The M163 VADS was a cold war mass produced self propelled anti-aircraft gun based on the M113 armored personal carrier. It entered service in the Vietnam war and stayed in service until the 1991 Gulf War, gradually replaced by the M2 Bradley and other systems. Called officially the Gun, Air Defense Artillery, Self-Propelled 20-mm, M163, was developed by Vulcan and primarily used by the United States Army, replacing the M42 Duster, it was declined into three variants and also used by Chile, Ecuador, Egypt, Iran, Israel, Jordan, Morocco, Portugal, Saudi Arabia, Thailand, and Tunisia.


Vulcan and Chaparral side by side

Development

Replacing the M42 Duster

The need for SPAAG went back to WW2 and was already provided with the M17 MGMC and other systems based on the M3 half track car. In Korea, a new vehicle was used, the M24 Chaffee based M19 GMC, and before the Vietnam war broke out, the M24 Duster based on the M41 Walker Bulldog light tank. This was still the primary SPAAG in the 1960s and was considered obsolete against modern Jets. Work started to to replace it with a more modern system, or rather two, one carrying missiles, and another with guns.

Yet organic army defense in the move needed an alternative with better firepower and visual guidance, complementary to a missile system with longer range. The M163 VADS was thus developed froma standard FMC M113 armoured personal carrier (APC) with the M168 gun, a variant of the GM 20 mm (0.79 in) M61A1 rotary cannon standard on most U.S. combat aircraft at the time. The carrier, a modified M113A1 vehicle was called the M741 carrier. The marriage was quickly developed in 1964-65 and tested in 1965, entering limited evaluation service in 1968. It was designed to complement the M48 Chaparral missile system, also developed from a modified FMC M113 platform, in rder to gain maximum commonality for a simple, leaner maintenance chain in the field.



The only issue with the new design is tht it was limited to good weather operations, something which was compatible with Vietnam weather conditions in most but the monsoon seasons. However it left to be desired if integrated in frontline NATO units in Germany where the weather was average most of the time. The M163 was still radar guided, but constrains of technology and weight had the small range-only AN/VPS-2 radar fitted, coupled with a M61 optical lead-calculating sight. The radar was just here to help following a target, but could search and scan an area for targets. If AN/PVS series night vision sights were added, it could be used by night, the IR sight being mounted to the right side of the primary sight.

Program Development

The M163 became a self propelled variant of the General Dynamics 20mm M61 rotary cannon, an ubiquitous system proven, mounted in most US aircraft since the 1960s. It was then used for air defense and a derivative was also later adopted by the USN and many other navies as the Phalanx system. This was for a very long time, the new standard mobile light anti-aircraft gun of the US Army. Its only limitation was the absence of night fire capabilities. Still, there was a serie of modifications to improve its reliability, availability, and maintainability (RAM) developed during the early 1970s by the US Army Armament Command (ARMCOM), in coordination with the Tank and Automotive Command (TACOM) and all contractors in the value chain.

Because of the large number modifications, the VADS gained the "Al" model configuration which became the production standard. In March 1975, AMC was pressed to improved the program and by June 1975, gained sole authority to field the draft technical manuals (TMs) for crew's accelerated application. With modification kits the upgrades could be done in the field through depot level contractor teams to accelerate upgrades.

The goal of the radar reliability product improvement program was to increase its mean-time-between-failure (MTBF), from 30 hours to 100 hours. During its test range (PIVT), it showed a 122 hours MTBF was possible if done right. But to achieve this, some 200 components were removed and replaced and some omitted or other sub-systems simplified and commonalized. Many improvements were also due to a renetting of internal RF cables and well as better suited electrolytic capacitors as well as operational amplifiers and RF filters. The blower motor inverter was also brand new and completed by a klystron power supply circuit. There were also new types of enclosure gaskets and radiate lens and a leaner power supply in general.

Thus improved M163 VULCAN air defense system was considered in Army studies as a Divisional Air Defense Gun, for heavy divisions, especially in a NATO context in Europe. The improvement still remained unfuned and instead, modification kits were developed by the manufacturers at their own expense. However only limited demonstrations were performed. The Congress added these to FY1981 in the DoD budget for a general upgrade in army air defense capabilities but limited to the airborne and air assault divisions. The program was also to include new ammunitions and better operability, tracking accuracy, and short reaction time.

