The Quest for Quiet Supersonic Flight
NASA's X-59 experimental aircraft has completed its second test flight, kicking off an intensive series of dozens of planned test flights that will build toward the program's ultimate goal: demonstrating to regulators that commercial supersonic flight over land is technically achievable without generating the ground-level sonic booms that led to the ban on overland supersonic transport operations in the United States more than five decades ago.
What Makes the X-59 Different
Conventional supersonic aircraft generate sonic booms because of the way shock waves interact with each other and stack into a sharp pressure signature that reaches the ground as a disruptive double boom. The X-59 is designed to prevent this stacking through a highly elongated fuselage shape and carefully engineered external geometry that causes the shock waves generated at different parts of the aircraft to reach the ground at different times, spreading the pressure pulse rather than concentrating it.
The result—if the design performs as predicted—is a much quieter low-level thump rather than a startling boom. NASA has been calling this the low-boom signature, and the X-59's specific geometry is optimized to produce a thump that might be heard at approximately 75 perceived decibels at ground level—roughly equivalent to the sound of a car door closing, compared to the 90+ decibels of a conventional supersonic aircraft's boom.
