Torque in Spey Casting

[Magnus]

Gordy

I suspect that pulling back on the tip might increase the tension in the bottom leg and thus would increase the velocity of the fly compared the case with no pull back.

No place for conservation of some sort then?

[mac brown]

Here is the shot. Mark that is often times the goal which makes it difficult to teach when you said :
to rotate and translate. I do not remember anyone advocating the rod did not bend during all of this. What I said early on in this thread is that 2 very different things are going on and that was
1. A different set of muscle groups involved in the stroke that offer a greater range of motion. I feel a faster tempo can be attained during the stroke over conventional methods but I would have to set up some time gates and video to prove that one. The reality is not many folks really care about it anyway except perhaps a few dozen dudes on this site.
2. The after effect of twisting changes how much counterflex occurs. (This is evident watching the tip without video). This I am certain from using them on the stream and teaching it to advanced casters for a long time now (several decades).

It is just a different way of presenting when the time calls for it on the stream. Thanks for the shoulder guys I think I can go for a fish later on today.

[mac brown]

I attached it 3 times now and it gets kicked out. It is only like a 2 MB file. Is there not a way to put little clips up? Sorry :oh:

[mac brown]

I can email it from the phone to you Mark or Magnus and perhaps you guys know how to put it up.
Thanks

[mac brown]

Gordy,
The overall mass stays the same -no doubt. But, the relationship of fly and rod leg are always changing as is their mass. When we control loops we can slow this down or speed this relationship up. Hence, pull back for example does change the mass of this relationship because it reduces the mass of the fly leg instantaneously because it is now a shorter length than if pull back had not occurred. Rod leg has increased its mass because it now has more line contained within the rod leg.

This relationship of give and take between the rod and fly legs of the loop is what creates greater control over the outcome of the layout. Hope that helps to clear it up.

[Stoatstail50]

The reality is not many folks really care about it anyway except perhaps a few dozen dudes on this site.

I'll bet its not even one dozen Mac...

The after effect of twisting changes how much counterflex occurs.

I don't think its "how much", I think its the direction in which it occurs.

Counterflex depends, amongst other things, on the restoring force in the rod and for this to be significantly affected by twist alone seems to me to be very unlikely.

Twisting an already bent rod, however, will change the direction in which the counterflex occurs, it will tend to be more sideways rather than strictly up or down. This is what reduces the gap between the rod leg and the fly leg compared with a simple up and over casting stroke (2D Marc).

(edit) this will also have an effect on the attitude of the loop which is what Magnus was talking about in an earlier post.

[Merlin]

Gordy
Mass reduction of fly leg is an illustration of shortening. I am not refering to an effective mass reduction of the line. The physics of the loop do not change but the casting style is different: use the tip to make the loop is easy with a long lever. Then you can use fancy motions to drive the line and control delivery through the loop, e.g. a pullback.
Merlin

[gordonjudd]

Mass reduction of fly leg is an illustration of shortening.

Merlin,
I still do not understand what is getting shorter.

Are you talking about the distance from the caster's feet to the point where the fly eventually lands? Thus the shortening involved is the relative distance from the rod tip to the caster's feet at the time the fly hits the water with and without a pull back of the rod tip.

An illustration or video of how the "shortening" is measured would help me to understand what you are talking about.

I am not referring to an effective mass reduction of the line.

So "mass reduction" of the rod leg does not involve a true mass as we generally think of mass (i.e., the product of its linear mass density times its length)? In the later case it would seem that a true mass reduction might involve a pair of scissors.

Gordy

[Aitor]

I attached it 3 times now and it gets kicked out. It is only like a 2 MB file. Is there not a way to put little clips up? Sorry :oh:

Mac, you can not upload videos directly to the board. Anyway you have Vimeo or Youtube available for free.
I'd love to see some videos of those techniques.

[TrevH]

If what we are calling axial torque has a significant effect, could we not look at that by running some monofil through the rings, hang a 6 ounce sinker off the end and see what happens when we apply our axial torque?

[Merlin]

Gordy
Explanation was given by Mac in post 80. The change in mass refers to the fly leg as you pullback the line around the invisible pulley. You cannot haul with a DH rod so the mass of line outside the guides remains the same.
Merlin

[gordonjudd]

One half may be to the direction of the cast and the other half removes mass in rod leg of loop.
and
Hence, pull back for example does change the mass of this relationship because it reduces the mass of the fly leg instantaneously because it is now a shorter length than if pull back had not occurred.

Mac,
Thanks for clearing up which leg is shortening faster with pull back. That first quote (taken from post#49) had me thinking it was the other way around which caused me to ask some "apples and oranges" type questions.

Now I can also see that the invisible pulley you have been talking about is the loop, so at long last I think I am on the same page as you and Merlin.

This relationship of give and take between the rod and fly legs of the loop is what creates greater control over the outcome of the layout.

Other than shortening the distance the fly lands on the water what other effects result from having the give and take between the moving mass in the fly and rod legs being different with pull back as compared to leaving the tip in a fixed position?

Gordy

[gordonjudd]

I suspect that pulling back on the tip might increase the tension in the bottom leg and thus would increase the velocity of the fly compared the case with no pull back.
and
No place for conservation of some sort then?

Magnus,
I don't understand what you are implying with that question, as my conjecture that the fly velocity would increase as a result of some added line tension during the pull back phase assumes that energy is being conserved.

More tension (force) applied to the line over some distance would increase the work applied to the line. More work energy would result in a higher KE in the line assuming that energy is conserved.

Do you see it from some other standpoint? I think there is always a place for using energy concepts when looking at dynamics problems.

Gordy

[Magnus]

Gordy

The 'invisible pulley' metaphor leaves me cold. The way it was being invoked in this thread seemed to assume it was/is common knowledge and or in common use. It isn't.

I'd far rather read energy conservation invoked to explain how pull back works.

[mac brown]

Trev,
Not even the same thing. All of the icons that used to state the conventional cast was the same as the fly cast were grasping at unicorns.
Try the the snap t with your 6 ounce weight and let me know how that worked out.
Those that think they are the same are in the school of projectile motion for the cast. The real secret is understanding the yin/yang balance of tension. No where in this thread did anyone say we were to cast by spinning the rod alone?

Magnus, give it some time and I think the pulley will grow on you. It is not just for pull back either. It is everywhere. It is only a concept for understanding more about cast. Not just a cast, but all casts.