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Post by imperfectgolfer on Nov 27, 2018 10:00:16 GMT -5
Dr Mann - I've sent your questions to Sasho/Dave (but no reply yet). With regards Sasho's one arm swing , I noticed that he didn't show much lateral flexion in the downswing . Isn't this because there is no need for him to create room for his rear elbow to pitch near his rear hip in a TGM swingers action? Wouldn't this be a pointer to the use of the rear arm when added to the swing? From what I gather , clubhead speed is dependent on hand speed and path so can we tenuously assume that the use of the rear arm is being used to affect those 2 factors? That the biomechanical combination of the 'the weight pressured rear hip', 'activation of illiopsoas combined with lateral flexion' , 'rear arm adduction + shoulder moving down plane (PA5)' is creating a downswing path from 'P4- Release Point' that is less curved or faster (or both) by the addition of the right arm? I find Sasho's video (In Plane Couples and Moments Of Force) interesting from a physics perspective but also confusing from a biomechanics standpoint. Trying to imagine 'couples/net forces' combinations happening either independently or secondary to other movements can be confusing (ie. difficult to imagine how they are incorporated into a real life golf swing). I actually find this previous video by Sasho much simpler/easier to perceive forces/torques in the golf swing than his follow-up video. DG DG, You asked-: " With regards Sasho's one arm swing , I noticed that he didn't show much lateral flexion in the downswing . Isn't this because there is no need for him to create room for his rear elbow to pitch near his rear hip in a TGM swingers action? Wouldn't this be a pointer to the use of the rear arm when added to the swing?
From what I gather , clubhead speed is dependent on hand speed and path so can we tenuously assume that the use of the rear arm is being used to affect those 2 factors?
That the biomechanical combination of the 'the weight pressured rear hip', 'activation of illiopsoas combined with lateral flexion' , 'rear arm adduction + shoulder moving down plane (PA5)' is creating a downswing path from 'P4- Release Point' that is less curved or faster (or both) by the addition of the right arm?The answer is "yes" to all three questions. I have discussed all these issues in great detail in my new review paper on Tyler Ferrell's "Stock Tour Swing" which should be completed within 7 -10 days. Thanks for sending my questions to Sasho M and David T. Jeff.
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Post by imperfectgolfer on Nov 27, 2018 10:39:28 GMT -5
DG, I still have a problem understanding Sasho's need for a couple explanation. Here is a capture image from his video. Note that when the hands go down in a circular manner that moves the hands below the horizontal yellow line, that the club moves up but the angle between the club and the left arm does not change. I can understand the concept of the moment force causing the club wanting to line up with the club handle when the handle moves downwards towards the ground and that represents the D'Alembert principle in play - as described by nm golfer at nmgolfscience.tripod.com/release.htmHowever, the club does not release, and the angle between the clubshaft and the left arm remains the same, between image 1 and image 3 above.
What prevents the club releasing in a counterclockwise direction between image 1 and image 3? I could imagine that it is the presence of the RFFW and bent right wrist, that holds back the clubshaft by providing a counteracting pull in a clockwise direction. Why is that explanation not satisfactory, and why does one have to invent a couple theory? Consider an analogy - by thinking of an Iron Byron golf club testing machine. The club handle is attached to the central arm at a passive hinge joint. Surely there is no couple at play at that hinge joint. Also, when the central arm moves during the downswing it causes the hinge joint to trace a circular path and that causes the club to passively release via the physics underlying the D'Alembert principle. The designers of the Iron Byron machine prevent the club from prematurely releasing by using a "stop" that is controllably released during the mid-dowswing. I think that the RFFW/ bent right wrist acts like a "stop" that prevents a premature release of the club happening before P5.5. What is wrong with that explanation?
Look at Jon Rahm's hand arc path.
Image 1 is at P4, image 2 is at P5, image 3 is at P5.25 and image 4 is at P5.5.
Note that his hands travel straight down the hand arc path between P4 and P5.25. The hand arc path is very straight during that time period, so according to the D'Alembert principle, very little club releasing force is generated. So, it's easy to "hold" back the club with the bent right elbow/bent right wrist alignment where the right hand travels down the hand arc path at the same speed as the left hand.
