Aircraft Control Surfaces and Forces

Main Control Surfaces

• Purpose: Allow the pilot to rotate the aircraft in three dimensions.
• Effects of Controls:
  • Primary and secondary effects associated with each control surface.

Four Main Forces on an Aircraft

• Lift:
  • Generated by the wings.
  • Represented by a lift arrow.
• Weight:
  • Sum of the aircraft's mass.
  • Always points down towards the center of the Earth.
  • Represented by a weight arrow.
• Thrust:
  • Generated by the power plant.
  • Represented by a forward horizontal arrow.
• Drag:
  • Resistance opposing thrust.
  • Represented by an opposing horizontal arrow.

Control Surfaces and Their Effects

Ailerons

• Primary Effect: Roll
  • As the aircraft rolls, the lift force rolls with it.
  • Vertical component of lift decreases, causing the aircraft to slide down.
  • Secondary Effect: Yaw
    • Rudder exposed to side airflow, pushing tail left, resulting in yaw.

Rudder

• Primary Effect: Yaw
  • As the aircraft yaws, the outer wing moves forward and faster, creating more lift.
  • Secondary Effect: Roll
    • Resulting roll viewed from behind.

Stabilator

• Primary Effect: Pitch
  • Pitching down increases forward motion, airspeed increases, and altitude decreases.
  • Pitching up decreases airspeed.

Additional Effects of Increased Power

• Spiralling Slipstream:
  • Behind the propeller, enhances airflow volume.
  • Affects empennage, making stabilator and rudder more sensitive.
  • Wraps around fuselage, impacts rudder, inducing leftward yaw for clockwise rotating propeller.