Cobra Limbs Tweak...

[Buemaker]

I wish I had some of the old Bowhunting World Magazine. In a couple of them the late Norbert Mullaney explains about all this. Maybe somebody still have them. Interesting stuff by the way.

[Buemaker]

Don’t mean to highjack your thread, but some interesting stuff in this article.
https://dryadbows.com/wp-content/uploads/2021/04/connie-Defining-Bow-Performance-Dryad.pdf

[Shredd]

OK Mattock...  So it is measured from the X-axis...  That makes it a little more believable as stored energy...  Like I said they did a poor job of delivering that energy...  The bottom line is that we are talking about tweaking a pair of limbs to increase it's performance...  So I am not as much concerned with stored energy as I am with the way that energy is delivered...  I can show numerous examples of bows with more stored energy are actually slower...  You may say the limbs are heavy, vibration and other things are eating up the energy...  What about, their design is lacking and just not delivering that energy like it should...  Suppose halfway through the shot cycle the string is just following it along instead of keeping pressure on the arrow and propelling it along gaining speed...
   On the hex 8 dfc that I posted...  I don't think it is the exact same bow but the DFC should be very similar...  In Tradlab there is a border bow doing 189 @ 10gpp my bow does 188 with a lot less pronounced DFC...  If you wanna say that the extra weight on the limbs is holding it back then why at 11 gpp that bow is not making any gains over my bow??  If it was a better design with all that stored energy it should be picking up speed when the arrow weight goes up when compared to my bow... 
   Another example...  My buddy has a 50 lb. Mild R/D bow...  I have a 41 lb. R/D bow...  His stored energy is way more than mine just for the fact it is 50 lb...  With a 410 gr. arrow his does 172 fps and mine does 183 fps...  That is nine lb. lighter and 11 fps faster... To match his bow in speed I would have to build a 36 lb. bow... Where is all this stored energy??  When looking for speed, to me stored energy is somewhat a myth and I don't concern myself too much with it...  I feel what you should really concern yourself with is what the chrony says, how your limbs are bending, learning what the DFC is trying to tell you and finding some kind of balance with the DFC...  You are trying to build a Bruce Lee not a line backer...

   Good stuff Bue... You aint sidetracking nuttin...

   Stag...  Grossly over weight limbs are a no-no...  But slightly heavier limbs don't matter too much...

   Hillbilly...  A map of energy into the arrow would be tits...

[Mad Max]

I don't see the Border bow on Trad lab with that speed.
Your bow it the fastest one on there.

[Shredd]

  Go to ILF limbs...

 https://www.thetradlab.com/bordercvxw

[Mad Max]

 

[Shredd]

  I just want to add another note on the stored energy myth...  I can build a bow with great numbers as the general rule would suggest, with real high numbers in the beginning and low numbers at the end...  It would show more stored energy than some of the other bows of the same model or even other models that I have made...  I could put super slim limbs on the bow to make them lighter... That bow would be a lot slower than my other bows but it would show a lot more stored energy...  That is why I feel the term stored energy is kind of useless...  That curve you see on the graph is telling you how those limbs are bending... Too much of a curve could mean there is too much limb moving and you could start losing speed...  Too little of a curve could mean you start stacking to early and you start losing speed...  Those big hooks on the those hex limbs is all about excess smoothness of draw...  If you want serious speed and probably a decently smooth draw to boot look at the Uuka limbs... Those guys are not messing around...

https://www.thetradlab.com/uuukhavx

[mmattockx]

Where is all this stored energy??  When looking for speed, to me stored energy is somewhat a myth and I don't concern myself too much with it... 

Stored energy isn't a myth as such, it is a real thing we can measure. But it isn't as important as the other details, like you say. Your Bruce Lee instead of a linebacker idea is right on I think. I have read other people talking about how changing pad angles on a takedown to change the initial string tension can significantly affect the vibration levels and speed. It is a complex system with a bunch of interconnected variables that performance can be very sensitive to.


Mark

[Mark R]

Great topic Shredd, I do a little R&D myself for my designs but nothing overly extensive as my budget and time I want to put into it will allow. Design and material make a big difference in performance no question and the only way to truely know is to painstakingly Build and test, helps all learn from the labor of love of others,  thanks all for sharing.

