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Post by gmbtempe on Jan 30, 2013 11:31:28 GMT -5
I saw this post on Twitter from teacher Andrew Rice
Did you know that a strike a half an inch off center with a driver can be enough to tilt the Spin Axis up to 20 degrees!
He is a big Trackman user.
My question though is 20 degrees a lot? What does 20 degrees do to the ball?
When you get the path and face angle, how does Trackman know where you struck the ball? How do you know, without measuring impact on every shot, where you impacted it and how do you factor that into learning with Trackman?
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Post by wesleywillis on Jan 30, 2013 12:29:39 GMT -5
Point your finger downrange. Now point your finger 20 degrees to the left. Is that a lot?
Face to path is a general way to get an idea if the ball is being struck off center. Face open to path and a ball that has the spin axis tilted left is more than likely a toe shot.
Trackman does not just say 'Impact: Heel' like some of those simulators. The person at the helm must be able to interpret the numbers. Most pros who have used it enough themselves will know.
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Post by jeffy on Jan 30, 2013 12:40:03 GMT -5
I saw this post on Twitter from teacher Andrew Rice Did you know that a strike a half an inch off center with a driver can be enough to tilt the Spin Axis up to 20 degrees!He is a big Trackman user. My question though is 20 degrees a lot? What does 20 degrees do to the ball? When you get the path and face angle, how does Trackman know where you struck the ball? How do you know, without measuring impact on every shot, where you impacted it and how do you factor that into learning with Trackman?Excellent questions. I assume Andrew is referring to the influence of bulge on the actual clubface angle at impact. If you know the radius of the bulge on your driver, simple trigonometry will tell you how much a toe-side hit "opens" the clubface compared to center-impact, or how much a heel-side strike "closes" the face angle compared to center-impact. Obviously, a more "open" or "closed" face will add spin axis tilt. But, rather than speak in terms of spin axis tilt, which no one is really familiar with, why not just look at the number of degrees of face angle that are involved? You'll recall that at the Reserach-a-thon we sprayed the clubface with foot powder before each shot, then took a picture of the clubface post-impact. Here is one of your driver (BTW, this is your drive that landed smack on the target line, at least according to Trackman, the best we recorded!):  Using ProAnalyst imaging software, it is easy to precisely estimate how far from the center of the clubface contact was made. ProAnalyst uses the ruler to calibrate pixels into into centimeters, then, by setting the "origin" in the clubface's geometric center, can tell us how much towards the toe impact was made as well as how high on the face. Then, using the measured bulge and roll, we can calculate in Excel how much more "open" impact was and how much more loft was "added" compared to center impact. Here are your results:  For that particular drive, which was coded GB - 6 - .1R, contact was 0.84 inches towards the toe and 0.55 inches high on the face. As a result, that impact location was almost 4 degrees more open than center impact, and added 2.64 degrees of loft. Now, how does Trackman "know" the impact location? Well, it doesn't. It uses collision physics to "back into" the likely face angle AT POINT OF IMPACT. Based on the observed clubhead path and the initial ball flight, the Trackman software estimates what face angle relative to the path would produce the observed initial ball flight. Importantly, the actual spin axis tilt is measured, so off-setting gear effect is reflected there. As a result of gear effect, an open face-to-path relationship that produces a slice with center impact might, on a toe-hit, produce hook spin axis tilt, as happened with this drive. Here are the Trackman numbers: Path: 1.6 degrees (in-to-out) Face angle: 3.4 degrees (open) Face-to-path: 1.8 degrees (open) Spin axis tilt: -3.4 degrees (hook spin) As I mentioned, that ball landed dead on target. By looking at the displayed path, face angle and spin axis numbers, experienced Trackman users can make pretty good guesses about impact location. What this means for you is that, whenever you use Trackman, apply to the clubface spray powder (DON"T use Dr. Scholl's: it comes out too thick; buy the cheap stuff) or dry erase markers like are used on white boards, and, after enough experience, eventually you'll be able to deduce impact location simply from the displayed numbers. |
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Post by gmbtempe on Jan 30, 2013 12:47:44 GMT -5
Thats pretty dang neat....the off center numbers were in feet if I remember?
