Christine M. Darden
NASA Langley Res. Ctr., Hampton, VA 23665
During NASA's high-speed research program, a renewed emphasis has been placed on understanding and reducing the sonic boom generated by an airplane during flight at speeds faster than the speed of sound. When the current program was initiated in 1990, a three-pronged approach was instituted: (1) human acceptabilities studies; (2) atmospheric propagation studies; and (3) airplane design and operation studies. Original goals were to use special design and operation techniques to reduce the sonic boom to levels which would be acceptable for either unrestricted overland flight or overland flight through low-populated corridors. Recent human response studies have indicated that sonic booms are much more disturbing than continuous noise sources such as engines around airports; thus any commercial overland supersonic flight is highly unlikely within the near future. These conclusions have resulted in a redirection of the sonic-boom program. This talk will discuss current efforts at sonic-boom softening (small design changes), continuing efforts to understand the impact of the atmosphere on the rise time of the sonic-boom signature, and strategies to understand what impact, if any, the sonic boom has on marine life.