Light arrows

[Selfbowman]

So no point on a 70# bow would be around 40 in spine?  Thanks guys. Arvin

[avcase]

Arvin,
It will depend on your draw length too.

Alan

[Marc St Louis]

Arvin,
It will depend on your draw length too.

Alan

Or more specifically the length of the arrow

[willie]

Leon, I have been testing spruce from boards and larch and pine also. without a lot of stock to pick thru with still a hit and miss result, i would look to someone like wayne, the sponsor of the arrow section. he spines a lot more arrows than any of us ever will. Canada is next to europe,  right? Are there any wood arrow manufactures on your side of the pond? or just resellers?

[leonwood]

Leon, I have been testing spruce from boards and larch and pine also. without a lot of stock to pick thru with still a hit and miss result, i would look to someone like wayne, the sponsor of the arrow section. he spines a lot more arrows than any of us ever will. Canada is next to europe,  right? Are there any wood arrow manufactures on your side of the pond? or just resellers?

Thanks! I had a pm from someone with a link, will post if that works out and will also extend my search for arrow manufacturers in europe.

[Selfbowman]

Let's say 28".

[Philipp A]

how thin can one make a flight arrow from hardwoods like ash etc? Does a rain drop shape point help distance?

[avcase]

For what it’s worth, I have been working on a way of estimating an arrow’s potential based on a spine/deflection measurement of a straight arrow shaft, plus a measurement of the mass, length, and diameter of the straight shaft.  The calculation comes up with an arrow weight for a good performing barreled Flight arrow design based on the desired spine, bow characteristics, and arrow length.

For example, for a 28” long flight arrow for a 70# bow with 63 ft-lb of stored energy and 175 grains virtual mass, I get the following stats for a barreled Flight arrow:

Western Larch/Tamarack:
Finished arrow weight 350 grains, max diameter .317”/8.06mm, launch speed 232 fps

Douglas fir from a recycled book shelf:
Finished arrow weight 364 grains, max diameter .341”/8.66mm, launch speed 230 fps

Sitka Spruce:
Finished arrow weight 275 grains, max diameter .343”/8.70mm, launch speed 251 fps

So, given the different arrow diameters, weights, and launch speeds, which of these arrows will fly furthest? 

Alan

[DC]

Would you please explain the "Virtual Mass" of the bow. I'm not sure if I've heard of this.
My guess would be Spruce, Larch and then Fir

[DC]

I think i found it here s://sites.google.com/site/technicalarchery/technical-discussions-1/virtual-mass---the-key-to-understanding-arrow-speed

[avcase]

I am just using a virtual mass number for the bow to estimate how the arrow weight affects the launch speed.

Just for fun, I’ll throw in a more extreme arrow for this same 70# bow. This is from an exceptionally dense and stiff ipe board:
Finished arrow weight 522 grains, maximum diameter .296”/7.9mm, launch speed 202 fps

So this ipe arrow ends up nearly twice as heavy as the spruce arrow, launch speed is much slower, but the ipe arrow is also much thinner and much less affected by air resistance. Maybe this is best...

Alan

[DC]

Does the diameter of an arrow make that much difference in air resistance? I would have expected the skin friction to be more important and I thought the weight would trump them all, up to a point where penetration starts to suffer however. I guess diameter affects the amount of skin friction too. 10% less diameter would be 10% less skin

[Badger]

   I saw some tests done of different weight arrows to see how much they slowed down over a distance of about 30 yards I think. The difference between a 500 grain and a 400 grain was shocking. The heavier denser arrows carry much better. I wish the test was between 300 and 200 grain. That would have been more interesting. I am leaning more and more toward 260 grains up to 300 just to see how they do.

[willie]

have you ever seen an easy way to determine speed of an arrow downrange?

[avcase]

There is a new LabRadar chronograph that tracks the speed of projectiles up to 50 yards out. I would love to play with one of those. I think much of the initial loss depends on how clean the arrow is released.  It is possible to calculate the speed loss with reasonable accuracy for a perfectly launched arrow if you have a good idea of the arrow’s coefficient of drag.

I’ll give some predicted distances shortly.  It is interesting that the worst performing arrow for one set of atmospheric conditions (elevation, temperature, and wind) can become the best performing for a completely different set of conditions.

Alan