Posted by: tom.guerry (tom.guerry@kp.org) on Thu Nov 11 09:09:58 2004

My understanding of Jack's definition of "launch" is when the forward turn of the shoulders starts the "CHP".This is a useful definition in the sense that it correlates with a video landmark.

My personal theory is a little more complicated (most would say excessively complicated,feel free to ignore).My description does not correlate as directly with video because much has to be inferred from other actions which are reactive,or at least proxies for what is theorized to be going on.

On the other hand,I find things like BHT/THT/CHP also useful,but they are also proxies/indirect/not easily demonstrable on "surface" video only.

Therefor,another way to think of "launch" is in terms of when the bathead/center of mass leaves the arc of the handpath which is when it triggers momentum transfer from the (hopefully) energized torso.In this case if there remains a good CHP,the rotational component of the swing remains uninterrupted and is directed toward swinging the bathead out (developing angular acceleration of the bat) as opposed to wasting energy moving the whole bat through space (so-called "translation" or "dragging the bat" along its longitudinal direction).So,this is another way to think of "launch" more purely in terms of bat motion as opposed to what the body is/has to do to accomplish effective bathead acceleration.

This second type of "launch" would happen after the first definition.In more detail,what I suspect happens is that a good "position" (actually ongoing sequence of body/parts/positons)can be seen at the time the "CHP" starts (Jack's "launch" and therefore "launch position).Then the body continues to crate coil/separation for a bit as the hips open faster and in a slightly different plane from the shoulders.This creates a dynamic quick stretch,the time course of which is much more importan than the absolute degree of stretch/coil/twist/torsion/separation.This permits anefficient/?optimal full energizing of the torso/reversal of torsion which will then transform preferentially into batspeed if the swinging of the bathead (center of mass of the bat) is well timed to demand the available momentum.

Determining when this unloading type launch happens depends on a number of different landmarks.SOme of the best ways to pinpoint it include when the back foot gets onto the toe,but before any drag and when the center of gravity has bottomed out just before the hips go "up" (bow-arch of spine helps drive unloading/untwisting).