Starting at about P5.25 - P5.5 the hand arc path moves more towards the target and that will generate a greater degree of club-releasing force. During this club releasing time period, the right arm starts to straighten thereby ensuring that the RFFW/bent right wrist do not impede the release of PA#2.
What is wrong with my explanation, which doesn't invoke the couple theory?
Jeff.
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Post by dubiousgolfer on Nov 27, 2018 17:50:44 GMT -5
Dr Mann- I prefer your explanation.
Here is Dave Tutelman's reply (Sasho has not commented yet).
DG -------------------------
So... What does the rear arm do for the swing, especially for distance?
In the first place, I don't think it has anything to do with the hand couple. I have a few hypotheses of what it does, but it is entirely possible that none of them is valid. Moreover, I think it would take a pretty clever biomechanist to formulate and conduct an experiment to test either hypothesis. (That is, to perform an experiment that would eliminate other hypotheses.) If my hypotheses were to be tested analytically rather than experimentally, it would have to be forward dynamics. Inverse dynamics cannot resolve the contributions of the right vs the left hand; that is called the "closed loop" problem.
With that disclaimer in place...
(1) Let's look at 'Dubious Golfer's' speculation that it could be the thing that makes Lee Comeaux' swing give more distance. (http://tutelman.com/golf/swing/leecommotion1.php#Why_It_Works) In that admittedly speculative work, I guess that it has to do with a shortened lever arm early in the downswing allowing the body to rotate faster. It is not the hand couple that does it. It is body rotation that makes the hands move faster and therefore exert more pulling force on the handle.
I have to admit I don't have a lot of confidence in this hypothesis. But the work I did learning the C-motion swing and trying to analyze it did help me come up with two other, more likely IMHO, hypotheses.
(2) Another possible reason is that there is another hand and arm able to move the left arm along its "track". In Sasho's 3D forward dynamics model, that would correspond to amplifying the left shoulder effort, creating separation between the left arm and the torso. In fact, when I tried my own C-motion swing on a launch monitor, I got about a 10% increase in clubhead speed when I did not try to hit with the right hand, but rather focused on trying to push the left hand off the butt of the club with the right. In other words, use the right hand to amplify the pull of the left, and explicitly do not try to exert hand couple with the right hand. (http://tutelman.com/golf/swing/leecommotion3.php)
(3) I'm no expert here in a formal or professional sense, so feel free to ignore this hypothesis.
It may well be more a confidence issue than something that is easily physically analyzed. Or, rather than just confidence, there is a real stabilizing influence by having both hands involved. With that influence in place, the golfer is free to make a stronger golf swing with ALL parts of the body.
Let me start with a discussion of the opposite one-hand swing, just the right hand. When I started learning the C-motion swing, I found I could not do the right-hand-only exercise that Lee recommends as the first step. (http://tutelman.com/golf/swing/leecommotion1.php#Experience_With_The_Swing) I would get the clubface on the ball only about a quarter of the time. That's not good. Adding the left hand stabilized the swing so the right hand could do its work.
Is there a similar effect one can attribute to a left-arm-only swing? Very likely! When I do a left-only swing, it feels just fine in the last part of the downswing, where the left arm is pulling and inertial effects are the main thing going on with the club. But it feels rather unstable in the area of transition, where speeds are low and the one-hand couple has to control the entire club against gravity. That is both alpha (in-plane) and beta (perpendicular to the plane) motion that needs to be controlled with the hand couple. Having a right hand to help exert the couple when the club is moving slowly can stabilize the swing and allow it to get in the proper position for the inertial release late in the downswing.
As I said up front, the added stability early in the downswing frees the golfer up to make the strongest swing possible. This may just be confidence, or the ability to focus effort on the turn rather than keeping the club on-plane, or it may be something else.
Hope this addresses the question. I know it doesn't ANSWER the question, because it is still at the unsupported hypothesis stage.
Cheers! DaveT
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Post by dubiousgolfer on Nov 27, 2018 19:09:30 GMT -5
Dr Mann
If you look at those Koike graphs again (before the 2 lines cross) , the force line for the right hand in graph (a) is a positive push force , but this is causing a 'negative' torque in graph (b).
