The North American F-100 Super Sabre was America’s first operational supersonic fighter, but its journey from cutting-edge air-superiority aircraft to one of the most important strike fighters of the Vietnam War was anything but straightforward. Plagued by dangerous handling characteristics and early design flaws, the “Hun” evolved into a remarkably capable fighter-bomber, pioneering missions ranging from close air support to the first Wild Weasel SEADSEAD (Suppression of Enemy Air Defenses): A military operation designed to neutralize, destroy, or temporarily degrade enemy air defense systems to al... More operations and the legendary Misty Forward Air Controller program.
The Super Sabre is a legendary aircraft. Originally a basic day fighter, it would be transformed into a multi-role workhorse, flying more sorties than any other USAF fighter in the Vietnam War, from air support to SEADSEAD (Suppression of Enemy Air Defenses): A military operation designed to neutralize, destroy, or temporarily degrade enemy air defense systems to al... More and electronic warfare.
Early on, it was hoped it would be America’s next air-superiority fighter, but after entering service, it was decided that a better role for it would be air-to-ground. In fact, the F-100 would become an early strike fighter.
By the time of its active-duty retirement in 1972, it had taken a back seat to newer, more technologically advanced aircraft such as the Phantom. Yet, despite its shortcomings, the F-100 was – for most of its life – an integral component of the US Air Force.
EARLY BACKGROUND
In December 1950, the F-86 first arrived in Korea. Its combat debut against the MiG-15 marked the beginning of the jet age in air combat.
Culminating in the definitive F-86F, which arrived in 1953, the Sabre was arguably the first truly capable fighter the US Air Force had received since the P-51D. Yet despite its success, it soon became evident that the Soviets would eventually outclass it.
Years earlier, just after production of the Sabre had begun in 1949, North American AviationNorth American Aviation (NAA, United States; 1928–1967) North American Aviation was a major American aerospace manufacturer that played a central role... More had drawn up a proposal for a next-generation evolution of it, internally designated Sabre 45. In January 1951, North American then sent the proposal to the Air Force, followed by a mock-up five months later. By November, it was redesignated XF-100, and by January 3rd the next year, the Air Force had decided to order two YF-100 prototypes, followed by 23 initial production models.
PROTOTYPING AND DEVELOPMENT
The YF-100 would be a large aircraft, 14 metres long, with an 11.2-metre wingspan swept 45 degrees, four 20mm cannons, a maximum take-off weight of nearly 29000 pounds, and a single XJ57 engine producing 13200 pounds of thrust— a downrated engine compared with what would be on the production jet.
The first prototype – 52-5754 – took its maiden flight on May 25 1953, several months ahead of schedule. In an impressive performance test, even with a downrated engine, the jet reached Mach 1.05.
The second prototype – 5755 – took to the skies on October 14th for further testing.
Yet, while the initial flights proved the aircraft to be both fast and somewhat advanced for its time, issues soon became evident, which would define the early stages of its life. The new design was fast; however, it was aerodynamically dangerous.
The deadliest issue the aircraft faced was inertia coupling, a problem experienced by several other supersonic concepts of the time. From the YF-100, this issue had been noted, but the true danger wouldn’t be felt until October 12, 1954, once the F-100A had entered production.
On that day, North American’s chief test pilot, George Welch, who had tested earlier YF-100s, took the ninth production F-100A for a flight. He was to execute a planned 7.5G pull-up out of a Mach 1.5 dive to verify the airframe’s strength. Gaining speed in the dive, the aircraft suddenly departed from controlled flight before completely disintegrating.
Welch’s death was a major upset – he had been one of the two P-40 pilots who had taken off during the attack on Pearl Harbour, and throughout his career had refined his skills. Welch’s death highlighted the severe high-speed stability problems of the early Super Sabre, particularly inertia coupling and directional control limits.
Beyond this, despite retaining some shaping from the older Sabre, the F-100 wasn’t particularly agile. In a dogfight, it suffered from a long list of issues, including a small tail fin, wings and general shaping that retained energy reasonably well at speed, but at low speeds and high alpha, handling was unforgiving. Designers had placed the horizontal stabiliser low to avoid wing turbulence while pulling high AOAs, yet this didn’t resolve more serious issues. Once slow, the aircraft became sluggish and hard to control, and thanks to the 45-degree wing sweep, any high-AOA manoeuvres were extremely risky. Notably, pilots found that aileron inputs at high AOAs and lower speeds would result in adverse yaw, meaning rudder inputs had to be used instead to try to direct the nose.
At the time, this was quite troubling; Eastern Bloc fighters, namely the MiG-17 and MiG-19, were far more agile and still relatively fast, and new Soviet prototypes – like the Ye-1 and Ye-4 – were paving the way for a newer, Mach 2-capable fighter-interceptor. If forced into the merge, the F-100 was unlikely to hold any real advantage apart from raw power.
Yet the problems didn’t end there; the J-57 engines were powerful and designed for high speed. Yet they were slow to spool up, afterburners sometimes had a delay, throttle bursts could surge fuel and stall the compressor, and in a turn-fight, turbulent air through the intake could stall or even completely jam parts of the turbine.
To top it off, the F-100 quickly developed an infamous heat-related maintenance issue around the aft fuselage during prolonged afterburnerAfterburner (Reheat): An additional combustion component utilized in many supersonic military jet engines to provide a significant, temporary increase... More use.
Nevertheless, Tactical Air Command urgently needed something fast to fill the day fighter role. In 1954, the initial F-100A would enter production.
