4. The left arm swing plane line, flip release. (pivot-controlled procedure) (The first I'd heard of this left arm swing plane line.)
See 10-6-D / Turning Shoulder Plane / '-B Version' (Vertical Left Arm Swing Plane).
Here:
The arms hang at Address and move in a simple back-and-forth up-and-down straight line path while utilizing the Throw-Out Action of Accumulator #3 [Left Arm and Clubshaft Angle] to 'flip' the Club 'on plane' past the Hands at The Top and 'in-line' with the Hands at Impact.
As always, remember that the selected Plane Angle (and its Base Line) is independent of the employed Release (10 / A-F).
"Also, what is the significance of the clubhead moving above plane with momentum after impact with the angle of approach for swinging?
That's apparently been omitted in the 7th edition.
What compensation is required? Automatic? Is it a drawback?"
Hybrid Mode
