Main Discussion Area > Flight Bows
Virtual Mass revisited
Badger:
--- Quote from: willie on September 28, 2020, 01:20:51 pm ---
--- Quote ---Virtual mass has very little relation to actual mass
--- End quote ---
I think kevin has a good point, Steve. My guess is that you are pointing out that arrow mass, or the virtual arrow mass, is not directly comparable to bow mass, as in grains and ounces.
--- End quote ---
Not at all, virtual mass is a measure of the amount of energy not going into the arrow. It doesn't have much to do with arrow mass or bow mass although bow mass can effect it obviously.
DC:
I gathered some arrows 300,400,500,550 and 560 grains and shot them through the chrono. Then I graphed the results and got a pretty much straight line except for a little jog with the 550 that I can't explain yet. Then I made a heavy Ocean Spray arrow that is 650 grains. I marked on the graph where I thought it would end up and it was right on. Speeds went from 175 to 240 fps. Does this straight line tell me anything?
Digital Caveman:
That's very interesting, I'd love to see the data. I wish I had a chrono and could do these experiments myself.
Depending on the measurement precision, gentle curves could look flat if their not spread out over a wide enough range of data. What if you shot a 900 or 1000 grain arrow? What about a flight arrow?
The math is looking more and more complex, I fear integrals in the near future... :-\
sleek:
--- Quote from: DC on September 28, 2020, 07:11:05 pm ---I gathered some arrows 300,400,500,550 and 560 grains and shot them through the chrono. Then I graphed the results and got a pretty much straight line except for a little jog with the 550 that I can't explain yet. Then I made a heavy Ocean Spray arrow that is 650 grains. I marked on the graph where I thought it would end up and it was right on. Speeds went from 175 to 240 fps. Does this straight line tell me anything?
--- End quote ---
From knowing the 300 grains shot the 240 fps I calculated 38.36 foot pounds of energy in the arrow. With the 650 grain arrow doing 175 fps it has 44.19 foot pounds of energy. It illustrates that heavier arrows take more energy away from the bow. That supports whats being said about Hysteresis being time sensitive. The longer the arrow is on the string, the more energy it sucks from it, and the internal frislction of the bow ( Hysteresis ) is reduced.
If you are familiar with non newtonian fluids, you know that they solidify as energy increases through them, providing more resistance to an object trying to move through them. So the slower the object moves through it the easier it can move. Compare that to a bows limbs. They behave in a non newtonian way. The faster they move, the more they dont want to due to internal friction. Im certain inertia of mass has a bit to do with this as well.
If you post the arrow weights and corresponding speed, I can calculate the energy of each arrow, and when you plot that, you may notice the energy is not a linear increase. Id posit that the energy increases tangental to the arrow weight increase.
sleek:
--- Quote from: willie on September 28, 2020, 01:20:51 pm ---
--- Quote ---Virtual mass has very little relation to actual mass
--- End quote ---
I think kevin has a good point, Steve. My guess is that you are pointing out that arrow mass, or the virtual arrow mass, is not directly comparable to bow mass, as in grains and ounces.
--- End quote ---
I was incorrect in my answer and quite honestly,, distracted when I made my reply. Im sorry about that and have edited my reply to note the fact.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version