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Double Haul timing
Double Haul timing
It's not complicated at all if you have a duck with wheels on. I find making the one wrinkle easier than the accordion and I'm shite. How do you cause the up/down movement that makes a wave in every snap?
“Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius — and a lot of courage — to move in the opposite direction.” — Ernst F. Schumacher
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Paul Arden
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Double Haul timing
Are you asking about how wrinkles form? 
I’m not sure but I thought it was tied to line stiffness.
Cheers, Paul
I’m not sure but I thought it was tied to line stiffness. Cheers, Paul
Double Haul timing
Well Lasse,
First about "tension" - I'm choosing the Wiki's definition [1]:
[..] In physics, tension may be described as the pulling force transmitted axially
by the means of a string, cable, chain, or similar one-dimensional continuous object,
or by each end of a rod, truss member, or similar three-dimensional object; tension might
also be described as the *action-reaction pair of forces* acting at each end of said elements [..]
So tension requires a action-reaction pair of forces, and for the fly line (-> a string) it's a
scalar quantity expressed in the unit Newton [N].
Assume we have an ideal loop top and bottom leg are straight and parallel, the loop front is semicircular
and the loop height is very small compared to the overall line length. The line speed of the bottom leg
is = 0 (static). The top leg has defined momentum, kinetic energy, depending on top leg mass and top leg speed.
When the loop is unrolling, top leg gets shorter - but we know there is a law of Conservation of Energy -> energy
is constant -> line speed of the top leg will increase -> acceleration -> force -> tension.
For redirection of the line elements is a force required, because the amount of mass entering
the bottom leg and leaving the top leg is equal also the magnitude of the tension in top and bottom leg - measured
at the loop front - will be the same.
Note: the line tension decreases towards the line tip (because force is a product of mass *and* acceleration).
See Pauls post number #233, he is quite right.
A good source for this simple model is also Spolek's paper [2].
[..] In the absence of air drag, the fly can accelerate to increase its velocity by
an order of magnitude. Air friction dramatically decreases the effect, but some fly acceleration is
still predicted. [..]
--
Of course if you're including gravity and air friction, tension along the line will be quite different.
It is very difficult to determine tension from video analysis and I'm wondering how you're able to do this.
Maybe it's possible by deriving it indirectly from the acceleration of line elements, given some knowledge of
line properties and air drag.
--
Something for Gordy:
You don't need a loop for throwing a fly at distance. The simplest example is the Sbirolino used here by some fishing for seatrout. (a casting weight used together a fixed spool reel where the fly is attached). Still there will be some tension between the casting weight and the fly, else it wouldn't be possible to carry the fly along.
However, for fly casting the added tension by the loop front helps line turnover and is thus an important part of the fly cast.
--
[1] Tension (physics), from Wikipedia, the free encyclopedia, https://en.wikipedia.org/wiki/Tension_(physics)
[2] SPOLEK, Graig A. The mechanics of flycasting: The flyline. American Journal of Physics, 1986, 54. Jg., Nr. 9, S. 832-836.
https://core.ac.uk/download/pdf/37776458.pdf
I'll try, because I think there are some understanding problems.Now please explain how that is wrong, I'd love to learn!
First about "tension" - I'm choosing the Wiki's definition [1]:
[..] In physics, tension may be described as the pulling force transmitted axially
by the means of a string, cable, chain, or similar one-dimensional continuous object,
or by each end of a rod, truss member, or similar three-dimensional object; tension might
also be described as the *action-reaction pair of forces* acting at each end of said elements [..]
So tension requires a action-reaction pair of forces, and for the fly line (-> a string) it's a
scalar quantity expressed in the unit Newton [N].
Assume we have an ideal loop top and bottom leg are straight and parallel, the loop front is semicircular
and the loop height is very small compared to the overall line length. The line speed of the bottom leg
is = 0 (static). The top leg has defined momentum, kinetic energy, depending on top leg mass and top leg speed.
When the loop is unrolling, top leg gets shorter - but we know there is a law of Conservation of Energy -> energy
is constant -> line speed of the top leg will increase -> acceleration -> force -> tension.
For redirection of the line elements is a force required, because the amount of mass entering
the bottom leg and leaving the top leg is equal also the magnitude of the tension in top and bottom leg - measured
at the loop front - will be the same.
