Aerodynamics 1

Question 1

What are the two main aerodynamic forces which act on an aircraft?

Answer 1

• Friction caused by shear layers tangential to surface.
• Pressure caused by changes in air velocity perpendicular to surface.

Question 2

Explain the two methods of estimating parasitic drag.

Answer 2

Equivalent skin-friction method - apply a skin-friction coefficient to S_wet / S_ref

Component build up method - estimates subsonic parasitic drag of each aircraft component

Question 3

Describe drag due to lift (induced drag)

Answer 3

Induced drag is caused by the rotational energy left in the tip vortices. This energy loss manifests as drag.