Republic F-105D Thunderchief

Last revised May 12, 2005



The F-105D was the major production version of the Thunderchief series. It was essentially an all-weather version of the basically day-only F-105B.

In November 1957, the USAF had revised GOR 49, calling for an all-weather version of the Thunderchief to follow the F-105B. This was to be designated F-105D. In addition, the F-105D was to be capable of carrying the new Mk 43 nuclear weapon on either centerline or inboard underwing pylons.

Externally, the F-105D differed from the F-105B in having a slightly longer and wider nose, which housed the AN/ASG-19 "Thunderstick" fire control system. This was designed to meet the all-weather requirement specified in the November 1957 revision of GOR 49. The AN/ASG-19 was designed around the NASARR R-14A all-purpose monopulse radar. This radar was optimized in both air-to-ground and air-to-air modes and was capable of performing both low-level and high-level missions. This system had a ground an contour-mapping feature. The aircraft was equipped with a General Electric FC-5 flight control system which operated in conjunction with the R-14A radar to provide the F-105D with full all-weather capability. The system comprised a toss bomb computer, a sight system, an AN/APN-131 Doppler navigator, an air data computer, missile launch computer, autopilot, and search and ranging radar. The radar installation also incorporated a terrain guidance mode which permitted the pilot to let down through bad weather in unfamiliar territory and to hug the ground in order to avoid detection.

The F-105D was powered by a higher-thrust J75-P-19W engine equipped with water injection. This engine offered 1000 pounds more thrust than the P-19 engine of the F-105B. In order to provide the increased airflow required by the more powerful engine, the interior contours of the air intakes and ramps were redesigned, and the air data computer had to be reconfigured. The plumbing for the water injection system required some redesign of the rear fuselage.

A new cockpit was provided with a new instrument panel with many of the old circular dials replaced by vertical "tape" instruments, which were easier to read.

With all of this new equipment, the F-105D was over 1000 pounds heavier than the F-105B. The higher gross weight of the F-105D required the provision of a stronger main landing gear and more robust brakes.

Externally, the F-105D could be distinguished from the B by its longer and wider nose (the D about 15 inches longer than the B) with the larger radome for the NASARR radar. The F-105B carried only a simple radar ranging sight for its cannon, so its radome was considerably smaller. In addition, the F-105D had a pitot tube mounted on the extreme tip of the nose rather than at the wingtip as it was in the F-105B. The two aircraft were otherwise quite similar.

The F-105D had an arrester hook mounted on the rear of the ventral fin. This hook was intended to engage a wire in case the aircraft overshot the end of the runway during a landing. The Thunderchief was certainly NOT ever intended for carrier-based operations. :-)

The first F-105D (58-1146) flew on June 9, 1959 with Lin Hendrix at the controls. The first F-105D was accepted by the TAC at Nellis AFB on September 28, 1960. The initial contract for 59 F-105Ds was increased to nearly 300 by the end of 1961. Ultimately, 610 F-105Ds were built, making it the major variant of the Thunderchief. At one time, there were plans to build over 1500 F-105Ds, but the advent of the F-4 Phantom led Secretary of Defense Robert McNamara to decide to equip no more than 7 combat wings with the F-105D, cutting the eventual production to about half of that originally planned.

The first unit to receive the new F-105D was the 335th Tactical Fighter Squadron of the 4th Tactical Fighter Wing, which exchanged its older F-105Bs for the new D-model in June of 1960. These planes were essentially flight test machines and did not have much of the equipment that was planned for the F-105D The 335th was again forced to carry out part of the evaluation program with the F-105D, just as they had with the B. The Thunderchief's first European deployment came in May of 1961, when the 36th TFW based at Bitburg in Germany received its first F-105Ds. It was soon followed by the 49th TFW. F-105Ds were also supplied to the 4520th Combat Crew Training Wing based at Nellis AFB plus the 36th TFW (22nd, 23rd, and 53rd Squadrons), the 49th TFW (7th, 8th, and 9th Squadrons), the 18th Fighter Bomber Wing (12th, 44th, and 67th squadrons), the 355th FBW (354th and 357th Squadrons), and the 388th TFW. The 36th and 49th Wings went to Europe at the end of 1961 to provide NATO with nuclear strike capability. The 8th and 18th Wings were stationed in Japan from 1962 onwards.