Still, the DoD (Department of Defense) had concerns about the future of such system at the age of supersonic jets and agile short range missiles. Its effectiveness in the 1980s was seriously contemplated, and the Deputy Undersecretary of Defense for Research and Engineering declared it was in the end, only fit for "less intense air attack environment" that is in non-European theaters and asymetric theaters. The US Army Air Defense School still clinged to the system as well as the Army headquarters officials as long as it was financed by the Congress and lobbied to have the improvement program ported on the VULCAN.

Its adversaries were the Army's Training and Doctrine Command. They started that most of the time it provided a limited range, chance-based engagement probability value, with an overall doubtful increases in effectiveness. The Materiel Development and Readiness Command saw it at best as an interim system and the acquisition of PIVADS being against the development of a more modern and better suited lightweight air defense system.

In 1984, the "upgrade clan" won the PIVAD implementation, arguing the addition of a digital computer with range-only radar increased further its effectiveness and simplified operations. Also the manufacturers came up with a range of new ammunition such as the very effective armor piercing discarding sabot increasing its speed and impact despite a sub-caliber of 20 mm with a range ported to 2,600 meters (8,500 ft).

M163's Successor

Army efforts to replace the Vulcan on the other hand, ended in disaster. It was largely due to the absence of a real air threat in most encountered conflicts, Korea and Vietnam opposing the US combined forces to a rather asymetric, low tech force. Each time, mastery of the sky was acquired, and if contested over some areas (like north vietnam), neither the Chinese or NKA (in Korea) and neither the ARVN or North Vietnamese regulars were in any way shape of form able to pose a serious air threat that would have crippled the army movements. Air superiority only had been force decades lulling US forces into a false sense of security.

By the 1970s analysts based on intel reports reported that in the NATO, western European theater a mid to high intensity conflict with USSR woild mean mechanichally due to clear superiority in material from the Warsaw pact, moments were the ground forces would be subjected to air parity or even even air superiority over parts of the battlefield. In this non-linear combat configuration there was no certainty air defence would be over any armour formation inthe field at any moment. And due to the possible absence of air support and defence, an organic way to defend land assets was srill necessary, and a good one, ayered, to face multiple threats deployed by the USSR in the air, betrween new combat helicopters and dedicated ground attack aircraft.

The US Army knew this deficiency in that forward area air defense and from 1970 to the late 1980s there was the interim Vulcan an nothing else. The Army initiated separate studies from 1972 to 1976 and each time came down to the same conclusion a new gun was required. In 1984 many M163 were still around, but now upgraded under the M163 PIVADS program. This was the result of the abject failure of the M247 Sergeant York known by the acronym DIVAD (Division Air Defence gun). It was developed as a state-of-the-art mobile Anti-Aircraft gun system to replace two systems, the M163 20mm Vulcan seen as very short range and the longer range M48 Chaparral missile systems.

Part of the motivation behind were reports of two new systems that entered service in the early 1980s, one after the others: The Mi-24 Hind which was fearsome in itself but was now upgraded as a "tank killer", fitted with the longer range AT-6 SPIRAL ATGM plus a twin barrelled 23mm cannon firing new APCRE rounds. The second was the more recent adoption of the brand new and dedicated (first of the kind in USSR) Mi-28 Havoc combat helicopter. The latter was a two-seat tank killer, and it just started deployment with far better sights and sensors as well as aneven greater armament compared to the "Hind". It became obvious that the M163 and M48 systems were out-classed.

The U.S. Army Air Defense Artillery (ADA) branch eventually found later a solution to replace the M163 Vulcan with the Avenger HMMWVs armed with Stinger SAMs. The Hummer as a common base was a good choice, and faster. But no gun system was studied pas the failure of the M247, which by the way had only a 4 km range, four times that of a the Vulcan and was more capable, but its guidance never properly worked. In the end, the Stinger Hummer proved a very small, mobile and cheaper solution. Stingers being MANPADS were also deployed in most infantry units and armoured units support teams. It offered far more flexibility than dedicated vehicles. It could be argued aslo that the M2 Bradley could also offer that kind of gun defence in the late 1980s as well, as the Bushmaster was a capable and potentially lethal gun against any Soviet helicopters.

Design

Main Vehicle

M163, Official photo for the technical booklet

The original chassis of the M113 was modified with a suspension lock to provide a stable firing platform. The flanks also received sponsons to add buoyancy due to the weight of the main gun, however the new vehicle was barely buoyant. Later a more dedicated platform provided by FMC was chosen, the M741 A1. This new chassis from the M163 A1 onwards was based on the M577 A1 command vehicle and related to the M548 cargo carrier and M667 Lance carrier as well as the M730 Chaparral.

