202 バックスピン時のディンプル球の空力特性(G05-2 物体周りの流れ,G05 流体工学)  [in Japanese] 202 Aerodynamic Coefficients of a Dimpled Sphere in Back-Spin  [in Japanese]

A golf ball is pitted with about 300-500 of dimples on the surface, and their effects of boundary layer control to lengthen the range greatly are well-known. The present paper reports the experimental data measured using a wind tunnel concerning the effect of drag reduction of dimpled spheres in back-spin and the effect of lift production as the synagetic of both dimples and back-spin. We obtained the aerodynamic feature of dimpled spheres in back-spin that the inclinations of drag polars change counterclockwise with a decrease in the depth of dimples. We also found first that the efficiency of lift production is approximately 35% within the limits of our experiments.