It's a Real Force, this Centrifugal Thing.

[savydan]

savydan,

Is it asking too much of your precious time to simply say thank you?

I take plenty of time and great care when responding to do so to the best of my knowledge.

Don't bother to react, it is too late by now. I am again rapidly losing interest in this forum.

Cripes. I just came over here after posting in another thread to say thanks and was thinking how best to word a follow-up question I wanted to ask.

Sorry I missed your deadline. If your interest is waning, please don't put it on me.

 

[Brian Manzella]

savydan,

To summarize, above constitutes a simple but fair approximation for centrifugal pull when only clubhead itself is considered. It concerns the maximum centrifugal force which exists for a small fleeting moment when arm and shaft are virtually in line just before impact. For the total centrifugal pull exerted on the lead shoulder joint one has to consider a small additional contribution by both shaft and lead arm.

Also it is a fair approach for someone letting the club rather freewheel though impact. However for a hacker, with a rather low clubhead speed, and really trying to muscle the clubhead through impact the ball, it is not. The instantaneous center of rotation for the club head is than moving towards the lead arm shoulder joint.

So what you are saying is that the centrifugal force is only felt by the golfer—or working on the club—for a brief moment in the swing?

 

[Brian Manzella]

Mandrin,

How does the fact that there is NO CENTER of the golf swing—only a instantaneous helical axis—effect all the Centrifugal and Centripetal forces in a golf swing?

Oh, thanks for all the work, past, present and to come.

 

[mandrin]

So what you are saying is that the centrifugal force is only felt by the golfer—or working on the club—for a brief moment in the swing?

Brian,

I mentioned previously that in general as soon as there is any deviation of any moving object from a straight line there are centripetal/centrifugal type forces coming into play relative to the instantaneous center of rotation. Hence they are present during ALL of the golf swing, back swing and forward swing.

To not dazzle people with mathematics I simply showed how to get a fair idea of the magnitude of the centripetal/centrifugal force when at its maximum, close to and just prior to impact. Hence only for one particular moment of time when reaching its maximum value and club shaft being approximately in line with lead arm.

Therefore, I am not suggesting that the “centrifugal force is only felt by the golfer—or working on the club—for a brief moment in the swing” but rather, quite different, clearly implying that the specific simplified calculations of my post are only valid for a rather short span of time just prior to impact.

 

[Jon Hardesty]

Great information to know! Thanks Mandrin for all the hard work! Keep up the good work!

 

[golfie]

Forces on the golfer

Mandrin,

Given that the golf club is not a rock on a string, does the club's center of gyration not come into play and possibly reduce the force on the golfer?

 

[mandrin]

Mandrin,

How does the fact that there is NO CENTER of the golf swing—only a instantaneous helical axis—effect all the Centrifugal and Centripetal forces in a golf swing?

Oh, thanks for all the work, past, present and to come.

Brian,

The notion of centripetal force/centrifugal force has been, by almost all, scientists and laymen alike, simply associated with a little object whirling with constant speed around a fixed center. It is perhaps a pity but the world is simply not made up of little objects all quietly circling about stationary centers.

The acrimonious discussions with nmgolfer in the past had precisely that back ground. He was, probably like many other scientists, simply not aware that reality is not made up of simple circling objects, but that instead golfers can only be truly analyzed using multibody dynamics. Hence a golfer is considered to be an ensemble of linked segments, having a rather sophisticated interplay.

Once you have linked segments better forget about a mass circling around a center. It then requires solving the governing differential equations to get an idea of the forces acting at the various segments and joints. These forces are indeed a complicated mix of interaction of various segments, moving relative to each other whilst connected by joints, which form non stationary instantaneous centers of rotation.

Hence with linked segments there are indeed centripetal/centrifugal like forces acting on each of them but they, very definitely, can't be formulated with the charming simple mathematical expressions used for describing a simple mass whirling around a stationary center with constant angular velocity.

