Design of a flapping foil underwater vehicle

The design, construction and testing of a biomimetic flapping foil autonomous underwater vehicle is detailed. The project is a proof of concept for the use of flapping foils as the sole source of propulsion for an underwater vehicle. We intend to use the vehicle in several physical arrangements to compare the swimming performance of different shapes and foil arrangements. The vehicle was designed for maximum flexibility and scalability in terms of the number and placement of foils through the creation of self-contained modular actuators, each requiring only DC power and a connection to the vehicle Ethernet LAN. The current vehicle implementation consists of four actuators, each driving a single foil with a span of 0.40m and an average chord of 0.10m. The foils are paired port-starboard, with one pair at the bow and one at the stern. Each foil has a 180 degree range of motion about the roll (chordwise) axis and unrestricted motion about the pitch (spanwise) axis. The dimensions of the vehicle without the foils is approximately 2m x 0.5m x 0.5m. Results from disparate sets of tests have been gathered to demonstrate the suitability of flapping foils for the generation of thrust and force vectoring during cruising, of thrust at zero-speed, and the development of rapid transient forces with a single foil stroke. All of these are requirements for operation in dynamic environments which impose unpredictable transient forces on an underwater vehicle.