More Paul Wood Research on the Impact Interval....

[Brian Manzella]

I have communicated back and forth with Dr. Wood in the past week regarding some information passed along to us by Todd Dugan from someone who supposedly use to worked for TaylorMade in "the 90's."

Here is brief summarization of what Paul had to say:

ex-TM guy: "...the clubface rotates about 1.9* while the ball is on the clubface..."

Paul Wood: "I just did a quick check of some high speed video files of our own and also did some cross referencing with a really good study in England using high speed cameras where they focused exactly on the impact itself.

On average we're seeing something like 0.5 degrees of closing of the face during the impact. This is backed up by the English study too."

​

ex-TM guy: "...a Dynamic Loft during impact of 8* less than the static loft of the club was an often-recurring number..."

Paul Wood: "...we typically see dynamic loft of much more than the static loft on the driver. If you look at a snapshot of Bubba Watson at impact the dynamic loft is in the teens while he is using a 7 degree driver. He's an extreme example of course, but most players do a smaller version of that."

​

ex-TM guy: "...because the clubface is rotating during impact, the toe of the clubface is moving 15-20 mph faster than the heel. This compresses the outer part of the ball more than the inner part and results in a 6* "hook torque" applied to the ball. In other words, if Iron Byron hits a ball with the clubface holding square to the arc during collision, then the ball will fly without curve. But, if the clubface is rotating, like Tour pros do it, and the clubface is square to the arc during collision, then the ball will react as if the clubface were 6* closed. A radical finding indeed!"

Paul Wood: "...we observe the face to be fairly square at impact for our player test subjects. It might be a tiny bit open before impact and a tiny bit closed after impact but not 6 degrees by any means."


​

Paul will be speaking at a PGA Clubfitters conference in December in San Antonio. Sounds like a good place to learn from one of the best!

 

[dbl]

Wow! Hopefully TM has upgraded their knowledge and technical abilities to match the current/correct stuff.

 

[(.Y.)]

Would be interesting to try and reproduce some of the findings of the TM guy.. That one with an open then significantly closing clubface through impact causing draw spin interests me. Given that most weekend golfers likely have extremes of clubface rotation over what paul woods may have observed in his experiments, seem like we dont have any more insight on that one yet?

 

[natep]

I think the theory of the 6 degree hook torque can be easily debunked by anyone with a Trackman. According to the TM guy's logic a shot that was zeroed out, path and face, would produce a draw because the right side of the ball got compressed more by the rotating clubface. I haven't heard of anyone reporting this phenomenon.

 

[Todd Dugan]

I have communicated back and forth with Dr. Wood in the past week regarding some information passed along to us by Todd Dugan from someone who supposedly use to worked for TaylorMade in "the 90's."

Here is brief summarization of what Paul had to say:

ex-TM guy: "...the clubface rotates about 1.9* while the ball is on the clubface..."

Paul Wood: "I just did a quick check of some high speed video files of our own and also did some cross referencing with a really good study in England using high speed cameras where they focused exactly on the impact itself.

On average we're seeing something like 0.5 degrees of closing of the face during the impact. This is backed up by the English study too."

​

ex-TM guy: "...a Dynamic Loft during impact of 8* less than the static loft of the club was an often-recurring number..."

Paul Wood: "...we typically see dynamic loft of much more than the static loft on the driver. If you look at a snapshot of Bubba Watson at impact the dynamic loft is in the teens while he is using a 7 degree driver. He's an extreme example of course, but most players do a smaller version of that."

​

ex-TM guy: "...because the clubface is rotating during impact, the toe of the clubface is moving 15-20 mph faster than the heel. This compresses the outer part of the ball more than the inner part and results in a 6* "hook torque" applied to the ball. In other words, if Iron Byron hits a ball with the clubface holding square to the arc during collision, then the ball will fly without curve. But, if the clubface is rotating, like Tour pros do it, and the clubface is square to the arc during collision, then the ball will react as if the clubface were 6* closed. A radical finding indeed!"

Paul Wood: "...we observe the face to be fairly square at impact for our player test subjects. It might be a tiny bit open before impact and a tiny bit closed after impact but not 6 degrees by any means."


​

Paul will be speaking at a PGA Clubfitters conference in December in San Antonio. Sounds like a good place to learn from one of the best!

In response to point #2....Static Loft vs. Dynamic Loft with the driver MAY be much different than with irons. No Tour pro's Dynamic Loft is MORE than the Static Loft with an iron....or fairway wood for that matter. Perhaps the -8*# is more accurate for impacts "off the deck".

Point #3...Nobody suggested that the clubface CLOSES 6* during impact, Dr. Wood. Just that the closing clubface during impact imparted a hook spin on the ball, the effect of which is equivalent to a 6* closed Clubface, even when the Clubface is square to the Path during impact. It doesn't seem as if Dr. Wood acknowledged that this particular phenomenon was being suggested. But since he indicated that the Clubface closes only .5* during impact, it doesn't seem as if he would give the notion any merit, either.

