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Virtual Mass revisited
sleek:
The power stroke wave is exactly what I am referring to. I think I will refer to it as a power stroke wave theory to provide clarification from now on, PSW for short.
Willie, I like your thought process and would like to engage every possible way to disprove my idea as possible to be certain I dont look for false positives due to my own bias.
Badger, in my line of thought, the limb distortion that undoubtedly exists as we all see it often, in my opinion, can come from a frustrated wave, or, dirty wave, due to improper arrow weight, and more commonly, poor tiller that instead of setting up a proper wave on release, sends out instead, a blast of.... static? Maybe I'll just call it noise. So then, instead of the bow limbs being properly tuned, like a harmonically tuned exhaust in a car, its just wasted power getting released in an chaotic way.
Again, as usual, I reserve the right to be wrong and would welcome it.
Badger:
If the arrow doesn't use all the energy the remaining energy has to go somewhere. Low string angles make the arrow effectively heavier and help it to sap more energy out of the bow and I think we both agree that tiller shape can have an effect on that also. If set can be avoided shorter working areas in the limb will usually solve that problem.
Tuomo:
--- Quote from: willie on September 30, 2020, 07:32:14 pm ---Tuomo did a lot of work with HS photography, maybe he can comment if something as subtle as a wave in a returning limb is something he has seen, or could be detected with photography.
--- End quote ---
Yes, I made a videos of shooting heavy and light arrows but it was very difficult to see any kind of valuable information, except that with heavy arrows bow limbs are returning slower. I think this video can tell something, at least about the importance of tiller:
https://www.youtube.com/watch?v=xGgWZYny9RM
--- Quote from: avcase on September 29, 2020, 11:43:19 pm ---This is an very good analogy and very true. You will see this if you very carefully test a bow over a wide range of arrow weights. In a plot of virtual mass versus arrow weight, the virtual mass may increase with less arrow weight and then reverse and start decreasing, or sometimes it is the other way around.
Alan
--- End quote ---
Weight may be one thing but I believe that spine and the properties of the arrows are also very important. I made some years ago testing and found that same weight bamboo arrows were about 1 fps faster than wood (pine) arrows. Maybe CF arrows are also ittle faster than wooden arrows? But, there seems to be three arrow variables: arrow mass, arrow (dynamic) spine and arrow material stiffness (elastic modulus).
DC:
If there is a wave you would want it to dissipate by the time it reached the end of the limb? Somehow when I think of the wave I always think of it as starting at the tip and running toward the handle. If it's not dissipated you get hand shock.
willie:
Sleek, have you considered the possibility there might be more going on with the arrow than the bow if one arrow outshines the others on the graph?
Arrows have the primary flexing or "wave" deflection we see in slow motion where spine seems to be the biggest factor, but a close examination of the arrow shows a number of different things going on. Click the settings gear icon in this video and lower the playback speed to .25. Starting at 5:12 you will see the arrow doing a variety of flexing before it leaves the bow.
How the bow transfers the energy into the arrow might make a difference in how the limbs react and ultimately how effectively the energy is transferred.
https://www.youtube.com/watch?v=96KGWC0PB6s
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