Republic F - 105 Thunderchief The Republic F - 105 Thunderchief was a supersonic fighter - bomber used by the United States Air Force . The Mach 2 capable F - 105 conducted the majority of strike bombing missions during the early years of the Vietnam War ; it was the only U . S . aircraft to have been removed from combat due to high loss rates . 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 F - 100 , the F - 105 was also armed with missiles and a 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 F - 105 could deliver a greater bomb load than the large strategic bombers of World War II such as the B - 17 Flying Fortress and B - 24 Liberator . The F - 105 was one of the primary strike bombers of the Vietnam War ; over 20 , 000 Thunderchief sorties were flown , with 382 aircraft lost ( nearly half of the 833 produced ) including 62 operational losses . Although less agile than smaller MiG fighters , USAF F - 105s were credited with 27 . 5 kills . During the war , the single - seat F - 105D was the primary aircraft delivering the heavy bomb loads against the various military targets . Meanwhile , the two - seat F - 105F and F - 105G Wild Weasel variants became the first dedicated Suppression of Enemy Air Defenses ( SEAD ) platforms , fighting against the Soviet - built S - 75 Dvina ( NATO reporting name : SA - 2 " Guideline " ) surface - to - air missile s . 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 . The Thunderchief was the largest single - seat , single - engine combat aircraft in history , weighing approximately . It could exceed the speed of sound at sea level and reach Mach 2 at high altitude ; The F - 105 could carry up to 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 1984 after being replaced by the specialized F - 4G " Wild Weasel V " . Development . Design phase . Republic Aviation started the Thunderchief as an internal project to replace the RF - 84F Thunderflash , which first used the characteristic wing - root air intakes to place cameras in a pointed nose . The design team led by Alexander Kartveli examined some 108 configurations before settling on a large , single - engine " AP - 63FBX " ( Advanced Project 63 Fighter Bomber , Experimental ) , specifically AP - 63 - 31 . The new aircraft was intended primarily for supersonic , low altitude penetration to deliver a single , internally carried nuclear bomb . The emphasis was placed on low - altitude speed and flight characteristics , range and payload . The aircraft would be fitted with a large engine , and a relatively small wing with a high wing loading for a stable ride at low altitudes , and less drag at supersonic speeds . Traditional fighter attributes such as maneuverability were a secondary consideration . Enthusiastic at first , the United States Air Force awarded Republic with a contract for 199 aircraft in September 1952 . However , by March 1953 , the USAF had reduced the order to 37 fighter - bombers and nine tactical reconnaissance aircraft , citing the approaching end of the Korean War . By the time the F - 105 mock - up had been completed in October 1953 , the aircraft had grown so large that the Allison J71 turbojet intended for it , was abandoned in favor of an even more powerful Pratt & Whitney J75 . Anticipating a protracted development of the engine , it was expected that the first aircraft would use the smaller Pratt & Whitney J57 . Near the end of 1953 , the entire program was canceled by the USAF due to a number of delays and uncertainties regarding the aircraft . However , on 28 June 1954 , the USAF officially ordered 15 F - 105s ( two YF - 105As , four YF - 105Bs , six F - 105Bs and three RF - 105Bs ) under the Weapon System designation " WS - 306A " . The YF - 105A prototype first flew on 22 October 1955 , with the second YF - 105A following on 28 January 1956 . In spite of being powered by a less potent J57 - P - 25 engine with of afterburning thrust ( the J75 was expected to generate with afterburner ) , the first prototype attained the speed of Mach 1 . 2 on its maiden flight . Both prototypes featured conventional wing root air intakes and slab - sided fuselages typical of the early jets ; Republic viewed the YB - 105As as not being representative of the true capability of the aircraft due to numerous changes prior to production . Insufficient power and aerodynamic problems with transonic drag , as well as Convair ' s experience with their F - 102 , had led to a redesign of the fuselage in order to conform to the Area rule , giving it a characteristic " wasp waist " . In combination with the distinctive forward - swept variable - geometry air intakes which regulated airflow to the engine at supersonic speeds and the J75 engine , this redesign enabled the F - 105B to attain Mach 2 . 