In June of 1961, the F-105D demonstrated its ability to carry and deliver seven tons of bombs during special tests at Eglin AFB in Florida. This was the heaviest load of bombs ever carried by a single-engined fighter. This feat was repeated in October of 1961 at Fort Bragg, North Carolina, with President Kennedy being one of the eyewitnesses.

All F-105Ds were briefly grounded in December 1961 after the aircraft's main fuselage frame failed during a laboratory fatigue test at Wright-Patterson AFB. However, subsequent tests indicated that the frame had still retained considerable strength even after cracking. Republic had suitable adapters and tools to do the required corrective work, so the grounding was relatively brief.

A strike at the Republic plant lasting two and a half months in the spring of 1962 resulted in additional delays in F-105D deliveries. A Taft-Hartley injunction ended the strike on June 18, but production was delayed sufficiently to disrupt USAF service plans.

In June of 1962, there were two major accidents at Nellis AFB, and all F-105Bs and Ds were once again grounded, this time for replacement of chafed electrical wires and the correction of flight control deficiencies. In addition, it was discovered that several inflight failures had been caused by moisture getting through seals and disrupting electronics and avionics. This maintenance and upgrade project was known under the code name Look Alike. The project started in mid 1962, but it turned out that these modifications took a lot longer than expected, and were subsequently expanded in scope to include a bringing of all available F-105D aircraft up to F-105D-25-RE standards. This quadrupled their conventional weapons capacity, increasing it from four to sixteen 750-pound bombs. Wiring and control equipment were added for carrying and launching Martin AGM-12B or C Bullpup air-to-surface missiles. A tailhook was installed under the fuselage for short or rough-field operations. Another innovation which helped to alleviate the moisture problem was to apply a layer of silver acrylic paint to the entire surface of the aircraft. These modifications were not fully completed until mid-1964.

The F-105D was originally intended for the nuclear strike role, with the primary armament being a "special store" (a euphemism for a nuclear weapon) housed in the internal weapons bay. This weapon was usually a Mk 28 or a Mk 43. However, an Mk 61 could be carried underneath the left or right inboard underwing pylon and a Mk 57 or a Mk 61 could be carried underneath the centerline pylon. However, as nuclear war became less and less likely, the nuclear weapon carried in the internal weapons bay was usually replaced by a 390-gallon internal fuel tank, the offensive load being carried on four underwing pylons and on a pylon mounted underneath the fuselage on the centerline. From the F-105D-20-RE production block onward, the Thunderchiefs had increased emphasis on conventional weapons delivery, with the capability of carrying a wide-ranging combination of external stores underneath the wings and fuselage. Many of the earlier production block F-105Ds were eventually upgraded to this standard.

At the time of the design of the F-105, TAC was equipped with hose-and-drogue tankers such as converted KB-50s, whereas boom tankers such as KC-97s and KC-135s had been assigned to SAC. In order that it be capable of being refuelled in midair by the KB-50 fleet, the F-105 was fitted with a retractable midair refuelling probe which swung outward from a slot in the forward fuselage just ahead of the cockpit. Unfortunately, the retirement of the KB-50 tankers left TAC dependent on SAC's boom tankers. Although a hose extension could be attached to the end of the flying boom of the KC-135 so that it could handle probe-and-drogue receiving aircraft, it was thought that it would be beneficial for TAC to have aircraft that were fully compatible with SAC booms. Consequently, the last few F-105Ds off the production line (production block -31) were given the capability of refuelling from either a flying boom or a hose-drogue type of tanker. This was done by fitting a flush-mounted retractable door-type receptacle in front of the windshield which could accept a flying-boom type of midair-refuelling probe. Some earlier F-105Ds were retrofitted with these receptacles.

