Fin - Controlling Motion

Controlling Motion

Once motion has been established, the motion itself can be controlled with the use of other fins.

The dorsal fin of a white shark contain dermal fibers that work "like riggings that stabilize a ship's mast", and stiffen dynamically as the shark swims faster to control roll and yaw.

Boats control direction (yaw) with fin-like rudders, and roll with stabiliser fins and fin-like keels. Airplanes achieve similar results with small fins that change the shape of their wings and tail fins.

A fin keel limits roll and sideways drift Ship stabilising fins reduce roll Ailerons control roll Elevators control pitch The rudder controls yaw

Stabilising fins are used as fletching on arrows and some darts, and at the rear of some bombs, missiles, rockets, and self-propelled torpedoes. These are typically planar and shaped like small wings, although grid fins are sometimes used.

Tail fins on a dart Asymmetric stabilising fins impart spin to this Soviet artillery rocket Conventional "planar" fins on a RIM-7 Sea Sparrow missile