Thank you for clearing that up. I didn't know. Does it only measure ball flight and spin? Does it measure Shaft Angle at Impact or is it a calculation?

http://trackman.dk/Products/TrackMan-Pro.aspx.

Ya, Ive been to the website but they won't tell me. I was hoping that you would know for sure.

Dynamic Loft*
Spin Loft*
Face Angle*
Total Distance*

These are the interpreted numbers the other readings are measured. Obviously total distance cannot be measured since the ball is running along the ground.

Face angle is the concern. Homer wrote the ball leaves the clubface at essentially right angles. Jorgenson wrote (D plane) the ball curves away form the path. If you hit the ball with TM reading zero path and zero club face the ball flies dead straight. I have confirmed this with my own eyes/swing.

I'm confused. You said that face angle is interpreted. But in the last paragraph you said that zero path and zero clubface = a dead straight ball. Don't you mean to say that when the ball goes perfectly straight, that TM interprets this as zero path and zero face angle? I dunno?

Oh, you are saying that face angle is measure by TM Radar. Oh, I thought that it had only one radar gizmo behind the ball. It has 2?

Correct I was not clear - when the ball goes absolutely dead straight (zero curve) - TM will read 0 path 0 face angle. You really need to experience it for yourself. Sean Foley wants his players to swing 3 degrees inside out with a clubface roughly 1.5degrees open. Results in tight little draw at the target.

Wow, interesting stuff. I watched the videos on the TM website. When they say "Path" they are talking about "Plane Angle" meaning that a Steep Plane might be 3 degrees inside-out and a shallow plane might be say 5 degrees inside-out. They aren't talking about the Clubhead crossing the "Plane Line".

I can picture what you mean but, picking some numbers from the top of my head, if impact interval is 0.1 sec and the clubhead closes 3 deg in that interval, then the clubface/ball is rotating at 5 rpm. Is that small rotation enough to cause a Venturi/Magnus effect to cause a draw? Even if I am off by an order of magnitude and impact interval is 0.01 sec, then rpm is 50. Same question. I would think that hundreds or even thousands of RPMs would be needed to cause the ball to curve.

I believe that the line of compression, relative to the vertical centre line of the ball is what will determine the amount or absence of curve.

You've got a point there, 3putt.

It will probably just be draw-ish. Perhaps it makes a slight difference to where the ball goes when it bites the green. Perhaps it makes a small trajectory difference with a driver and not with a middle iron. Don't know really, but I guess it is practically straight.

Personally I like to see a hint of a draw in my stock shots. If I also see a divot that is reasonably shallow I know that the ball compression is good.

Assuming a centered hit, if the club face angle at separation is at the target and the direction of the club head after separation is right of that direction, the ball will draw. No question.

As far as trackman goes, it calculates face angle based on initial launch conditions. Using impact tape and a knowledge of gear effect and D-plane, ball flight can be explained quite nicely. Vertical swing plane is measured and has nothing to with the shaft plane angle. It measures the movement of the sweet spot relative to the ground.