When I learned about levers and moments of force at school , there was never a mention about 'coupling points' . As far as I'm concerned the fulcrum is the left wrist joint and the PP1 pressure force exerted by the base of the right thumb on that grip is a positive push force whose value is greater than the 'total negative' force exerted by the last 3 fingers (assuming there were enough sensors). But because the PP1 force is a lot closer to the fulcrum (ie. left wrist joint) , its 'positive moment of force ' is still less than the 'negative moment of force' by the last 3 fingers.
Could this explain why the graphs for the right hand show a positive force but negative torque at similar time points in the downswing (until they cross)?
If the above is true wouldn't this support your explanation above , that RFFW and bent right wrist holds back the clubshaft by providing a counteracting pull in a clockwise direction?
DG
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Post by imperfectgolfer on Nov 28, 2018 1:01:24 GMT -5
Dr Mann- I prefer your explanation. Here is Dave Tutelman's reply (Sasho has not commented yet). DG ------------------------- So... What does the rear arm do for the swing, especially for distance? In the first place, I don't think it has anything to do with the hand couple. I have a few hypotheses of what it does, but it is entirely possible that none of them is valid. Moreover, I think it would take a pretty clever biomechanist to formulate and conduct an experiment to test either hypothesis. (That is, to perform an experiment that would eliminate other hypotheses.) If my hypotheses were to be tested analytically rather than experimentally, it would have to be forward dynamics. Inverse dynamics cannot resolve the contributions of the right vs the left hand; that is called the "closed loop" problem. With that disclaimer in place... (1) Let's look at 'Dubious Golfer's' speculation that it could be the thing that makes Lee Comeaux' swing give more distance. (http://tutelman.com/golf/swing/leecommotion1.php#Why_It_Works) In that admittedly speculative work, I guess that it has to do with a shortened lever arm early in the downswing allowing the body to rotate faster. It is not the hand couple that does it. It is body rotation that makes the hands move faster and therefore exert more pulling force on the handle. I have to admit I don't have a lot of confidence in this hypothesis. But the work I did learning the C-motion swing and trying to analyze it did help me come up with two other, more likely IMHO, hypotheses. (2) Another possible reason is that there is another hand and arm able to move the left arm along its "track". In Sasho's 3D forward dynamics model, that would correspond to amplifying the left shoulder effort, creating separation between the left arm and the torso. In fact, when I tried my own C-motion swing on a launch monitor, I got about a 10% increase in clubhead speed when I did not try to hit with the right hand, but rather focused on trying to push the left hand off the butt of the club with the right. In other words, use the right hand to amplify the pull of the left, and explicitly do not try to exert hand couple with the right hand. (http://tutelman.com/golf/swing/leecommotion3.php) (3) I'm no expert here in a formal or professional sense, so feel free to ignore this hypothesis. It may well be more a confidence issue than something that is easily physically analyzed. Or, rather than just confidence, there is a real stabilizing influence by having both hands involved. With that influence in place, the golfer is free to make a stronger golf swing with ALL parts of the body. Let me start with a discussion of the opposite one-hand swing, just the right hand. When I started learning the C-motion swing, I found I could not do the right-hand-only exercise that Lee recommends as the first step. (http://tutelman.com/golf/swing/leecommotion1.php#Experience_With_The_Swing) I would get the clubface on the ball only about a quarter of the time. That's not good. Adding the left hand stabilized the swing so the right hand could do its work. Is there a similar effect one can attribute to a left-arm-only swing? Very likely! When I do a left-only swing, it feels just fine in the last part of the downswing, where the left arm is pulling and inertial effects are the main thing going on with the club. But it feels rather unstable in the area of transition, where speeds are low and the one-hand couple has to control the entire club against gravity. That is both alpha (in-plane) and beta (perpendicular to the plane) motion that needs to be controlled with the hand couple. Having a right hand to help exert the couple when the club is moving slowly can stabilize the swing and allow it to get in the proper position for the inertial release late in the downswing. As I said up front, the added stability early in the downswing