Just for Fun. A theory.......

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ggsjpc

ggsjpc

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I have my own theory, but could someone give me theirs about why there doesn't seem to any consensus on the percentage of start direction relative to the face? I've seen as low as 60% and high as 85% even though, in terms of direction, a straight shot starts exactly where the face is pointed(directionally).

BTW-I'll be happy to share my theory also.....
 
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mjstrong

mjstrong

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Clubhead speed must be a factor.

Imagine a very short putt, I would think that would tend towards the higher percentage. A higher-friction impact (deep grooves, etc.) might let the path influence more.
 
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dbl

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ggsjpc said:
I have my own theory, but could someone give me theirs about why there doesn't seem to any consensus on the percentage of start direction relative to the face? I've seen as low as 60% and high as 85% even though, in terms of direction, a straight shot starts exactly where the face is pointed(directionally).
Click to expand...

Why do you seek a consensus? The earth being flat was popular too once, but not correct.

Anyway, as I recall there was a study on the influence that the face direction has, and the 85% figure was for short irons, while up at the driver, there was less influence by the face's direction. Was it 70%? I don't recall precisely. But if you are planning some grand theory, it shall have to have a variable for the face's influence depending on loft, club design, length etc.
 
ggsjpc

ggsjpc

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dbl said:
Why do you seek a consensus? The earth being flat was popular too once, but not correct.

Anyway, as I recall there was a study on the influence that the face direction has, and the 85% figure was for short irons, while up at the driver, there was less influence by the face's direction. Was it 70%? I don't recall precisely. But if you are planning some grand theory, it shall have to have a variable for the face's influence depending on loft, club design, length etc.
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You're right.

No consensus needed.

Thank You.

Brian or any moderator feel free to delete this thread. Thanks.

John
 
B

Brian Manzella

Administrator
ggsjpc said:
You're right.

No consensus needed.

Thank You.

Brian or any moderator feel free to delete this thread. Thanks.

John
Click to expand...

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dbl

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Hey ggsjpc, my answer was more on dplane for path versus face when there is a horizontal divergence. Brian's answer was on the ball's reaction to the face's loft on straight shots.

Maybe give your thoughts and we can see the situation you're concerned with.
 
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ggsjpc

ggsjpc

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My word is my bond.......

Brian, thanks for the reply. I agree with your examples but as dbl referenced, I was questioning situations when the face, the starting height, and 3d club path direction don't line up(like they do for a straight shot).

As you mentioned in your video, friction certainly places the starting height closer to the path angle so that would be one reason why when they don't line up their would be variance in 2d starting direction relative to face and 2d path.

I also think that angle of attack also plays a role in the perception of starting direction. If I assumed the same friction and dynamic loft, the lower the spin loft (Angle of attack relative to dynamic loft) when the d plane is tilted it would appear that the starting direction is closer to the path.

Just my theory.
 
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dbl

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The dplane is constructed by a geometric ray which is normal to the clubface and by a ray which is along the path. For a straight shot, the dplane is entirely vertical. For simplification about friction and so forth that Brian was mentioning, say the ray normal to the clubface is just some degrees like 44 degrees vertical for an iron and for the second example 20 degrees for a wood.

Theory:
The situation is that for low loft (or take off angle) the path deforms the dplane more from vertical. And note, the ball has to take off initially on the dplane.

I've taken two photos using drum sticks for the two geometric rays. For the plane, think about a peice of paper draped over the two sticks.

Consider for example a fade shot with 5 degrees of out to in path.

Photo1 is the "wood shot" with say 20 degrees of initial vertical direction. The dplane is tilted to the right severely at least compared to the second photo.

<img src="http://img638.imageshack.us/img638/4374/img335820.jpg">



Photo2 is the "iron shot" with say 44 degrees of initial direction but same 5 degrees of out to in path. The dplane is barely tilted compared to a straight shot.

<img src="http://img638.imageshack.us/img638/4290/img335920.jpg">


The math for the degrees of these "3d" triangles could be calculated but for now I'm not going to take the time, and my high school kid is busy. :)
 
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B

Brian Manzella

Administrator
dbl said:
The dplane is constructed by a geometric ray which is normal to the clubface and by a ray which is along the path. For a straight shot, the dplane is entirely vertical. For simplification about friction and so forth that Brian was mentioning, say the ray normal to the clubface is just some degrees like 44 degrees vertical for an iron and for the second example 20 degrees for a wood.

