The M163 Vulcan Air Defense System (VADS) is a self-propelled anti-aircraft gun (SPAAG) that was used by the United States Army. The M168 gun is a variant of the General Dynamics 20 mm M61 Vulcan rotary cannon, the standard cannon in most U.S. combat aircraft since the 1960s, mounted on either an armored vehicle or a trailer.
A U.S. Army M163 from the 24th Infantry Division at the Fort Irwin National Training Center in November 1988
|Type||Self-propelled anti-aircraft gun|
|Place of origin||United States|
|Used by||United States, NATO|
Western Sahara War
1982 Lebanon War
Invasion of Panama
Persian Gulf War
|Mass||27,542 pounds (12,493 kg) (combat weight)|
|Length||191.5 inches (4.86 m)|
|Width||112.4 inches (2.85 m)|
|Height||115 inches (2.9 m)|
|Crew||4 (commander, gunner, loader, driver)|
|Armor||Rolled 5083/5086 H32 aluminium, 29-45|
|M168 General Dynamics 20 mm M61 Vulcan Rotary cannon|
|None/crew small arms|
|Engine||General Motors 6V53, 6-cylinder two-stroke diesel|
212 hp (158 kW)
|Suspension||torsion bar, 5 road wheels|
|480 km (300 mi)|
|Speed||64 km/h (40 mph)|
The weapon is mounted on a modified M113 vehicle (the M741 carrier). The system was designed to complement the M48 Chaparral missile system. The M163 uses a small, range-only radar, the AN/VPS-2, and an M61 optical lead-calculating sight. The system is suitable for night operations with the use of AN/PVS series night vision sights that can be mounted to the right side of the primary sight.
From the beginning, the main drawback of the M163 was its small caliber and lightweight shells, which limited its effective range. Early M50 series ammunition exacerbated the situation, but the M163 was still comparable to the contemporary Soviet ZSU-23-4; although the Russian ZSU fired a larger shell (23 mm rather than 20 mm) but had a lower rate of fire, the M163 had a higher muzzle velocity and higher rate of fire providing a flatter trajectory, shorter time of flight and thus better accuracy.
Unlike the ZSU the M163 has no search radar and has limited engagement capability against aircraft at night. The M163 gunner is exposed in the open turret, whereas in the ZSU-23-4 the gunner is in a fully enclosed armored turret; this gives the M163 gunner much better situational awareness and field of view at the cost of losing protection against rifle-caliber weapons and shell fragments. This is important, especially since the M163 has no search radar. The issue is that since it only possesses a basic rangefinding radar, it relies on the crew to spot the target and lock on to it, as there is no active system to detect incoming targets.
In US and Israeli service, the VADS has rarely been needed in its intended purpose of providing defense against aerial threats—consequently, the Vulcan gun system was in use throughout the late 1980s and early 1990s primarily as a ground support weapon. For example, VADS guns were used to support American ground assault troops in Panama in 1989 during Operation Just Cause. One Vulcan of B Battery, 2/62 ADA sank a PDF Vosper PT boat. The last combat action the VADS participated in was Operation Desert Storm.
Upgrades and replacement
In order to provide effective battlefield air defense against helicopters equipped with anti-tank missiles that could be fired accurately from ranges of several kilometers, the VADS was slated to be replaced by the M247 Sergeant York DIVADS (Divisional Air Defense System), but that system was canceled due to cost overruns, technical problems and generally poor performance.
In 1984 the improved PIVADS (Product-Improved VADS) system was introduced, providing improvements in the ease of use and accuracy of fire, but the limitations of the 20x102mm caliber remained. Also, the radar remained a range-only device. In the late 1980s modifications to the Vulcan through the addition of an interior and an exterior rack designed to carry Stinger missiles for dismounted firing were added in order to extend the life cycle of the system.
Eventually, the M163 was replaced in US service by the M1097 Avenger and the M6 Linebacker, an M2 Bradley with FIM-92 Stinger missiles instead of the standard TOW anti-tank guided missiles: the Stinger missile providing the necessary range to deal with helicopters with anti-tank missiles far out-ranging the 20 mm gun, as well as considerably extending the reach against fixed-wing targets. The final US Army VADS equipped unit at Fort Riley Kansas completed turn in of its Vulcans in 1994.
A wide variety of ammunition has been designed for the 20×102 caliber of the M168 six-barrel Gatling gun. Main types of combat rounds are listed in the table below; for comparison purposes, the table includes also the PGU-28 round used in M61 Vulcan aircraft cannon and the Mk149 naval anti-missile APDS rounds, although these are not normally used in land-based air defense guns.
- Armour layout:
- front: 38 mm
- sides: 45 mm to 32 mm
- rear/top: 38 mm
- bottom: 29 mm
- M168 gun on the M163:
- M163;M163A1. Changes to gun mount and vehicle to bring it in line with the M113A1. The resulting carrier vehicle was designated M741A1.
- M163A2. Powertrain changes to bring it in line with the M113A2. The resulting carrier vehicle was designated M741A2.
- M163 PIVADS (1984). Accuracy and workload improvements developed by Lockheed Electronics Company including a digital microprocessor, director sight and low backlash azimuth drive system. The PIVADS used the M741A1 carrier vehicle, and the improvements were carried over to the M163A2.
- M167. Towed version of the turret. Prime mover was the Gama Goat until 1989 when the Humvee replaced it.
- Machbet. Israeli upgraded version equipped with 4-tube FIM-92 Stinger pod, upgraded tracking system and the ability to share information with local high-power radar.
History of service
In the Israeli Air Defense Command the "Hovet" (the Israeli designation to the M163 VADS) scored 3 shoot-downs, including the first shoot-down of a jet warplane (a Syrian MiG-21 fighter jet) by the M163 VADS, during Operation Peace for Galilee in 1982. The Israel Defense Forces used the M163 Hovet also for fire support during urban warfare in Operation Peace for Galilee (1982) and Operation Defensive Shield (2002).
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