Understanding Casting

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ohanzee

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How can we fix it if we don't know how it happens?

We remove the cause, which we can identify in relation to the symptom, Paul's single post is all anyone needs to know to self analyse, find and fix.

When you go to the doctor with a broken leg you want to know how to fix it, not how bones grow.
 

James9118

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So I'm wondering how that short dip manages to pass over the other leg of the line twice, when the gap between the legs is measured in feet. Has the subtle wave been amplified?
The subtle dip in the rod tip gives a portion of the line some momentum in a transverse direction to the direction of the cast. That bit of line continues to move in that direction, so the dip in the fly line (the tail or tailing tendency) grows in amplitude as the cast progresses. Therefore the amplitude of what you see as the casting fault in no way reflects the size of the deviation of the rod tip.

James
 

Tangled

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The subtle dip in the rod tip gives a portion of the line some momentum in a transverse direction to the direction of the cast.

Agreed, and the direction of the wave is up and down.

That bit of line continues to move in that direction, so the dip in the fly line (the tail or tailing tendency) grows in amplitude as the cast progresses.

Somehow, energy needs to enter that small section of the line containing the wave and amplify it. But how can that happen, all the energy in the wave form is now not in the transverse direction? Wouldn't you expect the dip to progress along the line and if anything reduce in size as it loses energy?

Therefore the amplitude of what you see as the casting fault in no way reflects the size of the deviation of the rod tip

Ok, that is the assertion, can we show it happening?
 

Tangled

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We remove the cause, which we can identify in relation to the symptom
Is the symptom a closed loop or an tailed loop?

When you go to the doctor with a broken leg you want to know how to fix it, not how bones grow.

Doctors know how to fix a broken leg because they understand the precise nature of the break, the precise method necessary to fix it and the way the bone grows to mend it.

If you're not interested in the why as well as the how, please just stick to your COVID and politics thread, you're not keeping up here..
 
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James9118

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Somehow, energy needs to enter that small section of the line containing the wave and amplify it.


Ok, that is the assertion, can we show it happening?
No energy is required - unfortunately this is where the wave analogy effectively breaks down and you end up with good old Newtonian physics - an object stays in motion unless a force acts etc., etc.

So that portion of the line, the tail, has some momentum that isn't in the direction of the main cast. It will continue to move in that direction unless some force acts to prevent it doing so. Therefore the dip in the fly line (or amplitude if you want to go back to the wave analogy) will continue to grow in the absence of forces.

How can we show it - easy just film some tails and watch it back in slow motion.

James.
 

Tangled

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No energy is required unfortunately this is where the wave analogy effectively breaks down and you end up with good old Newtonian physics - an object stays in motion unless a force acts etc., etc.

Energy is always required! :) I'm struggling to see how the energy that created the transverse wave gets amplified as it moves away from the rod tip. There are forces woking against further growth, gravity and friction of course but also the wave moving the line forward is pulling on the line in the forward direction presumably flattening it?

So that portion of the line, the tail, has some momentum that isn't in the direction of the main cast.

Doesn't it only have the momentum imparted by the weak up and down motion of the rod tip and isn't all of that momentum shown in the size of the initial wave? How does the wave we describe as subtle become big enough to grow beyond the width of the entire loop?

How can we show it - easy just film some tails and watch it back in slow motion.

Got any that shows the transverse growing as it moves down the line? That would be fascinating.
 

James9118

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Energy is always required
And that's me out. Look up Newton's first law of motion. Read posts #342 & #345 again and you'll see the answers to your questions in post #349.

Please explain your 'forces working against further growth' comment. i.e. explain how you think gravity, working in the same direction in which the line in the tail is propagating, somehow opposes the growth?

James
 

Tangled

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And that's me out.
That would be a shame.

Look up Newton's first law of motion.
I'm aware of all Newton's laws.

Read posts #342 & #345 again and you'll see the answers to your questions in post #349.

I have read them. Can you explain the point you think I'm missing?

Please explain your 'forces working against further growth' comment. i.e. explain how you think gravity, working in the same direction in which the line in the tail is propagating, somehow opposes the growth?

I'll do my best.

The tailing loop wave is described as transverse but in simple terms we mean up and down as viewed from the side, while the major wave direction is predominantly in a direction away from the caster.

A wave moving up and down is of course fighting gravity in its upward direction and being accelerated in the downward direction. The net effect is neutral except for friction which works negatively in both directions.

But there is no obvious force amplifying the transverse wave that I can see. Where does it come from? Serious question; how does the subtle wave created by the angler get amplified once it's left the rod? We see the wave form, peak and decline.

Is there a slomo of the wave getting bigger? I'd love to see it. Empirical evidence trumps all this navel gazing.
 

ohanzee

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So that portion of the line, the tail, has some momentum that isn't in the direction of the main cast. It will continue to move in that direction unless some force acts to prevent it doing so.

I think this is very well explained and probably couldn't be put simpler.
 

ohanzee

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The tailing loop wave is described as transverse but in simple terms we mean up and down as viewed from the side, while the major wave direction is predominantly in a direction away from the caster.

A wave moving up and down is of course fighting gravity in its upward direction and being accelerated in the downward direction. The net effect is neutral except for friction which works negatively in both directions.

But there is no obvious force amplifying the transverse wave that I can see. Where does it come from? Serious question; how does the subtle wave created by the angler get amplified once it's left the rod? We see the wave form, peak and decline.

Is there a slomo of the wave getting bigger? I'd love to see it. Empirical evidence trumps all this navel gazing.

This is why James wins casting competitions and Tangled still doesn't understand how a loop works.
 

PaulD

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The problem here is a simple one to understand. James, I'm lead to believe, is a physicist of some renown, Tangled isn't.
 

Tangled

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Here's a pretty clear slomo video of something that looks very like what we call a tailing loop. It also shows a graph of how the power was applied during the cast.

We can see the shallow dip caused by the bending rod. You need to pause it every second or so to see what is happening as the cast propagates. What would you say is happening here?

 

andygrey

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Energy is always required! :) I'm struggling to see how the energy that created the transverse wave gets amplified as it moves away from the rod tip. There are forces woking against further growth, gravity and friction of course but also the wave moving the line forward is pulling on the line in the forward direction presumably flattening it?



Doesn't it only have the momentum imparted by the weak up and down motion of the rod tip and isn't all of that momentum shown in the size of the initial wave? How does the wave we describe as subtle become big enough to grow beyond the width of the entire loop?



Got any that shows the transverse growing as it moves down the line? That would be fascinating.
The energy is not amplified, it just continues to move in the same direction...
 
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