F-111 in Detail

Part Five - Antennas

by Jim Rotramel

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Experience during the Yom Kipper War in October 1973 led to the development and installation of the AN/ALR-62 Compass Sail antenna. Installation of the Compass Sail mod caused the removal of the AN/ALR-41 system and its small antenna, which had previously been located under the nose. As with most fleet-wide modifications, order of installation was SAC FB-111s first, followed by USAFE F-111E/Fs and finally stateside F-111A/Ds. In this instance, SAC installations began in 1980, with USAFE beginning the following year and so forth. Completion of this program took about a year at each base, so all aircraft had probably received ALR-62s by 1983 or so.

On the F-111D, the Compass Sail antenna was located under the nose, to the right of centerline and next to the KB-18 strike camera (which was installed only a year or two earlier). On the F-111A, F-111C, F-111E, and F-111F the antenna was on the centerline, staggered slightly in front of the KB-18. It was also in this location on the FB-111A/F-111G (which had no KB-18).

The EF-111A had neither the AN/ALR-62 Compass Sail antenna nor KB-18. In addition, the retractable anti-collision beacon was moved from between the speed brake and converted bomb bay to just to the left of the centerline-mounted UHF antenna, which was located farther forward on the nose.

The large TACAN antenna just behind the escape capsule on all variants began to be replaced by a smaller one starting in the spring of 1991. Also, during 1989, some F-111Fs were observed with raked-back lower front UHF antennas. This change was made to some, but not all aircraft.

F-111D antenna positions as of 1981 are shown in these photos. Note that strip lights were not yet installed.

The GPS antenna installation used on an F-111E AMP is shown in these photos. This same installation was also used on Pacer Strike F-111Fs and EF-111A AMP aircraft. Only one F-111E was AMP-modified in time for the 1991 Gulf War.

F-111E AMP antenna positions as of 1995 are shown in the above photo. There was no external difference in antenna positions between the E and F.

An F-111F with the raked-back UHF antenna installed on some aircraft in the late 1980s is shown in the left photo. The right photo shows F-111F Pacer Strike antenna positions as of 1995.

F-111G antenna positions as of 1990 are shown above. Note the additional pitot-probe on the right side that was not found on other variants.

EF-111A antenna positions as of 1993 are shown above. Note how the UHF antenna was shifted forward to the location of the KB-18 on other aircraft.

The left photo shows the normal antenna arrangement on the top of the fuselage with the small IFF antenna in the front and the larger UHF/TACAN antenna behind. The aircraft is an F-111F in about 1982. The right photo shows the secondary antenna arrangement, with the IFF using a UHF/TACAN-sized antenna. This configuration was standard on the EF-111 and frequently used by F-111As in Vietnam and stateside F-111s. It was seen less frequently on European-based F-111E/Fs.

On the left is a close up of an anti-collision beacon, this one mounted in the non-standard EF-111A position slightly ahead and left of the lower UHF/TACAN antenna. The right photo shows the location of various antennas and lights on the top of the aircraft (in this case an F-111F). The light non-standard markings behind the strip lights are the hinge line of the over-wing fairings.

Lights

Anti-collision lights were located on the top and bottom of the aircraft. On the belly they were mounted between the weapon bay and main landing gear door except in the EF-111 where it was located to the left of the UHF antenna under the nose. They were turned on and off at the same time as the ground roll spoiler switch, so were normally retracted into the fuselage and not seen on the ground.

While normally used throughout the flight, the anti-collision beacons were turned off prior to combat, automatically retracting into the fuselage. Also turned off prior to night combat were the electro luminescent ‘strip-lights’, fitted during the early 1980s to provide better visual references for night formation flying.

CM Dispensers

Chaff and flares were carried in the aircraft’s internal countermeasures dispenser set (CMDS), located in the bullet fairings for the horizontal tail. The older AN/ALE-28 dispensers were gradually replaced between 1990 and 1992 with the USAF-standard AN/ALE-40 (but few, if any Desert Storm aircraft had this modification).

The AN/ALE-28 (left) countermeasures dispenser was used by the F-111 for most of its service. At about the time of the 1991 Gulf War, the much more reliable AN/ALE-40 (right) was adopted. Generally, the AMP/Pacer Strike aircraft had this modification.

Text Copyright © 2002 Jim Rotramel
Images Copyright © 2002 United States Department of Defense and Jim Rotramel
Page Created 10 March, 2002
Last Updated 15 December, 2003
 

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