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
Ford Mustang Mach 1 rear axle was optional, and the 428 CJ/SCJ included a "traction lok" with a 3.91 or 4.30 ratio, 31 spline axle shafts and a nodular case. In 1970, the 3.91 ratio was a "traction-lok", while the 4.30 ratio was a Detroit Locker. Mach 1s came with upgraded suspension to varying degrees dependent upon powertrain choices. Big block cars had front shock tower reinforcement, thicker sway bars (no rear bar for 69), and heavier springs and shocks. 428 CJ/SCJ 4 speed cars also came with staggered rear shocks. Standard on Mach 1s was a fierce but cosmetic hood scoop that had