Эволюция американских зенитных систем: от Duster до Chaparral и Mauler.

The first proposed replacement for the Duster was the Sperry Vigilante, which referred to the six barreled 37 mm Gatling gun proposed as the basis for a new SPAAG. Although the gun was extremely powerful, at some point in the late 1950s the Army decided that all gun based systems were out of date. The next proposed replacement for the Duster was the ambitious MIM 46 Mauler missile system. Mauler mounted a nine missile magazine on top of an adapted M113 Armored Personnel Carrier chassis, along with detection and tracking radars. Mauler featured a completely automatic fire control system, with the operators simply selecting targets and pressing "OK". It would be able to respond to low flying high speed targets at any angle out to a range of about five miles. However, Mauler proved to be beyond the state of the art and ran into intractable problems during development. Realizing it was not going to enter service any time soon, it was downgraded to a technology demonstration program in 1963, and eventually canceled outright in 1965. Still lacking an effective anti aircraft system, the Army started development of two stop gap systems that were meant to operate in concert as the "Chaparral Vulcan Air Defense System". The M163 VADS combined the M61 Vulcan cannon, the M113 chassis, and an all optical fire control system with a simple lead computing gunsight. Suitable for "snap shots" against nearby targets, the VADS system was equipped only with a small ranging radar for the gunsight, its firing range being too small to justify a larger tracking radar. VADS was intended to operate in concert with the MIM 72 Chaparral missile system, which combined the AIM 9 Sidewinder missile with a more heavily modified version of the M113 chassis. The Chaparral's AIM 9D missiles were capable of tail chase launches only, but offered ranges up to 5 mile (8 km). Also using an all optical firing system, the Chaparral nevertheless required the operator to "settle" the missiles on the target for a period of time to allow them to lock on, limiting its ability to deal with quickly moving targets. Both vehicles were optionally supported by the AN/MPQ 49 Forward Area Alerting Radar (FAAR), but this system was towed by the Gama Goat and could not be used near the front lines. The Soviets initially lagged behind the U. S., but the introduction of the 9K114 Shturm missile on the Mil Mi 24 (called the "Hind" by NATO) in the 1970s offered the USSR a level of parity. Unlike fixed wing aircraft, attack helicopters had the ability to loiter near the front behind cover and pick their targets. They would then "pop up", launch a missile, and return to cover as soon as the missile hit its target. Using fast reacting wire guided or radio command missiles meant the total engagement time was kept to a minimum, as there was little or no "lock on" time required; the operator simply fired as soon as they were clear of the terrain, and then adjusted the missile's flight path onto the target while it flew. Against these aircraft, the Vulcan/Chaparral combination was effectively useless. The Vulcan could react quickly enough to the fleeting targets, but its 20 mm gun had an effective range of only about , far shorter than the range of the 9K114. While the Chaparral had enough range to engage the "Hind", its lengthy lock on period meant the Hind would have hit its target and hidden behind terrain again before the Sidewinder would reach it. Additionally, the older Sidewinder missiles used on the Chaparral homed in on exhaust, and had limited capability against helicopters faced head on. The limited effectiveness of the Vulcan/Chaparral was not the only problem the US Army was facing in the late 1970s. At the time they were also in the process of introducing the new M1 Abrams and M2 Bradley vehicles, which had dramatically improved cross country performance. The M113 based Vulcan and Chaparral could not keep up with them on the advance, which would leave the new vehicles open to attack in a fast moving front. Finally, the Soviets were widely introducing the ZSU 23 4 "Shilka" SPAAG, which was cause for some concern after it appeared in the Middle East. Israeli pilots attempting to avoid fire from Syrian SA 6 batteries would fly low, directly into the Shilka's envelope. Several aircraft were lost or damaged. The Shilka proved that a modern SPAAG was effective against modern aircraft.

For all of these reasons, the Army developed the "Advanced Radar directed Gun Air Defense System" (ARGADS) requirement for a new weapon system combining the reaction speed of the Vulcan with the range of the Chaparral, and placing them on a chassis that could keep up with the new tanks in combat. They also worked in the earlier FLIR/laser requirement. The system was later renamed "Division Air Defense" (DIVAD). At the time, most U. S. military policy was based on the US Air Force quickly gaining air superiority and holding it throughout a conflict. In keeping with this, the Army had previously placed relatively low priority on anti aircraft weapons. This gave them time to mature through testing and shakedowns. In the case of DIVADs the threat was considered so serious and rapidly developing that the Army decided to skip the traditional development period and try to go straight into production by using a number of "off the shelf" parts. Colonel Russell Parker testified before the Senate Armed Services Committee in March 1977 that "We expect this somewhat unorthodox approach to permit a much reduced development time, thus resulting in an earliest fielding date, albeit with higher but acceptable risks the manufacturer will be required by the fixed price warranty provisions, to correct deficiencies."

