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Analysing loop propagation

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Merlin
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Re: Analysing loop propagation

#31

Post by Merlin » Tue Sep 22, 2020 12:18 pm

Graeme

Many thanks in advance to give an answser to my post #21 about a vertical snap cast from the balcony, the line being vertical at start. Would you then consider it is a tranverse wave travelling along and horizontal (long virtual) line?

Merlin
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Graeme H
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Re: Analysing loop propagation

#32

Post by Graeme H » Tue Sep 22, 2020 12:21 pm

Perhaps you can answer my question before we go further, eh? (Which rod action is no longer a wave?)
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Graeme H
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Re: Analysing loop propagation

#33

Post by Graeme H » Tue Sep 22, 2020 12:30 pm

Merlin wrote:
Tue Sep 22, 2020 12:18 pm
Graeme

Many thanks in advance to give an answser to my post #21 about a vertical snap cast from the balcony, the line being vertical at start. Would you then consider it is a tranverse wave travelling along and horizontal (long virtual) line?

Merlin
So if you mean I raise the rod tip and lower it quickly to make a snap cast, does the wave move horizontally like the wave travels along this rope?





Yes, I'd say it does. So, after you have answered my question (I asked first!), what's your point?
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Paul Arden
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Re: Analysing loop propagation

#34

Post by Paul Arden » Tue Sep 22, 2020 1:18 pm

Hi Graeme,

I think quite a few people are happy to consider it a wave :p

But transverse wave doesn’t make sense to me either. Here is a definition of transverse wave
transverse wave

a wave in which the medium vibrates at right angles to the direction of its propagation.
The loop wave is not at right angles to propagation but aligned in the same direction.

Cheers, Paul
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gordonjudd
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Re: Analysing loop propagation

#35

Post by gordonjudd » Tue Sep 22, 2020 3:44 pm

when it's really only falling at a similar rate to the upward propagation of the wave
Graeme,
The problem with that argument is that initial +y velocity of the loop's launch will result in a linear increase in its height while gravity will produce a quadratic decrease.

Thus just as with cannon balls, the negative increase in the y velocity related to gravity will soon overtake the initial constant +y velocity of the loop's launch and cause the object to fall.

For the loop to maintain its height or rise there must be an upward force that is equal to the downward mg force of gravity.

Gordy

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Merlin
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Re: Analysing loop propagation

#36

Post by Merlin » Tue Sep 22, 2020 6:11 pm

So this looks like a snap cast.
Rope.JPG
Rope.JPG (42.5 KiB) Viewed 138 times
I agree with Paul, so would you find the compromise of saying that a loop is a "wave" be acceptable Graeme?

No argument will ever convince you that the loop is not a "transverse" wave.

Merlin
Fly rods are like women, they won't play if they're maltreated
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Graeme H
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Re: Analysing loop propagation

#37

Post by Graeme H » Tue Sep 22, 2020 8:45 pm

Apparently none of you want to answer the question I posed in post #19. That's sad.
Paul wrote:But transverse wave doesn’t make sense to me either. Here is a definition of transverse wave
transverse wave

a wave in which the medium vibrates at right angles to the direction of its propagation.
That's exactly what I've been saying. That none of you want to consider direction of propagation to be vertical still has me perplexed even when I post a video of it happening.

What's the point of starting a thread called "Analysing loop propagation" if nobody actually wants to question their underlying assumptions? This is not analysis: this is just confirmation of old ideas.
Paul wrote:I think quite a few people are happy to consider it a wave :p
Perhaps that's true, as long as they can make up a name for it that does not exist outside Sexyloops.

From here:
There are two types of mechanical waves:
  • Longitudinal waves – In this type of wave, the movement of the particle are parallel to the motion of the energy i.e. the displacement of the medium is in the same direction to which the wave is moving. Example – Sound Waves, Pressure Waves.
  • Transverse waves – When the movement of the particles is at right angles or perpendicular to the motion of the energy, then this type of wave is known as Transverse wave.
So, according to people here, since the loop is not a transverse wave, it's a longitudinal wave, right? I call that one BS. (I think everyone agrees it's not a longitudinal wave.)

In fact, very few of the long-time protagonists in this debate are "happy to call the loop a wave". I don't know what they want to call it, but they are so fixated on the fact that the medium is displaced at the end of the cast that it overpowers their consideration of the remaining features of a transverse wave.

For me, every bend that travels long the fly line is a transverse wave. I don't care if it's a tiny one from rod counter flex or a huge one from making a cast; the travelling bend is a wave. The question then becomes "what is the direction of propagation for that wave?" The answer to that lies in the definition you found Paul:
a wave in which the medium vibrates at right angles to the direction of its propagation.
The medium is vibrating horizontally and a right angle to that is the vertical.

Cheers,
Graeme
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Graeme H
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Re: Analysing loop propagation

#38

Post by Graeme H » Tue Sep 22, 2020 8:49 pm

Merlin wrote:
Tue Sep 22, 2020 6:11 pm
I agree with Paul, so would you find the compromise of saying that a loop is a "wave" be acceptable Graeme?

No argument will ever convince you that the loop is not a "transverse" wave.

Merlin
What sort of mechanical wave do you want it to be Merlin? Longitudinal or transverse?

Or are we going to follow Sexyloops tradition and make up something new that only applies to the physics of casting?

(And you STILL haven't answered my question from post #19, have you? Typical. :glare: )

Cheers,
Graeme
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Graeme H
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Re: Analysing loop propagation

#39

Post by Graeme H » Tue Sep 22, 2020 8:54 pm

gordonjudd wrote:
Tue Sep 22, 2020 3:44 pm
when it's really only falling at a similar rate to the upward propagation of the wave
Graeme,
The problem with that argument is that initial +y velocity of the loop's launch will result in a linear increase in its height while gravity will produce a quadratic decrease.
The problem with this argument is that we are talking about a wave travelling through a falling medium in which the tension is variable and therefore the wave velocity is not constant.

Cheers,
Graeme
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Paul Arden
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Re: Analysing loop propagation

#40

Post by Paul Arden » Tue Sep 22, 2020 10:21 pm

So in a flu cast the wave is travelling upwards?
I have to spend some time thinking about that. I think I may be shifting more towards James’ view :D

Back later.

Cheers, Paul
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