CREEP & DRAG 10

Walter & Group...

[GH] A brain teaser from Ally Gowans takes what many of call DRAG into the realm of science, and challenges our thinking as to what it really is

Since Ally refers to Alejandro's statement, I'll place it here :

"In the .ppt file sent by Gordy, Rick Hartman doesn't add tension in the line during the "drag" movement. The tension in the line should be measured in the Rick's left hand. This hand remains immobile, and the line doesn't really move forward although Rick's body initial movement. I believe that, in the competition casting, the forward movement of the body is more related with the momentum transfer than with adding tension to the line."

Hi Gordy,

I’ve trying to stay out of this conversation about speeds, rotations and translations.

During maths lectures I was told that a straight line is part of an infinite circle so maybe rotation vs translation is not so important and pure examples of either unlikely or impossible to determine during fly casting. Line acceleration is the important quantity.

If a rod tip speed of 100m/s is attained what line velocity is achieved?

Discussion tends to be dominated by hands and rod movement; we sometimes forget that we are casting a fly line. Its motion is determined by the momentum of its elements, energised by the rod tip and hauls for sure but not exclusively determined by those.

Alejandro’s comment re the Power Point slides is interesting. I have attached a version of the file with the position of Rick’s left hand on the first slide superimposed on the other slides. Drag – I don’t think so. Is leg movement drag too!

Best regards,

Ally Gowans

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[GH] Ally,

One could torture the brain even further:

1. I wonder if the mathematicians see the theoretical "infinite circle" as one which has expanded its diameter to the point that its curvature no longer exists!!! That would yield a straight line for any segment.

2. Pure examples of translation and rotation probable do not exist as we cast.

3. I think you are correct that line acceleration is most important.

4. "If a rod tip speed of 100m/s is attained what line velocity is achieved?"

So long as the line isn't moving through the tip top, I'd think the speed of the tip and the line speed would be equal.

If a perfect straight line path of the rod tip is not achieved (and I doubt that any caster can really accomplish that) then I'd wonder if that rod tip speed of 100m/s cannot really be expressed in terms of velocity since it would not be a vector quantity. If the tip is moving along a portion of a curve, then wouldn't its velocity be constantly changing ? (Analogy: the rotating blade of a propeller.)

Whatever we call it, seems to me that the line must move at the same speed as the rod tip so long as it isn't sliding through it.

5. The relative hand positions on the slides don't really give us an appreciation of the likely increase in tension as everything including the caster moves in the direction of the cast. The markers do help show the beginning of his haul. On slide 3, I couldn't be sure that he didn't slide back a bit.

Gordy

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[GH] From Jonathan Walter:

Hi Gordy,

Interesting discussion that leaves me with more questions. However, the way my brain works I have to formulate some sort of tentative or working definition to...well...work with as an instructor. Here I go sticking my neck out:

Creep: an unintentional movement of the rod and rod hand, mostly rotational, in the opposite direction of the unrolling loop before any intentional casting stroke is begun that adversely shortens the casting stroke.

(As an instructor I have seen 3 forms: hand creep, body creep where the student leans away from the unrolling loop unintentionally before initiating the cast, and bounce creep where the hand "recoils" forward a bit after the abrupt stop. I'll bet there are others.)

Drag: an intentional movement of the rod and rod hand, mostly translational, early to midway in the casting stroke done to remove slack from the line and help maximally load the rod which does not adversely shorten the casting stroke.

(When Mac Lord told me to delay rotation in order to tighten my loops, the words I used to think through that were PuuuuuuuuuuuuuuuuLL-Rotate!(distance cast). The video of Rick Hartman is this in spades, I think. I wish I could have seen those loops.)

Tight Loops (without drag or creep!)

Jonathan Walter

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[GH] Jonathan,

I think those are both usable working descriptions.

Your brain does NOT need to be re-wired !

Gordy

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