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Shooted cast

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Paul Arden
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Re: Shooted cast

#51

Post by Paul Arden » Sun Sep 06, 2020 4:35 pm

Hi Merlin,

Even allowing for overestimations are we comparing two distance casts here? I was told somewhere on this forum that on a full blown 5WT distance cast tip speed might reach close to 100mph and the haul was still an unknown. 10m/s is 22mph which I’ve always thought was low, which I think is why we measured mine to prove me wrong (again!) :)

It would be good to find a way to get some line speed numbers out of interest. Maybe we could suspend a rope tight between a few posts at tip path level, marked at regular intervals? For example that red and white striped safety tape might work? And then zebra mark the line. Perhaps there is something better we could attach to the line other than a flag?

Cheers, Paul
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Dirk le Roux
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Re: Shooted cast

#52

Post by Dirk le Roux » Sun Sep 06, 2020 6:00 pm

Interesting that with both of Lasse's two release timing casts, the max tip speed noticeably preceded RSP.

Inkedmax tip V - cast 1_LI.jpg

The red dots show the RSP tip positions. Magnitudes are greyed due to unknown fps on the file downloaded from Vimeo.

Inkedmax tip V - cast 2_LI.jpg

FWIW, my measurements of the events sequences:

Max haul speed was roughly halfway between MCL and RSP
Max tip speed occurred before RSP
Haul ended at RSP
Release on the delayed release cast (cast 1) was very shortly after RSP. Release on the earlier release cast was at RSP.

All the best,
Dirk

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Merlin
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Re: Shooted cast

#53

Post by Merlin » Sun Sep 06, 2020 6:30 pm

Hi Paul

Ideally we need a speed record but markers can slow things down. Any good pratical idea is welcomed. 100 mph seems to me rather low, but 160 mph may be an overstimate, who knows?

Merlin
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Re: Shooted cast

#54

Post by Merlin » Sun Sep 06, 2020 6:38 pm

Hi Dirk

You are right, this phenomenon has been known for years (I mentionned it in an earlier post), max line speed occurs slightly before RSP. This is valid for any cast simulation made with the 2D casting model. Your analysis is more accurate than mine and I fully agree with it. It is however a question of milliseconds, I do not think I saw something above 20 ms (competition cast). For Matthias' simulated cast I have 11 ms incidentally.

Merlin
Fly rods are like women, they won't play if they're maltreated
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Paul Arden
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Re: Shooted cast

#55

Post by Paul Arden » Mon Sep 07, 2020 12:54 pm

I don’t know, Merlin. For me short casts, while interesting, can have a very wide variation of inputs. What would be very interesting is to compare distance casts. For example to throw 50mph you don’t need to haul. Possibly you don’t even need the rod! (Although apparently you do). But if you are trying to optimise for distance it would be very interesting to see if the trend is the same. And if the timing is different how this impacts results.

Did Stefan get line speed measurements for their study? I’ll ask him! :)

Cheers, Paul
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Re: Shooted cast

#56

Post by gordonjudd » Mon Sep 07, 2020 4:00 pm

Max haul speed was roughly halfway between MCL and RSP
Dirk,
Did you compute the haul speed by taking the derivative of the distance between the stripper guide and the haul hand? That is the way to measure the effect that the haul has on line speed.

As pointed out by Grunde many years ago, the haul hand speed does not equal the line speed increase that comes from the haul.

Gordy

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Re: Shooted cast

#57

Post by gordonjudd » Mon Sep 07, 2020 4:43 pm

Magnitudes are greyed due to unknown fps on the file downloaded from Vimeo.
Dirk,
Those videos used a frame rate of 210 fps.
Gordy

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Re: Shooted cast

#58

Post by Paul Arden » Tue Sep 08, 2020 5:02 am

Very interesting. When we see the loop unroll on the 170 the loop point is close to the top. I had assumed that this was related to peak haul speed (there was a video of Lasse finishing his back haul around this point). However I can see now that it might be peak tip speed since that’s considerably before RSP.

Surely if the line speed at this stage in loop formation is higher then this will also help explain loop morph from round to top point?

Certainly when I look at the images above I can see a case for the haul peaking considerably pre RSP. (That’s another spanner in the works of everything I’ve been teaching the past 20 years :D).

I wish I had somewhere like where Lasse casts. I’ll have a bit of a butcher’s next time I’m in Grik.

Cheers, Paul
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Merlin
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Re: Shooted cast

#59

Post by Merlin » Tue Sep 08, 2020 8:37 am

Hi Paul

I checked the closest simulation I did of one of your competition cast and the delay betweeen max line speeed and RSP was 35 ms, much more than what I had in memory). Tip max speed took place 3 ms before max line speed.

Max line speed was 145 mph for the model. If you want a comparison the maximum "rigid rod speed" was 98 mph. Consider you can get 40% more thanks to the flexibility of the rod, and you are in the same ball park. Tip max speed was around 120mph so you end up with 25mph more thanks to the haul (max haul speed 28.6 mph). You got 87% of haul speed in the line, a good performance.

The sensibility of data to the input, both rod and line, makes things rather complicate. In that case there was an interest to haul "very" late, with some other simulations it can be different, you may better try to aim at a "not so late" haul. Not an easy task when the window for max haul speed is less than 80 ms.

Merlin
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Paul Arden
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Re: Shooted cast

#60

Post by Paul Arden » Tue Sep 08, 2020 10:58 am

I wonder if there is a way of digitising these without all the hard work? Maybe something like Graeme is doing. Because I would like to see 10 casts or more to see what the trends are.

I’m sure that we make those micro adjustments, after all that’s why we train.

I still think the haul speed is low. No one punches at 25 mph and we are using both hands plus rod rotation to stripping guide to haul. Might need a different camera angle as well. I’ll have a think.

Cheers, Paul
It's an exploration; bring a flyrod.

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