Critical Mach number and slow down as it travels around the aircraft's structure. When the aircraft's airspeed reaches the critical Mach number, the speed of the airflow in some areas near the airframe reaches the speed of sound, even though the aircraft itself has an airspeed lower than Mach 1.0. This creates a weak shock wave. As the aircraft exceeds the critical Mach number, its drag coefficient increases suddenly, causing dramatically increased drag, and, in an aircraft not designed for transonic or supersonic speeds, changes to the airflow over the flight control surfaces lead to deterioration in control of the aircraft. In aircraft
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