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Loop morph & water tension

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Paul Arden
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Loop morph & water tension

#1

Post by Paul Arden »



You might need to look at it in 4K to see the loop morph, and on a laptop. :p

I found the stability of this loop to be very interesting because it started from an on-the-water position. It makes me think that the anchor in Spey casting doesn’t just stabilise the D-loop but also might add additional tension to the loop while it unrolls, which is why you commonly see these loops in Spey casting but less so with overhead casting. Is that possible? Or is it that the water tension allows us to eliminate the Dangle? Ie the line is perfectly straight to the fly.

So my question is the “cleaner” loop shape a result of more tension in the fly leg or a result of a straighter fly leg?

Any ideas?

Cheers, Paul
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Re: Loop morph & water tension

#2

Post by gordonjudd »

So my question is the “cleaner” loop shape a result of more tension in the fly leg or a result of a straighter fly leg?
Paul,
I would add the impact of drag forces (especially form drag) to that list of factors that impact loop morph.

I would agree with Thorsten that:
The wedge shape is usually a result of loop morphing, such loop shapes begin with a roundish loop and morph into a pointy loop shape.
Major factors that promote in my opinion the change of shape are the trajectory of the line, tension and aerodynamic forces (especially the drag force). If the line speed is high enough even large rounder loops morph into this shape.
Gordy
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Re: Loop morph & water tension

#3

Post by Paul Arden »

Thanks Gordy. Hope you are well! I was really interested in the difference between two loops, one delivered from an anchor placement and the other from an aerielised position. I’m on my phone now but I’ll open up the laptop later and grab a few frames. I just remember thinking at the time that the loop had much more stability than I’m used to seeing and it reminded me of a Spey cast.

Cheers, Paul
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Re: Loop morph & water tension

#4

Post by Paul Arden »

OK I think there is something more interesting going on here and I would like to try to understand it.

"Tension Cast"
LOOP1.jpg
There is a bend put in the line due to tip path trajectory in relation to fly leg.
LOOP2.jpg
Which then becomes "wavy"
LOOP3.jpg
How does this part happen? The wavy part overtakes the fly leg in front.
LOOP4.jpg
And then how/why does it disappear?
LOOP5.jpg
Maybe it's not so stable after all :laugh:

Thanks, Paul
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Paul Arden
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Re: Loop morph & water tension

#5

Post by Paul Arden »

Is it an acceleration because of the wavy part reaching the front taper of the fly line perhaps?
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Dirk le Roux
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Re: Loop morph & water tension

#6

Post by Dirk le Roux »

Paul Arden wrote: Mon Sep 20, 2021 4:45 am OK I think there is something more interesting going on here and I would like to try to understand it.


Hi Paul

It's now off your original question but I have been puzzled by exactly that occurance, an initial bump morphing into an overtaking loop. I have very similar footage.

I believe it is exactly similar in dynamics to a dangle overtaking, just upside down. What causes the overtaking though? Form drag is an easy candidate at the latter stages where there is a significant frontal component, but the initial bump's form drag is not that situation at all.

There is more at play and I think the tendency for the very tail part's direction of travel to govern line travel and loop shape is a major player.

All the best,
Dirk
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Re: Loop morph & water tension

#7

Post by gordonjudd »

an initial bump morphing into an overtaking loop.
Dirk,
Could you point out where the initial bump occurs and then sequence of shapes where it morphs into an overtaking loop? What does it overtake?

Are you talking about the transverse wave that is propagating towards the fly end of the line or some other disturbance that overtakes the front loop?

Thanks for clarifying what you and Paul are seeing in that sequence.

Gordy
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Re: Loop morph & water tension

#8

Post by Lasse Karlsson »

Gordy, I think it's the end of the flyline, where the wave turns into a loop that overtakes the end of the line, not the leading edge loop. you can see it in the second last picture of Pauls.
My take is its slack getting jiggy with tension...

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Lasse
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Re: Loop morph & water tension

#9

Post by Dirk le Roux »

Hi Gordy
gordonjudd wrote: Sat Sep 25, 2021 2:02 pm Dirk,
Could you point out where the initial bump occurs and then sequence of shapes where it morphs into an overtaking loop? What does it overtake?
Here you go, Gordy

bump morph_1.jpg

The shape's traces are in yellow, showing the evolution from a quite subtle initial bump.

Best regards,
Dirk
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Re: Loop morph & water tension

#10

Post by Paul Arden »

Hi chaps,

I’m not even sure it was a bump as much as an angle change from tip path the original line position. I agree that it’s an inverted Dangle, Dirk. It’s fascinating that it then starts to overtake.

Cheers, Paul
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