--- title: "F-105 Thunderchief: The Thud's Fatal Flaw" description: "Ever since the first warplanes were developed, the competition for superior security in the skies above our countries has been fierce. Since the Wright Military Flyer was sold to the U.S. Air Force in 1909, research and development has been tireless in the search for the ultimate aircraft.\n\nIn 1951, a design team at Republic Aviation, an American aircraft manufacturer based in New York, began plans for a new supersonic, single-seat, tactical aircraft that they believed would be worthy of that title. Supervised by the Russian-born aircraft designer Alexander Kartveli, the plane was to be capable of carrying not only air-to-air and air-to-surface missiles, but also a single nuclear bomb.\n\nOn the surface, the project could probably not have been in better hands. Yet the aircraft that emerged — the F-105 Thunderchief — would spend nearly its entire early life fighting for its own survival, dogged by delays, cancellations, and a design built around a trade-off it could never quite escape.\n\n## A Designer With a Track Record\n\nKartveli had proven experience in plane design, having previously been involved in the production of, among others, the P-47 Thunderbolt, the F-84 Thunderjet, and the Republic F-84F Thunderstreak.\n\nThis latest project, given the name AP (Advanced Project) 63, was intended to develop a plane capable of replacing the Thunderstreak. Although there were many similarities, the newly designed F-105 Thunderchief was anticipated to be a far superior aircraft.\n\n## Building Speed Into the Airframe\n\nThe F-105 was designed as a mid-wing monoplane with a 45-degree swept wing and tail — a design borrowed from the Thunderstreak, where it had been proven to greatly increase the Mach capability of the aircraft. The F-105 also included wing-root intakes and high wing loading.\n\nDesigned to fly supersonic at very low altitude, the high wing loading gave the aircraft extra stability and less drag. However, it also made the plane less agile and created the need for longer take-off and landing distances. This was the central bargain of the airframe: raw speed and stability, bought at the cost of maneuverability.\n\nFour pylons were located on the wings — the inner set for in-flight refuelling and the outer for carrying missiles or bombs. The aircraft was not only capable of travelling many thousands of miles without landing; it could also carry an impressive 14,000 pounds of weapons, which included, as mentioned, a single nuclear bomb.\n\n## The Bomb Bay That Was Never Used\n\nIn order to safely release that bomb — safely for those on board, at least — engineers designed a hatch under the plane that slid up and into the vehicle rather than dropping underneath, greatly reducing supersonic drag. The bomb itself was lowered for deployment on a hydraulic jack to ensure accuracy and sufficient clearance from the aircraft.\n\nAlthough this was a key design feature, it was never actually used. Bombs were rarely stored in the bay, which commonly held an extra 350-gallon (1,300-litre) fuel tank instead.\n\nTop all of these specifications with an intended top speed of Mach 1.5, or 1,151 miles per hour, and on paper at least you have a fairly impressive bit of kit. It is little wonder that the first of the designs, the 105A, was approved by the Air Force in 1952.\n\n## Orders, Cancellations, and a Wavering Future\n\nAt this time, America was deeply involved in the war between North and South Korea, and the first order from the U.S. Air Force was for 199 planes. However, only two of the initial design were ever made. In 1953, the Air Force reduced the order to just 37 planes, citing — among other reasons — too many delays in development.\n\nWith the end of the war in Korea also appearing to be a distinct possibility, the whole program was cancelled by the United States Air Force towards the end of 1953, only to be reinstated in February 1955 with a firm order of 15 planes. With ongoing technological and avionic unreliability, confidence in the plane continued to waver. Despite the uncertain future of the Thunderchief and the constantly changing operational requirements, tests continued.\n\nIt would not be until 22 October 1955 that test pilot Russell \"Rusty\" Roth took to the skies in the first YF-105A. A second aircraft followed in January 1956. The prototype reached a top speed of around Mach 1.2 on its first flight.