Welcome Dr William McGlinn

[Eagle Crest]

Bill,

Thanks for answering. I think the way to send documents to someone is to send a PM (private mail) to that person and they can provide an email address that you can send an attached file.

In your book, do you cover the mechanics of shooting line? My question is - where does the tension originate that can pull the slack fly line, between the reel and the stripping guide, through the rod guides and move it away from caster in t he direction of the loop?

Steve

[Walter]

Steve,

Have you tried this?

https://www.google.ca/?gws_rd=ssl#q=how ... rom+kindle

[grunde]

Steve: line tension (which is the force acting in line shoot) is given by the momentum change per unit time in the loop.

And as Walter said, just get the book on amazon, would be really surprised if line-tension is not discussedin it...

Grunde

[Walter]

The book has a very good discussion about tension and shooting line. I am finding it to he an enjoyable read. It is well organized and brings you through the physics of the cast starting with basic principles and adding to that in a logical sequence until a broad range of concepts have been covered. Its a bit like taking a series of first year physics tutorials using fly casting as the real world example.in each tutorial.

Thank you Dr. McGlinn for writing it.

[Eagle Crest]

Steve: line tension (which is the force acting in line shoot) is given by the momentum change per unit time in the loop.

Grunde - Please show your work, as they used to say in school. I understand that arm waving generality. I'm looking for it to be described in equations. I did that by modeling the loop dynamics with a cycloid parametric equations as a function of angular velocity, then differentiating with respect to time to get the velocity of each x and y components. I applied the Hamiltonian mechanics to show that as the motions transition from moving through the loop to stopped at the rod leg, the kinetic energy converts to potential energy and the potential energy according to Hooke's Law is tension in an elastic medium.

I'm looking for the detailed mathematical developments, as we see in Dr. McMillen's Dissertation. I'm sure others can get to the same place I did by other methods. I am curious how others are doing it in rigorous mathematical manner.

Steve

[grunde]

The solution is given bellow.

S is the line tension, mu is linear mass density, v_fl is the speed of the fly leg and v_rl is the speed of the rod leg.

No assumtion on loop shape or size. This is just Newtowns 2nd law.

[Walter]

Steve,

I'm glad you have purchased a copy of the dissertation. You should find most of your answers there.

[Walter]

Hi Dr. McGlinn,

I am enjoying your book very much. I especially like your approach of considering the goal of the cast to be to turn over the leader and fly and then working backwards from there.

I have a couple of questions relating to timing of various actions during the cast.

The first is about the haul - when should the haul end in relation to the casting stroke and what should the acceleration profile of the haul look like? In your book you talk about hauling early in the cast to provide early loading of the rod but if we finish the haul early then we are likely to get a tailing loop so we teach that the haul should start later in the cast to prevent this from happening. There has been some debate about whether the haul should end before the stop, at the same time as the stop or after the stop. What are your thoughts on this?

The next question is about coordinating the elbow thrust with rotation of the rod butt. There has been some debate about whether the elbow thrust adds anything to the cast. Your analysis shows that this would be a style thing, i.e. if not using elbow thrust then use a high back cast but if using elbow thrust use a level casting plane. In the case of using the elbow thrust what should the timing be for thrust vs rotation of the rod? Most of the distance casters that I know that use an elbow thrust feel that delaying rotation gives the highest line speed, i.e. do all of your translation early in the casting stroke and rotate at the end of the stroke. In figure 7.15, "Rod Response to 40 ft. cast action, with an elbow thrust of 120 cm", it appears that the elbow thrust and rotation happen in synch. Do you see any advantage for longer casts in delaying the rotation?

One final question, are you familiar with the 5 essentials of casting as taught by the Federation of Fly Fishers?

Thanks in advance.

Walter

[William McGinn]

Walter,
Concerning the haul: My analysis suggests that the loading done by the line has a larger effect on the final line speed then the speed of the line down the rod. That would seem to imply that the haul should be done early in the cast when the line lays out perpendicular to the rod. I have to think about the `tailing loop' question. The figure of the cast hauling early (Fig 8.7) doesn't seem to have a worse tailing loop then Fig3 7.10, 7.13, & 7.17 It might be interesting to compute the resulting cast if one hauls later in the cast.

Concerning the thrust question; I do model the thrust occurring in sync with the rod rotation - I think it just seems natural - and probably what I do - but I'm not a particularly good fly caster. But is it best that the thrust and rotation to sync. I don't know. There is only one natural unit of time associated with the cast - the natural half- period of the loaded rod . If not in sync I think the total time the two span shuld be the half-period. Again it might be interesting to compute with various overlaps .

I am not familiar with the 5 essentials of casting as taught by the Federation of Fly Fishers.

Bill

[Bernd Ziesche]

In your book you talk about hauling early in the cast to provide early loading of the rod but if we finish the haul early then we are likely to get a tailing loop so we teach that the haul should start later in the cast to prevent this from happening. There has been some debate about whether the haul should end before the stop, at the same time as the stop or after the stop. What are your thoughts on this?

My analysis suggests that the loading done by the line has a larger effect on the final line speed then the speed of the line down the rod. That would seem to imply that the haul should be done early in the cast when the line lays out perpendicular to the rod.

Hi Walter, hi Dr. McGlinn,
10 years ago I traveled to Austria, Switzerland and the Netherlands participating in fly casting lessons with some well respected fly casting instructors. My goal was to solve a tailing issue I had in my back cast when aerializing more than 20 meters of line length. None of the instructors could help me. In fact all three of them had exactly the same issue. Then I read about delaying the haul on the Sexyloops forum. I tried it and my tailing issue was gone, not only on 20 meters but on 25 meters of line length as well! Positioning the haul at the right time - at the very end of the stroke - in my experience is essential when aiming for a long line to be moved in a proper tight loop. The same holds true for positioning the main rotation ime. If I position the rotation early in the stroke I get nice relatively open loops compared to position it near the end of the stroke. I yet have to see a fly caster proving this not to hold true always.

About an early haul loading the rod... Achieving the same desired line speed - both for a hauled and a none hauled cast - I get more rod bend when casting without a haul.
Hauling means less rod bend unless we compare different desired line speeds.
Besides that rotating the rod in order to create most of the desired line speed means some rod bend. When I add the haul to that level of bend the haul ime does not add much (nearly none) rod bend.

I ran a small experiment:
I fixed my rod in a vertical position. Then I put some representative rod bend into it (tying nylon to the tip and tying the other end at a screw driver sticking it - under tension - into the grass). When I then added a haul - no matter how strong - nearly nothing happend to the rod bend.

Cheers
Bernd