Miura - parametric acceleration

[SteveT]

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.

I think you should stop at the hands with your "biomechanics" training, because you fail to explain how "tumbling" the clubhead around it's longitudinal axis (located above the shaft, in the air) "alone adds some clubhead speed". Assuming you hit the ball on the clubface sweetspot, which incidentally is found on that same longitudinal axis, how does the clubhead impart forces to increase clubhead speed... or even include "parametric acceleration"??

I have written on this subject before, and explained why torquing the shaft-hand assembly does not increase clubhead speed.... it may feel forceful snapping the arm to supinate the hand, but what forces are imparted to the head that will hit the ball harder off the sweet spot?

 

[spktho]

I think you should stop at the hands with your "biomechanics" training, because you fail to explain how "tumbling" the clubhead around it's longitudinal axis (located above the shaft, in the air) "alone adds some clubhead speed". Assuming you hit the ball on the clubface sweetspot, which incidentally is found on that same longitudinal axis, how does the clubhead impart forces to increase clubhead speed... or even include "parametric acceleration"??

I have written on this subject before, and explained why torquing the shaft-hand assembly does not increase clubhead speed.... it may feel forceful snapping the arm to supinate the hand, but what forces are imparted to the head that will hit the ball harder off the sweet spot?

Point taken. I know its going back to the older discussion, but does the push of the right hand and the pull of the left hand on the handle that causes the club head to go from behind the body to in front of the body aid in accelerating the club head in any way?

Since you are poking holes in my understanding of physics terminology with my explanation, please help me and wulsy out by giving us a more correct explanation in laymen terms while relating it to the body motion during the golf swing.

 

[gmbtempe]

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.

I really could care less about the who, negative, etc, but does his critique have any merit?

 

[greenfree]

Interesting, usually Mandrin you answer these questions with diagrams and a good explanation etc., but now you're resorting to insults because someone hurt M.F's feelings, unlike you. Why not respond to Greg's question? I myself find your swing analysis not to be exactly convincing bordering on incorrect, maybe even the opposite of what really happens, what say you. I think you're slipping.

 

[Brian Manzella]

Just for the record.....

Mandrin's first post on Parametric Acceleration on this forum was in 2007.....

Art Maffai has been telling us (and we have been telling our students) to use the shoulder complexes for a couple of years....

Yawn....

 

[drewyallop]

@ 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.....

I feel this when I occasionally hit a good shot.

 

[spktho]

Just for the record.....

Mandrin's first post on Parametric Acceleration on this forum was in 2007.....

Art Maffai has been telling us (and we have been telling our students) to use the shoulder complexes fro a couple of years....

Yawn....

I'm not trying to tell you anything new, Brian, just trying explain my version of putting some of the many pieces together that I have learned here.

 

[drewyallop]

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 ...

Terrible mixed metaphor Engineer Steve. Not clever, just annoying. Plain English please.

 

[SteveT]

Terrible mixed metaphor Engineer Steve. Not clever, just annoying. Plain English please.

Where ignorance is bliss, 'tis folly to be wise.

You're so wise ....!

I feel this when I occasionally hit a good shot.

What does she say ....?

 

[lia41985]

Tiger Woods:
https://picasaweb.google.com/Lukman...gCKLBiorL_pbiUQ#slideshow/5686979260937370386
https://picasaweb.google.com/Lukman...gCNTuud2SyML2CA#slideshow/5686978490808111762
https://picasaweb.google.com/Lukman...CIOCu_mfivrpnAE#slideshow/5686975573420318130

Sergio Garcia:
https://picasaweb.google.com/Lukman...gCKqt1cX-lsKySA#slideshow/5686975976719269714

Jim Furyk:
https://picasaweb.google.com/Lukman...CNqDmtjn0rDJ0QE#slideshow/5686980238803774130

Johan Edfors (watch the travel of the buttcap from pictures 1 through 4):
https://picasaweb.google.com/Lukman...gCKST6Nq-z7LCMg#slideshow/5686981961860640674

Ben Hogan:
https://picasaweb.google.com/Lukman...CMDuj8O5zcbU8wE#slideshow/5686975177921741666

 

[SteveT]

Point taken. I know its going back to the older discussion, but does the push of the right hand and the pull of the left hand on the handle that causes the club head to go from behind the body to in front of the body aid in accelerating the club head in any way?

Since you are poking holes in my understanding of physics terminology with my explanation, please help me and wulsy out by giving us a more correct explanation in laymen terms while relating it to the body motion during the golf swing.

Okay, let's do an experiment using a long iron and a slim stake driven into the ground inclined towards yourself at the approximate club lie angle. Assume a static impact position and place the sweet spot of the clubhead against the inclined stake as if it were the ball and then gently supinate your hand by rotating your lead arm only. Use your rear hand to gently support the rotating club. You get the idea.

