Control Your Swing Plane
by Louis Esselen
(Golfswingfeeling.com)
The amount of uprightness or flatness that you create with your swing plane is determined by how far you stand from the ball. This can be measured by how far your hands are from your body at address.
After address has been taken, your upper left arm is responsible for whether you are going to swing upright or flat. Should it leave you chest early in the back swing you are going to have an upright plane. If it stays glued to your chest then the plane is going to be too flat.
Striking a happy medium and allowing your upper left arm to stay close to your chest till halfway in the back swing then leave the chest, will give you a good swing plane which will neither be too upright nor too flat, but just perfect.