Casting mechanics

Walter & Group....

From Lou Bruno.  My comments in his text in italics    G.:

Gordy,

I was looking at the Ally?s attachment (picture), I equate RSP-3 with the completion of the forward cast (follow through).  In order to get the rod in the position for RSP-2 wouldn?t the caster use rod rotation and if so why would they?  Wouldn?t the caster stop the rod, allow the rod to counterflex and rebound, allow damping to complete, before any further rod movement?

 

Not necessarily.  As I understand it, RSP-2 was the position after damping .... I made the assumption that the caster didn't add rotation. 

 Ally sent us that overlay diagram ... but it was the work of Grunde Lovoll.  Once again, I included it in the attachment for clarity.

I understand damping to mean, the time a rod takes to stop vibrating. Is this correct, as a caster how can we control damping or minimize it? And if we do is that a good thing?

The way I see it is that damping is mostly a function of the speed with which a rod returns to its original position after vibrating .... not so much a function of what the caster does. Better, yet :

 Don Phillips describes DAMPING as "...decay of vibration amplitude in the absence of any external applied forces."

* THE TECHNOLOGY OF FLY RODS, by Don Phillips, pp. 88 - 89.

 

Lou

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From Soon Lee.  My comments in his text in italics followed by my more detailed answer :

Hi Gordy,
 
I am always the odd man out when there is a discussion on the role of straight line path on loop size.

You are not alone, Soon.
 
I am of the opinion that straight line path of the rod tip only determines a straight fly leg. It is essential to throwing a loop with parallel legs but it does not determine loop size. Straight line path is just as essential to throwing a wide loop with parallel legs. Just this latter observation alone will refute the statement that straight line path is the raison d'etre for tight loops.
 
Loop size is the result of multiple factors: 
1) extent of rod bend at the "stop", a product of rod stiffness and caster performance;

Yes.... rod bend related to application of power as well as stiffness.

2) profile of the rod bend at the stop (whether rod counterflex is largely directed forwards, or counterflex is directed more downwards);
3) the degree of abruptness of the stop (Lefty's speed up to a stop....);

Yes.

4) purposeful manipulation of the rod tip by the caster at the stop: stiffening up the rod shaft by thrusting along the axis of the rod (Lefty's stab) moves rod bend distally, shortening effective rod length with consequent reduced rod bend....Bruce Richards points out that a shorter rod casts tighter loops. Alternately purposeful, exaggerated rod rotation at the stop widens loop size.

Agree. 
Loop shape has its own causative factors, but that is another story.
Yes. 
Soon S. Lee.
 
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Soon : 

Well, a straight fly leg IS needed for a small loop, so one could still argue for a straight (almost) line path of the rod tip... at least for THIS COMPONENT OF THE SMALL LOOP.

What the caster and rod do after Rod Straight Position, largely determines what happens to the rod leg of that loop.

In other words, we can have a straight line path of the rod tip for the "start" of a small loop, then have the rod unload with the tip at RSP close to the oncoming line and end up with that small loop ..... OR.... the caster can have that straight line path (SLP) up almost to RSP and then unload finally at RSP well below the oncoming line and end up with a larger loop.

Actuallly, that would be placing some brief increase in convexity of the rod tip path prior to RSP.

OR...

We could have a SLP of the rod tip all the way to RSP and unload just beneath the oncoming line and still end up with a wide loop if we have a great enough descent of the rod tip immediatelly afterward by virtue of great conterflex combined with insufficient loop speed to erase ("suck up") the descending wave produced by that move.

Point is, I think you are correct that it is NOT merely a simple matter of rod tip path during the stroke that always ends up determining loop size .... However, I feel it is usually the principle determining factor.

Gordy

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