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James' front page on fly and line

Moderator: Torsten

George C
Posts: 342
Joined: Thu Mar 08, 2018 7:30 am
Answers: 0

Re: James' front page on fly and line

#11

Post by George C »

Hi Merlin

Rubber chickens aside, this topic interests me. For the sake of discussion I'd like to pursue it a bit more.

As I understand your posts above, adding mass to an aerodynamically inefficient fly will help it turn over better when cast on a lighter line. I'm curious, however, as to what other positive and negative effects the added mass may have during the rest of the cast. In particular, what are the reasons the cast breaks down as flies become too heavy for the line?

If I was smart I'd stop here and wait for an answer, but being an idiot I'll flush out my confused thoughts and see what else I can learn.

Prior to turnover the drag of a bulky light fly presumably adds tension to the fly leg and saps some momentum from the system. I assume that adding weight to the fly does not change the drag but adds additional momentum to the system thereby reducing the relative effect of that drag on fly leg momentum. With more momentum and similar drag I can see how the system might cast further (assuming the rod/caster can handle the added weight of the system). I'm also guessing that fly drag has some benefits by creating some fly leg tension and helping keep the line straight in flight and this effect does not change even if the fly weighs more. Or does it?

With light lines and heavy flies does a situation arise where the fly and line have to be considered distinct (even though connected) systems? Even earlier in the cast than turnover can the fly can start to overrun the line, dragging leader and line with it out of the line path and increasing drag/air resistance on the entire system. I can see this killing a cast. Is this the main mechanism whereby light lines and heavy flies fail? Or is there something else going on even before that point? As the fly leg "tows" a fly it follows a line path that (at least in my casts) is not straight. If the fly is heavy and has significant momentum itself then I'd presume it is trying to travel in a straight path but the line has to keep pulling it into the curved line path. Tension must develop (and disperse?) as this happens. Does this sap momentum from the fly leg and cost distance (or is the total momentum in this fly/fly leg system conserved in some manner)?

And what happens during turnover while false casting with a heavy fly? Does the greater mass result in more kick or dangle which in turn require trajectory/arc adjustments or other constraints (bigger loops?) that in turn limit the cast?

Finally, I assume any benefit is dependent on how much weight is added. Presumably a little goes a long ways (and a lot may go even further but is no longer fly casting). But what determines how much weight is too much? Obviously the available mass of the line carry (as James points out) is a major factor. But is it just line mass or is distribution of the mass over length a factor? Does a 30' head that weighs say 300grains carry a heavy fly better than a 60' head that weighs 300grains? If so, why? Is there also a component of glide at the fly level? Which then raises the question of what is Gary using to decide what is the right amount of weight to settle on while he is throwing flies around his tying room?

Enough (or more likely, too much). But thanks for any insights people can offer.
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