In service, the seven TAC wings using the F-105D experienced lots of accidents and operational problems which led to no less than ten groundings. The aircraft came to be known under the rather derogatory nickname "Thud", and had a questionable reputation for being too heavy, having too long a takeoff run, and being a maintenance nightmare. All throughout the early and mid-1960s, the F-105D continued to experience a series of accidents due to engine failures, fuel leaks, and malfunctions of the fuel venting system. These problems were not fully corrected until 1967.

The F-105D was destined to become a major participant in the war in Vietnam. In response to the Tonkin Gulf incident, the PACAF sent eight F-105Ds from the 18th TFW from Yokota from Yokota AB in Japan to Korat RTAFB in Thailand. The first action took place when aircraft from the 36th TFS flying a rescue mission over Laos attacked a antiaircraft site in the Plaine des Jarres. F-105D 62-4371 was hit by ground fire, but the pilot managed to eject safely and was recovered.

On January 13, 1965, sixteen aircraft from the 44th TFS and 67th TFS destroyed a bridge at Ben Ken in northern Laos with 750-pound bombs and AGM-12B Bullpup missiles.

On March 1, 1965 Operation Rolling Thunder began, which was the systematic bombing of North Vietnam that was destined to last until 1968. On March 2, F-105Ds from the 67th TFS bombed an ammunition depot at Xom Bong, 20 miles north of the DMZ. After a series of TDY deployments to Korat and Tahkli, two large F-105D wings were set up in Thailand--the 355th TFW which moved from McConnell AFB to Tahkli in August 1965 and the 388th TFW which moved to Korat in April of 1966 to replace the temporary 6234th TFW. The 355th and 388th Tactical Fighter Wings based in Thailand used the F-105D to carry the brunt of the air war to North Vietnam.

The Thunderchief made an excellent tactical bomber. The internal bomb bay had originally been designed with nuclear weapons in mind, but for operations in Southeast Asia, the internal bay of the F-105D rarely carried any ordnance, usually being fitted with a 365-gallon auxiliary fuel tank. With the exception of the ammunition for the M61A1 cannon, all the ordnance was carried externally. With multiple ejector racks the F-105D could carry an impressive load of external fuel, ECM gear, and up to eight 750-pound bombs on long-range missions. On short-range missions, it could carry sixteen 750-pound bombs. Alternative combat loads were two 3000-pound bombs or three drop tanks. On a typical mission over North Vietnam, the F-105D would carry six 750-pound bombs or five 1000-pound bombs, along with two 450 US-gallon drop tanks. The D could also carry the Martin AGM-12 Bullpup air-to-surface missile, but this weapon was to prove almost useless in Vietnam against hardened targets. The F-105D could carry 2.75-inch rocket pods, napalm canisters, as well as four AIM-9 Sidewinder infrared homing air-to-air missiles. The M61A1 Gatling-type 20-mm cannon proved invaluable in the dual role of air-to-air combat and ground strafing. With its size and range, the F-105D could carry twice the bombload further and faster than the F-100.

However, the F-105D was somewhat less successful as a fighter, often being hard pressed by enemy MiG-17 and MiG-21 fighters. It had a wing loading that was much too high for it to be able to maneuver effectively against the more nimble MiGs. Since all the ordnance was carried externally, maximum performance could only be reached once the bombs and rockets had been released and the aircraft was departing the target. However, when jumped by MiGs, the enormous thrust of the J75 engine enabled a cleaned-up Thunderchief to go supersonic "on the deck", quickly leaving its pursuers behind in a cloud of half-burned kerosene. When forced to fight, the F-105D did manage to shoot down 27 1/2 enemy fighters during the course of 1966 and 1967. Most of these kills were by the 20-mm Vulcan cannon, although two were downed by Sidewinders. On the other side, seventeen F-105s claimed by the North Vietnamese to have been downed by MiGs have been correlated with known USAF air-to-air losses. North Vietnam also claims that an additional 10 F-105s acknowledged by the USAF to have been lost to ground fire or other causes were actually lost to MiGs, plus another 13 where no loss has been acknowledged by the USAF.

