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Post by dubiousgolfer on Aug 10, 2020 8:18:35 GMT -5
Hi DG, Thanks for explaining. First, are you able to make sense of the excel chart's findings of "horizontal to impact" vs. "impact velocity" where shaft angular acceleration is so much proportionately greater in JB's case, yet impact velocity is no where near proportionately greater? Your explanation reminded me of the use of a socket wrench to loosen a bolt. Consider the type of socket wrench with a hinge that allows the torsion bar segment of the wrench to be both in line (parallel to) with the bolt and at an angle to the bolt (in the event that there is an object in the way of the torsion bar). Given the same force applied to the bar, it is easier to loosen the bolt if the bar is parallel to the bolt. As applied to the golf swing, I think your idea has merit, except that the alignment of shaft to shoulder may only be relevant through some specific and unidentified distance prior to impact. In my own swing, to get to my desired top-of-swing position, I think of a plane "through my right shoulder" even though the shaft probably ends up slightly above the plane of the shoulders. From that position, it's easiest for me to apply turning force that transfers to the club. S Hi S The impact velocity of the clubhead is probably related to the net force magnitude and direction across the handle of the clubhead (in front of the clubs COM) from P6-P7. Even though there is greater angular acceleration shown in JB , there is very little time to exert that greater acceleration from P6-P7 , so I doubt there will be that much difference in their clubhead speed. It's very similar to that positive hand couple torque from say P5.5-P6. Some golfers might wish to time a little helping kick-start to PA#2 release but if its being applied in about 2 msecs , how much greater clubhead speed is that really going to achieve? Actually , on a slightly different matter , that little 'kick start' reminded me of Robert Grober's video below regarding 'Resonance' (something I brought up in another forum over 6 years ago). DG
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Post by imperfectgolfer on Aug 10, 2020 10:26:07 GMT -5
DG,
You wrote-: "I have been looking at some swing images of both players and I have a theory that JB Holmes more vertical shoulder plane (because of his greater right side lateral flexion) is more in line with his left arm plane and that is optimising the MOF force from P6-P7.
If you look at the shoulder plane plane of Rory , it seems to be moving on a flatter plane compared to his left arm plane , therefore there will be a smaller component of the MOF in line with the left arm plane compared to JB."
The capture images where you drew yellow lines only show that RM's shoulders turn more horizontally than JBH's shoulders post-impact and I cannot see any significant difference pre-impact. Also, I think that one should only be looking at the lead shoulder, and not the trailing shoulder, to determine whether there is a difference in their lead shoulder's motional path between P6 => P7 and I cannot see any significant difference.
It would be useful to see if there are any differences in the inverse dynamic calculations of the forces/torques for those two pro golfers to see if there is any difference that could account for the fact that JBH's clubshaft's angular velocity does not decrease pre-impact (as seen in RM's 3D graph). It would seem that "something" is causing the slope of RM's clubhead speed graph to flatten pre-impact and that flattening phenomenon is not seen in JBH's graph. In the absence of that force/torque data, I cannot rationally provide an explanation.
Jeff.
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Post by imperfectgolfer on Aug 10, 2020 10:49:40 GMT -5
These 3D graphs have called into question my "beliefs" about the relationship of clubhead speed at impact and the speed of release of PA#4. I previously believed that clubhead speed at impact would highly correlate with the speed of release of PA#4 (speed of the release of the left arm), but I am wrong. For example, note that Rickie Fowler has a very high left arm speed at its peak (compared to JB Holmes), but his peak clubhead speed at impact is less.
Also, note that all the pro golfers (except for Ernie Els and JB Holmes) show that there is a slight slowing of their speed of clubhead acceleration (= slope of the graph) before impact. I wonder why it happens? Jeff.
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Post by dubiousgolfer on Aug 10, 2020 12:03:04 GMT -5
Dr Mann I'm more inclined to believe JB shoulder plane (especially his lead shoulder ) is more aligned with his left arm plane from P6-P7 I've overlaid P6 and P7 images below and one can clearly see that Rory's left upper arm is no longer visible at P7 . Its moved more horizontally than JB's upper arm which is still visible at P7. Also , although it might be irrelevant, Rory's right shoulder shows an even more horizontal movement from P6- P7 than JB . Look at how much the upper right arm has moved towards ball-target line compared to JB. It's more difficult to see Rory's arm plane compared to his lead shoulder plane but it seems as if its becoming more vertical DG
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Post by imperfectgolfer on Aug 10, 2020 13:37:31 GMT -5
DG,
One cannot see Rory's left upper arm at P7 because his shoulders are more open at P7. I personally do not think that it affects the MoF being generated between P6 and P7.
