A negatively cambered airfoil has a zero-lift angle of attack that is negative.

• A. Positive
• B. Zero
• C. Negative
• D. Undefined

Answer: (C)

Camber shifts the angle of attack where lift goes to zero. The zero-lift angle of attack is the AoA at which the lift coefficient is zero, and its sign depends on the camber direction. If the camber is positive, the airfoil generates lift even at small or zero AoA, so you must rotate the wing to a negative AoA to reach zero lift. If the camber is negative, the wing tends to produce downward lift at zero AoA, so you must rotate the wing to a positive AoA to cancel that lift and reach zero lift. Therefore, for a negatively cambered airfoil, the zero-lift angle of attack is positive, not negative. The statement as written is not correct. For negatively cambered airfoils, zero lift occurs at a positive angle of attack; for positively cambered airfoils it occurs at a negative angle, and for a symmetric airfoil it occurs at zero.