R/D and stress

[Kegan]

Does R/D limbs put extra stress on the limbs, less, or the same, as a regular straight bow? It's more right?

[Pat B]

I'd think the inner limb would have less stress because of the deflex but the outer limb would be more stressed because of the reflex. 

[PatM]

I would say less but you use the energy more efficiently  to actually power the arrow. Less energy is wasted bracing the bow which stresses the bow less during the draw. Essentially you are using the energy typically used just bracing the bow during the early part of the draw.

[Jesse]

I would say if your comparing 2 bows ,one straight with no string follow, and one r/d with the tips even with the back of the handle" no string follow" I would think the R/d bow would be less stressed. I think the outer reflexed part has to uncoil before its stressed too much but its easy to get the inner limbs working too much and I think a lot of these r/d bows are more stressed due to the tillering not the fact that its an R/d design. They just make it a bit harder to judge what part is doing the most work. Im no expert just my opinion

[knightd]

Dont get me started. .. I agree with you all  in one way or another..

[Pat B]

Jesse, I'd think whether straight or R/D the amount of stress would be related to amount of tip movement. Because of the reflex, R/D is stressed more at brace than a straight limbed bow. That extra stress is where the extra zip comes from. (this is all theory to me  )

[Jesse]

Jesse, I'd think whether straight or R/D the amount of stress would be related to amount of tip movement. Because of the reflex, R/D is stressed more at brace than a straight limbed bow. That extra stress is where the extra zip comes from. (this is all theory to me  )

I actually don't have a good explanation the more I think about it  I can build em but I can't explain them very well   They do have higher early draw weight but gain less later in the draw compared to a straight bow so I would think they are less stressed at full draw. The high tension at brace comes from the the fact that the string is pulling more downward on the tips. Kinda like trying to pull over a tree with a rope by standing directly below it. But once the limbs start to uncoil this changes and it lets off so to speak. When the string is released and slams back home the high tension returns and gives the arrow an extra boost. I dont think the high tension caused by the the more downward angle is stressing the bow more than a straight bow and maybe less due to the deflex. The deflex also allows for ,and sometimes demands, a higher brace height. Ok I may have just confused myself again. Help me out here David or someone. Am I wrong?
 

[Pat B]

Jesse, at least you can build R/D bows. I have a hard time seeing tiller on them and usually over work the inner limb section. Like you, I can't really explain how the design works. If it works it works. If not then not!  I guess that's why I like the simplest of bows. I own and shoot R/D bows as well as recurves and straight limbed bows but if I had my druthers it would be a bow like the hickory stick bow that Grunt made. Simple but effective!

[Pappy]

Great discussion,I ant sure what yall or saying but it sounds good to me ,David lets get you started. I need to do one of these just ant sure where to start,stuck in my own little rut ,I guess.
If I have to think to much it makes my head hurt.
   Pappy

[knightd]

Jesse you are right on course in my opinion.. You did a better job explaining it than I could.. ..But I will try..  The inner limb is basically at a low brace (depending on the amount of deflex) before it is strung and when you brace it you are preloading the inner two thirds of the limb using the lever on the end. At brace height the lever is close to or at its apex this is where the high early draw weight comes from. (If you think about a chain binder you can get the idea of what I'm getting at) The outer limb isn't really  doing much work  its self until you begin to draw the bow.. .  By moving the apex and length of the lever (outer limb) you can adjust the amount early draw weight and where it's peak is in the draw curve thus changing the amount of # per inch you will gain in the early and late draw curve and where these forces unload after you release the string. when every thing unloads the outer limb causes a whip action as it tries to pass  beyond its own apex adding the extra speed to the bow. The stress in a R/D bow Is allot different than the stress in a straight limb bow. Allot of the stress in a R/D is put into it in a reverse manner so even unbraced it is under stress but when you brace it and these stressed area's reach there neutral plain you are relieving some of the stress. Basically you are manipulating the stress in the bow to your's and the bows benefit. 
 
WOW !! now my head hurts.. 

[Kegan]

Thanks everyone !

I have a beautifully clean hickory stave I wanted to make into a R/D bow. The trouble is, as I intend to have it shooting around 80# at 29", I didn't want to add even MORE stress onto the bow by trying to build it as a selfbow- I would just wait until I got more sinew and back it. But if it isn't as harsh as I was originally thinking (I was just looking for "super-string-follow-inducer" here) I want to try and build it before season, instead of after.

[mullet]

 I bet you looked all those big words up, David.  Good explanation.

[Ryano]

A deflex reflexed bows limbs are bent less at brace and full draw but have more preload then a straight limbed bow. Look at a correctly tillered full draw of a D/R bow (Like Marc's) the limbs look like they are hardly bent. The wood is definitely less stressed.

[Kegan]

Ryan- do you have a specific bow of Marc's in mind? My searching skills on here are a bit sub-par

I've started on a "test" bow, a straight bow that looks like it wanted to be a R/D bow, before attempting th nice stave I have waiting (mostly because this one has alot more wood incase I mess the tiller up).

[Ryano]

Any of them Kegan. The man knows how to tiller a R/D. 

Here's a example.
http://www.primitivearcher.com/smf/index.php/topic,14600.0.html
Notice how the limbs are only just straight at brace height, like their not even bending yet.
And how they have just a slight very smooth bend all the way to the recurved tips at full draw.