The hand arc is not as circular as the clubhead path.
The only time that the hand arc can be circular is a swing where the left shoulder socket remains stationary in space - as demonstrated with that double pendulum swing model where the fulcrum remains stationary (and as seen in an Iron Byron machine).
A poor golfer may have a near-circular hand arc if he accelerates the hands from the top of the swing and starts the kinetic sequence incorrectly with a hand pull down motion.
Good golfers start the downswing with a lower body shift movement that causes secondary axis tilt => they then rotate the right shoulder downplane => that allows the left arm to be pulled down to the ball (via the release of PA#4) along an inside track. That produces an U-shaped hand arc - as demonstrated in this next photo of Tiger Woods hand arc.
The upper portion of the hand arc is very "straightish" and that doesn't induce a release phenomenon. The release phenomenon doesn't only depend on the radius of the hand arc curve; it also depends on the hand speed as it moves through that portion of the hand arc curve. Tiger's hands aren't moving very fast during the "straightish" portion of the U-shaped hand arc because he hasn't yet released PA#4. The speed of hand movement in the early downswing is determined by the speed of the pivot rotation - because the left arm is still kept across the chest wall (PA#4 remains loaded) and the power package is kept intact.
Tiger's hand speed becomes maximum when PA#4 is released and that happens when his hands are going around the bottom of the U-shaped hand arc. That means that his hand speed is maximum when the radius of the hand arc curve is smallest (tightest rounded curve) and that causes the passive release of the club. Although we commonly refer to this release as a centrifugal-induced release, a better explanation is nm golfer's mathematical explanation. Either way, the release is passive, and the "force" inducing the release is the circular motion of the fast-moving hands.
KOC - I do believe in 10-23-A - see above photo of Tiger Woods. I simply use the term 'straightish" because the hand arc can never be perfectly straight. However, it can be close to straight if the kinetic sequencing is correct. To prevent a circular hand arc path that promotes a sweep release, a golfer needs to induce a more U-shaped hand arc (like Tiger Woods) by making sure that the thrust-direction of the hands is in a straight line direction towards a desired aiming point (eg. ball or point ahead of the ball on the ball-target line) and the kinetic sequence is optimised.
The hand arc is not as circular as the clubhead path.
The only time that the hand arc can be circular is a swing where the left shoulder socket remains stationary in space - as demonstrated with that double pendulum swing model where the fulcrum remains stationary (and as seen in an Iron Byron machine).
A poor golfer may have a near-circular hand arc if he accelerates the hands from the top of the swing and starts the kinetic sequence incorrectly with a hand pull down motion.
Good golfers start the downswing with a lower body shift movement that causes secondary axis tilt => they then rotate the right shoulder downplane => that allows the left arm to be pulled down to the ball (via the release of PA#4) along an inside track. That produces an U-shaped hand arc - as demonstrated in this next photo of Tiger Woods hand arc.
The upper portion of the hand arc is very "straightish" and that doesn't induce a release phenomenon. The release phenomenon doesn't only depend on the radius of the hand arc curve; it also depends on the hand speed as it moves through that portion of the hand arc curve. Tiger's hands aren't moving very fast during the "straightish" portion of the U-shaped hand arc because he hasn't yet released PA#4. The speed of hand movement in the early downswing is determined by the speed of the pivot rotation - because the left arm is still kept across the chest wall (PA#4 remains loaded) and the power package is kept intact.
Tiger's hand speed becomes maximum when PA#4 is released and that happens when his hands are going around the bottom of the U-shaped hand arc. That means that his hand speed is maximum when the radius of the hand arc curve is smallest (tightest rounded curve) and that causes the passive release of the club. Although we commonly refer to this release as a centrifugal-induced release, a better explanation is nm golfer's mathematical explanation. Either way, the release is passive, and the "force" inducing the release is the circular motion of the fast-moving hands.
