FAA Private Pilot Airplane (PAR)Aerodynamics and Aircraft SystemsMedium
An airplane is flying straight and level when a wind gust momentarily banks the right wing down without changing heading. The airplane's wings have noticeable dihedral. Assuming the pilot makes no control input, what will the airplane tend to do?
- AContinue rolling further into the bank due to overbanking tendency
- BEnter a spiral dive as sideslip increases the bank angle
- CRemain in the banked attitude with no tendency to change
- DRoll back toward a wings-level attitude due to increased lift on the lower wing
Show answer & explanationAnswer & explanation
Correct answer: D. Roll back toward a wings-level attitude due to increased lift on the lower wing
Wing dihedral provides lateral (roll) stability. When one wing drops, the airplane begins to sideslip toward the low wing, which increases the effective angle of attack on the lower wing relative to the upper wing. This produces more lift on the lower wing, creating a restoring rolling moment back toward wings-level flight.
Why the other options are wrong
- A. Overbanking tendency is associated with steep turns and airspeed differential between wings, not dihedral response to a gust.
- B. A spiral dive would result from insufficient stability, the opposite of what dihedral provides.
- C. Dihedral specifically produces a restoring tendency, so the airplane will not remain in the bank.
Dihedral Effect
The tendency of an airplane with wing dihedral to produce a rolling moment that returns the wings to level flight after being displaced in bank, due to sideslip creating unequal lift between the wings.
- Wing dihedral is the upward angle of the wings from the wing root to tip
- Sideslip toward the lower wing increases its effective AOA, increasing lift
- This creates lateral (roll) static stability
Memory trick: Dihedral is a built-in autopilot for wings-level flight.