\n\n## Working Out the Problems\n\nUnfortunately, as the pilot attempted to land, the front landing wheel failed to lower, and he was forced to make an emergency landing using only the rear wheels. Although he was uninjured, the project was already drawing criticism for economic reasons and slow progress, and this landing failure did nothing to quell the diminishing support for the program.\n\nWith this at the forefront of the designers' minds, adjustments were swiftly made to the landing gear. The cause of the nose failure turned out to be a relatively simple matter — the air-intake controls were getting in the way of the descending wheel — and it was quickly rectified.\n\nAnother, more consistent problem was transonic drag. To put it simply: during flight at the speed of sound, both the aircraft and its shock waves move at the same speed. This causes a build-up, creating one large shock wave in front of the aircraft which it must then fly through. The faster the aircraft flies, the more the shock wave pushes back against it. This was addressed in new prototypes by modifying the fuselage and narrowing it towards the rear — a shape sometimes known as a \"wasp waist\" or \"slim hip.\"\n\nOne test in which the F-105 seemed to excel was the spin test. These tests are as alarming as they sound and are understandably unpopular among pilots. The test requires the pilot to deliberately lose control of the aircraft, allowing it to spin down towards the earth. Although a recovery parachute is attached to the rear of the plane, the pilot must try to regain control of the often-stalled aircraft after a certain amount of time. Thankfully, the F-105 performed well, with pilots and observers noting that it had a \"natural tendency\" to level out after rotation.\n\n## The Refuelling Headache\n\nAs research continued, an important development challenge was the ability to refuel during flight. Although this was a widely used technique on fighter jets, the size and weight of the F-105 made refuelling much more difficult. To connect to the much slower fuel tanker, the 105 had to slow down so much that its manoeuvrability was badly affected. Added to this, flying within the turbulence of the tanker led to the 105 stalling regularly.\n\nInitially, control of the refuelling was the responsibility of the pilot in the 105. Holding the plane steady amid the turbulence — and at a dangerously slow speed — he was expected to manoeuvre the plane onto the fuel hose, or drogue line, connected to the other aircraft. After many understandably unsuccessful attempts, it was decided that control should be given to an operator in the other plane, while the 105 just had to remain steady without stalling the engine.\n\nAlthough this was more efficient, many refuelling test flights and modifications to the tankers themselves were still to follow. It wasn't until jet tankers were used that mid-air refuelling of the 105 was considered a successful and reliable procedure.\n\n## From \"Thud\" to Favourite\n\nFollowing all the delays and continuously changing orders and operational requirements, in 1958 the 355th Tactical Air Squadron became the first to take delivery of the F-105B Thunderchief. With so much controversy surrounding the development and production, the reception from the Air Force was mixed. The Thunderchief had already earned the rather unfortunate nickname \"Thunder Thud,\" or \"Thud the Lead Sled,\" due to its weight and size.\n\nHowever, this reputation was about to change. When the first flights took place and the world speed record was broken, the aircraft's popularity soared. With the capacity to carry 14,000 lb of weaponry — including bombs, rockets, air-to-surface missiles, and Sidewinder missiles — coupled with the performance achieved after so much research and many adaptations, the Thuds became popular among the pilots who flew them. The nickname changed from disparaging to one of affection.\n\nDespite the initially favourable reception, in 1962 further problems led to the grounding of the whole fleet. But finally, in 1964, the F-105D model of the Thunderchief began to prove itself as the outstanding aircraft it had been expected to be.\n\n## A \"One Man Army\" Over Vietnam\n\nAmerica had become involved in the war in Vietnam in the 1960s, partly in a bid to stop the spread of communism from the north to the south, and in support of the republic in the south, which wished to remain independent. The war dragged on with no real progress, either through firepower or diplomatic relations.