North American F-100 Super Sabre Single-Seat Fighter-Bomber / Air Superiority / Tactical Reconnaissance Aircraft
Though not without issues early on, the North American F-100 Super Sabre jet evolved into one of the finest American fighter aircraft.
Authored By Staff Writer; Content ©www.MilitaryFactory.com
The North American F-100 Super Sabre was developed as the successor to the F-86 Sabre, another North American product. The F-86 Sabre proved a war winner for the Americans in the Korean War, tangling with the likes of the new Soviet jet-powered fighter - the Mikoyan-Gurevich MiG-15 "Fagot" - in much the same way that the North American P-51 Mustang succeeded against German and Japanese foes before it in World War 2. By this time, North American Aviation had built up an impressive history by supplying these successful designs in changing times. The F-100 Super Sabre was no different - it was an in-house development that was presented to the USAF and ultimately accepted into service. The aircraft came about at a time when aviation engineers were convinced that Mach 1+ sustained flight was capable - with the sound barrier being broken just years before by military aviator Chuck Yeager in his Bell XS-1 - now the challenge lay in ironing out a Mach 1-capable design to be mated with a consistently performing and powerful turbojet engine. Likewise, the Soviet Union and her Mikoyan-Gurevich bureau was also hard at work, beginning development of what would eventually become the MiG-19 "Farmer" - effectively the F-100 Super Sabre's contemporary - though the two aircraft never saw combat against one another.
The F-100 was affectionately known as the "Hun", no doubt due to its "F-100" (one-HUN-dred) designation.
In early 1949, North American Aviation was exploring ideas for Mach 1 sustained flight as an in-house development. The success of the F-86 Sabre lay in several sources, in particular were the captured aerodynamic documents from Germany following World War 2 and advanced testing being done through the National Advisory Committee on Aeronautics (NACA). These, coupled with true aviation engineering began to push the threshold of military aviation design to an all new limit. The changing times and advancing technology present following World War 2 and into the 1950's made achieving Mach 1 sustained flight all the more reachable.
North American looked to the successes inherent in their F-86 Sabre design to try and produce a worthy successor consistent with the evolving battlefield. The 35-degree wing sweep of the Sabre was developed into a greater 45-degree angle coupled with a modified fuselage. This design route produced a slightly better fighter concept but a ceiling was inevitably reached that required the use of a capable powerplant to break the airframe out and over the Mach 1 threshold on a consistent basis. After several turbojet developments were entertained, a General Electric brand J47 with afterburning was selected and coupled with the F-86D "Dog Sabre" - the all-weather version of the successful Korean War jet fighter with the identifiable "snout" nose assembly. This design was showcased for the USAF and rejected. A modified F-86E followed only to be rejected once more. A third design was submitted for review - this being a combination of the first and second design submittals - and was finally accepted for further development.
The aircraft became known as "Sabre 45", denoting its 45-degree wing angle sweep and its F-86 Sabre origins. A Pratt & Whitney J57 series was selected as the new powerplant and was itself to become as legendary as the Sabre series. The J57-P-7, as thirsty as it was, still provided the best bang and performance for the new fighter considering all the other frontrunners at the time. North American Aviation submitted a proposal for two prototype models to be constructed based on the Sabre 45 design study and the USAF granted the contract along with provisions for a possible 94 Sabre 45 production models in the future. The USAF officially christened the new design as the F-100A series on December 7th, 1951.
Many challenges lay ahead for the design group and no stone was left unturned. To achieve consistent Mach 1 flight would require a completely new airframe approach. As such, the 45-degree wing sweep was coupled with a thinner overall air foil when compared to that on the F-86 Sabre production models. Of particular note for the wings was also the design decision to place the ailerons inboard as opposed to outboard. In effect, this provided the new aircraft with exceptional rolling capabilities in high-speed flight but also curtailed wing twisting and bending. The wings were also kept low on the fuselage with the stabilizers behind it kept lower on the empennage - below the wing chord plane essentially. These stabilizers were known as "all-flying" surfaces for they moved as complete pieces in unison with one another. The system was constructed as separate components but held together by a single tubular fastener, allowing for the system to move as one entire unit. This was important in that the stabilizers were charged with dealing with any airflow "downwash" emanating along the wing trailing edges. This had a propensity to force the aircraft to nose up. The F-100 would become the first aircraft to incorporate this feature into its design. The empennage was dominated by a conventional vertical tail fin that sported the rudder.
