Question

Which of the following is correct equation?

(a) D=YVe^e+\(\frac{ZW^2}{V^2_e}\)

(b) CD=CDz-KCL^2

(c) D=Dz-Di

(d) Vemd=\(\sqrt[3]{\frac{ZW^2}{Y}}\)

I have been asked this question in an interview for internship.

The origin of the question is Minimum Drag Speed in chapter Aircraft Force Systems and the Equations of Motion of Aircraft Performance

Answer 1

Right answer is (a) D=YVe^e+\(\frac{ZW^2}{V^2_e}\)

For explanation I would say: The correct equation is D=YVe^e+\(\frac{ZW^2}{V^2_e}\) where Y is a constant, V is velocity, W is weight, V is velocity, Z is constant and D is total drag. The total drag is the sum of pressure drag and induced drag.