Lag Pressure Talk

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You need to create PROPERLY DIRECTED SPEED.

How?

  1. A Good Backswing Pivot (not one of these un-athletic ones).
  2. A proper blending of Axis Tilt and torso rotation to help creat the force and DIRECT that force.
  3. Proper directing of the butt end of the club for the selected release.
  4. A SNAPPING of the Kinentic Chain from the ground up.
  5. Good Impact Alignmnets.
  6. A swivel that controls the clubface and the butt of the club rotation.
That'll do it. :)

Thanks, Brian. Could you clarify what you mean by "Butt of the club rotation"?
 
YouTube?

Butt Of The Club Rotation - Where the butt of the club points to from release point to the near-finish (past the swivel).

Brian, this would make a great YouTube video if you get a chance. You recently talked to me about this on the phone and talked me through a drill for this, I would love to see it on video (and am I sure many others would as well!)
 

lia41985

New member
http://www.tutelman.com/golfclubs/DesignNotes/swing4.php?ref=
The shaft is a string at impact. This one is true! This is not a myth at all, but a very reasonable metaphor. What it means is, "If you think you can affect ball flight by force you are exerting on the handle at impact, think again. You have no more control on the head during impact than if the club were on a string."

This is seriously counter-intuitive, so let's take a good look. We've already covered this from the point of view of frequency and time. The time constant of the shaft is orders of magnitude longer than the half millisecond of impact. But now we're ready to look at the forces involved rather than the more abstract time considerations.

* Clamp a shaft horizontally by its butt, and hang a one-pound weight from the tip. How much did the tip deflect when you added the weight? Even if you used a stiff shaft, the deflection was close to half an inch. So the shaft deflects at least an inch for every 2 pounds.
* Now, how much force does the head exert on the ball during impact? We figured it out in this section, and it's about 2000 pounds.
* So how much would the shaft have to deflect for the force it exerts to make a significant difference in what happens to the ball. Well, a one percent change in force is just about at the threshold of a detectable change in performance. That is, if the force change is less than one percent, any difference in the result is going to be too small to notice and very difficult to even measure. One percent of 2000 pounds is 20 pounds. If one pound bends the shaft a half inch, it will take ten inches of shaft bend to exert a force of 20 pounds. So the shaft would have to bend ten inches during impact to make a detectable difference in the ball flight. You know that's not going to happen.

Bottom line: The shaft won't exert any usable force on the head during impact. If your strength and weight don't get the job done while the clubhead is accelerating toward the ball, anything you do at impact won't have any more effect than if the shaft were a string.
 
Good Impact Alignments

Is this a reference to the Wedges?


You need to create PROPERLY DIRECTED SPEED.

How?

  1. A Good Backswing Pivot (not one of these un-athletic ones).
  2. A proper blending of Axis Tilt and torso rotation to help creat the force and DIRECT that force.
  3. Proper directing of the butt end of the club for the selected release.
  4. A SNAPPING of the Kinentic Chain from the ground up.
  5. Good Impact Alignmnets.
  6. A swivel that controls the clubface and the butt of the club rotation.
That'll do it. :)
 
Re-read what Jim wrote in his post. He swung harder with the stiffer shaft because he didn't have to time the kick of the whippier shaft--this made him subconsciously swing slower. You've confused cause and effect.

Or the stiffer shaft allow him to swing faster and release the kick? If the shaft is too flexible, perhaps it bends and kept the bend throughout the swing, thus never releasing the stored tensile force.
 

Brian Manzella

Administrator
What is funny....

par·a·digm (pār'ə-dīm', -dĭm') n.
A set of assumptions, concepts, values, and practices that constitutes a way of viewing reality for the community that shares them, especially in an intellectual discipline.

I think is it funny how paradigm busting is very tough for some folks.

"The clubhead acts as it is disconnected from the shaft."

Just deal with it—I did. I KNEW there was a problem with the heavy hit. So I adjusted in about a day on the lesson tee, and with my game in a few months.

I now know why I played as well as I did, pre-MASH. :)
 
Mandrin (and maybe Brian), explain this:

"The scratch golfer was superior in coordinating his alpha torque so to release the maximum stored strain energy in the shaft at impact. This timing is important since the unflexing of the shaft can contribute to the club head velocity."

