Basic Aerodynamics: Aircraft Control Mechanisms

Basic Aerodynamics

• Aircraft Axes and Planes of Rotation:

  • Longitudinal (roll) axis
  • Lateral (pitch) axis
  • Normal (yaw) axis

• Flight Controls: These manage aircraft movement.

• Elevators: Control pitch.

• Pitch Control:

  • Control surface area impacts pitch.
  • Control surface angular deflection affects pitch.
  • The moment arm influences pitch changes.
  • Angle of attack also plays a role in pitch.

• Alternative Pitch Controls:

  • Variable incidence tailplane: A tailplane that adjusts its angle of attack.
  • Stabilator: combines elevator and stabilizer functions
  • Elevons: control both aileron and elevator functions

• Rudder: Controls yaw.

• Yaw Control:

  • Area of the control surface is a factor in yaw.
  • Control surface deflection influences yaw.
  • Moment arm affects yaw control.
    • Engine-induced yaw is a phenomenon affecting yaw.

• Asymmetric Engine Yawing Moment: This occurs when an engine produces more thrust than the opposite engine.

  • Critical power unit is the key factor in this moment.

• Asymmetric Rolling Moment: Unbalanced force creating roll.

• Minimum Control Speeds:

  • Take-off speeds.
  • Landing speeds.
    • Vmc and Vmcg are minimum control speeds
    • Factors affecting Vmcg and Vmc are covered.
    • Vmcl, the minimum control speed for landing in a particular configuration, is also vital.
    • Vmcl(1out) is a specific Vmcl case.
    • Vmcl-2 is another variant of Vmcl.
    • Factors impacting Vmcl are detailed.

• Ailerons: These control roll.

• Roll Control: Ailerons and related controls manage roll

  • Flaperons are an aileron variant

• Wing Twist:

  • Geometry of twist.
  • Aerodynamic twist
    • Twisterons: Twisting ailerons
  • High-speed twist: A further variation in twist.
  • A comparison between high and low speed ailerons.
    • Roll spoilers.

Lift Generation

• Turbulent Flow: A type of airflow.

• Streamline Flow: Another type of airflow, with a smooth, predictable flow.

• Boundary Layer: A layer of air adjacent to a wing's surface.

• Laminar Boundary Layer: Smooth airflow near the wing surface.

  • Transition point is the location where the flow transitions.

• Turbulent Boundary Layer: Rough airflow near the wing surface.

  • Leading-edge separation creates a boundary layer problem

• Boundary-Layer Control: Methods to modify the boundary layer.

  • Blowing: adds air to the boundary layer.
  • Suction: removes air from the boundary layer.
  • Vortex generators: create vortices in the boundary layer.

• Two-Dimensional Flow: Analyzing airflow in a 2D plane.

• Stagnation Point: Point on an aerofoil where airflow joins the surface.

  • Impact of airflow on upper and lower surfaces of an aerofoil.

• Lift Production: - The generation of lift using various aerofoils. - Symmetrical and cambered aerofoils.

• Abbreviations:

  • VS: Stalling speed
  • VS0: Stalling speed (flaps at landing position).
  • VS1: Configuration-specific stalling speed.
  • VS1g: Stalling speed at 1g.
  • VSR: Reference stalling speed
  • VSR0: Reference stall speed (landing config).
  • VSR1: Configuration-specific reference stall speed.
  • VSW: Speed at which stall warning activates.
  • VX: Speed at which maximum climb gradient achieved.
  • VY: Speed at which maximum rate of climb attained.
  • WC: Wind component.
  • WED: Water-equivalent depth.

• Weight and Mass: Difference between weight (force) and mass (amount of matter).