The vehicle retains its essential architecture with the engine in transverse position forward with the transmission to the left and the driver behind in its own hatch. There is also a right side hatch for the commander and the gunner and loaders in the fighting compartments. The latter was deeply modified unlike the M113 to have the turret basket and its single operator, with boxes of spare ammunitons in the remaining space and a radar console manned by the loaded in the initial phase of fire preparation.

Protection wise, it is inherited from the M113 with a Rolled 5083/5086 H32 aluminum armor protecting the crew from small arms fire and shell splinters. The turret is however open and partly exposed so the vehicle is not NBC protected. There are no smoke grenade dischargers either for concealment. The hull protects from up to 13 mm machine gun fire but not more. There are also automatic Halon fire extinguisher systems in rear compartment and engine compartments. The front is 1.5 inches (38 mm) and sloped, protecting even against 20 mm autocannons and 14.5mm AP Soviet DShK/SVT rounds. But the flanks are straight and 1.75 inches (44.5 mm) thick only. The rear (electric ramp) is also 1.5 inches (38 mm) and the floor does not protects from mines, being flat and 1.125 inches (2.858 mm) thick.

Powerplant and performances

The M163 is significantly heavier than the M113 at 24,700lbs or 12 tonnes, while keeping its dimensions, less the superior height at 115 inches or 2,92 meters. It is also beamier than the base vehicle with its floatation pods, at 112.4 inches or 2,855 meters. The engine is a General Motors 6V53 V6 cylinder, 2 cycle. Gross horsepower is 212 hp at 2,800rpm, Gross torque is 492 ft-lb at 1,300rpm. Fuel capacity goes with a twin tank with 95 gallons (360L) diesel.

This engine is coupled with an Allison TX-100, 3 ranges forward, 1 reverse gearbox, with DS200 controlled differential from steering levers. The Brakes uses Differential band. The vehicle has front drive sprockets (10-tooth) and rear idlers, five main axles (tread) with stamped roadhweels suspended by Torsion bar, 5 individually sprung dual/track and Flat track systems with dual adjustable at rear of track. There are hydraulic shock absorbers on the first and last road wheels/track. The tracks are standard M113 T130E1 with center guide, single pin, in soft steel with detachable rubber pads, 63 shoes left, 64 right, 15 inches (38 cm) wide. The ground contact band is 105 inches or 2,67 meters.

Main Gun

The GM rotary cannon during Operation Desert Storm in 1992

The 20mm Cannon M168 is fitted on a the M157 mount. A six-barreled; rotary Gatling type ordnance it is normally fed by a total of 2,100 rounds, 1,031 ready rounds in four-belt feed (external). Turret traverse is 360°, electric at a rate of 75°/sec, +80° max elevation down to -5° depression, and a traverse of 60°/sec. This gun has a selective rate of fire bertween 1.000 and 3.000 rpm, all 20x102mm ammunition HE-Frag with tracers. Max range is 1.2 km, ground support range 3 km, slant range 4.5 km. The A1 PIVADS upgrade combined with APDS ammunition increased this range to 2.6 km.


Turret assembly, official doc.


Barrel details, official doc.

The original VADS system uses manual guidance using optics and the PIVADS upgrade of 1982 adds a 5 km range radar, but also a lead computing sight with microprocessor plus an improved electric drive system with full stabilization. Still, the vehicle has to stop to fire. This remains however a clear weather only system and pretty useless against jets. It is best use is against helicopters and piston-powered airplanes, especially at lower altitudes.

Other equipments includes a Computing sight M61, a telescope M134, a night vision sight AN/TVS-2B for the gunner, and infrared periscope M19 for driver, a night vision sight AN/TVS-2B for gunner and to assit the gun laying and aimling, a Rangefinder with the short Ranging radar AN/VPS-2.

Variants

Israeli Machbet

M163

Basic model tested in 1966, in service in 1968 deployed in Vietnam until 1973.

• AVADS:

  Automatic track VADS prototype by GM for the Gun Air Defense Effectiveness Study in 1974. Lead-generating fire control computer plus helmet mounted sight.

M163 A1

Upgrades for reliability, availability, maintainability (RAM), former M163E1 standardized in September 1976. 1982 models based on the M741A1 carrier and former ones retrofitted to the M741A1 standard until 1985.

M163 A2

PIVADS (1984) accuracy and workload upgrade was Lockheed Electronics: Digital microprocessor, new director sight, night sight, low backlash azimuth drive system based on the M741A1 platform.

M167

Towed variant towed by the M561 Gama Goat and after 1989, by the Humvee.

Machbet

IDF variant with a 4-tube FIM-92 Stinger pod, Elbit tracking system and datalink with local radars.

