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Post by nmgolfer on Jan 9, 2012 20:03:58 GMT -5
The Miura paper doesn't show only tangential forces so that is a a lie. And if MacKinsie thinks the path is the only factor needed to determine what forces and torques are required then he's wrong too... but I seriously doubt he said that.
Look its real simple... anyone that every passed high school physics can get it.... the fact that the path is curvilinear means there is a force directed inward. Un freaking believable!
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Post by imperfectgolfer on Jan 9, 2012 22:47:22 GMT -5
nmg wrote-: ""Look its real simple... anyone that every passed high school physics can get it.... the fact that the path is curvilinear means there is a force directed inward. Un freaking believable!"
Of course there is a force directed inwards if the hands move along a circular path - because the hands have to move from one instantaneous point on the circular path to the next instantaneous path on the same circular path. However, the magnitude of the inward -directed force should not have to increase (be more inward directed) if the radius of the hand arc path doesn't change.
So, going back to the SN diagram.
The red arrow shows the inward directed force at roughly the P5.5 position and the blue arrow represents the inward directed force at the P6.5 position - they should be the same in magnitude/direction if the radius of the hand arc path is the same at P6.5 compared to P5.5.
Jeff.
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Post by natep on Jan 9, 2012 23:55:50 GMT -5
OMG CP increases as hand velocity increases, even if the radius stays the same!!! If the hand velocity doubles on downswing, then the CP quadruples!
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Post by imperfectgolfer on Jan 10, 2012 0:22:15 GMT -5
Natep,
This is the best contribution that I have ever seen you make -I like it a lot.
Basically, it would imply that the CP-force (inward directed force) increases in magnitude as the downswing progresses because the hand velocity is steadily increasing (even if the hand arc path radius remains constant). I wonder whether that could explain why SN drew the arrows as being more inward-directed as the downswing progresses - presuming that the arrows represent only the CP-force component. I am still not sure what the arrows truly represent when he simply stated "force" in his presentation.
Jeff.
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Post by natep on Jan 10, 2012 0:26:31 GMT -5
Im glad you like it, but nmg's been saying the same thing since page 1 of this thread.
I havent seen the ASII video yet, so Im not positive what his arrows truly represent.
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Post by imperfectgolfer on Jan 10, 2012 0:51:50 GMT -5
Natep,
It is true that nmg stated the same fact, but I was thinking that we was using that argument to justify this statement -: "I argue the force is NEVER directed at the center of curvature (which is contantly moving... it not fixed). This is why I say we should forget the concept of parametric acceleration because it implies something different happens in the last stages before impact. NO! Parametric acceleration is happening throughout the last two of three stages of the ds."
I don't think of parametric acceleration as simply happening in the last two of three stages of the downswing. I think of parametric acceleration as being due to a significant tightening of the hub radius between P6.6 and P7 due to a pulling-up of the grip end of the club (linear actuator in action in the Miura model) .
You got through to me because you isolated the same equation independent of any argument relating to parametric acceleration, which made me suddenly wonder whether it is somehow connected to those yellow arrows that he used to show the direction of the "force" - where he directed the arrows more inwardly as the downswing progresses. Interestingly, I don't recall him talking about increasing hand speed velocity in the downswing as a causal factor for him angling the yellow arrow more inwards.
Jeff.
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Post by nmgolfer on Jan 10, 2012 10:10:57 GMT -5
Im glad you like it, but nmg's been saying the same thing since page 1 of this thread. I havent seen the ASII video yet, so Im not positive what his arrows truly represent. His arrows represent "THE FORCE" which is the vector sum of all components. In 2D think: FORCE = [Ft^2 + Fr^2]^1/2 and ANGLE= arcTan(Ft/Fr) where: Ft = tangential force which is tangent to hand path Fr = radial force which points towards the instantaneous center of rotation also know as centripetal force or cp Angle ... is the angle in degrees relative to a line drawn from hands to the instantaneous center of rotation. use pythagorean theorem to calc. the magnitude of THE FORCE and close to impact the radial component is the dominant factor so the arrow point points CLOSE TO (but never directly at) the instantaneous center of rotation... that is unless the golfer is a flipper whose hands stop in which case Ft can be zero or negative. TeeAce just posted at the cesspool that the force vector is 40% off (off centrally directed) at impact. I don't buy that it is that much... but if the golfer is good and accelerates the CH clear into impact then it will definitely be an angle greater than zero. Nate ... do you see why I say it make no sense to talk about parametric acceleration as if its something only happening close to impact? This is an important point. rdgs.. PS it is sweet justice to see that the BM has adopted nearly everything I was saying back on 2007 and for which he booted me from his forum... He's just 5 years behind the times now.