\n\nAt an estimated cost of $2.2 million (£1.77 million) and equipped with the larger, more powerful Pratt & Whitney J75 engine, the F-105D began service in Vietnam and soon earned the reputation of a \"One Man Army\" aircraft. The Thud was able to demonstrate its physical strength with the ability to sustain damage in battle and yet return to base to be repaired and re-flown time after time.\n\nAccording to a book by Peter E. Davies, one pilot, Murray Denton, said:\n\n> \"My first impression of the F-105 was how large and roomy the cockpit is. Coming from the F-106 Delta Dart, I couldn't believe the long take-off roll. I remember the night flights with three bags of fuel and water injection for more thrust. We would always use all the runway and milk the flaps up. The faster it flew the better it got. It operated well at sea level to 15,000 feet and in military power the jet would run faster than any other aircraft at low level — it just didn't turn much. It also had a great gun and was a very stable bomber that could take hits and come home.\"\n\n## Built to Be Maintained\n\nAt the airbases, maintenance of the planes was constant and required experienced operators to be at the end of the phone in case their expertise was needed. Regular engineers worked day and night to service, repair, and reload the aircraft.\n\nThe construction of the fuselage was such that panels could be removed to make internal repairs easy to access, while also allowing the panels themselves to be replaced if necessary. Every day, around ninety percent of the F-105Ds were ready to take off, and with all-weather navigation systems now added to the slightly longer nose of the 105D, they could fly under any conditions.\n\n## Dominance in the Skies\n\nSix hundred and ten F-105Ds were eventually deployed in Vietnam, completing an outstanding seventy-five percent of all the attack missions carried out in the first five years after their arrival. Still the reputation of the Thunderchief continued to grow. Even when coming up against the formidable Russian MiGs, their power and speed allowed them to remain dominant in the skies above Vietnam, while bringing down a reported total of 28 MiGs.\n\nAs the war continued, the flights grew longer as the Thuds made further inroads into northern Vietnam, their targets becoming more distant. Land strikes were reported to be successful, with hundreds of targets — including communication stations, bridges, and roads in North Vietnam — destroyed, despite the use of old, notoriously inaccurate iron bombs left over from the Second World War.\n\n## Pushing the Fatigue Limit\n\nWith so many flights, often at top speed and over long distances, the Thunderchief's theoretical \"fatigue lifetime\" started to become an important consideration. The expected working life of a plane of this type was 4,000 hours of flight time, and from June 1967, several of the planes had reached the halfway point.\n\nThe engines, often running at full power with the afterburners on, were the component causing the greatest concern. To alleviate some of the strain, it was decided they should be serviced every 125 hours of flight instead of the previous 200. One pilot was reported to have flown a plane that had not only sustained previous damage but had flown for 3,000 hours completing 500 missions. Until a suitable replacement was available, the Thuds would continue to fill the skies above North Vietnam, doing their job as well as they could until the end of the war.\n\n## The Cost of the Mission\n\nAs with aircraft, pilots also have a limited number of flights, and for those who flew the Thuds, the 100th and final flights often came with mixed emotions. Participating in dangerous missions at a speed of Mach 2 when at high altitude, flying the F-105D was definitely an adrenaline rush.\n\nAs much as the pilots loved the plane, the cost was steep. According to information from the Frontiers of Flight Museum in Dallas, losses were extremely high, with the chances of a Thunderchief pilot surviving their 100 missions put at only 75 percent.\n\nWhen the Vietnam War ended, the F-105Ds were no longer needed and were replaced by newer models. The remaining aircraft were passed down for training Reserves, and the last recorded flight of a Thunderchief F-105D was on 25 May 1978.\n\n## Key Takeaways\n\n- The F-105 Thunderchief began in 1951 as a Republic Aviation project under designer Alexander Kartveli, intended to replace the F-84F Thunderstreak as a supersonic, single-seat tactical aircraft capable of carrying a nuclear bomb.