[Martee]

If we are to accept 2-N-0 where the Sweet Spot Plane Line has been redefine (herein) to the Impact Plane Line which lies on the Sweet Spot Plane along with Low Point Plane Line, we discover that the Sweet Spot will pass through the Impact Plane Line (Plane Line) once on the down stroke and once on the up stroke, whereas it only passes through the Low Point Plane Line once.



In the event I misunderstood your post and it was to say I should extend a line downward...

I did just that when attempting to model it in real life.

What I discovered was that the 'roll' that the swinger employs during start up and initially in the backstroke does indeed pull the extended line (sweet spot plane) to the inside for Diagram 2. As for a hitter who doesn't employ an intentional roll, it stayed on line, Ah-Ha, oops in the initial modeling I used a fix point at the top of the club shaft(grip). When the fix point moved, then so did the line for diagram 2 again.

One simple way to prove or disprove the the diagrams, etc. is to use either a vertical or horizontal plane instead of an Inclined plane. By doing that it removes one component of the motion, either In (Vertical Plane) or the Up (Horizontal Plane). Basically making this a 2 dimensional model initially, removes complexit. Then add back in the 3rd dimension by using an Inclined Plane.