Ok. To be more clear, I should have said impact separation would be on the target line. Fair enough.
The reality is that the impact separation line is not parallel to the low point plane line.
Here are a couple pics:
It's quite possible that I am using the phrase plane line incorrectly. If the ball is struck before low point under all the conditions you mentioned, the direction of the club into the ball is to the right of the low point plane every time.
Hopefully the pictures help and if my use of terminology is incorrect, I do apologize.
Thanks for your drawing. Despite your statement that "the Clubhead is still moving downward, outward and forward" through Impact -- words I have lived by for many years and which led me to believe we referring to the same geometrical model -- it is now evident that we're talking 'apples and oranges'.
As you have indicated, we have an entirely different conception of the term 'Plane Line'. Until we come to grips with that, we have no business attempting to differentiate Impact versus Low Point Plane Lines, much less Square versus Open or Closed Plane Lines.
To wit:
You have illustrated an Open-Open Plane Line (10-5-D). Not being familiar with your model and terminology, I assumed a Square Plane Line (10-5-A), i.e., toward the Target. With the Clubface aligned per 2-J-1, this will produce a "Push" Line of Flight (see Photo 10-5-D and description in 11-5-D). Hence, the "straight shot" result you referred to in your post. But, in reality, it is a 'Pushed' Shot to the right of the Open Impact Plane Line (and its parallel Low Point Plane Line).
I guess all I can do here is ask you to define what you mean by "Low Point Plane Line"? Then, maybe we will be better able to understand one another.
Here's the way it looks in my world:
In every geometrically correct Stroke, the Clubhead Path from Impact to Low Point -- assuming Impact occurs prior to Low Point -- is 'Inside-Out' (relative to the Impact Plane Line). This is true even with an 'Outside-In' Stroke (Plane Line Open to the Target Line) because Impact and Low Point are on the same Plane and that Plane is Inclined. It matters not how the Base Line (Plane Line) of the Plane intersects the Target Line, i.e., Square, Open or Closed.
Then, because the Low Point Plane Line (tangent to the Circle) is Down Plane from the parallel Impact Plane Line (chord to the Circle), it must always remain 'outside' it, never 'inside it (again, assuming a geometrically correct Stroke, even when that Stroke is 'Outside-In'). Therefore, with a Square Impact Plane Line, the likewise Square Low Point Plane Line can never point "left of the target".
So, summarizing the procedure I thought we were dealing with, namely:
1. A Square Impact Plane Line, i.e., one that is aligned to the Target;
2. A ball positioned on that Impact Plane Line and prior to Low Point (and thus struck on the Downstroke);
3. A parallel Low Point Plane Line located, by definition, Down Plane from the Impact Plane Line; then . . .
The Low Point Plane Line can never point left of the Target Line.