----- 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