The String-Bat Model ver. 1.1.1
By: Jack E Johnston
March 31, 2012
In the latter half of the 1970s, I developed the “String-Bat Model” for hitting softballs. My team had me batting in the clean-up position; I was their big hitter. The String-Bat Model is equally applicable to baseballs.
The String-Bat Model is very simple. What can be done to a string to hit a ball? Any bending moment will only bend the string. The only motion available is to pull on the string. Thus the “String-Bat” is put in motion by rotating the hips and when the bat is at belt level or level, pull on the end of the String-Bat toward center field and make contact with the ball. Skill comes in learning how fast to rotate the hips to start the String-Bat in motion. Too fast of a start of the rotation, and the String-Bat will pass the point where the end of the bat can be pulled to center field, and the bat will un-cock the wrists and the swing will fail to develop full velocity. The hips must be rotated with a constantly increasing acceleration so that when the String-Bat reaches level, the hands can pull the end of the bat towards center field. Too slow a rotation, and the ball will pass before the swing develops. It is best to start with a slow rotation and gradually increase the speed coordinated with the pull to center field. As a feedback, it should feel like you are pulling on a 25-pound bowling ball. The belt buckle should end up facing center field. Anything learned slowly can be produced fast with practice; start slow to develop the coordination, and then slowly increase the speed of performance.
There are three variations for hitting the ball. 1) With the back facing elbow held level (horizontal), a hard hit line drive will result from the String-Bat Model swing. 2) With the rear facing elbow lowered, a deep hit fly ball will result from the String-Bat Model swing. 3) Aim to put the centerline of the bat at a half inch below the center of the ball with a level or 10-degree. launch angle, and significant rotation will be imparted to the ball, giving it lift to travel 100 feet or so further than if there is no rotation on the ball (Fig 55, ref. 1). Aim a little lower for fastballs than for curveballs.[i]
Stance: The feet are placed at shoulder width and are fixed in place. It is not recommended to lunge to hit the ball, as the bat is better placed on the ball with no change in the position of the batter relative to the path of the ball.
The physics behind the String-Bat Model is equally simple. As the centripetal acceleration is increased along the axis of the String-Bat, the velocity at the end of the bat will increase as the square of this increase in acceleration. Thus, if the acceleration towards center field is doubled, the velocity at the end of the bat will increase by a factor of four. If the acceleration towards center field is increased by a factor of four, the velocity at the end of the String-Bat will increase by a factor of 16.
The Babe Ruth Power Swing: Point the lead foot toward center field. Rotate the hips so the belt buckle is facing center field. Pull on the end of the bat towards center field. Put the bat on the ball.
[i] Robert G. Watts & A Terry Bahill, “Keep Your EyE on the Ball” The Science and Folklore of Baseball, W.H. Freeman and Company, New York, 1990, Page 147.