BASE-VENTED PROPELLER,

This report describes the design and testing of a propeller with base-vented blades. A semi ellipse with a parallel afterbody was chosen as a cross section for the blades. This shape, with a trailing cavity, has a lower cavitation index than a blade section of the same thickness ratio that converges to a thin trailing edge. The blade shape has a large area moment for increased strength and a relatively large leading-edge radius, which reduces the tendency for a low pressure region to develop at the leading edge attributable to an off-design angle of attack. The low cavitation index allows the blade to op erate at moderate depths at high forward velocity and rpm. Author