Miura - parametric acceleration

[SteveT]

@ Michael Finney .... soooo, looking at the golfer face-on almost at impact, the lead arm and club are in line and being pulled up, or "going normal" by shoulder torque to impart centripetal force and parametric force too?

But, looking at a side view, the lead arm and club are NOT in-line... there is a large obtuse angle (aka "replacement" angle) between the arm and club shaft. So now we have a different take on the club-arm assembly. The arm and club are still being pulled up by the shoulder torque, but the club handle is now being pulled in by the arm rotating in adduction at the shoulder to reduce the radius of rotation of the hands.

So we now have two centers of rotation... for the face-on in-line arrangement, and for the side view obtuse angled arrangement. Could you differentiate between these different rotations in defining "parametric" acceleration and it's changing radius, "r" ??

It would also be nice to see the force diagrams by Mackenzie et al for these conditions. Thanks in advance.....

 

[Michael Finney]

human beings have a tough time seeing parametric acceleration from one view.....Let's say face on.......you have introduced a second view...down the line.....but the physics works in a 360 degree view........

Fact......the center of the gravity of the hands is in a certain spot at the top of the backswing......

Fact.....the center of gravity of the club ensemble is in a certain spot at the top of the backswing....(the location of the club ensemble's COG can be debated for days - do you add the weight of the hands? Does the speed of the club and the flexing of the shaft move this COG, etc...).......but we do know that this COG is slightly off the shaft and between the hands and the toe of the club...

These above two facts give us two COGs in space.......they have an important relationship to one another because they are about to dance around each other for the next .25 seconds until impact........the way these two points push and pull on each other (in 360 degrees - not just two angles like Steve T mentioned) during the downswing could be considered a form of parametric acceleration....parametric acceleration does not have to be "normal" to anything and it certainly doesn't have to exist just before impact.....these two points overshoot one another, they speed and slow one another, they are off plane and then become planar.......they form circles and ellipses ......they affect nesbit's alpha, beta, and gamma torques.....

They have a relationship that is mutually beneficial when it comes to generating speed........we can pump energy into the system BECAUSE of their offset nature.........if they were perfectly on plane with each other we could make one hell of a gyroscope, but we couldn't hit it very far...

True 3D hand path and it's relationship to the ever moving full club ensemble COG.......parametric acceleration in 360 degrees

 

[Michael Finney]

Jeffry, point the giant douche bag line at your name next post.......you've succeeded in turning Brian haters into Brian sympathizes with your douchebag nature.......you had at least 10 converts over there, but now they're turning on you and it looks like tba may be your only recruit...good luck with your trolling

 

[SteveT]

@ Michael Finney .... you write with confidence, authority and some knowledge, so I ask you in sincerity, do you have any engineering or physical sciences background? I respectfully ask this so I can gain a better perspective of what you have written in response to my rather simplified questions. I don't want to create confusion in my response, if any.

As you may know, I am an engineer, but not a teacher of the golfswing ... i.e. I may have more brains than talent or teaching skills. I have to be respectful of those who teach for a livelihood because they are on the front lines facing the ignorant, unreasonable and demanding "enemy"...

 

[Michael Finney]

None whatsoever

 

[Michael Finney]

The ever changing Nesbit "geometric center of curvature" is one way to define shortening or lengthening the radius......which can control (speed up or slow down) the outward movement of the club's COG away from the hands......in a sense, it's parametric acceleration (deceleration) because the shape and direction of the hand path ultimately control the trajectory of the club's COG?....

 

[lia41985]

Tiger circa 2000:
<iframe width="420" height="315" src="http://www.youtube.com/embed/tisHZUBAj2Q" frameborder="0" allowfullscreen></iframe>

 

[Michael Finney]

gimme is/was nmgolfer......nmgolfer discredits Brian and mandrin every chance he gets on another golf forum that is sorta small....douchebag was the nicest term i could come up with....i apologize to the regular posters if i offended them - i do hope i offended gimme

 

[ZAP]

No offense here. In fact that is probably my favorite insult.

 

[SteveT]

@ Michael Finney .... thanks for that clarification, and I reviewed Miura and Nesbit to better understand your responses to my question. Yes, it's the "resultant" CoG, or as I prefer the "Center of Mass", that defines the swing radii that show up in various (360º) views.

And, yes, the parametric acceleration can occur anywhere in the swing, however, to optimize the swing, the parametric acceleration must be forcefully applied in the two views approaching impact. What I was demonstrating is that different rotations occurs in different views or planes.

Jacobs has pointed out he observed a "replacement" of the lead arm and hand in the side view, and all I was pointing out that that replacement is also a "parametric" acceleration but in the side view and around the wrist joint center. The other parametric acceleration occurs around the shoulder torque center. Multiple parametric accelerations, if you wish.

However, I thought parametric "movement" involves the change in the position of swing centers, not only movement of the CoG towards and away from the swing center. If you review mandrin's "Parametric Acceleration" pages, I think you will agree.

 

[Billy McKinney]

I was just experimenting the above angles yesterday on the course. Does keeping the angle from aligning (dtl view) actually add or detract any power? I played 9 holes trying to keep that handle down and naturally drew everything (except when it hooked)..not the first time with this awareness, but first time with it mixed with un-coupling and parametric acc.

 

[Michael Finney]

@ Michael Finney .... thanks for that clarification, and I reviewed Miura and Nesbit to better understand your responses to my question. Yes, it's the "resultant" CoG, or as I prefer the "Center of Mass", that defines the swing radii that show up in various (360º) views.