frees the golfer up to make the strongest swing possible. This may just be confidence, or the ability to focus effort on the turn rather than keeping the club on-plane, or it may be something else. Hope this addresses the question. I know it doesn't ANSWER the question, because it is still at the unsupported hypothesis stage. Cheers! DaveT DT wrote the following with respect to the value of adding a rear arm to a TGM swinging action (lead arm swinging action)-: " Is there a similar effect one can attribute to a left-arm-only swing? Very likely! When I do a left-only swing, it feels just fine in the last part of the downswing, where the left arm is pulling and inertial effects are the main thing going on with the club. But it feels rather unstable in the area of transition, where speeds are low and the one-hand couple has to control the entire club against gravity. That is both alpha (in-plane) and beta (perpendicular to the plane) motion that needs to be controlled with the hand couple. Having a right hand to help exert the couple when the club is moving slowly can stabilize the swing and allow it to get in the proper position for the inertial release late in the downswing." I think that DT's statement that I have bold-highlighted is so vague and imprecise that it cannot shed any light on how the right arm/hand can be used fruitfully in a TGM swinging action. He makes no attempt to describe the role of the right arm/hand in any way that can be considered to even be somewhat qualitative. Didn't DT criticise Homer Kelley's TGM work and my work by stating the following-: " Let me start by responding to something that was in a more detailed email you sent me the other day asking essentially the same question. When I wrote my introductory article on modeling the swing in 2012 (http://tutelman.com/golf/swing/models.php), I explicitly excluded Homer Kelley's TGM. Here's a quote from the very first page of that article. "It is certainly a detailed discussion of the bones, muscles, joints, and club during the golf swing. But it falls short of a model in that it is all qualitative. There is nothing there that tells you how to analyze it mathematically, nor has that analysis ever been attempted (to my knowledge, anyway)."
That is my view of Dr Mann's work as well: very interesting video-supported discussions of fine aspects of the golf swing, but completely qualitative. There is no attempt to put measurement on the forces and torques, so it is not a kinetic model. Sometimes he is working a problem that biomechanics has modeled, but often not so."
I agree that HK's TGM work and my work is qualitative, and not quantitative in the sense that it can be mathematically analysed in terms of forces/torques, but at least I have described in considerable detail how the right arm/hand can be biomechanically used to assist a TGM swinger in more efficiently performing a TGM swinging action. By contrast, DT offers no qualitative details at all on how the right arm/hand can be used to make a TGM swinging action more efficient.
It's bizarre because DT is so amazingly precise and detailed when it comes to his mathematics-based articles on the behaviour of the golf club. Why can he not even describe in a reasonably qualitative manner how the right arm/hand can make a TGM swinging action more efficient? Jeff.
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Post by imperfectgolfer on Nov 28, 2018 1:08:38 GMT -5
Dr Mann If you look at those Koike graphs again (before the 2 lines cross) , the force line for the right hand in graph (a) is a positive push force , but this is causing a 'negative' torque in graph (b). When I learned about levers and moments of force at school , there was never a mention about 'coupling points' . As far as I'm concerned the fulcrum is the left wrist joint and the PP1 pressure force exerted by the base of the right thumb on that grip is a positive push force whose value is greater than the 'total negative' force exerted by the last 3 fingers (assuming there were enough sensors). But because the PP1 force is a lot closer to the fulcrum (ie. left wrist joint) , its 'positive moment of force ' is still less than the 'negative moment of force' by the last 3 fingers. Could this explain why the graphs for the right hand show a positive force but negative torque at similar time points in the downswing (until they cross)? If the above is true wouldn't this support your explanation above , that RFFW and bent right wrist holds back the clubshaft by providing a counteracting pull in a clockwise direction? DG I cannot even understand the Koike graphs, so I therefore cannot hope to understand your questions. Physics is my weak point and I try to avoid discussing concepts that are based on physics/mathematics. You will need to simplify your questions if you want me to venture an opinion that could be deemed to be reasonably rational. Jeff.