Thanks for the thanks for all the work, past, present, and future.

 

[Damon Lucas]

Thanks Mandrin, terrific stuff!

This information is why I am skeptical of swing plane analysis.

On a basic level, swing planes look good, sound good, and are easy to sell to Joe Public, but when you have multiple segments moving at different rates and directions and with differing thrusts/torques while the golfer is trying to hit different shots with different clubs and different bodies, it is difficult to imagine any straight lines anywhere near the golfer!

Don't go any where, Mandrin. You are way too appreciated here by several people, and I would doubt you would get the same reception in too many other golf websites!

 

[Matt Bryda]

Mandrin'
Thank you very much for the information you provide. It is truly appreciated by me and others here I'm sure!

Matt

 

[mandrin]

Mandrin,

Given that the golf club is not a rock on a string, does the club's center of gyration not come into play and possibly reduce the force on the golfer?

golfie,

Indeed a golf club is not a point mass at the end of a string. But just remind your self that centrifugal force is than given by M R w^2, where w is angular velocity.

The essential factor to consider is the mass distribution. Hence the value of the mass but also its location relative to the center of rotation.

Hence....grip negligible, shaft very little but mass of head dominant, being concentrated and peripheral.

Therefore as a reasonable first order approximation one can consider a golf club as a point mass at the end of a very light rigid shaft.

 

[mandrin]

Thanks Mandrin, terrific stuff!

This information is why I am skeptical of swing plane analysis.

On a basic level, swing planes look good, sound good, and are easy to sell to Joe Public, but when you have multiple segments moving at different rates and directions and with differing thrusts/torques while the golfer is trying to hit different shots with different clubs and different bodies, it is difficult to imagine any straight lines anywhere near the golfer!

Don't go any where, Mandrin. You are way too appreciated here by several people, and I would doubt you would get the same reception in too many other golf websites!

Damon,

I agree, very well put. This swing plane stuff has been way over cooked. There are so many swing planes, sometimes even an infinite number if one listens to Frank Haney. It almost takes an engineering degree it understand it all. The plane concept is indeed very useful but don't try to squeeze everything into some type of swing plane approach. After all we are not flatlanders but 3D golfers.

Your remark about reception on other forums made me think about it, since it is full of interesting paradoxes.

My very first forum was a Moe Norman inspired Single-Axis Golf Forum. Real fun and being rather loyal stayed on for several years.

Came aboard on BM's forum and learned to shoot fast and precise from the hips, fully 360 degrees, not to get lynched. Too many TGM zealots around. With BM moving away from TGM gradually things calmed down. There were in the end only nmgolfer and his funny alter ego Bronco Billy around to keep me alert and sharp, shooting on target.

Tried to have some more 'fun' on a different TGM forum but even my very first post was intercepted and got a PM telling me that I was not welcome. Obviously they rather want a party between themselves and whilst jubilating and congratulating themselves continuously for their superior scientific approach are actually scared to death to have some real science around.

Last year I tried another TGM forum, but it lasted only for a bare 5 days before they pulled the plug, got banned, no message, no single reason being given. Very cheap approach, showing the typical attitude of unhealthy inbred attitude of sects.

Also last year started posting another forum, where, interestingly, there are several posters, including the forum's owner, all been banned from TGM forums. Rather warm reception as the owners response to one of my posts clearly shows -

“Thanks for the wonderful post Mandrin,

I know that took you a lot of time to put that together, and it's posts like that really make this such a wonderful site.“

It is clear from my experience that the TGM zealots are a very special crowd, probably frequently rather intelligent and very attracted to notions and systems promising absolutes. The religious background of HK must surely play a role in this very special intriguing approach to golf.

TGM as taught by some is definitely doomed to die, perhaps slowly but nevertheless steadily. By taking TGM to be the alpha and omega, both for golf-science and golf, one, consequentially, develops a resistance to any fresh science input as it might possibly threaten to shatter the sweet gratifying phantasy of belonging to a superior golfing race.

