Extending flat spot

[drewitgolf]

Good question. I hope that Michael or Brian chimes in on this, but my understanding from the release thread was that the simple model of force directed (almost) entirely along the line of the shaft was being superseded. From the video, I understand the part of the downswing from left arm horizontal to handpath lowpoint to be the part of the downswing where force can most effectively be applied across the shaft.

I don't believe Dr. Williams wants any force accross the shaft or he believes it is not necessary.
Scientists often disagree. I guess if they all agreed all the time there would not be a need for so many of them.
In Corchran and Stobbs book the Search for the Perfect Swing, the two golfer's with the "near perfect swings" to the double pendulum model were actually one armed golfers (no right arm). Both had single digit handicaps (no pun intended), reference Search for the Perfect Swing 5:1. Maybe it all depends upon your frame of reference. So many questions.

 

[TeeAce]

Thanks, I understand a little more what your diagram and graph were measuring. I agree that there is a difficultly in measuring accurately the comparisons of hand paths. It seems to me that the best way would be to measure the actual distance traveled by the hands by having multiple sensors/cameras set up in multiple locations surrounding (around as well as above and as many angles in between as possible) the player to have the best accuracy in measuring the 3 dimensional hand movement. So then you could show the backswing hand path being say 20cm back+40cm up&back+90cm up&back&behind= 150cm long compared to how long the components of the downsiwng hand path is.

The hand path distances measured could then be compared to any "hub" movement measured in any direction. In this way there would be a more definitive quantifiable 3d measurement with relation to hand path in backswing compared to the downswing coupled with any body or hub movement. It has probably already been done, maybe by the scientists Brian is working with, I just am not aware of it.

Thats what we do. We know the 3D location of 27 different points all the time and after that its only calculation.

The problem is bad definitions. Wider arc at "downswing" can be true or false and depended of the moment of observation. Where is the hub and how to measure that relation? Is it neck, left shoulder or somewhere between those? Maybe somewhere under that line but where?

But still the left arm length puts some limits for that. It doesn't get longer if it's straight so only way to get it away from the hub is to move it sideways and away from the chest.

I believe all good players got wider arc relative to the hub at impact than they got at setup. The other parts of the statements can not be busted or confirmed with this information

 

[Michael Jacobs]

Thanks for the thoughtful reply Michael.
If I could follow up…Do you or the scientist that you consult with believe that Dr. Williams' calculations that the smallness of the drag at right angles to the shaft throughout the entire downswing is negligibly small is correct, never more than one pound? In other words, the only substantial force acting on the club is along the shaft lengthwise, which peaks at 70lbs?

Depends on the subject being tested... Players naturally will have different amounts but there will be many similarities in the well timed players. David Williams performed the calculations of the Spalding pictures of Bobby Jones

We have handy a lot of data from many subjects .. I believe I posted some statistics in the release thread

 

[SteveT]

mandrin et al:

Interesting descriptive geometry construct, but let's relate it to a real-life golfswing.

If we assume the big black dot in your diagram is the centre of rotation, it should drop by an inch or so in the downswing and then rise back up to an impact position with the straightening of the lead leg and the changes in the length and orientation of the spinal column... creating another dimensional factor. Agreed?

Then there is the final pronation of the lead forearm/hand to square the clubface to impact. The pronation can be somewhat gradual for the longer length driver and quicker for the wedges. The hands coupling point distance between the rear hip low point and elevated impact point is when pronation, squaring and parametric elevation must be finally completed.

What this all leads to in reality, is that the 'flat spot' need only occur is say the last 2 inches into impact when there is a square clubface and pronation completed in the downswing.

Using circle geometry, that last 2 inches on a say 60 inch swing radius would only be a final rotative sweep of say 2 degrees. Without doing the trigonometry, I intuitively believe that the final 2 inches can be considered "flat" or tangentially straight on such a large radius circle. Agreed?

Suggesting that the flat spot can be as long as 18 inches per Moe Norman is questionable. Moe had a 'windmilling' swing with extremely extended arms, when I saw him twice in live demoes in the 1980s (and he was calling out his 200 yard drives as "300 yards"!).

If your geometrical figure had the arm-club segment fully straightened out for impact, then the clubhead would be rising after the shoulder span is rotating above level.

The question is: Do pro golfers optimally reach impact when their lead shoulder is slightly above level, or do they reach impact when their shoulders are level ... and everything happens so fast that it's impossible to eyeball it even on a youtube video? Kinetically I think it would be when the shoulders are level.

Perhaps the answer lies with the Manzella scientific team and their elegant testing equipment and procedures for a kinematic/kinetic solution.

