[12 piece bucket]

Ok Great. So am I understanding correctly that the impact plane line is of the ball and not the club head?

Seems strange. Hopefully, I'm misunderstanding.

ABSOLUTELY . . . that is what is impacted no? The ball would always be on the impact plane line . . . low point plane line and impact plane line get farther apart as you move the ball more back. as a result the angle of approach (and angle of attack in 3D) become more acute with angle of approach being defined as the line that connects impact point and low point. . . low point plane line and impact plane line would be the same if the ball is struck at low point . . . this is the only time impact would result in a tangent . . . impact plane line would be above the low point plane line if the ball were struck after low point . . . but still be a chord and not tangent.