The Old Ball Flight Laws

[Todd Dugan]

Isn't the biggest factor in creating spin, in Spin Loft, or the difference between dynamic loft and angle of attack?

So, if you hit more down on the ball, but maintain the same loft, you will create more spin.

Spin Loft is the greatest factor contributing to spin rate, along with clubhead speed. But as you hit down more on the ball, dynamic loft is reduced as well. So using the formula, "dynamic loft - attack angle = spin loft", the net result ends up the same.

 

[Brian Manzella]

Spin Loft is the greatest factor contributing to spin rate, along with clubhead speed. But as you hit down more on the ball, dynamic loft is reduced as well. So using the formula, "dynamic loft - attack angle = spin loft", the net result ends up the same.

No

 

[westy]

ball flight

A drunk old scotsman discovered ball flight on the way home from the pub with his walking stick. (Cheers...)
Theories on how it worked then ensued. (I dont care who was closest...)
Now a little orange box can measure it, and the evidence is fundamentally useful. (that matters because we can now assume complete control theoretically)
Lets get on with developing this evidence, because as far as I can tell, this is the best open source forum for R&D in existence. Someone please let me know if there is a better one....
Fact of life. People want to sell stuff so they package it. what i like about here is that correct is what matters.

 

[westy]

spin

Is shearing force. Anything else?
Shearing force is the two vectors pointing different places, the further apart, the more shear.
Friction (grip) between the two contacting surfaces is important also.

 

[Steve Khatib]

Steve,
Somehow you missed Todd's essential approach to all of his posts- it wasn't "you're all crazy". In fact, it leaned much more for an appreciation of this forum and a respect for it.

Maybee I and others did also. It is simple though find the information that is availible to back up youre statements, otherwise its a waste of everyones time. Happy to hear all ideas that can be substanciated in some way.

 

[westy]

Clubhead path and clubface angle are chief determiners of ball flight. So they are extremely relevant. Honestly, I don't introduce the term "D-plane" with my students. But I spend time making sure that they understand how clubhead path and clubface angle influence the ball's flight.

Why not?
Seems to me this is an important question.
Spending time on face and path influence IS D-plane....
Do you explain that if you hit down at a ball you need to aim left? (up = right)

 

[Kevin Shields]

Spin Loft is the greatest factor contributing to spin rate, along with clubhead speed. But as you hit down more on the ball, dynamic loft is reduced as well. So using the formula, "dynamic loft - attack angle = spin loft", the net result ends up the same.

Dynamic loft + A^A = spin loft if you hit down

 

[Todd Dugan]

Why not?
Seems to me this is an important question.
Spending time on face and path influence IS D-plane....
Do you explain that if you hit down at a ball you need to aim left? (up = right)

Aim or body alignment does not guarantee a particular horizonatal swing plane or path. So you don't NEED to aim left if you hit down. However, I CAN certainly explain why the horizontal plane line would need to be out-to-in of the target line for a true straight shot with a descending attack angle. Along with a nice visual demonstration on an inclined plane model.

I let folks know the importance of center contact on the clubface. But without explaining "coefficient of restitution". One can understand how clubhead path and clubface angle effect ball flight WITHOUT knowing that connecting these two vectors creates something know as the "D-Plane". Believe me, if I thought that throwing that term out there would help my students to better understand the impact collision conditions which govern ball flight, I would.

 

[Todd Dugan]

Dynamic loft + A^A = spin loft if you hit down

The TrackMan definition of spin loft is: the difference in angle between dynamic loft and attack angle. Another way to express this is to say: Dynamic Loft MINUS attack angle EQUALS spin loft. I'm under the impression that a scientific formula is absolute.

Either way, the main point is that Fredrick Tuxen has presented that so long as impact location on the clubface, clubhead path, clubface angle, and clubhead speed remain the same, then an increase to the negative attack angle will not produce an increase in backspin. Is this in contention by you, Kevin? Or Brian?

 

[Brian Manzella]

Aim or body alignment does not guarantee a particular horizonatal swing plane or path.

I think we have said this a couple of dozen times.

NOTHING guarantees a swing direction OR a resultant path.

I CAN certainly explain why the horizontal plane line would need to be out-to-in of the target line for a true straight shot with a descending attack angle. Along with a nice visual demonstration on a inclined plane model.

No need to audition on here, we have done so many D-Plane demos and explanations, including the one at the GTE where I RAN with the ball on the D-Plane.

Really.

One can understand how clubhead path and clubface angle effect ball flight WITHOUT knowing that connecting these two vectors creates something know as the "D-Plane".

No it won't.

But, most players don't NEED to know.

Or want to.

Believe me, if I thought that throwing that term out there would help my students to betterunderstand the impact collision conditions which govern ball flight, I would.

I do when I think it will help.

25%-33% of the time.

 

[Brian Manzella]

Ah...m=no

But as you hit down more on the ball, dynamic loft is reduced as well.

No.

I repeat.

N—O.

You can hit down more and deliver MORE LOFT or hit up and deliver LESS.

You got it?

 

[Todd Dugan]

No.

