In 1963, twelve Navy F-4Bs were modified as F-4Gs. This was a Navy
designation, not to be confused with the USAF F-4G of twelve years
later, which was a *Wild Weasel* aircraft.
The Navy F-4G was a version of the F-4B modified for the evaluation of
the feasibility of a SAGE-like ground control system for fleet air defense. The Navy
hoped to be able to connect its fighters, ships, and AEW aircraft by a
two-way datalink network so that fighters could be controlled through
a communication link that coupled their autopilots to a ship or
aircraft-based controller. The intent was to make it possible to
carry out automatically-controlled interceptions without the need for
voice commands from ground controllers. The same system would,
incidentally, make night/all-weather automatic carrier landings
possible.
In support of this program, a single F-4B (BuNo 148254) was fitted
with an AN/ASW-13 two-way datalink communication system and approach
power compensator which, coupled with the shipboard AN/SPN-10 radar
and AN/USC-1 datalink allowed hands-off carrier landings to be
accomplished. Tests proceed well enough so that the ASW-13 was
replaced with an AN/ASW-21, which in addition to the datalink capability
also allowed weapons, oxygen, and fuel status to be relayed to the
controller. A radar reflector had to be attached to the nose in order
to produce a larger radar target that would
permit the AN/SPN-10 ship-borne radar to track the F-4 during
automatic landings. Initially, the radar reflector was bolted onto
the nose gear ddor, but in production versions the reflector retracted
into a cavity underneath the nose immediately ahead of the
landing gear. Other changes included the reconfiguration of the
number 1 fuel tank, which had to lose 600 pounds of fuel in order to
make room for the datalink equipment. The cockpit configuration had
to be revised slightly to incorporate the datalink system--new control boxes and
indicators were installed in the rear cockpit, and a panel with status lights
and an acknowledge button was installed in the front cockpit to inform the
controller that information had been received. A distance-to-touchdown indicator
was also installed on the instrument panel. The autopilot system was modified
to permit inputs from the datalink system to drive the flight controls. An
automatic approach power compensator system system was installed to automatically
control the engine throttles while the aircraft was in the landing approach phase.
Twelve more F-4Bs were converted to this standard on the production
line. Their serial numbers were BuNos 150481, 150484, 150487, 150489,
150492, 150625, 150629, 150633, 150636, 150639, 150642 and 150645. The first
of these (150481) flew on March 20, 1963. These planes differed from
148254 in having a retractable rather than fixed radar reflector
immediately ahead of the nose-wheel bay. In early 1963, two of these
planes (150489) and 150625) were sent to the NATC at Patuxent for testing of
the automatic carrier landing system, and in the summer of 1963
the remainder were given to VF-96 at NAS Miramar for testing.
In January-March 1964, the 10 VF-96 planes were transferred to VF-213.
On March 31, 1964, the NATC aircraft were redesignated F-4G, and the
VF-213 aircraft followed suit on April 6. The F-4Gs of VF-213 were
operated aboard the USS *Kitty Hawk* in the Gulf of Tonkin from
November 1965 until June of 1966. One (150645) was lost to North Vietnamese
AAA, but the others were stripped of their AN/ASW-21 datalink gear and brought
back to F-4B standards and were dispersed throughout
the Navy and Marine Corps. Seven survived long enough to be converted to
F-4N configuration.
The automatic landing and remote-controlled intercept capabilities
tested by the F-4G were later incorporated into later production
blocks of the F-4B by addition of the AN/ASW-125, which, however,
lacked the two-way feature of the AN/ASW-21.
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