Fw: Fw: SLP - tracking / Physics

----- Original Message -----

Sent: Wednesday, February 11, 2009 2:03 PM

Subject: Re: Fw: SLP - tracking / Physics

Gordy, interesting stuff! This is what Walter wrote, my comments..........

Just wanted to add a bit to the previous discussion about whether applying
force in the opposite direction causes the rod to unload or simply ceasing
the application of force causes the rod to unload. Server mentioned plots
that Bruce and Noel had done showing strain vs acceleration. I can't
remember
seeing these plots or I might have seen them without realizing one of the
lines represented strain.
****I've attached that chart....
(See attached file: Rod flex-RSP.xls)

I don't know if these would really help to solve
anything anyway. Most of the acceleration of the rod tip is due to rotating
the rod and depending on the placement of the strain guages the output
may be useless.
****Input from "swing" vs. "spring" is highly variable and dependent on
several factors. One cast we studied showed a nearly 50/50 split. We
attached a strain guage to the butt of the rod a few inches above the rod
handle, then carefully calibrated the system, I'm comfortable that the
results are accurate. Much more importantly, Noel is also!

What might be useful is a plot that superimposes casting
analyzer output with slow motion video of the caster but again this may not
prove much.
*****Last weekend we recorded 16 different casts in high speed video, and
Casting Analyzer. Noel has developed software that allows us to synchronize
the two and play back together at any speed. Truly amazing stuff. Gordy has
seen one of them, we'll be making more of them available on our website
soon...

The thing is that to go from applying force in the forward direction
(the flex part of the cast) to applying force in the opposite direction
(the
counterflex part) we have to pass through a point of zero force being
applied.
It will take some pretty complex experiments to show whether the caster
is conciously applying the retarding force vs just entering a brief cruise
mode
when the unloading occurs.
*****When making a series of casts using the CA to learn about the
deceleration rate of the stop I've used radically different rates of
deceleration and get very different loops. If the caster is just along for
the ride during the rod unloading part of the cast it would seem the
deceleration rates would be the same? If the caster were to simply stop
applying force rather than actively decelerate the rod, the rod would
continue to rotate at a considerable rate through the stop which would drop
the bottom loop leg dramatically. One of the instructions we commonly give
is to "stop" the rod faster to tighten loops. There is no question that we
are consciously applying a retarding force....

Again, as you mentioned previously - like snowflakes
no two casts are identical. It may be that both points of view are valid
depending
on the caster.
*****If the goal is to make a really good cast, what the rod does cannot be
radically different from one caster to another. And that is exactly what we
see when studying great casters with very different casting styles. What
their bodies do looks different, but the CA tells us that what the rod did
was very similar.

Bruce

Scientific Anglers/3M
4100 James Savage Rd.
Midland, MI 48642 USA
Tel: 989-496-1113
Fax: 989-496-3374