Note: the line tension decreases towards the line tip (because force is a product of mass *and* acceleration).
See Pauls post number #233, he is quite right.
A good source for this simple model is also Spolek's paper [2].
[..] In the absence of air drag, the fly can accelerate to increase its velocity by
an order of magnitude. Air friction dramatically decreases the effect, but some fly acceleration is
still predicted. [..]
--
Of course if you're including gravity and air friction, tension along the line will be quite different.
It is very difficult to determine tension from video analysis and I'm wondering how you're able to do this.
Maybe it's possible by deriving it indirectly from the acceleration of line elements, given some knowledge of
line properties and air drag.
--
Something for Gordy:
You don't need a loop for throwing a fly at distance. The simplest example is the Sbirolino used here by some fishing for seatrout. (a casting weight used together a fixed spool reel where the fly is attached). Still there will be some tension between the casting weight and the fly, else it wouldn't be possible to carry the fly along.
However, for fly casting the added tension by the loop front helps line turnover and is thus an important part of the fly cast.
--
[1] Tension (physics), from Wikipedia, the free encyclopedia, https://en.wikipedia.org/wiki/Tension_(physics)
[2] SPOLEK, Graig A. The mechanics of flycasting: The flyline. American Journal of Physics, 1986, 54. Jg., Nr. 9, S. 832-836.
https://core.ac.uk/download/pdf/37776458.pdf
Double Haul timing
Wrinkles form because of age and temperature PaulPaul Arden wrote:Are you asking about how wrinkles form?
Torsten
Please could you expand on this
Are you talking about a defined momentum from before loop formation or as a result of the loop ?top leg has defined momentum, kinetic energy, depending on top leg mass and top leg speed.
Regards
Vince
“Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius — and a lot of courage — to move in the opposite direction.” — Ernst F. Schumacher
https://www.sexyloops.com/index.php/ps/ ... f-coaching
https://www.sexyloops.com/index.php/ps/ ... f-coaching
Double Haul timing
Torsten,
A prediction from that model is that the fly leg will be accelerated up to fantastic speeds, and you're going to tell me that it doesn't happen because of drag.
Yet, the tension in the rod-leg is evident for all to see, it lifts the line off the ground in a 170 type cast. Yet I see no equivalent acceleration (although I do see some) on the free end, i.e. the fly-leg. Why is that?
A prediction from that model is that the fly leg will be accelerated up to fantastic speeds, and you're going to tell me that it doesn't happen because of drag.
Yet, the tension in the rod-leg is evident for all to see, it lifts the line off the ground in a 170 type cast. Yet I see no equivalent acceleration (although I do see some) on the free end, i.e. the fly-leg. Why is that?
Double Haul timing
Hi James
I see your point, the Spolek drag model is very crude. It is interesting that "Physical and Numerical Modeling of the Dynamic Behavior of a Fly Line Caroline Gatti and N. C. Perkins Department of Mechanical Engineering, University of Michigan" has many more refinements than the Spolek model and comes to the opposite conclusion, the fly decelerates throughout the cast. To be fair, it is a particularly shite casting stroke, I would be proud of it and could reproduce it. To get the same result as Spolek I think I would need to really pull back on the fly leg.
Regards
Vince
I see your point, the Spolek drag model is very crude. It is interesting that "Physical and Numerical Modeling of the Dynamic Behavior of a Fly Line Caroline Gatti and N. C. Perkins Department of Mechanical Engineering, University of Michigan" has many more refinements than the Spolek model and comes to the opposite conclusion, the fly decelerates throughout the cast. To be fair, it is a particularly shite casting stroke, I would be proud of it and could reproduce it. To get the same result as Spolek I think I would need to really pull back on the fly leg.
Regards
Vince
“Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius — and a lot of courage — to move in the opposite direction.” — Ernst F. Schumacher
https://www.sexyloops.com/index.php/ps/ ... f-coaching
https://www.sexyloops.com/index.php/ps/ ... f-coaching
Double Haul timing
Vince:
James:
It's still possible to show the acceleration by increasing the differential speed, this means pulling the bottom leg backwards (like it's done for the snap cast). Gordy's nice video clip shows it: https://vimeo.com/204562949
Even then, with the absence of air friction more complex models such as [1] (nonlinear FEM) show the acceleration of the fly too.
