Question

Surface friction drag corresponds to 35% of the lift independent drag whereas the profile drag leads to 65% of the lift independent drag.

(a) True

(b) False

The question was posed to me during an interview for a job.

This intriguing question originated from Drag Force topic in chapter Aircraft Force Systems and the Equations of Motion of Aircraft Performance

Answer 1

Right option is (b) False

To explain I would say: Lift independent drag is divided into two types. They are the surface friction drag and the profile drag. Surface friction drag corresponds to 75% of the lift independent drag whereas the profile drag leads to 25% of the lift independent drag.