Ernst Mach of experimental physics concentrated on the interference, diffraction, polarization and refraction of light in different media under external influences. From there followed important explorations in the field of supersonic fluid mechanics. Mach and physicist-photographer Peter Salcher presented their paper on this subject in 1887; it correctly describes the sound effects observed during the supersonic motion of a projectile. They deduced and experimentally confirmed the existence of a shock wave of conical shape, with the projectile at the apex. The ratio of the speed of a fluid to the local speed of sound "v"/"v" is now called the Mach number. It
Beaujon Mach .07 Beaujon Mach .07 The Beaujon Mach .07 is a single-seat, American high-wing, tractor configuration ultralight aircraft. The aircraft is available as plans from Beaujon Aircraft of Ardmore, Oklahoma. Designed by Herbert Beaujon, the Mach .07 is named for its top speed of . Beaujon Aircraft publishes the plans along with six other designs in book form under the name "How to Build Ultralights". The Mach .07 was specifically designed to comply with the United States ultralight category and its FAR 103 "Ultralight Vehicles" rules, including the category's maximum empty weight. With the specified 250 cc Zenoah G-25 powerplant the aircraft