Mach number which was also unit-first, and may have influenced the use of the term Mach. In the decade preceding faster-than-sound human flight, aeronautical engineers referred to the speed of sound as "Mach's number", never "Mach 1". Mach number is useful because the fluid behaves in a similar manner at a given Mach number, regardless of other variables. As modeled in the International Standard Atmosphere, dry air at mean sea level, standard temperature of , the speed of sound is . The speed of sound is not a constant; in a gas, it increases as the absolute temperature increases, and since atmospheric
Bluebird Mach 1.1 Bluebird Mach 1.1 Bluebird Mach 1.1 (CMN-8) was a design for a rocket-powered supersonic land speed record car, planned by Donald Campbell but thwarted by his subsequent death during a water speed record attempt in "Bluebird K7" in early 1967. Donald Campbell decided a massive jump in speed was called for following his successful 1964 LSR attempt in "Bluebird CN7". His vision was of a supersonic rocket car with a potential maximum speed of 840 mph, referred to as "Bluebird Mach 1.1". Norris Brothers were requested to undertake a design study. Campbell, ever superstitious, chose a lucky date to hold