I repeat.

N—O.

You can hit down more and deliver MORE LOFT or hit up and deliver LESS.

You got it?

Sure, it's possible. But when the shaft becomes vertical to the plane it SHOULD be at low point. So shaft lean at impact SHOULD INDICATE attack angle. Two conditions that would disrupt that are the swing center raising or lowering or the radius from the left arm to the clubhead lengthening or shortening, during impact (let's not consider shaft bend, for the moment). Assumimg those things are not happening, and they shouldn't be, then you deliver the same spin loft, regardless of attack angle. That's why Fredrick is saying that changing ONLY your attack angle will not change spin rate. But it DOES change your dynamic loft, and thus the launch angle.

 

[mjstrong]

Sure, it's possible. But when the shaft becomes vertical to the plane it SHOULD be at low point. So shaft lean at impact SHOULD INDICATE attack angle. Two conditions that would disrupt that are the swing center raising or lowering or the radius from the left arm to the clubhead lengthening or shortening, during impact (let's not consider shaft bend, for the moment). Assumimg those things are not happening, and they shouldn't be, then you deliver the same spin loft, regardless of attack angle. That's why Fredrick is saying that changing ONLY your attack angle will not change spin rate. But it DOES change your dynamic loft, and thus the launch angle.

Todd, wouldn't axis tilt be a very common condition that causes low point to differ from when shaft lean would predict?

 

[Kevin Shields]

The TrackMan definition of spin loft is: the difference in angle between dynamic loft and attack angle. Another way to express this is to say: Dynamic Loft MINUS attack angle EQUALS spin loft. I'm under the impression that a scientific formula is absolute.

Either way, the main point is that Fredrick Tuxen has presented that so long as impact location on the clubface, clubhead path, clubface angle, and clubhead speed remain the same, then an increase to the negative attack angle will not produce an increase in backspin. Is this in contention by you, Kevin? Or Brian?

If this is a semantics argument about adding a negative, fine. All I know is if A^A is 5 degrees downward and DL is 20 degrees the spin loft is 25 Degrees. 20 + 5 = 25. And I know attack angle alone doesnt change spin rate.

 

[Steve Hale]

If this is a semantics argument about adding a negative, fine. All I know is if A^A is 5 degrees downward and DL is 20 degrees the spin loft is 25 Degrees. 20 + 5 = 25. And I know attack angle alone doesnt change spin rate.

It IS semantics, sounds like you guys both have it right. 20 - (-5) = 25. Or, 20+5=25...Alegbraicly it is the same. Anything minus a negative is added.

So does that mean if you hit up on it the equation would be 20 - (5) = 15?

Second, for my understanding. If the only variable that changes in two separate shots is angle of attack, so speed, centerness of contact, horizontal path, vert path, dynamic loft ect. are exactly the same, but angle of attack changes, does spin rate change?

 

[Kevin Shields]

Hey Steve. Thanks, I never did well in math The spin rate does not change. Assuming center contact, dynamic loft would have to increase for the spin to change with a more downward hit.

 

[mjstrong]

Hey Steve. Thanks, I never did well in math The spin rate does not change. Assuming center contact, dynamic loft would have to increase for the spin to change with a more downward hit.

Are you sure? If you have a more downward hit, but keep the same dynamic loft, there is a greater difference between the two, ie greater spin loft. This should result in more spin.

For example: 20 DL - (-5 AoA) = 25 Spin Loft
Then: 20 DL - (-7 AoA) = 27 Spin Loft

More spin loft, more spin?

I would think given any situation, you could either increase the downward hit while keeping the same dynamic loft, or increase the dynamic loft while keep the same downward hit, and you'd have more spin in both those cases than the original...

 

[Kevin Shields]

MJ, I mis-typed. By the "same" i ws implyng the same conditions just pointed more downward. If the loft stays at 20 degrees, then hitting more down increases spin, sure. I meant to say that but just quick typed it. Steve asked if the only variable that changed was attack angle. Good pickup.

 

[mjstrong]

MJ, I mis-typed. By the "same" i ws implyng the same conditions just pointed more downward. If the loft stays at 20 degrees, then hitting more down increases spin, sure. I meant to say that but just quick typed it. Steve asked if the only variable that changed was attack angle. Good pickup.

Ok. Cheers.

 

[Todd Dugan]

I think we're all in agreement here. Thanks for the info, Kev.

I think an easy way for the layman to understand this is that when the relationship between the vector of the clubhead's movement and the vector of the normal to the clubface is the same during the impact collision, then it matters not at what angle, relative to the horizon, that that collision takes place, with regard to spin rate.

Once that is out of the way, we can have all kinds of fun discussions on how to deliver more loft with a more descending attack angle and visca versca. And then there's all the fun formulas with spin loft and dynamic loft. Substracting a negative. I must be a geek, because I actually enjoy that stuff.

But it is important to note, as this started as a discussion on the "ball flight laws", that the science of the spin rate not being altered by attack angle alone, is in direct contrast to what has traditionally been published, including in The PGA Teaching Manual.