Another somewhat less well-known role for the Hustler was that of a testbed for the weapons and fire control system of the Lockheed YF-12A Mach 3 interceptor.
The missile and fire control system for the proposed YF-12A was to be the Hughes Aircraft Company AN/ASG-18 fire control system and associated GAR-9 (AIM-47A) air-to-air missile that had originally been developed for the abortive F-108 Rapier program. Since the weapons system was going to be ready for test before the YF-12A aircraft was, the USAF decided that they could speed up the program by fitting the weapons system into a special testbed aircraft that would do some of the earlier evaluation of the system until the YF-12A could be ready.
On October 17, 1958, Convair received a contract from Hughes and the USAF to manufacture two special pods for GAR-9 missile launch tests and to modify one B-58 for AN/ASG-18 testbed work. B-58A serial number 55-665 was selected for the modifications.
In order to fit the rather large AN/ASG-18 fire control system into the B-58A, nearly seven feet had to be added to the overall length of the aircraft. The AN/ASG-18 radar system had one of the largest articulated antennae ever mounted on an aircraft up to that time. The AN/ASG-18 system also had a significant infrared capability, and an infrared sensor dome was mounted on each side of the forward fuselage ahead of the cockpit. Internal changes had to be made in the second crew station and elsewhere to accommodate the associated instrumentation and control equipment.
A special ventral pod had to be developed to carry and launch the GAR-9 missile. The new type of pod carried no fuel, but had a large internal bay for a single GAR-9 missile with associated cooling system, telemetry equipment, and tracking flares. Two pods were built.
The flight testing of the radar began in early 1960, but the first GAR-9 launch did not take place until May 25, 1962. By late 1963, the YF-12A flight test program was sufficiently well advanced that it was concluded that it was now possible for future GAR-9 missile launches to take place from the YF-12A itself. The last B-58 GAR-9 launches took place in February of 1964.
After the completion of the ASG-18/GAR-9 test program, the special
modifications were removed from 55-0665. However the long nose
was retained. 55-0665 was eventually placed out in the open
on the photo test range at Edwards AFB. Is it still out there?