The Sound Barrier

Why did Chuck Yeager go to such a high altitude to break the sound barrier?

Sound travels approximately 760 miles per hour in the warm, dense air found close to sea level. The cooler and less-dense air is, however, the lower the speed of sound. Since air is less dense at higher elevations, physicists and engineers felt it would be easier to break the sound barrier at those elevations. Knowing the temperature and density of the air at 12,192 meters (40,000 feet) above sea level, scientists determined that the speed of sound would be reduced to only 660 miles per hour. As an added bonus engineers found that not only was the speed of sound slower at such elevations, but when the air has such low density, the parasitic drag (the drag due to friction), is very low as well. Therefore, to break the sound barrier, Yeager traveled as far up as 13,106 meters (43,000 feet) above sea level to both reduce the sound barrier and decrease the parasitic drag.


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