I've had that book for many years and I have a few questions for real world applications just for my own desire. The difficult part of explaining this to people is that there are many assumptions that must be made. Not that they're not factual, but they must be discussed. The assumption that I see the most from the posts I have read is that the ball is hit before low point on the plane. While this may be true for any good iron shot, it is not necessarily true for shots hit off a tee. In fact, as I'm sure most of you would agree, carry distance on a drive is maximized by an upward hit. This is obviously after low point and no longer an inside out true path and encourages shots that go left. While this information is useful, without extremely powerful technology like a trackman to tell a person what their attack angle was on any given shot, it is hard to make an accurate assesment of the true d-plane for the shot. (I'm assuming of course that none of us can tell if a player had a 2 degree upward attack angle vs. a 0 degree attack angle just by watching with the naked eye. Maybe we can see big differences but not small ones). Without knowing the exact attack angle, we are guessing on the true orientation of the face relative to the true path. So my first question is, without exact data or the skills to produce exactly the same attack angle for each of our shots aren't we all just fudging the numbers a little bit? Yes, everything I see has lots of validity and is great information but how useful is it to the majority of golfers?
My next question deals with the shaft lean topic. This is something I haven't cleared in my mind yet. Can someone tell me why it is safe to assume that more forward lean in the shaft automatically means more in to out true path? From my above thought, it seems appropriate that with a driver there is some shaft lean on a drive with an upward attack angle and that isn't in to out. Secondly, isn't is possible to maintain some amount of shaft lean into the finish that would alter its actual low point? Thirdly, can't a person completely change the low point of the swing by other means(such as improper weight shift) to again alter the low point. (clearly, this last one wouldn't be recommended but does happen).
As with most things in golf, it comes down to plane and face angle. For the writer looking for clarity. To understand the d-plane you need to be comfortable with the shape of a circle at an angle. Anytime you hit a ball before the low point, relative to the ball, the club head is moving in to out because of what a circle looks like at an angle and anytime you hit a ball after low point, relative to the ball, the clubhead is moving out to in. in other words, if you take a dish and hold it to an angle to the counter, relative to the part of the dish touching the counter the "backswing" side of that dish is above and inside of the part touching the counter. For upward hits, the "followthrough" side of the dish is above and inside also so the club head is constantly moving down and out to low point than its moving up and in after low point. so if the ball is hit before low point, the club is always moving down from in to out, relative to the ball, and if it's hit after low point the clubhead head is moving up from out to in, relative to the ball. The key here is relative to the ball, NOT THE TARGET. After that, it's face orientation relative to the true path of the clubhead. The key is forgetting what has been told for so long that path determines initial start and face determines curve. While that makes sense its not accurate. clubface orientation relative to the true path determines both starting direction and curve.
From my understanding, the graph that is shown can be explained this way. the line at the bottom is the tangent to true path when ball comes off the face and the rising line is the club face orientation(normal to the face blah blah blah) when the ball comes off the face. if the two lines are on each other you have a striaght shot in the direction tangent to true path after seperation. if the angled line is right of (or open for right handers) the bottom line you have a ball start right and curve more right. Opposite for left but I think you get the message.
If you're still confused cut out at right triangle(triangle with one angle at 90 degress) from a piece of paper. place it on the table with the hypotenuse(sp? or long side) angled off the table. the piece of the triangle on the table is the tangent to the true path line and the hypotenuse is the club face orientation. Standing it straight up will show you the 3-dimensional look of a d-plane straight shot. looking at it from straight on the hypotenuse(in other words the skinny part width of the paper). After that start move it around to see how it changes. pick an imaginary target, rotate the triangle so it doesn't point at the target and tilt the triangle so it's not on top of it self. Hopefully that helps. of course, different clubs will have different amounts of rise in that hypotenuse angle based on their loft and so on...
If i'm wrong with any part of my description, please help me and let me know about the question s i have.