Strikes against targets near Hanoi involved 1250-mile round trips from Tahkli. The high ambient temperatures which usually existed in Thailand degraded takeoff performance, which often required departures with less than maximum fuel load, while climb to altitude in the hot, thin air resulted in higher fuel consumption. Consequently, F-105Ds operating out of bases in Thailand usually had to be refuelled in the air by KC-135s over Laos before crossing into North Vietnam. This refuelling operation often had to be repeated on the way back, especially if afterburners had to be used to evade enemy defenses. On occasion, KC-135 tankers would take extra risks and penetrate into North Vietnamese airspace to come to the rescue of F-105Ds short on fuel or suffering from battle damage. Many an F-105 pilot escaped being an unwilling guest in the "Hanoi Hilton" because of the courage and skill of these KC-135 crews.

When approaching Hanoi from Thailand, the F-105Ds had to cross "Thud Ridge", the name given by Thunderchief pilots to a series of hills located between the Red and Black Rivers. Once over "Thud Ridge", the F-105s would approach their targets low and fast, an environment in which the F-105D excelled. Maneuverability and stability during low-level, high-speed flight were excellent due to the aircraft's high wing loading.

Throughout the Southeast Asia War, the F-105D was repeatedly modified to meet changing conditions. Many F-105Ds were retrofitted with armor plating, backup flight control systems, X-band beacons, new radar altimeters, and AN/ASG-19 Thunderstick gun bombsights which provided for automatic or manual and blind or visual weapons delivery, with automatic or manually-controlled weapons release.  Initially, the hydraulic system was extremely prone to failure due to combat damage.   A single lucky hit in a vital area could take the whole flight control system out, resulting in the loss of the entire aircraft.  The hydraulic system was made more redundant and armor was added to critical points--once it was improved the F-105D could take severe battle damage and still keep flying.  The pilot ejector seat was improved, and AN/APR-25(U)-26(V) radar homing and warning (RHAW) antennae were added to the tip of the vertical fin to help warn the pilot when MiGs were sneaking up on his tail or when a SAM was about to be launched. In addition, the refueling probes of the early F-105Ds were brought up to later standards. Several F-105Ds were provided with a combat camera mounted in a protrusion on the lower nose just behind the radome. Many F-105Ds were fitted in the field with ram air intake scoops on the rear fuselage to address an afterburner cooling problem which had resulted in some engine fires. Unfortunately, heat and high humidity often played havoc with the reliability of delicate electronic systems, with failures all too often occurring just as the aircraft was approaching its target.

Camouflage was reintroduced in 1965 on the F-105 and other high-flying tactical aircraft in order to hide them from high-flying enemy interceptors. The entire F-105 fleet and all other tactical aircraft in the USAF, both in the Southeast Asia combat zone and at bases in the USA and Europe were painted in dark green (FS 34079), olive green (FS 34102) and tan (FS 30219) on their upper surfaces and in light grey (FS 36622) on the underside.

