Shaft Lag

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quote:Originally posted by MizunoJoe

quote:Originally posted by mandrin


forget the idea of a loaded shaft kicking.
mandrin,

A shaft kicks when the lagging clubhead starts overtaking the shaft. Do you think that all the photos of this phenomenon are illusions? Is all that launch monitor data a hoax? Do me a favor - go to the bombsquad forum and make that statement - now that would be fun to read! [:p]
MizunoJoe,

The very large centrifugal force, acting prior to and through impact, causes both stooping and forward bending - no unspringing, unloading or kicking of a shaft.

The word ‘kick’ is misleading as it invokes a spring like action. The shaft in the hands of a golfer is really overdamped and can’t oscillate during a golf swing

I am not usually impressed when many people think alike. Golf is indeed quite peculiar for having generated many myths, remarkable persistent over time. [8D]
 

bbftx

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Did anyone consider that more than ONE factor might be involved in clubhead lead?
If you guys get a chance to read the MacKenzie thesis I reference above, I think you'd find some common ground. His results from live golfer testing and his simulation model suggest that both some of the forces mandrin mentions, as well as shaft stiffness/recoil play a role in the amount of lead deflection. [Mandrin, you'll need to read beyond MacKenzie's use of the word "kick" --- he uses it a lot ---- but his work agrees with some of your analysis of the forces and reactions involved. ]

In particular, I'd point to some of his research hypotheses, which seem to be supported by his results. Note that next to last one below.

"-Golf shafts bend during the golf swing as a result of both tangential and radial forces relative to the grip end of the club during the downswing.
- Customizing the flexibility of a golf shaft to a specific swing will increase clubhead speed at impact, but not by a meaningful amount.
-Clubhead orientation at impact will depend upon both swing speed and shaft stiffness.
- Altering the position of the center of mass of the clubhead relative to the shaft will affect the dynamics of the club during the downswing."

The world is often not "black or white, one or the other." Perhaps more than one causal factor can be involved in golf swing phenomena?
 
“His results from live golfer testing and his simulation model suggest that both some of the forces mandrin mentions, as well as shaft stiffness/recoil play a role in the amount of lead deflection”

bbftx, in a thesis of several hundred pages one can put more information than in a few lines of a post. I referred to applied forces/torques, inertial forces and air drag forces. What are those other forces I seemingly did not mention?

However, to mention, as in your post, that shaft stiffness plays a role in shaft flexing is something I don’t mention in a short post since it is obvious. ;) Equally the force generated, due to flexing of shaft, is also similarly clear in this context.

I do feel that recoil has very little to do with the magnitude of the deflection at impact. If the shaft could act as a spring in the downswing it would make sense but the very small mechanical impedance of the soft biological tissues of the hands don’t allow this to occur.

"-Golf shafts bend during the golf swing as a result of both tangential and radial forces relative to the grip end of the club during the downswing.
- Customizing the flexibility of a golf shaft to a specific swing will increase clubhead speed at impact, but not by a meaningful amount.
-Clubhead orientation at impact will depend upon both swing speed and shaft stiffness.
- Altering the position of the center of mass of the clubhead relative to the shaft will affect the dynamics of the club during the downswing.


The above is rather common sense. But convincing research is probably required to change the tenacious myths and romantic hype concerning shafts and clubs.

As to the second point - only if one has a very flexible shaft such as in a whippy tempo master is it possible to start using somewhat more efficiently the potential energy, due to recoil/torque/force, to gain some additional clubhead speed at impact, for equal effort employed.
 

bcoak

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From Chapter 5 in Tom Wishon's new book, Common Sense Clubfitting: The Wishon Method:
"Let me start by first telling you what the shaft does NOT do in the swing. Many, in fact most, clubmakers and serious golfers think that the shaft “loads” up energy from its initial bending at the start of the downswing and then “unloads” in a buggy whip/spring action to slingshot the ball down the fairway. Most think that the shaft does this in a spring back then spring forward manner and that the right shaft really does increase the velocity of the clubhead when it hits the ball."
 
From Chapter 5 in Tom Wishon's new book, Common Sense Clubfitting: The Wishon Method:

"Let me start by first telling you what the shaft does NOT do in the swing.

Many, in fact most, clubmakers and serious golfers think that the shaft “loads” up energy from its initial bending at the start of the downswing and then “unloads” in a buggy whip/spring action to slingshot the ball down the fairway.

