In his calculation of ball speed, he has three factors that are used to calculate ball speed - Vclubhead, M (mass of the clubhead) and m (mass of the ball).
That formula seems to imply that the clubhead has a constant velocity through impact. However, doesn't the clubhead continue to accelerate through impact as a result of the continuing release of power accumulators #1 and #3? It is my understanding that release of power accumulators #1 and #3 is only complete at the end of the followthrough (when both arms are fully straight and the leftarm-clubshaft is in a straight line alignment), and that they are still powering the golf club through impact (while the ball is in contact with the clubface). If correct, doesn't that "acceleration phenomenon" impart additional energy to the ball, that is not factored-in when David Tutelman uses that particular mathematical formula to calculate ball speed at the moment of ball-clubface separation?
There is really nothing that continued acceleration can contribute to ball speed over the half-millisecond impact interval.
Your reference draws heavily from Cochran & Stobbs. They also did a study where they created a club with a hinge in the shaft near the hosel so that there could be no force applied to the clubhead in the direction of travel by the shaft or anything connected to it. They found no experimentally significant difference between shots hit with a normal club and the hinged club. It's as though the clubhead is on a string at impact.
I realize that TGM teaches otherwise. But I believe that if you perceive impact in the TGM manner and execute the stroke according to that perception, you will enter impact with the best set of alignments and vectors, including high clubhead velocity.
Zin14 is probably right...the bottom line is to do what Homer Kelley wanted us to do....and argue about WHY it works later...that is just chapter 2....
There is really nothing that continued acceleration can contribute to ball speed over the half-millisecond impact interval.
Zin14
Intuitively that makes sense, but I still have nagging questions.
Driver manufacturers can and do build "spring effect" into the clubface in order to boost the rebound. That probably has nothing to do with this topic, but it highlights the importance of the impact interval on ball behavior.
The ball is hitting the clubface as hard as the clubhead is hitting the ball, so the clubhead slows down during and past impact. Is it possible to resist clubhead deceleration (mph)?
What about the long lever? With a locked flat left wrist at impact, you are bringing the entire primary lever (left arm and clubshaft) into impact with the massive rotor still pulling. This isn't something that is well duplicated on a simple swing machine with a flail hooked up to a clubshaft.
Do you have any data or experiments to defend the impact statement? I know there is a lot of heresay, but I've yet to see data that has been examined and approved by multiple recognized scientific sources in the golfing community. Would love to see it if you can share it.
Along those lines, I've yet to see any published materials disproving materials in Chapter 2, but there is also a lot heads nodding that much of the 40 year old material has been debunked. That may be true, but lets bring those scientific studies out in the open. I'm sure Homer would be happy to have more precise data added to what has been written.
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Bagger
1-H "Because of questions of all kinds, reams of additional detail must be made available - but separately, and probably endlessly." Homer Kelly
Gotta run soon so I have to be quick. I can address more fully later.
First, the Cochran & Stobbs snippet from Search for the Perfect Golf Swing is data on this subject. As I said, they installed a hinge on the shaft right above the hosel and hit balls with it to prove the point.
Spring effect is another subject--it works by allowing more deformation in the face, thus requiring less deformation in the ball. The face metal is more elastic than the ball, so less energy is lost.
Yes, if you can resist deceleration during impact you will produce higher ball speed. The problem is that you have no more leverage to apply force to the clubhead in this position. If impact occured maybe a foot after start-down from the top, this would be possible, but there would be no speed.
In the Detonum thread where Bucket posted all the swing sequences, look at all the pictures showing the shafts bending forward just before impact. The shafts are stressed the wrong way! There is a simple explanation for this and it has nothing to do with technique. But what it shows is that all the inertia and firmness of the wrist, left arm, shoulder, etc. is linked to the clubhead through the shaft and none of it can resist deceleration until the shaft is stressed the other way, by which time the ball is way outta there.
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