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Post by imperfectgolfer on Jul 15, 2012 9:56:24 GMT -5
Consider this BM-forum thread started by Todd. www.brianmanzella.com/golfing-discussions/17458-release-description.htmlTodd stated-: "Not sure there's a better one than this...................."Throw the clubhead off the shaft at the left foot." Two "feel" questions regarding the release action. i) Why must one "feel" that one is throwing the clubhead off the shaft? ii) Why must one "feel" that one is aiming at the left foot? What is happening biomechanically as a result of this "left foot aiming" process? Jeff.
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Post by virtuoso on Jul 17, 2012 13:10:23 GMT -5
jeff, did he mean "aiming" toward the left foot, or did he mean WHEN the club passes the left foot, as the left foot is past the ball. So, throw the clubhead off at a point past the ball?
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Post by imperfectgolfer on Jul 17, 2012 13:21:51 GMT -5
I don't know exactly what he meant - he seems to be aiming at his left foot for some reason.
Jeff.
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Post by virtuoso on Jul 17, 2012 15:15:55 GMT -5
I don't know. I think Todd is a pretty darn sharp teacher. I don't think he would want us to try to throw the head TOWARD the left foot. I believe his emphasis is on the proper amount of shaft lean at impact for the given loft. To me, that would indicate he meant timing on the release, not direction.
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Post by imperfectgolfer on Jul 17, 2012 18:17:56 GMT -5
I have no idea how you can come to that conclusion based on what he stated about "aiming at the left foot". Why don't you ask him on the BM forum?
Jeff.
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Post by imperfectgolfer on Jul 17, 2012 20:01:49 GMT -5
Virtuoso,
A friendly recommendation - I would recommend that you never mention my name in any post in BM's forum if you do not want to be banned from his forum. You should probably also not mention the NGI if you don't want to anger the BM-groupies.
Jeff.
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Post by imperfectgolfer on Jul 17, 2012 20:05:37 GMT -5
Things are heating up in that Todd-initiated BM-forum thread.
Todd wrote-: "The shaft will come off of the head when the shaft becomes vertical....they are THROWING the head off of the shaft, not PULLING the shaft off the head."
BM then wrote-: "BA-loney!"
So, what do you think is happening in a constant hub radius swing action?
Jeff.
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Post by imperfectgolfer on Jul 18, 2012 7:06:37 GMT -5
Todd is stating that the clubhead will come off the shaft when the clubshaft is vertical, and the clubhsaft becomes vertical at low point - which is very near the left foot. Maybe that is what Todd means by stating that he aims at the left foot. I think that it is better to think of aiming at low point, and the "feel" is that the clubhead will generate its maximum CF-loading force when it reaches low point, and it will "feel" that the clubhead is being thrown towards low point as result of the club releasing phenomenon. That is the mechanical basis of the SwingRite device - the device clicks when the club reaches low point if the club release phenomenon is optimised so that the CF-loading force is maximized at low point. BM believes that a golfer must pull the shaft off the clubhead by "pulling upwards with all one's might". Where does he get this BS idea? It's obviously from Nesbit/Miura and it is based on this diagram. One can obviously note that the normal force becomes operant at about P6.3 and increases to a maximum of 414Nm at impact. BM incorrectly believes that a golfer must "pull the shaft off the clubhead with all one's might" to generate this normal force, but that's nonsensical. The constant hub radius double-link model is not pulling up with all its might - it only has a torque motor that rotates the central arm. The normal force happens automatically as the club releases, and it is a reaction to the fact that the clubhead generates a CF-loading force as the club releases. There is no "pulling up" phenomenon in that double-link model, as there is no "pulling up" phenomenon in a Pingman machine (or any other type of club-testing machine whose design-basis is the double-link swing model). Here is an unedited quote regarding the normal force from Nesbit's paper-: "During phase I, the majority of the force is tangent to the path and primarily functions to accelerate the club. ------ During phase III the tangential force drops toward zero while the normal force increases to maximum values at ball contact. The primary action of the linear force during this phase is controlling the path and reacting to the large centrifugal loading from the club as it reaches its maximum club head velocity and coincident minimum hub radius". Jeff.