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Post by dubiousgolfer on Nov 28, 2018 12:08:10 GMT -5
Dr Mann Just found this pdf from Koike which imho shows clearer graphs (with golf swing avatars linked to parts of the graph). ojs.ub.uni-konstanz.de/cpa/article/download/6828/6125Graph b Quite interesting because it seems to show (if I've interpreted this correctly) that this golfer was not pulling with his right hand/arm through the shaft Y axis of the club. In fact it seems like the right hand was actually resisting the pull of the left hand in some constant fashion virtually throughout the downswing but then slightly less from P6 -P7. The downswing pull down the Y axis of the shaft is virtually all left hand with a greater rate of increase from release into impact (but quite a smooth curve). Graph c Again (if I've interpreted this correctly) , the right hand involvement in PA3 release around Z axis seems to be greater than left hand from around P6 and maximising torque around P6.3 and decreasing to zero around P7. Graph a It seems that the left hand is retarding PA2 release while right hand promoting PA2 release (in the x-axis at any instantaneous moment). But that the right hand force in the x-axis is always slightly larger which means PA2 release is actually occurring (albeit in small amounts up to release) from P4 . I'm not an expert in deciphering graphs so maybe you can provide a better opinion. DG
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Post by imperfectgolfer on Nov 28, 2018 14:51:34 GMT -5
Dr Mann Just found this pdf from Koike which imho shows clearer graphs (with golf swing avatars linked to parts of the graph). ojs.ub.uni-konstanz.de/cpa/article/download/6828/6125Graph b Quite interesting because it seems to show (if I've interpreted this correctly) that this golfer was not pulling with his right hand/arm through the shaft Y axis of the club. In fact it seems like the right hand was actually resisting the pull of the left hand in some constant fashion virtually throughout the downswing but then slightly less from P6 -P7. The downswing pull down the Y axis of the shaft is virtually all left hand with a greater rate of increase from release into impact (but quite a smooth curve). Graph c Again (if I've interpreted this correctly) , the right hand involvement in PA3 release around Z axis seems to be greater than left hand from around P6 and maximising torque around P6.3 and decreasing to zero around P7. Graph a It seems that the left hand is retarding PA2 release while right hand promoting PA2 release (in the x-axis at any instantaneous moment). But that the right hand force in the x-axis is always slightly larger which means PA2 release is actually occurring (albeit in small amounts up to release) from P4 . I'm not an expert in deciphering graphs so maybe you can provide a better opinion. DG That Koike paper is new to me. Here are the graphs from that paper. I only had the instrumented handle paper - here are the graphs from that paper. Why are the graphs for the Y axis so different. I have no idea how to interpret these Y graphs! Jeff.
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Post by dubiousgolfer on Nov 30, 2018 19:24:05 GMT -5
Dr Mann I have read a few of these papers but find them generally difficult to follow because he uses his own terminology rather than TGM. Unsure about this 'snip' method used to analyse golf swings because there might be subtle but important biomechanical moves not identified within the 'snip'. Interesting concept about DSI planes (and the different ways golfers transition into this plane) but uncertain whether he has any scientific evidence to support this concept although I have read Tutelman's article regarding stability of swing plane (which indeed suggests ways of creating stability in a 'functional plane' for a particular combination of different variables ). www.tutelman.com/golf/swing/stability.phpAlso found his analysis of the 'inflicted curse' quite interesting and sort of reminds me of the reasoning behind 'set-up for impact'/One Plane' swing that Kirk Junge and Todd Graves advocate. Will you be doing any critical reviews of these papers? DG I have not yet started to read all his articles because I am busy writing a review paper on Tyler Ferrell's "Stock Tour Swing" ideology. I should complete that review paper in 10-14 days and then I will start to study Ben Allen's work. I will only write a review paper on his work if I think that it is worthy of serious intellectual analysis. Jeff. Dr Mann If you do decide that Ben Allen's work is worthy of serious intellectual analysis , I can forward you the email that he has sent to me below (one of the attachments is too large to be added in this post). I've had a quick look at the attachments and, to be honest, found it very difficult to follow (especially the sentence I bolded/underlined below) -------------------------------------------------- "I very much appreciate your email and comments. I hope you will challenge me on anything that does not seem to be supported by the snips evidence. I work with John Gerring, a PGA Hall of Fame member, to develop the discussions about any particular swing question. The benefit has been that we have been able to bridge the gap between my experience in graphic analysis and his extensive work on teaching the swing and personal acquaintance with major tournament players over the past 60 years or so. Golf players and rentiers lack any workable knowledge of STEM subjects; so looking at pictures enables otherwise impossible conversations. I have attached 2 documents that should spare you the drudgery of working through my online posts at academia.edu. From a theoretical perspective, in my assessment, Harry Vardon had the most efficient swing mechanics of any golfer I have studied. He avoided body action to a great extent and used a roll-through-impact tactic, although he made no comment on swing mechanics. The radius of club head path through impact is significantly shorter with roll-through compared with other tactics like square-to-square - about 40% shorter Jack Nicklaus vs. JB Holmes. That high-speed video recording, 3000-6000 fps, has made it possible to make or confirm shaft deformations by reducing the possibility of focal plane distortion for misleading, confusing snips data. My intent is to provoke thought by projecting what John and I agree on and to make the point that most of what is available to the public cannot withstand critical study. Challenge to any of our output will be welcomed. I hope you will remain engaged." ----------------------------------------- DG
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Post by imperfectgolfer on Nov 30, 2018 23:07:44 GMT -5
DG,
I cannot understand why the clubhead path radius should be shorter at impact if one rolls through impact - unless he is measuring the clubhead path between P7 and P7.2 which will be shorter if the clubshaft bypasses the left arm during that time period. What is the potential advantage of having a shorter radius during the P7 and P7.2 time period due to either left forearm supination, or left wrist flipping, during that time period?