Several companies responded to the DIVADs contest. Sperry Rand entered a system based on their older Vigilante gun, modified to fire the 35 mm round from the Oerlikon KDA series, widely used in NATO in the anti aircraft role. The gun could be fired at 3,000 rounds per minute for anti aircraft use, or 180 rounds per minute for use against ground targets, fed from a 1,464 round magazine. The aluminium turret was topped by two radars and an IFF system, all from Sperry. General Electric entered a version with a small turret mounting their 30 mm GAU 8 Avenger cannon from the A 10 Thunderbolt II. It included a single search/track radar adapted from the earlier FAAR, although they later suggested an improved system. Raytheon proposed using the turret from the Dutch version of the German Flakpanzer Gepard. Most of the turret remained the same as the original Gepard, including the twin 35 mm Oerlikon KDA cannons, but used Hollandse Signaalapparaten radars and an Oerlikon Contraves fire control computer. Raytheon demonstrated that the turret, although designed for the Leopard 1, could be mounted on the M48 with some adaptation. General Dynamics' entry also mounted twin Oerlikon KDA cannons, but mounted them side by side in a new aluminum turret, as opposed to either side of the turret as in the Gepard. They could be fired in either the automatic or semiautomatic mode, and their combined rate of fire was 1,100 rounds per minute from a 600 round magazine. The radar and fire control systems were derived from their Phalanx CIWS system, with the tracking radar mounted on the front of the turret, beside the guns, and the search radar on top. The turret also included independently stabilized optical sights and a laser range finder for manual engagements. However, the Bofors 40 mm L/70 cannon also had worldwide popularity and had become NATO standard back in the mid 1950s. In addition, FACC had developed a proximity sensing round for the 40 mm, which increased probability of a kill, and the shell carried either a greater explosive charge or higher deadweight mass than the smaller anti aircraft platforms. These factors would be important in the primary scenario for which the DIVAD was to be deployed, that being the large theater land operations vs the Warsaw Pact.

On 13 January 1978, General Dynamics and Ford were given development contracts for one prototype each, the XM246 and XM247 respectively, to be delivered to Fort Bliss in June 1980. On schedule, both companies delivered their prototypes to the North McGregor Test Facility and head to head testing began. The shoot off was delayed for two months "because the prototypes which arrived at Fort Bliss test range were too technically immature." In the DT/OT II test series they shot down two F 86 Sabre fighters, five UH 1 Huey helicopters and twenty one smaller drones. After the 29 month Phase One trial, Ford's entry was selected as the winner of the DIVADs contest on 7 May 1981, and given a fixed price $6.97 billion development and initial production contract for deliveries at various rates. The decision was controversial, as the General Dynamics entry had "outscored" the Ford design consistently in testing, nineteen "kills" to nine by most accounts. The RAM D (reliability, availability, maintainability and durability) tests ran from November 1981 to February 1982, demonstrating a wide range of operation concerns. One of the early models was reported to have locked onto a latrine fan, mistaking its return for a moving target of low priority. Reporting on the incident in another article on the vehicle's woes, Washington Monthly reported that "Michael Duffy, a reporter for the industry publication Defense Week, who broke this aspect of the story, received a conference call in which Ford officials asked him to describe the target as a 'building fan' or 'exhaust fan' instead." Nevertheless, the program's manager within the Army was cautiously positive. Major General Maloney said, "The DIVAD battery eight systems plus one spare activated 1 November 1984, at Fort Bliss to prepare for tests, has been demonstrating 90% reliability for full systems capability. The systems have been able to operate in a degraded manner a further 2% of the time and have had an 8% inoperable rate." He later stated that the "gun still had problems with software and electronic countermeasures, but my sensing was that it was certainly no worse than many weapon systems at this period in their gestation". The tests were carried out late in 1984. The results were abysmal. When the gun proved unable to hit drones moving even in a straight line, the tests were relaxed to hovering targets. The radar proved unable to lock even to this target, as the return was too small. The testers then started adding radar reflectors to the drone to address this "problem", eventually having to add four. Easterbrook, still covering the ongoing debacle, described this as being similar to demonstrating the abilities of a bloodhound by having it find a man standing alone in the middle of an empty parking lot, covered with steaks. The system now tracked the drone, and after firing a lengthy burst of shells the drone was knocked off target. As it flew out of control, the range safety officer had it destroyed by remote control. This was interpreted by the press as an attempt to "fake" the results, describing it as "sophomoric deceits". From that point on, every test success was written off as faked. The OT&E concluded that the gun could perform the mission as originally specified, but the tests also showed that the system had considerable reliability problems, many as the result of trying to adapt a radar system developed for aircraft to the ground role. Most of the production Sergeants York ended up as targets on air force bombing ranges. However, one is on display at the Sgt. Alvin C. York State Historic Park in Pall Mall, TN where its namesake hailed from, one is in the Wahner E. Brooks Historical Exhibit at the U. S. Army Yuma Proving Grounds, AZ, another is located at the AAF Museum in Danville, VA, one at the Fort Snelling Military Museum in Minneapolis, MN (now closed), and one located at the Arkansas National Guard Museum at Camp Robinson, North Little Rock, Arkansas.

The M247 Sergeant York was referenced in the movie "Pentagon Wars", where it, along with other Army projects, such as the Paveway Laser Guided Bomb, is severely criticised for its lack of success in testing, despite the long and expensive efforts put forth.

Philip Trewhitt, "Armoured Fighting Vehicles", Prospero Books, 1999 (second edition? ).