Chuck Yeager and the X-1
Yeager with the X-1. Its name, Glamorous Glennis, was for his wife. National Air and Space Museum

On October 14, 1947, a B-29 bomber dropped Chuck Yeager and his ride—the X-1—out of its bay and into the sky at 20,000 feet. This excursion, his ninth powered flight in the plane, would mark the moment that wrote the test pilot into the history books as the first person to break the sound barrier. Shepherded upwards in that bomber, Yeager’s craft had saved the precious rocket fuel it needed to reach 700 mph.

“I noticed that the faster I got, the smoother the ride,” he recounted in his 1985 book, Yeager: An Autobiography. “Suddenly the Mach needle began to fluctuate,” he continued. “It went up to 0.965 Mach—then tipped right off the scale. I thought I was seeing things! We were flying supersonic!” He landed safely, noting that more “white-knuckle flights” in that aircraft were to come. “The real hero in the flight test business is a pilot who manages to survive,” he reflected.

Survive he did. Yeager, who was born in 1923 in West Virginia, died yesterday at the age of 97 after a long career as an aviator in which he flew next-generation jets and trained astronauts. When he was 18, he joined the Army Air Corps, and while working as an airplane mechanic he took his first flight, as a passenger. “I threw up all over the back seat,” he wrote. Undeterred by the airsickness, he eventually began training as a pilot. In World War II he flew P-51 fighters in more than 60 combat missions, and joined a test pilot school after the war in early 1946.

“Yeager has a reputation for being tough and sometimes cantankerous,” reflected Frank Vizard in a 1988 feature (included below) in Popular Science about the man and his accomplishment. “The eagle-eyed West Virginia native is a humorous speaker, and there is nothing shy about the man who rose to become brigadier general.”

X-1 aircraft Chuck Yeager
The X-1 measured a little less than 31 feet from tip to tail. National Air and Space Museum

Before his famous flight, planes had certainly gone very fast. “During World War II, aircraft were approaching the speed of sound,” says Bob van der Linden, a curator for special purpose aircraft at the Smithsonian National Air and Space Museum, where the X-1 hangs today. Fighter planes during the war might have flown faster than 400 or even 500 mph in a dive. At those kinds of rapid speeds, “air builds up in front of the airplane, and compresses,” van der Linden explains. That could cause the aircraft to come apart in the air, or crash.

That’s where the idea of the “sound barrier,” came from, he says—as if the speed of sound were an obstacle that couldn’t be penetrated. “Engineers knew it was a tough problem.” The solution was the X-1 transonic research aircraft that Yeager piloted. The smoothness he experienced was “a pleasant shock to him and everyone else,” van der Linden reflects. Supersonic flight may now be routine in the sense that military aircraft like F-16s are capable of doing it, but it remains a pricey, fuel-chugging endeavor.

As an experimental aircraft, the success of the X-1 “started a whole program of research aircraft that’s going on to this day,” van der Linden notes. For example, NASA’s present-day X-59 promises to fly faster than the speed of sound, but without making the iconic supersonic boom.

But Yeager, of course, did it first, 73 years ago this past October. In the January 1998, issue, Popular Science marked that moment with a look back at the historic flight—and the man who did it. We’ve reprinted that feature, below.

Chuck Yeager X-1
The key date: October 14, 1947. National Air and Space Museum

The Last Hero Pilot: Fifty years ago, aviator Chuck Yeager was the first to break the sound barrier. It turns out he was the last of his kind.

By Frank Vizard

The fighter plane draws a thin, white line across the blue sky, passing overhead in silence for some 20 seconds before the double clap of a sonic boom breaks the desert quiet. The pilot is Chuck Yeager, once again cracking the sound barrier, 50 years to the minute after he became the first man to do so.

Yeager, a spry 74 years old, is flying an F-15 Eagle over Edwards Air Force Base, just outside Lancaster, California. The aircraft goes supersonic effortlessly, a far cry from the diminutive X-1 flown by Yeager on October 14, 1947. As on that day, Yeager is accompanied by Bob Hoover, flying high chase in an F-16 rather than in the FP-80 he piloted on the historic mission 50 years earlier.

From the ground, these modern planes look like flies zigzagging and double-looping against an enormous skylight—a feeling that stays with you until a black, stealthy F-117 fighter comes in low and silent over the hanger behind you. It too is marking the occasion in showcase fashion. If you’re facing the right way, you see it coming. But even so, there isn’t time to do more than drop your jaw before the plane is gone. Then you hear the roar of its engines, and you realize that under other circumstances, you’d count yourself fortunate to be still alive.

The irony surrounding the 50th anniversary of the breaking of the sound barrier is that the two most modern planes in the Air Force’s arsenal, the F-117 fighter and the B-2 bomber, are subsonic, having traded speed for stealth. Yet in 1947, speed was everything. From the military’s perspective, speed promised a combat advantage. But flying faster than the speed of sound—Mach 1—was a barrier many thought couldn’t be crossed.

And they had good reason to think so. Just the year before, a plane flown by British pilot Geoffrey de Havilland had disintegrated in the attempt. The problem was called compressibility, but that didn’t begin to describe its seriousness. As a plane approached the sound barrier, the speed of the air passing over the thick wings of that era’s aircraft exceeded Mach 1, producing shock waves that could tear apart the plane.

The solution, devised by engineers at Bell Aircraft, was a thin-winged plane with the outline of a .50-caliber bullet, a shape known to be stable at supersonic speeds. Providing 6,000 pounds of thrust to the orange XS-1 (the plane’s name was later shortened to X-1) were four rocket engines that could be turned on sequentially, enabling the pilot to control the amount of power being used.

