Determination of a hydrofoil for the propulsion system of the 2000 University of California, San Diego human-powered submarine

UCSD students are building a human powered submarine to compete against other schools and attempt to break the International Human Powered Vehicle Association (IHPVA) and World Record in July 2000. This year´s submarine team has built a propulsion mechanism to drive a single oscillating horizontal foil through the water, very similar to how a mammal swims, to compete in the non-propeller division. In this experiment, a water tunnel was used to compare the lift to drag ratios of a straight and swept-back NACA 0012 symmetric foil with and without winglets. Although data taken only at two different water velocities is not completely conclusive, it was determined that a swept back wing with winglets is the configuration that provides the highest lift to drag ratio of 97.9 /spl plusmn/ 0.2 at an angle of attack of about 7 degrees. The swept wing without winglets showed the maximum lift to drag ratio of 170. It is clear fro relative values of the other wing configurations and other known data of the NACA 0012 that this ratio is abnormally high and is disregarded. Winglets decreased the lift to drag ratio for the straight wing at both velocities. At the lower velocity of 1.4 m/s, the straight wing without winglets had a higher ratio compared to that of the swept wing with winglets. However, at a higher velocity, the swept wing with winglets had a higher ratio. Disregarding the abnormally high ratio of the swept wing with no winglets, it is determined that this configuration provides the highest lift to drag ratio. Thus, implementing a tail with a swept back wing with winglets best propels the submarine to a very achievable IHPVA and world record.