There is a lot to observe in these High Speed Photos.
Notice the Clubface Closing from Impact to Separation?
If the Ball rolled up the face, because of friction, then we should see the ball rise during the compression stage. But the Ball lifts during rebound.
Daryl,
It looks like there is some rolling of the ball on the face during the compression stage. You can see it in the driver and 3 iron photos. Look closely at the logo and ball # and you'll see a slight upward tilting of the ball during compression. Its very, very slight but shows the ball does change its polar axis during impact. Its not just a direct rebound off the clubface from a decending clubhead blow.
This action might explain why sharper grooves help keep the ball in its original axis thereby increasing spin.
Then again, these photos might depict impact after lowpoint.
Just guessing.
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It looks like there is some rolling of the ball on the face during the compression stage. You can see it in the driver and 3 iron photos. Look closely at the logo and ball # and you'll see a slight upward tilting of the ball during compression. Its very, very slight but shows the ball does change its polar axis during impact. Its not just a direct rebound off the clubface from a decending clubhead blow.
This action might explain why sharper grooves help keep the ball in its original axis thereby increasing spin.
Then again, these photos might depict impact after lowpoint.
Just guessing.
great observation.
The impacts are before Low Point.
I can see the name tilting as you describe. I couldn't tell whether that's from rolling or straight forward deformation. But the spin (rolling) is much more obvious as the ball leaves the face of the club.
Tonight I'll include photos of a Wedge and 7 iron.
Tom Wishon said he did some super high speed research a couple of years back. To my knowledge none of the photographs have been released publicly. His conclusions were that the ball does move slightly up the face as well as deform. His iron and wedge designs since appear to have more bite to them via more grippy faces as well as the groove design work.
Interesting. I've been reading about this lately and it seems the agreement is under normal dry conditions, that groove design isn't significant.
I can see how roughing the face would add friction, but I'm not convinced that Roll-up is the complete answer.
I would think you don't have to have roll up per se, just 'grip' to transfer energy into spin. You might only be using one or two grooves on any given shot for that grip, but I'd have to say grooves matter!
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