Perhaps a pity for some who continuously look for security but absolutely nothing is forever cast in stone. The wheel keeps turning but things are nevertheless with every turn never ever quite the same.

 

[Damon Lucas]

You are very right about the security that a system affords one. It is a much more difficult 'sell' to have multiple fixes and antidotes to people's swing issues.

Allow me, if you will, to ask this question? How has this forum stimulated your thoughts? Have your thoughts on the golf swing been persuaded in any direction by your interactions here?

Cheers,
Damon

 

[mandrin]

You are very right about the security that a system affords one. It is a much more difficult 'sell' to have multiple fixes and antidotes to people's swing issues.

Allow me, if you will, to ask this question? How has this forum stimulated your thoughts? Have your thoughts on the golf swing been persuaded in any direction by your interactions here?

Cheers,
Damon

Damon,

Ideas and concepts slowly emerge through interaction. Perhaps likely mostly by criticism of various kinds. That has a rather stimulating effect to prove one's idea's being correct. But in more recent years embracing D-plane and ball flight concepts are setting BM apart from most.

I found it very interesting to see BM's evolution over the years. I fully understand and sympathize that, once one spent many, many years to learn something really at a true guts level, how difficult it must be to really put it aside and start afresh with one's own ideas.

Moreover, as you pointed out, it is indeed very difficult to than embark upon and develop a teaching philosophy which is broad rather than narrow as selling is done much more easily with simple condensed concepts such as single plane golf, gravity golf, stack and tilt, etc.

I just can't remember which rather well known golf instructor was involved but have read it somewhere many moons ago that when giving lessons he did not allow other students to get close as he might give them contrary instructions.

Such is the problem faced by a real golf instructor who teaches directly from an immediate and intuitive knowledge about what each student might need. The pseudo single simple method teachers are likely mostly charming salesmen who whilst giving lessons might even think about all kind of things except his student.

Students of these latter type of teacher can happily exchange information as their teacher tells and teaches them all literally the same thing. The students might even take this as a prove that he knows his stuff. Whilst for a true teacher there is always the danger than when comparing various lessons given to different students one might find apparent contradictions.

Golf, like life in general, is a perpetual string of paradoxes, there is just no escape.

 

[birly-shirly]

Mandrin,

How does the fact that there is NO CENTER of the golf swing—only a instantaneous helical axis—effect all the Centrifugal and Centripetal forces in a golf swing?

So, whether or not you knew the answer, did everyone else understand the question?

Can someone put me out of my misery and explain what an instantaneous helical axis would look like or do in a golf swing?

Call me old-fashioned, but I'm still clinging to the idea that Cochrane & Stubbs put out of there being a conventional centre to the downswing, or at least a centre that shifts laterally as proposed by Jorgenson.

 

[Brian Manzella]

So, whether or not you knew the answer, did everyone else understand the question?

Can someone put me out of my misery and explain what an instantaneous helical axis would look like or do in a golf swing?

Call me old-fashioned, but I'm still clinging to the idea that Cochrane & Stubbs put out of there being a conventional centre to the downswing, or at least a centre that shifts laterally as proposed by Jorgenson.

"There is NO CENTER in the golf swing." Phil Cheetham

 

[birly-shirly]

"There is NO CENTER in the golf swing." Phil Cheetham

I'd like to better understand what both statements mean.

"instantaneous helical axis" means, I would guess, a center that continuously moves (in some sort of spiral path?)

"No center in the golf swing" seems to contradict the idea of a moving center.

Did both come from Phil?

