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Question on fletching theory
Badger:
Allen, has anyone ever dried wood vanes. I made a couple the other day and I liked the way I was able to work it. and shape it. Not so sure how well it would come out of the bow though. I am thinking an offset string might remedy that.
willie:
--- Quote ---One thing I don’t understand in this report is why one type of vanes has such a dramatic effect compared to the other. I guess it may have to do with vibration from fluttering, but it is just a guess.
--- End quote ---
Seems like a reasonable guess, Alan. The spinwing rotation rates are along the order of 4800 RPM @ 150 FPS, as reported in an associated study https://www.researchgate.net/publication/235908721_Aerodynamic_properties_of_an_archery_arrow
while the gas pros were reported to not have any rotation in the wind tunnel. Hope it doesn't take near that much rpm to add stability to a well balanced flight arrow.
avcase:
Less than 1000 rpm should be more than sufficient. 400-500 rpm should be enough to keep the arrow from bobbing up and down as it realigns itself to a constantly changing direction of travel. I am not sure how much of an effect this will have on laminar Vs. turbulent flow around the arrow. The model I was playing with always assumes turbulent flow. My real arrows seem to do about 20% better than the simulation and I figure that this might be due to the assumption that the arrow is always 100% turbulent.
It seems one is probably better off always insuring turbulent flow for a target arrow.
Alan
JNystrom:
Interesting tech talk about fletchings! Just popped in to my mind that we haven't talked about two fletch arrows. So the arrow would be fletched only with 2 feathers. Not on opposite side, but on their "original" place, only the third missing. A fletching at say, 10 o'clock, the second at 2 o'clock. I heard that Monus uses this method of fletching and well, has succes. Next time you hit your arrow and break a fletching, just rip the rest off and shoot a perfect flight arrow! Lol...
In case this is proved to be complete nonsense, i blame Mikke (m.reinikainen atleast in paleoplanet) :D.
avcase:
--- Quote from: Badger on October 21, 2017, 03:57:13 pm --- Allen, has anyone ever dried wood vanes. I made a couple the other day and I liked the way I was able to work it. and shape it. Not so sure how well it would come out of the bow though. I am thinking an offset string might remedy that.
--- End quote ---
Steve,
I’ve never tried wood vanes. I believe they used to be used on crossbow and ballista arrows. I think I would try bamboo. Tonkin cane would probably be able to take some impact if made thin. I think it would be a lot like the vanes made from horn.
Alan
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