draw length/bow weight/arrow speed

[sledge]

when i returned to archery last year, the man who led me told me that 1" of draw length was roughly equal to 5# of draw weight, regarding arrow speed.

he was referring to compound bows at the time, and assuming weight would remain the same.

with a stickbow, the weight goes up with draw length.

is it reasonable to assume that an additional inch of draw equals 7 or 8 pounds of weight with a longbow, in  terms of arrow speed?  

or is it, (as i suspect ), not that simple?

[JRY309]

Most traditional bows will add 2.5 to 3# per inch over the draw weight listed on them.Alot will depend on design overdraw on a shorter bow you will hit the wall and it will stack the weight more then 3#.You will also get a speed increase.

[swampthing]

A bow that can handle your draw length without stacking:
    2-3# per inch of draw.
    From 25-28" of draw avg. about 10fps per inch of draw, past 29" you may avg. 6fps per inch.
  For every pound of draw weight, increase or decrease, you can expect an avg. of 1fps difference.

[Orion]

I pretty much agree with Swampthing, except my experience with a number of bows, and reading about the experiences of others, I'd say it's closer to  has 1 1/2 fps per pound of draw weight.  Pretty close.

[Archie]

Sledge, I believe I know what you mean to ask ....

"If I shoot a bow that, pulled to my 31-inch draw is 45 pounds, does it have equivalent power/speed to that of a bow that, drawn to 28 inches, is 52 or 55 or 58 or xx pounds?"  

Of course, my numbers are random and hypothetical, but you probably figured that out.  

How can we compare the longer-draw bow with respect to a standard (28-inch?) draw?

I hope someone can give a reliable answer to this, because I want to know the answer, too.

[sledge]

you got it, archiie, except i'm south of 28".
25", wondering if i should try to stretch out to 26".

all of you have been helpful, though.

thanks.

joe

[Flying Dutchman]

Increasing your drawlenght means your bow will deliver more force. Some say that is 2,5 to 3 lbs per inch more. That's pretty close for bows around the 50 lbs.
I always calculate 5% per inch more. If a bow is 50 lbs @28", it will deliver 5% more at 29 and that is 2,5 lbs indeed. So at 29 inch that is 52,5 lbs. At 40 lbs it will be 2 lbs more and at 60 it will be 3 lbs more.

What does this mean regarding to arrowspeed? Well, increased drawlenght means more lbs, making your arrow relatively lighter.

A calcuation: Suppose you have a bow of 50lbs@28". Your arrows weight 500 grains. Then you will shooth as arrow weight: 500/50 = 10 gpp.

Suppose you draw 30". Then the bow will deliver 10% more lbs: 1.1x50 = 55lbs. Your arrowweight wil go down: 500/55 = 9,1 GPP

A difference of 1 GPP will give you 10 fps more speed (as an average, depending on your set-up)

However, you won't shooth the same arrows when drawing 5 lbs more :)You will have to go higher in spine value and that will make your arrow heavier, loosing the advantage of an lighter arrow.

Or you can lower your front load (broadhead, insert or fieldpoint) with 25 grains to adjust the 5 lbs more, making the arrow even more lighter and giving more speed. But this will affect your FOC (making it lighter)...

[manitou1]

Okay... here is something I am interested in.  I think it touches on the above subject matter.

If you take two same make/model bows and one of them is 50#@28" and the other one is 50#@32"... and you shoot the same GPP out of both, will the 32" bow shoot faster?  I have read that it will on several occasions, but the writer(s) never gave supporting justification. Maybe because the longer arrow is in string contact for a longer period of time? Dunno.

[swampthing]

First things first. "GET A LIGHT BOW" to learn your form with!!!!!
40#-45#@28" tops. If you feel that you have to "work" or "apply muscle" anywhere in the draw cycle it is too heavy to start out with. Yeah, coming back after a lay off is like starting over again, take your time, it will be worth it.
Once YOU get the hang of it after a month or so {at least every other day shooting at stumps and what have you} then you will be in a much better position to make these time consuming and expensive decisions based on your needs.
45# @26" w/450g arrows and sharp broadheads kills a lot of stuff, just ask the natives that have done it.....  good luck
 

Draw length will play a big role in arrow speed........
Long draws have more power......
Don't fret, not that you are ha ha, if you can, shoot heavier bows around 60# and don't sweat the small stuff, pull it back to where it goes and shoot. Maybe look at your form and make sure you are not collapsing thus loosing inches there....