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Contribution rod bend/spring makes to cast

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Paul Arden
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Contribution rod bend/spring makes to cast

#31

Post by Paul Arden »

If it's going to be measured I'll have to tune up first. I don't want Lasse's speeds to be higher than mine :p

I wonder if it's possible to llnk the video and the graphs together? I have a hard time visualising graphs and I know I'm not alone.

I don't have the skills to do that but someone here might?

What are you guys working on at the moment? Anything exciting?

Cheers, Paul
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Contribution rod bend/spring makes to cast

#32

Post by Merlin »

I think Gordy made such a link, the video versus the analysis.
I suggest to drop a mail to him.

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Contribution rod bend/spring makes to cast

#33

Post by Merlin »

A comparison of the components of line energy between a modern graphite tip action rod and a "parabolic" cane rod, without haul (fishing cast, average load):

graphite tip action: 20% elastic; 15% momentum; 65% leverage
cane parabolic: 25% elastic; 40% momentum; 35% leverage

Hauling can affect the share of momentum if it happens late (during rod unloading, it goes against momentum energy). Otherwise you can consider it affects the other components of line energy proportionnaly.

The share of elastic energy is higher for the cane rod because it is slower. Momentum effect is just amazing for that (tip heavy) rod.

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Contribution rod bend/spring makes to cast

#34

Post by sms »

Merlin, does the model allow to have the input from caster to be the same? What are the velocity differences between tip action graphite and butt action cane? Additionally, can you separate at what point and direction each component (spring, conservation of momentum and leverage) contribute to line velocity?
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Contribution rod bend/spring makes to cast

#35

Post by Merlin »

Hi Sakke

I can do that for exactly the same input. I will use a non hauled cast and compare these rods. The line kinetic energy can be split all along the cast I think, give me some time and I shall be back with figures.

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Contribution rod bend/spring makes to cast

#36

Post by Merlin »

Sakke

Here are the results. The input is exactly the same, and since these rods are not designed for the same line I used as a load the normalized weight (140 grains for the graphite rod and 160 grains for the cane rod).

Although the cane rod is shorter by half a foot, it gives an impressive speed because of its huge inertial effect. This effect involves an interaction with the spring one, which is not the case for the graphite rod.
graphite tip.JPG
graphite tip.JPG (45.28 KiB) Viewed 5143 times
Cane parabolic.JPG
Cane parabolic.JPG (43.08 KiB) Viewed 5143 times
Conclusion: the energy split is completely different. As usual, there is no universal rule.

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Contribution rod bend/spring makes to cast

#37

Post by Merlin »

A few information, the graphics are likely difficult to understand.

Using the same rotation history (input) for such rods is not expectable. In this example, one needs more than the double of energy to cast the cane rod.

If we change the input (casting arc) to get an equivalent speed by comparison to the graphite one, we still need 60% more energy for the cane rod taken in example.

The energy budget is very different, you have to spoil a significant amount of energy (because of its swing weight) with the cane rod (nearly half; it is less than 1/3 for the graphite rod).

So modern rods are mostly levers with a limited share of spring and momentum mechanisms in normal fishing conditions.

Merlin
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Contribution rod bend/spring makes to cast

#38

Post by Stoatstail50 »

So, just so I understand as a layman, what happens to tip velocities if the energy input is the same ?
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Contribution rod bend/spring makes to cast

#39

Post by Merlin »

In this condition, the tip velocity drops to 21.2 m/s for the cane rod, to be compared to 25.7 m/s for the graphite rod.

Not surprizing IMHO.

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Contribution rod bend/spring makes to cast

#40

Post by Stoatstail50 »

OK, thanks Daniel....I'm surprised it's that close to be honest.
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