NEW (Launch Direction Dictated by...) CHART from TrackMan Conference

[Michael Finney]

From JAGR....Journal of Applied Golf Research.....Dan Parks interview with Fredrik Tuxen:

*Fredrick Tuxen is the inventor of the Trackman™, which is a radar-based technology that tracks 3D ball flight and club movement . He is also CTO at Trackman A/S, a Danish company that develops, manufactures and sells 3D ball flight measurement equipment used in sports. To better illustrate some of the points he makes, we have included several tables and illustrations.

JAGR: In the PGA Manual of Golf it states that with greater club head speed the ball's starting path will move somewhat closer to the swing path line but will always fall in between the face and path direction favoring the face angle. In published documents you disagree with this cause-effect relationship and the ball flight laws that have seemingly been written in stone for many years.

Tuxen: With the “old” ball flight laws it is also stated that with higher club head velocity the greater is that vector force moving the ball's starting direction closer to the swing path line. We have found through launch monitor research using Trackman™ that the launch direction (LD) is in a proportion of 85 % face angle and 15 % club path.

JAGR: No matter the club head speed?

Tuxen: More or less. For iron shot the face angle dictates around 75% of the launch direction, so still heavily biased toward the face.

 

[birdie_man]

Roughly 60 to roughly 90 from wedge to driver. Easy to remember, I like it. Thanks BDAWG.

 

[Todd Dugan]

So, more loft, more pull towards path direction. Explains perfectly what I have recently observed upon close examination of the starting direction of greenside "flop" shots, when the clubface is very open to the path direction. With good friction between between clubface and ball, aided by fresh/sharp grooves and urethane-covered ball, it seems around 60% clubface. I had been looking for more like 75%, but kept finding that it was actually lower. Now its confirmed. I've been advising my students to use a simple 2:1 ratio when opening the clubface around the green. In other words, the path direction should be twice as far leftward of the Target Line than the Clubface is open to the Target Line. But of course, you must "read" the lie and favor the clubface more as friction is reduced from grass. You won't read THAT in "Secrets of the Short Game".

 

[Brian Manzella]

This is from Paul Wood:

"To answer your question, as club speed increases, the percentages will go down a little bit. So yes, higher clubhead speed will make the ball launch closer to the path. I don’t know that I have a well-defined limit curve for that, but the effective friction between the club and the ball will go up because the force between them is going up. So, at one end, if you had almost infinite club speed, the ball would launch in the direction of the path, and at the other end, with almost no speed, the ball will launch almost entirely in the direction of the face (for example, this is the case for putts)."

 

[spktho]

This is from Paul Wood:

"To answer your question, as club speed increases, the percentages will go down a little bit. So yes, higher clubhead speed will make the ball launch closer to the path. I don’t know that I have a well-defined limit curve for that, but the effective friction between the club and the ball will go up because the force between them is going up. So, at one end, if you had almost infinite club speed, the ball would launch in the direction of the path, and at the other end, with almost no speed, the ball will launch almost entirely in the direction of the face (for example, this is the case for putts)."

Makes perfect sense. Using this explanation, the amount of compression of the ball against the club face would also be a factor.

 

[savydan]

Right. As clubhead speed increases, not only does the shear force increase, which causes spin and would want to move the launch to the path, but the normal force increases as well - the force that wants the ball to come straight off the face.

I'm thinking that the coefficient of friction between the ball and the face may increase slightly with clubhead speed, but it's mostly a function of the surface properties of the ball and clubface themselves.

I think the thing to keep in mind is that we are dealing with relatively small differences in speed. An amateur's 75 mph 5-iron vs. a pro's 95 mph or whatever. I don't think we need be too concerned with 20 or 300 mph speeds.

 

[mjstrong]

So, so far, relative launch angle (I would imagine vertically as well as horizontally) is a function of spin loft and clubhead speed (even if clubhead speed is only a smaller influence).

As Spin Loft increases, path influence increases. As clubhead speed increases, path influence increases.

Would those statements be correct?

 

[spktho]

So, so far, relative launch angle (I would imagine vertically as well as horizontally) is a function of spin loft and clubhead speed (even if clubhead speed is only a smaller influence).

As Spin Loft increases, path influence increases. As clubhead speed increases, path influence increases.

Would those statements be correct?

Yes, but as savydan stated, the velocity changes as applied to golfers is negligible.

 

[Michael Finney]

Tuxen saying "more or less" and paul wood discussing theoretical infinite speeds make me think that savydan is correct....within our capacity, speed does not have that much influence