AIM-47 Falcon

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.

The project first started as part of the Air Force's LRI-X Mach 3 interceptor requirement. In 1957 Hughes won the weapons systems contract, consisting 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 conventional warheads or a 0.25 kiloton version of the W42 nuclear warhead. When the F-108 was announced as the winner of the LRI-X contest in April 1958, the same day the Hughes entries were renamed GAR-9 and AN/ASG-18. When the F-108 was cancelled soon after in September 1959, the Air Force decided to continue development of both missile systems.Sean O'Connor, [http://www.designation-systems.net/dusrm/m-47.html Hughes GAR-9/AIM-47 Falcon] , Directory of U.S. Military Rockets and Missiles, 2004]

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 rocket. Since this would be beyond the range of effective semi-active homing, a new active-radar terminal seeker was added to the missile. This seeker was a powerful system of its own, with no effective maximum range and also able to lock onto a 100 square-foot target at 63 nm (116 km). Even the seeker was to have changed at one point, adding a passive infrared seeker to improve terminal performance. However that would have required the missile to grow by 180 lbs, and in diameter by two inches, making it too large for the F-108's weapon bay. The W-42 nuclear version was dropped in 1958 in favor of a 100 pound high-explosive design.

Problems with the motor during development led to the brief consideration of using a storable liquid-fuel design, but was replaced instead by the Lockheed XSR13-LP-1 solid rocket. This lowered the top speed from Mach 6 to Mach 4. In this form the GAR-9 started ground firings in August 1961. For air-launch testing at supersonic speeds they had originally suggested using the Republic XF-103, but this project had been cancelled before reaching the prototype stage. Instead, B-58 Hustler s/n 55-665 was modified to house the AN/ASG-18 radar in a large protruding radome that gave it the nickname "Snoopy", and in-flight launches started in May 1962.

In 1960 Lockheed started development of the Lockheed YF-12 interceptor, as a lower-cost replacement for the F-108. The GAR-9/ASG-18 were moved to this project. The F-12 would have featured four flip-open internal weapons bays on the chines behind the cockpit, although one of these was filled with electronics. However, a redesign for the F-12B meant these bays were too small for the GAR-9, so the GAR-9B was developed with flip-out fins to reduce its diameter.

Test firings of the GAR-9A from the prototype F-12As resulted in six kills from seven launches, the lone miss due to a missile power failure (there were several non-guiding test launches as well). The missile was re-named AIM-47 in the fall of 1962 as part of the tri-service common naming exercise. The last launch was from a YF-12 was flying at Mach 3.2 and an altitude of 74,400 feet (22,677 m) at a QB-47 target drone 500 feet (152 m) off the ground. [B. Rich, "Skunk Works" (Boston: Little, Brown, and Co., 1994), p. 236]

Like the F-108 before it, the F-12 project was itself cancelled in 1966. The only other projects to have expressed an interest in the design were the also-cancelled XB-70 Valkyrie, which could have carried the AIM-47 for self-defense. Development continued anyway, and in 1966 the basic airframe was adapted with the seeker from the AGM-45 Shrike and the 250 lb warhead from the Mk. 81 bomb to create the high-speed AGM-76 anti-radar missile, although this did not appear to see service.Andreas Parsch, [http://www.designation-systems.net/dusrm/m-76.html Hughes AGM-76 Falcon] , Directory of U.S. Military Rockets and Missiles, 2004]

The Navy also had a requirement for a long-range missile system for their F6D Missileer, consisting of the Bendix AAM-N-10 Eagle missile and Westinghouse AN/APQ-81 radar. When the F6D was cancelled in December 1960 the weapons programs continued briefly. Attention later turned to the Hughes systems, which were much further along in development and offered similar performance. One advantage of the Eagle was that the radar sent it mid-course corrections, which allowed the fire control system to "loft" the missile up over the target into thinner air where it had better range. This, and other technologies, were transferred from the Eagle to the AIM-47, producing the new AIM-54 Phoenix (originally the AAM-N-11), intended for the General Dynamics F-111B. This project was also canceled in 1967, and the system finally found a home on the F-14 Tomcat, entering service in the early 1970s.

Hughes had built some 80 pre-production missiles.

See also

* Missile designation

References

External links

* [http://www.youtube.com/watch?v=WYKbPPRFE6o AIM-47 Falcon missile launch]