Another consideration is that arc differences on a large radius circle or ellipse/oval as in a golfswing should be considered as a straight line for small incremental segments such as the ~3/4 inch of the impact event (3/8 inch of compression and 3/8 inch of rebound).... and the only difference is whether the "line of compression" is down, level or up. There is no circular scooping as suggested in TGM... and that thought should not enter into the minds of proto-scientific thinking golfers on this fine forum!

Your thoughts .....

 

[birly-shirly]

Good lord. SteveT? Have you been serving a custodial sentence? People were worried about you...

 

[SteveT]

Good lord. SteveT? Have you been serving a custodial sentence? People were worried about you...

I had a sex change operation that went wrong and I gave up on golf... Now I'm only a scientific golfing expert.

What do you think about my 'flat spot' observations ... let's get down to business here.

 

[birly-shirly]

That at least proves it's really you - and not some imposter stolen your log-in!

I've wondered about your point in your last paragraph. You might be right to treat a 3/4inch segment of an arc as essentially a straight line - I don't have the maths to say one way or t'other. However, I think you might need to look at a longer segment. Not because impact lasts longer, but because of human error and timing issues. I'm starting to think that the great value of the flat spot on the arc is that you have a controlled angle of attack for a long enough stretch that you have a decent chance of catching the ball during that interval.

Previously, I've found it much easier to make solid contact with anything from an 8 to a 4 iron, than with a wedge. I have no empirical proof of this, but my guess is that with a partial wedge swing, my angle of attack was varying so rapidly within, say, 6 inches either side of the ball that it was really difficult, or lucky, to make contact just at the instant when the clubhead was moving slightly downward.

 

[SteveT]

@ birly-shirly .... yes it's me, and you make an interesting point about your 4 - 8 irons and wedges and your solid contact feel.

What you may be feeling is the feedback from well squashed ball on a lower lofted clubface, while with the wedges the ball is somewhat 'glanced' by the higher lofts. I play with 4 wedges and have the same lack of orgasmic impact feel mainly because I nip the ball rather than drive the wedges into the ground, like I do with the other short irons. That's just my golfswing solution because I'm tall and have a steep swing plane.

You say: "...the great value of the flat spot on the arc is that you have a controlled angle of attack for a long enough stretch that you have a decent chance of catching the ball during that interval."

Brian did say on his "Things we now know for sure" topic thread:

3. You HAVE NO CHANCE—none—telling the attack angle of a golf swing without a radar device like TrackMan.

Notwithstanding that, I agree with you particularly with the driver swing where I tee it up with a 3" tee and somewhere between my left heel and toe, depending on how my swing forms up that day. Ball position and club selection will dictate where your flat spot exists.

As for the ball in the 3/4 inch impact event, it doesn't recognize any circle arcing... only down, level or up resultant forces.

What do you think about the final release action of pronation completion coming into the ball? Do you have a gradual pronation or a snap pronation, and for which clubs? I think that might explain a lot.

 

[birly-shirly]

@ birly-shirly .... yes it's me, and you make an interesting point about your 4 - 8 irons and wedges and your solid contact feel.

What you may be feeling is the feedback from well squashed ball on a lower lofted clubface, while with the wedges the ball is somewhat 'glanced' by the higher lofts. I play with 4 wedges and have the same lack of orgasmic impact feel mainly because I nip the ball rather than drive the wedges into the ground, like I do with the other short irons. That's just my golfswing solution because I'm tall and have a steep swing plane.

No. I'm not talking about small differences between decent quality impacts. I'm talking about drop-kicks and thins.

You say: "...the great value of the flat spot on the arc is that you have a controlled angle of attack for a long enough stretch that you have a decent chance of catching the ball during that interval."

Brian did say on his "Things we now know for sure" topic thread:

3. You HAVE NO CHANCE—none—telling the attack angle of a golf swing without a radar device like TrackMan.

Yes - but I think Brian is talking about being able to tell AoA reasonably precisely, ie measurable in degrees. I don't think you need a trackman to discriminate between steeply downward, shallow downward and level or upwards through impact. Admittedly it gets grey at the boundaries - but I think you can pick up and identify gross errors.

Notwithstanding that, I agree with you particularly with the driver swing where I tee it up with a 3" tee and somewhere between my left heel and toe, depending on how my swing forms up that day. Ball position and club selection will dictate where your flat spot exists.

Agreed - but if you can extend the flat spot you have a greater chance of launching the ball well, no?

As for the ball in the 3/4 inch impact even, it doesn't recognize any circle arcing... only down, level or up resultant forces.

I dont' know. But I asked Mandrin and he replied at post 43 above.

What do you think about the final release action of pronation completion coming into the ball? Do you have a gradual pronation or a snap pronation, and for which clubs? I think that might explain a lot.

Again - don't know. Not sure I would know how to go about classifying myself.