Joe Mama

For readers who may have joined this thread only recently, and have read only recent posts, they may be under the impression that I am defending the proposition that golf balls are driven toward the ground following a strike by the iron. Let me say that I've never stated, nor have I ever implied in a post, that such was the case. All videos I know about do not show the so-called "pinching" or "trapping'," or compression of the ball against the ground, and I've never seen a golf-ball size crater in photos of Tiger's near-perfect divots. I have presented what I believe is a correct analysis based on force vectors and their components, and Newton's Second Law, and demonstrated that the golf ball-clubface interface would have to have an improbably high coefficient of friction in order that the ball be driven downwards. We all agree that the ball is not pinched--well, most of us. What we seem not yet to agree on is whether my force diagram and subsequent derivation of the "tangent" equation is correct. I have further claimed that iacas left off one of the forces acting on the ball when he presented his force diagram. Does he still believe that the frictional force does not belong in the diagram? If he agrees it SHOULD have been shown, why was it omitted in his drawing? Based on what he learned in the many physics classes he has taken, does he find fault with my derivation of the tangent equation, which shows that, theoretically, with a large enough coefficient, the ball WOULD be driven downward?

Place a ball on the floor and apply a sideways (tangential) force to it, perhaps by brushing along its side with your foot. Does it rotate? Does it also translate (move forward)? The frictional force on the golf ball is responsible for the torque that rotates the ball, and that force would, if there were not a competing force, cause the ball to translate (move downward). In every realistic situation involving our golf ball the competing force wins, and the ball moves upward. That we all agree on. What some of us don't agree with is the force diagram iacas presented. We need to wait to hear from him if he wishes to defend it.

I am still waiting for someone to explain the flaws in my diagram. Have I incorrectly represented the forces. Did I apply Newton's Second Law incorrectly? Iacas? I respect your opinion regarding physics, since you earlier responded to a challenge from a poster in this thread (Augusta Hacker) to you to study Newton's Laws: You wrote, "I probably took a lot more physics classes than you. I don't need to re-read Newton's Laws of Motion in order to debate someone who seemingly forgot some of what he learned in Physics 101." I hope my analysis won't similarly lead you to believe I forgot what I learned in high school. Maybe I haven't taken a lot of physics courses as you, but I still stand by my conclusions, so far. Did I forget something, or did you?

All that is necessary for kinetic friction to exist is for RELATIVE motion between ball and club face to occur. For example, if you snap the tablecloth off the table, the cups and saucers remain stationary. In such a case, kinetic friction is acting on the saucers. There is relative motion between ball and clubface as the face moves downward and the ball either slides or rolls up the face, or in the extremely unlikely case I described, also moving downward. For this reason, it is proper to speaking the kinetic friction acting on the ball.

The drawing above shows the two forces (ignoring the gravitational force) acting on the golf ball at impact. One of the forces is the normal force (call it N) and the other (the one omitted by iacas) is the frictional force (call it f). Let @ represent the angle theta, and k the coefficient of kinetic friction. The sum of the y-component of those two forces is given below: N sin @ - kN cos @ If this sum is negative, there will be a net downward force on the ball, which means the ball will be accelerated toward the ground. In order that the sum above be negative, the coefficient must be greater than the tangent of the angle @. k > tan @ In the case of a 31 degree angle, k would have to be greater than 0.6. Rare indeed are coefficients this large, and non-existence they are for golf balls. Thus, no pinching will ever be observed, but that doesn't absolve iacas of the responsibility to offer correct physics to support his view. Iacas, if my diagram and associated mathematics is in error, please explain exactly why. (Note added: f = kN)

Please explain why the "physics" in the force diagram below is wrong, iacas. The force diagram you provided in a previous post omitted the frictional force. Why did you omit it? Is DOES exist, doesn't it?

I think I explained in an earlier post that a net force downward (sum of all forces acting either upward or downward) is virtually unrealizable in a real golf setting using conforming golf balls. No golf ball that I know about has a coefficient of kinetic friction large enough to cause a net downward force that would result in the ball moving downward toward the ground. (Recall that at least a coefficient of kinetic friction greater than 0.6 is needed). Thus, I totally agree that not only is the "pinch" you describe not even "minimal" using conforming golf balls, it is not even possible. Having said that, I wish to make the point that the purpose of my post was to correct what I think is incorrect physics applied by iacas to justify his claim that no pinching occurs. He's right--as most all of us are--that no pinching occurs, but his opinion is biased by looking at videos that correctly show no pinch, as well as on his vector diagram, which is incomplete and therefore incorrect, for the reasons I gave earlier. The actual physics involved WILL allow a golf ball to be pinched, but it would have to have a coefficient of kinetic friction on the golf club face greater than 0.6. Again, I state that iacas physics is incorrect.

The arrows in your drawing don't seem to account for the fact that the ball rotates counter-clockwise, causing the ball to roll up the club face. In order that this happen, a counter-clockwise torque has to be applied to the ball. This torque would be achieved by a frictional force exerted tangentially to the ball, which you don't show. You only show the contact force (also called the normal force). The three arrows you show represent a correct "resolution" of the contact force vector (the hypotenuse of the right triangle) into its horizontal and vertical components. So far, so good. But, because there is relative motion between the clubface and the ball, with the face moving downward, sliding under the ball and the ball rolling up the face, the ball is rotating counter-clockwise UP the face. How could a counter-clockwise rotation occur without a counter-clockwise torque? It couldn't. What your drawing does not show is a fourth red arrow that accounts for the kinetic friction force vector tangent to the ball. The vertical component of the missing frictional force vector would compete against your short vertical arrow (the verticall component of the contact force). As I indicated in my discussion of the tangent equation I derived, only in the case of a pair of surfaces with an extraordinarily high coefficient of kinetic friction would the vertical component of the frictional force be greater than the vertical component of your contact force vector. In sum, I believe the fault in your analysis lies in the fact that your drawing ignores friction.

A few posters invoked laws of physics to justify their position, so I thought I would try my hand at applying highschool physics to the question of whether there ever could be a downward force acting on the ball during contact with the clubface that is greater than the upward force. The result I came up with involves the so-called "coefficient of kinetic friction," which I will symbolize as "k," and the club loft, which I will symbolize as @. In order that the ball be driven downward, the following condition must be satisfied: k > tan @ In the case of a 31 degree six iron, the coefficient would have to be larger than 0.6. A typical metal to polymer coefficient is 0.2-0.3, while steel on wood is 0.2-0.5. I don't know what the coefficient is for a typical golf ball coating and the metal clubface, but it is probably around 0.3--way too low for our purposes. However, it looks like to me the "physics" does, indeed, support an argument that a golf ball with a sufficiently large coefficient of kinetic friction on metal would be driven downward, contrary to the semi-rigorous arguments presented by some posters in this forum. The details of the derivation of the tangent equation above I will not provide. It is enough to say that anyone with some familiarity with force vectors and Newton's laws could reproduce for themself. Basically, I compared the vertical component of the contact force (normal force) acting on the ball to the downward component of the kinetic frictional force.

I gather that after a lengthy debate the question of whether the ball makes significant contact with the ground when struck by the club was answered in the negative. Couldn't the issue have been resolved more quickly by observing divots? I don't recall ever seeing divots with craters the diameter of golf balls embedded in them. Tiger's divots are all dollar-bill shaped rectangle of nearly uniform depth.

