Airflow around an Aerofoil (2D)

081-01-02Pablo Asensio Martínez2026-04-011 min

Geometry

  • Chord Line: A straight line connecting the leading edge and the trailing edge.
  • Mean Camber Line: A line equidistant from the upper and lower surfaces.
  • Camber: The curvature of the aerofoil (distance between chord line and mean camber line).
    • Symmetrical Aerofoil: Camber is zero. Chord line = Mean camber line.
    • Positively Cambered: Produces lift at zero Angle of Attack.
  • Thickness: Maximum distance between upper and lower surfaces.
  • Angle of Attack ($\alpha$): The angle between the Chord Line and the Relative Airflow.
  • Angle of Incidence: The angle between the Chord Line and the Longitudinal Axis of the aircraft (fixed by design).

Aerodynamic Forces

  • Total Aerodynamic Reaction (TAR): The resultant force of all pressure and friction forces.
  • Lift ($L$): The component of TAR perpendicular to the Relative Airflow.
  • Drag ($D$): The component of TAR parallel to the Relative Airflow.

Significant Points

  • Center of Pressure (CP): The point through which the Lift acts.
    • Moves forward as Angle of Attack increases (for most subsonic aerofoils) until the stall.
  • Aerodynamic Center (AC): The point where the pitching moment coefficient is constant with changes in Angle of Attack.
    • Typically located at 25% of the chord (subsonic).
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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