All throughout the 1960s, the AN/ARN-85 LORAN system of the F-105D had caused severe problems during combat because of its poor reliability. In 1969, 30 F-105Ds were re-equipped with AN/ARN-92 LORAN equipment for more precise navigation. These planes could easily be identified by the presence of a long dorsal spine extending all the way from the canopy to the tail fin. They were known as Thunderstick IIs, or T-Stick II for short. With the Thunderstick II, a bombing accuracy as small as 50 feet could be obtained from an altitude of 15, 1000 feet. The first T-Stick aircraft flew on August 9, 1969. They served with the 23rd TFW in the continental US, but never saw any combat. When the F-105 was transitioned into the Air National Guard/Air Force Reserve, the Thunderstick II F-105Ds were transferred to the 457th TFS of the Air Force Reserve at Carswell AFB in Texas. They stayed there until January of 1980, when they replaced by F-4DS

The most famous F-105D raid occurred on August 2, 1967, when pilots of the 335th and 388th TFS attacked and heavily damaged the Paul Doumer bridge north of Hanoi. This bridge was vital for moving war supplies between China and North Vietnam, and was a prime target. However, the bridge was eventually repaired. Nevertheless, it was hit and knocked down again--several times.

The weapons available before the era of laser-guided "smart" bombs required delivery from low altitude or from a shallow dive, which brought the F-105Ds within range of densely-concentrated North Vietnamese AAA, and losses were heavy. The high attrition rate of F-105Ds in Southeast Asian operations soon became a problem. The conversion of USAFE units to the F-4D Phantom enabled some of the European-based F-105Ds to be transferred to Southeast Asia, but this was not sufficient to offset the heavy attrition rate. At one time, serious consideration was given to reopening the Thunderchief production line at Farmingdale to make up for the losses. However, by this time the Air Force was thoroughly committed to the F-111 and the F-4, so this was not a politically-feasible option. As more and more F-4s entered service with the Air Force, the Phantoms began to take over more responsibility for attacks on targets in North Vietnam. By 1969, the F-4 Phantom had taken over the primary responsibility for bombing raids over North Vietnam, with the F-105D being restricted to targets in Laos where the anti-aircraft fire was less intense. In 1969, the 388th TFW gave up its F-105Ds and the 355th TFW returned with its aircraft to the USA in November of 1970, bring to an end the combat use of the single-seat Thunderchief.

Over 20,000 combat missions were flown by Thunderchiefs in Vietnam. A total of over 350 Thunderchiefs (Ds and Fs) were lost in combat, most of them to North Vietnamese anti-aircraft fire. This was over half of all Thunderchiefs built. 126 F-105s were lost in 1966 alone, 103 of them to AAA. At one point in 1965-1968, it was calculated that a F-105 pilot stood only a 75 percent chance of surviving 100 missions over North Vietnam. Although the total number of losses was rather high, the actual loss rate was not that bad considering the total number of missions that were flown.

Following their withdrawal from Southeast Asia, the few Thunderchiefs to survive combat in Vietnam served with active duty Air Force units for a couple more years, primarily with the 23rd TFW at McConnell AFB and with the 18th TFW at Kadena AB on Okinawa. Beginning in 1971-1972, some of these aircraft were handed over to units of the Air National Guard, which continued to operate them until 1983, when the last example was retired. Other F-105Ds were transferred to the Air Force Reserve. The Air Force Reserve acquired its first F-105Ds in July of 1972. The last Air Force reserve unit to operate the F-105D, the 466th TFS of the 508th TFW, made the last flight with the type on February 25, 1984.

Following their withdrawal from Air Force Reserve and Air National Guard service, surviving F-105Ds were delivered to the boneyards at Davis-Monthan AFB, where most of them were scrapped. A few ended up being turned over to museums. None are still flying today.

The following Air Force units flew the F-105D:

The following Air Force Reserve squadrons were equipped with the F-105D:

The following Air National Guard Squadrons flew the F-105D:

Perhaps because of its complexity and high cost, the F-105D was never exported to any foreign air forces.

