Design and fabrication of a collective and cyclic pitch propeller

Abstract

Autonomous underwater vehicle propulsion has been primarily driven by conventional thruster arrangements and control fins. The development of a collective and cyclic pitch propeller system provides a highly maneuverable alternative to these conventional designs. Therefore, a computer controlled and fully actuated collective and cyclic pitch propeller was designed and fabricated to fulfill this need. -- The new propeller was designed using a helicopter like linkage system. The swash plates mounted inside of the propeller housing, as opposed to propeller hub like a helicopter. Locating the linkages in the housing provided a more maintainable system of linkages, due to space limitations in the propeller hub. The swash plate was positioned using three ball screw electric actuators using absolute positioning feedback. The swash plate position was transmitted to the propeller hub by a set of four control rods, one for each blade. Four blades were chosen for the propeller to reduce pulsing of the propeller when operating in cyclic mode. -- Initial testing of the prototype demonstrates the propeller's potential ability to control the underwater vehicle at little or no forward speed. While operating in the 50% ahead, 100% to port condition, a thrust value of 26.7 N (6 lbf) with a turning moment of 18.9 Nm (168 in-lb) was measured. The turning moment generated at a forward speed of 1 .6 m/s was sufficient to turn the C-SCOUT vehicle in 38% of the present required turning circle using a conventional thruster and control fins.