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Old 09-27-2006, 05:58 AM   #25
Greg Raven
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Join Date: Feb 2004
Location: Apple Valley, CA
Posts: 618
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I have a spreadsheet I've been using for a couple of years now to help me match racquets. The results of my spreadsheet correspond with the on-line tool Crawford Lindsey developed for USRSA members at However, if I plug the same numbers into each of our spreadsheets, there are differences in the results.

Here is an example, starting with my spreadsheet:

Starting mass 331.50
Starting balance 32.20
Starting swing weight 310.00

COP 52.12
Recoil weight 147
Hitting weight @ COP 175

Added mass 0.00
Location 0.00

Added mass 0.81
Location 53.34

Added mass 3.19
Location 58.42

New mass 335.50
New balance 32.50
New swing weight 319
New COP 52.26
New recoil weight 149
New hitting weight 179

Note that I am calculating the Hitting weight at the COP.

When I plug these same numbers into your spreadsheet, I get these results:

Starting mass 331.50
Starting balance 32.20
Starting swing weight 310.00

Starting recoil weight 146.624
Starting hitting weight 0.789
Starting polarization index 0.442

Final mass 335.50
Final Balance 32.50
Final swing weight 319.00
Additional mass 1 0.81
Additional mass 2 3.19

Swing weight increase 9.00
Total added mass 4.00
Mass Location 57.362

Location of added mass 1 17.305
Location of added mass 2 67.534

Final recoil weight 149.153
Final hitting weight 0.837
Final Polarization Index 0.445

I haven't yet had the time to track down the reason(s) for the differences.
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