\n- The airframe's high wing loading and 45-degree swept wing gave it speed and stability at low altitude but sacrificed agility — the design trade-off that defined its career.\n- The program was repeatedly ordered, cut, and cancelled before being reinstated, and early prototypes wrestled with landing-gear, transonic-drag, and in-flight refuelling problems.\n- Once the F-105D matured by 1964, it became a \"One Man Army\" in Vietnam, prized for carrying 14,000 lb of ordnance and absorbing battle damage while still returning home.\n- 610 F-105Ds flew 75 percent of attack missions in their first five years in Vietnam and were credited with downing a reported 28 MiGs.\n- The cost was brutal: a pilot's chance of surviving 100 missions was put at only 75 percent, and the last recorded F-105D flight was on 25 May 1978.\n\n## Frequently Asked Questions\n\n### Who designed the F-105 Thunderchief?\n\nThe aircraft was developed by a design team at Republic Aviation in New York, supervised by the Russian-born aircraft designer Alexander Kartveli. He had previously been involved in producing the P-47 Thunderbolt, the F-84 Thunderjet, and the F-84F Thunderstreak, which the F-105 was intended to replace.\n\n### Why was the F-105 nicknamed the \"Thud\"?\n\nBecause of its considerable weight and size, the Thunderchief earned the unflattering early nicknames \"Thunder Thud\" and \"Thud the Lead Sled.\" After it broke the world speed record and proved its capability, however, the \"Thud\" nickname shifted from a put-down to a term of affection among the pilots who flew it.\n\n### What was the F-105's biggest design weakness?\n\nIts high wing loading made it fast and stable at low altitude but far less agile, and it required longer take-off and landing distances. As pilot Murray Denton put it, \"the faster it flew the better it got... it just didn't turn much.\" That lack of maneuverability was the core trade-off baked into the airframe.\n\n### How did the F-105D perform in Vietnam?\n\nThe F-105D became known as a \"One Man Army,\" able to carry heavy ordnance, take battle damage, and return to base to be repaired and flown again. 610 of them were deployed and flew 75 percent of all attack missions in their first five years there, and they were credited with shooting down a reported 28 MiGs.\n\n### Was flying the F-105 dangerous?\n\nYes. Pilots flew dangerous, long-distance missions, sometimes at Mach 2 at high altitude. According to the Frontiers of Flight Museum in Dallas, losses were extremely high — a Thunderchief pilot's chance of surviving 100 missions was put at only 75 percent.\n\n### Did the F-105 ever drop the nuclear bomb it was built around?\n\nNo. The aircraft was designed with a special internal bomb bay and a sliding hatch to carry a single nuclear bomb with minimal supersonic drag, but this feature was never actually used in that role. In practice, bombs were rarely stored in the bay, which usually held an extra 350-gallon fuel tank instead.\n\n## Sources\n\n- [Original MegaProjects video: The F-105 Thunderchief: The Supersonic Bomber's Fatal Flaw](https://www.youtube.com/watch?v=5Tah4qWOuwk)\n- [Republic F-105 Thunderchief — Wikipedia](https://en.wikipedia.org/wiki/Republic_F-105_Thunderchief)\n- [Republic F-105D Thunderchief — National Museum of the United States Air Force](https://www.nationalmuseum.af.mil/Visit/Museum-Exhibits/Fact-Sheets/Display/Article/196054/republic-f-105d-thunderchief/)\n- [F-105 Thunderchief MiG Killers of the Vietnam War by Peter E. Davies — Osprey Publishing](https://www.ospreypublishing.com/us/f105-thunderchief-mig-killers-of-the-vietnam-war-9781782008040/)\n\n- [Hero image source](https://commons.wikimedia.org/wiki/File:Republic_F-105D-30-RE_(SN_62-4234)_in_flight_with_full_bomb_load_060901-F-1234S-013.jpg) by U.S. Air Force / Wikimedia Commons, public domain.