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Maximum Compression
Looking for clarification on Sustaining the Line of Compression. Assuming that the sweet spot is moving on an inclined plane during the impact interval, and the cluface is square to that plane at separation, what factors will provide maximum compression or compression leakage? Assume contact on sweet spot at impact and same clubhead speed at separation.
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Nice question. I've got a few factors for your consideration:
1. The loft of the club. Added loft itself will "leak". Intentional by design compression leakage. Although some backspin is necessary for flight. But we're talking theoretically I think. So theoretically shouldnt the direction the face points three dimensionally and the line of compression be one and the same for total compression.........which could imply negative loft in some instances? 2. Hinge Action. Horizontal is "closing only, no layback". Vertical is "layback only no closing". Angled is a bit of both depending upon the plane angle. As the angle approaches perfectly Vertical, Angled Hinging approaches the characteristics of Vertical Hinging (layback only no closing). Vice versa for the situation where the plane angle approaches Horizontal.....Angled Hinging approaches the characteristics of Horizontal Hinging (closing only with no layback). Which should probably make for a third factor ... 3. The Plane Angle. 4. How bout the Angle of Attack? That would cause the Line of Compression to be divergent from the target line wouldnt it? 5. Ball position vis a vis low point? I dunno but my head hurts already. What does trackman say, Max? I hopped on a Flightscope the other day. Interesting but not enough info on that particular unit maybe. Either that or I didnt know where to look. The thing that really jumped out at me was how constant my swing speed was for different amounts of effort.......made me start swinging slower and better right away. My apologies for the digression. |
2-D-0
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Thanks to OB and the others for responses. In the TrackMan world, the "equivalent" to a measurement of ball "compression" is what is known as "Smash Factor", which is initial ball speed divided by clubhead speed at impact. The lower the loft, the greater the potential for this number to be. So a driver can be as high as 1.5, and short irons dip below 1.4 as a "best case scenario". The Dynamic Loft is the vertical angle of the "normal" to the clubface, relative to the ground, during impact. But it is this loft relative to the vertical Attack Angle which is the loft that the ball "feels". This is known as the Spinloft. Regarding Homer's Clubface Lay-Back...if the clubface does lay or tilt backwards from impact to separation, relative to the clubhead arc, increasing the Spinloft, then, all else the same, the compression will be less than if the Spinloft had remained the same during the interval. This seems pretty straightforward, if I am interpreting Clubface Lay-Back correctly.
But 2-C-1, Swingers Hinging says, in essence, that for maximum compression, the clubface must rotate around the same center as the shaft during the interval. I am looking for clarification of this. |
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For theoretical total compression the point of contact between ball and face must remain connected ( Homer said "as if welded together") during the impact interval. No "wobble" so to speak. But for lofted clubs the ball will roll on the face to varying degrees as you mention. Which Homer assumes to be the case in 2-C-1. Wobble or leakage due to loft. That slightly glancing blow due to loft aside to maintain the point of contact between ball and face throughout the interval requires a uniform motion or arc. Meaning that the angled clubshaft and the closing clubface are both rotating around the same center. At the same rate. Horizontal Hinging , closing only with no layback does not add loft dynamically during the impact interval , which would deaden the blow , compression leakage. Something that can be used intentionally to great effect on short shots but is the hackers floating tee ball shot. Normally the result of "Steering" the clubface square to the hole in a misguided attempt to add a linear, inline , square to square blow to a ball that should be hit with an arcing clubhead and a closing face. I must admit to not being able to draw the clubfaces center for vertical hinging. I go all foggy on that bit of business. Homer did these drawings however.......I wish they'd made the book. Words do fail when describing geometry. Angled Hinging it is said , has no center for the clubfaces motion...... Maybe Lynn could explain or draw it out some day. |
Thanks, OB. Yeah, I guess that's the essence of my question....why would a clubface that is open to the clubhead arc at impact and square at separation (horizontal hinging) allow the original contact points to remain intact through the interval but a clubface square to the clubhead arc at both impact and separation (angles hinging) would not?
