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The practical side of considering loops as waves: Teaching and Self Improvement

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Dirk le Roux
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Re: The practical side of considering loops as waves: Teaching and Self Improvement

#141

Post by Dirk le Roux »

No, I don't have an example that contradicts that the wave travels away from the impulse (unless it has reflected at the tethers, of course). That is why I asked, and I might still have misread your statement, you to explain the wave propagation being determined by "the direction of tension in the line" instead of by the rod tip (the impulse).

I think I understand now that you meant more "along the tension" than "toward instead of away from the rod tip if tension (direction) so determines".

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Dirk
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Paul Arden
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Re: The practical side of considering loops as waves: Teaching and Self Improvement

#142

Post by Paul Arden »

Hi Graeme,
Since we are only moving one end of the string, the wave moves away from us through the medium once it's formed.
So because you always have the transverse wave propagating downwards with gravity this means that the impulse is always directed upwards in fly casting no matter what the loop plane?

Is this right?

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Paul Arden
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Re: The practical side of considering loops as waves: Teaching and Self Improvement

#143

Post by Paul Arden »

Well I have to say Merlin, that inverted loops are terrible fliers. Of course we are dealing with problems - the loop is generally cast closer to the ground and it’s impossible to have the efficiency of loop and rod planes being aligned. It would be interesting as an experiment to hang upside down from a bridge. The problem is my car keys might fall out my pocket or my feet pop out my boots.

It’s probably a task for Stuntman Ronan.

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Graeme H
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Re: The practical side of considering loops as waves: Teaching and Self Improvement

#144

Post by Graeme H »

Paul Arden wrote: Wed Oct 28, 2020 3:52 pm Hi Graeme,
Since we are only moving one end of the string, the wave moves away from us through the medium once it's formed.
So because you always have the transverse wave propagating downwards with gravity this means that the impulse is always directed upwards in fly casting no matter what the loop plane?

Is this right?

Cheers, Paul
Yep, but it's only a little upwards. Most of the impulse is directed horizontally in the same way that when we throw a cricket ball, we throw it mainly horizontally but also upwards to counter gravity.

The orientation of the loop's plane doesn't matter.

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Graeme
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Graeme H
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Re: The practical side of considering loops as waves: Teaching and Self Improvement

#145

Post by Graeme H »

Paul Arden wrote: Wed Oct 28, 2020 4:01 pm Well I have to say Merlin, that inverted loops are terrible fliers. Of course we are dealing with problems - the loop is generally cast closer to the ground and it’s impossible to have the efficiency of loop and rod planes being aligned. It would be interesting as an experiment to hang upside down from a bridge. The problem is my car keys might fall out my pocket or my feet pop out my boots.

It’s probably a task for Stuntman Ronan.

Cheers, Paul
There's another thing going on with upright vs inverted loops that makes the inverted ones more unpleasant and it's to do with the shape of the rod tip path.

The common rod tip path has a slight amount of convex movement (a "dome shape") which we naturally use to help us form a nice loop. At the beginning of the stroke, that tends to make the line go upwards a little, while at the end of the cast, it takes the tip away from the line path, opening the loop a bit.

Casting upside down, that dome is now a bowl and the line is thrown down at the start of the cast (aiding gravity) and opening the loop from the start. The whole stroke needs to change if we are going to cast with the tip always below the grip.

I can get an inverted loop working during a side cast because I can control the tip path at the start of the cast reasonably efficiently. I think I'd really struggle to make a nice inverted loop with the rod completely upside down throughout the cast.

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Graeme
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Paul Arden
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Re: The practical side of considering loops as waves: Teaching and Self Improvement

#146

Post by Paul Arden »

Yep, but it's only a little upwards. Most of the impulse is directed horizontally in the same way that when we throw a cricket ball, we throw it mainly horizontally but also upwards to counter gravity.
Hi Graeme,

I think it would help immensely if you drew some diagrams. 1) a vertical loop that is a transverse wave propagating downwards. 2) a side cast that is a transverse wave propagating downwards. If you can include impulse, tension, gravity and transverse wave propagation I think I would have a clearer picture!

Thanks dude,
Paul
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Graeme H
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Re: The practical side of considering loops as waves: Teaching and Self Improvement

#147

Post by Graeme H »

Sure, when I get home.

Both diagrams will be the same though.

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Re: The practical side of considering loops as waves: Teaching and Self Improvement

#148

Post by Torsten »

Graeme,
a) medium
What does that mean? It's a single word without context.
Any mechanical waves requires a "medium of transmission". For a string wave it's the string mounted between two pegs. But what's the medium if we assume the loop is a wave? If the fly line is the medium, we would accelerate move the entire medium around, doesn't make much sense to me.
(b) mechanical waves don't transfer matter (but energy, movement of mass is limited)
Are we covering this again? A mend transfers matter away from the direct line of sight between you and the fly.
I don't mean the mend but the loop in general. Waves don't transfer matter - but the loop transports the fly from me to the fish. Thus the loop can't be a wave. The mend is a different story, usually you don't want to move the fly and there I see a (limited) usefullness for the wave concept.
Wavelength is the inverse of frequency and is the spatial period. If the fly reaches the end of the forward cast every 2 seconds in a series of false casts, the frequency is 0.5 Hz and the wavelength is 2.
Well, no. As you have written the wavelength is the *spatial* period and therefore it can't be the inverse of the frequency. As the name says it's a length and you can compute it from the phase velocity divided by the frequency (the inverse of the frequency is just the period T).
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Graeme H
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Re: The practical side of considering loops as waves: Teaching and Self Improvement

#149

Post by Graeme H »

I've repeatedly answered these objections Torsten. It's getting ridiculous. You seem to want a special wave for a loop, so you go for it.

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Graeme
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Re: The practical side of considering loops as waves: Teaching and Self Improvement

#150

Post by Paul Arden »

Both diagrams will be the same though.
This is one reason why I need clarification because the impulse should be in different directions.

Cheers, Paul
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