The forward-mounted air intake duct opening was fitted into an extended nose assembly with the intake opening now more of an oval with a thinner lip than that as found on the original Sabre. This allowed for a good amount of air to be forced inwards toward the turbojet engine. By comparison, the new design was a full quarter longer than the original Sabre, with ductwork running about the first half of the fuselage and the engine taking up the second half. Because of the nature of the materials needed, even the manufacturing facilities would need special attention to keep the construction of the aircraft as consistent as possible across all production models leaving factories.
The fuselage was properly contoured with the cockpit sitting forward of the design under a clamshell canopy. Construction of the fuselage was of a semi-monocoque design with stressed skin. The pilot sat in a climate-controlled and pressurized tub with windshield defrosters to combat high-altitude/high-speed icing. Probably the most important element of his position was his ejection seat - this coming in two flavors. The first type was a simple ejection seat process that initiated jettisoning - first the canopy and then the seat with the pilot via cartridges. The second type featured a 7,500lb thrust rocket and cartridge system which jettisoned the canopy first, followed by the pilot in his powered chair, blown clear of the aircraft. The rocket-powered escape method allowed for improved low-altitude escapes though both methods provided the pilot to benefit of safe ejection at any speed and at any altitude.
The aircraft began life as two produced prototypes under the designation of YF-100A. The first was completed on April 24th, 1953 and had its first flight on May 25th of that year, breaking the speed of sound. The second YF-100 prototype followed in July.
Testing with these YF-100A "Super Sabres" ensued and feedback unveiled deficiencies in visibility over the nose during take-off and landing and poor handling at low speeds. Level flight at high speeds was also noted for its lack of stability while the fighter as a gun platform in whole was put into question. Pilots also noted the rather smallish size of the vertical stabilizer. Despite these shortcomings as reported by USAF test pilots, both the USAF and North American Aviation wanted the Super Sabre program progressed as swiftly as possible. This decision would have disastrous consequences for the Super Sabre project.
On October 12th, 1954, an F-100A was finally pushed to the limit. During an exercise testing the physical limits of the Super Sabre air frame in a Mach-speed dive, the aircraft disintegrated in an explosion. The North American Aviation pilot, George Welch, eventually succumbed to his wounds and died a short time later. Post-accident review unveiled an all-new violent aerodynamic phenomenon known as "inertia roll coupling" brought about by tail flutter - not an unseen or unknown issue among aviation engineers but a mountain that would have to be climbed when mankind would inevitably reach it. What this exercise prominently revealed was an inherent design flaw, centering in on the vertical stabilizer itself. The violent reaction of the Super Sabre to inertia roll coupling forced timely reviews of the occurrence. As a result vertical tail surfaces were increased to counteract the effect.
The first F-100A production model rolled off the assembly lines on September 25th, 1953, eventually accepted by Tactical Air Command (TAC) nearly a year later on September 18th, 1954. The F-100A was a single-seat, daytime, air superiority fighter. The F-100A model was intended to be highly based on the YF-100A prototypes but changes induced by North American Aviation engineers produced a sub-par air superiority performer in the finished A-model product. In essence, the performance of the system was definitely there but the aircraft lacked in other vital areas to make it a true dedicated contender for the USAF. In that respect, the F-100A was something of a disappointment with production encompassing just 203 examples. The A-models were being phased out of USAF service by the late 1950's.
Despite their relative ineffectiveness, an F-100A model was credited with setting a new speed record of 755 miles per hour on October 29th, 1953.
The F-100B (F-107A "Ultra Sabre") bears some mention here. Thought it does not represent a true production variant of the Super Sabre family, it showcases the Super Sabre as a promising and highly evolved platform, meant to compete directly with the Republic F-105 Thunderchief. The F-100B was brought about out of necessity for North American Aviation to shore up the shortcomings of its F-100A production models. In its initial form, the F-100B externally reflected the F-100A in many ways including use of the same wings and nose-mounted air intake. As the project specs evolved, so too did the outward design. The new aircraft sported a sleeker and more pointed fuselage with a nose radome, redesigned cockpit with new features, a revised canopy to improve pilot visibility and a repositioning of the nose-mounted intake duct to the dorsal part of the fuselage - with the opening above and aft of the pilots position. Production was expected to begin in 1955 with power supplied from an updated form of the Pratt & Whitney J57 engine designated as the J57-P-11. The aircraft featured an impressive fuel load with strengthened landing gear struts to allow for operations from rough fields and ordnance-carrying capability. Construction was monocoque all-metal with stressed skin. The wings were slightly redesigned from the original F-100B example. The North American YF-107 was to face off against the F-105 in tests but these never materialized with the USAF surprisingly giving the go-ahead to the Republic design. The YF-107 therefore fell out of the picture altogether and was relegated as a test platform for the NACA. Just three YF-107's were eventually completed.