But this is why I didn't name my source. I didn't want him to get blindsided by some kind of "internet rebuttal". Frankly, the exchange has only shed more light on the subject and I appreciate the opportunity to hear anything Dr. Wood has to say on this subject. In the end, I just want the best scientific info available. I recognize that a leader in this field has directly refuted some of my source's findings. Thank you, Brian, for having what I relayed checked out.

Maybe I can make it out over to San Antonio next month for some impact study and a little BBQ brisket !

 

[Brian Manzella]

Would be interesting to try and reproduce some of the findings of the TM guy.. That one with an open then significantly closing clubface through impact causing draw spin interests me. Given that most weekend golfers likely have extremes of clubface rotation over what paul woods may have observed in his experiments, seem like we dont have any more insight on that one yet?

PING has tested 1000's of regular golfers.

So have I.

 

[SteveT]

Think about the consequences .... if there is a 6º 'hook torque' applied to a teed up golf ball because the driver toe is closing while the heel is retreating, that means you must somehow apply a slicing counter-spin to compensate for the horizontal torque spin applied to the ball upon Impact.

This means the toe is closing and the heel is opening while rotating around the vertical longitudinal gravitational axis, which defines the location of the 'sweet spot' axis on the driver face. IOW, the toe-side impact area is pushing the ball while the heel-side impact area is sucking the ball back sorta.

The assumption is that the ball is struck on the driver face sweet spot axis. If the ball is hit towards the toe, the 'hook torque' will slap the ball even harder and either pull the ball or apply more hook spin or both.

This means the ball spin axis is forever tilted because of the horizontal 'hook torque' applied upon Impact, and the only way to apply a counter-spin is to open the clubface for a D-plane compensation of the 'normal' face vector to the swing path vector.

How would one measure the amount of slicing counter-spin, and how would the compromised D-plane be affected?

 

[Wilson!]

If this guy is right, a driver face closing through impact would cause a fade and viceversa (assuming otherwise neutral D-Plane/swing path), due to gear effect. That seems to be the reason behind adjustable weight screws in some drivers.

 

[SteveT]

If this guy is right, a driver face closing through impact would cause a fade and viceversa (assuming otherwise neutral D-Plane/swing path), due to gear effect. That seems to be the reason behind adjustable weight screws in some drivers.

Are you suggesting that to compensate for driver head 'hook torque', one should attempt to hit the ball off the sweet spot and towards the toe??

Horizontal gear effect vanishes if you hit on the sweet spot.

 

[Wilson!]

Are you suggesting that to compensate for driver head 'hook torque', one should attempt to hit the ball off the sweet spot and towards the toe??

No, I guess hitting towards the toe would create more hook. Taylor Made, by placing the heavier screw closer to the hosel, means moving the sweet spot to the heel and causing a draw bias. Only a few grams are involved, so it won't compensate a serious case of slice.

Horizontal gear effect vanishes if you hit on the sweet spot.

Agreed. The screws move the sweetspot in order to create gear effect.

 

[Brian Manzella]

In other words....

That 6° "hook torque" is pure-d J-U-N-K.

 

[SteveT]

No, I guess hitting towards the toe would create more hook. Taylor Made, by placing the heavier screw closer to the hosel, means moving the sweet spot to the heel and causing a draw bias. Only a few grams are involved, so it won't compensate a serious case of slice.

Those weight inserts can't move the CofG enough, maybe a fraction of a millimeter, to affect the Sweet Spot. You can pull the CofG to the back of the driver head, but that usually requires quite a bit of added backweight.

I tried those TM drivers and didn't feel much of a difference .. but maybe it has an effect on the dynamic swingweight.

Agreed. The screws move the sweetspot in order to create gear effect.

Since the CofG isn't much affected by the nominal weight redistribution, the gear effect change may not be significant.

It's one thing for TM to make a performance claim to the market, but it's very different when they have to prove their performance claims.

 

[SteveT]

In other words....

That 6° "hook torque" is pure-d J-U-N-K.

I didn't say that ... YOU did ...

 

[Wilson!]

SteveT, yes, the movable screws weigh a few grams. Notwithstanding, I have an R7 and feel a certain rightist tendency when I place the heavier screw to the toe, while I usually hit the push draw I like when that screw is on the heel side.

That could well be a placebo effect, but I swear at least the sound and feeling are a bit different.

I played a practice round with a scratch who was trying to enter a local tour (I'm located in Argentina). He had a high swing speed. He insisted that my setup, heavy screw-to-heel side, should cause a fade. We discussed a bit until I lent him the R7. He announced a fade ... but got a draw to his surprise.

That was only one case, not enough for a scientific conclusion. Even very good players misshit from time to time, they can occasionally hit an anwanted fade or draw. But the incident made me think that the screw stuff worked at least for high speed swings, when not overrode by swing path and D-plane.

What do you think about this explanation by Dave Tutelman?:

All about Gear Effect

 

[billmckinneygolf]

The TM screws work. No doubt about it. And you can feel them on the first swing.