Question

What is the critical mach number for most subsonic aircraft?

(a) Around 0.8

(b) Around 2

(c) Around 1

(d) Around 1.5

This question was posed to me during an interview.

My enquiry is from Aircraft Force Systems in section Aircraft Force Systems and the Equations of Motion of Aircraft Performance

Answer 1

The correct choice is (a) Around 0.8

The explanation: For most subsonic aircraft the critical mach number occurs typically at mach number 0.8. At this mach number the local flow at points on the aircraft becomes supersonic and shock waves begin to form.