\n\n## Related Coverage\n\n- [Boeing E-4: America's Advanced Airborne Command Post](/article/boeing-e-4-americas-advanced-airborne-command-post)\n\n- [The Changhe Z-10: China's Twin-Turbo Answer to the Apache](/article/changhe-z-10-china-attack-helicopter)\n\n- [The Convair B-36 Peacemaker: The Absolute Unit That Carried America Into the Cold War](/article/convair-b-36-peacemaker-cold-war-bomber)" url: https://megaprojects.pub/article/f-105-thunderchief-supersonic-bomber-fatal-flaw.md canonical: https://megaprojects.pub/article/f-105-thunderchief-supersonic-bomber-fatal-flaw datePublished: 2026-06-09 dateModified: 2026-06-09 author: - name: Simon Whistler url: https://megaprojects.pub/author/simon-whistler publisher: MegaProjects image: "https://media.megaprojects.pub/cdn-cgi/image/width=600,height=338,fit=cover,quality=80,format=auto/articles/5Tah4qWOuwk/hero.jpg" type: NewsArticle contentHash: 02861120c4e7a723a791e67e69373b65cbd8c628943b30794ddfb96efa4531cd tokens: 4400 summaryUrl: https://megaprojects.pub/article/f-105-thunderchief-supersonic-bomber-fatal-flaw.md.summary.md --- Ever since the first warplanes were developed, the competition for superior security in the skies above our countries has been fierce. Since the Wright Military Flyer was sold to the U.S. Air Force in 1909, research and development has been tireless in the search for the ultimate aircraft. In 1951, a design team at Republic Aviation, an American aircraft manufacturer based in New York, began plans for a new supersonic, single-seat, tactical aircraft that they believed would be worthy of that title. Supervised by the Russian-born aircraft designer Alexander Kartveli, the plane was to be capable of carrying not only air-to-air and air-to-surface missiles, but also a single nuclear bomb. On the surface, the project could probably not have been in better hands. Yet the aircraft that emerged — the F-105 Thunderchief — would spend nearly its entire early life fighting for its own survival, dogged by delays, cancellations, and a design built around a trade-off it could never quite escape. ## A Designer With a Track Record Kartveli had proven experience in plane design, having previously been involved in the production of, among others, the P-47 Thunderbolt, the F-84 Thunderjet, and the Republic F-84F Thunderstreak. This latest project, given the name AP (Advanced Project) 63, was intended to develop a plane capable of replacing the Thunderstreak. Although there were many similarities, the newly designed F-105 Thunderchief was anticipated to be a far superior aircraft. ## Building Speed Into the Airframe The F-105 was designed as a mid-wing monoplane with a 45-degree swept wing and tail — a design borrowed from the Thunderstreak, where it had been proven to greatly increase the Mach capability of the aircraft. The F-105 also included wing-root intakes and high wing loading. Designed to fly supersonic at very low altitude, the high wing loading gave the aircraft extra stability and less drag. However, it also made the plane less agile and created the need for longer take-off and landing distances. This was the central bargain of the airframe: raw speed and stability, bought at the cost of maneuverability. Four pylons were located on the wings — the inner set for in-flight refuelling and the outer for carrying missiles or bombs. The aircraft was not only capable of travelling many thousands of miles without landing; it could also carry an impressive 14,000 pounds of weapons, which included, as mentioned, a single nuclear bomb. ## The Bomb Bay That Was Never Used In order to safely release that bomb — safely for those on board, at least — engineers designed a hatch under the plane that slid up and into the vehicle rather than dropping underneath, greatly reducing supersonic drag. The bomb itself was lowered for deployment on a hydraulic jack to ensure accuracy and sufficient clearance from the aircraft. Although this was a key design feature, it was never actually used. Bombs were rarely stored in the bay, which commonly held an extra 350-gallon (1,300-litre) fuel tank instead. Top all of these specifications with an intended top speed of Mach 1.5, or 1,151 miles per hour, and on paper at least you have a fairly impressive bit of kit. It is little wonder that the first of the designs, the 105A, was approved by the Air Force in 1952. ## Orders, Cancellations, and a Wavering Future At this time, America was deeply involved in the war between North and South Korea, and the first order from the U.S. Air Force was for 199 planes. However, only two of the initial design were ever made. In 1953, the Air Force reduced the order to just 37 planes, citing — among other reasons — too many delays in development. With the end of the war in Korea also appearing to be a distinct possibility, the whole program was cancelled by the United States Air Force towards the end of 1953, only to be reinstated in February 1955 with a firm order of 15 planes. With ongoing technological and avionic unreliability, confidence in the plane continued to waver. Despite