Some of you may or may not have heard of the D-Plane (Descriptive Plane) written about by Theodore Jorgensen originally in 1999, but this model of physics can help us understand the laws the club and ball follow everyday during impact to create the shape and height of the ball.
There will be several articles on this topic as it applies to other aspects of the game, different areas of the game require different adjustments to the D-Plane to be successful. Wedges by nature are shorter in length and have a more up right lie angle to help us move closer to the ball, length of club and added loft to the face help us hit shorter shots that land at steeper angles with more spin. The general idea of moving closer alters the attack angle of the golf swing and significantly effect the path, the D-Plane and ultimately how the ball is launched.
The D-Plane is a physics model that was conceptualize to identify the effects a moving object has on another object at rest, such as a car accident. This is prefect for explaining the effects a golf club has on a golf ball. There are a couple terms that should be defined and understood before going further.
Face On – Perpendicular to the target line at ground level
Above – Directly above the ball and target line
Dynamic Loft – loft of the club at impact of the ball, also affected by face angle being opened or closed also called Normal of the clubface in the face on view
Attack Angle – the momentum of the center of the face as it comes in contact with the ball from a face on view
Path – the momentum of the center of the face as it comes in contact with the ball from an above view and heavily effected by angle of attack due to the bottom of the swing arc and dictates up to 25% of the total direction of the ball
Face Angle – face orientation to the target line either open or closed in relation to the target line (Normal to clubface) and dictates up to 75% of the total direction of the ball, also called Normal of the clubface in the above view
Vertical Launch Angle – angle at which the ball leaves the face of the club vertically from the target line in the face on view
Horizontal Launch Angle – angle at which the ball leaves the face of the club horizontally from the target line in the above view
Spin Axis – the tilt axis left or right that the that the ball is spinning around during the flight of the shot, positive axis ball will fall right and negative axis the ball will fall left (draw or fade)
Spin Loft – the difference between angle of attack and dynamic loft and helps measure compression of the ball (Solidness of contact)
So, this in it self is something to let sink in and draw a image of before moving on if you are unfamiliar with these terms.
The model above is applied to two views of the golf ball, face on and above the ball. From above the ball this model would produce a sizable hook shot and from a face on view we would be able to see lanuch angle of the ball. This model tells us completely different things about the flight of the ball when applied to these two angles...
Face On Perspective
- Angle of attack
- Dynamic loft
Effects on the Ball
- Launch angle
- Spin loft
- Face angle
- Dynamic loft
Effects on the Ball
- Spin axis
- Launch angle
The importance of this model and the information it produces is helpful because this tells us where the ball goes and why. There is one thing that is left out and that is centeredness of contact and the effects of toe and heel impact. This model is assuming center face contact.
One thing you may already know about wedge play is to open your stance by aiming your body and feet slightly to the left of your target for right handed players and to the right for left handed players. But, do you know why? Notice the image of Rory Sabbatini at the introduction to the article, notice that his stance is not aimed at where the ball is going. There is a reason this happens and it begins with the D-Plane. Remember the earlier discussion on wedges being shorter and the lie more up right to aid us in moving closer to the ball. Imagine what this does to the swing plane of the backswing and downswing, it steepens it significantly unlike your six iron or driver due to the length of the club and flatting of the lie angle. Now, that the club is approaching the ball from a steeper angle of attack, this has a significant effect on path. The steeper the angle of attack the further the path will run to the right of the target line for right handed players and the opposite for left handers.
The clubface is perfectly square to the path and when the attack angle is this steep with a wedge the path is running to the right of the target line. The problem with this type of wedge shot is that you will have to roll your hand through impact to square up the face of the club and this type of club interaction creates a negative spin axis (hook). This ball is drawing to the left and when it hits the green it will kick and roll left of the pin for a right hander. Wedges are best when the spin axis is as close to zero as possible, so that the ball stays online and hits with roll straight forward or spins straight backwards depending on the shot type. This is why most good wedge players play from an open stance to aid in this very technical D-Plane model effect on the ball. In Power Golf written by Ben Hogan he mentions that he played his stance with lower irons open and his driver closed. This is a diagram Hogan used for his setup positions, notice the wedge setup. Don’t start thinking about the driver yet let the wedge concept sink in and we will get the driver in the next few articles.
Now that the stance is aligned to the left of the target line the face and the path match up and from this position we can hit wedge shots with a spin axis of close to zero, which means the ball will stop faster and you will be able to control your distances easier.
“The steeper the angle of attack the further the path (momentum of the center of the clubface) will run to the right of the target line for right hander players and the opposite for left handers”
The short and long on this conversation is to open your stance (aim left for right handers) on wedge shots and fight the urge to roll you hands through impact. This will help you maximize the D-Plane and get your spin axis closer to zero, which will produce straighter flying wedge shots and help you control your distances.
Please contact me if you have any issues digesting these concepts or would like help working on improving your wedge play.