The clubface should only rotate against and around the inclined stake without knocking it down. That's the "force" the ball will experience when you forcefully "flip" the clubhead through impact... nil. If you hit towards the toe or heel, you will slap the ball in the direction of the movement... not good!

It may "feel" good forcefully snapping your lead forearm and hand axially, but that's not "power" hitting the ball... you're just "screwing" around. Now, if you are coming in square and straight into the ball, you have eliminated something that you can't consistently time into impact. Of course, a strong "centripetal" force application by "going normal" will stretch out your lead arm in line with the club, and that will help square up the clubface for impact. The axial rotation of the clubhead prior to impact should be completed well behind the ball.... because you should be maxing out the centripetal force to "go normal" into impact.

I'll stop here because too many words may confuse you and upset my "explanation in laymen terms"....

 

[spktho]

Okay, let's do an experiment using a long iron and a slim stake driven into the ground inclined towards yourself at the approximate club lie angle. Assume a static impact position and place the sweet spot of the clubhead against the inclined stake as if it were the ball and then gently supinate your hand by rotating your lead arm only. Use your rear hand to gently support the rotating club. You get the idea.

The clubface should only rotate against and around the inclined stake without knocking it down. That's the "force" the ball will experience when you forcefully "flip" the clubhead through impact... nil. If you hit towards the toe or heel, you will slap the ball in the direction of the movement... not good!

It may "feel" good forcefully snapping your lead forearm and hand axially, but that's not "power" hitting the ball... you're just "screwing" around. Now, if you are coming in square and straight into the ball, you have eliminated something that you can't consistently time into impact. Of course, a strong "centripetal" force application by "going normal" will stretch out your lead arm in line with the club, and that will help square up the clubface for impact. The axial rotation of the clubhead prior to impact should be completed well behind the ball.... because you should be maxing out the centripetal force to "go normal" into impact.

I'll stop here because too many words may confuse you and upset my "explanation in laymen terms"....

I don't think you are giving an explanation for the same movement. It seems that you are explaining a "twist" (gamma) by supinating the lead wrist near impact, but the motion I was trying to explain is defined in Nesbit's article as the "pitch"(beta) motion of the club.

In reviewing the motions section of Nesbit's article again he does state the beta motion is the "smallest of the angular motions...but still significant". It should also be noted that the scratch golfer had the least amount of pitch motion, suggesting that it is "not related to club head velocity".

Nesbit goes on to say about the gamma motion(twist about the longitudinal axis) that "it does contribute to the overall club head velocity"(page 12). So who should we believe?

And I'll stop there so I don't further confuse you about what you are confused about what I am trying to explain...

 

[SteveT]

I don't think you are giving an explanation for the same movement. It seems that you are explaining a "twist" (gamma) by supinating the lead wrist near impact, but the motion I was trying to explain is defined in Nesbit's article as the "pitch"(beta) motion of the club.

In reviewing the motions section of Nesbit's article again he does state the beta motion is the "smallest of the angular motions...but still significant". It should also be noted that the scratch golfer had the least amount of pitch motion, suggesting that it is "not related to club head velocity".

Nesbit goes on to say about the gamma motion(twist about the longitudinal axis) that "it does contribute to the overall club head velocity"(page 12). So who should we believe?

And I'll stop there so I don't further confuse you about what you are confused about what I am trying to explain...

I'm wrong.... you're right.... I'm too lazy to restudy Nesbit.... and Idon'tgiveash!tanymore ....

 

[brianid]

What are you guys talking about? Can someone summarize what each side is saying, please?

 

[brianid]

Okay, let's do an experiment using a long iron and a slim stake driven into the ground inclined towards yourself at the approximate club lie angle. Assume a static impact position and place the sweet spot of the clubhead against the inclined stake as if it were the ball and then gently supinate your hand by rotating your lead arm only. Use your rear hand to gently support the rotating club. You get the idea.

The clubface should only rotate against and around the inclined stake without knocking it down. That's the "force" the ball will experience when you forcefully "flip" the clubhead through impact... nil. If you hit towards the toe or heel, you will slap the ball in the direction of the movement... not good!

It may "feel" good forcefully snapping your lead forearm and hand axially, but that's not "power" hitting the ball... you're just "screwing" around. Now, if you are coming in square and straight into the ball, you have eliminated something that you can't consistently time into impact. Of course, a strong "centripetal" force application by "going normal" will stretch out your lead arm in line with the club, and that will help square up the clubface for impact. The axial rotation of the clubhead prior to impact should be completed well behind the ball.... because you should be maxing out the centripetal force to "go normal" into impact.

I'll stop here because too many words may confuse you and upset my "explanation in laymen terms"....[/QUOTE
SteveT,

Is what you're saying still true if the longitudinal axis of the left arm is NOT in line or parallel with the longitudinal axis of the shaft/hosel?