shorter bow with a shorter draw

[O.L. Adcock]

Dave, "On the face of it that makes sense but when I think about it I don't honestly see how two bows can be the same design but two different lengths. No matter how you slice it, changing the length changes the design doesn't it? I mean, if bow X is 60 inches long and bow Y is 68 inches long, then the designis different. The handles and limbs are different lengths so design is different."

Yep, there sure could be and that's what bowyers do is try to adjust "working" limb for different draw lengths either with bow lengths, riser lengths, ect....

"I'm wondering how, if a bow design that was for an efficiently designed 50 inch recurve could be magically enlarged in every dimension exactly the same percentage so that it was say 60 inches long, would perform? Which would shoot better?"

Yep, I've done that only the opposite direction, trying to get shorter bows to perform as well as longer. The problem is geometry. The lower the string angle off the tips the more energy a bow stores early in the f/d curve. the lower that angle the less distance the tips move for any given draw length. There is NOTHING we can do to a short bow to change that without crossing over into Turkish type bows to keep the string angle low but the tip movement is still there and excessive.

Some jump on the mass thing. Yes that's important but we have to reduce the mass a lot to see any benefit. By a lot, 100-200 usn't squat, it'd have to be 500-1000 to make a big difference. It's about a 5:1 ratio betwween limb tip weight to arrow weight. The distance/movement thing. KLook how heavy compound limbs are yet they perform and are fairly efficient. Watch one shoot, the limbs only move 1/2" or less while ours moves 5-6". That's a biggy.

Chortdraw, "Everything I built from 62" down to 54" all shot within 3 feet per. sec. of each other."

I'm looking at numbers from big name bows you'd recognize tested at 24, 26,28, and 30", 9gpp at each length. There is almost 25fps difference between the best and worse at 24". The best shoots as fast at 24" as the poor one does at 30". The poor one would have to be at least 10# heavier in draw weight to catch up. Most for sure hover around the middle. To gauge it, a decent bow should shoot about 175 AMO at 24" and 180+ or a bit better at 26".

I personally have a long draw but pay close attention to the needs of short draws since I'm married to one!    I wish she'd quit beating me on the flight range however!   ....O.L.

[Mike Mecredy]

O.l. with your cross sectional design those limbs have much less mass than a longbow without that cross sectional design.  Now you take the best, most inovated limb design available today (like yours) and put it up against a longbow with a standard, flat/trapazoidal cross section, with shorter limbs, yours, even though drawn short, will out perform it.  But not too many people make bows with limbs like you do.  When you bend the limb's cross section like that you can probably get 55# pounds from a limb around .075" thinner (or 3/16" norrower) than a limb with standard flat cross section right?

[O.L. Adcock]

Mike, Oh yes, but I'm not looking at those in the length department. The best recurves and some agressive longbows can come close to matching it however so that's not warping numbers. That's part of the point, if dropping length really helped you'd surely think a 56" recurve could match or beat a 64"+ longbow if shorter lengths helped. I don't know if you read John's post on another thread but he and I both have worked on the shorter bows independantly to see if we could come up with a way to help the shorter bows. Even using the ACS when we drop length, energy storage drops. Changing riser lengths, deflex, reflex, ect..makes minor changes but the net result is still in a negitive direction. It drives me nuts!   ....O.L.

[Kingwouldbe]

Originally posted by O.L. Adcock:
Greenhed, The notion that shorter bows perform better for those with shorter draws is a theory/myth that's been floated around so long it's accepted as "fact" when the opposite is the truth. On average, the longer bows perform better at any draw length you want to pick. If comparing bow "A" to bow "B" and the only info is at 28 or 30", which ever one performs best at 28" or 30" will also perform best at 24", reguardless of it's length....O.L.

OL, you are the myth buster,     I was under the same thinking, shorter has to be faster because it loads the limbs to the max at that draw length.

Let me see if I got this straight:

If I take, lets say Hoyt's high end recurve limbs, they make short, medium, and long limbs,

If you took the long limbs and put them on a short riser, going from 70 to 62 both drawing to 50lb@28 are you saying the 70" will always be faster, even at the same draw and weight?

Also how much differences between 62" & 64" same bow

Thanks for challenging the statuesque, and helping us think outside the box.  

[O.L. Adcock]

King, someone did that in a for real test not long ago. I'll see if I can find it. If I remember correctly going from long limbs on a short riser and vice versa they saw 1-2fps difference. That difference could easily be in the risers, not the limbs or the length. Risers just like arrows are stiffer the shorter they are.

Between 62" and 64"..Little to zero from the length. What screws up conclusions is if the question is "length" and it's effects, all other variables have to be controled or, a lot of tests have to be done and averaged. Looking at 2 different bows, variations in limb materials and risers gets involved. Riser stiffness alone can account for 4-5fps......O.L.

[Mike Mecredy]

O.L.  Don't let it drive you nuts, just do what the voices tell you, every now and then poke them with a 'Q' tip, and no matter what happens, don't do what the rice crispies tell you.

