Nope
It is NOT based on PAP being 6 3/4"/90° from your track.
Actually everything comes from degrees. 0-45-90 these are constant points. Distance calculation is made based on these.
That's why I wrote:
360degrees = 27 inches
45degrees = 3-3/8
6-3/4 is based on 3-3/8 being 45degrees from track, the leverage position. If you go 3-3/8 to reach 45 degrees, you go two times of it to reach 90 degrees
Think about a football. If you throw it with lying horizontally, 0 degrees angle from your palm directly (which will be 90 degrees angle to the direction that can be named as your track) it will go smooth and stable, spinning faster around its axis. If you throw it 90 degrees angle in relation to your palm (it rotates parallel to its axis, which can be measured 0) it will still go smooth but with less rotations. In both cases, since its axis is stable, it will not try to migrate anywhere. Now think about throwing it in 45 degrees..
45 degrees is the breakeven point. The more you get closer to each side more stable position you get. This is a physical fact.
PAP calculation is based on this fact. As I've written previously, it is sphere dynamics and I do not know enough physics to prove it to you with formulas..
Please check the diagrams in
http://www.bowling-tr.com/yazilar/bn-yazilar06.htmlUnfortunately it's not in English but pictures may help..
Why don't you find a college professor or mail some of the manufacturers?
I'd really like to hear their answers.
My best regards,
Burak