---

M163/A1*/A2** VADS specifications 1968
Dimensions	191.5 x 112.4 x 115 in (4.86 x 2.85 x 2.9 m)
Total weight	24,700 lb (11,200 kg)
Total weight*	27,140 lb (12,310 kg)
Total weight**	27,542 lb (12,493 kg)
Crew	4 (commander, gunner, loader, driver)
Propulsion	GM 6V53, 6-cyl. 2-stroke diesel 212 hp (158 kW)
Suspension	Torsion bar, 5 road wheels
Speed (road)	40 mph (64 km/h)
Range	275 mi (443 km); 300 mi (480 km)*
Elevation	+80° / -5°
Armament	M168 GD 20 mm Rotary cannon, 2,000/2,230* rounds
Armor	RHA 5083/5086 H32 alu. 29-45 mm (1.14-1.77 in)
Total production

Combat Operations

M163 Vulcan 5/2nd Artillery, Vietnam 1971

(To come in a future update)

Operators

Chile: 44 from US depots in 1999-2000.
Ecuador: 44 transferred and active as of 2024.
Israel. Tactical Anti-Air units, upgraded as 'hovet'(stingers) retired 2006.
Jordan: 100 purchased from the US, date unknown. Active.
Morocco: 110 purchased from US, 60 still in service.
Portugal: 36 ex-US ordered in 1986, supply parts for the M113A2.
Saudi Arabia: 60 received from the USA in 1978-79. Active
Sudan: 8 donated in 1981, no longer serviceable.
Thailand: 24 in service in 2024.
USA: Removed from service in 1994, most resold.
Yemen: 34 from the US in 1979, no longer serviceable.

Illustrations

VADS of the 2nd Air Defence Artillery Regiment 5th Batallion, Vietnam December 1969


M163 of the 67th Air Defence Artillery Regiment,2nd Batallion Totendorf, Germany 1974.


M163 of the Chilean Air Force at Puntas Arenas, 1980


M163 of the IDF


M163A1 of the 24th Infantry Division, 1st Brigade, 5th Air Defence Artillerie Fort Irwin 1988


M163A1 in MERDC camo, Germany 1980


M163 VADS of the Moroccan FAR, Polisario front 1990s


M163 of the 1st Cavalry Division Museum at Fort Hood, Texas 2005.

Photos

M163A2 VADS Op. Desert Storm

M163A1 Vulcan at the National Training Center in Fort Irwin, California 1988

M163A2 of the 1st Bat. 3rd Arm. Cav. Rgt., Desert Shield 1992

1st Vulcan Combat Team in Vietnam 1969, Barney Bigwood collection (pinterest)

Fort Hood, TX vehicle

Same

ex-IDF at Batey al Hosef Museum

More

Books

Cagle, Mary T. (19 December 1968). History of the Mauler Weapon System (PDF). United States Army Missile Command.
Cagle, Mary T. (31 May 1977). History of the Chaparral/FAAR Air Defense System (PDF).
Cullen, Tony; Foss, Christopher F, eds. (1992). Jane's Land-Based Air Defence 1992-93 (5th ed.).
Department of the Army (1974). Proceedings of the Thirteenth Annual U.S. Army Operations Research Symposium 1974
Department of the Army (May 1976). Operator's Manual For Gun, Air Defense Artillery, Self-Propelled 20-mm, M163
Department of the Army (December 1996). ARMY AMMUNITION DATA SHEETS SMALL CALIBER AMMUNITION Hunnicutt, R.P. Bradley: A History of American Fighting and Support Vehicles. Presidio Press, 1999
TM 9-2350-300-10 C4 Operation and Maintenance Manual (Crew) for Gun, Air Defense Artillery, Self-Propelled, 20-mm, M163A1 (2350-01-017-2113). Washington, DC
TM 9-2350-300-10 Operator's Manual for Gun, Antiaircraft Artillery, Self-Propelled: 20-mm, XM163 (2350-999-4392). Washington, DC 1971
Crismon, Fred W. U.S. Military Tracked Vehicles. Osceola, WI: Motorbooks International, 1992.
Hogg, Ian V. The Greenhill Armoured Fighting Vehicles Data Book. London: Greenhill Books, 2000.

Links

globalsecurity.org
afvdb.50megs.com
weaponsystems.net
militaryfactory.com
Video on the updated Gun
en.topwar.ru
Federation of American Scientists. "M163 Vulcan Air Defense System."

Video

Model Kit:

On scalemates, all kits, 1/35 to 1:72