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Excellent FP on modeling

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Paul Arden
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Re: Excellent FP on modeling

#31

Post by Paul Arden » Sat Jul 20, 2019 9:20 am

Interesting conversation, guys.

Many years ago I remember seeing casting simulations on the Internet. I can’t remember all the parameters but I remember them being fairly basic. Are these still available?

Thanks, Paul
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Graeme H
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Re: Excellent FP on modeling

#32

Post by Graeme H » Sat Jul 20, 2019 10:03 am

Merlin wrote:
Sat Jul 20, 2019 8:21 am
Graeme gave an explanation for the down up motion of the loop nose in his video, but this is an interpretation, not a demonstration. Better than nothing maybe, for sure this refers to reality and not modeling and frankly speaking, we have no mean to check that with a model today, even not the beginning of an explanation with a scheme showing acting forces.

Merlin
Hi Merlin,

I think there is already a well established model for this behaviour of the line. If we aim a cast up, the loop goes up. James has modelled it in excel and mentioned it on the FP linked at the start of this thread.

I can repeat this particular experiment as often as you like.

Cheers,
Graeme
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Paul Arden
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Re: Excellent FP on modeling

#33

Post by Paul Arden » Sat Jul 20, 2019 10:51 am

So isolating inertia from aerodynamic lift is going to be a challenge. But just because inertia is responsible for lift (or keeping the fly leg level or nearly so) doesn't mean that aerodynamic lift does not also exist.

Cheers, Paul
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Merlin
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Re: Excellent FP on modeling

#34

Post by Merlin » Sat Jul 20, 2019 11:01 am

Graeme

I think you speak of a ball throw model here. I have the same and it does not prove anything regarding to a (complex) line flight.

Merlin
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Graeme H
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Re: Excellent FP on modeling

#35

Post by Graeme H » Sat Jul 20, 2019 11:20 am

Or maybe fly line is not so complex …

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Paul Arden
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Re: Excellent FP on modeling

#36

Post by Paul Arden » Sat Jul 20, 2019 11:42 am

James also mentioned that the real flight of ball is far more complex! And the flight of a fly line is most certainly more complex that that. I find it very interesting that many arguments in the physics forum become so polarised. This is a good example. Just because the fly line on the backcast can have a trajectory that lifts the front to the loop, doesn't mean that drag doesn't do the same. In order to understand if drag can cause the loop to lift, or oppose gravity, then we have to find a way of eliminating the other potential causes.

It was the same with the unrolling loop. It was either momentum only or an acceleration from the shortening of the fly leg (/momentum change at the loop). It turns out that it's a bit of both. The fly leg has momentum, but also it can also accelerate. Having argued about it for so many years I'm rather surprised that its discovery/proof hasn't led to further investigation. It opens up a whole chapter in trying to understand line tapers for example.

I think that this could be another one of those. Personally I think and DOG is much less significant than relative line angles but what I don't know is if DOG is significant in itself? I think that's really what we are trying to find out. :pirate:

Cheers, Paul
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Merlin
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Re: Excellent FP on modeling

#37

Post by Merlin » Sat Jul 20, 2019 11:48 am

Good point Paul. It could be that line taper has its say as well.

Merlin
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Walter
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Re: Excellent FP on modeling

#38

Post by Walter » Sat Jul 20, 2019 1:04 pm

Merlin wrote:
Sat Jul 20, 2019 8:21 am
I cannot clearly identify the models you mention and who runs them. I know a couple of models in the academic range: Gatti Bono and Wang.
Hi Merlin,

I guess it depends on whether you think Newton’s laws are a model, calculation, simulation or imagination for the description of objects in motion.
"There can be only one." - The Highlander. :pirate:

PS. I have a flying tank. Your argument is irrelevant.

PSS. How to generate a climbing loop through control of the casting stroke is left as a (considerable) exercise to the reader.

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Walter
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Re: Excellent FP on modeling

#39

Post by Walter » Sat Jul 20, 2019 1:21 pm

Paul Arden wrote:
Sat Jul 20, 2019 11:42 am

It was the same with the unrolling loop. It was either momentum only or an acceleration from the shortening of the fly leg (/momentum change at the loop).
Why is it momentum change at the loop? The fly leg has momentum and energy. Conservation of energy explains the acceleration. Losses due to air resistance explain why it doesn’t accelerate to infinity.
"There can be only one." - The Highlander. :pirate:

PS. I have a flying tank. Your argument is irrelevant.

PSS. How to generate a climbing loop through control of the casting stroke is left as a (considerable) exercise to the reader.

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Paul Arden
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Re: Excellent FP on modeling

#40

Post by Paul Arden » Sat Jul 20, 2019 1:36 pm

I don’t think it is momentum change at the loop; that’s just one way of calculating it. But you guys are the engineers and physicists, so you should be explaining it to me :pirate:

Cheers, Paul
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