Military

M163 VADS Vulcan Air Defense System
M163A2 PIVADS Product Improvement Vulcan Air Defense System

The M163 is a self propelled variant of the General Dynamics 20mm M61 rotary cannon mounted in most US aircraft since the 1960s used for air defense. Long the standard mobile light anti-aircraft gun of the US Army, the Vulcan's only limitation was that it could not cannot be used for night time operation. A series of modifications to improve the reliability, availability, and maintainability (RAM) of VADS were developed during the early 1970s by the US Army Armament Command (ARMCOM), the Tank and Automotive Command (TACOM), and system contractors. Because of the large number modifications, the total impact to VADS was considered a major change and the modified systems had an "Al" model configuration. In March 1975, AMC received DA direction to accelerate the VADS product improvement program. During June 1975, ARMCOM was granted special procurement authority (sole source), and authority to field with draft technical manuals (TMs) in order to accomplish an accelerated application. The application of the modification kits to the systems in the field was accomplished by depot level contractor teams as part of an accelerated program.

The goal of the radar reliability product improvement was to increase the mean-time-between-failure (MTBF) from 30 hours to 100 hours. During the Product Improvement Verification Test (PIVT), a MTBF of 122 hours was demonstrated. To achieve the 122 hours MTBF, approximately 200 components were removed and replaced. Modifications were made to internal RF cables, electrolytic capacitors, operational amplifiers, RF filters, blower motor inverter, klystron power supply circuit, enclosure gaskets, radiate lens, and parts of the power supply.

A product-improved VULCAN air defense system had been considered in Army studies as a possible alternative to the Division Air Defense Gun for the heavy divisions. Although the improvement effort has not yet been funded by the Army, modification kits had been developed by the manufacturers at their own expense and limited demonstrations have been performed. The proposed product improvements were intended to extend the effective range and improve reliability and availability characteristics of the towed VULCAN. The Congress added funds to the fiscal year 1981 Department of Defense budget as a near term readiness initiative to upgrade the air defense capabilities of the airborne and air assault divisions of RDF. The proposed product improvements (1) would extend the VULCAN's range with new ammunition, (2) enhance operability and tracking accuracy, and (3) reduce reaction time.

Opinions varied within the Department of Defense concerning the need for and the effectiveness of the improved VULCAN program. The Principal Deputy Undersecretary of Defense for Research and Engineering stated that the improved VULCAN will be effective against the less intense air attack that Defense expects in non-European theaters. The US Army Air Defense School favored interim retention of the VULCAN and its improvement program. Army headquarters officials supported the improved WLCAN as long as the Congress provided the funds, saying that the improvement program would make VULCAN a more capable weapon system. The Army's Training and Doctrine Command opposed any improved VULCAN program, stating that even with the improvements it provided less than required increases in range and doubtful increases in effectiveness. The Army's Materiel Development and Readiness Command also believed that the improved VULCAN was not operationally effective even as an interim system and any decision to acquire PIVADS could adversely affect a decision to acquire a new lightweight air defense system.

In 1984, the ground service began to upgrade many of these cannons in the Product Improved Vulcan Air Defense System project that added a digital computer and range-only radar. These modifications increased effectiveness and simplified operations. Another improvement was new ammunition (armor piercing discarding sabot) that increased maximum effective antiaircraft range from 1,600 to 2,600 meters.

Army efforts to replace the Vulcan with a more advanced gun system ended in disaster. Since World War Two, the US Army's ground forces had not been subjected to a serious enemy air threat that would have crippled their ability to operate. Air superiority had been the mainstay of US air defense and has succeeded in lulling US forces into a false sense of security. However, by the 1970s most analyses and intelligence reports tended to state future conflicts in a mid to high intensity arena would possibly see US forces subjected to periods where the enemy would possess air parity or even air superiority over selected portions of the battlefield. The modern battlefield was expected to be a broad non-linear expanse of territory that would see concentration of forces at selected positions to meet the enemy onslaught. Linear regularity as in World War One with its trenches stretching from the Atlantic to Switzerland were an an anomaly not to be repeated.

Knowing there was a deficiency in the forward area air defense with the interim fielding of Vulcan, the Army initiated separate studies of the subject from 1972 to 1976, and all reinforced the basic assumption that a new gun was required. This "study to death syndrome" cost ADA and the Army four years in attempting to acquire the optimal system for the division.

From 1984 many M163 were upgraded under the M163 PIVADS Product Improved Vulcan Air Defence System program. Modification include new linked digital fire-control computer with range-only radar, and adding the new APDS round which increases range to 2,600m. The ill-fated M247 SGT. YORK DIVAD (Division Air Defence gun) was born of the U.S. ARMY'S need for a state-of-the-art mobile Anti-Aircraft gun system to replace the ageing M163 20mm Vulcan A/A gun and M48 Chaparral missile systems.

With the Mi-24 Hind attack helicopters of the Soviet Army being fitted with the longer range AT-6 SPIRAL Anti-tank missiles and twin barrelled 23mm cannon, and with the newer Mi-28 Havoc nearing deployment, it was obvious by the early 1980s that the M163 and M48 systems would be totally out-classed in any future conflict. The U.S. Army Air Defense Artillery (ADA) branch retired its M163 Vulcan tracked and towed 20mm Gatling gun systems, replacing them with Avenger HMMWVs with Stinger SAMs.

By the 1980s the requirement for division-level air defense improvement was undisputed. Fundamental to success on the modern battlefield is the ability to operate without undue interference from enemy air. The US put an extraordinary amount of effort into making that come true -- from attacks on enemy airfields, use of fighters against theirs, missile defenses over the battle area, and close-in defenses of the forces. American armored and mechanized forces are the jewels in the air-land battle crown. The Soviets knew that and would go to extraordinary efforts to stop them -- particularly when the US was executing this battle doctrine successfully. Those armored and mechanized forces must be protected. Close-in protection for them when they are on the move would be a key ingredient in making battle doctrine succeed.

Existing short-range air defense systems were not equal to the Soviet threat including the HAVOC standoff helicopter. The Vulcan gun system with its 1.2 km range, visual pointing system, and exposed gunner was simply inadequate. The Chaparral missile system could not keep up with maneuver forces, nor can it shoot on the move. The Sergeant York had a 4 km range -- almost four times the range of the Vulcan. A gun like the Sergeant York would make fighter bomber attacks on US armored forces far more difficult than existing systems. Conversely the Vulcan gun system was so disadvantaged in that circumstance as to be virtually not effective.