The Hughes AIM-47 Falcon, originally GAR-9, was a very long-range high-performance air-to-air missile that shared the basic design of the earlier AIM-4 Falcon. It was developed in 1958 along with the new Hughes AN/ASG-18 radar fire-control system intended to arm the Mach 3 XF-108 Rapier interceptor aircraft and, after that jet's cancellation, the YF-12A(whose production was itself cancelled after only 3 vehicles). It was never used operationally, but was a direct predecessor of the AIM-54 Phoenix used on the Grumman F-14 Tomcat. Development Development for XF-108 In the early 1950s, the United States Air Force developed requirements for a high speed, high performance interceptor aircraft, originally called the LRI-X. In 1957, Hughes won the contract to supply the weapons system for this aircraft. This system consisted of the GAR-X missile and the YX-1 radar and fire control system. The original missile design had a range of 15 to 25 miles (25 to 40 km), and could be equipped with a conventional warhead or a 0.25 kiloton version of the W42 nuclear warhead. When the North American XF-108 Rapier was announced as the winner of the LRI-X contest in April 1958, the Hughes entries were redesignated GAR-9 and AN/ASG-18 on the same day. The F-108 was cancelled in September 1959, but the Air Force decided to continue development of the missile system with both warheads. During its development, the capabilities of the new missile grew tremendously. Growing much larger, the missile's range was extended to 100 miles (160 km), using the Aerojet-General XM59 solid-fuel motor. Since this would be beyond the range of effective semi-active radar homing, a new active-radar terminal seeker was added to the missile. This seeker was a powerful system of its own, with the resolution to be able to lock onto a target at 63 nm (116 km). Using an active seeker eliminated the inherent long-range inaccuracy of semi-active homing, allowing the missile to be launched at any range where it could see the target. Some consideration was given to the addition of a passive infrared homing seeker to improve terminal performance but that would have required the missile to grow by and two inches in diameter, making it too large for the F-108's weapon bay. The W42 nuclear version was dropped in 1958 in favor of a high-explosive design. Problems with the motor during development led to the brief consideration of using a storable liquid-fuel rocket