Walter & Group..........
A brief but important message from Troy Miller :
Please understand, y’all, we do NOT have to stop the rod (either rotationally or rotationally) to cause the rod to unload or to initially form a loop. If we fail to continue proper accelerations of the rod, then our system comes to a point of steady state motion. Since the rod has potential energy stored in it from loading, it will want to release this energy if we fail to maintain accelerations.
So, we don’t have to stop to unload or make a loop. All it takes is failure to maintain acceleration.
Regards -- TAM
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Troy,
I agree ! This explains how we can still have loop formation even though as mere mortals we really can't bring the rod butt to a, "brick wall stop". It also explains why casters who have a soft, "mushy" slow-down rather than an, "almost stop" still have loop formation even though the loop may be far from ideal.
One can demo a true complete stop of the rod butt by casting next to a rigid object and having the cork handle actually collide with it. All kinds of things happen including nasty waves in the arms of the loop. Not pretty. Dean Floyd (MCI) demonstrated this at the last conclave very effectively. (As you may know, Dean is a superb, "trick caster".)
When we fail to continue acceleration at the end of the stroke, the rod tip does unload its energy by doing the one thing it can.... STRAIGHTEN. Once that happens, the line overtakes the rod tip and we have loop formation.
Without that rod tip dipping down a bit just prior to RSP, that "overtaking" would result in a collision between the line and the rod tip.
Several years ago, I was the caster while Lefty was teaching one of his effective yet oversimplistic ways for the students to get a tight loop. He said, "Try to throw the line at the rod tip". That usually works. I purposely did just that with no dip in my rod tip and the line hit the tip. Made for a good laugh by all.
Gordy
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I look at Walter Simberski as our, "resident mathematician". This from him :-
Gordy -
Maximum tip speed is always at RSP and exactly at RSP. As long as the rod is bent it is exerting some amount of force to pull the rod tip (and line) to reach RSP. As long as there is any force applied the speed will increase.
You are 100% correct that some of the force will be directed downward. It's inevitable because the rod butt has been rotated past the vertical position. Without getting hung up on quasi static rod dynamics and external forces you can easily determine the exact direction that the force is pulling the rod tip/line at any instant in time by examining the point of impact (many many thanks to Joan Wulff for that concept) up to the point of RSP. This results in some loss of energy being imparted to the line but it is necessary to form the loop. It's also necessary to keep the line from crashing into the rod tip.
If the casting arc was exactly 180 degrees the rod tip would be reaching its maximum speed at the same point where the forward velocity is zero. This is one of the reasons why it's so important to understand the difference between speed and velocity.
Cheers
Walter
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Al Crise relates power to the Belgian cast: