M163 VADS

M163 VADS
A U.S. Army M163 from the 24th Infantry Division at the National Training Center in November 1988.
Type	Self-propelled anti-aircraft gun
Place of origin	United States of America
Service history
In service	1968–present
Used by	United States of America, NATO
Wars	Vietnam War Western Sahara War 1982 Lebanon War Invasion of Panama Persian Gulf War
Specifications
Weight	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
Main armament	M168 General Dynamics 20 mm Vulcan Gatling 1,100 rounds
Secondary armament	None/crew small arms
Engine	General Motors 6V53, 6-cylinder two-stroke diesel 212 hp (158 kW)
Suspension	torsion bar, 5 road wheels
Operational range	480 km (300 mi)
Speed	64 km/h (40 mph)

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.

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.

The gun fires at 3,000 rounds per minute in short bursts of 10, 30, 60, or 100 rounds, or it can fire in continuous fire mode at a rate of 1,000 rounds per minute. A linkless feed system is used.

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) and a higher rate of fire, the M163 had a higher muzzle velocity 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.

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 even sank a PDF Vosper PT boat. The last combat action the VADS participated in was Operation Desert Storm.