long draw rule of thumb?

[Broken Quiver]

I changed from a 64" recurve to a 68" Morningstar. I eliminated the finger pinch and reduced my draw from 32.5 to 31.75", both of which were big deals for me. The reverse handle shortened my draw and allowed me to not concentrate on drawing onto the shelf.
 The question is, if I drop down to 45lbs on a reflex-deflex, what will this bow perform like. Is there a rule for inches and pounds? (for ex:32" at 45lb. equals how many pounds at 28".

[ron w]

If your bow is 45#@28" you can figure about 2-3 pounds per inch gain over 28". Approx. 30"=47-48, 31"=50-51, 32"= 53-54. Works the reverse also. I think that's what your asking?

[Broken Quiver]

Ron,
I think what I trying to find out is if I have a bow built for me that is 45lb @ 32", will it be more efficient than a 45lb @ 28" and if so, how much more. would it equal a 50lb @ 28".

John

[McDave]

The energy stored in a bow is proportional to the area under the force/draw curve.  The efficiency of the bow is the percentage of that energy that is transferred to the arrow.  The efficiency of the bow is a result of bow design, materials, and arrow weight, and probably wouldn't change much between a 28" draw and a 32" draw, assuming each bow is properly designed for that draw length.  Since the 32" bow will have a greater area under the force/draw curve than the 28" bow, assuming they are both drawn to 45#, it will store more energy. If they are both equally efficient, the 32" bow will transfer more energy to the arrow.  Since the 32" bow will require a slightly heavier arrow, some of that extra energy will be used in driving that heavier arrow, but I would guess that enough would be left over that the initial velocity out of the 32" bow will be higher than the 28" bow.  Would it be the equavelent of a 5# weight difference in the 28" bow?  I doubt it, but only testing will tell.

[Pointer]

Its my understanding from some research I did that an inch of draw length is equal to almost 5lbs of draw weight. If you are drawing to 32" and getting 45lbs, a guy who draws 28" would need 60lbs to match your bow performance if you shoot the same bow. This has to do with the bowstring staying in contact with the arrow for an extra 4" of power stroke

I may not have explained that correctly, but if you ever get your hands on Shooting the Stickbow by Anthony Camera, he explains it there pretty well.

I have some experience with this being a longer draw guy myself at just under 31". Shooting side by side with guys shooting 60lbs and 27-28" draw lengths, my bow was easily outperforming theirs even though I could be shooting 50lbs@31".

[Broken Quiver]

Thanks guys,
If I read it correctly, I should get more out of the bow then if I had an average draw, but too many variables for a rule.

[kennym]

Yes you are one of the lucky ones with the longer power stroke. Here is something to read, I built some test bows and I think this is what you are after....

Shot with mechanical release on Hooter Shooter

These bows were made as close as possible to each other with


64" length
.355 total stack
.003" per inch total taper
4 wood lams
2 pcs black glass
18" riser
10 strand D97 endless string
brass nockset

Here is the data,I used the same arrow for all bows(sorry,limited time with hootershooter before sending one bow to charity auction!)

The arrow weighed 437 grains

All bows chronoed at 28" draw length

Actionboo bow
48 #
181.1 fps

Maple bow
49#
182.1 fps

Red elm bow
49.8#
183.0 fps

Walnut bow
46.5#
181.1 fps [TYPO !!! Shoulda been 180.8!!]

Now for some fun info...

62" walnut bow same specs just 2" shorter
51.6#
187.8 fps

My hunting bow with string puffs 62" bow
52.9# @28"
186.5 fps
w/o string puffs same bow
192.1

29" draw-56.8# (7.69 gpp) w/o puffs
200.8 fps

30" draw -59.4# (7.36gpp) w/o puffs
209.5 fps


And if you wanna read all 13 pages, here ya go...
 http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=001491;p=1

[nineworlds9]

Originally posted by McDave:
The energy stored in a bow is proportional to the area under the force/draw curve.  The efficiency of the bow is the percentage of that energy that is transferred to the arrow.  The efficiency of the bow is a result of bow design, materials, and arrow weight, and probably wouldn't change much between a 28" draw and a 32" draw, assuming each bow is properly designed for that draw length.  Since the 32" bow will have a greater area under the force/draw curve than the 28" bow, assuming they are both drawn to 45#, it will store more energy. If they are both equally efficient, the 32" bow will transfer more energy to the arrow.  Since the 32" bow will require a slightly heavier arrow, some of that extra energy will be used in driving that heavier arrow, but I would guess that enough would be left over that the initial velocity out of the 32" bow will be higher than the 28" bow.  Would it be the equavelent of a 5# weight difference in the 28" bow?  I doubt it, but only testing will tell.

