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-   -   Prestressed Shaft and Impact Deceleration (http://www.lynnblakegolf.com/forum/showthread.php?t=2894)

Yoda 05-12-2006 09:23 PM

Grips And Tilt
 
Quote:

Originally Posted by 12 piece bucket

Do y'all think we're seeing Sequenced Release here? Or are these cats playing with a 10-2-D grip?

Zach is definitely 10-2-D. Haven't studied Scott, but...

Check out his extreme 'back' Head position and Axis Tilt here. Look at where his Left Shoulder is in relation to the Ball (not to mention the center of his Stance. There's no doubt he's getting ready to launch one on the Upstroke here!


RickPinewild 05-12-2006 09:24 PM

Offset
 
This may help.
http://www.wishongolf.com/etechrepor...ndex.html#art2

Daryl 05-12-2006 09:30 PM

Quote:

Originally Posted by neil
I see this so much in old books but rarely in Tour Pros video ,is this a deliberate use of an overstiff shaft in order to enhance direction control?,or too soft a shaft to enhance effective loft.Or is it good loading of the shaft PRIOR TO IMPACT to be certain of keeping it loaded through impact ?Is this what actually happens as opposed to what we feel.I would like to see the same swing with the shaft at impact-THE TRUTH!

This is no loading. These are illustrations of exceptional hand eye coordination. They will both loose distance because of clubhead impact deceleration (not that they need anymore). Soft Impact. And, with the shaft bending backward, accuracy too. Just serves to demonstrate how talent can be a compensation.

jmessner 05-12-2006 09:36 PM

Quote:

Originally Posted by EdZ
Food for thought - how would a more flexible shaft with more offset (hook face) alter the way we see this forward bending?

How much does axis tilt play into the equation, if at all?

As long as thrust (lag pressure) is maintained and Rhythm and aiming point is correct, I see no reason that there should be forward shaft bend until AFTER seperation - indeed, ideally after both arms straight if at all.

The fact that so many people have this forward bend demonstrates how rare proper aiming point and Rhythm are - that people are not paying attention to 1-L-15, and that over acceleration happens with even the best of players.

Folks - I swear I am not trying to shake your faith with this forward bending thing, but it is an artifact of the physics. I personally don't see how it materially changes the model that TGM proposes.

Just for the sake of completeness, I will add some references here because people may think I'm making this up.

1) Cochran & Stobbs, "The search for the perfect swing", 1968.
See Figure 32:5 Caption "How bending the shaft forward, as it always is just before impact, closes the face of the club....."

2)Jorgensen, "The Physics of Golf", 1994
See Fig 12.1, also last paragraph of Chapter 12 - "...I think the flexing of the shaft forward as the clubhead comes into the ball is a general characteristic of the golf swing. Photographs made with the use of a focal plane shutter must be ignored in this context. There are few photographs in golf literature made with stroboscopic light sources, but of those I've examined, all of them show clubs flexed in this manner."

3) Horwood (Technical Director Apollo Golf Shafts), "Flexes, Bend Points and Torques", Golf The Scientific Way, 1995 pg 103-108
See Figure 1 "Shaft Bending in Typical Swing" and accompanying text- "Although over half of the 2 second time interval covered by the trace in Figure 1 is taken up by the back swing, it can be seen that the shaft goes from being bent backwards (by about 3 inches) to being bent forwards (by about 2 1/2 inches) in the instant before impact with the ball."

4) Butler & Winfield (True Temper Sports), "What Shaft is Best for You?", Golf The Scientific Way, 1995 pg 113-115
See Figure 1 for deflection curves of a shaft. Accompanying text- "During the load up time, the shaft first loads or deflects anywhere from 2 to 7 inches for a driver. The shaft then unloads and kicks forward at impact."

5) Wishon, "The Search for the Perfect Golf Club", 2005
See Chapter 4 under Three Myths-
"Myth number Two-The second myth is that the clubhead sometimes(usually? often? always?) will "lag behind" just before impact with the ball. .....The release of the wrist-cock also applies something called centrifugal force to the club. That centrifugal force combined with the arms slowing down and the club speeding up causes the shaft to begin to bend forward. And because the arms DO slow down when the wrist-cock is released, the shaft HAS to bend forward before hitting the ball."

Daryl 05-12-2006 09:36 PM

Quote:

Originally Posted by Yoda
Zach is definitely 10-2-D. Haven't studied Scott, but...

Check out his extreme 'back' Head position and Axis Tilt here. Look at where his Left Shoulder is in relation to the Ball (not to mention the center of his Stance. There's no doubt he's getting ready to launch one on the Upstroke here!


