Here's What You Need to Remember: America’s first supersonic jet did not excel as a fighter and had beastly accident rate—but it still pioneered revolutionary new technologies and tactics, and ended up doing much of the grunt work supporting hard-pressed ground forces in the Vietnam War.

On October 14, 1947, an orange-painted Bell X-1 piloted by Chuck Yeager became the first aircraft to break the sound barrier in level flight. Though the rocket-powered X-1 was an experimental design, it followed that improving jet engine technology would make a supersonic fighter possible as well.

On its own initiative, the North American firm took a crack at evolving the F-86 Sabre, the top U.S. fighter of the Korean War, into a supersonic design. The Sabre had wings swept back 35 degrees for better high-speed performance and a large intake in its nose. The F-100 ‘Super’ Sabre’s wings were swept even further to 45 degrees, and its nose-intake distinctively tapered into a flattened elliptical shape. The first of the ‘Century Series’ of advanced 50’s-era fighters, the F-100 was nicknamed the ‘Hun’ as an abbreviation for 100.

The afterburner on the Hun’s J-57-P-7 turbojet was designed to dump raw fuel straight into the tailpipe, bypassing the jet turbine. Though this gulped fuel prodigiously, it helped boost the F-100 to supersonic speeds as high as 850 miles per hour at high altitude, allowing F-100s to set several speed records.

The Air Force finally bought into the design and introduced the F-100A model into service in October 1954. However, the Air Force’s first supersonic fighter was plagued by so many accidents, including a mid-air disintegration which killed flying ace George Welch, that the entire fleet had to be grounded. The culprit was found to be the undersized tail, which was unstable and could induce uncontrollable yaw.

Though this was corrected, the Hun had other flaws. Despite its high speed and four powerful M-39 20-millimeter cannons, it was a product of an old air warfare paradigm. It lacked air-to-air missiles and long-range search radar and relied on drop tanks to make up for a limited range. The crash-prone F-100A gradually began to be phased out in 1958.

An RF-100A high-speed reconnaissance variant, mounting four cameras and drop tanks instead of guns, was briefly more successful. Deployed to Germany and Japan, it flew high-altitude spy missions 50,000 feet over Eastern Europe, and likely China and North Korea. These ‘Slick Chicks’ were known for photographing interceptors far below ineffectually attempting to match their altitude but were superseded by even higher-flying U-2s in 1956.

The succeeding F-100C fighter-bomber (476 built) had lengthened and strengthened wings, and a more powerful J-57-P21 engine increasing top speed to 924 miles per hour and allowing it to lug 6,000 pounds of weapons on six pylons. Furthermore, it had twice the fuel capacity and a wing-mounted inflight-refueling probe. This last allowed three F-100Cs to set a single-engine distance record flying from Los Angeles to London in fourteen hours on May 13, 1957. The famous Thunderbird aerobatics team adopted F-100Cs in 1956 and used them to unleash sonic booms to amuse spectators until the FAA banned these.

The Super Sabre was again refined in the definitive F-100D model (1,274 built), which further enlarged the tail and wing, and eventually included a radar warning receiver, a seventh underbelly hardpoint, and compatibility with early AIM-9B heat-seeking air-to-air missiles. Both C and D models could carry weapons ranging from napalm canisters, Zuni 2.75-inch rockets, cluster bombs, to early AGM-45 Bullpup and AGM-83 air-to-ground guided missiles.

NATO F-100 squadrons were also readied to deploy four types of tactical nuclear bombs. But how was a fast, low-flying fighter-bomber going to escape the blast of its own nuke? This was a deadly risk even with conventional weapons, as you can see in this footage.

In fact, Hun pilots practiced a form of ‘over-the-shoulder’ toss-bombing in which the supersonic jet lunged upwards in a barrel roll. The Hun’s MA-2 Low-Altitude Bombing System automatically released the bomb as the Hun neared a vertical angle, lofting the nuke in an arc towards the target while the Super Sabre rolled over and lit the afterburners, belting in the opposite direction.

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The Air Force also tested the F-100 ZEL (Zero Length Launch), which used a colossal rocket booster slung under the rear fuselage to take off the back of a truck. The reasoning behind the bizarre truck-launched fighter was the fear that NATO airbases would be wiped out by Soviet nuclear weapons, necessitating alternative takeoff methods. Despite numerous successful tests (you can see one here), the ZEL was never deployed operationally.

