Experimental determination of baseball spin and lift

The aim of this study was to develop a new method for the determination of lift on spinning baseballs. Inertial trajectories of (a) ball surface markers during the first metre of flight and (b) the centre of mass trajectory near home-plate were measured in a pitch using high-speed video. A theoretical model was developed, incorporating aerodynamic Magnus-Robins lift, drag and cross forces, which predicts the centre of mass and marker trajectories. Parameters including initial conditions and aerodynamic coefficients were estimated iteratively by minimizing the error between predicted and measured trajectories. We compare the resulting lift coefficients and spin parameter values with those of previous studies. Lift on four-seam pitches can be as much as three times that of two-seam pitches, although this disparity is reduced for spin parameters greater than 0.4.

[1]  Tait.  XXI.— On the Path of a Rotating Spherical Projectile , 1895 .

[2]  Alexander J. Smits,et al.  A new aerodynamic model of a golf ball in flight , 2002 .

[3]  Mont Hubbard,et al.  Identification of Release Conditions and Aerodynamic Forces in Pitched-Baseball Trajectories , 2001 .

[4]  J. Neter,et al.  Applied linear statistical models : regression, analysis of variance, and experimental designs , 1974 .

[5]  L. W. Alaways.  Aerodynamics of the curve-ball : an investigation of the effects of angular velocity on baseball trajectories , 1998 .

[6]  M Hubbard,et al.  Rapid and accurate estimation of release conditions in the javelin throw. , 1989, Journal of biomechanics.

[7]  Lyman J. Briggs,et al.  Effect of Spin and Speed on the Lateral Deflection (Curve) of a Baseball; and the Magnus Effect for Smooth Spheres , 1959 .

[8]  J. W. Maccoll.  Aerodynamics of a Spinning Sphere , 1928, The Journal of the Royal Aeronautical Society.

[9]  Russell Fish,et al.  Keep your eye on the ball , 1989, SIFN.

[10]  P. Bearman,et al.  Golf Ball Aerodynamics , 1976 .

[11]  Carl Warren Selin.  An Analysis of the Aerodynamics of Pitched Baseballs , 1959 .

[12]  Robert G. Watts,et al.  The lateral force on a spinning sphere: Aerodynamics of a curveball , 1987 .

[13]  H. M. Barkla,et al.  The Magnus or Robins effect on rotating spheres , 1971, Journal of Fluid Mechanics.

[14]  佐竹 元一郎,et al.  Applied Linear Statistical Models--Regression,Analysis of Variance,and Experimental Designs 3rd ed./John Neter et al.(1990) , 1991 .

[15]  J. M. Davies,et al.  The Aerodynamics of Golf Balls , 1949 .