Williebetmore said:
J,
It could be that you are considering a different shot than the rest of us ....
I don't mean to ignore Black-Balled and Scott's challenges, but let me respond to them through you.
First of all, thanks for taking the time to lay it out so thoroughly. You've definitely established that we're talking about the same shot. And so I think we all agree that you need to get counter-clockwise spin on the OB to bring it back to the bottom right pocket after banking it off the upper long cushion.
Now, if someone knows how to make this shot with heavy left at some specific shot speed (such as yourself), far be it for me to suggest that it should be done some other way. My only contention is that you can get more counter-clockwise spin on the OB with no english or just a touch of it. One consequence would be that you could bank the OB a little higher up on the long cushion, or maybe have better success on slick cloth, where having the spin take on the cushion might be a problem. But I'm not arguing for any particular method, only the issue of what english (or lack of it) imparts the most spin on the OB.
The reason I think you'll get max spin with little or no english is that imparted spin and throw of the OB go hand-in-hand. The more throw, the more spin. This is well established and follows from the fact that the friction which throws the OB is the very same thing that causes it to spin.
Now it just happens to be that for a stun shot (or near stun shot) without any cueball sidespin, maximum throw occurs somewhere between 20 and 35 degrees, depending on shot speed and ball surface conditions, both of which affect the magnitude of the friction. For medium speed shots with normal balls, it's around 25-30 degrees. Given that the shot we're discussing is roughly 30 degrees, it follows that hitting it with stun and little or no english will impart maximum spin. Heavy left will actually reduce the spin because the magnitude of the frictional force is diminished due to increasing relative surface speed between the balls.
I was thinking of going into a long-winded explanation of what causes maximum throw/spin, but this post may be getting tedious already. Bob Jewett has some experimental results concerning throw here (item 24):
http://www.sfbilliards.com/misc.htm
And here is a theoretical treatment:
http://www.engr.colostate.edu/~dga/pool/technical_proofs/new/TP_A-14.pdf
The graph on page 10 is most relevant. The bottom of it is labeled with things like "RWx/v". These are spin/speed ratios. A value of zero (middle of the bottom axis) represents no english, while a value of -1 (left side of the axis) represents near maximum inside english, and a value of 1 (right side of the axis), near maximum outside english. The purple line is for a pure stun shot, the others for various amounts of added topspin.
If the above isn't your cup of tea, or you still think I'm wrong (which is always possible of course) I think a more intuitive explanation can be offered up.
Jim