15 . Into production . In March 1956 , the USAF placed a further order for 65 F - 105Bs and 17 RF - 105Bs . In order to conduct the nuclear mission , an MA - 8 fire control system , AN / APG - 31 ranging radar , and K - 19 gunsight to allow for toss bombing were integrated . The first pre - production YF - 105B flew on 26 May 1956 . Five of the F - 105C trainer variant were added to the procurement plan in June 1956 , before being canceled in 1957 . The RF - 105 reconnaissance variant was canceled in July 1956 . The first production F - 105B was accepted by the Air Force on 27 May 1957 . In June 1957 Republic Aviation requested that the F - 105 be named " Thunderchief " , continuing the sequence of the company ' s Thunder - named aircraft : P - 47 Thunderbolt , F - 84 Thunderjet , and F - 84F Thunderstreak . The USAF made the name official a month later . To fulfill the Air Force requirement for all - weather attack , Republic proposed the F - 105D variant in 1957 . It added a more advanced navigation system and improved cockpit displays for adverse weather operation . The ability to carry the TX - 43 nuclear weapon was also added . The RF - 105 reconnaissance development was also restarted , now based on the F - 105D . The first D - model took its maiden flight on 9 June 1959 . Plans to build over 1 , 500 F - 105Ds were cut short when Secretary of Defense Robert McNamara decided to equip no more than seven combat wings with the type . In November 1961 , production was cut in favor of the Air Force adopting the Navy ' s F - 4 Phantom II , and in the longer term , the General Dynamics F - 111 Aardvark of the TFX program . The final 143 Thunderchiefs built were of the two - seat F - 105F trainer variant . Based on the F - 105D , this model was 31 inches ( 79 cm ) longer to provide room for the rear cockpit ; otherwise , the aircraft had similar flight performance to the preceding F - 105D . A total of 833 F - 105s were completed before production ended in 1964 . The F - 105 had been designed for a short nuclear campaign , leading to shortcomings that became evident in a lengthy conventional war , such as a poor hydraulics layout and fuel tanks that were not self - sealing . Subsequent upgrades improved the reliability and weapons capacity of the existing F - 105Ds . In response to the surface to air missile ( SAM ) threat experienced in the skies above Vietnam , dozens of F - 105Fs were converted into anti - radar " Wild Weasel " aircraft , culminating with the F - 105G . Design . Overview . The F - 105 was a mid - wing monoplane with a 45° swept wing and tail surfaces . The single engine was fed by two intakes in the wing roots , leaving the nose free for a radome housing the multi - mode radar . Its fuselage provided room for of fuel and an internal bomb bay . The bomb bay measured by by ; it was originally to carry a single nuclear weapon but typically held an additional fuel tank . It featured four under - wing and one centerline pylon ; the two inner wing and centerline pylons were capable of accepting fuel from drop tanks . Two outer dry stations were wired for missiles or bombs . One M61 Vulcan ( initially designated " T - 171E3 " ) 20 mm 6 - barrel Gatling - style cannon was installed in the left side of the nose . A short - range AIM - 9 Sidewinder air - to - air missile could be carried on each of the outer wing pylons . The F - 105 was designed primarily for low - level interdiction and its low - altitude speed was its greatest asset when dealing with enemy fighters such as the MiG - 17 / J - 5 s and MiG - 21 . The F - 105 managed 27 . 5 air - to - air victories . Based on combat experience , the F - 105D was updated with a better ejection seat , additional armor , improved gun sights , and Electronic Counter Measures ( ECM ) pods on the wings . Flight characteristics . Former North American F - 86 Sabre pilot Jerry Noel Hoblit recalled being in awe of the F - 105 ' s size after seeing it for the first time ; he could not manage to reach the air intake lip even with a running jump . The F - 105 had a spacious cockpit with good visibility and layout ( particularly after introduction of " tape " instruments ) ; the advanced electronics were easy to learn and operate . Takeoffs and landings were often performed in the range . The spoilers provided good roll control at all speeds and the distinctive four - petal airbrakes ( which also opened slightly when the afterburner was engaged to allow for the larger flow of exhaust gases ) were highly effective even at supersonic speeds . Loss of control due to a spin or complications of adverse yaw required deliberate effort from the pilot and spontaneous spin recovery was rapid . The initial reaction of the fighter pilot community to their new aircraft was lukewarm . Between its massive dimensions and troubled early service life , the F - 105 had garnered a number of uncomplimentary nicknames . In addition to the aforementioned " Thud " , nicknames included the " Squat Bomber " , " Lead Sled " , and the " Hyper Hog " and / or " Ultra Hog " . The aircraft ' s offensive capabilities were sarcastically referred to as a " Triple Threat " — it could bomb you , strafe you , or fall on you . Positive aspects , such as the F - 105 ' s responsive controls , strong performance at high speed and low altitude , and its outfit of electronics won over some pilots . For some , " Thud " was a term of endearment ; retroactively the RF - 84F Thunderflash became known as " Thud ' s Mother " . F - 105 pilot Colonel Jack Broughton said of the nickname : " The Thud has justified herself , and the name that was originally spoken with a sneer has become one of utmost respect through the air fraternity " . 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 . 