# What angle does the Mach wave makes with the flow direction ?

An airplane flying at a Mach number of 2.2 makes a Mach wave at the nose. What angle does it make with the flow direction ?

Mach wave is formed by pilling up of pressure disturbances when the object is flying at a speed above the speed of sound. Mach wave is due to the weak disturbances in the flow. Mach angle is the angle between the Mach wave and the direction of the movement of the object. It depends only on the Mach number. Mach angle is given by \(\mu\).

\[\mu = {\sin ^{ – 1}}\left( {\frac{1}{M}} \right)\]

Here, Mach number is \(2.2\). Therefore, Mach angle

\[\mu = {\sin ^{ – 1}}\left( {\frac{1}{{2.2}}} \right) = {27.036^\circ }\]