Loop formation / rotation / translation

Walter & Group:

 

From Michael Jones..........

Gordy-

You said:

"The caster feels as though he his making only pure translation, but a

critic standing off to one side almost always noted a certain amount

of rotation mixed with it. This is also what we see in the video

studies as well. With pure translation, there can be no angular

change of the butt section of the rod."

 

So I want to update my earlier question based on this accepted observation:

Can we say that the loop 'forms' at a distinct point where rotation

overrides translation in the angular change of the rod in its' path in

the casting stroke. You can see where I am trying to go with

this...away from the body and gear, and into the line...why, it really

helps me to understand how to explain what a loop is, how it is

formed, and when it is formed, that is all.

Michael

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Michael..

Very good questions !!

The loop begins to form very close to or at the ROD STRAIGHT POSITION.  We can't be absolutely certain as to whether this happens a nanosecond prior to or after absolute RSP or at RSP because the instruments which Bruce Richards and Noel Perkins were calibrated at 80 Hz which means that measurements finer than ..0125 sec. were not possible. Intuitively, I think it occurs just after RSP...  but so close as to be undetected either by eye, feel, or the instruments so far used.

One way or the other, the loop cannot begin to form until the oncoming line can overtake the moving rod tip.  That requires a tiny bit of negative acceleration of the rod tip (because it can't happen until the rod tip slows down a tiny bit.)

I look at a fly line loop as the shape of the line as it overtakes the rod tip during the cast.

The fact that the rod tip keeps moving after RSP away from the oncoming line helps to explain why the line doesn't run into the rod.  The closer the rod tip is to the oncoming line at loop formation, the tighter (smaller) the loop.  If we want a wider loop, one way of doing this is to have the rod tip decend farther from the oncoming line at that point.

We must consider the fact that RSP only exists for a fraction of a second, since the rod tip never stops moving but goes on to counterflex followed by a brief stop and then rebound.  By the time counterflex and rebound occur, the loop is already on its way.

Interesting to note that the rod tip is moving at its greatest velocity between the STOP of the hand and RSP.

As the stroke concludes, there is much more rotation than translation.  The rotational component has overridden the translational phase well prior to both the STOP of the hand and RSP.

Gordy

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In keeping with the above, comments by Mac Brown:

Gordy,

Interesting fly pattern-checked out the upside down photo.

A few comments to Troys email-some good points but a few that make assumptions which I must disagree. The assumption that most casters would casts poor loops because of a slower rod is exactly what the industry indoctrinated to the fly casting community in the early 90's. The advertising hype marketed many rods like they would fly themselves throughout the 90's. I have heard many intructors agree on the fact that a really fast rod is more difficult for a begineer to cast. Here is why-it requires more accurate timing. So often, I have seen a client show up with a super fast rod-change them over to a high quality (Winston, GLX, etc..) and their casting instantly improves. In part, because they can feel the loads the line exerts on the rod. Hauling is also much easy to teach when the caster has a more medium rod. A longer time period to accelerate could be another way to say it. In our rod studies (87 rods tested in 1997) at WCU we concluded that even for distance with a casting group of 30 advanced casters -it was the medium rods that won the highest kudos (even when the caster stated they preffered a real fast rod-it is not what they picked in reality). We looked at rod frequency (1st, 2nd, 3rd, harmonics), deflection tests, balance points, wieght, where the weight was placed, etc... during this study.  

The part on translational rotation by example-think of the precise timing required to casting with a broom handle-we drag the rod with the broom pointing straight back toward the line in the beginning stages. When the rotation finally occurs it requires that the caster have a higher degree of timing for the acceleration. This is why many instructors will say a real fast rod is more difficult to learn on. It also is more work for the caster. I used a broom handle for demos in the mid 90's to illustrate some points-partly because I was a foe of the fast rod hype of the 90's. I think Jeff was on it the first time around because all it requires is that we adjust to a little longer stroke, arc, and increased angle in hand path to throw equal loop sizes. In fact, I think this is possible with any lever, broom, or fly rod.

The increased angle is 2 parts really-one for maintaining SLP, and secondly to aid in reduction of counterflex (because the medium rod will counterflex to a greater extent for the same line distance for the 2 rods-fast verus medium/slow).

 

Another point of RSP definition that I have read on the internet is many talk of the loop being formed right at RSP. While I think it is important to have the definition for a place to talk about the rods position during the stroke. I have looked at hours of footage during the college course at WCU with high speed footage. As we know the loop occurs in reality as soon as the fly line begins to overtake the rod tip. This happens actually a few milliseconds after the stop and after RSP (but for general discussion I can see why many use it). I guess The real correct answer is it is actually beginning to outrun the tip during the first 15-20 degrees of counterflex. This brings me to another point-RSP really seems to have 2 defintitions. One for the dynamic portion of the stroke (many forces still acting on the rod which is before counterflex). The second being RSP after counterflex when the rod is static. Not trying to confuse or muddy the waters but it seems logical.

Off to work, -tight lines, Mac

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Mac...

All should read your comments carefully.

This is why most experienced instructors chose a medium flex rod for their students.  The super fast rod is a poor teaching tool because everything happens so fast the student can't see and feel it.  We can go too far in the opposite direction, too ... in that a real noodle of a soft rod is not easy for the students to handle as the timing for this one isn't easy, either, and more tailing loops occur as the student tends to put a spike of power early in the stroke.

 

Gordy

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~