----- Original Message -----
Sent: Friday, December 15, 2006
4:07 PM
Subject: New information / casting
mechanics
Walter & Group...........
This is an important, "heads up" message on fly casting
mechanics.
During the past few weeks we've been doing some FFF committee work
which has brought to the forefront some new information derived from the
study of findings using the Casting Analyzer by Bruce Richards and Noel
Perkins (Engineering Dept. U. of Mich.)
Before being enlightened by this along with information gained from
Server Sadiki & Walter Simberski of our Group and other
engineers and physicists with whom I've spoken, I and most others were
teaching that acceleration had to increase during the casting stroke for
most efficient casts and best loops. As you know, I even used the
term, "accelerated acceleration" to make the point. I was
wrong.
We also taught that acceleration should be greatest near the end of
the stroke. Many, including me, had a sketchy understanding of the
differences betwen, "speed", "velocity" and "acceleration" often mixing
up these terms as we taught.
As I understand it, new information includes the fact that an
efficient cast with good loop control is best achieved with SMOOTH, CONSTANT ACCELERATION THROUGHOUT THE ENTIRE
CASTING STROKE.
This does not change the observation that rod tip speed increases near the conclusion of the stroke
and is maximal betwen the stop (or max deceleration) of the hand/rod
butt and the rod straight position (RSP) at which point the fly line can overtake the rod tip
yielding loop formation.
The acceleration of the rod tip during the rotational phase near the
end of the stroke is responsible for the greatest tip travel during the
stroke in a given period of time and so accounts for the increase in tip
speed during that interval.
Acceleration during this rotational phase can be considered as change
in angular velocity of
the rod despite the fact that the acceleration itself has been constant
throughout the stroke including the preceeding translational
phase. Its measurement would be that of rate of change of angular
velocity.
One observation has been that the translational phase has as one
major objective, the taking up of slack thus making the rotational phase
more efficient.
As Bruce Richards has analyzed these elements, he's found that the
best loops for distance casting have been achieved with:
1.) Smooth, constant acceleration through the entire
stroke.
2.) Longer translational phase to delay the rotational phase, thus
placing rotation closer to the end of the stroke.
From a practical teaching standpoint, he has found that the loops
improve quickly when he has taught to delay the rotational phase.
Since learning that, I've found the same thing.
All this, I feel, can dovetail very well with the simplistic concepts
of, "start slow and end fast" and, "loading move followed by power
snap", "Pop-stop", "speed-up-and-stop" which are easy for our students
to understand.
Bruce will probably write an article for the LOOP on this
subject. We'll also start to disseminate this information at our
Continued Education Courses the first of which will be at the Marlboro
Mass. Fly Show in January.
Gordy