The first supersonic flight was in 1947. It was just above the speed of sound. Which altitude would you expect Captain Yeager to have used for his flight?
Answers
This is part of a SPACE.com series of articles on the Greatest Moments in Flight, the breakthrough events that paved the way for human spaceflight and its next steps: asteroid mining and bases on the moon and Mars.
A booming thunder roared across the clear skies of the Mojave Desert on Oct. 14, 1947, as U.S. Air Force Capt. Chuck Yeager nudged an experimental rocket-powered plane faster than the speed of sound. Though only a handful of people realized it at the time, an aviation record had been set.
nd barrier with Col. Chuck Yeager at the controls on Oct. 14, 1947.
Credit: NASA
A bullet-shaped plane, the Bell X-1 (originally designated the XS-1), was created in a collaboration between NASA's Langley Research Center and the U.S. military. It was modeled after a .50 caliber machine gun bullet, an object known to be stable as it exceeded the speed of sound. According to NASA, "The X-1 was the first high-speed aircraft built purely for aviation research purposes." Unlike other aircraft, it was never intended for production.
Four rocket engines propelled the X-1, and it was built to absorb 18 times the force of gravity. Unlike most planes, it didn't take off from the ground, but was instead dropped from the belly of a B-29 Superfortress, rapidly accelerating in the air on only a few minutes worth of fuel before gliding back to the dry lakes below.
The plane, nicknamed the "Glamorous Glennis" for Yeager's wife, slowly approached the sound barrier over the course of nine flights. Muroc Air Force Base — now known as Edwards Air Force Base — in the empty southern California desert provided an ideal spot for testing a variety of experimental vehicles, including the X-1.
The pilot
The man who would become the most famous test pilot in American history was born in West Virginia on Feb. 13, 1923. Charles Elwood "Chuck" Yeager enlisted as a private in the U.S. Army Air Corps at the age of 18 and served in World War II, where he flew 64 combat missions.
Like many of his generation, Yeager enrolled in the military in 1941. In a 2017 interview with Forbes, Yeager said he was a gifted mechanic who had never seen an airplane before he turned 18.
"But I noticed that, as a mechanic, my hands were always greasy while the pilots' were clean — and they had good-looking girls on their arms. Flying looked pretty good to me," he told Forbes.
The military required a college education for its pilots, but when they didn't get enough applicants for the cadet flier program in 1942, they dropped the requirements to a high school diploma.
"With my visual acuity and understanding of mechanics, I was really a hell of a lot better than the cadets. From there on, I was in the right place at the right time," he told Forbes.
In 1945, he was assigned as a maintenance officer to the Flight Test Division at Wright Field, Ohio, flight-testing the planes. Col. Albert Boyd, in charge of the test program for the Air Force, invited him to become a test pilot, and Yeager accepted, transferring to Muroc to enroll in the Flight Performance School. It was there that Yeager was selected to be the first person to attempt to exceed the speed of sound.
t.
On Oct. 14, 1947, Yeager and the X-1 were dropped from the B-29, and quickly accelerated away. When the controls locked up, he successfully used the horizontal stabilizer to keep the plane stable at an altitude of 43,000 feet (13,000 meters). As the plane accelerated to a speed of 700 mph (1,127 km/h), or Mach 1.06, controllers on the ground heard the first sonic boom. (The end of a bullwhip moves faster than the speed of sound. Some say the "crack" is a small sonic boom.)
After exceeding the speed of sound, the buffeting decreased, creating a smooth short flight. The plane remained supersonic for approximately 20 seconds before Yeager turned off two of the four engines and slowly decelerated.
Chuck Yeager continued to act as a flight consultant for the air force until his last flight on October 14, 1997.
Yeager continued to fly experimental aircraft for the Air Force, and was appointed director of the Space School, NASA's precursor, where he trained astronauts to prepare for launch. He flew more than 120 combat missions in Vietnam. After 34 years in the military, he retired in 1975 at the rank of brigadier general, though he continued to serve as a consultant. His last flight as a military consultant occurred 50 years to the day after he broke the sound barrier, at the age of 74.