M163 VADS


The M163 Vulcan Air Defense System is a self-propelled anti-aircraft gun 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.

Technical description

The weapon is mounted on a modified M113 vehicle. 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.

Performance

The M163 had a fairly limited range from the start. Its 20x102mm round gave it a low effective range of only 1,200 meters, and its standard air-defense load of HEI-T rounds would self-destruct at approximately 1800 meters, a hard limit on range. Additionally, the radar was a range-only set incapable of finding 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 patrol 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, but that system was canceled due to cost overruns, technical problems and generally poor performance.
In 1984 the improved PIVADS system was introduced, providing improvements in the ease of use and accuracy of fire, but the limitations of the 20x102mm caliber remained. In 1988, the fourth crewmemember was issued a Stinger launcher and two rounds
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 20mm 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.

Ammunition

While a large number of 20x102mm round have been developed, not all were issued to M163 units. M246 HEI-T-SD was developed alongside the system and was the primary anti-air round, with M56 HEI being used for ground support. PIVADS units could use Mk 149 APDS rounds, which greatly increase maximum effective range due to their higher velocity and lack of a self-destruct. M940 may have been issued for use prior to withdrawal from service, though sources are unclear.
DesignationTypeProjectile Weight Bursting charge Muzzle Velocity Description
M56A3/A4HEI1029 g HE and 1.5 g incendiary1,030Nose fuzed round, no tracer.
M246/A1HEI-T-SD1028.0 g HE1,030M56 series derived tracer round, M246 using the same loading as M56A3 and M246A1 being derived from M56A4. Tracer burnout triggers the self-destruct after 3-7 seconds of flight time, roughly 1800 meters
M940MPT-SD1059 g A-4/RDX/wax1,050Multi-purpose fuzeless round for ground-based air defence, naval and helicopter applications. The HE charge is initiated by the incendiary charge on the nose on impact. Self-destruct due to tracer burn-through. Penetration: 12.5mm RHA at 0-degree impact at 518 m range, 6.3mm at 60 degrees and 940 m.
Mk 149APDSprojectile: 93 penetrator 70none1,120Spin-stabilized finless sub-caliber round with a 12mm depleted uranium penetrator. Penetration: 23mm armor at 45 degrees at 1,000 meters and 19mm at 45 degrees at 2,000m
M55TPnone1,030Inert training round based on M53 round
M220TP-Tnone1,030M55 training round with tracer, 1.9 second burn

Specifications

In the Israeli Air Defense Command the "Hovet" scored 3 shoot-downs, including the first shoot-down of a jet warplane 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 and Operation Defensive Shield.

Operators

Current operators