George
If I consider a fishing cast (inspired by a record from one of Jason's casts) with a medium fast 905 type of rod (designed some 20 years ago), then We max, Def max, and MCL correspond to the same timing.
As usual with fly casting, there are many variables which can change the picture.
For Paul: and MAV is right on the vertical axis for this one!
Merlin
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What does the "hit" do?
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Re: What does the "hit" do?
Fly rods are like women, they won't play if they're maltreated
Charles Ritz, A Flyfisher's Life
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Re: What does the "hit" do?
Hi Merlin,
How do you work out We max? I’m sure that MCL was used because it was difficult to say exactly when We max occurred. It would be wonderful, if not too much trouble, to take a snap shot of each of those moments, since it’s far easier to conceptualise from the still image.
Interesting that Jason’s cast was at the vertical. I usually use the term perpendicular to describe what I’m thinking because trajectories can vary so much. Indeed it’s possible with some very short casts that the rod doesn’t reach the vertical.
I have a question from a long time ago, when I stood up a ladder with a small watering can attached to the rod tip. I moved the rod from straight down to almost straight up. (I remember being initially surprised by the tiny size of the watering can I needed to use. The first one was in danger of breaking the rod).
There was no bend in the rod straight down of course. I assume that straight down there is no load on the rod tip because the load is taken by my finger, however had the line had been knotted to the rod tip then the load would be one watering can (small).
It was fascinating to see the bend change throughout the 180 degrees angle.
The stored elastic energy must vary however. As does the effective length of the lever (and the effort at the rod butt).
So my question is, during normal casting, does the rod begin to unload (as a spring) the moment that load is reduced? The reason I ask, and I think it’s feasible, is if so then it means that we don’t have to initiate a stop or slowing sequence to start unloading but we can accomplish the same thing through angle change. (I think we are discussing SDM here!)
Furthermore, if this is possible, then any rod rotation would result in additional line speed because we would be rotating as the rod is unloading. This would completely eliminate the need for a stop.
Thanks, Paul
How do you work out We max? I’m sure that MCL was used because it was difficult to say exactly when We max occurred. It would be wonderful, if not too much trouble, to take a snap shot of each of those moments, since it’s far easier to conceptualise from the still image.
Interesting that Jason’s cast was at the vertical. I usually use the term perpendicular to describe what I’m thinking because trajectories can vary so much. Indeed it’s possible with some very short casts that the rod doesn’t reach the vertical.
I have a question from a long time ago, when I stood up a ladder with a small watering can attached to the rod tip. I moved the rod from straight down to almost straight up. (I remember being initially surprised by the tiny size of the watering can I needed to use. The first one was in danger of breaking the rod).
There was no bend in the rod straight down of course. I assume that straight down there is no load on the rod tip because the load is taken by my finger, however had the line had been knotted to the rod tip then the load would be one watering can (small).
It was fascinating to see the bend change throughout the 180 degrees angle.
The stored elastic energy must vary however. As does the effective length of the lever (and the effort at the rod butt).
So my question is, during normal casting, does the rod begin to unload (as a spring) the moment that load is reduced? The reason I ask, and I think it’s feasible, is if so then it means that we don’t have to initiate a stop or slowing sequence to start unloading but we can accomplish the same thing through angle change. (I think we are discussing SDM here!)
Furthermore, if this is possible, then any rod rotation would result in additional line speed because we would be rotating as the rod is unloading. This would completely eliminate the need for a stop.
Thanks, Paul
Re: What does the "hit" do?
We is calculated by the casting model, so it is easy for me to tell when maximum value occurs. It is of course nearly impossible from a video. Using a tracker may help you to locate MCL but for a competition cast, MCL does not correspond to rod maximum loading. Recording the coordinates of the tip top can make it as well.
I have another file where I can compute elastic energy depending on the pull angle on a rod; I call that “weight lifting”. I must have been inspired by some magic yesterday since I calculated parameters for a 906 HT type of rod and a 200 grams weight from -75 deg to +75 deg from horizontal position. The graphic below illustrates the results: In this graphic chord and deflection are in meters, elastic energies are in Joules. There is a maximum for elastic energy around 55 degrees above horizontal. You can see how elastic energy varies for each rod section, the one of the tip section increasing continuously (lines at the bottom).
Pay attention if you want to compare with a cast, the load is variable for a cast and not constant as it is in the case of the weight lifting exercise.
