Main Discussion Area > Flight Bows
FOC, center of pressure and performance
Badger:
Willie, say you have a 70# bow with a 125 grain tip on it. You would want about 70# spine. Take away the tip and now you need 45# spind, take away about 100 grains of arrow mass from the front of the arrow and now you are down to about 30# spine. You don't need much spine for flight arrows. The spine protects against the weight forward of center that the arrow is trying to accelerate. If there is not much weight up front you don't need much spine to still be stiff.
avcase:
--- Quote from: willie on September 25, 2017, 05:57:47 pm ---Alan, are you saying the spruce and tonkin arrows spine about the same, and weigh about the same? Just the diameters differ?
.57 deflection 22" O.C. seems soft, especially for a 75# bow. Seems like the bows you mentioned did not necessarily need to have the arrows spined as soft as they are for getting around the handles. As a generality, are most flight arrows sacrificing as much spine as possible, for the aerodynamic advantage of having minimal diameter?
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Yes, the primary difference between the spruce arrow and Tonkin Cane arrow is that the spruce arrows are a bit larger in diameter.
It is most important to have clean arrow flight out of the bow. An arrow that wiggles too much or comes out of the bow at an odd angle doesn't go very far. Especially if it is a very light arrow.
The "floating arrow" topic is an interesting one. I am still not sure how effective it is or how well it can be controlled, but I can try to show what I think is going on with some of these arrows using a rocket flight simulator.
Alan
Badger:
I am seriously thinking a change in strategy. Longer bows, longer arrows more stored energy and heavier arrows. At around the 250 to 280 range they become a little more consistent even though they might be quite a bit slower. I know ranges are more consistent at that weight. The lighter arrows always have that chance of an outlier that took off clean and stayed straight but I don't like gambling on it so much anymore. Maybe use a range of arrows from 200 to 270 grains.
Selfbowman:
--- Quote from: DC on September 25, 2017, 06:11:57 pm ---I'm sensing a Mass Principle for arrows.
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Well my wife has a 20 " draw and getting target arrows for 35# draw draw weight that come in at 264 grains is not difficult if you can spine them . My spine tester required 26" arrow. So I got a hundred 1/4" by 24" shafts and weighed them , grouped them and built arrows from different groups. The ones that weighed in the 264 gr. Total weight shot the best. That being said I tried this to see if weight of arrrow could give you spine. I used same point and fletchings set up on the different weights of shafts. It seamed to work for the most impossible client,. ;Dh Arvin
joachimM:
--- Quote from: Badger on October 01, 2017, 08:44:59 am --- I am seriously thinking a change in strategy. Longer bows, longer arrows more stored energy and heavier arrows. At around the 250 to 280 range they become a little more consistent even though they might be quite a bit slower. I know ranges are more consistent at that weight. The lighter arrows always have that chance of an outlier that took off clean and stayed straight but I don't like gambling on it so much anymore. Maybe use a range of arrows from 200 to 270 grains.
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My 2cts: will a bow that stores more energy shoot farther if the dry fire speed is the same? I wouldn't think so. Energy storage and bow efficiency are not the bottlenecks in flight archery. However, heavier combos may be at an advantage if you can shoot heavier arrows at the same speed as light arrows. The reason is that the one thing we cannot scale up or down, is the physical environment. Light arrows experience the same air density as larger heavier arrows, but relative to their mass they experience more drag because the air in which we shoot is the same. Put otherwise, heavy arrows shot at the same speed have more energy to push away the air in front of them. All else being the same (but scaled up, say 25%), heavier combos should shoot farther.
To reduce drag, we shoot the shortest and thinnest arrows possible, but the trade-off is less energy per arrow. The other option is to choose heavier and slightly longer arrows. This will indeed require scaling up the bows.
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