Mach number a small area around the object's leading edge. (Fig.1b) Fig. 1. "Mach number in transonic airflow around an airfoil; M < 1 (a) and M > 1 (b)." When an aircraft exceeds Mach 1 (i.e. the sound barrier), a large pressure difference is created just in front of the aircraft. This abrupt pressure difference, called a shock wave, spreads backward and outward from the aircraft in a cone shape (a so-called Mach cone). It is this shock wave that causes the sonic boom heard as a fast moving aircraft travels overhead. A person inside the aircraft will not hear this.
Ford Mustang Mach 1 tendency to understeer more than the IRS equipped SVTs and lower CG and lower curb weight Bullitt GTs with the same basic suspension and brakes. Limited in production, the 2003 and 2004 Mach 1s ended with the New Edge body platform, the discontinuation of the Fox framed unibody, and the introduction of the first new frame design since 1979 the s-197 with 9,652 2003's and 7,182 2004's being built, contrary to the Mach 1 originally being advertised as a one-year limited run model with production set at 6,500 cars. The Mach 1 nameplate could possibly make a return in 2018.