The USAF modified their contract with North American Aviation to produce the remaining 70 A-models to a newer C-model standard, this effectively a fighter-bomber variant with nuclear missile capability. The C-model also featured lengthened wings to help improve rolling but beyond this external change, it was effectively similar to the A-models. The new wings were also strengthened to allow for the carrying of external munitions with six hardpoints available. Additionally, C-models were the first to feature in-flight refueling via a probe extending outwards from under the starboard wing component. Along with the refueling element, the wings of the F-100C were fitted with fuel cells noted by the term "wet wing", a design element specifically requested by the USAF to help increase the limited range of the F-100A models. This improved the operational capabilities of the F-100C without reliance on externally held fuel tanks. The C-model was a "step up" in most respects, incorporating the ground attack feature to make it a true fighter-bomber - in effect, a multi-role performer to an extent. Armament could now go beyond the standard cannon armament and a few bombs - nuclear munitions and High Velocity Aircraft Rockets (HVAR) could now be carried in addition to external fuel tanks if needed. The AGM-12 Bullpup air-to-ground missile was added to the mix. A 335-gallon fuel tank was introduced. The Pratt & Whitney J57-P-7 was also improved with more power output.
The F-100D became the definitive Super Sabre, produced in no fewer than 1,274 examples. Instead of it being a conversion fighter-bomber model, the D-model was designed from the outset as a dedicated fighter-bomber platform. Key features included in-flight refueling, ECM (Electronic Counter Measures) equipment, larger wing and tail surfaces, an autopilot system and a "buddy" refueling system - allowing one F-100 to refuel another. Additional flaps became standard in this model to accommodate for the longer landing distances inherent in this heavier aircraft. A 450-gallon external fuel tank option was also introduced. Like the C-model before it, the D-model could sport the AGM-12 Bullpup air-to-surface missile.
The F-100F followed the D-model. This particular model was introduced as a two-seat trainer in the hopes of curtailing the appalling accident rates encountered with the F-100. As a pioneer of Mach 1 flight, it was without question that the aircraft would see a few bumps in the road. The F-100F was developed from a single-seat F-100C model known as the TF-100C and 339 F-models were delivered to the USAF. The prototype trainer first flew in July of 1957. Unfortunately, the trainer did little in the way to bring the accident numbers down to acceptable status. These F-100F models took on the designation of TF-100. The F-100 would, however, find itself a home in the "Wild Weasel" role - and anti-radar version of the Super Sabre that utilized the two-pilot configuration to good effect. Despite its origins in the C-model, the F-model was more akin to the D-model, retaining its new wing design and, thus, its external munitions capability. USAF F-100F "Wild Weasels" proved effective in the Vietnam War and were distinguished from their two-seat trainers by the appearance of angled antennas protruding from the underside of the nose intake and the trailing edge of the vertical tail fin.
The QF-100 was the designation used for target drones represented by the F-100 series. As can be assumed, distinct designations per model type are noted as such - the QF-100D represents the F-100D in target drone form, etc...
The RF-100A "Slick Chick" represented six F-100A conversion models in tactical reconnaissance forms. These aircraft saw their M39 cannon systems and ammunition stores removed in favor of five reconnaissance scanning cameras. Additionally, the aircraft was fitted with up to four external fuel tanks to get the most out of their operational range.
As standard, all combat Super Sabres carried a battery of 4 x Pontiac M39E automatic cannons. These cannons were based upon the World War 2-era German Mauser MG213C 30mm cannon but with a higher rate-of-fire in a 20mm form, with projectiles fed from a revolving gas-operated cylinder type arrangement. The cannons were allocated to a position underneath the cockpit and intake duct work. The weapons were in a staggered formation, two to a side. Spent ammunition casings were forcibly ejected away from the aircraft to reduce any damage to the underside. Between 200 and 275 rounds of ammunition could be carried as needed. Aiming was assisted by the A4 gyro-computing gun sight in the cockpit.
Weapons varied slightly from model to model. The C-model, as noted above, introduced true fighter-bomber characteristics, especially with their new six-hardpoint wings. Despite slight differences between models, all F-100 Super Sabres were cleared to use two missile types - the AIM-9B Sidewinder short-range, air-to-air missile and the AGM-12B Bullpup, an air-to-surface missile. Later Wild Weasel derivatives were sporting the AGM-45 Shrike anti-radiation/anti-radar missile systems. F-100's could also carry conventional bomb loadouts of varying weights as well as high velocity 5" rockets. Bomb and rocket aiming was handled by the A4 gun sight as well.
