Question

Consider external flow dynamic pressure as 2000psf and static pressure as 800psf. find the approximate value of Mach number.

(a) 1.9

(b) 5

(c) 4.5

(d) 2.78

The question was asked in exam.

My enquiry is from Flight Mechanics topic in chapter Performance and Flight Mechanics of Aircraft Design

Answer 1

Correct answer is (a) 1.9

Explanation: Mach number = (dynamic pressure / (0.7*Static pressure))^0.5

= (2000 / (0.7*800))^0.5

= 3.571^0.5 = 1.88 = 1.9.