KOC - I do believe in 10-23-A - see above photo of Tiger Woods. I simply use the term 'straightish" because the hand arc can never be perfectly straight. However, it can be close to straight if the kinetic sequencing is correct. To prevent a circular hand arc path that promotes a sweep release, a golfer needs to induce a more U-shaped hand arc (like Tiger Woods) by making sure that the thrust-direction of the hands is in a straight line direction towards a desired aiming point (eg. ball or point ahead of the ball on the ball-target line) and the kinetic sequence is optimised.
Jeff.
I appreciate your efforts in making your points with pictures. But, perspective is so important. Pictures of planes are not valid, unless the camera is 'looking' on plane. Pictures of circles are not valid, unless the camera is 'looking' squarely at the face of the plane.
Measuring a radius of a circle from an oblique camera angle can give you an invalid reading. Any measurement of the hand of a clock should be taken when facing the clock. It should not be measured in a 2-D picture taken from the side.
You wrote-: "Measuring a radius of a circle from an oblique camera angle can give you an invalid reading. Any measurement of the hand of a clock should be taken when facing the clock."
That's perfectly correct. I am presuming that all readers understand that all my photographs are only representative - that they are 2-D images of 3-D motions, and that there will be perspective distortion due to an imperfect camera angle relative to the relevant clubshaft/hand plane. However, I do not believe that the fundamental principles that I am attempting to demonstrate are incorrect - because of these camera angle problems. For example, the clubhead arc of Tiger Woods driver swing (from the Nike commercial) is obviously distorted because the camera angle is face-on - while the clubead arc motion is on the inclined plane. However, it remains a "fact" that the radius of the clubhead arc (relative to the swing center) is very different at different time points during the downswing and followthrough, and that the swing center cannot be conceived to be the dead-center of a circle of the clubhead arc's rotational arc motion in space. The same "fact" applies to Tiger's hand arc photo - it is only representative because the camera angle is not perpendicular to the hand arc's circular arc of motion in space.
You wrote-: "Measuring a radius of a circle from an oblique camera angle can give you an invalid reading. Any measurement of the hand of a clock should be taken when facing the clock."
That's perfectly correct. I am presuming that all readers understand that all my photographs are only representative - that they are 2-D images of 3-D motions, and that there will be perspective distortion due to an imperfect camera angle relative to the relevant clubshaft/hand plane. However, I do not believe that the fundamental principles that I am attempting to demonstrate are incorrect - because of these camera angle problems. For example, the clubhead arc of Tiger Woods driver swing (from the Nike commercial) is obviously distorted because the camera angle is face-on - while the clubead arc motion is on the inclined plane. However, it remains a "fact" that the radius of the clubhead arc (relative to the swing center) is very different at different time points during the downswing and followthrough, and that the swing center cannot be conceived to be the dead-center of a circle of the clubhead arc's rotational arc motion in space. The same "fact" applies to Tiger's hand arc photo - it is only representative because the camera angle is not perpendicular to the hand arc's circular arc of motion in space.
Jeff.
The picture on the cover of Search for the Perfect Swing is a good series of time-elapsed photos. The picture's also found in Chapter 3, with explanations. It's a worthwhile read.
When you wrote: "The hand arc is not as circular as the clubhead path."
I don't know how you can arrive at such a conclusion, with or without faulty camera angles.
Let's make the geometry simple, if anyone else is going to learn anything. And, we'll consider the center of the circle the left shoulder, since it's the top of the radius. Let's call the left shoulder "A". We'll call the hands "B" and the clubhead "C".
Scenario #1, Hands:
If the distance between "A" and "B" remains somewhat constant (Extensor Action), "B" should inscribe a circle on a piece of paper, like a compass. If we complicate it by letting "A" move (like the golf stroke), the circle becomes somewhat elliptical.
Scenario #2, Clubhead:
If we measure the distance between "A" and "C", we have to consider the cocking and uncocking of the left wrist (shortening and lengthening of the radius).
Hybrid Mode
