Bernd Ziesche wrote: ↑Mon Oct 02, 2023 4:47 am
Hi Graeme,
Looks to me like the fly-leg has a lack of momentum when collapsing. That's what happens when not allowing the previous bc to straighten. Doesn't need an additional reduction in rod leg tension in my exp..
Regards
Bernd
I understand momentum to be the product of mass and velocity (itself a vector) The fly leg on the failed cast is faster than the fly leg on the successful cast at the moment of launching and the "launch angle" is not significantly different. I haven't overlaid the tracks from each cast just yet, but I'll do so now. (Edit: all the data I digitised yesterday seems to be lost due to the unconventional saving system Tracker employs. I'll do this rework later when I've got time.)
Importantly, the velocities of the respective fly legs during the cast progression will be different, even with the same launch speed. This is established with Tracker and is actually one of the fundamental evidentiary data sets that supports this concept. The horizontal component of fly leg velocity increases as the loop progresses in a normal cast. That happens because the tension from the rod leg is pulling the line in the fly leg (see that snap cast video for visual proof, or ask for the tracker fly leg velocity results from any cast except these collapsed ones, where it does not accelerate.)
In these collapsed casts, the fly leg does not accelerate in the horizontal direction. It acts as a true ballistic object, gradually losing horizontal velocity, perhaps from losses due to air drag.
This is the main point of considering the loop as a wave: By controlling tension after loop formation, we can improve the cast after we've "completed the stroke". If slack is the enemy of the cast, tension is its best friend! (Note the slack between the reel and the stripping guide in the failed cast ...)
Anybody who wants the original videos from the phone (warts and all) can PM me here and I'll send you a link to download it. There are lots of examples of these casts in the files, including the series of casts made from the other direction in case wind was cited as a reason for the collapse. Many of the casts I didn't have faith in because I felt like I had unconsciously undercooked the cast. Some of the best examples occurred at the start and end of the clip, where Apple for some reason known only to themselves, speeds up the video to normal speed instead of keeping slo-mo.
Anyway, since it seems so hard for all to to see the just how
dramatically different the cast results are, I will shoot it again so that the back cast and the front cast are all visible. There will only be tip speeds in the Tracker though because video resolution is already at the limit on these ones. Going twice as wide will prevent line tracks being digitised.
Please, do not take my word for it. This experiment is repeatable in any (land) location of the world. You guys can do it for yourself. Just make sure you have dialled in the slowest possible cast you can successfully achieve before attempting it. The reason the loop collapses is the removal of tension. If your fly leg is faster than you can move the rod tip forward, the fly leg will reinstate tension in the rod leg as you attempt to kill it.
Cheers,
Graeme