The Hughes AIM-4 Falcon was the first operational guided air-to-air missile of the United States Air Force.

Development

Development of a guided air-to-air missile began in 1946. Hughes Electronics was awarded a contract for a subsonic missile under the project designation MX-798, which soon gave way to the supersonic MX-904 in 1947. The original purpose of the weapon was as a self-defense weapon for bomber aircraft, but after 1950 it was decided that it should arm fighter aircraft instead, particularly in the interception role.

The first test firings took place in 1949 at which time it was designated AAM-A-2 and given the popular name Falcon. A brief vogue for awarding fighter and bomber designations to missiles led it to be redesignated F-98 in 1951. In 1955 the policy changed again, and the missile was again redesignated GAR-1.

The initial GAR-1 and GAR-2 models entered service in 1956. It armed the F-89 Scorpion and F-102 Delta Dagger interceptors.

The GAR-1 had semi-active radar homing, giving a range of about 5 miles (8 km). About 4,000 rounds were produced. It was replaced in production by the GAR-1D (later AIM-4A), with larger control surfaces. About 12,000 of this variant were produced, the major production version of the SARH Falcon.

The GAR-2 (later AIM-4B) was a heat-seeker, generally limited to rear-aspect engagements, but with the advantage of being a 'fire and forget' weapon. As would also be Soviet practice, it was common to fire the weapon in salvos of both types to increase the chances of a hit. The GAR-2 was about 1.5 in (40 mm) longer and 16 lb (7 kg) heavier than its SARH counterpart. Its range was similar. It was replaced in production by the GAR-2A (later AIM-4C), with a more sensitive infrared seeker. A total of about 26,000 of the infrared-homing Falcons were built.

All of the early Falcons had a small 7.6 lb (3.4 kg) warhead, limiting their lethal radius. Also limiting them tactically was the fact that Falcon lacked a proximity fuse: the fusing for the missile was in the leading edges of the wings, requiring a direct hit to detonate.

In 1958 Hughes introduced a slightly enlarged version of the Falcon, initially dubbed Super Falcon, with a more powerful, longer-burning rocket engine, increasing speed and range. It had a larger warhead (28.7 lb / 13 kg) and better guidance systems. The SARH versions were GAR-3 (AIM-4E) and the improved GAR-3A (AIM-4F). The infrared version was the GAR-4A (AIM-4G). About 2,700 SARH missiles and 3,400 IR Super Falcons were produced, replacing most earlier versions of the weapon in service.

The Falcon was redesignated AIM-4 in September 1962.

The final version of the original Falcon was the GAR-2B (later AIM-4D), which entered service in 1963. This was intended as a fighter combat weapon, combining the lighter, smaller airframe of the earlier GAR-1/GAR-2 weapon with the improved IR seeker of the GAR-4A/AIM-4G.

The USAF deployed this weapon in Vietnam on F-4D Phantoms. Its combat performance in that conflict was very poor, a combination of slow seeker cooling (taking as much as 6 to 7 seconds to cool the seeker enough to lock onto a target, an eternity in a dogfight), limited coolant supply (which meant that once cooled, the missile would soon expend its supply of liquid nitrogen, making it useless), tiny warhead, and lack of proximity fusing. Only five kills were scored, and the weapon was extremely unpopular with pilots. It was withdrawn after 1969.

An effort to address the AIM-4D's limitations led to the development in 1970 of the XAIM-4H, which had a laser proximity fuse, new warhead, and better maneuverability. It was cancelled the following year without entering service.

The AIM-4F/AIM-4G Super Falcon remained in USAF and ANG service, primarily with F-102 Delta Dagger and F-106 Delta Dart interceptors, until the final retirement of the 'Six' in 1988.

The AIM-4C was also produced for the Swiss air force (as the HM-58), where it was used on Swiss Mirage IIIS fighters, and the Swedish Flygvapen (as the Rb 28) with Saab Draken and Saab Viggen aircraft.

A bigger, nuclear version of the Falcon was developed as the GAR-11 (later AIM-26 Falcon), while a long-range version was developed for the XF-108 Rapier and Lockheed YF-12 interceptors as the GAR-9 (later AIM-47 Falcon)

Specifications (GAR-1D/ -2B / AIM-4C/D)

• Length : 78 in (1.98 m) / 79.5 in (2.02 m)
• Wingspan: 20 in (508 mm)
• Diameter: 6.4 in (163 mm)
• Weight : 119 lb (54 kg) / 135 lb (61 kg)
• Speed: Mach 3
• Range 6 miles (9.7 km)
• Guidance: semi-active radar homing / rear-aspect infrared
• Warhead: 7.6 lb (3.4 kg) high explosive

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