Main Discussion Area > Flight Bows
Virtual Mass revisited
Tuomo:
DC - what was the bow and its parameters? Draw weight and length (from back or belly, if back, how thick handle), brace height (belly or back)? I think that hysteresis is very low, but need those parameters for calculations.
sleek:
--- Quote from: bownarra on September 29, 2020, 12:07:43 am ---
--- Quote from: sleek on September 28, 2020, 12:09:59 pm ---
--- Quote from: bownarra on September 28, 2020, 12:26:20 am ---By the way guys - what exactly is it you are trying to work out?
--- End quote ---
I WAS WRONG IN THE STATEMENT BELOW, BUT AM LEAVING IT BECAUSE IT WAS REFERENCED IN OTHER REPLIES. sorry for yelling :)
Exactly how much wood is required to make a bow. Or more specifically, how little we can get away with.
--- End quote ---
I think you need to set out a theory first then try to prove it or not :)
At the end of the day wood has hysteresis.....you can't change that. Now what do you intend to do about it and what can you do differently that will help 'offset' these losses?
--- End quote ---
I think you may have missed where I stated I posted that while distracted. I thought this question I was answering was referencing actual mass, on another thread. I really made myself look foolish there.
As for what to do about Hysteresis, I feel with out the ability to provide a concrete argument, that it can be dealt with via efficient energy transfer..The way nature does it is via wave transmission. Im pretty set on my wave theory and seeing as how it works in so many other applications, I feel a limb tillered to release its energy via a sine wave, flowing from handle towards tips, will minimize hysteresis loses best.
I do reserve the right to be wrong...
Badger:
--- Quote from: bownarra on September 29, 2020, 12:07:43 am ---
--- Quote from: sleek on September 28, 2020, 12:09:59 pm ---
--- Quote from: bownarra on September 28, 2020, 12:26:20 am ---By the way guys - what exactly is it you are trying to work out?
--- End quote ---
I WAS WRONG IN THE STATEMENT BELOW, BUT AM LEAVING IT BECAUSE IT WAS REFERENCED IN OTHER REPLIES. sorry for yelling :)
Exactly how much wood is required to make a bow. Or more specifically, how little we can get away with.
--- End quote ---
I think you need to set out a theory first then try to prove it or not :)
At the end of the day wood has hysteresis.....you can't change that. Now what do you intend to do about it and what can you do differently that will help 'offset' these losses?
--- End quote ---
Bownarrow, I did some extensive testing several years ago on hysteresis. What prompted the tests was seeing how much more efficient shorter draw bows were. Wood has almost no hysteresis until fibers start to get crushed ( set) the virtual mass testing was used to isolate hysteresis from vibration losses. As it turns out it is one of the biggest controllable losses.
DC:
--- Quote from: Tuomo on September 29, 2020, 12:19:54 am ---DC - what was the bow and its parameters? Draw weight and length (from back or belly, if back, how thick handle), brace height (belly or back)? I think that hysteresis is very low, but need those parameters for calculations.
--- End quote ---
50#@28" from the back, handle 1 1/2" thick, BH 6" back.
A little more accurate arrow weights and speed
306-240 and 236
405-215
501-200
548-198
556-191
653-175
Badger:
It looks like your 650 grain arrow was a little slower than it should have been and your 548 grain arrow was too fast.
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