Most think that the shaft does this in a spring back then spring forward manner and that the right shaft really does increase the velocity of the clubhead when it hits the ball."



bcoak, thanks for posting above lines. Tom Wishon is known as the world’s leading club expert and it is pleasant to see his ideas to be identical to mine. [:I]

I invite my friend, MizunoJoe, to carefully read Tom Wishon. Perhaps it will then be less urgent for me to delve into completing the time consuming efforts to proof it all mathematically. :D

bbftx might find reading Wishon also quite instructive and perhaps ponder a bit about the meaning of the word “kick”. It is never too late to learn and accept ideas going against the comfortable accepted mainstream thinking. ;)
 

bbftx

New
mandrin
I've read Wishon and really enjoy his material. If you remember, it was me who sometime back told you about his shaft bending modeling software that is still in beta.
I pretty much agree with you on this topic, although you seem to want to fight about EVERYTHING. I do like you mandrin, although you seem to want to be confrontational about every topic.
 
Bbftx, I am not confrontational but rather quickly confronted by many. A subtle but rather important difference. [:p]

I have developed my own shaft bending modeling software, as Tom Wishon, in which the shaft is treated as a continuum.

I have also done the mathematical shaft modeling similarly to Sasho Mackenzie in his PhD research paper, ie. using 4 rigid segments, spring/damper equipped at the joints.

The mathematics involved in above modeling is very complex. In the latter case I started with 8 segments but finally only could get 4 segments to work. For more my software just refused to produce results.

I find pleasure in the challenge to do my own thing and this might explain perhaps why my opinions don’t often appear very wishy-washy. ;)
 
quote:Originally posted by mandrin


I have developed my own shaft bending modeling software, as Tom Wishon, in which the shaft is treated as a continuum.

I have also done the mathematical shaft modeling similarly to Sasho Mackenzie in his PhD research paper, ie. using 4 rigid segments, spring/damper equipped at the joints.

The mathematics involved in above modeling is very complex. In the latter case I started with 8 segments but finally only could get 4 segments to work. For more my software just refused to produce results.

I find pleasure in the challenge to do my own thing and this might explain perhaps why my opinions don’t often appear very wishy-washy. ;)

Where have you submitted this work for expert review and publication?
 
MizunoJoe,

I should have known that it would tickle your curiosity. :D I will partly satisfy it by letting you have a peek into the ‘kitchen’. ;) Not quite like HK but still of interest. [:p]

You can have a look here at one of the 4 hefty governing equations I have developed, considering the golf club as a continuous system. [8D]
 
quote:Originally posted by mandrin

MizunoJoe,

I should have known that it would tickle your curiosity. :D I will partly satisfy it by letting you have a peek into the ‘kitchen’. ;) Not quite like HK but still of interest. [:p]

You can have a look here at one of the 4 hefty governing equations I have developed, considering the golf club as a continuous system. [8D]

The instant I saw those equations, I realized that you are right and the shaft does not kick! [:I]
 
MizunoJoe, rather impressive. It was a painful struggle eventually resulting into those 4 equations, all required to deal with a flexible shaft in a golf swing, but only a quick look at only one and you immediately concluded correctly. :)
 
quote:Originally posted by MizunoJoe

The instant I saw those equations, I realized that you are right and the shaft does not kick! [:I]


MizunoJoe:

While I would be the first to admit that a cursory glance at the equation would cause one to draw such a conclusion, closer scrutiny reveals a fatal flaw, which, if corrected, undeniably proves that a shaft DOES kick. (In line 12, what should have been a 'plus' sign is shown as a 'minus'.)

I just spent the last three days reviewing the equation - sorry it took so long, but mathematics is not my strong suit - and I am convinced this is the case. Ironically, part of the equation also seems to support a GYROSCOPIC MODEL of the golf stroke, but this needs further investigation.;)

hiro
 
quote:Originally posted by hiroshiro



While I would be the first to admit that a cursory glance at the equation would cause one to draw such a conclusion, closer scrutiny reveals a fatal flaw, which, if corrected, undeniably proves that a shaft DOES kick. (In line 12, what should have been a 'plus' sign is shown as a 'minus'.)

I missed that hiro - good eye! Now I'm comfortably back in the kick camp. [:p]
 
C'mon Mandrin.....those aren't math equations.......u just seated a monkey at your computer for a couple days and let the bugger go nuts.

;) jk mandrin.
 
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