"Shaft flexibility plays a part in generating club head velocity. The straightening of the shaft continues to accelerate the club head through impact even after the work by the wrist on the club is done. Approximately half of the shaft stored strain energy is released by impact and converted to higher club head velocities."

quoted from: http://www.jssm.org/vol4/n4/17/v4n4-17text.php

As previously concluded by Brian and confirmed by Mandrin, I thought the shaft is merely a timing mechanism which affects the impact alignments (such as the clubface and clubhead) of the golfer.
 
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Brian Manzella

Administrator
Great Question...Leo!

According to Mandrin, the shaft is just a timing mechanism.

I can live with that.

But, it sure seems like the UNLOADING of the shaft would add to the speed. Which is one reason I surmised that you would play with the stiffest shaft you could bend—and keep up with the UNbending.

Whatever the science says, I can adapt and teach around.

This winter, myself, and Manzella Academy Intructors Mike Jacobs and Damon Lucas are going on a little science tour....maybe we'll get to see Mandrin as well.
 
"The scratch golfer was superior in coordinating his alpha torque so to release the maximum stored strain energy in the shaft at impact. This timing is important since the unflexing of the shaft can contribute to the club head velocity."

"Shaft flexibility plays a part in generating club head velocity. The straightening of the shaft continues to accelerate the club head through impact even after the work by the wrist on the club is done. Approximately half of the shaft stored strain energy is released by impact and converted to higher club head velocities."

quoted from: http://www.jssm.org/vol4/n4/17/v4n4-17text.php

As previously concluded by Brian and confirmed by Mandrin, I thought the shaft is merely a timing mechanism which affects the impact alignments (such as the clubface and clubhead) of the golfer.
tongzilla,

Below is my critique of this paper by Nesbit posted about a year ago.

Nesbit/Serrano use three translational joints and three revolute joints to drive their club model. These are rigid elements. The golfer’s hands however are not rigid and interface the grip with soft biomechanical tissues. That makes a huge difference.

Put a driver in a vice and notice how remarkable long it will remain vibrating. Now put the club in the hands of someone instructed to keep a reasonable tight grip and try to oscillate the club. No way. Very simple demonstration and convincing proof.

The interface with the hands constitutes a substantial over damping of the oscillatory features of the golf shaft. One can also discuss this in terms of mechanical interface impedance between hands and shaft as being very soft.

All the sales hype about loading the shaft and it whipping/kicking forward, the frequency matching of shafts, it is all based on the behavior of a shaft as if being clamped in a vice. There is just only small problem – in a golf swing it is not.

Nesbit/Serrano mention the clubhead to return to its undeflected position near impact. Golf club experts/photographic evidence however will show that the shaft bends forward at impact. Not due to a forward kicking of the shaft but due to an inertial torque caused by the centrifugal force acting through the offset center of mass of the clubhead.

In short, an overdamped mechanical oscillatory sytem can’t be loaded with strain energy to be released as kinetic energy. However, let’s consider, just for arguments sake, that the approach and conclusion about the golf club by Nesbit/Serrano are correct. However they do mention:

The amount of strain energy absorbed and then released during the down swing is a very small percentage of the work transferred to the club.”

Hence, for all practical purposes, their very sophisticated shaft bending modeling can be considered to be a bit of an academic exercise, likely done for completeness and since their very sophisticated commercial modeling software package readily allowed it.

References:

Nesbit S, ‘A Three Dimensional Kinematic and Kinetic Study of the Golf Swing’.
JSSM-2005,Vol. 4, Issue 4, 499-519

Nesbit S and Serrano M, ‘Work and Power Analysis of the Golf Swing’.
JSSM-2005,Vol. 4, Issue 4, 520-533
 
The story goes on...

tongzilla,

Below is my critique of this paper by Nesbit posted about a year ago.

Nesbit/Serrano use three translational joints and three revolute joints to drive their club model. These are rigid elements. The golfer’s hands however are not rigid and interface the grip with soft biomechanical tissues. That makes a huge difference.

