Alan M. Nathan University of Illinois a-nathan@uiuc.edu Bat Performance and the NCAA Certification Protocol Does Aluminum Outperform Wood? Presentation made to the ASTM Subcommittee on Bats and Balls May 23, 2007 Alan M. Nathan University of Illinois a-nathan@uiuc.edu

REMINDER: Three parameters determine batted ball speed (BBS) in the field BBS = (BESR-0.5)vpitch+(BESR+0.5)vbat measure BESR in the lab define “standard field conditions” --vpitch --vbat (depends on MOI) use these to predict BBS in the field

Relation between swing speed and MOI aluminum wood

The NCAA Bat Certification Process Each bat is characterized by two regulated numbers: BESR: performance metric for fixed bat speed MOI: metric related to field bat speed Together, these determine BBS Higher BESR, higher MOI  same BBS higher BBS MOI BESR same BBS Same BESR, lower MOI  Higher BBS lower BBS Same MOI, lower BESR  Lower BBS

Example: 34” Bats 102 mph MOI limit max vf BESR limit 97 mph typical wood All bats below horizontal line and to right of vertical line are allowed

Conclusion The NCAA certification protocol limits field performance of non-wood bats Under “standard” conditions--- Wood = 97 mph Non-wood < 102 mph Difference < 5 mph, or about 5%

Does aluminum outperform wood? Summary: The NCAA certification protocol limits field performance of non-wood bats Does aluminum outperform wood? YES, by about 5% the 5% is an estimate based on the current state of the science left unregulated, aluminum would outperform wood by a significantly greater margin