TW Reverse Engineering tool put to work on AK90/K90

[corners]

TW University has a handy new reverse engineering/customization tool:

http://twu.tennis-warehouse.com/learning_center/customizationReverse.html

I've been curious about the Asian K90 (AK90) since I picked up a US K90, which is a bit much for me, being a little guy. However, although the AK90 has the same sweet feel of the K90, it doesn't swing quite the same, and I've been trying to decide if that's a good or a bad thing.

Other posters have speculated that the AK90 is just a K90 minus 20 grams in the handle, which would make sense, given it's 1cm more head heavy. But, adding virtual weight back onto the AK90 using the above tool leads me to believe that the AK90 is simply a depolarized version of the K90:

AK90:

Weight: 335 grams
Swingweight: ~320
Balance: 32.5 grams

Add: 4 grams at 12 o'clock (26.5 inches)
Add: 16 grams at .6" ( about half an inch from the butt)

You get:

Weight: 355 grams
Swingweight: 334
Balance: 31.5 cm

This is a K90. You can see that weight was removed from the poles of the K90 to create the AK90. I don't see any other way to get the K90 specs from the AK90 by adding only 20 grams - if you add weight further from the poles you'd have to add more than 20 grams to get the same swingweight and balance.

The AK90 is a depolarized K90.

This would make sense, as the AK90 has about the same stiffness and feel of the K90. It's known that Wilson's braided graphite/kevlar box beam construction is heavy by nature - there's a limit to how light they can make the frames. To make a lighter version of Fed's racquet they had to take off the head and tail weights they incorporated into the K90 layup for him (as well as a bit more weight that's been in the handle since the ol' 85).

Posters have suggested that the polarized weighting of the K90 could be responsible for its easier swinging qualities when compared to previous Tour 90s. The polarization of the frame could be responsible for the consensus view of K90 users on this board that this racquet is simply badass.

In light of this, as well as the supposed general virtues of racquet polarization - namely: high power to weight ratio, spin friendly, high swingspeed to swingweight ratio - does the AK90 being a depolarized K90 mesh with your experience in swinging and playing with these frames?

And do you think that polarized frames are superior to depolarized ones?

 

[corners]

Turning the Pro Staff 85 into a K90

Using the same tool it appears that to turn a Pro Staff 85 into a K90 you would have to (aside from making the head a bit bigger) polarize it. Which is more difficult since the Pro Staff and K90 weigh about the same:

Wilson Pro Staff 85 (from USRSA)
Weight: 354 g.
Swingweight: 323
Balance: 31.75 cm

Add 4g. at 12 o'clock (26.5")
Add 8g. at .3" (in the butt)
Remove 11g. from 10" (center of throat)

You get:

Weight: 355 g.
Swingweight: 333
Balance: 31.5 cm

^Pretty much a K90

You can fiddle around with where you remove the weight - toward the lower hoop works too, as does the top of the handle. But the bottom line appears to be that Wilson removed approximately 10g. from the middle of the Pro Staff 85 and moved it to 12 o'clock and the butt as the Pro Staff series evolved into the K90.

Knowing already that an AK90 is a depolarized K90, the other tool (http://twu.tennis-warehouse.com/cgi-bin/customize.cgi) could be used to add lead to the handle or throat of the AK90 (and a smidgeon on the PWSs) to get an approximation of a Pro Staff 90.

The simplest way to do it would be to add 19 grams at 8.7" from the butt - the site of the infamous bulge on the KPS 88. John Cauthen would be proud.

You could also try to turn a K90 into a Pro Staff 90 (for some reason) by removing the bumper, adding a gram or two at 3&9, removing the leather grip and adding 13 grams at the top of the handle. You'd have to be ok to play with an overgrip on the bare pallet however.

 

[zidane339]

Interesting read, good work!