Jeff.
p.s. Please forward that e-mail to me at jeffmanngolfer@gmail.com
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Post by utahgolfer on Sept 8, 2019 21:22:34 GMT -5
Power is the product of force x speed. Speed is often talked about but differences in force output potential between males and females is probably what explains driving distance (power) differences between the genders. More absolute muscle mass across the entire body likely gives males the power advantage. Speed is probably more of a function of motor control (coordination) and muscle fiber type (fast or slow twitch), which males and females are likely more similar. (Although fast twitch fibers are good at both force output and speed output.)
In swinging a bat, a weaker person must swing a bat with less mass so they can generate the necessary force to move the bat at an optimal speed. Using a bat that is too heavy would decrease power output since the person's force potential could not move the bat at an optimal speed. Using a bat that is too light would also not produce optimal power since the force variable would be under-utilized. To optimize power output, a person needs to swing a bat that has the right mass for that individual person. And, this bat comparison would clearly show that men would use a much heavier bat due to more absolute muscle mass, while women would use a much lighter bat. What is interesting is that the female batter might swing their bat at the same speed as the male batter, but have significantly less swing power since they are unable to move a heavier bat at the same speed as the men, or at a faster speed sufficient to negate the force output differences.
A loaded freight train exhibits much more power than an unloaded train moving at the same speed. A baseball bat could move at the same speed as the freight train but wouldn't create much of an impact compared to the train. Both force and speed matter.
In golf, the club weight between men and women is relatively small, but it could make a significant difference. I assume club weight differences would correlate highly with driving distance. Those with less force output potential would never want to swing a heavy golf club, and vice versa. Also, I assume shaft stiffness depends on optimal power output, in that both the mass of the club and the swing speed both influence optimal shaft stiffness.
Another force variable is stabilization of the club through impact. I assume men have a more optimal stabilization of the club at impact due to more muscle mass, allowing for more energy to be delivered into the ball and less energy leakage away from the ball. This probably also contributes to gender golf swing power differences.
With Iron Byron machines, it would be interesting to see how it is set up to regulate both force and speed. For example, I assume one could set the machine up as an average LPGA golfer with the same club mass and swing speed and generate driving distance averages, then do the same for the average PGA golfer. Grip forces could also be adjusted to evaluate stabilization and possible energy leaks. It would be interesting to document how both force and speed must be optimized to yield optimal power. I believe this would go a long way in understanding why men golfers hit the ball farther than women golfers.