Put a driver in a vice and notice how remarkable long it will remain vibrating. Now put the club in the hands of someone instructed to keep a reasonable tight grip and try to oscillate the club. No way. Very simple demonstration and convincing proof.

The interface with the hands constitutes a substantial over damping of the oscillatory features of the golf shaft. One can also discuss this in terms of mechanical interface impedance between hands and shaft as being very soft.

All the sales hype about loading the shaft and it whipping/kicking forward, the frequency matching of shafts, it is all based on the behavior of a shaft as if being clamped in a vice. There is just only small problem – in a golf swing it is not.

Nesbit/Serrano mention the clubhead to return to its undeflected position near impact. Golf club experts/photographic evidence however will show that the shaft bends forward at impact. Not due to a forward kicking of the shaft but due to an inertial torque caused by the centrifugal force acting through the offset center of mass of the clubhead.

In short, an overdamped mechanical oscillatory sytem can’t be loaded with strain energy to be released as kinetic energy. However, let’s consider, just for arguments sake, that the approach and conclusion about the golf club by Nesbit/Serrano are correct. However they do mention:

The amount of strain energy absorbed and then released during the down swing is a very small percentage of the work transferred to the club.”

Hence, for all practical purposes, their very sophisticated shaft bending modeling can be considered to be a bit of an academic exercise, likely done for completeness and since their very sophisticated commercial modeling software package readily allowed it.

References:

Nesbit S, ‘A Three Dimensional Kinematic and Kinetic Study of the Golf Swing’.
JSSM-2005,Vol. 4, Issue 4, 499-519

Nesbit S and Serrano M, ‘Work and Power Analysis of the Golf Swing’.
JSSM-2005,Vol. 4, Issue 4, 520-533

Ok, I get how the hands overdampen the oscillatory system.

But the fact is that the shaft goes from bending backwards to bending forwards. You and I both agree with that. Ok, the shaft becomes forward bending due to the inertial torque caused by the centrifugal force acting through the offset center of mass of the clubhead, not because of the unbending itself. But so what? Shouldn't this change in direction of bend of the clubshaft cause an increase in clubhead speed, regardless of the dampening caused of the hands? I asked a similar question earlier this thread. Still waiting for your answer. ;)
 
Ok, I get how the hands overdampen the oscillatory system.

But the fact is that the shaft goes from bending backwards to bending forwards. You and I both agree with that. Ok, the shaft becomes forward bending due to the inertial torque caused by the centrifugal force acting through the offset center of mass of the clubhead, not because of the unbending itself. But so what? Shouldn't this change in direction of bend of the clubshaft cause an increase in clubhead speed, regardless of the dampening caused of the hands? I asked a similar question earlier this thread. Still waiting for your answer. ;)

tongzilla,

It is all too frequent that people use references as if that is all there is to it to prove or disprove their point. :mad: However, it seems clearly from your reaction that you accept my critique. ;) A scientific article as published is not the final say, it can definitely be wrong. :rolleyes:

With regard to your question, I might eventually, from the time history of the centrifugal force during the down swing, try to come up with a fairly accurate estimate - it will be a very small contribution - but in the mean time have a go at it yourself. :p

As a ballpark figure approach assume that the forward bending starts half way in the downswing. Let’s further assume that the forward bending results in an additional motion of about one inch for the clubhead of a driver, etc., et... :confused:
 
I know Wishon generally discounts the forward bending as adding anything significant to the clubhead speed. But, maybe another way to estimate the effect is to look at some old True Temper Shaft lab profiles. I'm not sure if it's used much any more, but TT had some shafts with strain gauges that were used to measure bending in the lag/lead and toe up/down direction during the swing. Here's an example

http://www.shaftlab.com/shaftlab/profile.html

Anyways, taking the lag/lead from this graph and even picking the max slope off the curve right before impact (this is probably an overestimate as usually in these profiles the clubhead actually reaches maximum lead before impact and flattens out or even decreases), say 1.5" bend forward in about 0.02 sec you get less than 5mph.(Edited - I had an incorrect decimal point on my original post:eek:. Anyway, 5 mph is probably on the high side of what's achievable, and for most swings much less).

Jay
 
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