Suuntaperäsin

Suuntaperäsin, also known as a rudder, is a control surface used to steer a vessel or aircraft. In nautical applications, it is a flat, typically hinged blade or plate mounted at the stern of a ship or boat, below the waterline. Its primary function is to control the direction of travel by deflecting the flow of water. When the helm is turned, the suuntaperäsin pivots, causing water to push against one side of it, thereby turning the stern in the opposite direction. This change in direction causes the entire vessel to maneuver. The size and design of a suuntaperäsin vary greatly depending on the size and type of vessel.

In aviation, a suuntaperäsin refers to the vertical control surface located at the rear of an aircraft, part of the tail assembly. It works in conjunction with the ailerons and elevators to provide three-axis control. The suuntaperäsin is hinged to the fin and is controlled by the pilot's rudder pedals. When deflected, it creates a sideways force on the tail, causing the aircraft to yaw, which is a rotation around its vertical axis. This yawing motion is crucial for coordinated turns and for counteracting adverse yaw. Like its nautical counterpart, the design of an aircraft suuntaperäsin is influenced by the aircraft's aerodynamics and performance requirements.