Jeff.
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Post by dubiousgolfer on Aug 10, 2020 17:29:23 GMT -5
Dr Mann
You are probably correct . I did the same image comparison with Ricky Fowler and Ernie Els and couldn't see any correlation between shoulder plane and arm plane.
Maybe we are looking at this from the wrong perspective inasmuch that Ricky Fowler's PA#4 release is such that it might become uncontrollable and too fast for him to control an optimal release of PA#3.
The Choi graphs from previous posts show that the 9 pro golfers were actually pulling their trail hand away from target approaching impact. Could that explain why there is a levelling off clubhead angular velocity approaching impact but that Ernie Els and JB Holmes are exceptions?
DG
PS. There is also negative torque in both hands approaching impact in those Choi graphs.
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Post by dubiousgolfer on Aug 10, 2020 20:31:17 GMT -5
Just looking at these Choi graphs again , I did notice that there was quite a pulling up force along the shaft axis (towards the butt end of the club) by the right hand into impact (see graph G). It does seem that the right hand has quite a significant involvement in the Net Force that causes the MOF across the club from P6-P7. Wonder if that provides further clues as to why PA#4 release by the left arm cannot explain alone the angular acceleration of the club. DG
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Post by syllogist on Aug 11, 2020 10:00:35 GMT -5
Hi DG,
I don't believe that the release of PA#4 is the key to "horizontal to impact" speed, or "release speed." In fact, it's probably counterproductive if one tries to activate it with muscular force. With maximum adduction of the left arm and maximum chest rotation to create the top of swing position, release speed is predicated on: 1) wrist cock angle 2) rotational velocity of the chest 3) "continued adduction" of the left arm during the phase of rotation acceleration of the chest.
Point 3 above implies that one does not seek to increase left arm speed by a muscular effort to move toward abduction. In a state of adduction, which not does mean that the left arm must be maximally adducted, during chest rotation one is able to create the "tightest arc" around which the club can be rotated. You have already theorized that the right elbow "connection" maneuver creates a "short right arm" around which the club can rotate. What I am describing is a similar concept except that it is based on left arm adduction during chest rotation.
Point 3 explains the phenomenon of the "narrow" hand path (when the golfer is seen in a face-on view). In other words, if the golfer were to keep his back to the target while swinging his arms down plane, the golfer would create the "widest" hand path possible around which the club would rotate - a no no.
Simply put, the technique that accelerates the CLUBHEAD the fastest from the top to about halfway between vertical and horizontal will best predict clubhead speed at impact.
S
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Post by dubiousgolfer on Aug 11, 2020 17:56:32 GMT -5
Hi DG, Thanks for explaining. First, are you able to make sense of the excel chart's findings of "horizontal to impact" vs. "impact velocity" where shaft angular acceleration is so much proportionately greater in JB's case, yet impact velocity is no where near proportionately greater? Your explanation reminded me of the use of a socket wrench to loosen a bolt. Consider the type of socket wrench with a hinge that allows the torsion bar segment of the wrench to be both in line (parallel to) with the bolt and at an angle to the bolt (in the event that there is an object in the way of the torsion bar). Given the same force applied to the bar, it is easier to loosen the bolt if the bar is parallel to the bolt. As applied to the golf swing, I think your idea has merit, except that the alignment of shaft to shoulder may only be relevant through some specific and unidentified distance prior to impact. In my own swing, to get to my desired top-of-swing position, I think of a plane "through my right shoulder" even though the shaft probably ends up slightly above the plane of the shoulders. From that position, it's easiest for me to apply turning force that transfers to the club. S I had to edit my post again - the physics/maths was wrong - still some unanswered questions (but probably irrelevant anyhow). DG
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Post by dubiousgolfer on Aug 11, 2020 22:17:47 GMT -5