Theory:
The situation is that for low loft (or take off angle) the path deforms the dplane more from vertical. And note, the ball has to take off initially on the dplane.

I've taken two photos using drum sticks for the two geometric rays. For the plane, think about a peice of paper draped over the two sticks.

Consider for example a fade shot with 5 degrees of out to in path.

Photo1 is the "wood shot" with say 20 degrees of initial vertical direction. The dplane is tilted to the right severely at least compared to the second photo.

<img src="http://img638.imageshack.us/img638/4374/img335820.jpg">



Photo2 is the "iron shot" with say 44 degrees of initial direction but same 5 degrees of out to in path. The dplane is barely tilted compared to a straight shot.

<img src="http://img638.imageshack.us/img638/4290/img335920.jpg">


The math for the degrees of these "3d" triangles could be calculated but for now I'm not going to take the time, and my high school kid is busy. :)
Click to expand...

Nice post, DBL.

You may find this strange, but a I did a 2 hour mutli-media explanation at the GTE.

John Graham was there.
 
ZAP

ZAP

New
I do not think you can even come up with an exact number. More like a range for lofts?
Maybe?
 
J

jake2

New
D-plane and initial ball flight direction

dbl said:
The dplane is constructed by a geometric ray which is normal to the clubface and by a ray which is along the path. For a straight shot, the dplane is entirely vertical. For simplification about friction and so forth that Brian was mentioning, say the ray normal to the clubface is just some degrees like 44 degrees vertical for an iron and for the second example 20 degrees for a wood.

Theory:
The situation is that for low loft (or take off angle) the path deforms the dplane more from vertical. And note, the ball has to take off initially on the dplane.

I've taken two photos using drum sticks for the two geometric rays. For the plane, think about a peice of paper draped over the two sticks.

Consider for example a fade shot with 5 degrees of out to in path.

Photo1 is the "wood shot" with say 20 degrees of initial vertical direction. The dplane is tilted to the right severely at least compared to the second photo.


Photo2 is the "iron shot" with say 44 degrees of initial direction but same 5 degrees of out to in path. The dplane is barely tilted compared to a straight shot.
Click to expand...

Nice way of illustrating d-plane. I think this has got a lot to do with ball flight curvature. Maybe less with what percentage of initial direction comes from the face vs. path.

My thinking is that the more d-plane tilts, more the ball is going to curve and this is due to to ball spin axis tilting. More tilt, more curvature. I'm assuming that balls initial spin axis is perpendicular to d-plane, but that I've not confirmed that from anywhere. If you like representation of side-spin and backspin numbers separately, the you could say that bigger the ratio between side-spin / backspin, the more spin axis is tilted and the more the ball is going to curve.

My understanding of the d-plane theory is that the relationship between face and true path is the same in the vertical and horizontal planes. Ball launches lower than the dynamic loft and inside of where the face points, i.e. both x % towards the true path.

I think, besides friction, ball deformation during impact is a big factor on the initial direction, where exactly it is between the face and true path. This would be one explanation why it can differ from club to club. It could then differ from one type of ball to another too.
My simple theory is that when the ball is deformed, it is not going to slide up the face and it's going to resist rolling up the face too. This means that there is a time during impact that the ball is (almost) moving with the head and gains in a way a an extra velocity component towards the path during this time.

The impact physics are very complex, of course, and this is just my way of trying to think things in simple terms.
 
ggsjpc

ggsjpc

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Does everyone think the ball always starts between the face normal and 'true' path?

What if the spin loft were negative?

Would it still start between the two?

Again, nothing you would want to do. Just theory for fun.
 
J

jake2

New
ggsjpc said:
Does everyone think the ball always starts between the face normal and 'true' path?

What if the spin loft were negative?

Would it still start between the two?

Again, nothing you would want to do. Just theory for fun.
Click to expand...

I don't see why negative spin loft would make a difference.
 
ggsjpc

ggsjpc

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Brian,

Like I said at the beginning, it's just for fun to think out of the box. As I mentioned before, feel free to take it down at anytime.
 
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