Posted by: tom.guerry (tom.guerry@kp.org) on Sat Nov 6 15:24:46 2004

The personal swing model I have in mind is probably somewhat different than the details
discussed here.You might want to consider this if you set up a model.See comments after
the replies below.


> 2. Is "dog hitting the end of the leash" an example of whip?
> According to Paul Nyman, it is. If so, where is the rotation?

My interpretation of Nyman's double pendulum
(not what he actually says or means-by any means) is that the double pendulum can be
thought of as a simple 2 segment whip.See:

http://www.maths.tcd.ie/~plynch/SwingingSpring/doublependulum.html

when the second pendulum accelerates,the first pendulum decelerates (actually reactively
stops and turns back the other way).swing would be like lead arm is one pendulum and
bat is another.BHT is a slightly different concept more akin to the "hooking handpath"
which creates this momentum inertia transformer step-up thingy which can finely control
the time and place the bathead reaches terminal/escape velocity where torso turn and
handpath stop(nearly-which is where the dog hitting end of leash might apply as first
pendulum decelerates to a stop) as bathead (bat-second pendulum) swings out to
contact.As contact is approached,the bat is more and more purely driven by the
rotational/connected component and is less and less got anything to do with torque/ the
top hand apllying any force (ideally)-top hand more and more along for ride,dynamics
more and more purely like 2 segment whip.Doesn'y matter if the top hand releases at/
after contact because it is no longer contributing anything at contact.

Torque is most important in moving bat as body coils and begins to uncoil-before and at/
shortly after launch.The desired arm/shoulder action turns the bat while retaining the CHP
as lanch gets underway.

This begs the question what is coiling when ?

I would say maximum coil is roughly/heuristically just before the bat is pointing straight
back to the catcher.Somewhere closer to this than to the earlier position when it is
pointing straight behind the hitter. Tre THT torquing force applied to the handle pre-
launch AND still at "launch" (as shoulders start to turn handpath which is still while body
load coil is underway,coil not maxed out yet) assist in creating MORE body coil/twist/
torsion (absolute degree of twist is far less important than time/dynamics of twist which
should have a last quick bit of stretch then quick reversal) and keeps the hinge angle from
narrowing.Angle between lead arm and bat will want to narrow when uncoiling/unloading
happens,BUT this would delay firing out bathead when twist/torsion of body unloads
which would slow the swing prevent bathead from demanding transfer of momentum out
of torso.So torque applied at handle before and at launch is very important until hooking
of handpath on approach to contact/BHT takes over.
>
> 3. Is "snapping a towel" an example of whip? If so, where is the
> rotation?

Whipping happens pretty much purely in a 2D plane in this type model.You are creating
the momentum with your body/hand and you form a loop with the towel which you whip
by reversing your handaction and decelerating the heavy mass proximal body parts.Towel
whips like an infinite amount of segments where the loop shape provides leverage so there
is ongoing lowering of mass in motion and more velocity in mass still moving.Tip of wet
towel can exceed speed of sound and crack.Apparently the mathmatically inclined can use
calculus as a way of analyzing this infinite segment type loop/whip.

You might consider moving this discussion to hitting-mechanics.org where graphics and
perhaps Nyman's direct participation could occur.
>