Republic Aircraft's F-105 Thunderchief | HistoryNet
The F-105 Thunderchief was the heaviest single engine aircraft the U.S. Air Force ever flew.

Republic Aircraft’s F-105 Thunderchief

By John D. Cugini
6/12/2006 • Vietnam Magazine

It has been said that great events make great men…that extraordinary situations–wars, revolutions, disasters–offer individuals the opportunity to rise to the occasion. Applying this theory to an aircraft, the F-105 Thunderchief fighter-bomber serves as a case study in achieved greatness.

Designed under the inspired aeronautical tutelage of Alexander Kartveli, Republic Aircraft’s chief engineer, the F-105 Thunderchief, better known by its affectionate nickname ‘Thud,’ bore Kartveli’s developmental trademarks–speed, size and power. In the true tradition of its predecessors, the venerable P-47 Thunderbolt and F-84 Thunderjet, the F-105 possessed all of these attributes, plus an advanced electronic navigation and bombing package that gave it a distinct advantage over its rivals.

The Thud was first conceived as an ‘in-house’ private venture to succeed the first-line F-84 series of fighter-bombers. No less than 108 configurations were investigated by the Republic team before the basic concept was finalized as a single-seat, single-engine fighter-bomber to fill the tactical nuclear strike role. Its stated mission was to fly low level and at high speed into the Soviet homeland to deliver, with great precision, a tactical nuclear bomb housed within its internal bomb bay.

The airframe was engineered to withstand these extremely exacting requirements, incorporating a highly swept short wing and a ‘coke bottle,’ pinched-waist fuselage, and exploiting the then new ‘area rule’ concept for reduced aerodynamic drag at transonic speeds. Also incorporated were unusual forward-swept air-intake ducts located at the wing root, and a ventral fin on the underside of the rear fuselage to provide enhanced lateral stability at high speeds. The largest single-engine airplane ever built, the F-105 stood 19 feet 83/4 inches high, more than 3 feet higher than the very large, twin-engine F-4 Phantom jet. The Thud’s great size and weight demanded a powerhouse of an engine, and it got one–eventually.

Originally, the Thud was to be powered by the new and technically advanced Pratt & Whitney J-75 turbine engine, but the unavailability of that power plant necessitated the installation of the less powerful Pratt & Whitney J-57-P-25 in the two YF-105A-1-RE prototypes, the first of which flew on October 22, 1955. By the time the third aircraft was completed on May 26, 1956, Pratt & Whitney J-75s were ready for installation in the first batch of F-105s.

The J-75 packed one heck of a punch, delivering a powerful maximum static thrust of 23,000 pounds at sea level, burning JP-4 fuel at a rate of 776 pounds per minute. It represented the new generation of two-spool geometry engines, employing concentric shafts to allow the N1 and N2 compressors and turbines to operate at their respective optimum rotational speeds. Water injection was also added to increase thrust beyond that provided by afterburning. This crowned the J-75 as the undisputed king of contemporary turbine engines.

The principal outstanding feature of the F-105 ‘D’ model, the mainstay of the Thunderchief force, was its highly sophisticated, integrated electronics. The AN/APN-131 doppler navigation system would automatically supply the pilot with continual position coordinates, ground speed, wind direction, distance to target, heading and other pertinent information. The R-14A monopulse radar provided all-weather terrain avoidance for pinpoint, low-level bombing missions. The AN/ASG-19 Thunderstick fire-control system was optimized for blind or visual and manual or automatic weapons delivery.

This innovative, supersensitive gadgetry identified the Thud as the first ‘black box’ fighter and subsequently singled it out as the only aircraft capable of penetrating the equally sophisticated Soviet-supplied air defense system fortifying North Vietnam. But there were a number of ‘bugs’ that had to be worked out of its complex systems before it went to war.

Initially, the F-105 was a maintenance nightmare, and it gained a variety of dubious handles, including ‘Ultra-Hog,’ ‘Lead-Sled’ and finally ‘Thud.’ But then, slowly, specific problems were identified, classified and resolved. Maintenance personnel who until then had had little or no experience with electronic components and systems began to absorb their rudimentary fundamentals and learned the Thud’s own peculiar problems and idiosyncrasies.

