Schlieren images reveal supersonic shock waves
NASA researchers in California are using a modern version of a 150-year-old German photography technique to capture images of shock waves created by supersonic airplanes. Over the past five years scientists from NASA's Armstrong Flight Research Center at Edwards Air Force Base and Ames Research Center at Moffett Field have teamed up to demonstrate how schlieren imagery, invented in 1864 by German physicist August Toepler, can be used to visualize supersonic flow phenomena with full-scale aircraft in flight. The results will help engineers to design a quiet supersonic transport. Although current regulations prohibit unrestricted overland supersonic flight in the United States, a clear understanding of the location and relative strength of shock waves is essential for designing future high-speed commercial aircraft.