HIGHLY SKEWED PROPELLERS

Theoretical and experimental data are presented that show the advantages and disadvantages of highly skewed propellers compared with conventional propellers. The advantages, in general, are reduction in unsteady bearing forces and moments, reduction in unsteady pressure forces, and increased cavitation inception speeds. These advantages are shown to be achieved without an adverse effect on the ahead efficiency and with only a minor decrease in backing efficiency. However, care must be used in the selection of skew to insure that the potential benefits are realized. Although the strength characteristics of highly skewed propellers are considerably more complicated than for conventional propellers, it is shown that there is no problem in assuring the strength integrity of the highly skewed type. To aid in the design of these propellers, correction factors for camber, ideal angle due to loading, and ideal angle due to thickness are presented for a limited series.