How does the center of pressure move with angle of attack?

• A. The center of pressure remains fixed regardless of angle of attack.
• B. The center of pressure moves with angle of attack; the CP location shifts along the chord.
• C. The center of pressure only moves at supersonic speeds.
• D. The center of pressure always moves toward the trailing edge with AoA.

Answer: (B)

The center of pressure is the point where the resultant aerodynamic force can be considered to act. It isn’t fixed; it depends on how the lift is distributed over the wing, and that distribution changes as the angle of attack changes.

When you change the angle of attack, the pressure differences on the upper and lower surfaces shift. This changes the lift distribution along the chord and thus the moment produced by the pressure forces about a reference point. Since the center of pressure is the point where the overall lift force can be thought to act to produce that moment, its location moves along the chord as AoA changes.

For subsonic flight, the aerodynamic center of the airfoil is near the quarter-chord, where the pitching moment is roughly independent of AoA, but the center of pressure still shifts with AoA relative to that point. In short, the CP moves along the chord with angle of attack, rather than staying fixed.

The other options imply no shift or shifts only under specific conditions, which isn’t generally true, so the correct idea is that the center of pressure moves with angle of attack, changing its position along the chord.