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 . Some of these aircraft were eventually brought to the Wild Weasel III standard . 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 a new bombing / navigation system incorporating a LORAN receiver , an inertial navigation system , and solid - state electronics for the R - 14A radar . Persistent problems with the AN / ARN - 85 LORAN receiver resulted in substitution of the AN / ARN - 92 . This was housed in a long , raised dorsal spine . Known as " Thunderstick II " aircraft , these F - 105s could achieve a bombing circular error of probability ( CEP ) of from an altitude of . Although the first " Thunderstick II " aircraft flew in 1969 , they were never used in Vietnam . A total of 30 F - 105Ds received this modification . 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 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 . 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 ( 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 May , flying their first mission on 6 June 1966 , with five assigned to the 13th TFS at Korat RTAFB and six more to the 354th TFS at Takhli RTAFB . 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 . In the fall of 1967 , EF - 105Fs began to be upgraded to the definitive Wild Weasel Thunderchief , the F - 105G . The F - 105G incorporated a considerable amount of new SEAD - specific avionics , including an upgraded 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 fuel tank on the other side , and a centerline fuel tank . Costs . Notes : " The costs above are in approximately 1960 United States dollars and have not been adjusted for inflation . " Operational history . Introduction . The F - 105B entered USAF service with the Tactical Air Command ' s 335th Tactical Fighter Squadron of the 4th Tactical Fighter Wing in August 1958 , although the squadron did not become fully operational until 1959 . On 11 December 1959 , an F - 105B piloted by Brig Gen Joseph Moore ( commander of the 4th Tactical Fighter Wing ) set a world record of over a circuit . Difficulties with its avionics and the MA - 8 fire - control system were experienced early on , typically the F - 105 required 150 hours of maintenance for each flying hour . Most of these problems were addressed under " Project Optimize " . The lack of spares resulted in the entire F - 105B fleet being briefly grounded in 1960 . In 1964 , modified F - 105Bs with ballast replacing the cannon , fuselage and wing reinforcement for aerobatics , and the addition of a smoke generator , briefly flew with the United States Air Force Thunderbirds demonstration team . After only six shows , a fatal accident from overstressing the airframe led to the reintroduction of the F - 100 Super Sabre . By 1964 , the F - 105B was relegated to USAF Air National Guard ( ANG ) squadrons . It was replaced in frontline service by the definitive F - 105D whose advanced NASARR R - 14A radar and AN / ASG - 19 Thunderstick fire - control system gave it all - weather capability . The R - 14A radar also added a terrain - following radar capability , while a completely new instrument panel was fitted , replacing dial - type instrument with vertical tape instruments which were easier to read in combat . In order to accommodate the new radar , with a much larger radar dish , the forward fuselage was redesigned , increasing overall length by . The F - 105D entered service with the 335th TFS in September 1960 , although it was not fully operational on the F - 105D until early 1961 . The first overseas F - 105 units formed in West Germany in 1961 , with the 36th Tactical Fighter Wing at Bitburg Air Base in May and the 49th Tactical Fighter Wing at Spangdahlem Air Base in October . Both wings had a primary tactical nuclear strike role for NATO . The F - 105D was also deployed to the Pacific , with the 18th Tactical Fighter Wing at Kadena in Okinawa converting in 1962 and the 8th Tactical Fighter Wing converting from 1963 . Like the F - 105B , the F - 105D ' s early career was plagued with maintenance problems and in - flight failures . The origins of the nickname " " Thud " " were obscure ; some claim that it stood for the sound of an F - 105 crashing into the ground . The entire F - 105D fleet was grounded in December 1961 and then again in June 1962 . Many of the issues were worked out during the production run and by 1964 , early F - 105Ds were upgraded with these fixes under Project " Look Alike " , although engine failures and fuel system problems persisted until 1967 . Meanwhile , the USAF was gradually changing the anticipated F - 105 mission from nuclear interdiction to conventional bombing . The " Look Alike " upgrades increased the aircraft ' s capacity from four to 16 conventional bombs on underwing and fuselage centerline hardpoints and added the equipment to launch AGM - 12 Bullpup air - to - ground missiles . In June 1961 , an F - 105D delivered of conventional bombs during a USAF test — at the time a record for a single - engine aircraft and a payload three times heavier than World War II ' s four - engine heavy bombers such as the Boeing B - 17 Flying Fortress and the Consolidated B - 24 Liberator , though aerial refueling would be required for long missions . One of the F - 105Ds was named " Memphis Belle II " after the