|
Post by dubiousgolfer on Mar 9, 2021 21:13:01 GMT -5
Dr Mann Yes that makes sense . So do you think the below image is more indicative of the theoretical forces being applied via the hands from P4-P4.5? 1. I've repositioned the left hand red arrow forces so that they are more towards the butt end of the club and slightly down. 2. I've added a PP1 'extensor' force arrow which MUST pass through the 'Mid-Hand Point' so that it doesn't affect the 'Hand Couple'. This PP1 force is pointing in such a direction that it will cause a negative MOF that will tend to assist the retention of the PA2 angle without interfering with the natural PA#2 release via the left hand. Having the PP1 force below the mid-hand point (towards the clubhead end direction) will tend to assist an early release (ie. increase the positive hand couple) , while above the MH point (in the butt end direction) could also delay the natural release (too much PP1 and negative MOF). 3. I've added some yellow arrows to try and reflect some of the forces that might be applied by the left and right thumb areas (not quite sure about this). As you can see there is still a positive hand couple about the 'Mid-Hand Point' but a negative 'Net MH Force MOF' which I hope complies with the inverse dynamic graphs. DG
|
|
|
Post by imperfectgolfer on Mar 9, 2021 22:50:33 GMT -5
Very nice image!
Yes - I can agree with how you have represented the forces.
The "extensor action" force is probably very small because many pro golfers (eg. Dustin Johnson and Adam Scott) seem to be able to naturally keep their lead arm very straight without any apparent need for an "extensor action" force.
Jeff.
p.s. What app do you use to draw arrows etc.?
|
|
|
Post by dubiousgolfer on Mar 9, 2021 23:13:03 GMT -5
Dr Mann
I just use some free application I downloaded from 'Microsoft Store' called Trio (its very basic and they always prompt one to buy their premium package- very annoying!) . I think 'Google Docs', which is also free (if you have a Google account) has the same basic functions .
I just copy and paste images from the internet into a Trio 'drawing docs' template , then just use whatever features it offers (to add arrows , lines, shapes ,text boxes , etc ).
Unfortunately , I cannot copy and paste directly into these posts and have to first copy/paste from Trio into golf forum 'private email message' facility (ie. copy and paste the images into email messages which I send to myself within the forum website). Then I have to copy the 'image link' from the email message and paste to these posts using the 'insert image ' icon.
So it takes quite a bit of time to create and post images.
DG
|
|
|
Post by imperfectgolfer on Mar 11, 2021 11:40:03 GMT -5
DG,
Thanks for recommending Trio.
I have sent you a personal message re: Choi paper.
Jeff.
|
|
|
Post by dubiousgolfer on Mar 31, 2021 13:20:40 GMT -5
This video below is an inverse dynamics graph of Cory Bacon's 7 iron swing (using grip coordinate system). SMK also compares the graphs with those created 'within' a swing plane coordinate system to show how problematic it becomes to assess what is being done by the golfer when using a fixed grip coordinate system. Further below , I will post a twitter video links of Cory Bacon's golf swing. It seems to show that there is very little cross shaft forces in the downswing while dominant forces along the shaft axis. Maybe it isn't worth too much effort overanalysing the kinetics aspect of the hand forces across the shaft. In fact it looks like the forces are mostly in the negative direction of the grip coordinate axis (ie. across the shaft) from about P5.5 onwards. Further, looking at the hand couple graphs by 'SMK/Kwon/Nesbit/Choi/Koike' , there seems to be quite a variation in the timing and magnitude. There is definitely some positive hand couple just before the MOF takes over but only for a miniscule period of time for SMK & Kwon graphs. DG
|
|