Perhaps most important to the Super Sabre - considering its introduction into a Cold War-dominated world - was the ability for the aircraft to carry and release nuclear-tipped missiles. Types cleared for use included the B28, B43, B57, B61 an MK7 munitions.
Both the D- and F-models made use of the Low-Altitude Bombing System (LABS). In essence, this allowed the Super Sabre to "toss" ordnance onto a target. The F-100 could fly at speed above the trees and then immediately pull up to release its ordnance. While the aircraft continued on its way, the falling ordnance would follow its gravitational path, or trajectory, towards the target.
Some F-100 Super Sabres were showcased in a "ZEL" (Zero-Length Launch System) program testing the aircraft out with rocket-assisted take-offs. These aircraft would have been stationed throughout NATO countries across Europe and be a first-response element against the impending Soviet invasion. As airborne Soviet nuclear missiles represented NATO air forces with a limited window to which launch their aircraft, the program was deemed a requirement though it never fully materialized for one reason or another.
Besides service with the USAF, the Super Sabre became a relative favorite amongst its NATO partners and general American allies. Operators included Denmark, France, Turkey and Taiwan. A total of 2,294 F-100 Super Sabres were produced including the two YF-100A prototypes. Models encompassed just the A-, C-, D- and F-model series but on the whole, they were largely similar to one another. Production of all F-100 Super Sabres completed in 1959.
Perhaps the biggest operational use of the F-100 Super Sabre was in their F-100F "Wild Weasel" forms throughout the Vietnam War, their use spanning from 1966 into 1971. Wild Weasel is a generic term still in use today that associated any combat aircraft with their dedicated radar-destruction role. As such, you can have the F-4 Phantom in the Wild Weasel role just as the F-100 Super Sabre was featured in this fashion in Southeast Asia. Beyond their anti-radar roles, Super Sabres also filled in the air superiority, fighter-bomber and reconnaissance roles as needed. In all, the Super Sabre concluded more sorties in the conflict than the P-51 Mustang did in all of World War 2.
Soviet-produced SAM (Surface-to-Air-Missile) elements dotted North Vietnam and proved a hazard for all American airmen in service. The F-100F Wild Weasel was a converted form of the two-seat F-100F trainer where the two-person cockpit played well into Wild Weasel functions that required the use of a pilot and radar systems operator. In addition to SAMs, American airmen had to contend with AAA (Anti-Aircraft Artillery) and on-call interceptors in the form of MiG-17 "Farmers" and MiG-21 "Fishbeds".
Specialized equipment was added to these F-100Fs with no issue and actual function was markedly impressive. The rear-seat operator would pinpoint the given radar signal and ride it back to its point of origin. The pilot could then "mark" the area via rockets for the incoming group of fighter-bombers to target. With the development of the AGM-45 Shrike anti-radar missile, the role of Wild Weasel effectively transferred to the Republic F-105 Thunderchiefs and the McDonnell F-4 Phantoms. F-100 Super Sabres lived out their days in the Vietnam conflict as FAC (Forward-Air-Control) aircraft singularly dubbed as "Misty".
Super Sabres also served with the United States Air Force demonstration team "Thunderbirds" who continually upgraded their F-100 models as newer forms became available. A notable aircraft loss occurred in 1967 to which the airborne Super Sabre's wings collapsed onto the fuselage, spilling and igniting fuel. Though the pilot amazingly ejected to safety, the incident caused some concern from the USAF and North American Aviation, to which some modifications were put forth during production of the F-100D series.
As previously mentioned, F-100 Super Sabres were showcased throughout NATO countries, meaning that many were stationed throughout Europe to combat any Soviet aggression. The USAF discontinued use of the F-100 in 1972. Air National Guard units continued use of the type up until 1980 while at least one foreign operator was still fielding the aircraft operationally as recently as 1985 - a true testament to the aircrafts design.
The F-100 Super Sabre was indeed a true American fighter joining the likes of the P-51 Mustang and F-86 Sabre before it - all noted North American Aviation designs. It was a ground breaking design that set records at a time when technology was effectively forcing the push of the speed envelope. The aircraft became the world's first such system to reach Mach 1 in level flight and achieve it on a consistent basis, beating the Soviet MiG-19 to the punch by several months. The F-100 was not without its shortcomings and the fact that lives were lost to it in development showcased the infancy of understanding the limits to speed in flight. In the end, the F-100 Super Sabre proved her worth - with all the manpower, hours and dollars poured into the design - becoming a highly identifiable and respected aircraft and quite possibly the pinnacle of fighter design at North American Aviation.