Vietnam Workhorse—and First MiG Kill of the War?

In April 1961, F-100Ds in the Philippines were transferred to Thailand—the first U.S. military jets deployed to South East Asia. They did not see combat until 1964 when they were dispatched to strike anti-aircraft positions in North Vietnam. Then, beginning March 2, 1965, they began escorting faster F-105 fighter-bombers as part of the Rolling Thunder bombing campaign.

On April 4, 1965, the F-100 of Captain Donald Kilgus was covering a raid targeting the Thanh Hoa bridge when his formation was bounced by four North Vietnamese MiG-17s emerging out of cloud cover—the first jet-on-jet engagement of the Vietnam War. The MiG-17s were slower than the American supersonic jets and lacked missile armament, but their powerful triple cannons blasted one F-105 out of the sky and fatally damaged a second.

Kilgus released his drop tanks and turned sharply, managing to get on the tail of one of the MiGs. The Soviet-built fighter dove vertically towards the ground, trying to lure Kilgus into following him in a dive his heavier fighter wouldn’t be able to pull out of. Only 7,000 feet from the surface, Kilgus discharged his four cannons. According to his account:

“I saw puffs and sparks on the vertical tail of the MiG, and very shortly thereafter I didn’t see anything. I could have been at 580 knots. I won’t embroider the story by saying I got spray from the Gulf of Tonkin on my windshield, but I pulled out at the last minute.”

Of three MiGs lost that day, two were mistakenly shot down by Vietnamese flak. The unknown fate of the third may support Kilgus’s claim to have scored the first MiG kill of the war, though the Air Force listed it only as a ‘probable.’

Afterward, the dated F-100s were withdrawn from attacks on the North and reassigned to supporting ground forces battling Viet Cong in South Vietnam. In 1967, four additional Air National Guard squadrons equipped with F-100Cs were transferred. At its peak, over 490 Super Sabres were active over South Vietnam, flying an average of two ground support missions a day, either hitting pre-planned targets or responding to desperate requests for close air support.

The Air Force also converted seven two-seater F-100F trainers (out of 439 built) into the first ‘Wild Weasels’ specially modified to sniff out and whack enemy air defense radars. The EF-100F model mounted two radar receivers to track the position enemy radars, as well as rocket pods with which to mark their position for accompanying F-105s to destroy. Later, the Weasels carried AGM-145 Shrike radar-homing missiles to take out the radars themselves, destroying nine for two losses. Satisfied with the experiment, the Air Force phased in more modern F-4 and F-105s to perform the Wild Weasel mission.

The F-100F also served as “Fast Forward Air Controllers” with the back seater spotting enemies, which were then marked with smoke rockets to direct air strikes by other aircraft. Using the call-sign ‘Misty,’ Fast FACs flew over areas with a high density of air defenses too dangerous for more typical spotter planes.

The staggering tempo of Super Sabre operations amounted to 40 million pounds of bombs and napalm dropped, and more than 360,283 sorties until the F-100’s withdrawal in 1971—more than any other aircraft type, including the more famous F-4 Phantom and F-105. The F-100 pilots also paid a sobering price: over 242 F-100s were lost over Vietnam, including 186 to enemy fire and seven to airbase attacks.

However, the Super Sabre's extremely high accident rate—typically caused by compressor stalls, wing fractures, and persistent yaw instability—was even deadlier. More than 889 F-100s were lost in accidents out of 2,294 built, killing 324 pilots.

France and Denmark also operated dozens of F-105Ds and Fs, the former dispatching them on airstrikes against Algerian revolutionaries. Taiwan acquired 118 F-100A fighter variants and upgraded them with radar warning receivers and Sidewinder missiles. These reportedly sparred with Chinese Migs and flew dangerous spy missions.

Turkey received over 200s F-100Cs, Ds and Fs, which were also used to penetrate Soviet airspace, where they repeatedly dodged Su-15 interceptors, though at least one was shot down by a surface-to-air missile. Super Sabres also flew 500 sorties supporting the Turkish intervention in Cyprus between July 20-23, 1974, losing six to ground fire and two in accidents. Loaded with 750-pound bombs, Turkish F-100s blasted Nicosia Airport, provided air cover for a helicopter landing operation, and sank the Turkish destroyer Kocatep, mistaking it for a Greek warship.