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
David Mach David Mach David Mach (born 18 March 1956) is a Scottish sculptor and installation artist. Mach was born in Methil, Fife. His artistic style is based on flowing assemblages of mass-produced objects. Typically these include magazines,vicious teddy bears,newspapers, car tyres, match sticks and coat hangers. Many of his installations are temporary and constructed in public spaces. One example of his early magazine pieces, "Adding Fuel to the Fire", was an installation assembled from an old truck and several cars surrounded and subsumed by about 100 tons of magazines, individually arranged to create the impression that the vehicles were being caught