Stability, the Three Axes and Coordinated Flight

An airplane rotates about three axes that all pass through the center of gravity: the longitudinal axis (roll, controlled by the ailerons), the lateral axis (pitch, controlled by the elevator), and the vertical axis (yaw, controlled by the rudder). Stability describes how the airplane responds when disturbed. Positive static stability is the initial tendency to return to the original condition, and positive dynamic stability means the resulting oscillations dampen out. Longitudinal stability depends heavily on center-of-gravity location: a forward CG is more stable but heavier on the elevator, while an aft CG reduces stability and can become dangerous. When you roll into a turn, the outside wing’s down-aileron produces more lift and more induced drag, yawing the nose away from the turn — this is adverse yaw. Applying rudder in the direction of the turn cancels it and keeps the flight coordinated.