Phillips tells us that the amount of what I call kick back is
dependent on the amount of force that is applied at the
beginning of the casting stroke. I believe that the action of
the rod is also a contributing factor. Obviously a human is not
able to make a broom stick kick back because a normal human is unable to
even make a broomstick bend noticeably
with a casting stroke. On the other hand, a very noodly rod will be
prone to kick back and the more noodly the rod the
greater the kick back. Also a rod that is full flex in nature is going to
have a more pronounced kick back then a tip flex
rod. I find it fairly easy to make my 6 wt, 9 ft, TCX kick back a foot or
more. I can only surmise that a lighter rod with
a slower action can kick back 2 feet or more with little effort.
Does this phenomenon actually happen during real life casting? I have seen one case where this phenomenon
was captured on film. It
required the use of high definition, high speed still
photography to capture the kick back.
The cast was also captured on video simultaneously and I reviewed the
video a number of times without being
able to spot the kick back that was obvious in the still photo.
So to make my view clear - I think that for the majority of the casting
stroke constant force/acceleration is the most
efficient means to make a casting stroke. I think a smooth transition
from zero force to the constant force used in the
majority of the casting stroke is a good thing as it ensures that we
don't experience kick back irregardless of the rod
characteristics or distance being cast. This transition phase in my
opinion is on the order of 1 or 2 degrees, i.e. until
we have the rod tip moving in the direction of the casting stroke for
most casts. Even when casting with a very noodly,
full flex rod for maximum distance I doubt if the transition phase is
ever more than a few degrees of rotation. This initial
start up phase is a very small percentage of the casting stroke. If we
sustain this start up/transition phase for more
than a few degrees of rotation we end up with waves in the fly line and
this will result in tailing loops after the loop
forms.
Thanks
Walter
----- Original Message -----
Sent: Monday, May 10, 2010 10:07
AM
Subject: Acceleration (Follow up)
Walter & Group...
We have had a great deal of discussion on
acceleration in the recent past. Defiinitely worth re visiting.
Give some thought to this string of messages.
Walter Simberski promised us that he would
lend his mathematical / physics expertise to further study the topic.
He now responds. I placed his attachment with this
message. G. :
Hi Gordy,
Just getting caught up on things here. My
analysis of acceleration vs tip path is attached. It may create more
questions than it answers...
Thanks
Walter
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Walter....
Thanks
! I'll share with the Group and step back to view their
comments.
In # 4.
.... When the rod tip is at the mid
point of the casting arc it has to be significantly behind the mid point
travel of the butt section of the rod because of rod bend. So at that
point the casting arc may well be almost complete.
Still
remains, I think, that for rod tip path to be in a straight line, we need to
have application of force yielding rod bend which is matched to the casting
arc.
Gordy
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From Bruce Richards :
Hi Gordy,
I read Walters paper with interest. The only
thing I might be inclined to disagree with is his assumption that perfectly
constant acceleration would not be desireable. He asserts that we
intentionally don't accelerate constantly to avoid "kick back", and other
problems. I don't think this is the case. I've tried very hard to accelerate
in a perfectly constant way, but have not been able to do it. And I've never
seen it in others either, but did see a 1.2, which is nearly perfect, and
many casts under 2.0, which is very close to constant.
To think that big problems would occur if the
acceleration was slightly more constant isn't entirely logical in my mind,
nor has it been clearly explained why this would happen. Noel doesn't see
how this would cause problems either. *
But this is all probably just a theoretical
issue, I'm not sure that humans can achieve perfectly constant
acceleration... If I ever get to that point I'll be very proud, even if it
does cause problems in the cast and we're proven wrong!
Bruce
* Noel Perkins, Professor of Physics, University of
Michigan.
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Bruce....
Seems
we'd need some sort of casting robot programmed from the outset to yield
perfect constant acceleration to help prove the point... though I suspect
you and Noel are correct.
Gordy
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Gordy, we have the robot, but haven't used it
in a while and have not tried programming constant accel. into it. Great
idea though, we should try that!
Bruce
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