--
[1] Wang, Gang, and Norman Wereley. "Analysis of fly fishing rod casting dynamics." Shock and Vibration 18.6 (2011): 839-855.
The simplistic model starts usually with a full length top leg, a semicircular front, and a zero length bottom leg - it is assumed that the energy transfer rod - line was finished.Are you talking about a defined momentum from before loop formation or as a result of the loop ?
James:
I don't know if that's a statement or a question - but I'll comment. As shown by Spolek, air friction has a very significant impact on the acceleration, that's maybe why you can't see such a high increase in the video analysis.A prediction from that model is that the fly leg will be accelerated up to fantastic speeds, and you're going to tell me that it doesn't happen because of drag.
It's still possible to show the acceleration by increasing the differential speed, this means pulling the bottom leg backwards (like it's done for the snap cast). Gordy's nice video clip shows it: https://vimeo.com/204562949
See above comment; in my opinion air friction.Yet I see no equivalent acceleration (although I do see some) on the free end, i.e. the fly-leg. Why is that?
I'm failing to see the point, because in Spolek's paper you can see the much lower acceleration due to the air friction (see Fig. 5). You don't need always very sophistical models to show some points.I see your point, the Spolek drag model is very crude.
Even then, with the absence of air friction more complex models such as [1] (nonlinear FEM) show the acceleration of the fly too.
--
[1] Wang, Gang, and Norman Wereley. "Analysis of fly fishing rod casting dynamics." Shock and Vibration 18.6 (2011): 839-855.
Double Haul timing
Torsten
Vince
My reading of the Spolek model is a decelerating fly leg all the way through the casting stroke and it has a square front for the aerodynamic calculation. If I look at the DT and Level line predictions, I can’t reproduce the square front but that casting stroke velocity profile, even if it was physically possible would not result in a nice turned over cast. I would suggest that the assumptions have taken it so far away from the real world that it is not representative?The simplistic model starts usually with a full length top leg, a semicircular front, and a zero length bottom leg - it is assumed that the energy transfer rod - line was finished.
If I start a cast with such a low velocity and then overestimate the value of drag then I could overestate the effect of drag on a cast. The Gatti Bono paper I referenced corrects that overstatement and has no acceleration.I'm failing to see the point, because in Spolek's paper you can see the much lower acceleration due to the air friction (see Fig. 5).
Vince
“Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius — and a lot of courage — to move in the opposite direction.” — Ernst F. Schumacher
https://www.sexyloops.com/index.php/ps/ ... f-coaching
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Double Haul timing
I'll put this in print here, the Spolek paper is, in my opinion, very seriously flawed.
Torsten - in my front page on Thursday I wrote about observing 'loops' within a vacuum environment - if you didn't read it I stated that I don't see them accelerate - why is that?
Also, the Spolek paper totally ignores the work done by the fly-leg on the rod-leg - it lifts it a couple of metres of the ground in the case of a 170 cast - does that lift happen by magic?
The paper simply doesn't match the reality of what's happening, and just chucks in drag to cover it's inadequacies. Either we accept it's flawed or we have to start disbelieving our own eyes.
James
Torsten - in my front page on Thursday I wrote about observing 'loops' within a vacuum environment - if you didn't read it I stated that I don't see them accelerate - why is that?
Also, the Spolek paper totally ignores the work done by the fly-leg on the rod-leg - it lifts it a couple of metres of the ground in the case of a 170 cast - does that lift happen by magic?
The paper simply doesn't match the reality of what's happening, and just chucks in drag to cover it's inadequacies. Either we accept it's flawed or we have to start disbelieving our own eyes.
James
Double Haul timing
James,
Present me a data of a true fly cast in vacuum and we'll see.
Well, what should I write? Your article does not convince me.Torsten - in my front page on Thursday I wrote about observing 'loops' within a vacuum environment - if you didn't read it I stated that I don't see them accelerate - why is that?
Present me a data of a true fly cast in vacuum and we'll see.
Really, this wasn't the goal of the paper.Also, the Spolek paper totally ignores the work done by the fly-leg on the rod-leg - it lifts it a couple of metres of the ground in the case of a 170 cast - does that lift happen by magic?