There is no doubt that choking down changes the "swing weight" of a club. Swing weight is basically the torque applied to the club by Earth's pull (I.e., the club's weight) relative to, say, the butt end of the shaft, when the shaft is horizontal near the top of the backswing. This torque is calculated by multiplying the club's weight by the distance between the butt end of the shaft to the "balance point" (the center of gravity, or center of mass). The balance point may easily be determined experimentally by finding the point at which the club may be balanced atop your outstretched index finger. The balance point of a typical driver is approximately 30 inches from the butt end. The "fulcrum," about about which the club will rotate, is close to the end of the shaft, so the swing weight (in relative units) is about 30W, where W is the weight of the club. If the hands are moved two inches closer to the balance point, the new swing weight would be 28W, which amounts to a percentage decrease of about 6.7%. With a smaller swing weight, less torque is needed to raise the club head to the desired speed. Further help in this regard comes from the reduction in the club's rotational inertia (MOI, moment of inertia), which I estimate to be in the neighborhood of 10%. This reduction further reduces the torque needed to accelerate the club head. Taking into account both contributions, it looks like it's reasonable to suspect that choking down two inches on the driver could make a significant difference in one's ability to control the club. The gain in distance that otherwise would occur because of these two effects would be offset by a reduction in the effective swing radius, which, all other things being equal, lowers club head speed. By how much would one have to choke the driver before the effect of reduced swing radius offsets the effects of lowered swing weight and MOI, and no gain in speed is achieved?

It will make the shaft more of an extension of the left lower arm, which, no other things considered, should be a good thing, but I agree that it is an awkward way to grip the handle. It's not a reasonable explanation of why choking down works, for some. So, the question is: What reason can one offer to explain how choking down helps? It is not enough to simply say, It works for some golfers. I would like to know exactly WHY it works. Here's Anthony Kim: Does it work because the choked club feels lighter at the top because the center of mass is closer to the hinge axis at the wrists? Does it work because the rotational inertia of the choked club is less by an amount that actually does make a difference? Does anyone know?

A number of posters in other forums have claimed that they hit straighter and often farther when they choke down about 1.5 inches on the driver. For a total distance amounting to about 75 inches from shoulder to club face, it's hard to see why a two percent shortening of effective swing radius could make a significant difference in performance. The minuscule change in rotational (moment of) inertia couldn't account for the alleged better control, and any lie angle differences would only apply to irons. So, why does choking work (if it works)? My guess is that instead of having perhaps only 0.5 inch of the handle sticking outside the base of the left hand, there are now perhaps two inches of shaft that extend beyond the palm. The shaft is now much more easily able to nestle into the left palm's lifeline, thereby allowing the shaft to become more of an extension of the left arm. Does this seem reasonable?

I heard it said (Johnny Miller) that all good (right-handed) golfers are pronating their right arm near the time of impact. (Alternatively, you can say they are supinating their left arm; either action causes the other.) When I first started playing I tried consciously pronating my right arm, and met with mixed results. Now, three years later I'm of the opinion that good golfers don't consciously pronate; it happens automatically without thinking about it if you're correct at the top and at the transition. Instead of saying that all good golfers are pronating their right arm, I would say that it is the CLUB, not the golfer, that is doing the pronating. The club's inertia naturally torques the forearm counter-clockwise just prior to impact. Also, ending up on the right toe with the belt buckle facing the target: that's not something one should think about MAKING happen, right? I find that if I'm in good position at the top, those things happen automatically. If I try to make them happen, anything can happen. Again, it's the club's inertia that pulls the right side around onto the right toe and the buckle toward the target, in my opinion. What do others think?

I think we've all had a chance to adequately express our views. In looking ahead, I cannot see how further discussion by me will be welcomed by others in this forum, so I will devote my attention to other threads and not succumb to the temptation to comment further. Thanks to all for their participation and constructive comments.

If by "pulling the ball" you mean that I'm intentionally drawing the ball, that's not something I've ever said is happening. I'm hitting it straight, not to the left. I cannot help what sounds you hear, but I've never said or tried to imply that I've given up on improving. Quite the contrary. Do golfers who've given up on improving join golfing forums to describe their discoveries (actual or imagined)? I would not have given up on curing my OTT using the orthodox stance if I hadn't found a suitable work-around. I would relentlessly be seeking the cure. Now, you may say that my work-around is second best or worse to what you consider to be the best, but I still say that I am better today than I was last week, because of the 30 degree closed stance with ball near the right foot, three knuckle strong grip.

