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Aerodynamics of a Curveball: The Sikorsky Lift Data



In the 1940's and 50's, the United States was engaged in a national debate on whether the curve in baseball was an optical illusion. During this debate, Igor I. Sikorsky and Ralph Lightfoot investigated the lift force produced by a baseball spinning from zero to 1200 rpm in a wind-tunnel at free-stream velocities between 80 and 110 miles per hour (35.8 and 49.2 m/s). A brief note about the findings were later published by Joseph Drury (1953) reporting Sikorsky had determined that a four-seam pitch could curve three time more than a two-seam pitch. However, the more substantive supporting experimental data was never published and over the years appeared to have been lost. The original Sikorsky/Lightfoot data set was recently uncovered and is presented here. It is compared to more recent aerodynamic lift data for golf and baseballs with excellent correlation. The data also shows that seam orientation (i.e. surface roughness) has a large influence on lateral deviation in a high velocity pitch.

KEYWORDS: Baseball, Golf, Aerodynamics, Lift Coefficients

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Last changed April 16, 2000

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