Question

For a cambered airfoil section lift is 30N. Airfoil is operating in such way that dynamic lift is 20N. Determine the lift co-efficient for the airfoil.

(a) 1.5

(b) 1.5N

(c) 0.5

(d) 0.5N

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Question is from Airfoil Selection-2 topic in portion Airfoil and Geometry Selection of Aircraft Design

Answer 1

Right choice is (a) 1.5

Easiest explanation: Given, sectional lift = 30N, dynamic lift=20N.

Lift co-efficient = section lift/dynamic lift = 30/20 = 1.5.