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Necessary terms
- Stoatstail50
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Nope, the energy you input would go directly to moving the whole rod. The bending and unbending of the rod uses energy and so adds to the system loss.
Unless you are looking at relative efficiencies of one rod over another, I'm not sure that looking at the mechanics, from a purely energy perspective, for me anyway, is terribly useful.
Unless you are looking at relative efficiencies of one rod over another, I'm not sure that looking at the mechanics, from a purely energy perspective, for me anyway, is terribly useful.
Casting Definitions
Many men go fishing all of their lives without knowing that it is not fish they are after.
Many men go fishing all of their lives without knowing that it is not fish they are after.
- Stoatstail50
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I think so, but I dont know what to call it...
Lets call it Newtons Second Law perspective.
For linear forces, Force equals Mass times Acceleration, slightly different equation for angular forces but the same principle.
Angular or rotational force is called "Torque", Engineers might call it a "Turning Moment"
"Acceleration" is another necessary term I would include, that is the rate of change in Velocity.
To move the line from one position to another we have to change its velocity ie, we have to accelerate it.
We could just chuck the line with our hand, we can, obviously, but you dont get very high line velocities...so we use a rod as a lever to help increase the velocity of the line ?.
Lever, another necessary term.
The rod/lever serves to amplify the velocity of the tip over the velocity of a point near the butt. That is the tip travels further in the same time, and therefore faster, than a point near the butt. This isn't strictly speaking, "Mechanical Advantage" but it is an advantage nontheless.
The longer the rod/lever the bigger this advantage.
Lets call it Newtons Second Law perspective.
For linear forces, Force equals Mass times Acceleration, slightly different equation for angular forces but the same principle.
Angular or rotational force is called "Torque", Engineers might call it a "Turning Moment"
"Acceleration" is another necessary term I would include, that is the rate of change in Velocity.
To move the line from one position to another we have to change its velocity ie, we have to accelerate it.
We could just chuck the line with our hand, we can, obviously, but you dont get very high line velocities...so we use a rod as a lever to help increase the velocity of the line ?.
Lever, another necessary term.
The rod/lever serves to amplify the velocity of the tip over the velocity of a point near the butt. That is the tip travels further in the same time, and therefore faster, than a point near the butt. This isn't strictly speaking, "Mechanical Advantage" but it is an advantage nontheless.
The longer the rod/lever the bigger this advantage.
Casting Definitions
Many men go fishing all of their lives without knowing that it is not fish they are after.
Many men go fishing all of their lives without knowing that it is not fish they are after.
...where the fk are they ?... :
Somebody is asking for something?
Well, I thought one would have chosen "swing weight" instead of inertia, this is a common term in golf and quite illustrative also.
The story of elastic energy stored in the rod compared to the kinetic energy of the line has been discussed several times, but the last dispute on "torque" showed that some elastic energy is used to help decelerating the rod rotation, while the diminishing force of the unloading rod still gives some energy to the line as it is moved forward. It remains quite difficult to give numbers about that.
An order of magnitude: two thirds of caster's energy input goes into the line, one third remains in the rod. Values change along with rod speed versus casting style.
Maybe engineers should invent an exam to see if instructors do understand fly casting mechanics (ooops, another big provocation!) :p
Merlin
Fly rods are like women, they wont´play if they're maltreated.
Charles Ritz, A Flyfisher's Life
Charles Ritz, A Flyfisher's Life
- Marc LaMouche
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hi Merlin,Merlin wrote:Maybe engineers should invent an exam to see if instructors do understand fly casting mechanics (ooops, another big provocation!) :p
i like that idea and would support it for a master level certification. (and recertification)
given the available information we've had over the last several years and all the still rampant BS that's going around in certain levels of instruction, forums, shop talk and advertising, this could only be a good thing and yet another way to weed out those (professionals) who don't believe in continued education.
cheers,
marc
- Stoatstail50
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Not a provocation at all, I know several people who would sign up to that tomorrow....I would.Merlin wrote:Maybe engineers should invent an exam to see if instructors do understand fly casting mechanics (ooops, another big provocation!) :p
Merlin
What is at issue is how you are going to educate non-engineers to pass it. This involves explaining potentially complex concepts simply and accurately.
This is exactly what I would like.
Casting Definitions
Many men go fishing all of their lives without knowing that it is not fish they are after.
Many men go fishing all of their lives without knowing that it is not fish they are after.
- Marc LaMouche
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Stoatstail50 wrote:What is at issue is how you are going to educate non-engineers to pass it. This involves explaining potentially complex concepts simply and accurately.
not such a big issue, Mark. this thread's list actually goes a long way in doing just that. all it would need is a few 'real world' examples in an explain and demonstrate manner.
cheers,
marc
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not such a big issue, Mark. this thread's list actually goes a long way in doing just that. all it would need is a few 'real world' examples in an explain and demonstrate manner.
As we don't seem to agree as to the contribution of bend in this thread I would say we have a ways to go.
Tk
never complain, never explain
- Stoatstail50
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Tony
I think that it has been pretty well demonstrated that, depending on the type of cast, roughly 80% of line velocity is generated by the rod as a lever and roughly 20% by the rod as a spring.
