Comparative Performance of Stock and Design Propellers Derived from Propulsion Experiments,
DAVID W TAYLOR NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER BETHESDA MD
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It has been the practice at DTNSRDC and other towing tanks to use the results of experiments with stock propellers fitted to a hull model to make preliminary predictions of the powering performance of the hull, and to provide propulsion coefficients to be used in the propeller design process. At times selected stock propulsion coefficients have been used with the propeller efficiency of the design propeller to provide a more precise estimate of the powering performance of the hull when fitted with the design propeller. The purpose of this report has been to investigate problems which have arisen in the selection and use of stock propellers with the objectives of comparing the propulsion coefficients derived from experiments with stock and design propellers and recommending changes to existing practices if practicable. Data from experiments with 19 hull forms representing destroyers, frigates, and various naval auxiliaries were retrieved from the records at DTNSRDC. Some of the hulls had more than one design propellers fitted, so it is possible in certain samples to compare the stock propeller performance to several design propellers and that of one design propeller to another. This investigation is successful only in identifying what are cosidered to be major contributions to the variations in performance. Differences in diameter between stock and design propellers appear to be the major contributor to poor predictions of performance.