trail arm thrust

[mandrin]

Figs 1 to 3 show the decomposition of the trail arm thrust into a wrist torque on the butt end of the handle and a lead shoulder torque. Figs 4 and 5 shows this equivalence more neatly.

In a mathematical model there is hence much less apparent difference between a hitter and a swinger. For a real golfer however there is a very clear difference.

 

[mandrin]

If we take somewhat arbitrary F=80 N, L=1 m, d=.05 m and we assume that the thrust F is always perpendicular to the lead arm we can depict the equivalent wrist and shoulder torque as shown above.

There is only a wrist torque developing when the club starts more being in line with the lead arm closer to impact. This is desirable as it is the only time when a wrist torque can add clubhead velocity.

 

[rundmc]

Mandrin . . . Do you have any data on what the torque numbers would be if the Left Wrist is bent during impact and separation?

What conclusions should be drawn on the first post for those that have not achieved their G.E.D.?

Holla fo a $.

 

[mandrin]

Mandrin . . . Do you have any data on what the torque numbers would be if the Left Wrist is bent during impact and separation?

What conclusions should be drawn on the first post for those that have not achieved their G.E.D.?

Holla fo a $.

rundmc, we are making progress, being able to write ‘mandrin’ correctly. Also through you I will with time become an expert in American slang expressions. Have you thought about this forum having an international audience not familiar with your rather ‘colloquial’ expressions?

The impact lasts for about 0.0005 s and let’s take the downswing to last about 0.3 s. Your question about impact is certainly interesting but for the moment I only cover (0.3 - 0.0005) s = 0.2995 s, or 99.83 % of the downswing. Over the next 27 years I will try to explore the remaining 0.17 % a bit more in depth.

Your second question. If we assume a stable pivot somewhere in the neck area than the first post is simply saying that, due to checkrein action, hitting and swinging are very similar from the point of view of a mathematical model.

It also shows that if you keep the point of application of the trail side thrust to be the trail heel pad and/or a perpendicular trail side thrust onto the lead arm, none or very little ‘wrist’ torque is generated to open up prematurely the lead arm / shaft angle.

However if the point of application of the trail side thrust is more towards the index finger and you keep the thrust reasonable perpendicular to the lead arm you get an useful ‘wrist’ torque, only when desirable, i.e., just prior to and through impact.

It is also very interesting for golfers with flexible wrists, obtaining less than 90 deg lead arm / shaft angle, since they can produce an angle retaining ‘wrist’ torque in the downswing, without any retaining effort, simply by an appropriate directed trail side pushing action.

There is always a general aspect, important to me, and I am sure to many golfers, and that is to simply try develop a better understanding. It makes golf definitely more fun. Few scientists are seemingly interested. Perhaps seeing the ‘warm reception’ on forums, they save their efforts for other and better activities.

 

[rundmc]

It also shows that if you keep the point of application of the trail side thrust to be the trail heel pad and/or a perpendicular trail side thrust onto the lead arm, none or very little ‘wrist’ torque is generated to open up prematurely the lead arm / shaft angle.

However if the point of application of the trail side thrust is more towards the index finger and you keep the thrust reasonable perpendicular to the lead arm you get an useful ‘wrist’ torque, only when desirable, i.e., just prior to and through impact.

It is also very interesting for golfers with flexible wrists, obtaining less than 90 deg lead arm / shaft angle, since they can produce an angle retaining ‘wrist’ torque in the downswing, without any retaining effort, simply by an appropriate directed trail side pushing action.

Interesting . . . when making the distinction between the "trial side thrust" being applied via the heel pad vs. the index finger, where exactly does the thrust come from? Pivot or an out and out push of the trail arm? Or both? Is the source of the thrust different for the different points of application?

I'll lay off the "colloquialisms" . . . see you at the G-8 Summit.

 

[strav]

Colloquialisms

Interesting . . .
I'll lay off the "colloquialisms" . . . .

Rundmc. Please don't. As a member of the international audience, I for one, would love to hear them!

 

[mandrin]

Interesting . . . when making the distinction between the "trial side thrust" being applied via the heel pad vs. the index finger, where exactly does the thrust come from? Pivot or an out and out push of the trail arm? Or both? Is the source of the thrust different for the different points of application?

I'll lay off the "colloquialisms" . . . see you at the G-8 Summit.

rundmc,

A torque at B sets the whole ensemble, ‘ABCDE’ into motion. There will be dynamic inertial torques generated due to this rotation around B. Initially there will be bending of the shaft followed by centrifugal forces dominating. This leads to a varying inertial force at E.