Yes I see it too, now that you've pointed it out. Thanks, it's clearer now. Wow, I wonder if trying to launch on the upstroke has lead to the body alignments?

birdie_man 05-12-2006 09:40 PM

He prolly setup with his head back...I'd guess.

neil 05-12-2006 09:42 PM

Quote:

Originally Posted by neil
I see this so much in old books but rarely in Tour Pros video ,is this a deliberate use of an overstiff shaft in order to enhance direction control?,or too soft a shaft to enhance effective loft.Or is it good loading of the shaft PRIOR TO IMPACT to be certain of keeping it loaded through impact ?Is this what actually happens as opposed to what we feel.I would like to see the same swing with the shaft at impact-THE TRUTH!

I repeat.......

Daryl 05-12-2006 09:54 PM

Quote:

Originally Posted by jmessner
Folks - I swear I am not trying to shake your faith with this forward bending thing, but it is an artifact of the physics. I personally don't see how it materially changes the model that TGM proposes.

Just for the sake of completeness, I will add some references here because people may think I'm making this up.

1) Cochran & Stobbs, "The search for the perfect swing", 1968.
See Figure 32:5 Caption "How bending the shaft forward, as it always is just before impact, closes the face of the club....."

2)Jorgensen, "The Physics of Golf", 1994
See Fig 12.1, also last paragraph of Chapter 12 - "...I think the flexing of the shaft forward as the clubhead comes into the ball is a general characteristic of the golf swing. Photographs made with the use of a focal plane shutter must be ignored in this context. There are few photographs in golf literature made with stroboscopic light sources, but of those I've examined, all of them show clubs flexed in this manner."

3) Horwood (Technical Director Apollo Golf Shafts), "Flexes, Bend Points and Torques", Golf The Scientific Way, 1995 pg 103-108
See Figure 1 "Shaft Bending in Typical Swing" and accompanying text- "Although over half of the 2 second time interval covered by the trace in Figure 1 is taken up by the back swing, it can be seen that the shaft goes from being bent backwards (by about 3 inches) to being bent forwards (by about 2 1/2 inches) in the instant before impact with the ball."

4) Butler & Winfield (True Temper Sports), "What Shaft is Best for You?", Golf The Scientific Way, 1995 pg 113-115
See Figure 1 for deflection curves of a shaft. Accompanying text- "During the load up time, the shaft first loads or deflects anywhere from 2 to 7 inches for a driver. The shaft then unloads and kicks forward at impact."

5) Wishon, "The Search for the Perfect Golf Club", 2005
See Chapter 4 under Three Myths-
"Myth number Two-The second myth is that the clubhead sometimes(usually? often? always?) will "lag behind" just before impact with the ball. .....The release of the wrist-cock also applies something called centrifugal force to the club. That centrifugal force combined with the arms slowing down and the club speeding up causes the shaft to begin to bend forward. And because the arms DO slow down when the wrist-cock is released, the shaft HAS to bend forward before hitting the ball."

Excellent post. I can appreciate the amount of work you have researched. However these authors are merely stating observation, not science. They fail to explain why, or state anything other than conjecture.

There is one more Author to consider.

See 6-C-0 #2. There is a reason for that parachute.
6-C-2-A. If the Pressure Point pressure that produced the initial Clubshaft flex is maintained it will maintain the flex also.

jmessner 05-12-2006 10:06 PM

Quote:

Originally Posted by Daryl
Excellent post. I can appreciate the amount of work you have researched. However these authors are merely stating observation, not science. They fail to explain why, or state anything other than conjecture.

There is one more Author to consider.

See 6-C-0 #2. There is a reason for that parachute.
6-C-2-A. If the Pressure Point pressure that produced the initial Clubshaft flex is maintained it will maintain the flex also.

The authors I mentioned used high speed video, stroboscopic photographs, and strain gauge measurements to support their reasoning. I'm not sure that HK had those available to him, and, if not, made a perfectly reasonable assumption based on the facts he had at the time. If he did, I'm sure many would be interested in that data.

Daryl 05-12-2006 10:17 PM

Quote:

Originally Posted by jmessner
The authors I mentioned used high speed video, stroboscopic photographs, and strain gauge measurements to support their reasoning. I'm not sure that HK had those available to him, and, if not, made a perfectly reasonable assumption based on the facts he had at the time. If he did, I'm sure many would be interested in that data.

I'm sure that all of the tools used in "Search for the perfect swing" were available to Homer.

The authors you quote explain their observations. I don't disagree with what they observed. However they fail to explain what causes the shaft to bend backwards. Additionally, they don't conclude what effect this has on impact. Third, they don't advocate this procedure. They have only observed it. In other words, they imply much, prove nothing. Please do me the favor of observing one more photo. Visit the section on this site named "Champions at Impact" and review Lee Trevino at impact. Then, in your own words, if you would kindly do so, explain your observations to me.


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