On this day, 78 years ago, on October 4, 1947 (August 20, 1947, the lunar calendar), humans broke through the speed of sound for the first time. Yeager and "Charming Glennes" together On October 4, 1947, Chuck Yeager became the first person to fly supersonic. The former U.S. fighter pilot boarded a Bell X-1 jet. Taking off from a secret army base in California. A few minutes later, he reached 960 kilometers per hour, breaking the sound barrier. The plane Yeager piloted, named Charming Glennes, is powered by a new type of rocket and has a streamlined fuselage to reduce the bumps caused by acceleration. Other countries are also improving their aircraft to exceed the speed of sound-the Mach-1.