I’m hoping those of you better versed in the physics of golf can help clear some questions about D’Alembert’s Principle and the Release. The way I understood the principle is that the club releases because the center of mass is trying to line up with the direction of force, ergo a curved hand path is what releases the club.
Now a few questions: 1. Does the D’Alembert’s Principle apply to the release of PA#3 as well as PA#2? Or is an intentional counterclockwise move of both forearms required to release PA#3? 2. Let’s imagine a golfer who pulls the arms down in a straight line to get more lag but flips before impact. Is it because the hands make a sudden brake / change direction before contact that causes the flip to occur?
Post by dubiousgolfer on Aug 18, 2019 18:28:59 GMT -5
I think Dr Mann will be better positioned to answer some of your questions but here is my tenuous opinion.
1. D'Alembert's principle is a mathematical way of simplifying a complex dynamics problem to a statics one. Are there forces across the club (not in line with its COM) when PA#3 is released? There probably is but until someone can build force sensors in the grip handle ('or/and' in the gloves) to measure them (and any accompanied 'moments of force') , it cannot be 100% verified exactly what is happening at grip level.
As far as I am aware from reading some of Dr Manns articles, PA#3 is a club squaring action and not one that can increase clubhead speed. It requires rotation of the forearms unless the golfer (like Jamie Sadlowski) has a very strong grip. I think any rotation of the forearms would need to be passive rather than actively rotated otherwise this would mean creating tension which would hamper a natural release. Also overactive rotation of the forearms could cause non-optimal hand release actions which would require exceptional timing to square the clubface by impact.
There is also something called the 'Ryke Effect' that may aid clubface squaring by impact and I strongly urge you to seek out the you-tube videos that Kevin Ryan has published. Kevin Ryan has yet to prove whether the 'Ryke Effect' is being used by pga pro golfers and we are awaiting for the publication of his book.
2. If the golfer flips before impact after retaining lag from P4 to 'Release' point (while not applying any active wrist torques), then I can only suspect he has stalled the speed of his hands along its hub path and allowed the clubhead to bypass his hands by impact.
The most likely cause for the stalled hands is a stalled pivot.
Post by imperfectgolfer on Aug 19, 2019 9:17:43 GMT -5
Now a few questions:
1. Does the D’Alembert’s Principle apply to the release of PA#3 as well as PA#2? Or is an intentional counterclockwise move of both forearms required to release PA#3?
No! The D'Alembert principle, as explained by nmgolfer ( nmgolfscience.tripod.com/release.htm ) only applies to the release of PA#2. The release of PA#2 occurs with in the plane of the intact LAFW, which is also the plane of left wrist radial => ulnar deviation, and it occurs passively in a TGM swinger according to the laws of physics. The release of PA#3 happens in the later downswing as the entire intact LAFW rotates counterclockwise (while PA#2 is still being released) so that the clubface can be squared by impact. The release of PA#3 is biomechanically due to left forearm supination and it mainly happens passively and unconsciously in a TGM swinger. A golfer can synergistically modulate the release of PA#3 by controlling the rate of right forearm pronation - presuming that he is applying a finite amount of push-pressure with his right palm against PP#1. However, it is not obligatory to use the right forearm in that manner. The RYKE phenomenon makes it biomechanically easier to rotate the left forearm counterclockwise, but it's true importance in a TGM swinging action is unknown.
2. Let’s imagine a golfer who pulls the arms down in a straight line to get more lag but flips before impact. Is it because the hands make a sudden brake / change direction before contact that causes the flip to occur?
Yes. Flipping pre-impact is often due to left arm stalling, but it can also be due to an over-active right elbow and right wrist straightening action that causes the right hand to apply to much push-pressure against the aft side of the club handle below the coupling point.