Critical Mach number Critical Mach number In aerodynamics, the critical Mach number (Mcr or M* ) of an aircraft is the lowest Mach number at which the airflow over some point of the aircraft reaches the speed of sound, but does not exceed it. At the lower critical Mach number, airflow around the entire aircraft is subsonic. At the upper critical Mach number, airflow around the entire aircraft is supersonic. For an aircraft in flight, the speed of the airflow around the aircraft differs considerably in places from the airspeed of the aircraft; this is due to the airflow having to speed up
Mach Song population segments not reached by their media partners. On certain issues, Mach Song Media mobilizes local faith and community organizations to reach deep into their constituencies. So far they have worked with over 200 such organizations on various issues and have the capacity to reach 1,000 faith and community organizations in the Vietnamese communities across the US. "Boat People SOS" has invested over 1 million dollars to develop its own network of Vietnamese-language mass media. This network includes Mach Song monthly publication, Mach Song radio programs and Mach Song television programs. If necessary, Mach Song can readily increase the circulation