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
Ford Mustang Mach 1 (without Ram Air) remained optional on every model. Chart does not reflect the Boss 351 variant of the 351 Cleveland or 250cid I6, as neither were available in the Mach 1 package. The 1972 R-code 351HO package - essentially the solid-lifter Boss 351 motor from 1971 with a reduction in compression from 11.0:1 to 8.8:1 - is listed here, as it was available with the Mach 1 package that year. The Mach 1 name continued with the advent of the Mustang II in 1974. The downsized vehicle - fitted with the 2.8 L V6 rated at - outsold the Mach