Specification of F-105D:

Engine: One Pratt & Whitney J75-P-19W turbojet, rated at 17,200 lb.s.t. dry and 26,500 lb.s.t. with afterburner. Performance: Maximum speed: 1420 mph at 38,000 feet, 1372 mph at 36,000 feet, 1122 mph at 50,000 feet, 836 mph at sea level. Stalling speed was 208 mph. Initial climb rate was 34,500 feet per minute (clean). Service ceiling was 32,100 feet, combat ceiling was 48,500 feet, and absolute ceiling was 50,000 feet. Combat range was 778 miles and maximum range with full external fuel was 2208 miles. Fuel: The internal weapons bay can accommodate a 390 US gallon auxiliary tank which supplements the normal internal fuel load of 1160 US gallons. This fuel load can be further augmented by a 450 or 650 US gall external tank on the fuselage centerline plus a 450 US gallon tank on each of the inboard underwing stores pylons. Dimensions: wingspan 34 feet 11 inches, length 64 feet 3 inches, height 19 feet 8 inches, wing area 385 square feet. Weights: 27,500 pounds empty, 35,637 pounds combat, 48,400 pounds gross, 52,546 pounds maximum takeoff. Armament: Armed with one 20-mm M61A1 rotary cannon with 1028 rounds. Up to 8,000 pounds of ordinance could be carried in the internal weapons bay. In addition, a further 6000 pounds of ordinance could be carried on external weapons racks (four underneath the wings, one underneath the fuselage).

Serials of F-105D:

58-1146/1148		Republic F-105D-1-RE Thunderchief
58-1149/1173		Republic F-105D-5-RE Thunderchief
58-1174/1190		Cancelled contract (believe for F-105)
59-1717/1757		Republic F-105D-5-RE Thunderchief
59-1758/1774		Republic F-105D-6-RE Thunderchief
59-1775/1816		cancelled contract for F-105D
59-1817/1826		Republic F-105D-6-RE Thunderchief
60-0409/0426		Republic F-105D-6-RE Thunderchief         
60-0427/0535		Republic F-105D-10-RE Thunderchief         
60-5374/5385		Republic F-105D-10-RE Thunderchief         
61-0041/0106		Republic F-105D-15-RE Thunderchief
61-0107/0161		Republic F-105D-20-RE Thunderchief
61-0162/0220		Republic F-105D-25-RE Thunderchief
62-4217/4237		Republic F-105D-25-RE Thunderchief
62-4238/4276		Republic F-105D-30-RE Thunderchief
62-4277/4411		Republic F-105D-31-RE Thunderchief

Sources:


  1. The Illustrated Encyclopedia of Aircraft Armament, Bill Gunston, Orion, 1988.

  2. United States Military Aircraft Since 1909, Gordon Swanborough and Peter M. Bowers, Smithsonian, 1989.

  3. The American Fighter, Enzo Angelucci and Peter Bowers, Orion, 1987.

  4. Fighters of the United States Air Force, Robert F. Dorr and David Donald, Temple Press Aerospace, 1990.

  5. American Combat Planes, Third Enlarged Edition, Ray Wagner, Doubleday, 1982.

  6. Post-World War II Fighters, 1945-1973, Marcelle Size Knaack, Office of Air Force History, 1986.

  7. The World Guide to Combat Planes, William Green, MacDonald, London, 1966

  8. The World's Fighting Planes, William Green, Doubleday, 1964.

  9. The Aircraft of the World, William Green and Gerald Pollinger, Doubleday, 1965.

  10. The Thunder Factory, Joshua Stoff, Motorbooks, 1990.

  11. F-105 Thunderchief in Detail and Scale, Bert Kinzey, Kalmbach Books, 1993.

  12. Thud, Part 1, Christian Jacquet, Air Fan International, Vol 1, No 3, March 1996

  13. Thud, Part 2, Christian Jacquet, Air Fan International, Vol 1, No 4, May 1996

  14. Warplane Classic--Republic F-105 Thunderchief, Larry Davis, International Air Power Review, Vol 6, 2002.

  15. Francesco Blasi with reference to D. Anderton ("Republic F-105 Thunderchief" - Osprey/Motorbooks Intl., 1983)

  16. E-mail from Gerald White on 507th TFG at Tinker AFB.