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

[Brian Manzella]

Originally Posted by dbl

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.




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.

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.

[Eyeoffish]

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

[jake2]

Originally Posted by dbl

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.

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]

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.

[jake2]

Originally Posted by ggsjpc

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.

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

[sideyard]

What if the spin loft were negative?

John, Maybe I'm way off here but do you mean if the ball never gets airborn?

Matt

[jake2]

Originally Posted by sideyard

John, Maybe I'm way off here but do you mean if the ball never gets airborn?

Matt

If it's on a tee it will get airborne, just not very far in most situations. Very much a theoretical question from practical golf point of view.

[Brian Manzella]

What is the point of this thread....I am still looking....???

[ggsjpc]

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.