Question

Which of the following is the correct relation between minimum power speed and minimum drag speed?

(a) Vmp=\(\frac{1}{\sqrt[2]{3}}\)Vmd

(b) Vmp=\(\frac{1}{\sqrt[4]{3}}\)Vmd

(c) Vmp=\(\frac{1}{\sqrt[3]{3}}\)Vmd

(d) Vmp=\(\frac{1}{\sqrt[4]{5}}\)Vmd

The question was asked during an online exam.

My question comes from Aerodynamic Relationships topic in portion Aircraft Force Systems and the Equations of Motion of Aircraft Performance

Answer 1

Correct choice is (b) Vmp=\(\frac{1}{\sqrt[4]{3}}\)Vmd

To explain: At steady state flight condition the thrust produced by the aircraft is same as the drag produced by the aircraft i.e. T=D. The relation between minimum drag speed and minimum power speed is given by Vmp=\(\frac{1}{\sqrt[4]{3}}\)Vmd where Vmd is minimum drag speed and Vmp is minimum power speed.