[cometgolfer]

Martee,

I think the 2-dimensional aspect of the diagram is deceiving. It seems that it you were viewing this from the golfers visual perspective, then the green line would be the base of the plane and the blue line on the "bottom" of each diagram would represent the "top" of the plane (as if it were sliced parallel to the ground). That would make the inclined plane the 3-D area between those 2 lines. The line you show as "clubshaft travel" is more like what the clubshaft itself would look like, the gray bar would be the clubhead and the red dot the sweetspot.

In that case is would seem like the shaft would indeed lie on that inclined plane along with the sweetspot of the clubhead.

Not sure if that makes any sense, and my description wouldn't be exactly to scale, but that is how I interpret it.

Comet