supersonic speed
Speed greater than that at which sound travels, measured in Mach numbers. In dry air at 0°C/32°F, sound travels at about 1,170 kph/727 mph, but its speed decreases with altitude until, at 12,000 m/39,000 ft, it is only 1,060 kph/658 mph.
When an aircraft passes the sound barrier, shock waves are built up that give rise to sonic boom, often heard at ground level. US pilot Captain Charles Yeager was the first to achieve supersonic flight, in a Bell VS-1 rocket plane on 14 October 1947.
When an aircraft passes the sound barrier, shock waves are built up that give rise to sonic boom, often heard at ground level. US pilot Captain Charles Yeager was the first to achieve supersonic flight, in a Bell VS-1 rocket plane on 14 October 1947.
© RM 2012. Helicon Publishing is division of RM.
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