Better Hitting Through Science
IF HITTING RECORDS ARE falling like fly balls in a blinding glare this year, wait till the sluggers notice the latest findings from sports scientists. Doctoring the bat, they say, might give hitters an edge -- and they're not talking about something so patently illegal as corking. It turns out that roughing up a bat by pressing dimples into it can decrease the air resistance it meets by 60 percent. That increases swing speed by 3 to 5 percent. ""The bat whips around faster and the ball rockets off it,'' says inventor Jeffrey Di Tullio, an aeronautics instructor at the Massachusetts Institute of Technology who patented the dimpled bat earlier this year. ""That could give you 10 more feet on a well-hit ball'' -- the difference between a long out and a home run.
The dimpled bat works on the same principle as a golf ball. When something moves through the atmosphere, a thin layer of air sticks to it. This air pushes against the swung bat, slowing it down with a drag force. Dimples are the Pac-Men of drag. The roughness of the surface causes turbulence around the bat, mixing the stationary ""boundary layer'' with faster-moving layers farther away. Rather than piling up in front, air slips to the back of the bat. This slipstream effect cuts drag.
Little League, semipro and farm teams have expressed interest in Di Tullio's bat, so MIT is looking for a manufacturer. As for the majors, league rules call for ""a smooth, rounded stick.'' The Rules Committee has not offered a formal opinion on dimples, but hitters might achieve almost the same effect by nicking their bats.
They might also look into weather modification. ""If it's hot or humid, the density of the air decreases,'' says engineer Robert Watts of Tulane University. That cuts the drag on a hit ball. Other things being equal, a 10 percent decrease in air density (90 degrees instead of 50 degrees, 100 percent humidity instead of 0) would allow a ball to fly 5 percent farther, Watt calculates. That's 20 feet on a 400-foot fly.