Hi DG, I don't believe that the release of PA#4 is the key to "horizontal to impact" speed, or "release speed." In fact, it's probably counterproductive if one tries to activate it with muscular force. With maximum adduction of the left arm and maximum chest rotation to create the top of swing position, release speed is predicated on: 1) wrist cock angle 2) rotational velocity of the chest 3) "continued adduction" of the left arm during the phase of rotation acceleration of the chest. Point 3 above implies that one does not seek to increase left arm speed by a muscular effort to move toward abduction. In a state of adduction, which not does mean that the left arm must be maximally adducted, during chest rotation one is able to create the "tightest arc" around which the club can be rotated. You have already theorized that the right elbow "connection" maneuver creates a "short right arm" around which the club can rotate. What I am describing is a similar concept except that it is based on left arm adduction during chest rotation. Point 3 explains the phenomenon of the "narrow" hand path (when the golfer is seen in a face-on view). In other words, if the golfer were to keep his back to the target while swinging his arms down plane, the golfer would create the "widest" hand path possible around which the club would rotate - a no no. Simply put, the technique that accelerates the CLUBHEAD the fastest from the top to about halfway between vertical and horizontal will best predict clubhead speed at impact. S Hi S Looking again at this video below (for a major winner driver swing) , its not that straightforward. There is still a lot of linear force along the mid-hand point path from P6-P7 . If you check the video around 06:28 the 'Linear Force' is max around 350 N around P6.2 (and that's just a component of the 'Net Force' being applied on the club which shows 412 N). It reduces to about 104 N at impact (23 lbs force) while the 'Net force' across the club maxes to about 464N (104 lbs force) at P6.7 decreasing to about 442N at impact. The total amount of work done by that 'Linear Force' is 239 Joules . Further , one then has the 'Hand Couple' doing positive angular work 58 Joules until just past P6 (see 12:10) , then it does 'negative' work (ie. its impeding the angular acceleration of the club) from P6-P7 with a total work contribution of about 24 Joules. SMK says there is a close relationship between the 'linear & angular' work done on the club versus clubhead speed. The total work is 239 +24 = 263 Joules 'Linear Force' work is responsible for 90% 'relationship' contribution to clubhead speed , while 'Hand Couple' contributes 10% of that perceived 'relationship', but the 'Linear Force' component of the 'Net Force' is still high from P6-P7 which suggests that there is still active release of PA#4 happening. And if one looks at the previous Choi Force graphs 'B' and 'F' , it seems that the left arm is moving more actively along the linear hand path than the right hand. I don't know for certain what would be the generator of the active left hand contribution to that 'Linear Force' from P6-P7, but I suspect its a mix of the upper body pivot and the left shoulder girdle muscles. SMK has not yet provided any videos on the importance of hand path shape that could maximise the MOF caused by the 'Net Force' across the club . Apparently the MOF is an impulse that can create club angular acceleration but is not included in the 'work-energy' vs 'clubhead speed' relationship he was investigating. If you look at the video the 'Net Force' can be a lot greater than the 'Linear force' from P6-P7 , so it still confuses me why he doesn't include work done by a certain share of the 'Net Force' (that might be acting independently of the 'Linear Force') to contribute to the MOF. DG PS. One also needs to look at the Choi graphs for the significant trail hand 'force' component up the axis of the shaft (towards the butt end) into impact . There is a peak 'z' axis force (graph G) probably as the hands 'turn the corner' around P5.5 -P6 but it's still retained at a slightly lower figure into impact . This could be a reactionary pull to keep the club from slipping out of the hands due its 'dynamic weight' or it could be an active pull to try and change the hand path. I would have thought the former might involve a 'passive' right arm while the latter a more active one with most of the force more in line with the shaft than a linear force (the Choi graph shows that the the right hand is actually pulling on the grip in the -y axis direction , away from target approaching impact - graph F). Maybe this points to a few reasons for a bent left arm at impact (for some of the PGA pros) where the forces via the right arm/hand might be more active than the left arm/hand in changing the hand path 'upwards' nearing impact . If the left shoulder socket cannot move 'up/back' quickly enough to accommodate that change in hand path , maybe the left arm needs to bend. Alternatively , if the forces via the right and left arm/hand are too passive and not enough to change the hand path , maybe the left arm needs to bend. It could just be an instinctive move by the golfer to either prevent hitting a fat shot or increasing the 'Net Force MOF' by a more acute change in hand path , or maybe both.
