[Daryl]

I like what little I know about Trackman , dont get me wrong. If it doesnt measure it as of yet, I'd imagine it will in the future.

Trackman measures Ball Flight with Doppler Radar. Only "Ball Flight". It uses "calculations" to report Spin Rate. That's why you need to tell Trackman the Club that you're using is a 6 Iron. What happens if you punch in "4 Iron" and used a "6 Iron"?

D Plane Theory doesn't use the concept of Hinge Action, Line of Compression, etc. It recognizes "Moment of Inertia" of the Ball as a "Listed" factor in "Effective Loft" but the connection to this "Advanced Level" of "Ball Control" is ignored because it isn't the primary purpose of "D Plane".

Factors Affecting Drag, Lift, and Spin (Page 83)

It is of interest to consider factors by which the golfer may reduce the spin of a ball and thereby reduce the drag and lift of the ball. One way is to reduce the effective loft of the club. This may be done by choosing a different club with less loft.

The Effective Loft of a Club (Page 81)

The effective loft of a club moving toward the target and striking the ball will usually not be the loft of the club. The effective loft of the club will be the angle between the normal to the face of the club and the velocity vector of the clubhead in a vertical plane containing the ball and the target.

The effective loft of the club, EL, depends on several factors. If the golfer is using a club with a flexible shaft, the effective loft of the club will depend on its flexibility and on any peculiarities in swinging the club. We shall not attempt to analyze this factor. Golfers have expressed their sentiments in this matter by saying that they want stiff shafts. One aspirant for the tour said, "The stiffer the better." The effective loft of the club depends on whether the clubhead at impact takes a divot. If it does, the velocity of the clubhead at impact will be at some angle below the horizontal, and the effective loft will be decreased by this angle. When these two factors, the stiffness factor and the divot factor, are omitted from further discussion, any effect of these two factors may simply be added to or subtracted from the effective loft EL.

Neglecting these factors, the effective loft of a club may be shown to be given by the expression EL=L+a(i)-,B(i)-y, where L is the loft of the club, a(i) and B(i)are a and B when the clubhead is in contact with the ball, and y is the backswing angle of the arms (see Fig. 2.3). The angles a(i) and B(i) will be determined by a calculation for each individual swing. We shall see that these angles depend on various characteristics of each swing.

The effective loft of the club is one factor in determining the spin of the ball, its rate of rotation. When a club with zero effective loft hits the ball, the ball leaves the clubface with no spin. When the effective loft is greater than zero, there is a complicated interaction between the club and the ball that depends on the friction between the two surfaces, that of the ball and that of the clubface. It also depends on the elastic properties of the ball, on the moment of inertia of the ball, and on the clubhead speed.

One more comment about "Spin" and "Friction". I borrowed this from 'Dave T's Club Design Notes'.