the uncertain future of the Thunderchief and the constantly changing operational requirements, tests continued. It would not be until 22 October 1955 that test pilot Russell "Rusty" Roth took to the skies in the first YF-105A. A second aircraft followed in January 1956. The prototype reached a top speed of around Mach 1.2 on its first flight. ## Working Out the Problems Unfortunately, as the pilot attempted to land, the front landing wheel failed to lower, and he was forced to make an emergency landing using only the rear wheels. Although he was uninjured, the project was already drawing criticism for economic reasons and slow progress, and this landing failure did nothing to quell the diminishing support for the program. With this at the forefront of the designers' minds, adjustments were swiftly made to the landing gear. The cause of the nose failure turned out to be a relatively simple matter — the air-intake controls were getting in the way of the descending wheel — and it was quickly rectified. Another, more consistent problem was transonic drag. To put it simply: during flight at the speed of sound, both the aircraft and its shock waves move at the same speed. This causes a build-up, creating one large shock wave in front of the aircraft which it must then fly through. The faster the aircraft flies, the more the shock wave pushes back against it. This was addressed in new prototypes by modifying the fuselage and narrowing it towards the rear — a shape sometimes known as a "wasp waist" or "slim hip." One test in which the F-105 seemed to excel was the spin test. These tests are as alarming as they sound and are understandably unpopular among pilots. The test requires the pilot to deliberately lose control of the aircraft, allowing it to spin down towards the earth. Although a recovery parachute is attached to the rear of the plane, the pilot must try to regain control of the often-stalled aircraft after a certain amount of time. Thankfully, the F-105 performed well, with pilots and observers noting that it had a "natural tendency" to level out after rotation. ## The Refuelling Headache As research continued, an important development challenge was the ability to refuel during flight. Although this was a widely used technique on fighter jets, the size and weight of the F-105 made refuelling much more difficult. To connect to the much slower fuel tanker, the 105 had to slow down so much that its manoeuvrability was badly affected. Added to this, flying within the turbulence of the tanker led to the 105 stalling regularly. Initially, control of the refuelling was the responsibility of the pilot in the 105. Holding the plane steady amid the turbulence — and at a dangerously slow speed — he was expected to manoeuvre the plane onto the fuel hose, or drogue line, connected to the other aircraft. After many understandably unsuccessful attempts, it was decided that control should be given to an operator in the other plane, while the 105 just had to remain steady without stalling the engine. Although this was more efficient, many refuelling test flights and modifications to the tankers themselves were still to follow. It wasn't until jet tankers were used that mid-air refuelling of the 105 was considered a successful and reliable procedure. ## From "Thud" to Favourite Following all the delays and continuously changing orders and operational requirements, in 1958 the 355th Tactical Air Squadron became the first to take delivery of the F-105B Thunderchief. With so much controversy surrounding the development and production, the reception from the Air Force was mixed. The Thunderchief had already earned the rather unfortunate nickname "Thunder Thud," or "Thud the Lead Sled," due to its weight and size. However, this reputation was about to change. When the first flights took place and the world speed record was broken, the aircraft's popularity soared. With the capacity to carry 14,000 lb of weaponry — including bombs, rockets, air-to-surface missiles, and Sidewinder missiles — coupled with the performance achieved after so much research and many adaptations, the Thuds became popular among the pilots who flew them. The nickname changed from disparaging to one of affection. Despite the initially favourable reception, in 1962 further problems led to the grounding of the whole fleet. But finally, in 1964, the F-105D model of the Thunderchief began to prove itself as the outstanding aircraft it had been expected to be. ## A "One Man