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Re: Re: Re: atn: tom guery


Posted by: Jack Mankin (MrBatspeed@aol.com) on Thu Nov 25 19:08:42 2004


>>> A further revision/adaptation of the hitting/rotational swing is the handpath hook that Jack calls "BHT".To me this seems like a whipping type action,not true application of torque to handle,but rather an enhanced acceleration of the bat due to the hooking shape of the handpath on the approach controlled mainly by the front side.Nyman's simulation shows only "reactive torque" which is extremely non-intuitive. <<<

Hi Tom

Tests we ran do not support your above statement. Pressure sensors on the bat's handle show that at contact, the top-hand is being driven forward with as much force as the pulling back force from the bottom-hand. This means torque is still a major factor in accelerating the bat-head.

Let use revisit the BHT test from the post below.
>> We then isolated the torque factor by eliminating energy transferred by the CHP. This required holding the right hand at a fixed point and only applying torque to accelerate the bat-head. While the right hand was held at a fixed point, the bottom-hand rotated forward (un-hooking) cocking the bat back about 90 degrees from contact (a heavy bag). Bottom-hand-torque (BHT) was applied as the lead-shoulder rotated back to the 105-degree position. This also produced speeds of 50 to 55 mph with no forward movement of the hands. <<

Let us suppose that in a similar test, we allowed the hands (as a unit) to arc six inches back as we cocked the bat back 90 degrees. This would allow for a short CHP and some more "hook" as BHT was being applied. Since we have not actually ran this test (hands arced back 6 inches), let us say we attained 60 mph. How much of the bat speed was derived from torque and how much from the CHP ("a whipping type action").

Let us then arc the hands back 12 inches, then 18 and then etc.(back to the launch position). At what point of this test are you saying that there is "not true application of torque to handle?" At what point are you saying that all bat speed was generated from the CHP (or hook, or whip) and torque becomes a non-factor?

Jack Mankin

##
Re: Torque
Posted by: Jack Mankin (mrbatspeed@aol.com on Sat Oct 4 19:48:48 2003

>>> Hi Jack
Could you please explain how you came up with the 50/50 RE/torque scenario. Without being too scientific, what methods did you use? In a two handed situation, not one. <<<

Hi Enloe

There are two main forces acting on the bat to generate bat speed, torque and the transfer of the body's rotational energy via a circular path of the hands. In order to isolate the bat speed developed from the CHP (Circular Hand Path) we added a steering-wheel knob to a 34-inch, 33 Oz. bat. Torque requires two forces being applied from opposing directions. The steering-wheel knob applies a single force at a single point on the bat. Therefore, all bat speed attained came from the CHP alone.

With the rotational swing, the hands travel around 22 to 24 inches from launch to contact. Following that hand-path with both hands on the knob we were able to attain bat speeds of 50 to 55 mph. (Note: Higher speeds were attained with one hand which allows a much longer CHP.)

We then isolated the torque factor by eliminating energy transferred by the CHP. This required holding the right hand at a fixed point and only applying torque to accelerate the bat-head. While the right hand was held at a fixed point, the bottom-hand rotated forward cocking the bat back about 90 degrees from contact (a heavy bag). Bottom-hand-torque (BHT) was applied as the lead-shoulder rotated back to the 105-degree position. This also produced speeds of 50 to 55 mph with no forward movement of the hands.

We concluded that with good rotational mechanics, about 50% of the bat speed came from the CHP and 50% came from torque. Pressure sensors placed on the handle of the bat support that conclusion. --- The 50/50 ratio does not hold true with more linear mechanics where as little as 10 to 15 mph is gained from the longer but straighter hand-path.

Jack Mankin


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