At what angle of attack does a symmetric airfoil generate zero lift?

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Multiple Choice

At what angle of attack does a symmetric airfoil generate zero lift?

Explanation:
A symmetric airfoil has no camber, so at zero angle of attack the flow sees a symmetric pressure distribution on the two surfaces. That symmetry means there’s no net vertical force, i.e., zero lift. As soon as you increase the angle of attack even slightly, the top surface accelerates the flow more than the bottom, lowering the pressure above and raising it below, which creates upward lift. Conversely, a small negative angle would produce downward lift. So the angle of attack that yields zero lift for a symmetric airfoil is zero degrees.

A symmetric airfoil has no camber, so at zero angle of attack the flow sees a symmetric pressure distribution on the two surfaces. That symmetry means there’s no net vertical force, i.e., zero lift. As soon as you increase the angle of attack even slightly, the top surface accelerates the flow more than the bottom, lowering the pressure above and raising it below, which creates upward lift. Conversely, a small negative angle would produce downward lift. So the angle of attack that yields zero lift for a symmetric airfoil is zero degrees.

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