We are however here more concerned with the direct application of thrust at E. The thrust at E is created by either a torque at A or an extension action between A and E, or more likely, a combination of both. (For completeness one could further consider a trail hand torque.)

 

[rundmc]

rundmc,

A torque at B sets the whole ensemble, ‘ABCDE’ into motion. There will be dynamic inertial torques generated due to this rotation around B. Initially there will be bending of the shaft followed by centrifugal forces dominating. This leads to a varying inertial force at E.

We are however here more concerned with the direct application of thrust at E. The thrust at E is created by either a torque at A or an extension action between A and E, or more likely, a combination of both. (For completeness one could further consider a trail hand torque.)

Very nice . . . What body parts would equate to point E and point D?

 

[mandrin]

Very nice . . . What body parts would equate to point E and point D?

rundmc,

To alleviate response would you mind adding some flesh and bone to your question.

 

[rundmc]

rundmc,

To alleviate response would you mind adding some flesh and bone to your question.

You said "bone" uh huh . . . I would assume you are refering to the heel of the right hand and index finger of the right hand (assuming right hand golfer) with them point thingies?

 

[mandrin]

You said "bone" uh huh . . . I would assume you are refering to the heel of the right hand and index finger of the right hand (assuming right hand golfer) with them point thingies?

rundmc,

I get the feeling from your post that you take the last figure not quite the way it was meant - it does not represent just the trail side.

It represents the triangle, comprising shoulders, lead and trail arm. Hence D and E are respectively the ‘points’ where lead arm and trail arm are ‘meeting’ the shaft.

The point E represents the effective point of application of the thrust onto the shaft by the trail side. Don’t see too much complicates things. Science is often very simple.

 

[rundmc]

rundmc,

I get the feeling from your post that you take the last figure not quite the way it was meant - it does not represent just the trail side.

It represents the triangle, comprising shoulders, lead and trail arm. Hence D and E are respectively the ‘points’ where lead arm and trail arm are ‘meeting’ the shaft.

The point E represents the effective point of application of the thrust onto the shaft by the trail side. Don’t see too much complicates things. Science is often very simple.

Cool. In a prior post you said the following . . .

It also shows that if you keep the point of application of the trail side thrust to be the trail heel pad and/or a perpendicular trail side thrust onto the lead arm, none or very little ‘wrist’ torque is generated to open up prematurely the lead arm / shaft angle.

However if the point of application of the trail side thrust is more towards the index finger and you keep the thrust reasonable perpendicular to the lead arm you get an useful ‘wrist’ torque, only when desirable, i.e., just prior to and through impact.

It is also very interesting for golfers with flexible wrists, obtaining less than 90 deg lead arm / shaft angle, since they can produce an angle retaining ‘wrist’ torque in the downswing, without any retaining effort, simply by an appropriate directed trail side pushing action.

How did you measure the thrust at the heel vs. the thrust at the index finger? It seems that the index finger being the point of application is preferrable. This is good stuff. Just curious to see how the measurements at the respective points were made.

It is the thrust that generates the torque correct? And does the "acuteness" of the angles set in the lead wrist also play a role in your analysis?

 

[mandrin]

How did you measure the thrust at the heel vs. the thrust at the index finger? It seems that the index finger being the point of application is preferrable. This is good stuff. Just curious to see how the measurements at the respective points were made.

It is the thrust that generates the torque correct? And does the "acuteness" of the angles set in the lead wrist also play a role in your analysis?

rundmc,

We are not dealing with measurements but with a simple mathematical model. This is a very convenient tool and often used in science. One can play with it any desirable way, and substituting reasonable values allows to explore various options.

IMO, the most desirable point of application for the trail side thrust is not the index finger but the heel pad. You want to minimize the parameter d in post #1. Your main goal is to try keep the angle as deep as possible into the down swing.

Do the following experiment. Take a double overlap grip to minimize d as much as possible and do easy 3/4 swings. You should feel a strong tendency for the lead arm / shaft angle initially to reduce in the downswing and the hands to arrive readily in front of the ball at impact.

Next normal grip and the thrust applied at the index finger. There is not as above a tendency to reduce the angle in the downswing. But you will likely ‘feel’ more clubhead velocity, a bit more swoosh, through ‘impact’.

