Cancellation of Mauler left the US Army with no modern anti-aircraft weapon, and they rushed development of the much simpler MIM-72 Chaparral and M163 Tracked Vulcan to fill this niche.
[3] Although the Vigilante was, like the Duster, optically aimed and guided, its high (3,000 rounds per minute) firing rate gave it much better performance against high-speed aircraft.
As the Vigilante program continued, the Army decided that any gun-based system was hopeless as speeds increased and engagement times dropped.
The Army decided to cancel Vigilante and keep the Duster in service until a much more capable phase III all-missile system arrived to replace it.
[3] Phase III was intended to produce an ultimate answer to air defense of front line Army troops.
[3] The Army decided to pursue the "best weapon system that could be developed to meet requirements of the forward area on a liberal time scale" to be available in the 1965 period.
[3] Under the "Forward Area Air Defense" project, the Army began collecting theoretical data on the requirements for a missile-based system in 1959.
This system had the advantage that the radar signal continued to grow in strength as the missile approached the target, making it increasingly easy to track.
More importantly, the reflected signal was a cone shape centered on the target, so guidance became increasingly accurate as the missile approached.
In particular, in the case of beam-riding the signal is shaped like a cone centered on the broadcaster, which means it becomes increasingly inaccurate as the missile flies towards the target.
The British Army's intended role was essentially identical to the US's, but the Navy was looking for a solution to the problem of air attack against their capital ships both by high-speed aircraft as well as early (non-skimming) anti-shipping missiles.
Additionally, its fast-acting semi-automatic fire control was highly desired for a weapon that was expected to counter targets with engagement times under a minute.
Both test series demonstrated a variety of problems, including failures of the rocket casings, and excessive drag and wing flutter.
[15] The Performance Evaluation & Review Technique (PERT) originally devised for the Polaris system in 1958 was introduced into the Mauler effort in 1962–63.
[21] Inadequate funding, a lack of guidance from higher headquarters, changes in requirements, and unsolved technical problems led to a loss of confidence.
Their analysis suggested that the conversion would be simple, but the missile's long lock-on time and optical guidance would make it ineffective in close combat.
Known as the "Interim Field Army Air Defense Study", it called for a multi-layer system consisting of an adapted Sidewinder as a missile component known as the MIM-72 Chaparral, a short-range gun component using the M61 Vulcan known as the M163 VADS, and the separate AN/MPQ-49 Forward Area Alerting Radar that would support both by sending digital information to displays in those platforms.
This suggested the use of a fast-acting gun system, albeit one with much longer range than the Vulcan's 1,200 m. Out of these studies came the "Division Air Defense" concept that was eventually filled by the M247 Sergeant York.
However, the ending of the Cold War led the Army to cancel their ADATS purchase, leaving the Chaparral/Vulcan combination in service even longer.
It was believed that Mauler would greatly improve the capabilities of smaller ships, allowing them to take on some of the roles that would normally require a much larger platform, like a full destroyer.
Although the Sparrow was a capable missile, it was intended for launch from high-speed aircraft and thus had relatively low acceleration, trading this for longer cruising time and range.
The missiles were held in a large eight-cell rotating launcher that was slaved to the illuminator in order to allow the seeker to see the reflected signal.
This was again upgraded to allow the phased-array radars of modern ships to guide the Sparrow directly, removing the need for the relatively large illuminators.
The evolution continued with the latest models, which can be vertically launched from four-cell containers, greatly expanding the number that can be carried on most ships.
The entire system was mounted at the back of the XM546 "Tracked Fire Unit" on a rotating platform that allowed the missiles to be pointed toward the target.