famed World War II B - 17 . Vietnam War . In spite of a troubled early service life , the F - 105 became the dominant attack aircraft early in the Vietnam War . The F - 105 could carry more than twice the bomb load farther and faster than the F - 100 , which was used mostly in South Vietnam . In a foreshadowing of its Wild Weasel role , the first F - 105D combat mission of the war involved an attack on 14 August 1964 against an anti - aircraft artillery site on Plaine des Jarres . This mission was carried out by aircraft of the 36th TFS , 6441st Tactical Fighter Wing deployed from Yokota Air Base , Japan to Korat Royal Thai Air Force Base , Thailand . The first Thunderchief lost in the war also occurred during this mission , although the pilot managed to return the aircraft to Korat . The first strike mission took place on 13 January 1965 with the destruction of the Ben Ken bridge in Laos . In early 1965 additional F - 105 squadrons were deployed to Korat and Takhli air bases in Thailand . At the start of Operation Rolling Thunder in March 1965 , large numbers of F - 105Ds were shipped to these bases to participate in intense bombing missions . On 3 April 1965 , a total of 79 aircraft , including 45 F - 105 Thunderchiefs , were sent against the Thanh Hoa Bridge , nicknamed " Dragon ' s Jaw " . The next day , enemy MiGs were encountered during a second run upon the bridge ; a total of eight MiG - 17s faced 46 F - 105s escorted by a MiGCAP flight of 21 F - 100 Super Sabres . The MiG - 17s evaded the escorts using altitude and cloud cover , instead focusing upon the bomb - laden Thunderchiefs . Two Thuds were lost to the MiG - 17s ; a third , thought to be lost to groundfire , was later claimed by the North as downed by a MiG - 17 . An F - 100 claimed the only probable MiG - 17 kill , although a Vietnamese pilot believes three of his comrades were shot down by F - 105s . One F - 105 piloted narrowly escaped . USAF Chief of Staff General John P . McConnell was " hopping mad " to hear that two F - 105s had been shot down by Korean War - era subsonic North Vietnamese MiGs . The Thanh Hoa Bridge proved resistant to aerial bombing , multiple missions were flown to damage the bridge both by F - 105s and U . S . Navy aircraft . On a typical combat mission into North Vietnam , the F - 105D carried two wing - mounted fuel tanks , a fuel tank in the bomb bay , and five or six bombs , and required inflight refueling going to and sometimes returning from Hanoi distant . F - 105s flying in the vicinity of Hanoi would routinely travel around mountainous terrain nicknamed " Thud Ridge " to evade the air defenses surrounding the city . Colonel Jack Broughton , an F - 105 pilot in Vietnam , noted the demands of flying close to Hanoi gave " simply no room for error " . On 11 August 1967 , F - 105Ds from 335th Tactical Fighter Squadron with support from F - 105 Wild Weasels from 338th Tactical Fighter Squadron made the first of many successful attacks on the Paul Doumer bridge over the Red River . Flying low - altitude missions and conducting dive bombings forced the F - 105s into range of North Vietnamese anti - aircraft guns , sometimes coming under heavy fire . A combined 395 F - 105s were lost in Southeast Asia , including 334 ( 296 F - 105Ds and 38 two - seaters ) lost to enemy action and 61 lost in operational accidents . USAF F - 105s were escorted by F - 4s to protect them against enemy fighters . However , the Thunderchief was officially credited with 27 . 5 air - to - air victories against North Vietnam ese aircraft at the cost of 17 aircraft lost to enemy fighters ( North Vietnamese pilots claimed to have shot down an additional 23 F - 105s but none have been confirmed by USAF ) . All victories were against MiG - 17s . Of these 24 . 5 were shot down with cannon fire ( one victory was shared with an F - 4 ) , and three with AIM - 9 Sidewinder missiles . One F - 105F is unofficially credited with downing three MiGs — one by air - to - air missile , the second by cannon fire and the third by jettisoning the centerline rack full of bombs directly into the path of a surprised MiG . Medal of Honor recipients . Two Wild Weasel pilots received the Medal of Honor : Phase - out and retirement . As production of F - 105s had ended , the type was replaced in the Vietnam War by other aircraft , primarily the McDonnell Douglas F - 4 Phantom II . In October 1970 , the 355th Tactical Fighter Wing , based at Takhli RTAFB , Thailand , the last F - 105D unit in Vietnam , began to return to the U . S . The F - 105G Wild Weasel versions soldiered on until the end of the war . They were gradually replaced by F - 4G Wild Weasel IVs . The Thunderchief was rapidly withdrawn from USAF service after the end of the Vietnam War . Of the 833 F - 105s built , nearly 50 % were lost in Vietnam . The U . S . Air Force began transferring remaining aircraft to Air Force Reserve ( AFRES ) and Air National Guard ( ANG ) units in 1973 . By the late 1970s , these Thunderchiefs were aging and becoming difficult to maintain . The last F - 105Gs with the 128th Tactical Fighter Squadron of the Georgia ANG were retired on 25 May 1983 . The last flight of the F - 105 Thunderchief was by the AFRES 466th Tactical Fighter Squadron with F - 105Ds on 25 February 1984 .