FAA Flight Instructor Airplane (FIA)Aerodynamics and Principles of FlightMedium
A CFI explains to a client that on a cambered (non-symmetrical) airfoil operated at cruise angle of attack, the center of pressure is located relatively far aft on the chord. As angle of attack is gradually increased toward (but not exceeding) the critical angle of attack, what happens to the center of pressure?
- AIt remains fixed at the same chordwise location regardless of AOA
- BIt moves aft continuously as AOA increases
- CIt moves forward along the chord as AOA increases
- DIt oscillates randomly with no predictable pattern
Show answer & explanationAnswer & explanation
Correct answer: C. It moves forward along the chord as AOA increases
On a cambered airfoil, as AOA increases toward the critical angle, the center of pressure moves forward along the chord. This forward CP travel creates a nose-up pitching tendency that can contribute to the airplane's natural tendency to increase AOA further if unchecked, which is a factor in longitudinal stability design.
Why the other options are wrong
- A. CP location on a cambered airfoil is not fixed; it shifts with AOA, unlike a symmetrical airfoil where CP stays relatively constant.
- B. CP moves aft rapidly only after the stall (beyond critical AOA), not while approaching it.
- D. CP movement follows a predictable pattern related to AOA, not randomness.
Center of Pressure Travel
On a cambered airfoil, the center of pressure moves forward as AOA increases toward the critical angle, then moves rapidly aft once the wing stalls, affecting pitch stability.
- Forward CP movement at increasing AOA can contribute to pitch-up tendency
- After stall, CP moves rapidly aft, contributing to pitch-down (nose drop)
- Symmetrical airfoils have a nearly fixed CP regardless of AOA
Memory trick: CP creeps forward as AOA climbs, then bolts aft after the stall