Congratulations on defeating your OTT. Maybe your success, in contrast to my failure, is not due to your greater perseverance, but to your comparative youth and or greater flexibility. Did you cure your OTT only after fifteen years of play, or was it after two years of playing? Are you in your seventies, too? As for my 17 handicap being an indication that my recent change (made last week) isn't working for me, please allow me to update my handicap after several more months go by. I only play 18 two or three times a month, so it will take awhile to see results that might impress you. But, at my age, it's possible other parts of my game could deteriorate in that time. Maybe by June my handicap will be 25. That won't mean, however, that other parts of my game are not "working" for me.

I now hit the ball better than I used to, so I consider myself better than I was, though I am sad to hear I won't get any better. [quote name="Ernest Jones" url="/t/78402/effortless-inside-swing-with-closed-stance#post_1080617"]With that set-up I'd be afraid to smash the hell out of my left knee with the ball and/or club. As I said though, I may be visualizing this all wrong. [/quote] You WOULD hit your left knee if you start your downswing toward the target line (toward your body's 8:00 o'clock). My swing is from 3:00 to 9:00. [quote name="Phil McGleno" url="/t/78402/effortless-inside-swing-with-closed-stance#post_1080623"]I dont think most golfers count giving up and giving in like you have done as 'success'-Are you done improving? Giving up?-So you are here for validation rather than help/discussion? [/quote] I constantly strive to improve. As I said before, I am here to share my experiences. There may be others who have had a similar experience and will say so in this forum, which could encourage others who have struggled for years with OTT to try the stance, and maybe become better than they were. That would be a good thing, in my opinion. [quote name="Abu3baid" url="/t/78402/effortless-inside-swing-with-closed-stance#post_1080628"]If this swing works for you then great! If you are happy with your level then there really shouldn't be anything that any one says to dissuade you from doing what you are doing. Someone could correct me but I think I heard of a pga player that basically played pulls, I know my boss stands closed to the target as well and plays pulls (he averages around 83 on a tough course)! Are you happy with your scoring?[/quote] I shoot lower scores than others my age (70 years) who've been playing only as long as I have (three years), so I'm happy about that. But, I want to get better; I don't want to stay at the same level, so I practice every day, but even if I never improve further, I will still continue immensely to enjoy what I believe is the best game ever played.

I asked if anyone else had experienced the same kind of success as I've had in the hope that the support of others might encourage others to try out the closed stance swing. Maybe it will work for them, too. I wasn't looking for a critique of my swing at this point. Maybe later.

It would be very crowded indeed with the ball in the standard position at center or left of center stance. I place the ball way to the right of center, near the right foot. It not easy for me to make a suitable video, but that's not a problem for me because I'm not looking for help with my swing. I offered an account of my experiences just in case others might try the closed stance swing like mine and perhaps improve their playing.

[quote name="Phil McGleno" url="/t/78402/effortless-inside-swing-with-closed-stance#post_1080583"]Sounds like you come way over the top-Instead of just having a better swing you are cheating it by hitting major pulls. Edit: Bill beat me to it.[/quote] I have struggled with OTT for all of the (three +) years I've been playing. Based on the hundreds of posts on this and other forums, I would guess that 90% of high-cappers have varying degrees of OTT problems. If it were easy to fix, we'd never mention it. Rather than fighting what--for most--is evidently an un-winnable war, I've chosen an easier way out. It works for me better than any of the hundreds of trials and error compensating swings I've tried. Maybe it will work for other hackers like me--golfers who cannot for different reasons do it the "right" way. I cannot imagine, however that any pro or semi-pro or other low handicappers would benefit from such a swing.

I use a strong grip, with three knuckles of the left hand visible, my left thumb at the top right side of the shaft, 90% covered by my right heel pad. I tend to mis-hit my short irons with the standard open stance (left foot back one inch, flared left five degrees, right foot square) unless I take the club back inside and swing down along the 4:00-10:00 direction (instead of along 3:00-9:00). Too often, however, I take it back too far inside, or not enough. Looking for a simpler way to make the inside-outside-inside swing--one that requires less thinking, I started taking the same stance, but with my body closed about 30 degrees relative to the target line. The club face is square to the target line, which is now my 8:00 direction because of my one-hour twist clockwise. The ball is right if center. If I make a natural swing straight back toward my 3:00, and then through toward my 9:00, making sure going back to keep the face square to the target line (facing my 8:00) for as long as possible, I make consistently great strikes with less thought, and with fewer errors. Has anyone else had a similar experience?