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Post by gmbtempe on Jan 30, 2013 12:49:01 GMT -5
Point your finger downrange. Now point your finger 20 degrees to the left. Is that a lot? Face to path is a general way to get an idea if the ball is being struck off center. Face open to path and a ball that has the spin axis tilted left is more than likely a toe shot. Trackman does not just say 'Impact: Heel' like some of those simulators. The person at the helm must be able to interpret the numbers. Most pros who have used it enough themselves will know. I am not sure its directly proportional though, 20 degrees and you would be almost off the range, yet you can see below I had one struck alomst an inch off yet it was a perfect shot. |
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Post by jeffy on Jan 30, 2013 13:01:49 GMT -5
Point your finger downrange. Now point your finger 20 degrees to the left. Is that a lot? Face to path is a general way to get an idea if the ball is being struck off center. Face open to path and a ball that has the spin axis tilted left is more than likely a toe shot. Trackman does not just say 'Impact: Heel' like some of those simulators. The person at the helm must be able to interpret the numbers. Most pros who have used it enough themselves will know. That's because of the gear effect from the toe-side hit. Andrew is recklessly ignoring the simultaneous, offsetting influence of gear effect in his tweet. Gear effect is precisely why bulge is built into drivers in the first place. If a driver existed where a half-inch mishit actually created 20 degrees of axis tilt, no one would ever buy it. That kind of "information" from Andrew can do more harm than good. |
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Post by jeffy on Jan 30, 2013 13:02:28 GMT -5
Thats pretty dang neat.... the off center numbers were in feet if I remember?Correct. |
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Post by teeace on Jan 30, 2013 13:06:34 GMT -5
Great work Jeffy with this. Thanks.
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Post by cloran on Jan 30, 2013 13:16:48 GMT -5
Thats pretty dang neat.... the off center numbers were in feet if I remember?Correct. Was there a net at 99R?  |
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Post by gmbtempe on Jan 30, 2013 13:17:37 GMT -5
I am not sure its directly proportional though, 20 degrees and you would be almost off the range, yet you can see below I had one struck alomst an inch off yet it was a perfect shot. That's because of the gear effect from the toe-side hit. Andrew is recklessly ignoring the simultaneous, offsetting influence of gear effect in his tweet. Gear effect is precisely why bulge is built into drivers in the first place. If a driver existed where a half-inch mishit actually created 20 degrees of axis tilt, no one would ever buy it. That kind of "information" from Andrew can do more harm than good. Thanks, When I first bought the FT-9 driver it was my first driver in several years and I commented to a few people that this thing feels like it self corrects, inside heal, outside toe, dang thing seems to find the fairway. I thought the only difference has to be better engineering but kinda thought to myself "yea right" but maybe that is indeed the case. I know I need a new one based on our testing, I only hit yours 15 yards further with the same shaft. |
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Post by gmbtempe on Jan 30, 2013 13:18:25 GMT -5
Was there a net at 99R? thats only 33 yards.........I actually was hitting it pretty straight, fought pulls and a few pushes when I was really trying to get it out there. Jeffy challenged me to do 99R again, I obliged. |
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Post by gmbtempe on Jan 30, 2013 13:20:44 GMT -5
I twittered Rice back with some questions, doubt I get an answer.
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Post by jeffy on Jan 30, 2013 14:07:56 GMT -5
That's because of the gear effect from the toe-side hit. Andrew is recklessly ignoring the simultaneous, offsetting influence of gear effect in his tweet. Gear effect is precisely why bulge is built into drivers in the first place. If a driver existed where a half-inch mishit actually created 20 degrees of axis tilt, no one would ever buy it. That kind of "information" from Andrew can do more harm than good. Thanks, When I first bought the FT-9 driver it was my first driver in several years and I commented to a few people that this thing feels like it self corrects, inside heal, outside toe, dang thing seems to find the fairway. I thought the only difference has to be better engineering but kinda thought to myself "yea right" but maybe that is indeed the case. I know I need a new one based on our testing, I only hit yours 15 yards further with the same shaft. For a little history on the subject, a formula for calculating the correct amount of "bulge" to counter-act gear effect was patented in 1946 by Spalding. Below is a link to the patent application. Be sure to click the link to the PDFs of the hand drawn exhibits (next to "View Patent Images:"). www.freepatentsonline.com/2395837.html |
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Post by gmbtempe on Jan 30, 2013 14:12:40 GMT -5
Thats pretty sweet, wonder who owns the patents, and do manufacturers have to pay a royalty to that patent owner?
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Post by birlyshirly on Jan 30, 2013 14:26:03 GMT -5
Not any more. Anything filed in 1946 is long expired.
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