With an unprecedented one-third of its total cost stemming from electronic hardware, the F-105 represented a new dimension in aircraft technology and, consequently, a true learning experience for everyone involved, from chief engineer to line mechanic. But by 1964, things were finally looking good for the new fighter. Successful deployments to U.S. and overseas air bases were taking place, the flamboyant Air Force Thunderbirds demonstration team was re-equipped with specially modified F-105B models to show off the Thud’s awesome performance envelope and gut-wrenching raw power. With increasing success, the F-105 was being integrated into America’s new supersonic, superslick, nuclear-minded air force.

Then on August 2, 1964, three North Vietnamese patrol boats attacked the U.S. destroyer Maddox in the Gulf of Tonkin. The United States was at war. As a prophetic sign of the F-105’s dominant role in the hot air war about to take place over North Vietnam, four Thuds of the 36th Tactical Fighter Squadron on temporary duty at Korat Royal Thai Air Force Base flew a rescue combat air patrol mission during that same month for a pilot shot down by the Pathet Lao over the Plain of Jars in Laos. On this first mission, F-105D No. 62-4371 became the first Thunderchief to be hit by enemy fire. It limped back to base wounded but in one piece, an indication of the Thud’s ability to withstand copious amounts of punishment and still return to base.

When North Vietnamese torpedo boats attacked two U.S. destroyers in the Tonkin Gulf that same month, the Tactical Air Command deployed its first F-105 unit to Da Nang. However, the great majority of Thunderchief units would be stationed at Thailand’s Korat and Takhli air bases, mainly because they provided ample room for growth not found in the small, crowded air facilities in South Vietnam.

There were three excellent reasons why the F-105 was chosen to bear the brunt of the intense air war over North Vietnam: speed, range and bombload. The nature of the extremely dangerous, long-haul missions into the north country demanded an aircraft of unprecedented versatility and survivability. The Thud possessed both. On a daily basis, it had to confront an unbelievably dense air-defense system designed and supplied by the Soviets and manned by specialized Chinese and North Vietnamese operators. There were hundreds of radar-directed SA-2 SAM (surface-to-air missile) sites and radar-controlled 57mm, 80mm and 120mm gun batteries too numerous to count, as well as Mikoyan-Gurevich MiG-17 and MiG-21 interceptors flown by North Vietnamese and Soviet pilots. And then there was the weather–some of the worst on the planet, including ‘thunderbumpers’ with tops reaching over 50,000 feet that could toss around a fighter like a basketball, ceilings so low and thick that punching through the underside often meant exchanging greetings with a hilltop farmer, and monsoon rains strong enough to cut visibility down to zero.

Despite the many obstacles, Thud pilots persevered. The Thunderstick bombing and navigation system that had previously caused operational headaches was now paying off–in spades. Hauling a 12,000-pound bombload, the F-105 could fly the 600-mile route to the North from bases deep within Thailand, push Mach 1 down Thud Ridge on approach to target Hanoi while skimming the terrain and dodging SAMs, MiGs and anti-aircraft artillery, and put its bombs right on the money. Kicking in the afterburner, the Thud was on its merry way back to Thailand via a rendezvous with a Boeing KC-135 tanker.

The North Vietnamese MiGs had a nasty habit of harassing Thud pilots just as they were approaching or departing the target. But at low altitude, where the F-105 was designed to operate, it could more than handle the air circus. During the course of the war, F-105 aircrews downed 271/2 MiGs, sharing one with a F-4D Phantom crew. Twenty-five of those kills were achieved with the Thud’s deadly M-61 20mm Vulcan cannon, which could spit out rounds at a fantastic rate of 6,000 per minute. The remaining MiGs were downed with AIM-9 Sidewinder missiles.

To combat the many SAM sites plaguing Thud pilots, the F-105F trainer was equipped with ECM (electronic counter measures) equipment, anti-radiation sensing devices and missiles. Dubbed ‘Wild Weasel,’ the F-105F was crewed by a pilot and an electronic weapons systems officer who locked on to radar-emitting guns and SAM batteries, countering them with radar-seeking Shrike missiles. Although the system was new and in need of continual refinement — at first, Wild Weasel crews were shot down faster than they could be formed–it proved very successful in the latter stages of the war. Today, Wild Weasels are an integral part of Air Force strike missions.

The year 1968 witnessed both the end of the Rolling Thunder bombing campaign against the North and the widespread incorporation of the F-4 Phantom into the Air Force inventory. The battle-scarred warhorse F-105s, their numbers depleted by the intensity of the northern air war, began being phased out of active duty and relegated to Air Guard and Reserve units. On May 25, 1983, the last Thud was retired from service with the Georgia Air National Guard. It was a somewhat somber occasion, shrouded in memories, but the illustrious, lone Thud stood on the line big and proud as ever, reflecting the glory of the many who flew beside her.


