Hi Dave,
It's a good diagram and I see how it can come into play as an aiming compensation method and it's arguable whether this is the best way to go. But it sure is interesting that most of the world's best potters swipe on the type of shots where gearing english has advantages and how so many swipe when attempting heavy side english and masse' type shots.
While filming VEPS, Tom Ross and I had many heated "discussions" about the swoop stroke. Tom was a major swooper and a very good player. Tom and I did many tests and experiments to try to determine if a swoop stroke could apply more spin to the CB (to help settle our "differences of opinion"). Before all of these discussions, tests, and experiments, Tom was a firm believer that the swoop stroke could apply more spin to the CB (seemingly defying the normal miscue limit). After the discussions, tests, and experiments, he was no longer a believer; although, he still used the swoop stroke because that is what he always did, and it worked well for him. He preferred aiming closer to center ball, where it is easier to visualize the exact aim for the shot, and he preferred applying BHE (to compensate for squirt) during the stroke instead of before. It is what came naturally to him, and it is the way he learned to apply english from watching his "old-timer" mentors who did it that way.
Again, I think the main benefit of a swoop stroke is that it allows one to apply the BHE squirt correction during the stroke instead of before the stroke. BHE before the stroke can be awkward, uncomfortable and unnatural to some people. Some, while aiming and aligning a shot, don't like seeing the cue pointing in a different direction than they want the CB to head. Also, some people don't like to change stance and cue alignment after being down on a shot, which is what occurs with a pre-stroke BHE pviot.
I've highlighted what I'll call the swipe component which I think may increase the spin of the CB in that direction, even for a zero offset hit, i.e swipe to center CB.
...
Obviously we can't get that type of pure swipe effect on a CB with a swiping action, but it seems reasonable to me that we could get a part of this effect.
Colin,
I agree that if the swooping speed is significant compared to the forward stroking speed, more spin can be created for a given tip contact point. As Jal's diagram clearly shows, the swooping motion changes the velocity vector of the tip creating a different effective tip offset from center (and if this effective tip offset is beyond the miscue limit, a miscue will occur, with or without swoop). However, this velocity vector change would also change the direction the CB heads (as if the cue were aimed in a different initial direction, along the new velocity vector, with a straight stroke). Obviously, this would not be a good effect when trying to aim a shot with sidespin.
I propose the following test:
Setup a straight shot aimed at a ball frozen to a rail like in Diagram 3 of "
HAPS - Part II: BHE and FHE" (BD, December, 2014). Then, using fixed CB and bridge positions, aim to hit the CB directly into the frozen ball with near maximum english (on the horizontal centerline of the CB) with the same speed and with the cue at the same near-level elevation and tip position for each shot. Try multiple attempts using both a straight stroke with pre-stroke BHE, and a swoop stroke (starting with a center-ball alignment and using BHE during the stroke instead). Faster speed is preferable to minimize swerve effects and to help reduce possible variability from one shot to the next. Although, if using a video camera, the shot speeds can be checked later (by looking at the time between the hits of the CB and OB), and shots that aren't close enough to the same speed can be thrown out. If this is being done, any consistent shot speed can be used
If desired, adjust the bridge length so the pre-stroke BHE aim adjustment is as good as possible in compensating for net CB deflection (the combined effects of squirt and swerve), resulting in a square hit on the frozen ball.
Does the CB head in the same direction with both the BHE and swoop strokes? If not, make adjustments in the aims so the CB heads in the same direction for both stroke types. Then remove the frozen ball, and hit the same strokes into the rail. Does the CB come off the cushion at different angles due to spin differences between the different stroke types?
Honestly, I haven't done a set of experiments this complete or careful before, but I intend to. I will post a video online when I can find the time to do the tests and video editing, but I also encourage the swoopers out there to give it a try and report back what they find. I think the test and results could help resolve many of the apparent disagreements in this thread and help improve everybody's understanding of the effects involved.
Catch you later,
Dave
