Hmmmm how have you heard of Yeager but not of X-1??? Hehe anways, the Bell X-1 was the experimental aircraft that he flew to break the sound barrier on October 14th, 1947 at an altitude of 43,000 feet. His max speed was 700mph or mach 1.06... The information was not disclosed to the public until June of the following year though... Anyway, that's you history lesson for the day