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Post by virtuoso on Jul 18, 2012 10:08:09 GMT -5
Oh, ok, I misunderstood. I thought the centripetal force was applied to the system by the golfer merely hanging on the the club as his arms swing the club in an orbit and cf-loading was the equal and opposite newtonian reaction to that.
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Post by virtuoso on Jul 18, 2012 10:29:12 GMT -5
Virtuoso, A friendly recommendation - I would recommend that you never mention my name in any post in BM's forum if you do not want to be banned from his forum. You should probably also not mention the NGI if you don't want to anger the BM-groupies. Jeff. Thanks, but i don't think the other BM-groupies even care what we are talking about over here. It's only you, me and about 5 other monkeys.
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Post by imperfectgolfer on Jul 18, 2012 18:11:14 GMT -5
I know that the BM-groupies don't care about our discussion here at NGI. However, I don't want to see you get banned from BM's forum because of any association with me (on any level).
By the way, you are not exactly my idea of a BM-groupie - because you seem to be willing to intellectually explore alternative non-BM ways of thinking about golf swing mechanics/biomechanics and you are not willing to automatically swallow BM's "koolaid" without independent thinking.
Jeff.
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Post by imperfectgolfer on Jul 18, 2012 18:18:18 GMT -5
Virtuoso,
You wrote-: "I thought the centripetal force was applied to the system by the golfer merely hanging on the the club as his arms swing the club in an orbit and cf-loading was the equal and opposite newtonian reaction to that."
It's the other way around. If one swings one's arms without a golf club (that can produce a CF-loading force) then there is no need for a normal force to maintain the hand arc path. The presence of a CF-loading force means that a golfer must apply a normal force to counterbalance that CF-loading force so that he can maintain the constant radius hand arc path unchanged. To shorten the hand arc radius between P6.5 and P7 (and thereby produce the parametric acceleration phenomenon) requires an even greater magnitude of normal force.
Jeff.
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Post by virtuoso on Jul 18, 2012 18:36:32 GMT -5
Oh, ok, but I can actually create a decent amount of cf loading without a club. If I relax my arms and then spin my shoulders back and forth, my arms will start to out stretch and I can feel the cf-load at my shoulder sockets. I can also feel the blood rush out to my hands.
So, I'm first generating a centripetal force on my arms merely because they are attached to my shoulders as they spin. The pulling/stretching sensation i feel is the cf-loading...which is the equal and opposite force to the applied cp force.
So, the cf only happens if I apply the cp first, no?
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Post by imperfectgolfer on Jul 18, 2012 18:52:27 GMT -5
I think that you are correct to infer that if you extend your left arm out at a certain angle away from your body, and then spin your torso in a circle, thereby creating a circular left hand arc path of a constant radius that the left arm/hand will exert a CF-loading force (because they have mass and a speed of motion), and you will then need to react to the CF-loading force by exerting a normal force to counterbalance the CF-loading force. If you then add more CF-loading force by adding a club, then you will need even more normal force.
In my mind, when thinking of the golf swing and "normal forces", I tend to think of the straight left arm/hand as a passive lever that simply connects the CF-load to the body (which must produce the counterbalancing normal force). It is a simpler mental model (like Miura's double-link double pendulum model) that is practically useful.
I think that one doesn't have to think of a CP-force first - if there is no object (having mass and rotational velocity) that first represents a CF-loading force because it follows a circular path.
Jeff.
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Post by imperfectgolfer on Jul 18, 2012 23:08:55 GMT -5
What do you mean by the phrase "lifting with the wrists through impact"? Please explain the biomechanics and purpose of lifting with the wrists through impact.
Jeff.
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