This article was written by John D. Cugini and originally published in the February 1996 issue of Vietnam Magazine. Read more about the F-105 here.

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17 Responses to Republic Aircraft’s F-105 Thunderchief

  1. Tom Greenwood says:

    I started with Republic Aviation in 1963 and worked there in, “08 shop”, for thirteen months on the last single seaters and then started on the two seater until I got drafted. While I was there I installed the rain remover in front of the windshield. My dad was in engineering, and now and then he would show up, talk to my foreman just to make sure I was doing the right thing. I loved it.
    I got drafted in “64” and ended up in Vietnam “65-66″. Little did I know, the plane I worked on was above my head and probably preserved my life.
    I still have my,”Kennedy box”,and different tools for the wing nuts and rivets,the pad to get authorization for tools or drills in the tool crib. Good Memories!

  2. Andrew Dougherty says:

    I am a Thud pilot
    I love my plane
    It is my body
    I am its brain

    Packed with transistors
    Black boxes diodes
    But stay alert
    ‘Cuz you might get hurt
    When she explodes


    We are the WildWeasels and north we did go to see that dude called HO. He send them up we kicked them down and in the process slaped some Migs around. Thud Ridge we did live and some died. WildWeasels first in and last out to all Thud drivers we got it right.

  4. Larry G. Mitchell says:

    I was the laod crew jammer driver in the first group of guys to
    come down to Korat from Kadena in May of 1966. Spent a year of
    my young life loading at Korat. It was tough and hot in Thailand
    that year, but I would not trade that time period in my life for
    anything! I am proud to have served the 13 TFS Wild Weasels
    panther Pack!!! Hoo-rah! Larry the Loader!

    • John Cotseres says:

      Someone told me you had two air force patches for sale.
      1. the 100 MISSION patch / 2. says at top “421 TFS” and at bottom “READDY WILLING ABLE” it also has a SWORD and HAT” on it.
      I will pay you $100.00 for each of these patches. / I am a collector of Vietnam war patches. Lt Col Robert E Phillips wore these patches, he was leader of A-Flight, he flew bombing missions over North Vietnam in 1966 out of Korat AB.
      Please let me know if you want to sell these patches?

  5. Jim Hill says:

    Spent 13 years with the 113th CAMS at Andrews, and served as a Instrument/Auto-Pilot and Doppler Radar tech. The avionics on that airplane can probably be duplicated in a box the size of an iPod today, but we found out eventually with similar technology the avionics in Gulf War aircraft actually all worked. I spent a good part of my military career walking the flight line at Andrews, and the electronics training the Air Force gave me has provided me with a career that is lucrative to this day. I was never able to serve in combat as a lot of my Thud Fixer brethern (and ladies – in the Guard – believe it or not!). But this airplane and the folks who kept her eyes sharp, her aim true and her thunder in the air will never forget her. Hell, on deployment to McDill AFB in 1983, we put 44 sorties a day in the air with 17 aircraft, while our regular Air Force pals could not get 20 F-4s off the ground with 77 airplanes to choose from. Go figure.

  6. Wayne "Gill" Gilliland says:

    My year with the 333rd TFS was the best year of my life. I only wish I had extended another year. Takhli RTAFB was in the middle of no where. I was a bomb load crew chief. It was a job that I was real good at. Later with the Reserves I worked on F-4s, what a peace of junk! When you were under tha F-4 loading you were subjected to Phamton Bites. This junk had little bleader vents everywhere and they would split you head wide open. We had a hard time keeping enough aircraft operational. We had one that we named Aronald (after the pig on Green Achers). It was our hanger queen. We even made T-shirts with a crew chief in front of the F-4 with an ear of corn in each hand trying to get Aronald to come out of the hanger.

  7. Joe Catania says:

    I worked at Republic Aviation in the early sixties 19 year old kid I worked with only 4 other guys stevie,mike,another Joe and a kid who I can not remember his name. We were in a special classification call edTINY TIMS we installed the smallest fuel cell the 3D cell in the rear just before the tail . We would go out to Flightline to repair some cells before they left I think for Oklahoma. It was one of the most interesting and gratifying jobs I ever had. Hope all the other Tiny Tims are doing good. GREAT AIRCRAFT!!!