This doesn't necessarily mean, however, that a bendy rod generates 20% more line velocity than a rigid one of the same length.
The spring element may be compensating for the loss of length during the period of the cast when the rod is used as a lever and its consequent reduction in tip velocity.
Its easy to demonstrate the beneficial effect of the spring if the rod is modelled to behave as a linear spring throughout the casting stroke. The rod, however, in my world anyway, only operates as a spring at the end of the casting stroke. If you don't model the negative effect of length reduction during the period of leverage then you run the risk of elevating the benefit of the spring effect to a position of importance that it might not merit.
Springs are modelled on the basis of Hookes Law. This just says basically that the spring extends in proportion to the load. In the argument in bendy rods it appears that the spring constant, which is something that describes the bendyness or elasticity of the spring, has been used as a true constant, a linear value, but my rods, like yours, are tapered so the spring constant is variable, non-linear.
Apart from that, everythings fine....
I think that it has been pretty well demonstrated that, depending on the type of cast, roughly 80% of line velocity is generated by the rod as a lever and roughly 20% by the rod as a spring.
This doesn't necessarily mean, however, that a bendy rod generates 20% more line velocity than a rigid one of the same length.
The spring element may be compensating for the loss of length during the period of the cast when the rod is used as a lever and its consequent reduction in tip velocity.
Its easy to demonstrate the beneficial effect of the spring if the rod is modelled to behave as a linear spring throughout the casting stroke. The rod, however, in my world anyway, only operates as a spring at the end of the casting stroke. If you don't model the negative effect of length reduction during the period of leverage then you run the risk of elevating the benefit of the spring effect to a position of importance that it might not merit.
Springs are modelled on the basis of Hookes Law. This just says basically that the spring extends in proportion to the load. In the argument in bendy rods it appears that the spring constant, which is something that describes the bendyness or elasticity of the spring, has been used as a true constant, a linear value, but my rods, like yours, are tapered so the spring constant is variable, non-linear.
Apart from that, everythings fine....
Casting Definitions
Many men go fishing all of their lives without knowing that it is not fish they are after.
Many men go fishing all of their lives without knowing that it is not fish they are after.
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I find Polar moment of inertia for describing the affect of torque on the rod and line. Torque applied by the caster and inertia from the rod and line from a rotational axis the caster's hand.
Acceleration may be expressed in G's force and applied to line for rod deflection loading and applied to the center mass of the rod for determining the force required to accelerate the rod alone.
Acceleration may be expressed in G's force and applied to line for rod deflection loading and applied to the center mass of the rod for determining the force required to accelerate the rod alone.
Eugene Moore
- Stoatstail50
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HA...don't set me off....flybye wrote:Good enough. Now my only problem is with the concept of "Masters"
TK
Casting Definitions
Many men go fishing all of their lives without knowing that it is not fish they are after.
Many men go fishing all of their lives without knowing that it is not fish they are after.
- Hal Jordan
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Marc
I hate being picky but mass != weight (from your first post)
Now to contribute to your question - I certainly would not use any of this in a casting lesson but since you weren't asking about tthat here are some things that can and do apply to casting mechanics:
In addition to what has already been said:
The two most important concepts imo
1. F = ma
2. Hooke's Law - bend is proportional to load
After that:
Center of mass
frame of reference
terminal velocity
wave
friction
strain
PE and KE
modulus of elasticity
momentum
gravity
power
restoring force
work
vector
scalar
load
An area that is really misunderstood - biomechanics
And last but not least when Paul Arden is casting - sound barrier, doppler effect and time dilation :p
I hate being picky but mass != weight (from your first post)
Now to contribute to your question - I certainly would not use any of this in a casting lesson but since you weren't asking about tthat here are some things that can and do apply to casting mechanics:
In addition to what has already been said:
The two most important concepts imo
1. F = ma
2. Hooke's Law - bend is proportional to load
After that:
Center of mass
frame of reference
terminal velocity
wave
friction
strain
PE and KE
modulus of elasticity
momentum
gravity
power
restoring force
work
vector
scalar
load
An area that is really misunderstood - biomechanics
And last but not least when Paul Arden is casting - sound barrier, doppler effect and time dilation :p
- Stoatstail50
- IB3 Member Level 1
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- Joined: Wed Jan 16, 2008 10:59 am
- Location: Long lost in London
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I know...I know.... I did say....Hal Jordan wrote:Marc
I hate being picky but mass != weight (from your first post)
Great list, so if we collected all these terms up do you think it would be possible to explain what they are used for, the relationships between them and how they apply to casting mechanics. ? No Data, no graphs, just words and, maybe...pictures.
It is not immediately obvious but there is a demand for this.
There are many instructors, or instructors in training, who are non-engineers and physicists who would like an understanding of the technical aspects of a cast but are not able to pass the barrier erected by the jargon and assumed knowledge beyond which they would be able to understand enough to be able to tell the difference between someone saying "this is what happens" and "I think this is what happens" ?
An area that is really misunderstood - biomechanics
Totally agree but thats a whole discipline on its own.
Casting Definitions
Many men go fishing all of their lives without knowing that it is not fish they are after.
Many men go fishing all of their lives without knowing that it is not fish they are after.
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