People often ask such a question: can the wing fly backwards? To answer this question, perform the following calculation. Consider airfoils with a zero-lift angle of −3°. The lift slope is 0.1 per degree.

(a) Calculate the lift coefficient at an angle of attack of 5°.

(b) Now imagine the same wing upside down, but at the same 5° angle of attack as part (a). Calculate its lift coefficient.

(c) At what angle of attack can the upside down airfoil produce the same lift as the original airfoil at an angle of attack of 5°?