Effect of Bio-Inspired Control Fin Position on the Hydrodynamic Maneuverability and Stability Parameters of Unmanned Underwater Vehicles (UUVs)*

Current UUVs typically have control fins located near their aft end for making controllable turns. However, many bony fish, including tuna, have deployable fins located in front of their center of buoyancy (CoB). This allows them the ability to modulate their hydrodynamic response for both rapid turning maneuvers and level cruising, but the details of this hydrodynamic effect is not understood. To investigate this phenomena, a torpedo shaped vehicle was used as a model, and a pair of fins were added at different hull positions to investigate the effects of fin location on the horizontal plane hydrodynamics. The model was towed for angles of attack (AoA) between 30° and -30°, and force and moment data collected. It was found that based on the added fin location, the AoA where the horizontal plane moment crossed the zero axis shifted. From a design standpoint, this indicates that stall occurred later for control fins in front of the CoB, increasing the vehicle maneuverability. Overall, this study investigated the hydrodynamic reasoning for tuna control fin position. From a maneuverability perspective, adding deployable control fins away from the typical aft end configuration may be beneficial to a UUV’s maneuverability.