Propulsion system performance enhancements on REMUS AUVs

This paper details recent efforts on drag reduction, vehicle shape and propulsion system modifications, and propeller design for the REMUS class of autonomous underwater vehicles (AUV). Drag reduction was accomplished by tow-tank measurements of an existing design to itemize the sources of drag. The vehicle shape and main propulsion system were modified to use magnetic torque transfer through a seawater collar to eliminate a rotating shaft seal. Propeller design efforts consisted first of a trade-off analysis of blade number, RPM, vehicle speed and blade shape to determine an optimum design and then refinement of that design for production version. The combined effect of these efforts resulted in a four fold reduction in propulsion power at the same speed of the previous design, and an increase in maximum achievable speed by almost a factor of two. These propulsion system performance improvements combined with recent changes in energy capacity for the vehicle result in a total per mission range of 120 km at 1.5 m/s for an endurance of 20 hours.