A Comparison Between a Simple Drag Formula and Experimental Drag Data for Bodies of Revolution

Abstract : A simplified drag formula to predict the drag of a small number of axisymmetric forms is systematically applied to seven series of model forms comprising nearly fifty bodies. Calculations of form (or residual) drag are compared to available experimental data in order to determine the usefulness of the method for predictive purposes. The formula is shown to exhibit very little sensitivity to changes in most body parameters such as the length-of-stern to diameter ratio, nose and tail radii parameters, and the prismatic coefficient. For some parameters, such as length to diameter ratio, the length of bow section to diameter ratio, however, the formula is sometimes able to discriminate bodies having high values of form drag. It is concluded that the simple drag formula may not be reliably used for estimating the relative form drags of bodies of revolution.