Understanding Casting

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ohanzee

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To me, the tight-loop video (and gyro measurements) show the importance of loading (and unloading) the 'spring' of the rod. So, I don't think it is a 'myth', despite some of the comments above.

The 'spring' was conceived, or taken to mean stored energy that contributed to the speed or velocity of the cast, this led a lot of people up a dead end, it does minimally but is not the whole story, it's an over simplification and the whole story is more important in understanding what is going on.

The bend from leading the line to 'unloading' creates and defines the loop, there is a whole load of key things that happen in less than a second, all of them more useful than anything physically or line speed wise gained from stored energy.

First up I'd suggest is the compound effect of a bendy lever letting us efficiently impart energy longer, smoother and with less muscle.

We could focus on that and get somewhere but watch what happens when people start talking about and thinking in springs, it's a different set of physics principles.
 

James9118

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I found this graph fascinating. Showing how symmetrical the forward and back cast is with an expert caster and also how smooth the acceleration to a dead stop is.

View attachment 43815
What it shows to me is how completely out of your depth you are when it comes to physics. The chart shows angular velocity vs time. To get acceleration you need to take the derivative, dw/dt.
 

Tangled

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What it shows to me is how completely out of your depth you are when it comes to physics. The chart shows angular velocity vs time. To get acceleration you need to take the derivative, dw/dt.
Do you really need to be this unpleasant? This is just a hobby for most of us; have a bit of grace for god's sake man.
 

ohanzee

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Do you really need to be this unpleasant? This is just a hobby for most of us; have a bit of grace for god's sake man.

Would you prefer no one mentioned it? just keep pretending it's possible to understand things just by chatting about them?
 

Tangled

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Would you prefer no one mentioned it? just keep pretending it's possible to understand things just by chatting about them?
I actively want people to mention whatever they feel they need to mention, but to behave decently in the process. Surely we can be polite and non-confrontational? Is it really impossible for adults to discus a hobby without being obnoxious?
 

ohanzee

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I actively want people to mention whatever they feel they need to mention, but to behave decently in the process. Surely we can be polite and non-confrontational? Is it really impossible for adults to discus a hobby without being obnoxious?

I think you need to google Sexyloops board and read until you see how casting can be discussed thoughfully.

If we have learned anything here it is that you assuming control and not having the level of understanding needed to drive it, is a tiringly unproductive formula.
 

aenoon

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I actively want people to mention whatever they feel they need to mention, but to behave decently in the process. Surely we can be polite and non-confrontational? Is it really impossible for adults to discus a hobby without being obnoxious?
James was not being obnoxious, or unpleasant, he was saying it as it is, and politely telling you why you were wrong. Again.
 

andygrey

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To me, the tight-loop video (and gyro measurements) show the importance of loading (and unloading) the 'spring' of the rod. So, I don't think it is a 'myth', despite some of the comments above. It's also in accord with my own (limited) experience with a fly rod. But I'm not an expert caster, so maybe someone can post a video of them casting tight loops with a broomstick (or some other kind of rigid lever) to show us that they don't need the fly rod to flex.
The 'spring' was conceived, or taken to mean stored energy that contributed to the speed or velocity of the cast, this led a lot of people up a dead end, it does minimally but is not the whole story, it's an over simplification and the whole story is more important in understanding what is going on.

The bend from leading the line to 'unloading' creates and defines the loop, there is a whole load of key things that happen in less than a second, all of them more useful than anything physically or line speed wise gained from stored energy.

First up I'd suggest is the compound effect of a bendy lever letting us efficiently impart energy longer, smoother and with less muscle.

We could focus on that and get somewhere but watch what happens when people start talking about and thinking in springs, it's a different set of physics principles.
I think we are getting tangled in definitions here. If I understand @Grizzle Duster correctly he is using the term 'spring' to refer to the flex of the rod rather than energy storage.
 

ohanzee

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James was not being obnoxious, or unpleasant, he was saying it as it is, and politely telling you why you were wrong. Again.

I think so too, Tangled needs to adjust to the directness of a thing that is already understood by those contributing.
 