And, yes, the parametric acceleration can occur anywhere in the swing, however, to optimize the swing, the parametric acceleration must be forcefully applied in the two views approaching impact. What I was demonstrating is that different rotations occurs in different views or planes.

Jacobs has pointed out he observed a "replacement" of the lead arm and hand in the side view, and all I was pointing out that that replacement is also a "parametric" acceleration but in the side view and around the wrist joint center. The other parametric acceleration occurs around the shoulder torque center. Multiple parametric accelerations, if you wish.

However, I thought parametric "movement" involves the change in the position of swing centers, not only movement of the CoG towards and away from the swing center. If you review mandrin's "Parametric Acceleration" pages, I think you will agree.

thanks for your post.......you said: parametric "movement" involves the change in the position of swing centers....

i guess this brings us back to the debate about what a "swing center" actually is - is it an anatomical center (like a shoulder, an elbow, a point between the hands, a point between the shoulders) or a geometric center determined by the "sharpness" of the hand path....i guess you could argue that both would be correct references when discussing the ever confusing, much bandied about term - SHORTENING THE RADIUS.....i think i could come up with 5 or 6 different explanations of how this term is defined on different golf forums......i don't know the answer, i just read smart people's findings

but i did enjoy your post and your thoughtfulness - thanks

 

[wulsy]

Could someone point out to me why this "lowering" of the hands (ie inside from DTL) accelerates the club, because when I do it I hit it shorter. If I understand swingfitman correctly, he may have had a similar experience. Thanks for any explanation in advance....

 

[spktho]

Could someone point out to me why this "lowering" of the hands (ie inside from DTL) accelerates the club, because when I do it I hit it shorter. If I understand swingfitman correctly, he may have had a similar experience. Thanks for any explanation in advance....

Post 72, Michael Finney and post 20, SteveT give the technical explanation. I think of it as adding a torque on the shaft that brings the club head from behind the hands to in front of the hands--the older termed "tumble"--and is a face squaring move too. The more the club is laid off in transition, the more you have to do it like Sergio and Hogan. I think if you don't "lay it off" as much then it can be overdone causing the face to close more. Getting the lead arm more vertical in the down swing aids the "tumble", which can also feel like getting the hands lower.

The "tumbling" torque (one form of parametric acceleration) alone adds some club head speed. But, I think getting the hands too low has an adverse affect on the left wrist action of ulnar deviation which leads to at least some of the decreased club head speed. This is also the reasoning behind gripping the club in ulnar deviation with the lead wrist.

So during the swing, the golfer can go from ulnar deviation at set up to little ulnar deviation at the top of the back swing to ulnar deviation at impact without "standing the handle up" at impact (which is an indication that little to no "tumble" has occurred). If the handle gets too low into impact, then ulnar deviation is less at impact.

No SteveT, I don't have the data to support my explanation, just anecdotal evidence as mentioned above and some biomechanics training.

 

[mandrin]

sorry for the threadjack - but is this how a swing in a children's playpark gains momentum - by pulling on the chains or ropes and shortening the radius?

always wondered about the physics of that - and forums discussing the golf swing are far more common than the other sort...

birly-shirly,

I am sure that looking at this information you will probably be surprised that you could do as a child instinctively such complicated actions without any knowledge of science.

Similarly with BM and his group striving for getting max scientific input into golf instruction it is very plausible finding some conventional golf wisdom to be scientifically correct and even quite optimum.

 

[SteveT]

Yes... but much of the explanation of the optimum "feeel" is based on intuitive physics using "post hoc ergo propter hoc" logic. Homer was a great "propter hoc-er".... and now tgm is just another golfswing method without a science to back it up.

Sometimes I can see Brian et al occasionally sinking back into intuitive physics ... from their own swing feelings and anecdotal teaching experiences... and coming up short on all the shientific scit from their team of experts, you included ....

Patience is a virtue, they say ... and the gold brick road to scientific nirvana can be a mighty rocky road ...

 

[wulsy]

spktho, thanks. Nice explanation. This increases the so-called beta-torque then?

 

[spktho]

Sometimes I can see Brian et al occasionally sinking back into intuitive physics ... from their own swing feelings and anecdotal teaching experiences... and coming up short on all the shientific scit from their team of experts, you included ....

Patience is a virtue, they say ... and the gold brick road to scientific nirvana can be a mighty rocky road ...

You're preaching to the choir here--by the way I am not one of their experts(obvious), if that's what you were implying with "you included"--which is why I qualified my explanation to you in hopes of not having a response, but my plan backfired.

 

[mandrin]

gimme is/was nmgolfer......nmgolfer discredits Brian and mandrin every chance he gets on another golf forum that is sorta small....douchebag was the nicest term i could come up with....i apologize to the regular posters if i offended them - i do hope i offended gimme

nmgolfer and jeffmann are assiduously reading and analyzing my posts, desperately trying to further their education. It is however rather pathetic just seeing them for ever just being negative, seemingly for its own sake. Michael, I do agree, douchebags seems to be quite appropriately qualifying such individuals.

 

[spktho]

spktho, thanks. Nice explanation. This increases the so-called beta-torque then?

Yep. As you know with everything else in the golf swing, it is not an isolated movement, though. Namely, along with the wrists, I think the shoulder complexes are very involved in helping to aid in the motion. Try protraction(pushing forward of just the shoulder) of the rear shoulder and retraction + elevation(pulling back and shrugging) of the lead shoulder about halfway into the downswing. I think this will also help in not losing any clubhead speed as it is a "going normal" move.