Sunday, October 27, 2013

USAF F-4 Wild Weasel Aircraft before the F-4G



As the air war in Vietnam heated up, and the Soviet Union started supplying the North Vietnamese armed forces with better air defenses, the US Air Force realized the need for what became known as Wild Weasel aircraft to help suppress the SAMs.  Their first attempt was the F-100F Wild Weasel I aircraft.  While the F-100F was successful in suppressing SAM activity, it had one glaring weakness - speed.  The F-105s that were carrying out the bombing campaign found themselves flying very slow so they didn't out-distance the F-100s that were providing them protection.

A newer airframe was needed, one that could keep pace with the fighter-bomber formations without effecting their performance.  The two airframes that were available at the time were the F-105 Thunderchief and the F-4 Phantom II.  So the US Air Force initiated parallel programs fitting the Wild Weasel electronic suites into both aircraft.  This decision was based on the fact that there were a finite number of F-105s available as production had been closed on that aircraft, but the F-4 was still in production and could make up for combat loses with new aircraft.  This decision was to prove to be a very wise one.


(E)F-4C Wild Weasel IV

The first flight of a Weasel EF-105F took place on 15 January 1966, with first flight of a Weasel F-4C expected to take place six months later in July of the same year.  But the F-4C conversion was very protracted and was beset by one problem after another.  The first problem was simply one of space.  While the F-105 and F-4 were roughly the same size, the F-105 was a single engine aircraft where the F-4 with its two engines needed more real estate for fuel lines, control lines, and electronics just to operate. In short, the Phantom was a jam-packed aircraft and simply could not handle the added electronics and wiring required to properly install Wild Weasel equipment without some major revisions.

The (E)F-4C Wild Weasel went through several versions during development.  The first - Wild Weasel IV-A was a pod mounted system in the starboard rear missile well.  All of the Sparrow launch equipment and wiring were removed and replace with the necessary electronics and wiring for the Wild Weasel mission.  Itek/ATI APR-25 and -26 RHAW  equipment was installed and a IR-133 Panoramic Receiver was put in the pod.  Sounds nice, but it didn't work, there was high interference coming from someplace and it gave either erratic displays or no display at all.  For a year the engineers beat their collective head against the wall, trying to  understanding how the same system that worked well in the F-100F and EF-105F resulted in nothing but problems on the F-4.  Finally Mr. C.K. Bullock the brain-child of the Wild Weasel I system installed in the F-100F was brought in as a consultant and he spotted the problem right away. The F-100 and F-105 both used low-capacitance coaxial cable to carry the video information to the RHAW scopes to match the low-capacitance wiring of the of the aircraft. The F-4, on the other hand, used high-capacitance wiring on its systems so they had used high-capacitance wiring to incorporate the Wild Weasel installation.  The equipment wasn't designed for that.


With this problem solved, McDonnell began flight tests of the Wild Weasel 4, but further problems with vibration in the pod caused erratic displays, again delaying the program. Meanwhile EF-105F Weasels were already in combat and were achieving a lot of success. It became obvious to McDonnell Engineers that somehow the system would have to be mounted internally.

McDonnell engineers began working feverishly on Project Wild Weasel IV-C, the reengineering effort to make room in the F-4C for the Wild Weasel components. Finally, in June of 1968, almost two years after the scheduled deployment of at least four (E)F-4C Weasels, the installation of the electronics in their new internal spaces was begun!  The new installation worked as advertised and the first operational (E)F-4C Wild Weasel was delivered to the 67th TFS based at Kadena AB, ROK on October of 1969. 


By this time is seemed that the Vietnam War was winding down and the EF-105Fs seemed to have things well in hand, so the (E)F-4Cs were not needed. But, the 67th TFS (E)F-4Cs would get a crack at combat. Because of the North Vietnamese Easter Offensive in 1972, President Nixon ordered a full resumption of bombing military targets in North Vietnam. Many more aircraft were committed to LINEBACKER operations than before and the sole Wild Weasel EF-105F unit in SEA could not handle the increased mission load. In October of 1972, the 67th TFS was alerted for combat duty and was sent TDY to Korat, Thailand, just in time for the LINEBACKER II maximum effort in December. The (E)F-4Cs performed admirably while flying over 460 missions

(E)F-4C Wild Weasel IV-C of the 67th TFS
The Wild Weasel (E)F-4C could be distinguished from a standard fighter only by the additional antennas on the aircraft. Around the nose at forty-live degree positions, were the four diamond-shaped homing antennas for the ER-142. Under the nose are a short blade antenna for the APR-26, and the two small stub omni antennas directly in front of the nose gear wheel well are for the ER-142. Above the wing/fuselage juncture the raised square patch with a six inch black circle is the ER-142 direction finding antenna. The antennas for the APR-25are found inside the chin fairing under the radome, and in a fairing on the trailing edge of the vertical fin. The rear cockpit was extensively modified with the upper right corner of the rear instrument panel being taken up with RHAW scopes and Threat Display Panels.

Thirty-six (E)F-4Cs were eventually modified to Wild Weasel IV-C specifications, twelve were assigned to the 67th TFS, Kadena AB, ROK; twelve to the 81st TFS, Spangdalem, West Germany; with the final twelve being assigned to the 35th TFW at George AFB, California - the new home of the Wild Weasels.

The (E)F-4C Wild Weasel was a very successful conversion once all the bugs were ironed out.  But not every weapon system is flawless.  The one glaring weakness with the (E)F-4C was the lack of the ability to use the AGM-78 Standard ARM missile.



(E)F-4C Wild Weasel IV-C of the 81st TFS

 

(E)F-4D Wild Weasel IV-B

There were two F-4Ds modified for the Wild Weasel mission under Project Wild Weasel IV-B. Both aircraft (65-657 and 65-660), were used to test the Bendix APS-107 Radar Homing and Warning (RHAW) system with an ER-142 panoramic receiver. Although the APS-107 gear was more sophisticated and accurate than the APR-25/-26 units and finally gave the (E)F-4 the ability to use the AGM-78 Standard ARM, it proved unreliable and erratic under combat conditions - at least for the Wild Weasel mission.

Several standard F-4Ds were used to test other programs relative to the Wild Weasel mission. One aircraft (65-0644) was used to test the AGM-78 Standard ARM missile, and several F-4Ds were used to perfect the AGM-65 Maverick missile.

(E)F-4D Wild Weasel V Test Platform

 At least two F-4Ds (66-7635 and 66-7647) were modified and equipped with the new McDonnell-Douglas designed APR-38 Warning and Attack System, the basis of the entire F-4G program. 

Originally, the F-4G program had originally been slated for installation in ninety F-4Ds, but the Air Force opted for the more modem F-4E.  This decision was made because the F-4E had much more internal volume available (especially once the gun was removed) and it was considered the cheaper option because the F-4E aircraft were much more up to date than the F-4Ds which would have to be brought up to the current state of the art. This was apparent in testing the (E)F-4D test aircraft which had to carry much of the electronics in a special canoe fairing which took the place of the port/forward missile launcher because of the lack of space.

The (E)F-4D Wild Weasel aircraft never progressed farther than a test platform for the Wild Weasel V electronics, so none entered active service in any USAF squadrons. 


(E)F-4D Wild Weasel Testbed



References:

  1. Drawings (c) by Kim Simmelink
  2. Wild Weasel - The SAM Suppression Story, by Larry Davis
Revisions:

10/27/2013 - Original Post