Draw Force Curve for Dryad Epics, Border Hex and Others

[Thare1774]

The limbs are medium Dryad Epic static recurve limbs marked 50 pounds at 28 inches on a 19 inch riser. The limbs are being used on a 23 inch blackout Excel.I will show the draw force curve, stored energy curve, energy per weight on the fingers and the first derivative of the DFC (often referred to as the Smoothness curve), and bow efficiency.These are the first static recurve limbs that I have tested and I was surprised at what I found.Here is the basic force and energy data.

 

The following is the efficiency.

Arrows = 542 gr Speed = 170 fps Draw length = 29 3/4 inches Efficiency = 69%

 

This is higher than recent tests I did for Uukha UX100 and Win Win Inno Apex limbs, but less than what I have for Border HEX6.Following is the first derivative of the DFC. This curve has been interpreted as a measure of smoothness. Because it is the shape that is important, your can compare this to limbs of different lengths and weights. This curve measure how much force it takes to continue moving the string at each point in the draw cycle. I have posted a description of this curve over on Tradtalk http://tradtalk.com/forums/showthread.php?t=39233.I compared the Dryad statics limbs to a longbow, a bow with a conventional recurve shape, and three versions of Border limbs, including 2 from the extreme recurve family.The Dryad limbs have a large recurve with a lift point of about 27 1/2 inches. This compares to that of the Border HEX limbs, except that the Dryad limbs are static. The Border limbs achieve a long lift point while still uncoiling during draw. Note that the numbers for the Dryad limbs are so high because of the higher draw weight of the limbs compared the others tested. The unexpected result is the curve for the Dryad limbs is fairly flat after initial pre-load, like you would expect for an ideal longbow. This was a surprise to me as I describe in the Tradtalk post.

[onewhohasfun]

Okay, after looking at your second graph I can only draw one conclusion.

Huh?

[wingnut]

That's pretty cool since the Epic limb is our entry level and the HEX 6 is the top of the line.

Mike

[tenbrook]

Can you explain the math you use to get these figures?  Thanks!

[BuckeyeGuy]

I've got the same limbs in 57 lbs on my Hoyt Dorado riser and they are bad a$$.  Smooth as butter!  Thx to Mike and the guys on making a great product!!

[Thare1774]

@Mike- I emailed these results to you a while back, you may not have gotten it. But yes, I was very excited that the Dryad Epics performed so well against the much pricier Border Hex's. I recommend your limbs everywhere I go.

@TenBrook- First I do the chronograph and record arrow specs and draw weight at my length. Then I use one of the aluminum arrows with the ruler on it to draw back an inch with my Easton weight scale and record the weight. Then I draw two inches and record the weight, and I keep going until I have a weight reading for every draw from an inch to 32 inches. What this tells us is hoe the bow stacks, and these numbers are what I punch into the program to get the draw force curve. Lift point is mentioned as well. Lift point is the point during the draw on a recurve that the string loses contact with the limb. The Smoothness curve simply shows the amount of force required to draw the bow every inch further. The flater the line, the smoother the draw. The flater line shows a consistency in the draw weight over the 32".

[nineworlds9]

Yeah the Dryads feel like a longbow limb, that's the impression I got when I shot them.  Very nice, smooth.  One thing to keep in mind about the Hex's is that the ppi actually goes down once you draw them past a certain point, giving a sensation of let off, which to me makes them feel smoother.  Both great limb choices for anyone.  I recommend to anyone seriously considering either to try used versions of each or at least pick one and don't obsess over whether the other limbs are 'better', they're both great brands of limbs/ different approaches.

[tenbrook]

....

[tenbrook]

Originally posted by Thare1774:
@Mike- I emailed these results to you a while back, you may not have gotten it. But yes, I was very excited that the Dryad Epics performed so well against the much pricier Border Hex's. I recommend your limbs everywhere I go.

@TenBrook- First I do the chronograph and record arrow specs and draw weight at my length. Then I use one of the aluminum arrows with the ruler on it to draw back an inch with my Easton weight scale and record the weight. Then I draw two inches and record the weight, and I keep going until I have a weight reading for every draw from an inch to 32 inches. What this tells us is hoe the bow stacks, and these numbers are what I punch into the program to get the draw force curve. Lift point is mentioned as well. Lift point is the point during the draw on a recurve that the string loses contact with the limb. The Smoothness curve simply shows the amount of force required to draw the bow every inch further. The flater the line, the smoother the draw. The flater line shows a consistency in the draw weight over the 32".

What program is this please? Did you buy it or can I download it free?

Thanks      

Tenbrook

[Peckerwood]

The Border CXB limbs looks pretty good for an entry level limb .

[Sixby]

Thare:quote:The following is the efficiency.

Arrows = 542 gr Speed = 170 fps Draw length = 29 3/4 inches Efficiency = 69%


Bow is 50 lb at 28 so probably 56 lb at 29 3/4 that is under 10 gpp with a 542 arrow and the bow should be shooting in the 190s/ Its like you are 20 fps slow with your Chronogrphing/
Are you sure of your numbers., The efficiency rating does not seem right to me. I believe it should be higher at under 10 gpp. Also the speed seems low for that bow for almost thirty inches of draw. It should have  an efficiency in the 90s and speed in the high 180 or low 190s at least for thirty inches of draw. Seriously unless I am all wet and could well be it seems low.
I'm questioning your results here, not the Dryad bow.

God bless, Steve

[Bob Morrison]

Steve,If your all wet Steve so am I. Charts pretty much tell which is smoother. 170 FPS at almost 30" and 10GPP, just can't be right.....even at entry level....

[markliep]

The Border CX line has been replaced with the CV line - a little more stable/quicker than CX if I understand things correctly - same materials as the hex line but a conventional recurve shape - there's a great bare bow review of 5 top bb target limbs at TT -  http://tradtalk.com/forums/showthread.php?t=40124  

While I'm waiting on some CV limbs I'm enjoying a wonderful stable & smooth pair of bamboo dryad epic LB limbs that I paired to a Hoyt excel riser - super quiet stable & moves my stumping arrows with authority - hooray for ILF - M

[Sixby]

Looking good there Mike except for those numbers he posted. Those cannot be right according to the graphs and what I know about the bow. And yes that smokes the B bow imho.
I bet I can guess the numbers pretty close. Speed at 10 gpp. 193, efficiency 94percent , I purposely went lower on the speed at what I think it is LOL. I would really guess at almost thirty inches that the bow shoots 195 plus.

Am I right Mike?


God bless you all, Steve