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Arrow Speed?????

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Badger:
Jack I will give you a simple formula that may be useful to you.
The formula is for figuring kinetic energy in an arrow and you can easily apply it to arrive at several bits of interesting info.

The formula  V x V x M / 450240 = kinetic energy

example:  140fps X 140fps X 500 grain arrow, divided by 450240 =21.76 ft#'s
lets say you had a 40# bow that was storing 33# energy. (24" draw)
33# kinetic would be 100% efficent you have 21.76# so you have an efficiency of 2176/33=66% efficient.
The way you figure your stored energy is to measure the draw weight every 1" of your power stroke add all those numbers up and then divide it by 12.

Your stored energy is reffered to as sedpf ( stored energy per draw force) typicaly on a self bow you will be around 87% of your draw weight I think. Your efficiency will also usually run between 65% and 75% using 70% to estimate speed on a self bow will get you pretty close, draw length has little effect on efficiency but does affect stored energy quite a bit. See if this helps and if it is not clear feel free to ask again. Steve

majsnuff:
Ahh? Badger, I think the correct formula for kinetic energy is velocity squared times 1/2 the mass or  VxVx(.5m)=Ek  with Ek being kinetic energy..

I checked on wikipedia to make sure.

If I am missing something here, I appologise in advance.

Badger:
Maj, the 450240 we divide it by is a constant that is used where grains are fed in for mass, it takes care of that. I am not all that big on math, this is just a standard bowyers formula we have been using. It seems to work out acurately. Steve

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