F-105 Thunderchief

The Republic F-105 Thunderchief is an American fighter-bomber that served with the United States Air Force from 1958 to 1984. Capable of Mach 2, it conducted the majority of strike bombing missions during the early years of the Vietnam War; it is the only American aircraft to have been removed from combat due to high loss rates.[1] It was originally designed as a single-seat, nuclear-attack aircraft; a two-seat Wild Weasel version was later developed for the specialized Suppression of Enemy Air Defenses (SEAD) role against surface-to-air missile sites. The F-105 was commonly known as the “Thud” by its crews.

As a follow-on to the Mach 1 capable North American F-100 Super Sabre, the F-105 was also armed with missiles and a rotary cannon; however, its design was tailored to high-speed low-altitude penetration carrying a single nuclear weapon internally. First flown in 1955, the Thunderchief entered service in 1958. The single-engine F-105 could deliver a bomb load greater than some American heavy bombers of World War II such as the Boeing B-17 Flying Fortress and Consolidated B-24 Liberator. The F-105 was one of the primary attack aircraft of the Vietnam War, with over 20,000 Thunderchief sorties flown. Out of the 833 produced, 382 aircraft were lost, including 62 operational (non-combat) losses. Although less agile than smaller MiG fighters, USAF F-105s were credited with 27.5 kills.

During the conflict, the single-seat F-105D was the primary aircraft delivering heavy bomb loads against the various military targets. Meanwhile, the two-seat F-105F and F-105G Wild Weasel variants became the first dedicated SEAD platforms, fighting against the Soviet-built S-75 Dvina (NATO reporting name: SA-2 Guideline) surface-to-air missiles. Two Wild Weasel pilots were awarded the Medal of Honor for attacking North Vietnamese surface-to-air missile sites, with one shooting down two MiG-17s the same day. The dangerous missions often required them to be the “first in, last out”, suppressing enemy air defenses while strike aircraft accomplished their missions and then left the area.

When the Thunderchief entered service it was the largest single-seat, single-engine combat aircraft in history, weighing approximately 50,000 pounds (23,000 kg).[2] It could exceed the speed of sound at sea level and reach Mach 2 at high altitude.[3] The F-105 could carry up to 14,000 lb (6,400 kg) of bombs and missiles. The Thunderchief was later replaced as a strike aircraft over North Vietnam by both the McDonnell Douglas F-4 Phantom II and the swing-wing General Dynamics F-111 Aardvark. However, the “Wild Weasel” variants of the F-105 remained in service until early 1984, at which point they were replaced by the specialized F-4G “Wild Weasel V”.

F-105 Thunderchief Combat Squadrons


Overview of TDY Thunderchief Combat Squadrons

Special modifications

Commando Nail

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 (1966–1975) dubbed “Ryan’s Raiders” starting in April 1967. Some of these aircraft were later converted to the Wild Weasel III standard.[52][53]

In an effort to thwart MiG attacks, several F-105Fs were also fitted with Hallicrafters QRC-128 communication jamming system under project Combat Martin. The North Vietnamese interceptor force followed Soviet air-defense doctrine, with pilots under rigid direction of ground controllers over radio links. The QRC-128, nicknamed “Colonel Computer”, filled up the rear cockpit of the F-105F. It bounced voice communications over the radio channel back out after a delay, resulting in an obnoxious garble. However, the first time the Combat Martin was used, the US National Security Agency (NSA), in charge of US strategic signals intelligence, ordered the Air Force to cease and desist immediately, since the NSA believed that the intelligence obtained by monitoring the channels outweighed the benefits of jamming them

Thunderstick II

Experience in Vietnam demonstrated the need for a better visual and blind bombing capability. In March 1968, the Air Force ordered development of an upgraded bombing/navigation system, incorporating a Singer-General Precision inertial navigation system, improvements to the AN/APN-131 navigation radar, and solid-state circuitry for the R-14A radar, which was redesignated R-14K. Furthermore, the digital AN/ARN-92 long-range navigation receiver replaced the problematic AN/ARN-85 receiver. The additional avionics were housed in a long, raised dorsal spine. The modified bombing/navigation system was known as Thunderstick II. F-105s with this system could achieve a bombing circular error of probability (CEP) of 50 feet (15 m) from an altitude of 15,000 ft (4,600 m). Although the first Thunderstick II aircraft flew in 1969, they were not used in Vietnam. A total of 30 F-105Ds received this modification.[56] They were initially assigned to the 563TFS/23TFW at McConnell AFB. In the summer 1972, they were all transferred to the newly reactivated 457TFS (AFRES) at Carswell AFB. This remained the only unit to fly the Thunderstick II until its retirement in 1981–82

Wild Weasel

In 1965, the USAF began operating two-seat North American F-100F Super Sabres specially equipped for Suppression of Enemy Air Defenses (SEAD) missions in Vietnam. Nicknamed the Wild Weasel, these aircraft achieved a number of victories against North Vietnamese surface-to-air missile radars. The second crew member was a Navigator trained as an Electronic Warfare Officer (EWO) to decipher sensor information and guide the pilot towards the targets.[57] However, the F-100F was an interim solution, since its limited payload often required multiple aircraft to conduct a successful strike; it also lacked the speed and endurance to effectively protect the F-105.

The resulting EF-105F Wild Weasel III[N 1] (the EF designation was popularly used but unofficial[59]) 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 May, flying their first mission on 6 June 1966,[59] with five assigned to the 13th TFS at Korat RTAFB and six more to the 354th TFS at Takhli RTAFB.[58]

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 en route.[60][61] In the fall of 1967, EF-105Fs began to be upgraded to the definitive Wild Weasel Thunderchief, the F-105G.[62]

The F-105G incorporated a considerable amount of new SEAD-specific avionics, including an upgraded Radar Homing and Warning (RHAW) system which required a redesign of the wingtips. To free outboard hardpoints for additional weapons, the Westinghouse AN/ALQ-105 electronic countermeasures were permanently installed in two long blisters on the underside of the fuselage. Thirty aircraft were fitted with pylons to carry the AGM-78 Standard anti-radiation missile. On a typical mission, the F-105G carried two Shrikes on outboard pylons, a single Standard on an inboard pylon balanced by a 450 US gal (1,700 L) fuel tank on the other side, and a 650 US gal (2,500 L) centerline fuel tank.