The flight of the X-1 is the link between the Wright brothers’ first flight at Kitty Hawk, North Carolina, in 1903 and the Apollo 11 moon landing in 1969. Yeager’s story is now the stuff of myth, and he has told it many times. A World War II ace flying a P-51 Mustang, Capt. Yeager was picked by the Air Force, itself only a few weeks old, to move aviation into the supersonic era. Lt. Hoover, another ace and the best acrobatic flyer of his generation, was cast in the role of sidekick and backup pilot. Both were hotshot aviators who flew by instinct. Adding the technical expertise was Capt. Jack Ridley. a pilot with impressive academic credentials who would serve as flight engineer.

Theoreticians had not anticipated the problems associated with the first test flights. A series of small fires gave Yeager nightmares about being trapped in the cockpit surrounded by flames and unable to escape. The X-1, now dubbed Glamorous Glennis in honor of Yeager’s wife, was difficult to handle. “Abuse the plane, and it would bite you,” says Yeager. A steering wheel replaced the traditional stick for better control. But as the X-1 approached Mach 1, it was experiencing the effects of compressibility.

Ridley, though, had an idea how to fix the problem, and his solution is commonly used on aircraft today. Elevators, flaps on the horizontal stabilizer that intersected the tail, were normally used to correct any unwanted up-and-down pitching motion. But as the X-1 approached Mach 1, shock waves were forming around the elevator hinges, causing Yeager to lose control of the plane. Ridley rigged up some controls that allowed Yeager to move the entire horizontal stabilizer in small increments, so he could compensate for the buffeting the plane was experiencing, effectively bypassing the elevators and preventing shock waves from wreaking havoc on the controls.

Chuck Yeager
Yeager reenacted his flight in 1997—this time in an F-15. John B. Carnett/Popular Science

On the morning of October 14, 1947, the X-1 was once again carried aloft by its B-29 mother ship. Yeager, despite having broken two ribs in a horse-riding accident just days before—a fact known only to Ridley—boarded the X-1 for its ninth flight. Forever the consummate engineer, Ridley handed Yeager a 10-inch length of broomstick so he could pull down the hatch with one hand, sparing his sore ribs. Moments later, the X-1 slipped out from under the belly of the B-29 bomber at 20,000 feet. Expectations were high, but so was the danger.

“l was concerned,” Hoover says today. “It was the most dangerous mission I was ever associated with. There was no ejection seat. If Yeager had to bail out, and the wing didn’t kill him, the tail would.” As it happened, a few weeks later, Hoover would break both of his own legs bailing out of another plane after its ejection seat failed.

Compounding the danger was the fuel for the rocket engines, a tank of liquid oxygen so cold it frosted the X-1′s outer skin. The oxygen would be mixed with alcohol and water from a second tank. The flight would be necessarily short—at full power, the X-1 consumed its 4,680-pound fuel supply in 2 ½ minutes.

Yeager accelerated quickly and, at a height of 42,000 feet, broke the sound barrier at Mach 1.06—approximately 700 mph—in what was a remarkably smooth transition into supersonic flight. Yeager maintained his speed for 20 seconds, then glided in for a landing. The entire mission had lasted 14 minutes.

Asked today if he was surprised when he achieved Mach I on that particular flight, Yeager pauses, as if to decide whether such an emotion would indicate a weakness. “I was surprised,” he says finally. “We didn’t know we were going to do it.”

Yeager has a reputation for being tough and sometimes cantankerous, and is perhaps the polar opposite of the silent loner depicted in The Right Stuff, the 1983 film that portrayed the era’s test pilots and first astronauts. The eagle-eyed West Virginia native is a humorous speaker, and there is nothing shy about the man who rose to become brigadier general. His salesmanship is almost as legendary as his flying prowess. “You’ve heard about the salesman who could sell a refrigerator to an Eskimo,” says Bob Cardenas, pilot of the B-29 that carried the X-1 aloft. “He’s a piker compared to Yeager.”

The Right Stuff did accurately portray the disparity between the relatively unheralded work of test pilots and the subsequent publicity machine that rolled unchecked for astronauts. Bridging the gap between the two, Yeager went on to train 19 astronauts while he was commandant of the Air Force’s Aerospace Research Pilot School from 1962 to 1966. Yeager also served as a wing commander in the Vietnam War, bringing his combat experience to a younger generation of fighter pilots.

He officially retired in 1975 but has worked for the Air Force in a consulting role ever since, contributing his expertise to the development of today’s airplanes. But 50 years after the flight of the X-1, Yeager is “finally giving back the keys,” he says. “l’ve been at this long enough. I’m going out on top before some doctor grounds me.”

In the course of his long career, Yeager has flown more than 330 types of aircraft. He admits that combat was his biggest thrill as a pilot, but says “flying the X-1 was probably the most useful thing I’ve done.”

Yeager’s departure marks the end of an era, one in which pilots have achieved national stardom. The role of the pilot is diminishing, Yeager acknowledges, as the Air Force moves into the 21st century. Many modern aircraft can stay in the air only with computer assistance. Fighter crews today never see each other, unlike the dogfights of old. Instead, they fire missiles while still miles away from the enemy.

Chuck Yeager
Yeager in 2015. National Air and Space Museum

“It’s launch and get out,” says Yeager. “You don’t jeopardize a $150 million aircraft. Stealth is the key to survivability.”

The development of remotely piloted aircraft now on the drawing boards takes the pilot out of the cockpit entirely for hazardous missions. Surprisingly, Yeager doesn’t see this as bad news. “Technology has removed much of the stress and danger that made being a pilot similar to being a matador,” he says. “Everything they develop keeps the longevity of the pilot in mind.”

And that’s a good trade-off. Future pilots may not attain the heroic status of Yeager, but more of them will live to be 74.

The story titled “The Last Hero Pilot” originally appeared in the January, 1998 edition of Popular Science.