Development of an Auxiliary Propulsion Module for an Autonomous Underwater Glider

A low-power propeller-based propulsion module has been developed to augment the buoyancy engine of a 200 m Slocum electric glider. This device is introduced to allow new behaviours such as horizontal flight and faster overall speeds to expand the existing operational envelope of underwater gliders. The design of the system is optimized for use at the typical horizontal glider speed of 0.3 m/s. Before integration into the glider the stand-alone propulsion module has been tested in a small flume tank to verify the systems performance. The validity of a previously published hydrodynamic model of the glider at zero angle of attack was verified by conducting drag measurements at various flow velocities at full scale in a larger flume tank. Self-propulsion tests were also performed to establish the performance of the glider with the new propulsion module in the larger flume tank and in the university tow tank. The results from these tests show that the new propulsion module is able to match the performance of the conventional glider for full depth profiles and to exceed it for limited depth profiles.