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Post by syllogist on Aug 12, 2020 7:52:04 GMT -5
Hi DG, ________________________________________________________________________________________________________________________________ "Linear Force' work is responsible for 90% 'relationship' contribution to clubhead speed , while 'Hand Couple' contributes 10% of that perceived 'relationship', but the 'Linear Force' component of the 'Net Force' is still high from P6-P7 which suggests that there is still active release of PA#4 happening. And if one looks at the previous Choi Force graphs 'B' and 'F' , it seems that the left arm is moving more actively along the linear hand path than the right hand." ________________________________________________________________________________________________________________________________
My thoughts:
The angular component in the 90/10 relationship assumes a standard full backswing (involving arm adduction and chest turn) and a standard, full wristcock. So we think of the angular component as being "fixed" in this relationship. Therefore, in order to generate more clubhead speed, initial chest rotational velocity must increase. It may be reasonable to assume that the angular component percentage would increase as the force used for chest rotation decreases. If so, the only means to increase clubhead speed is to rotate faster in lieu of greater backswing rotation.
If one considers that left arm adduction is largely maintained to shaft horizontal and that active abduction is not performed, then one can still attribute the high linear force component at P6 to chest rotation (left arm is connected to shoulder which is part of the torso). In addition, decreasing right elbow bend beyond shaft horizontal results in "hand travel" along the path, which affects P4.
Also in terms of whether of not active P4 separation occurs, consider that joints moving in space, e.g., left arm off left shoulder, right forearm off elbow, hand off wrist, make it more difficult (effort involved) to move a segment attached to a joint, and it only becomes easier the slower that the joint is traveling through space.
S
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Post by dubiousgolfer on Aug 12, 2020 8:24:17 GMT -5
Hi S
Not sure what you meant by " It may be reasonable to assume that the angular component percentage would increase as the force used for chest rotation decreases" . The hand couple is responsible for the angular work and I can easily imagine that upper torso pivot can influence both the 'linear force work' and , indirectly , the 'hand couple angular work'.
What do you mean by P4 separation?
When I look at that SMK video , there is still a 'linear hand force'(23 lbs force) happening at impact while I suspect the right hand is 'dragging' behind rather than actively moving targetwards. I suspect the linear force along the hand path is more likely due to the left arm while the right arm/hand is assisting in a more 'up ' direction in line with the shaft.
DG
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Post by syllogist on Aug 12, 2020 9:37:26 GMT -5
Hi DG,
With regard to the angular component percentage, my point is that changes in linear force alone likely do not result in a 90%/10% relationship between the linear and angular component. My understanding of a "net hand couple" is that such is what "moves" the club and can involve both hand travel along path as well as hand travel "around" the wrists. I am not sure how one would change the net force of the couple given a certain linear force (through chest rotation) except via a longer backswing or change in wrist angle.
(P4 separation = left arm movement toward abduction)
I can't comment about whether your suspicion is correct about the right arm/hand and left arm/hand (dragging vs. moving targetward) in the tour pro swing except that I can say that both hands and arms are moving targetward considering that their connection is to the shoulders which are both rotating in roughly the same direction. However, I suppose that the dragging/moving targetward can be true if one tries to add additional force by "swinging" the left arm using shoulder muscles and keeping the right arm passive.
If the individual hand force graphs are correct, it's still quite a puzzle to figure out exactly what causes the different results for each hand.
S
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Post by dubiousgolfer on Aug 12, 2020 10:05:12 GMT -5
Hi S
The reason for the left/right hand 'drag' effect is caused by the club releasing so fast (via 'inertial' forces - such as the 'Net Force MOF') that the wrist joints (which are not frictionless like PingMan and Iron Byron) cannot keep up with the angular velocity of the club.
DG
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Post by syllogist on Aug 12, 2020 10:53:50 GMT -5
Hi DG,
Leave out wrist motion during release for now. I would contend that both arms drag during release (and slow as a result) as the momentum of the clubhead travels in one direction while the arms travel in the opposite direction? The point made about the club "releasing so fast" (emphasis on "so fast") has been used to emphasize the futility in trying to actively force the release of the wrists. So, I was hypothesizing how the only the right hand could drag without the left hand dragging.
S
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