McDave did a fine job fleshing out the meat of this query.  You have a nice little advantage shooting a common poundage at a longer DL, so don't feel the need to shoot more draw weight than you're comfortable with.  And most well designed bows aren't pulling 5# / inch upwards of 28" unless they are already hitting their stack point at like 27" or less...desirable range for most folks is more like 2-3#/ inch...for you long draw guys who pull over 29" it becomes critical to choose a bow length and design that keeps the #'s / inch reasonable at the higher draw lengths.

[Broken Quiver]

Great information, thank you for the help
John

[robtattoo]

Originally posted by kennym:
Yes you are one of the lucky ones with the longer power stroke....

Y'know, as a 31"+ guy, I get real tired of hearing how 'lucky' I am. I'd kill for a 2-3" shorter draw.
Ever try hunting in a blind with a 66" bow?
Selfbow? Yah, try finding a straight stave 72" or longer.
Arrow spine charts? Forget it.
Custom bow? Yeah. There's probably 5 bowyers that will honestly accommodate you.

[**DONOTDELETE**]

Without going into a lot of double talk about DFC and energy storage.... The bottom line is that different geometric limb shapes store energy differently, in different areas of the limb.
 
There are some excellent R/D long bow designs in 60-62" lengths, and recurve designs even shorter,
that can provide an excellent string angle for a 32" draw or even 33".

As far as stored energy, vs energy transferred to the arrow goes..... The pre load at brace, which is the tension on the string at brace height, determines how much energy goes to the shaft.

 Stopping the forward limb travel clean is the most important part of a bows efficiency level.


In some limb designs with lower pre-load levels a longer power stroke is going to be less efficient because the limb travel is longer....This is a Fact... not conjecture.

You will always get a higher level of efficiency with heavier draw weight bows than you will lighter draw weights because the tension on the string at brace stops the limb mass cleaner....

[Chain2]

Robtattoo,I feel your pain but the guy who posted between us can accommodate us long knuckle draggers just fine.

[hybridbow hunter]

Originally posted by Broken Quiver:
I changed from a 64" recurve to a 68" Morningstar. I eliminated the finger pinch and reduced my draw from 32.5 to 31.75", both of which were big deals for me. The reverse handle shortened my draw and allowed me to not concentrate on drawing onto the shelf.
 The question is, if I drop down to 45lbs on a reflex-deflex, what will this bow perform like. Is there a rule for inches and pounds? (for ex:32" at 45lb. equals how many pounds at 28".

If you put a bow on a hooter shooter and shoot it with an arrow at 10 gpp and 28" and then at 29" and a heavier arrow to be again @ 10 gpp you Will see an increase in speed in the 3-4 fps range and for a stick bow in hunting weight range usually 1# increase is 1.5 to 2 fps increase in speed for a given arrow. So for each extra inch in drawlength you get something like 1.5-2# of bow. If you draw 45# @ 32" you get more or less the same performance with a given arrow shot from a 51-53# bow @28".
The strange thing is that rule of thumb works rather acurately whatever design of bow i tested on shooting machine

[Broken Quiver]

Love the aggregate wisdom here. I needed some information to apply to my hunting ethics without opening an old can. The 54lbs I'm pulling right now is ok, but at 63, it will not always be so. Besides, my oldest son has the same draw and is ready to move up to a better bow, and it will not hurt me to move down a little.
Thanks Again,

John

[**DONOTDELETE**]

Originally posted by Broken Quiver:
Love the aggregate wisdom here. I needed some information to apply to my hunting ethics without opening an old can. The 54lbs I'm pulling right now is ok, but at 63, it will not always be so. Besides, my oldest son has the same draw and is ready to move up to a better bow, and it will not hurt me to move down a little.
Thanks Again,

John

The key to that is to have a higher performance bow built for you that shoots the same arrows you are using in your 54# bow at the same speed and power, and only have to draw 49-50#.  That's what high performance bows are all about.....

btw... i could do that for you no problem.

[Tedd]

Now…if someone would just make arrows long enough for us!

[randy grider]

You will get outstanding performance from a 32" draw, even if it is but 45# weight at that draw. The additional almost 4 " powerstroke will make it seem like several #'s more, but I would not know how much. Im sure you would get better performance at 45 # than most 55# bows would at 28". Poundage makes speed, but so does draw length. I think the draw length would mean more.

[damascusdave]

Originally posted by Tedd:
Now…if someone would just make arrows long enough for us!

Someone did make arrows long enough and then Easton discontinued the Super Slam (I think the arrow industry may sell a few more arrows to wheel bow shooters)...I am sure there are still lots of them out there if you can find them...I draw no more than 31 inches and the Full Metal Jacket line meets all my needs

DDave

[Chain2]

3 Rivers Trad Only. Made in USA and long enough

[halfseminole]

Forrester Shafts makes up to 38" shafts regularly.  I draw 36"-38" depending on bow design, and for a short bow I'm using a horn composite bow, which will easily accommodate my long draw.  Anything with siyahs will be helpful, and many Kassais are built to handle draws of 36" or more.