  8. ELIAS B. LARKIN says:


  9. Dennis Bridgford says:

    I was with the 355th TFW, PCS George AFB, McConnell AFB, TDY to Korat and PCS to Takhli in 1963/66. Parachute shop. I packed thousands upon thousands of F105 drag chutes. Awesome aircraft. I now have retired to live in Korat Thailand 4 years ago.

  10. Bil Nelson says:

    I was a Mechanical Accessories guy., and received my initial training on the Thud at Nellis AFB, NV, in Juily 66. 30 days later at Takhli. Keeping the F-105 flying became and still are my finest memories. A Great Aircraft.keep more

  11. Rtchard E Bondanza says:

    I work for Republic a short time I did the 109 door right wing leading edge,fitted,cut ,installed loved it my number 81671 is in all right doors I built .contract was cut I went in army Iam 78and very proud to be part of this great under rated aircraft. sincerely.R. E Bondanza

  12. Ben Kendig says:

    Have been looking for pictures and information on the F-105D
    doppler navigation system. It was made by LFE in Boston.
    My job was to service this system. I spent 18 months in Kessler tech school.
    Later stationed in Karat during Rolling Thunder.
    Just nostalgia.
    1964 THRU

    • Ray Park says:

      Ben (and others)
      Guess you’ve seen my post, previous to yours. I was retraining into Airborne Nav Aids when I was picked for Doppler school. I still remember we had to take a short test on digital logic to try for this. I was an E4 and you had to be an E4 over 4years to get the government to move you if you were married and the Doppler school put me over four. I spent 15 weeks in Doppler school.
      The APN 131 was a follow on to the APN 105 which was eventually only used for ballast. Occasionally, believe it or not, some pilot would turn it on and it sometimes would actually work. You’re right, the system was made by Laboratory For Electronics in Boston. In Japan, we had a Tech Rep from the factory.
      I also remember that it took 13 cables to connect the “Lift”(an outstanding piece of test equipment) to the bird. Even recall remembering running the programs for a simulated flight, One time when running a ground power unit, it started smoking badly. Turned out that diesel fuel was leaking out onto something hot. I got down from the cockpit and guided the self propelled unit off the runway and away from the plane. The smoking quit shortly after turn off.
      Fuse 01 was for 28 VDC and would kill the entire system.
      Do you remember the “hat checks”? Or the fact that the system was very sensitive to cooling duct leaks? All those cards in the PPC (Present Position Computer)?
      I would like to communicate with anybody associated with the F-105 and/or the Doppler System. Thanks Ray

  13. Dan Riesel says:

    I was a line mechanic on the F-105D&F models at Spangdahlem,AB,Germany in 1965-67.Also was TDY to Wheelus AB,Libya 4 times as support for them.Went to Torrejon AB Spain where we sent Thuds to US to be sent to VietNam.I was at Nellis AFB,Nev.1963-65 and used to watch the Thunderbirds fly the F-105 until Capt.Devlins plane disintegrated from lack of oil when flying inverted.They went back to the F100s after that.

  14. Ray Park. MSGT, Retired says:

    This brings back a lot of memories. I worked on the AN/APN 131 Doppler Radar Navigation Equipment, both flight line and field shop, for approx 7 and a half years. Back then, that \F\ prefix, given to your AFSC, pretty well assured you would be staying with the bird through future assignments. I was assigned to Yokota AFB, Japan, Korat RTAFB, Takhli RTAFB and McConnell AFB, Kansas plus TDYs to Osan AFB, Korea and George AFB, California.
    Later in my AF career, I taught in the 9 Level Avionics Course at Lowry, AFB.
    Then I did another 20 years for the AF as a civilian, teaching Electronics Fundamentals, PMEL and Space systems. I am now retired, living in Aurora, CO. Thanks Ray

  15. Duane Mitchell says:

    I was on a Weapons Load Team in the 13TFS at Korat RTAB from May 1966 to June 1967. The great Republic F-105 Thunderchief (THUD) was the best aircraft a weapons loader could hope for. Nice high wings and good clearance at the centerline MER weapons racks made loading weapons a pleasure as compared to many other aircraft. My time at Korat RTAB with the F-105 was a time that I have treasured and remembered all of my life, and memories of the Thunderchief are equally treasured. During my tour there, I kept a daily log of the weapons my team loaded and the aircraft they were loaded on. I still have that log.

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