Doing the simple experiments above you are really playing and interacting with the mathematical model and proofing for yourself the influence of the magnitude of d. You could equally experiment with the angle of the lead arm / shaft and also with the aiming direction of the trail side thrust.

Yes, correct, it is the thrust which generates the torques. Also true that the acuteness of the lead arm / shaft angle definitely plays a role, as does the distance d between the lead and trail hand ‘connection’ points on the shaft. Have another look at post #1, specifically the parameters and the two formulas for the torques.

 

[rundmc]

rundmc,

We are not dealing with measurements but with a simple mathematical model. This is a very convenient tool and often used in science. One can play with it any desirable way, and substituting reasonable values allows to explore various options.

IMO, the most desirable point of application for the trail side thrust is not the index finger but the heel pad. You want to minimize the parameter d in post #1. Your main goal is to try keep the angle as deep as possible into the down swing.

Do the following experiment. Take a double overlap grip to minimize d as much as possible and do easy 3/4 swings. You should feel a strong tendency for the lead arm / shaft angle initially to reduce in the downswing and the hands to arrive readily in front of the ball at impact.

Next normal grip and the thrust applied at the index finger. There is not as above a tendency to reduce the angle in the downswing. But you will likely ‘feel’ more clubhead velocity, a bit more swoosh, through ‘impact’.

Doing the simple experiments above you are really playing and interacting with the mathematical model and proofing for yourself the influence of the magnitude of d. You could equally experiment with the angle of the lead arm / shaft and also with the aiming direction of the trail side thrust.

Yes, correct, it is the thrust which generates the torques. Also true that the acuteness of the lead arm / shaft angle definitely plays a role, as does the distance d between the lead and trail hand ‘connection’ points on the shaft. Have another look at post #1, specifically the parameters and the two formulas for the torques.

I may have killed too many brain cells to look at those formulas and extrapolate anything. A couple of things . . .

I the thrust and the "angle" a chicken and egg thing? Does the physics of it all imply "try keep the angle as deep as possible into the down swing" the emphasis being on TRY. What does TRY mean in this context? An "muscular effort" or tightness in the wrist?

Also what is "double overlap grip?" Is that just where the last two fingers of the right hand would be on the club?

Muchas . . .

 

[mandrin]

I may have killed too many brain cells to look at those formulas and extrapolate anything. A couple of things . . .

I the thrust and the "angle" a chicken and egg thing? Does the physics of it all imply "try keep the angle as deep as possible into the down swing" the emphasis being on TRY. What does TRY mean in this context? An "muscular effort" or tightness in the wrist?

Also what is "double overlap grip?" Is that just where the last two fingers of the right hand would be on the club?

Muchas . . .

rundmc,

Jim Furyk uses a double overlap grip. Instead of one there are two fingers overlapping the lead hand fingers. It allows the hands to be closer together on the shaft and hence to reduce ‘d’.

It is not a chicken and egg problem but rather a straight cause and effect issue -

Applying trail arm thrust to power the downswing there are two opposing torques at work on the butt end of the handle during the first phase of the downswing. One due to the inertia of the clubhead and one due to the trail arm thrust.

If you reduce ‘d ’ as much as possible, by having the hands as close as possible on the handle, using a double overlap grip, and than further applying thrust with the trail hand heel pad, the torque T1 on the handle is kept to a minimum.

Reducing the torque T1 created by the trail arm thrust allows the inertial torque to be more effective and hence further increase lead hand cocking. There is no ‘muscular effort’ or tightness in the wrists involved to maintain the angle.

 

[rundmc]

rundmc,

Jim Furyk uses a double overlap grip. Instead of one there are two fingers overlapping the lead hand fingers. It allows the hands to be closer together on the shaft and hence to reduce ‘d’.

It is not a chicken and egg problem but rather a straight cause and effect issue -

Applying trail arm thrust to power the downswing there are two opposing torques at work on the butt end of the handle during the first phase of the downswing. One due to the inertia of the clubhead and one due to the trail arm thrust.

If you reduce ‘d ’ as much as possible, by having the hands as close as possible on the handle, using a double overlap grip, and than further applying thrust with the trail hand heel pad, the torque T1 on the handle is kept to a minimum.

Reducing the torque T1 created by the trail arm thrust allows the inertial torque to be more effective and hence further increase lead hand cocking. There is no ‘muscular effort’ or tightness in the wrists involved to maintain the angle.

Very nice . . .