If the only cause of sending the ball to the left, or right, is the direction of the face at setup, then nobody would have a problem seeing what the face angle is and knowing what to do about it, I agree. No physics or advanced math is necessary in that case. But, as I've argued in previous posts, forearm rotation--too much, or too little, depending on the lie, is also a factor.

Golfing to me is not just about making great swings and shooting low scores. I want to know, for example, WHY the ball curves one way or the other, depending on spin direction. It's not enough for me to memorize that under-spin causes the ball to lift, for example. I needed to discover how and why the air pressure above the ball is lower than the air pressure above the ball. I enjoy thinking about these things; indeed, I will "over-think" about them until I think I know exactly what is happening and why. To me, it's better to know WHY, then to just learn a rule. It is very empowering. Learning the rules regarding the dynamics of golf, rather than learning the underlying physics, is probably the best way to go for most players, including pros. If the player addressing a side-lie has to think about not only the normal things such as stance and grip and swing direction, but also about WHY the ball is sent left when the ball is below his feet, he's mind will become too cluttered to allow him to perform well. There's nothing wrong with cluttering your mind with such thoughts on the range, or on a golf forum, but on the course, just relax and obey the simple rules that you've learned through study and practice. Sometimes on the course, as I'm about to apply a simple rule, I realize I have forgotten WHY I embrace that rule. Oh, no. Do I have the rule backwards? Am I supposed to aim left, or right, when the ball is above my feet? If I have the ability to determine on the spot the answer through pure logical reasoning, am I not better off than one who is relying on memory alone?

I am a four knuckle strong grip, maintain- square- to- the -arc -as -long -as- possible golfer, it's true. I do want to roll my forearms going back or coming down. My concern with balls above or below the feet is that I have to work harder to prevent rolling in clockwise in the one case, and counter-clockwise in the other. Putting that aside, at least one forum contributor has spoken of the lie angle as being one of (if not the ONLY) culprit responsible for balls flying left when they're above the feet, and vice-versa for balls below the feet. I agree that lie angle influences ball flight, course, and further agree that when the ball is above your feet, a properly soled iron face points left, and ice-versa for balls below your feet. I performed a simple test by taping a tee to the faces of a lob wedge and a five iron, and soled each above my feet. For the lob wedge, the face points left by an observable amount, but for a much lower lofted club, such as a five iron, the face direction differs too little from square to be observed. So, I agree the lie angle influences ball direction, but cannot there be TWO causes of the ball sailing to the left when the ball is above the feet? I've suggested that when you swing at a ball above your feet, the right forearm has a NATURAL tendency to roll over the left forearm SOONER than it does for a normal lie, and this leads to an earlier closing than normal, which sends the ball to the left. This is NOT to say that the club face is not pointing left a little at setup; it is. This alone would tend to send the ball left. But, I believe it's also true that excessive arm rolling, alone, likewise would tend to send the ball left. Why cannot we believe that both effects occur? And that one effect may dominate over the other, depending on lie angle and club loft? You can test the right forearm rolling claim by swinging an iron in a horizontal plane with relaxed arms. Do you find that there is a greater tendency for the right forarm to roll over the left than in the case where you swing in a nearly vertical plane? Butch Harmon on the web page cited in a previous post attributes the ball's flight to the right--when the ball is below the feet--to a swing plane that is too upright. The implication is that there is less right forearm rotation than usual. His view, it seems to me, is exactly what I'm expressing. Are there ANY forum readers who believe, as I do, that the forearm-rolling (too much, or too little) effect, caused by the ball above, or below the feet, is ALSO a cause of the ball's flight being to the left, or to the right? Or, am I alone in my belief? Is there any agreement among members that the lie angle effect is greater for higher-lofted clubs, and less for lower lofted ones?