Army" Over Vietnam America had become involved in the war in Vietnam in the 1960s, partly in a bid to stop the spread of communism from the north to the south, and in support of the republic in the south, which wished to remain independent. The war dragged on with no real progress, either through firepower or diplomatic relations. At an estimated cost of $2.2 million (£1.77 million) and equipped with the larger, more powerful Pratt & Whitney J75 engine, the F-105D began service in Vietnam and soon earned the reputation of a "One Man Army" aircraft. The Thud was able to demonstrate its physical strength with the ability to sustain damage in battle and yet return to base to be repaired and re-flown time after time. According to a book by Peter E. Davies, one pilot, Murray Denton, said: > "My first impression of the F-105 was how large and roomy the cockpit is. Coming from the F-106 Delta Dart, I couldn't believe the long take-off roll. I remember the night flights with three bags of fuel and water injection for more thrust. We would always use all the runway and milk the flaps up. The faster it flew the better it got. It operated well at sea level to 15,000 feet and in military power the jet would run faster than any other aircraft at low level — it just didn't turn much. It also had a great gun and was a very stable bomber that could take hits and come home." ## Built to Be Maintained At the airbases, maintenance of the planes was constant and required experienced operators to be at the end of the phone in case their expertise was needed. Regular engineers worked day and night to service, repair, and reload the aircraft. The construction of the fuselage was such that panels could be removed to make internal repairs easy to access, while also allowing the panels themselves to be replaced if necessary. Every day, around ninety percent of the F-105Ds were ready to take off, and with all-weather navigation systems now added to the slightly longer nose of the 105D, they could fly under any conditions. ## Dominance in the Skies Six hundred and ten F-105Ds were eventually deployed in Vietnam, completing an outstanding seventy-five percent of all the attack missions carried out in the first five years after their arrival. Still the reputation of the Thunderchief continued to grow. Even when coming up against the formidable Russian MiGs, their power and speed allowed them to remain dominant in the skies above Vietnam, while bringing down a reported total of 28 MiGs. As the war continued, the flights grew longer as the Thuds made further inroads into northern Vietnam, their targets becoming more distant. Land strikes were reported to be successful, with hundreds of targets — including communication stations, bridges, and roads in North Vietnam — destroyed, despite the use of old, notoriously inaccurate iron bombs left over from the Second World War. ## Pushing the Fatigue Limit With so many flights, often at top speed and over long distances, the Thunderchief's theoretical "fatigue lifetime" started to become an important consideration. The expected working life of a plane of this type was 4,000 hours of flight time, and from June 1967, several of the planes had reached the halfway point. The engines, often running at full power with the afterburners on, were the component causing the greatest concern. To alleviate some of the strain, it was decided they should be serviced every 125 hours of flight instead of the previous 200. One pilot was reported to have flown a plane that had not only sustained previous damage but had flown for 3,000 hours completing 500 missions. Until a suitable replacement was available, the Thuds would continue to fill the skies above North Vietnam, doing their job as well as they could until the end of the war. ## The Cost of the Mission As with aircraft, pilots also have a limited number of flights, and for those who flew the Thuds, the 100th and final flights often came with mixed emotions. Participating in dangerous missions at a speed of Mach 2 when at high altitude, flying the F-105D was definitely an adrenaline rush. As much as the pilots loved the plane, the cost was steep. According to information from the Frontiers of Flight Museum in Dallas, losses were extremely high, with the chances of a Thunderchief pilot surviving their 100 missions put at only 75 percent. When the Vietnam War ended, the F-105Ds were no longer needed and were replaced by newer models. The remaining aircraft were passed down for training