Rhithrogena

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The chart shows angular velocity vs time. To get acceleration you need to take the derivative, dw/dt.
Ahh, my failed A-level Physics comes back to haunt me!
Could you do a quick sketch of what a plot of acceleration vs. time might look like please James?
Ta!
 

ed_t

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Bead chain falling. Loop shape looks very familiar.

Mind numbing fact, the arrow on the left is a metal bead released at the same moment as one leg of the chain. The chain is accelerating faster than gravity.


View attachment 43798

The reason is conservation of energy

"This is because whenan object is suspended it has initial potential energy mgh . When it is dropped and2 reaches the bottom of its fall, it has zero potential energy and kinetic energy 12 mv. This energy must be conserved, however, and in the case of the chain, the mass of the moving section is constantly decreasing. To compensate and maintain the same energy, the velocity is higher than if the mass were constant, as in a free falling object."

(Been looking at whips, people have done more work on them than fly rods)

What you have there are 2 different systems with different dynamics and analysis. The single ball is the simplest with pe= mgh, ke=1/2mv^2, and simple determination of motion with the suvat equations.

The chain system has a dynamic and static leg. The dynamic leg has reducing mass but is gaining kinetic energy through the conservation of energy i.e. momentum by the static leg arresting the fall.

You should easily be able to understand this from understanding fly lines and tapers.

The chain example above is significantly different from a cast fly line in that there is a constant gravitational force adding energy to the dynamic leg in the direction of the loop. In a fly cast no more energy is added to the cast in the direction of the loop and gravity is dragging the system down to the ground.

If you drop a weight lifting dumbbell that has a slack chain fixed to one end and the place it is dropped from, initially it will stay horizontal. When the chain slack is taken up one end is constrained and the conservation of momentum transfers kinetic energy to the free end in addition to the kinetic energy due to gravity.

Nothing mind numbing unless it hits your head and nothing travelling faster than gravity.
 

Tangled

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Nothing mind numbing unless it hits your head and nothing travelling faster than gravity.
From the quoted paper

"One might expect that when the free end is dropped it will accelerate normally due to gravity.
According to Newton, all free falling objects accelerate at the same rate, which is known
to be 9.8 m/s . However, when this experiment is performed the free end reaches a point
where it is actually accelerating faster than this (fig. 1.2 and 1.3)."
 

Whinging pom

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Really I’m struggling to see why discussing the extra forces required to increase the fall rate of an object faster than gravity is helping to understand loop formation or trailing tendency’s . Sure gravity has some influence on the line without adequate propulsion, but is it really helpful to get bogged down here?
I wonder how many people on the forum did physics or maths to the levels you are taking this. I can follow what James and geenomad are saying .
But pe= mgh, ke=1/2mv^2,is beginning to feel like “ too much information” and just losing us!
Please guys remember who your audience is !
 

ed_t

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From the quoted paper

"One might expect that when the free end is dropped it will accelerate normally due to gravity.
According to Newton, all free falling objects accelerate at the same rate, which is known
to be 9.8 m/s . However, when this experiment is performed the free end reaches a point
where it is actually accelerating faster than this (fig. 1.2 and 1.3)."
Understanding fly lines, tapers and conservation of momentum. The free leg is being accelerated by gravity AND the conservation of momentum. No magic beans.
 

Tangled

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The free leg is being accelerated by gravity AND the conservation of momentum.
Ok, I guess you just misspoke when you said this then - "nothing travelling faster than gravity". No problem.
No magic beans.
No magic beans, the explanation was in the original post and the quoted paper.

And it's QI.
 

ohanzee

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I ate a whole packet of magic beans once, and did a magic fart, which made me disappear.

Anyone fancy a thread on casting?
 

LukeNZ

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From the quoted paper

"One might expect that when the free end is dropped it will accelerate normally due to gravity.
According to Newton, all free falling objects accelerate at the same rate, which is known
to be 9.8 m/s . However, when this experiment is performed the free end reaches a point
where it is actually accelerating faster than this (fig. 1.2 and 1.3)."
....and this improves your casting, and other beginning casters how?

It is a shame Newton was not a fly fisherman - but no doubt you would argue he was incorrect too.

What exactly is it you are hoping to hear...

Perhaps, your own view being acknowledged?
 
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