Special modifications

The rear cockpits of several two-seat F-105Fs were modified under project Commando Nail with an R-14A radar and a radar scope that offered high resolution. These aircraft were used for all-weather and night low-level strikes against especially dangerous targets by a unit from the 13th Tactical Fighter Squadron dubbed "Ryan's Raiders" starting in April 1967. Commando Nail aircraft were also used to develop tactics for proposed B-58 Hustler bomber missions in Vietnam, although the Hustler was never deployed to Southeast Asia. Some of these aircraft were later converted to the Wild Weasel III standard.

F-105F-1-RE Thunderchief, SN: 63-8339, later converted into a F-105G.

Persistent problems with the AN/ARN-85 LORAN system resulted in 30 F-105Ds being upgraded to the AN/ARN-92 in a long dorsal spine. Known as Thunderstick II aircraft, these F-105s could achieve a bombing circular error probable of 50 feet (15 m) from an altitude of 15,000 feet (4,570 m). Although the first of these aircraft flew in 1969, they were never deployed to Vietnam.

Wild Weasel

In 1965, the USAF began operating two-seat F-100F Super Sabres specially equipped for Suppression of Enemy Air Defenses mission in Vietnam. Nicknamed the Wild Weasel, these aircraft achieved 9 confirmed victories against North Vietnamese surface-to-air missile radars. The second crew member was an Electronic Warfare Officer, nicknamed the Bear(as in trained bear), whose job was to decipher the information from the aircraft's sensors and guide the pilot towards the targets. However, the F-100F was an interim solution and because of its limited payload it usually had to rely on accompanying strike aircraft to actually attack the SAM sites. It also lacked the speed and the endurance to effectively protect the USAF's primary strike fighter — the F-105. With twice the payload capacity of the Super Sabre and considerably better performance, the two-seat F-105F was an ideal candidate for a more definitive SEAD platform.

The resulting EF-105F Wild Weasel III (the EF designation was popularly used but unofficial) supplemented its sensors and electronic jamming equipment with AGM-45 Shrike anti-radiation missiles and conventional bombs, giving it an offensive capability lacking in the F-100F. The first of these aircraft flew on 15 January 1966 and they began arriving in Southeast Asia in June, with five assigned to the 13th TFS at Korat and 6 more to the 354th TFS at Takhli. In a typical early mission, a single EF-105F would accompany one or two flights of F-105Ds to provide protection from enemy ground fire. While this strategy was effective in reducing F-105D losses, the Weasel aircraft suffered heavy casualties with five of the first 11 lost in July and August 1966. Attacks into high-risk environments saw the Weasels operating in "Iron Hand" Hunter-Killer flights of mixed single-seat and two-seat Thunderchiefs, suppressing sites during attacks by the strike force and attacking others during ingress and egress.

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