Symmetrical airfoils have which characteristic related to stall?

Symmetrical airfoils have which characteristic related to stall?

• A. Undesirable stall characteristics
• B. Excellent stall characteristics
• C. No stall characteristics
• D. Stall characteristics are unpredictable

Answer: (A)

The key idea is how airfoil camber affects stall behavior. A symmetrical airfoil has no camber, so its lift is zero at zero angle of attack and the pressure distribution is the same on both sides. As the angle of attack increases, the flow remains attached until a critical point, then separates abruptly. Without camber to smooth the transition and maintain attached flow, the stall comes on suddenly with a sharp drop in lift and loss of control effectiveness. That abrupt, unforgiving stall behavior is why symmetrical airfoils are said to have undesirable stall characteristics. The other options don’t fit because symmetric airfoils do stall, the stall is not considered excellent, and while the stall is predictable, it is typically abrupt rather than uncontrolled or completely unpredictable.

The key idea is how airfoil camber affects stall behavior. A symmetrical airfoil has no camber, so its lift is zero at zero angle of attack and the pressure distribution is the same on both sides. As the angle of attack increases, the flow remains attached until a critical point, then separates abruptly. Without camber to smooth the transition and maintain attached flow, the stall comes on suddenly with a sharp drop in lift and loss of control effectiveness. That abrupt, unforgiving stall behavior is why symmetrical airfoils are said to have undesirable stall characteristics.

The other options don’t fit because symmetric airfoils do stall, the stall is not considered excellent, and while the stall is predictable, it is typically abrupt rather than uncontrolled or completely unpredictable.