Question

If flow has Mach number of 1.2 then, determine the ratio of total and external flow dynamic pressure.

(a) 2.4

(b) 1

(c) 3.8

(d) 5.6

The question was asked in class test.

The doubt is from Flight Mechanics in chapter Performance and Flight Mechanics of Aircraft Design

Answer 1

Correct option is (a) 2.4

Best explanation: Given, Mach number M = 1.2

Ratio of total pressure and external flow dynamic pressure = (1.428/M^2)*[1+0.2*M^2]^3.5

= (1.428/1.2^2)*[1+0.2*1.2^2]^3.5

= (1.428/1.2^2)*[1+0.288]^3.5

= 2.40.