Question

What kind of forces is responsible for airframe drag?

(a) Forces resulting from external flow

(b) Forces resulting from internal flow

(c) Forces resulting from discontinuous flow

(d) Forces resulting from continuous flow

The question was posed to me in a national level competition.

My question comes from Thrust Producing Power Plant in section Aircraft Force Systems and the Equations of Motion of Aircraft Performance

Answer 1

Right choice is (a) Forces resulting from external flow

For explanation I would say: The external flow can result in generation of forces. These forces that are caused due to external flow is known as airframe drag. In general there are three types of drags. They are parasitic drag, induced drag and wave drag.