[Michl]

Blacky Schwarz tested 3 different limblenghts on the same riser at 28 inch draw lenght: 60" was the fastest,58 second, 62 was the slowest.
 www.bowreports.com

[O.L. Adcock]

psav, that was the one I'd seen. The obviosly are way different in that the "short" limbs have the stiffest tips and lowest string angle. I'm not sure how he's measureing it thou?....O.L.

[RC]

Very interesting thread. I have built about a dozen or so "junker" longbows from the same form. My 66" bows shot faster than the 62-64 bows of the same lbs and arrows.I thought it was because I was cutting some of the curve off the shorter bows.RC

[Dave Bulla]

O.L., I just had a thought.

Could longer bows be faster mainly because the tips travel a shorter distance for the same draw?  Kinda goes back to the mass/time/movement/distance thing.

I know I have a 68" Root Targetmaster that I can pull 32 inches and the tips only appear to move 2 or 3 inches.  Shorter bows the limbs seem to move a lot farther and of course the string angle changes faster too.  Now that bow is no speed demon but it's got a lot "wrong" with it from design standpoints.  Riser is straight, limbs are straight until the curves with no r/d, glass is the old crossweave stuff.  Still, it shoots quite well for what it is.  Has a little thump like a straight longbow but boy is it smoooooth to draw.

[O.L. Adcock]

Dave, "Could longer bows be faster mainly because the tips travel a shorter distance for the same draw? Kinda goes back to the mass/time/movement/distance thing."

Exactly, I mentioned that earlier. Some of the conventional "flight" records set with 36-40" recurves are going to fall to 50"+ "longbows" in the next year or two. One fell last September. The efficiency and energy storage on the 50"er sucks compared to the longer bows and I'm considering something even longer. 14" arrows with an 18" power stroke are interesting!   ...O.L.

[Boneyard Bowhunter]

I have a short draw 26". I think O.L. is correct. I have done f/d curves on different bows. What you see is that the longer bows build up weight quicker
making them more efficient. But I shoot a 58" longbow and a 60" recurve just because I like it.

[RonD]

O.L. As a short draw length and low draw weight shooter the issue of what bow and bow design to shoot for the best performance is of paramount importance to me. I am a bowhunter and really have no interest in target or 3D shooting. As a hunter the capability of the equipment to provide the mechanical means to harvest an animal is also of importance. At this time I shoot a recurve that is 46#@26", though I think I draw about 25", and have been told that with such a short draw length I should shoot a recurve as opposed to a longbow in order to get the best performance. Along with shooting a recurve my setup includes a 1916 aluminum shaft (FOC of 25%) with three four inch parabolic feathers and a two-blade 145 grain Magnus broahdead. My hunting interest at this time is in hunting hogs but am uncertain as to whether my bow and setup is enough to hunt hogs at my draw length and draw weight. Based on what you have been saying in this thread what would your recommendation be in selection of a bow that would give someone like myself optimal performance?

[James Wrenn]

When I first started shooting and building bows I went with the idea shorter was better for my 26" draw length.Several years latter and many bows later I realized the idea was wrong.My draw length is still short but my bows are long and are faster and much easier to shoot well.Short is fine when you need to fit in a tight hole but longer wins out every other place on performance and shooting manners.All wood bows can be an exception depending on who is building them however.jmo

[Ghostman]

Great thread but now I'm really confused.

I had a number of Palmer recurves in 58", 60" & 62" lengths. All had the same length riser, the limb lengths differed by 2". The shorter 58" bows had 1-1.5" less brace height and were always several feet faster than the 60 & 62" limbed bows.

Bob Morrison's bows are the same way. Bob's shorter length bows have less brace height than his longer bows. My Cheyenne's all have A risers with 56" 58" & 60" limb lengths. The shortest bows are just as fast if not a few faster than the longer lengths.

Doesn't less brace height equate to longer power stroke which give it more speed?

[mooseman76]

Makes sense Ghostman, however, if the brace height is different it isn't really apples to apples.  Try shooting all at the same brace height and see what happens.  Don't know the answer myself (and frankly I've never been one to look for a few fps), but maybe will answer your question...Mike

[shantam]

and i thought i know quit abit about bowbuilding and design........

im a noob

thanks OL

shantam

[AALLFAB]

Yea i think this is one of the most interesting threads i have seen. need to read it again a couple times to wrap my head around it. These discussions have been going strong since at least the 1930s as well as physical testing and i hope it never stops. Jim

[2treks]

Good stuff Guys, Good to see you back around O.L.
This reminds me of our talks last year. I just try to remember that low string angle and short tip movement is key. It helped my longwalker out and the resulting numbers are great. That 14" arrow and 18" powerstroke sounds fun, you got my head spinning now.(AGAIN!)

GREENHED:
since you asked for a short bow, I make a 50" recurve that does well at a short draw.
Chuck

[wingnut]

Well this thread is two years old.  I think he probably allready got his bow.

LOL

Mike