Control surface and actuator design for a low drag, laminar flow AUV

The design process for the control surfaces and actuators of the long distance AUV DOLPHIN (UK "Autosub" project) is described. The main design criteria are low drag, reliability, robustness and energy-efficiency. The aerodynamic characteristics of four NACA foil sections and various stabiliser/moveable fin geometries are compared, in order to reach the final design, which incorporates a NACA 66-009 wing section with a partial span trailing edge flap. The actuator is located in a wing-tip pod, which also houses the sensors for oceanographic data logging. Preliminary analysis of wind tunnel tests on a full-scale model of the control surfaces confirms that the lift force required to achieve the specified manoeuvrability for DOLPHIN is easily generated. Measured drag data is lower than expected and this requires further analysis.