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Science NASA and JAXA team up for silent supersonic aircraft
Science NASA and JAXA team up for silent supersonic aircraft | NASA and JAXA team up for silent supersonic aircraft |
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| by William Atkins | |
| Saturday, 10 May 2008 | |
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Page 1 of 2 Aircraft produce sound waves when traveling through air. These sound waves have a maximum speed at which they can travel. When the temperature is 70 degrees Fahrenheit (21.1 degrees Celsius), the speed that sound travels is approximately 1,129 feet per second (or 770 miles per hour), or 344 meters per second (or 1,238 kilometers per hour). At or above the speed of sound, an aircraft is traveling faster than the sound it makes. Thus, when an aircraft exceeds the speed of sound, it forces the sound it makes to go faster than it is capable of going. (An aircraft that travels at the speed of sound is said to be traveling at Mach 1. Thus, if an aircraft travels at Mach 2, it is going twice the speed of sound. If a supersonic aircraft should go over five times the speed of sound (Mach 5), then it is considered to be traveling at a hypersonic speed.) As speeds equal to or greater than the speed of sound, the resulting sound waves are compressed at the front end of the aircraft. They are contained inside a shock wave (or a region of disturbed air). Specifically, it is called a compressional head shock. Further back of the aircraft, air molecules try to fill in the void created by the compressed air. A rarefractional tail shock develops. Ultimately, the audible sound of a sonic boom is produced. And, the sharp noise of sonic booms continues to be generated as long as the aircraft travels at or faster than the speed of sound. Past problems and possible future solutions. Read on. |
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