[Mad Max]

Those big hooks on the those hex limbs is all about excess smoothness of draw...  If you want serious speed and probably a decently smooth draw to boot look at the Uuka limbs... Those guys are not messing around...


Do you what the limbs are made of?
You don't see any wood in the stack, it's all black

[mmattockx]

Do you what the limbs are made of?
You don't see any wood in the stack, it's all black

According to Uuka those limbs are all carbon layers with no core of any type, wood or foam.


Mark

[Shredd]

[Mad Max]

It would cost a lot of money to do that.
I will get started

[Stagmitis]

So in the end is all about a bows dynamic efficiency?

[Flem]

Thats got to be one unpleasant bow to shoot. Maybe if you are a competitive archer and are need some advantage, would those limbs be tolerable. Carbon is not elastic, in epoxy it has an almost identical MOE to steel.
Be like shooting a metal bow, but lighter

[Buemaker]

https://www.google.no/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjwjtiR7Iv1AhX2SPEDHbN2DakQwqsBegQIBBAB&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DbZzhc7D7H58&usg=AOvVaw01wGBCXTQ7OtKwimRcMw4Y
Speed test Uhkka vs WW and Hoyt.

[Flem]

I see, those are very specialized limbs. Interesting bow in that video. Looks like you could mount it on your roof when not shooting and use it as a microwave transmitter.

[Shredd]

  I watch a lot of Jake K. videos...  His videos are very informative and he tries to cover all the bases but they are a bit long, a bit too wordy and I think he could cover all the info he is offering in half the time...  But maybe there are people out there and wanna watch him shoot bows for 10 or 15 minutes while he is testing them...     On that video he just looks at the curves... It just so happens that the curves and using the term stored energy follow the general rule and match the speed of the arrows...  I think all those limb designs are probably similar... One day he is gonna shoot a bow with a different limb design showing less stored energy and that bow is going to be faster...  He will then be scratching his head... But then these limbs could be a near perfect limb design that can't be beat speed wise...  I did not watch the whole video but I don't think he stated the arrow weights and such... I give him props for going a little deeper and getting into the DFC thing and that is a very slick device he uses to measure it...

   I would like to share with you what is in my head about making a better performing bow...  All these terms like dynamic efficiency, stored energy ect.ect. are all nice and dandy but to me they seem after the fact...  After you make a bow you can do all the math and say it has this and that... Can these things help to build a faster bow??  I don't know...  Maybe they can...  The only thing I am concerned with is how fast that arrow is leaving that bow...  After that you can move the wedges to get a bow that stacks a little sooner or draw a little smoother for desired shootability but you will lose some speed...  That is something that I have not messed with yet...  When I have a job of making a faster bow I am not looking at it as an olympic shooter, a engineer with blue prints, a mathematician ect. ect... I look at it as a bowyer with a hunk of wood and glass in front of me and the previous bow I made and it's DFC...  I look at the speed of the bow, how the bow is bending and the DFC... I say to myself, how can I increase the speed or what numbers do I need on that DFC to increase the speed and how am I gonna go about getting the desired numbers I want to increase it's speed...

   If anyone out there can educate me on how to make a faster bow using those other terms describing a bows performance, I am all ears...

[Appalachian Hillbilly]

I just wanna know how you are making them now! For a new guy, there is A LOT to learn! Thick glass less wood, thin glass more wood in the same stack, static tips or tips that bend, where to end the fades? Then there is carbon, uniweft, power lams, carbon weave...

I look at bows and think of things like what angle is more effecient at pulling on the string and how does this correlate to what arc the tip travels in? Bows with tips that travel in a long arc, short arc or straight up and down similar to a short limb compound....

[Shredd]

  I use .040 glass, .003 taper, power lam out to about 4 to 6", tip wedge 5 to 7", static tips...   And carbon is for sissys...   

  As for arc of limb bending I gave it some thought from time to time... That's about it...    For the most part keep your bows over 62"...  On longer bows like 68" you should probably go with shorter, snappier limbs... Make sure you have a consistent bend throughout the limb except about the last 4 to 5 " which should be relatively stiff...

These are my guide lines for a decent performing bow...

  Remember that every bow is different and may not jive with my guidelines... You got to experiment and find out what works for that design...