Lateral Stability

081-04-05Pablo Asensio Martínez2026-04-011 min

Mechanism

When an aircraft rolls, the lift vector tilts and a Sideslip begins towards the lower wing (due to gravity).

  • Correct static lateral stability creates a rolling moment that raises the lower wing to restore level flight.

Stability Contributions

  1. Dihedral: Upward angle of wings. When sideslipping, the lower wing has a higher effective Angle of Attack than the upper wing -> More Lift -> Restoring Roll.
  2. Sweepback: The lower wing (advancing into the relative wind due to sideslip) presents a greater span/less sweep to the airflow -> More Lift -> Restoring Roll.
  3. High Wing vs Low Wing:
    • High Wing: Pendulum stability (fuselage hangs below wing) + Interference effect (fuselage directs airflow up over the wing roots) = Naturally stable.
    • Low Wing: Naturally less stable. Requires more Dihedral.

Anhedral

Downward angle of wings. Used on high-wing heavy transport aircraft (like C-17, BAe 146) or fighters to reduce excess lateral stability and improve maneuverability. Too much stability makes the aircraft hard to turn (Dutch Roll tendency).

Written and reviewed by

Pablo Asensio · 2026-04-01

Aeronautical engineer. Passed the thirteen EASA ATPL(A) theoretical knowledge exams studying from these very notes. Writes and reviews each topic against the Part-FCL Learning Objectives.

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