 

[birly-shirly]

Taking now your 5 iron example....
M assumed about .3 kg
Assuming v about 145 km/h
R about 1.05 m
The centrifugal pull caused by clubhead is than approximately 464 N (104 lbs)

So, with some assumptions to simplify matters somewhat,

suppose this centrifugal pull occurs when the clubshaft is perfectly vertical, that the clubhead's CoG is aligned with the shaft, that impact with the ball hasn't quite occurred yet, and that the centrifugal pull is enough to instantaneously break the shaft

where does the club (the bit no longer attached to the grip!) go? does it fly vertically downwards, in the direction of the centrifugal force - or does it fly horizontally, in the direction of the clubhead's momentum?

 

[mandrin]

So, with some assumptions to simplify matters somewhat,

suppose this centrifugal pull occurs when the clubshaft is perfectly vertical, that the clubhead's CoG is aligned with the shaft, that impact with the ball hasn't quite occurred yet, and that the centrifugal pull is enough to instantaneously break the shaft

where does the club (the bit no longer attached to the grip!) go? does it fly vertically downwards, in the direction of the centrifugal force - or does it fly horizontally, in the direction of the clubhead's momentum?

Centrifugal Force Myth

“.....Again, here is another scientist stating that there is an outward force moving in the direction of the arrow shown in figure 3. This is incorrect. There is no centrifugal force pulling in the direction of the arrow. If there were such a force, the club could be released and the club would move in that direction. If you release a club at any time during the downstroke, it will go off at a tangent to the arc of the downstroke curve at the time of the release.....

You raise a similar point as by the infamous professor Jack Kuykendall, the self acclaimed World's Leading Scientific Golf Teacher, several years ago. He belittles many, yet is himself totally of base with his basic arguments.

However it is so simple to state the simple facts. Centripetal/centrifugal forces only and only exist when there is either a pushing or pulling force acting on an object towards a center, either stationary or not. When the club shaft breaks or club released, then, instantaneously, there isn't any force acting anymore on the clubhead and hence simply moves away tangentially. JK also comes to this conclusion but it is however completely illogical to use this fact to than deny subsequently the existence of centrifugal force.

He does not realize that centrifugal/centripetal force, by definition, only exist as long as there is a restraining force present and acting toward a center. When a club is released, immediately, there simply is no force acting anymore on the club, hence also no centrifugal force. Therefore, the motion of the club, after being released, can't be used as an argument either for or against the existence of the centrifugal force. That is simply very silly, but nevertheless a basic error made by too many.

 

[Brian Manzella]

I'd like to better understand what both statements mean.

"instantaneous helical axis" means, I would guess, a center that continuously moves (in some sort of spiral path?)

"No center in the golf swing" seems to contradict the idea of a moving center.

Did both come from Phil?

No fixed center.

Got it now?

 

[spktho]

Centrifugal Force Myth

“.....Again, here is another scientist stating that there is an outward force moving in the direction of the arrow shown in figure 3. This is incorrect. There is no centrifugal force pulling in the direction of the arrow. If there were such a force, the club could be released and the club would move in that direction. If you release a club at any time during the downstroke, it will go off at a tangent to the arc of the downstroke curve at the time of the release.....

You raise a similar point as by the infamous professor Jack Kuykendall, the self acclaimed World's Leading Scientific Golf Teacher, several years ago. He belittles many, yet is himself totally of base with his basic arguments.

However it is so simple to state the simple facts. Centripetal/centrifugal forces only and only exist when there is either a pushing or pulling force acting on an object towards a center, either stationary or not. When the club shaft breaks or club released, then, instantaneously, there isn't any force acting anymore on the clubhead and hence simply moves away tangentially. JK also comes to this conclusion but it is however completely illogical to use this fact to than deny subsequently the existence of centrifugal force.

He does not realize that centrifugal/centripetal force, by definition, only exist as long as there is a restraining force present and acting toward a center. When a club is released, immediately, there simply is no force acting anymore on the club, hence also no centrifugal force. Therefore, the motion of the club, after being released, can't be used as an argument either for or against the existence of the centrifugal force. That is simply very silly, but nevertheless a basic error made by too many.

Can't overlook the basics. As usual, great information.