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Post by utahgolfer on Apr 1, 2020 18:55:08 GMT -5
As I understand it, forward shaft flex occurs between p6.5 and impact because the left arm begins to decelerate due to the left shoulder rotating more up and around versus toward the target. I assume the rate of left arm deceleration, the length of the club shaft, and the stiffness of the club shaft make a difference in the amount of forward shaft flex, but what is the influence of a drive-hold release?
A key to the drive-hold release is to keep the left arm moving at the same angular velocity of the club shaft from p7 to p7.5.
Here is Lydia Ko, at 2:22, demonstrating both a lot of forward shaft flex and a non-drive-hold release. Is it logical to assume she would have had less forward shaft flex just before and after p7, had she employed a drive-hold release?
Here is Charlie Hoffman, at 6:34 and 6:49, demonstrating a decent drive-hold release, using a driver. Would he have had more forward shaft flex had he flipped released, with less sustained left arm speed?
Here is Charlie Hoffman, from :32 to :60, swinging an iron, which I assume inherently demonstrates less forward shaft flex. But, does this superior drive-hold release decrease the degree of forward shaft flex that might be present?
UG
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Post by dubiousgolfer on Apr 1, 2020 20:31:03 GMT -5
Hi UG
I think forward shaft bend seems to occur maybe nearer to P6 according to Sasho MacKenzie vimeo videos.
With regards whether the intent to 'Drive-Hold' limits forward shaft bend just before impact, I would suspect 'Yes' because of 'TruTemper ShaftLab' research results that Dave Tutelman published on his website . Minimising the impedance of the hands on the proximal end of the club while the peripheral end 'swings out' might reduce the forward shaft bend.
DG
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Post by imperfectgolfer on Apr 2, 2020 9:50:20 GMT -5
UG,
You wrote-: "As I understand it, forward shaft flex occurs between p6.5 and impact because the left arm begins to decelerate due to the left shoulder rotating more up and around versus toward the target. I assume the rate of left arm deceleration, the length of the club shaft, and the stiffness of the club shaft make a difference in the amount of forward shaft flex, but what is the influence of a drive-hold release?"
I have a different perspective. I believe that forward shaft flex of the peripheral shaft in a pro golfer has nothing to do with left arm slowing in the later downswing and I believe that it is due to an efficient release of PA#2 that causes the peripheral shaft to travel faster than the proximal shaft after P5.5. I do not believe that a DH-hand release action will have any effect on this phenomenon, which happens in the pre-impact phase between P5.5 and impact.
I think that it is worthless trying to compare the degree of forward shaft lean seen in different swing videos because >90% of any visible forward shaft lean seen in a swing video is likely due to camera shutter artifacts (especially exaggerated in that Lydia Ko video).
Jeff.
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Post by imperfectgolfer on Apr 2, 2020 10:20:19 GMT -5
Here is Dana Dahlquist's review of Charley Hoffmann's golf swing.
Stop the video at the 8:08 minute time point when CH is at his P6 position. Note that Dana labels him as manifesting a punch elbow because his right elbow is positioned alongside his right shirt seam, but I believe that he is using a pitch elbow motion (note that his right forearm is very supinated and his right palm is under the club handle and it never gets partially on top of the club handle between P5.5 and impact).
Jeff.
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Post by utahgolfer on Apr 2, 2020 20:58:17 GMT -5
I am sure that the slowing of the left arm has something to do with forward shaft flex, since they happen simultaneously. But, it certainly could also be related to an efficient release of PA#2.
In any event, what matters is that the left arm continues to move with enough forward motion to promote a drive-hold release pattern as perfectly demonstrated by Milo Lines, so the club shaft doesn't pass the left arm until well past impact.
UG
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Post by imperfectgolfer on Apr 2, 2020 22:21:15 GMT -5
UG,
You wrote-: "I am sure that the slowing of the left arm has something to do with forward shaft flex, since they happen simultaneously. But, it certainly could also be related to an efficient release of PA#2."
First of all, just because two events happen at the same time does not imply a direct cause-and-effect relationship between two separate event-effects. Secondly, an efficient release of PA#2 will naturally cause the left arm to slow due to the COAM principle and due to the fact that the swing radius progressively increases when the club releases. So, the release of PA#2 can cause both left arm slowing and the peripheral clubshaft to bend forward. Another reason for left arm slowing after P5.5 is the fact that PA#4 has been maximally released between P5 and P5.5 and no further energy is inputted after P5.5 to prevent natural left arm slowing.
Jeff.
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Post by dubiousgolfer on Apr 3, 2020 10:21:04 GMT -5
Dr Mann
This is the principle of conservation of angular momentum:
Definition of conservation of angular momentum : a principle in physics: the total angular momentum of a system free of external torque remains constant irrespective of transformations and interactions within the system"
Are you theorising that the angular momentum of the 'golfer and club system' after P5.5 is conserved and that no other external forces are being applied to the system up to P7?
But what about any increase in the 'torques/forces' applied by the ground to the golfers feet? Wouldn't that be deemed as external 'forces/torques' being applied after P5.5? Or are you theorising that all the necessary ground forces/torques have already been applied before P5.5?
An analogy about a golf swing being done this way would be a golfer standing on a flat stable platform a few feet off the ground, swinging as per usual (using any ground forces between platform and feet), then just after P5.5 the platform is suddenly removed. The angular momentum of the 'golfer/club' system just before the platform is removed could then theoretically be conserved for the rest of the swing (if one ignored air friction and the effects of gravity).
Hope this makes sense because understanding angular momentum , torques , moments of force, angular velocity, angular acceleration, centripetal/centrifugal forces, D'Alembert principle , eccentric forces ,etc, are (in my opinion) the most non-intuitive trickier topics in physics.
DG
PS. Theoretically , one still needs to release PA#3 after P5.5 by the rotation of the left arm/forearm and this can still be done by a golfer without standing on the earth , but that small torque generated by the arm/forearm would still have to be matched by an equal and opposite torque elsewhere within the 'golfer/club' system.
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Post by imperfectgolfer on Apr 3, 2020 18:24:14 GMT -5
DG,
When I state that the COAM principle is operant during the release of PA#2, I am not referring to the golfer and his pivot-induced swing action, but I am simply referring to the double pendulum swing model involving the left arm and the clubshaft where energy going to the clubshaft due to the release of the PA#2 will cause the left arm to slow down if no further energy is inputted into the double pendulum swing model to prevent the left arm from slowing down (as will happen in a driven double pendulum swing model where further energy is inputted to prevent the left arm from slowing down).
Jeff.
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