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Post by gmbtempe on Jan 10, 2012 10:25:20 GMT -5
How does the radius stay the same in a golf swing?
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Post by imperfectgolfer on Jan 10, 2012 10:38:23 GMT -5
nmg suggests that the "force" (F) is the vector sum of all the components.
That could explain why the degree of inward-direction of the F increases steadily throughout the downswing - because the hands are speeding up in the mid-late downswing, and that increases the CP-force component greater due to the Fcp equation.
I could accept that explanation. However, that explanation should also allow the club to release passively (automatically) according to nmg's release principle (V clubhead = V hands + V rel). Why then does SN have to add an additional torque force that BM uses to justify his right hand applying a push-force around the coupling point starting at P5.5?
Also, this inward directed force, that that has an increasing inward-directed component as the downswing progresses does not explain the parametric acceleration phenomenon - which SN stated is due to the pulling up of the grip end of the club as the hands near impact. SN stated that he didn't draw the spiral-tightening of the radius of his hub path diagram between P6.7 and P7 on that white board to reflect this phenomenon.
Jeff.
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Post by imperfectgolfer on Jan 10, 2012 10:41:43 GMT -5
Greg,
You asked-: "How does the radius stay the same in a golf swing?"
I don't know if you are referring to the hand arc radius or clubhead arc radius. I also don't know what point you are tring to make.
Interestingly, although SN drew a circular-looking hub path on that white board at the AntiSummit II, he actually stated that the hand arc path radius decreased between P6 and P6.5 (see the area of the blue dotted section of the hand arc path).
Jeff.
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Post by gmbtempe on Jan 10, 2012 10:59:45 GMT -5
My point is you can play around and change the radius thus affecting the calculations as I see it. I am talking about both, you can change both.
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Post by imperfectgolfer on Jan 10, 2012 11:54:47 GMT -5
SN stated that his hub path model was a generalization based on the study of many golfers, and that there was great individual variablity in the shape of the hand arc path, and therefore the timing of the club release patterns.
Jeff.
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Post by imperfectgolfer on Jan 11, 2012 11:59:58 GMT -5
Look again at this photo - look at the torque graph. REMOVED Note that the torque graph peaks in the late downswing and becomes zero by impact. I can understand that a golfer can apply a torque around the coupling point to release the club as BM uses in his swing-hitting action. However, does that torque graph vary in shape and magnitude depending on the shape of the hand arc path and its resultant "club releasing" efficacy (Vclubhead = Vhands + Vrel). I have studied SN's research paper and I cannot see where he has calculated how much club releasing power occurs passively according to the nmg principle (Vclubhead = Vhands + Vrel). Surely, that amount must be deducted from the total amount of additional torque force that may be required to get the clubhead to catch up to the hands by impact. Consider a Pingman machine that is perfectly setup to square the clubface at impact and generate a clubhead speed of 1110mph at impact. How can adding any positive torque to the club release action improve things? See this Tutelman page authored by Rod White. www.tutelman.com/golf/swing/golfSwingPhysics3a.php#wristcockIn particular, consider this graph. www.tutelman.com/golf/swing/golfSwingPhysics/wristtorque1.gif [/img] He shows that the addition of any positive torque decreases clubhead speed and makes it peak before impact. Jeff.
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Post by nmgolfer on Jan 11, 2012 12:25:00 GMT -5
Torque is NOT a force! repeat TORQUE IS NOT A FORCE....
Tuttelman peddles some junk science. Rod White gets those results because they are based on a badly flawed model i.e the double pendulum. The CONTRACTING SPIRAL hand path which you think is a: "figment of my (nmgolfer's) imagination" makes it possible to add torque and increase chs at impact. Only girlyman golfers use the passive "swingers" release.
Pingman cannot be compared to a human golfer. Pingman is constrained to swing on a plane and the motor is sized to achieve any desired objective without the need for coupling point torque.
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Post by nmgolfer on Jan 11, 2012 12:32:24 GMT -5
My point is you can play around and change the radius thus affecting the calculations as I see it. I am talking about both, you can change both. Exactly... what I've been saying for years. The key is hand path and velocity along it. Strive for a spiral (I will produce a paper showing why this is the theoretical ideal some time) shape wise and start slowly then pour on the speed into impact. I don't care about how you move your body (micromoves) to accomplish that. I prefer Austin-like mobility vs. xfactor stretch-stiffness.
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