of motor rifle or tank regimental anti-aircraft unit equipped with ZSU-23-4 SPAAGs and 9K31 "Strela-1M" mobile surface-to-air missile systems. The PPRU-1 is equipped with "Luk-23" radar and an automatic fire control system associated with the divisional air defence system.
The guns are useful against low-flying aircraft and lightly protected ground targets. Due to its effectiveness against ground targets, ZSU-23-4s have been used in urban environments (e.g., Afghanistan, Abkhazia, Chechnya, Syria and Lebanon). This is primarily because the guns can elevate much higher than a tank or APC cannon, enabling armored units equipped with ZSU-23-4s to return fire against ambushes from above.
Apart from the Russian Army, a small number of ZSU-23-4 SPAAGs are still in use by the Russian Naval Infantry (specifically the 61st and 175th brigades of the Northern Fleet and the 336th brigade of the Baltic Fleet).
|Wikimedia Commons has media related to: ZSU-23-4 Shilka|