M163 VADS
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 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 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. Performance. The M163 had a fairly limited range from the start. Its 20x102mm round gave it a low effective range of only , and its standard air-defense load  of HEI-T rounds would self-destruct at approximately , 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 (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 20x102  mm caliber remained. In 1988, the fourth crewmember 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 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 . Ammunition. While a large number of 20x102 mm 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. 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).