static tips and levers

[willie]

In a nearby thread that features a bow with static recurve tips, a poster asserted

"A sharp static tends to have much higher brace tension"

Is this because the lever at the end of the limb can be considered to be "torquing" the tip, rather than simply applying a bending force?
If so, would not the outer portions of the limb, just inboard from the levers, need to be stiffer than otherwise?
Does the angle of the the levers relative to the rest of the limb matter much?
Can most agree with that singular assertion, or is more required to gain high early draw weight?

[gfugal]

I'm going to admit that I don't quite understand how recurves, reflex, and such improve early draw weight. I would love a scientific-ish explanation as well if anyone can chime in. I was under the impression that once you brace it it essentially zero's out all the work put in to get it to that point, but this must be a wrong assumption.

[PatM]

You guys are the science guys, we just make bows. 

[willie]

The balls in your court, Pat. Take a stab at it.

[aaron]

I'm not sure I agree that a sharp static has higher brace tension than a rounded static.., but here's how I explain what a contact recurve does. Think of two pencils, a regular one and a "golf" pencil (short). Both are the same thickness, but the long one is easier to bend because the ends act like levers.If you hold the regular pencil with both hands near the middle, it is hard to bend just like a golf pencil.
 When a recurve is at brace, it "acts" like a bow that is shorter- it acts like a bow that is only as long as the distance between the points of contact. This short bow is harder to draw because it is short.Hard to draw= high early draw weight. At full draw, the string lifts off the recurves, and now the bow "acts" like a bow that is longer, giving you more leverage to bend the bow. So a recurve acts like a short, stiff bow early in the draw cycle, and a long bow later in the draw cycle.

[DC]

Also, I think, because it's a "shorter" bow it has to be bent more to get the same brace height  so you are effectively further into the force curve.

[PatM]

The balls in your court, Pat. Take a stab at it.

I AM making a bow. 

[mullet]

 

[gfugal]

Also, I think, because it's a "shorter" bow it has to be bent more to get the same brace height  so you are effectively further into the force curve.

Yes, if you make the working limbs shorter by taking some of the length to add reflex it will make them bend more. But, hypothetically, imagine you have two bows with the same length working limb. One is straight and the other has some static recurves added like siyahs onto the end. the working limb is going to bend the same distance for both to get the same brace height right? Wouldn't that equate to the same early draw weight, unless there's some kind of lever thing going on like aaron said?

[DC]

Yes but we build bows to a certain final draw weight. The recurve bow gets "longer" as the string lifts off. This lowers the final draw weight. So if we have your hypothetical bows the straight one will keep climbing to a higher draw weight while the recurves weight will level off. If you retiller the straight one to the same final draw weight you loose the early draw weight.

[gfugal]

Also here's a thought experiment with bracing. Say you have a bow who's limbs are bent on a long string the same distance they usually are for 28" draw. Now let's say the same bow is braced really high, then the bow is pulled only till the limbs bend that same distance. If the fist scenario was pulling 50 lbs for that limb movement what will the second pull for that same limb movement? I think I might try this experiment on my own and see what I find.

What I'm trying to figure out is if bracing reduces the stored energy at all of if it just zero's out the brace height at 0" draw only.

[gfugal]

Yes, but we build bows to a certain final draw weight. The recurve bow gets "longer" as the string lifts off. This lowers the final draw weight. So if we have your hypothetical bows the straight one will keep climbing to a higher draw weight while the recurves weight will level off. If you re-tiller the straight one to the same final draw weight you loose the early draw weight.

So really recurves don't increase the early draw weight. They decrease the final draw weight and thus only give the illusion of increasing the early draw weight.

Thus going back to the earlier post about the bow that reached final draw but had no string let off. Since it had no string let off it didn't have any lever advantage to decrease the final draw weight. Therefore, just because it is a recurve, it doesn't necessarily mean it had better early draw weight since it didn't have string let off. That is unless there is something we are missing still.

[DC]

Yeah, I guess

[PatM]

Only a compound decreases final draw weight.

I think what happens is that people struggle to make sharp statics so they convince themselves that there is no benefit.

[bushboy]

I think of it like pretentioning a spring.