What is the function of the rudder in an aircraft?

The primary function of the rudder in an aircraft is to control yaw, which refers to the left and right movement of the aircraft's nose around its vertical axis. The rudder is a movable surface located on the vertical stabilizer (tail fin) of the aircraft and is crucial for stabilizing the aircraft's direction during flight. When the pilot pedals in one direction, the rudder deflects, allowing for correction in the aircraft's heading and improving overall maneuverability.

Additionally, the rudder plays an essential role in coordinating turns in conjunction with the ailerons, as it counteracts adverse yaw that can occur when a plane turns. This helps maintain a smooth and stable flight path, enhancing control and safety during various flight maneuvers.

The other options describe functions that are not directly related to the rudder's purpose. For instance, the control of lift and drag is primarily managed by the wings and other control surfaces, engine thrust is managed by the aircraft engines, and the risk of tailspin is influenced by multiple factors, including the aerodynamics of the aircraft and the pilot's inputs. Thus, the rudder's role is specifically tied to controlling yaw and stabilizing the aircraft during flight.