Reserves, and the last recorded flight of a Thunderchief F-105D was on 25 May 1978. ## Key Takeaways - The F-105 Thunderchief began in 1951 as a Republic Aviation project under designer Alexander Kartveli, intended to replace the F-84F Thunderstreak as a supersonic, single-seat tactical aircraft capable of carrying a nuclear bomb. - The airframe's high wing loading and 45-degree swept wing gave it speed and stability at low altitude but sacrificed agility — the design trade-off that defined its career. - The program was repeatedly ordered, cut, and cancelled before being reinstated, and early prototypes wrestled with landing-gear, transonic-drag, and in-flight refuelling problems. - Once the F-105D matured by 1964, it became a "One Man Army" in Vietnam, prized for carrying 14,000 lb of ordnance and absorbing battle damage while still returning home. - 610 F-105Ds flew 75 percent of attack missions in their first five years in Vietnam and were credited with downing a reported 28 MiGs. - The cost was brutal: a pilot's chance of surviving 100 missions was put at only 75 percent, and the last recorded F-105D flight was on 25 May 1978. ## Frequently Asked Questions ### Who designed the F-105 Thunderchief? The aircraft was developed by a design team at Republic Aviation in New York, supervised by the Russian-born aircraft designer Alexander Kartveli. He had previously been involved in producing the P-47 Thunderbolt, the F-84 Thunderjet, and the F-84F Thunderstreak, which the F-105 was intended to replace. ### Why was the F-105 nicknamed the "Thud"? Because of its considerable weight and size, the Thunderchief earned the unflattering early nicknames "Thunder Thud" and "Thud the Lead Sled." After it broke the world speed record and proved its capability, however, the "Thud" nickname shifted from a put-down to a term of affection among the pilots who flew it. ### What was the F-105's biggest design weakness? Its high wing loading made it fast and stable at low altitude but far less agile, and it required longer take-off and landing distances. As pilot Murray Denton put it, "the faster it flew the better it got... it just didn't turn much." That lack of maneuverability was the core trade-off baked into the airframe. ### How did the F-105D perform in Vietnam? The F-105D became known as a "One Man Army," able to carry heavy ordnance, take battle damage, and return to base to be repaired and flown again. 610 of them were deployed and flew 75 percent of all attack missions in their first five years there, and they were credited with shooting down a reported 28 MiGs. ### Was flying the F-105 dangerous? Yes. Pilots flew dangerous, long-distance missions, sometimes at Mach 2 at high altitude. According to the Frontiers of Flight Museum in Dallas, losses were extremely high — a Thunderchief pilot's chance of surviving 100 missions was put at only 75 percent. ### Did the F-105 ever drop the nuclear bomb it was built around? No. The aircraft was designed with a special internal bomb bay and a sliding hatch to carry a single nuclear bomb with minimal supersonic drag, but this feature was never actually used in that role. In practice, bombs were rarely stored in the bay, which usually held an extra 350-gallon fuel tank instead. ## Sources - [Original MegaProjects video: The F-105 Thunderchief: The Supersonic Bomber's Fatal Flaw](https://www.youtube.com/watch?v=5Tah4qWOuwk) - [Republic F-105 Thunderchief — Wikipedia](https://en.wikipedia.org/wiki/Republic_F-105_Thunderchief) - [Republic F-105D Thunderchief — National Museum of the United States Air Force](https://www.nationalmuseum.af.mil/Visit/Museum-Exhibits/Fact-Sheets/Display/Article/196054/republic-f-105d-thunderchief/) - [F-105 Thunderchief MiG Killers of the Vietnam War by Peter E. Davies — Osprey Publishing](https://www.ospreypublishing.com/us/f105-thunderchief-mig-killers-of-the-vietnam-war-9781782008040/) - [Hero image source](https://commons.wikimedia.org/wiki/File:Republic_F-105D-30-RE_(SN_62-4234)_in_flight_with_full_bomb_load_060901-F-1234S-013.jpg) by U.S. Air Force / Wikimedia Commons, public domain. ## Related Coverage - [Boeing E-4: America's Advanced Airborne Command Post](/article/boeing-e-4-americas-advanced-airborne-command-post) - [The Changhe Z-10: China's Twin-Turbo Answer to the Apache](/article/changhe-z-10-china-attack-helicopter) - [The Convair B-36 Peacemaker: The Absolute Unit That Carried America Into the Cold War](/article/convair-b-36-peacemaker-cold-war-bomber)