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Post by dubiousgolfer on Sept 9, 2019 7:13:21 GMT -5
Hi Utahgolfer The physics of clubhead/ball interaction can be quite complex and counter-intuitive. Lets take the example you mentioned above regarding the loaded & unloaded freight train. If you put a golf ball in front of each train and they were both travelling at the same speed at impact , one might think that the ball would travel a lot further after collision with the loaded train. But the ball would very likely travel approx the same distance for both collisions. The collision equation is below: v2 =[(m1)/(m1 + m2)] x (1 + e) x (u1) The velocity with which the golf ball leaves the clubhead is equal to V2 mass of the clubhead =m1 mass of the ball=m2 (approx 0.046 kg) coefficient of restitution= e (a usual average value is about 0.8) velocity of the clubhead before impact = u1 If you started putting in different masses of clubhead into the above equation , you'll find that once its mass exceeds 11 pounds (0.453 kg), it has virtually no effect (less than 1%) on the initial velocity of the golf ball. Below is an extract of an article I've read and you will find that the loss of clubhead speed starts to plateau off as the clubhead mass gets larger. ------------------------------- Effect of Clubhead Mass What is the effect of the mass of the clubhead and the velocity of the clubhead on producing velocity in a golf ball? Let's examine the effect of the mass first. Inserting different weights for the clubhead, we can calculate the effect of clubhead mass (in ounces) on producing velocity. A golf ball weighs 1.68 ounces. M=6oz, M/(M+m) = 6/(6+1.68) = 6/7.68 = 0.781 78% of the mass is transferred or the velocity of the clubhead is reduced by 22%. M=7oz, 7/8.68 = 0.806 81% of the mass is transferred or the velocity of the clubhead is reduced by 19%. M=8oz, 8/9.68 = 0.826 83% of the mass is transferred or the velocity of the clubhead is reduced by 17%. M=9oz, 9/10.68 = 0.843 84% of the mass is transferred or the velocity of the clubhead is reduced by 16%. -------------------------------------- Unsure whether there is much difference in clubhead mass between PGA and LPGA players, but its more obvious to me that clubhead velocity at impact is the reason for the different distances. Probably needs more research to figure out whether strength and ratios of 'Fast twitch /Slow twitch' muscles are a factor or even the differences in the length of the lever arms (in the limbs). Tutelman wrote an article which might also be worth a read. www.tutelman.com/golf/swing/tallGolfer.phpImho , I think the PGA golfers are better able to create optimal hand speed/path than LPGA golfers. Interesting you mentioned clubface stabilisation through impact (especially for non-centre strikes ). I don't know 100% whether PGA/LPGA golfers are able to stabilise the clubface through impact and limit clubface gear affect (and spin) on the ball. All I do know is that some 'golf science' people say that the clubhead can be thought of as a free moving mass through impact and that the clubshaft can be viewed as acting as a piece of string (ie. there is not enough time for any actions done by the hands to transmit its effect down the shaft to the clubhead for the period of impact which is 1/4000 sec). As for shaft stiffness, this is what Dave Tutelman says (see 'Shaft Material' section) www.tutelman.com/golf/swing/golfSwingPhysics4.php"Note: contrary to common claims, the flex of a shaft has no effect on the club head speed, and there is little energy stored in the flex of the shaft that can be recovered at impact – this is all advertising BS. The shaft flex does however affect the loft of the club at impact." Regards DG PS. Gets even more complicated after reading this research article www.researchgate.net/publication/304203875_The_Influence_of_Clubhead_Mass_on_Clubhead_and_Golf_Ball_KinematicsConclusions This study has provided novel insights into the understanding of how the mass of a driver’s clubhead influences driving performance. Increasing clubhead mass within a commercially available range was found to decrease clubhead speed, but have no meaningful influence on ball speed. Similarly, increasing clubhead mass had clear influences on dynamic loft, angle of attack, and spin, but there was no net influence on carry distance and only a relatively small effect on the total predicted distance. Collectively, this suggests that manipulating clubhead mass to increase driving distance is not likely a worthwhile exercise. Clubhead mass did a have a meaningful influence on where the ball finished laterally due to differences in both launch angle and spin. Increasing clubhead mass tended to create more fade spin as well as start the ball further to the right, which resulted in meaningful differences in the average lateral finish location among conditions. This finding has important implications for club fitters and manufacturers. When adjusting the clubhead center of gravity location to manipulate ball flight tendencies, it would seem important to only ‘move’ mass, while keeping the total clubhead mass constant, so as to avoid confounding mechanisms. Finally, there appears to be some evidence to suggest that golfers with higher clubhead speeds may perform more consistently with heavier clubheads.
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Post by utahgolfer on Sept 9, 2019 16:48:20 GMT -5
DG, thank you for this fine review along with supplementary readings. There's always more to learn! I'll study this and gain a better understanding of this topic!
UtahGolfer
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