Part 6A will cover 2-D-0 thru 2-E.
2-D-0 (Directional Factors)
Homer states that the 'perfect geometric circle' is also important for directional control of the ball. Lever Assembly is the the angle formed between the left arm and the club. Homer states that lever assembly is seldom more than an inch from full extension at impact. But as Trackman has shown, hitting a shot that is one dimple from the sweetspot causes the ball to move off line. So an inch is quite a bit.
Homer then discusses the Venturi Effect, Flight Line and Flight Path, but the big thing he's getting at is if the clubface leans forward (which usually stems from moving the hands forward), the clubface will now point out to the right. Conversely, if the clubface leans back then the clubface will now point out to the left. The golfer can make note of this as if they use 'impact hands' at address, they need to keep in mind the clubface will point to the right. Conversely, if they use 'mid-body' hands at address, then they need to note the clubface points more to the left.
Furthermore, Homer states that deviations in Horizontal Hinging can produce considerable variation in direction, but little change in trajectory (height of ball flight). For vertical hinging, variation can produce considerable variation in trajectory, but little change in direction. Angled hinging depends on the plane. An angled hinge on a flatter plane is more characteristic of a horizontal hinge. On a steeper plane, the angled hinge has more vertical hinge characteristics. I *believe* if you use an angled hinge and want to hit the ball with power, you need to swing on a flatter plane.
Homer also talks about 'seperation' which is the point after impact, just when the ball leaves the clubface or 'seperates' from the clubface.
2-D-1 lists all of the major directional factors. Most of them are easy to understand without me going into them.
2-E (Conservation of Momentum)
Objects in a linear collision cannot seperate greater than the speed of approach. - Homer KelleyBasically Homer is stating that you cannot have greater clubhead speed after impact than you do before and at impact. Physicists have recently backed this up. I tend to agree, but feeling like you have more clubhead speed after impact is a good swing feel to have.
Homer then gets into COR which is part of the 'trampoline effect' you often hear about when it comes to new drivers. For the better golf balls, the 'trampoline effect' is higher and any 'compression leakage' causes a lesser COR.
So with a good golf ball, a clubhead approaching impact at 100 mph will slow down to 80 mph at seperation. And with a lesser golf ball the clubhead could slow down to 70 mph.