Wednesday, December 23, 2009

Zeroing Out The D-Plane Video

Presented by Brian Manzella and Kevin Shields.

Here Kevin has an attack angle of -3.8* on this shot.

In order to zero out his 'true path' he would need to swing left by *about* 1/2 of that attack angle. So to get a true path of 0*, Kevin would need to swing left (aka, rotate the plane line left) by about 1.9*. In this case he moved the plane line to the left by 2.7*. This has created a true path of -0.3* (outside-to-in).

His face angle at impact was at +0.5*, which means it was open by 0.5*.

So, why does he hit the ball dead straight here despite having a clubface that is open and a clubpath that is 'outside-to-in?'

For starters, the new ball flight laws state that initial direction is mostly due (about 85% due) to the face angle. So, 0.5* open is not very much at all so that helps the ball start off a hair to the right of the target. However, path is 15% due for the initial direction. So while we have a 0.5* open clubface, the -0.3* path cancels that out.

The other reason the ball goes straight is that 0.5* and 0.3* are very miniscule numbers. So add everything together and you've got a swing that 'lit up trackman like a pinball machine' and you get a straight golf shot.



Kevin said...

Fun to watch. Kevin Shields is a PLAYER!


Rich H. said...

Great player, great teacher. Always a helpful guy.

Anonymous said...


Do you understand the physics of the D-Plane? Here's what confuses me: I doesn't make any sense that the "angle of attack" -- which I take to mean the angle with which the face approaches the ball relative to the z-axis (gravity vector) could affect the left-right spin.
Two ways I think about it:

1) Imagine a right handed golfer approaching the ball from 0 degrees (i.e. neither "coming across it", nor "pushing out at it") with a negative angle of attack. Then imagine the same thing from a left handed golfer. From the ball's point of view, these are the same. But the D-plane discussion seems to be saying that in one case the ball would spin one direction (i.e. a right handed draw) and in the other case the other direction (i.e. opposite, a left handed draw)

2) Or in different terms, how can the ball tell which way to spin for a descending (or ascending) club?