Cobra Limbs Tweak...

[Longcruise]

Shredd, what does your frontal profile look like?

My formula is very similar to yours except for the power lam.

[Shredd]

About 1 3/8" at the fades and about 1/2" and under at base of tip overlay...

[Longcruise]

How far out the limb do you maintain the 1 3/8?

[Shredd]

  Straight taper to 1/2"...

[Bvas]

Shreds I commend you for your commitment in chasing speed.

I like a fast bow, and would love to “chase the speed”. But I have neither the time or budget to validate an attempt. And to be honest, I am content knowing my bows are faster than all of the vintage production recurves I own.

These are some of my thoughts(which you may have already had).

A fast moving arrow requires a fast moving string. Constant acceleration to the stop would probably be optimal. I believe this is why you want limbs to more gain weight early in the draw cycle.

To reach maximum string speed requires the limb tips going from point A(full draw) to point B(braced) as quick as possible. There are only two ways to accomplish this.
1. Get the tips moving as fast as possible.
2. Get the distance from A to B as short as possible. This can be done two ways. Get the two points closer together or reduce the arc traveled between the two points.

Sorry I don’t have any great wisdom on how to accomplish this. Just a hillbilly spewing some of the random thoughts that go thru my head.

[Buemaker]

I think Bwas have something important and interesting in his point nr 2.
2. Get the distance from A to B as short as possible. This can be done two ways. Get the two points closer together or reduce the arc traveled between the two points.

Sorry I don’t have any great wisdom on how to accomplish this. Just a hillbilly spewing some of the random thoughts that go thru my head.
This is my thinking on this. I guess we could call it short limb travel. I think one way to obtain this is by using thin longer fadeout wedges and stiffer or stiff tips. Bue square head engineer.

[kennym]

" I think one way to obtain this is by using thin longer fadeout wedges and stiffer or stiff tips. Bue square head engineer."

I agree with this, if you stiffen at riser and tips, you bend limb more/most in midlimb.  When arrow is released, the midlimb is doing the work and as it straightens, the tip moves forward faster.

At least that is the way I see it in my mind's blurry eye...

[Mad Max]

.  When arrow is released, the midlimb is doing the work and as it straightens, the tip moves forward faster.

I agree with this

[Shredd]

I was just discussing this...  That is probably gonna be my approach...  I am thinking about moving my power lam out an inch and moving my nock out a half inch...  Since the tips are static that should shorten the limb and also put move stress on the mid limb...
 
    I will post something when I make my final decision...  Sorry for dragging my feet...  I got a bit of stuff goin on...

[Cherry Tree]

Curious on what the powerlam is?? Its been mentioned a few times now..

[Shredd]

 It's wedge that goes usually 2 to 6" past your fades... It's like extending the fades...

[Cherry Tree]

Okay does it act any different then if you were to enlarge your riser (extending the fades out) or is there a advantage to the powerlam?

[Buemaker]

You could extend your riser, but you will save material if using a thin powerlam. In a take down I see no reason to use a PL, just make the wedges longer.

[Cherry Tree]

Shredd so about how much working limb are you currently running? Do you see a trend of less working limb or more? (In your designs)

[Shredd]

For me, fade to nock is about 22 to 22 1/2"...   The last 3 to 4" don't bend...  So you can say about 18" of working limb for my design...  As far as a trend for performance I try to have most of the limb working...  I see bows all the time that have a nice curvy beautiful shape in the limbs...  I think most of the time I can tell if that bow lacks in performance by the looks of it when braced and at full draw... So many bowyers go for this smooth gradual curve look...  That look, unknowingly kills speed for most of those bows...  But what they do have is a smooth draw because most of their bend is in the first half of the limb near the fades...  I am talking mainly about recurves but the basic rule covers mostly all bows...  There could be exceptions to the rule...   

   A year or so ago the boys were laughing at me, saying there was a flat spot in my limbs...  There was no flat...  It is an optical illusion... I opted for a performing limb over of a graceful curved limb...  The results 188 - 190 fps vs 180 or slower...  I think people get hung up on the way things are supposed to look vs the potential of what the limbs can do... Maybe they go for the look that sells more bows... But then they might want that smoother drawing, slower shooting, quieter bow...  I think you could probably get the same feel and quietness out of some optimally performing limbs just by using a heavier arrow... Below is a pic of the limbs with the so-called flat spot...

   I have not messed too much with different lengths...  A 64 to 65" bow seems to be a good standard length so I generally go with that...  You could probably make about 15 to 20 different bows out of one bow design by varying length, width and tapers... Even though I have learned a lot in 3 years of intense, totally dedicated bow building I feel I have just scratched the surface and there is so much more to learn...

  The bow below has the best DFC numbers on any bow that I have ever built...  High tension at brace and super smooth to draw...

[Appalachian Hillbilly]

How do you get static tips? Been thinking about how you would layup your stack to achieve that. Is it like a power lam but only in the few inches or so at the tips?

[Shredd]

  Zackly... Combination of two...  Thicker limb in that area and a tighter curve will stiffen things up...

Here is a pic of typical recurve... Notice how the outer half of the limb has a gradual curve that gets tighter and tighter as you get near the tips... The bow looks great unstrung and at brace with nice flowing curves..  But look what happens at full draw... To me, not so pretty... all the bend is in first half of the limb...  Most of the recurves I see are designed this way... I could be wrong and be missing out on something but most of these bows look like they are super smooth drawing but lack in performance of what they could have with a larger working portion of limb...

[Shredd]

  Here is a 60" Bear kodiak...  Notice how the limbs have the hook that continues to more than a third of the limb before it starts taking a D-shape bend..??  That curve stiffens things up and doesn't allow the limb to bend resulting in the first half of the limb supplying all the energy and lacking leverage for more power...

[Appalachian Hillbilly]

Think I am understanding now. I have 2 Bears and several ILF recurves.  The Bears do have  a bit of curl in the ends at brace.

How do you thicken or stiffen just the tips on  a recurve without adding the extra curl?

If you  add a short piece of lam in the stack at the end, how do you keep it in the stack and not squirt out the end? Or do you run a reverse  taper core?

[Shredd]

  I run a Hyper lam... Some call it a super lam... It has the wedges built into it...

 Stop your curve and wedge where you want the limb to stop bending... On my bow I went from a large radius straight to a small radius... It's not gradual like a french curve like you see on most recurves..