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For additional clarification, there is another way to look at Hinge Action compared to the "Normal to the Path" rotation of the Clubface. In "Normal to the Path" rotation, the Clubface stays aligned to the Clubhead Orbit. This causes a corresponding Clubshaft Rotation around the Longitudinal Center of Gravity of the Golfclub. Hinging changes that. For Horizontal Hinging, the Longitudinal COG and Shaft, at Impact, are vertical, one above the other, due to the Mandatory Flat Left Wrist. They Both Rotate, together around the Hinge Pin but maintain their Vertical relationship to the Horizontal Plane (the associated Plane). This is very different than the Shaft continuing to rotate around the COG of the Golfclub as it would in a "Normal to the Face/Path" which is "Swiveling through Impact". In Angled Hinging, we have the same geometry except that the Hinge Pin is angled and the Longitudinal Center of Gravity of the Golfclub and Shaft maintain their relationship to the Angled Plane (Associated Angled Plane). Trackman identifies "Spin Loft". This is probably very good to identify whenever you don't use Hinging. When not using Hinging, the Ball will roll on the clubface. TGM has such cases, for example, the Lob Shot, etc. For anyone using Hinging, Clubface Loft is considered at separation. TGM states that Vertical Line of Flight is a resultant force, and is a line bisecting the Line of Compression and the Rebound Direction. The Rebound Direction is 90 degrees to the line of compression (Angle of Approach, Angle of Attack). When striking a golf ball, if you lose the line of compression before separation, then you introduce scattered force vectors and it will result in scattered rebound vectors which will result in scattered resultant Force Vectors. That would be a Mis-Hit, poor execution unless done intentionally, and that will change the Vertical Line of Flight, Loft. TGM considers "Smash Factor". It is not the quality of compression but how much of the ball was compressed. See Below: Also note that each line receives maximum compression.  When considering Layback, the Clubface is Laying Back relative to the Hinge. This is different than the "Normal to the Path" clubface layback that Trackman calculates because the Clubface is also closing about the Hinge Pin. In Angled Hinging, Layback does not necessarily lose compression because the Impact and separation points remain the same, but it will compress less of the ball by about 1/10,000 of an inch. Rather, Layback tilts the balls spin Axis. |
Pennsylvania Six Five O. O. O.
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Know what you mean, its a head scratcher when you think of it in those terms. The compensation for the slice tendency of Angled Hinging is a slightly closed clubface at Address, so no doubt its got to do with a "divergence" between face and path. Like the ball wants to be "cradled" so its doesnt roll off the face. Im an old hockey player so it seems like that to me.......another game with a similar implement. Ive always wanted to hit one of those curved face golf clubs from yesteryear. Curved hockey sticks were the cats pajamas when they first came out. What once was a muffin turned into a rocket. |
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I'm very comfortable with my understanding of how the impact collision between ball and clubface create Initial Launch Conditions and the resulting ball flight, which comes not only from TrackMan, but from the many scientists who have researched this. I doubt that the book can add anything to the knowledge of the distinguished scientists who are the present-day experts in this field. I am simply just trying to understand what Kelley meant when he wrote the things he did. Here's some measurable conditions of the impact collision which nobody is exempted from and some traditional golf instruction terms to describe them.....During the collision, the clubhead is moving. The direction of this movement at separation has a vertical direction, relative to the ground, called the Angle of Attack, and a horizontal direction along the ground, relative to the Target Line, called Clubhead Path. The "normal" (dictionary term) to the clubface at separation also has a vertical direction, relative to the Attack Angle, called Spinloft, and a horizontal direction, relative to the Target Line, called Clubface Angle. This is the language that I speak. Is is possible that someone could describe, in my "native" tongue, what Kelley is describing in 2-C-1? |
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