Rod unloading timing depends on rod speed/stiffness for a given input. In the table I posted before, you can see that We max for the 910 rod occurred 10 ms before We max for the 906 rod. Any rod will unload at some time which depends on the dynamic characteristics of the rod and line system (and of the input of course).
I see what you mean with SDM and no stop but it is practically impossible. First you have to stop the rod to avoid hitting the ground with the tip. Second SDM allows stopping the rod for a few ms but then the rod restarts rotating forward (I’m speaking about a forward cast, as usual). So anyway you have got to stop it, and it is easier thanks to SDM. The trick is then to match SDM “own stop” and the stop of caster’s rotation, and I guess it can be detected by torque at wrist level. In case of strong SDM (massive carry) SDM can even create a small pullback motion before restarting rotating the rod forward.
Merlin
I have another file where I can compute elastic energy depending on the pull angle on a rod; I call that “weight lifting”. I must have been inspired by some magic yesterday since I calculated parameters for a 906 HT type of rod and a 200 grams weight from -75 deg to +75 deg from horizontal position. The graphic below illustrates the results: In this graphic chord and deflection are in meters, elastic energies are in Joules. There is a maximum for elastic energy around 55 degrees above horizontal. You can see how elastic energy varies for each rod section, the one of the tip section increasing continuously (lines at the bottom).
Pay attention if you want to compare with a cast, the load is variable for a cast and not constant as it is in the case of the weight lifting exercise.
Rod unloading timing depends on rod speed/stiffness for a given input. In the table I posted before, you can see that We max for the 910 rod occurred 10 ms before We max for the 906 rod. Any rod will unload at some time which depends on the dynamic characteristics of the rod and line system (and of the input of course).
I see what you mean with SDM and no stop but it is practically impossible. First you have to stop the rod to avoid hitting the ground with the tip. Second SDM allows stopping the rod for a few ms but then the rod restarts rotating forward (I’m speaking about a forward cast, as usual). So anyway you have got to stop it, and it is easier thanks to SDM. The trick is then to match SDM “own stop” and the stop of caster’s rotation, and I guess it can be detected by torque at wrist level. In case of strong SDM (massive carry) SDM can even create a small pullback motion before restarting rotating the rod forward.
Merlin
Fly rods are like women, they won't play if they're maltreated
Charles Ritz, A Flyfisher's Life
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Re: What does the "hit" do?
Thanks Merlin. I’m just heading down the lake and will reply when I’m back properly. I wish I had Bruce’s casting machine!!
Cheers, Paul
Cheers, Paul
Re: What does the "hit" do?
Hi Merlin
All interesting stuff.
For a given blank, does the angle at which We max occurs vary with load?
I notice that if one compares the data from Paul’s 906 distance cast posted earlier in this thread to the graph above, particularly if the angles are corrected for line trajectory, then We max is occurring in a real cast with a similar rod at an angle much less than 55 degrees.
Thanks
George
All interesting stuff.
For a given blank, does the angle at which We max occurs vary with load?
I notice that if one compares the data from Paul’s 906 distance cast posted earlier in this thread to the graph above, particularly if the angles are corrected for line trajectory, then We max is occurring in a real cast with a similar rod at an angle much less than 55 degrees.
Thanks
George
Re: What does the "hit" do?
Hi George
You cannot compare a static situation (weight lifting) and a dynamic one (casting model), and derive conclusions about parameters like angles for some load (e.g.maximum elastic energy for the rod). Dynamic loads vary all along the cast and differ from static one (which is constant here). There is no reason to find comparable situations unless by chance.
For a cast the angle corresponding to We max varies with load for the same input, We max takes places earlier in the cast if the load is smaller, it can even take place before you reach maximum rotation speed.
Merlin
You cannot compare a static situation (weight lifting) and a dynamic one (casting model), and derive conclusions about parameters like angles for some load (e.g.maximum elastic energy for the rod). Dynamic loads vary all along the cast and differ from static one (which is constant here). There is no reason to find comparable situations unless by chance.
For a cast the angle corresponding to We max varies with load for the same input, We max takes places earlier in the cast if the load is smaller, it can even take place before you reach maximum rotation speed.
Merlin
Fly rods are like women, they won't play if they're maltreated
Charles Ritz, A Flyfisher's Life
Charles Ritz, A Flyfisher's Life
Re: What does the "hit" do?
Thank you, Merlin.