Which statement is true about a symmetrical airfoil?

Which statement is true about a symmetrical airfoil?

• A. It has a constant center of pressure
• B. It is easier to construct than a nonsymmetrical airfoil
• C. It always produces more lift at the same angle of attack
• D. It never stalls

Answer: (A)

The main idea here is how the airfoil’s pressure distribution and resulting force behave with angle of attack. For a symmetric airfoil, the pressure distribution is balanced about the chord, and the aerodynamic center—roughly at the 25% chord point—remains at essentially the same fore‑aft location as you change the angle of attack. Because the aerodynamic center does not move with angle of attack, the center of pressure (the point where the resultant lift acts) stays effectively constant over the usual operating range. That’s why the statement about a constant center of pressure is considered true for a symmetric airfoil. Other statements don’t fit as well. Symmetry doesn’t guarantee easier manufacturing or general ease of construction versus a nonsymmetric shape. At the same angle of attack, a symmetric airfoil does not inherently produce more lift than a cambered one; in fact, a cambered airfoil typically generates more lift at the same small angle of attack. And like any real airfoil, a symmetric one can stall if turned to a high enough angle of attack.

The main idea here is how the airfoil’s pressure distribution and resulting force behave with angle of attack. For a symmetric airfoil, the pressure distribution is balanced about the chord, and the aerodynamic center—roughly at the 25% chord point—remains at essentially the same fore‑aft location as you change the angle of attack. Because the aerodynamic center does not move with angle of attack, the center of pressure (the point where the resultant lift acts) stays effectively constant over the usual operating range. That’s why the statement about a constant center of pressure is considered true for a symmetric airfoil.

Other statements don’t fit as well. Symmetry doesn’t guarantee easier manufacturing or general ease of construction versus a nonsymmetric shape. At the same angle of attack, a symmetric airfoil does not inherently produce more lift than a cambered one; in fact, a cambered airfoil typically generates more lift at the same small angle of attack. And like any real airfoil, a symmetric one can stall if turned to a high enough angle of attack.