Loops, Legs & tension

I just read Ally's. I have to agree the loop does not pull the fly leg along. The fly leg is the Mass that has the movement= Kinetic energy. The loop is a change of direction of the line. In doing so it will use the energy of the fly leg.

The rod leg is still moving forward when we shoot line so it too has energy moving away from the rod. This loop of change is much better if it is smaller so that the Trajectory of the fly leg is not effected as much and is kept in the SLP that the rod gave it.

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Al.... I think he is correct, also. NOW: Do you think the momentum of the loop may be pulling the rod leg out as one shoots line ?

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Ally's PDF is incorrect since there is Tension in the loop. For an unrolling loop it has been proven that the point of maximum Tension in the top leg equals the Tension in the bottom leg and that in the case of the top leg the Tension is greatest at the loop front and tapers to zero at the fly. There is some disagreement as to whether loop morph is a result of Tension or aerodynamics, or to be more accurate which is most significant. Cheers, Paul

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If the tension is zero at the fly, then what pulls the fly in the direction of the cast ?

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Ally clarifies a point.....(He's included my answer to his original statement) :-

Firstly I made a typo in my message I wrote “running line” instead of “shooting head.

The shooting line the rod leg has velocity after line is released (shot) and that should be after the line loop has formed because by then we would have tension enough to pull out the running line and the heavy shooting head can indeed have sufficient kinetic energy to pull it a long way. If line is released during the period when the tension has disappeared immediately after the rod tip max velocity, either a poor or no line loop results - we have all seen this early release too often!

Ally.... I'll have to think a bit longer on your statement, "The loop does not pull the fly line forward, it holds it back....."

If I cut the fly line at its connection with the backing, the loop travels a long way forward and carries what is left of the rod leg of the line along with it. Either that, or the entire fly line / loop / fly leg & cut rod leg all function as a unit moving against atmospheric resistance. The fact that the loop doesn't unroll much in that situation, suggests that this is because the tension between the moving loop and the stationary rod tip has been eliminated.

I expected a reaction to that! If you cut the fly line connection to the backing the line will go pretty well until the line leaves the rod. After that it will bunch up because there is no restraint. Try using a shooting head with only 10 ft of running line and see what happens. I predict that the loop will form and as soon as the resistance from the rod end has gone the line will go haywire. Make sure that you cast in a safe direction!

When the rod tip and line reach max velocity the rod ducks into counterflex taking some line with it. The rest of the line (virtually all of the line) contains all the energy now, the rod is idle holding one end of the line. Line moving forward continues to fold back to the rod and stop (or in the case of shooting line travel much more slowly than the fly leg) because it is being held totally or somewhat (shooting line situation). Incidentally if you try to use a running line that is much to light for the shooting head you will find it very difficult to assure turnover, a halfway house to cutting the line.

Best wishes,

Ally Gowans

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Gordy,
How do counterflex abd rebound figure into this? I recall watching Paul Arden demonstrate distance casting at the instructors' seminar in Mt. Home and he appeared to have a rather wide loop on his back cast and then there was a tremendous counterflex and the loop suddenly went very small and straight back.
Jim

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Jim... A great deal of counterflex can appear to open up the loop.... but it actually looks, to me, that it dips the rod leg down. After that, rebound pulls some of the line back up behind that which was drawn down as the traveling loop appears to straighten the tip produced by the counterflex. I think that is what Paul meant when he referred to this dip being, "sucked back up".

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The evening's closing statement from Jim Valle:

For those of you who have never worked with Ally, Ally has a great approach to casting and especially Spey . He likes things simple, ergonomic, organized and under tension.(Organized means no slack to Ally’s spey casting, you will understand if you watch his spey video).

The most important part of discussions like this is” understanding”, every Master must be able to sit down with the most persistent and inquisitive student or CI and explain/draw loop formation and understand the line tension dynamics. And you can’t falter it must be in your mind ready to go…no hesitation …! And from more than one point of view…remember the artist and the engineers?

I have drawn this on paper, on the ground with rod and fly line or wherever the point comes that the particular student needs this information right now, if you put the student off you risk losing the opportunity to get this point across when the student is never going to be as ready as his mind is at that very moment.

Now you are going to see some different opinions here as we get into the very fine details. So keep at it till you “understand” all the vantage points.

There is no right or wrong , necessarily…look for similarities not differences. The truth is in the similarities!

Rod tip continues forward to its maximum extension, (tip is decelerating)…The LOOP is Born!

(we feel a release of tension (actually power or stroke) because we have stopped the rod) and the rod is doing its thing…

Rod tip goes into counterflex… but in my opinion there is still tension between the rod tip and the line (let’s leave shooting line out for now)

(I would also propose my own theory relative to various loop shapes as the result of throwing counterflex in the direction of the cast by stopping earlier…)

If you really want to see all this find a spey video and play it in slow motion, everything is magnified with longer rods and lines.

Now, you could agree with a bit of tension release during rebound and there I could understand Paul’s “sucking it up” however I see this like Hovering a fly a bit of tension in the opposite direction.

I think our ability to shoot line proves the rod leg is under tension with the rod tip, I think I am agreeing with most of what is discussed here just can’t understand a point of no tension, I can agree with the loop pulling some of the “counterflex dip” out of the line, the fly line has velocity true, the rod leg has velocity if you let it go, the rod leg has tension if you hold it. (then there is that friction in the guides)

Now that’s an engineer’s description, anyone want to explain this to an artist?