Sinew & Bow length

[Stick Bender]

This was a topic I was going to discuss with friends but decided to throw it out here ,I noticed in PA magazine that  Mike Yancy took what look to be a longer Sinew/osage bow with him to Africa & was shooting heavy arrows to kill his Wart hog ,I have experimented with longer then 60 in. sinew backed bow with mixed results , But having a longer then average draw I have a fascination with shooting the heaviest arrows at the fastest speed I can , I know there is other guys here that have made bows beyond the typical double draw length recommendation , I'm wondering if any body else has tried it for say arrows in the 750-800 grain class ? & would there be a advantage for the heavier arrows at the longer length & draw ? ,I'm sure it would boil down to design but from the pics I have seen bows made longer seem to be typical parallel limb designs ?

[PEARL DRUMS]

If a longer bow is inefficient with a sinew backing, then launching a heavy arrow from it wont change that.   

[Bob Barnes]

Some of Mike's bows are longer, and yes they are sinew backed.  His design is one that has long tapered limbs with small tips.  Maybe that contributes to the fact that they shoot well even being longer than 60".  I sinew backed a 64" osage bow recently, but the design will allow me to shorten it considerably if I decide it's too long.

[PEARL DRUMS]

Have you ever shot one, Bob?

[Bob Barnes]

I'm embarrassed to say no... but I have held them and seen Mike shoot them...and will shoot one at MoJam.     

[PEARL DRUMS]

I wasn't trying to make you feel embarrassed, sorry. I asked only because often we assume if "X" made the bow, it must be top notch. That's not always the case, as you and I well now. I doubt most of us could feel if a bow we were shooting was too long for the sinew on its back.

[Bob Barnes]

not to worry... it just made me realize that I should have already shot one of them... I've know Mike for many years.  The bows 'look' like great shooters, and I have seen a lot of bows. 

[Stick Bender]

Well I didn't state it in the OP but was thinking in my mind about the reverse strung & pulled in reflex that wouldn't be there in the self bow counter part ,figuring maybe over coming the additional mass & the longer limb profile for heavier arrows ?

[willie]

Stick,

this idea of pulling in reflex has been mentioned in other nearby threads, and discussed in relation to the drying of the sinew. I wonder if there is something to be examined as to what would work best as a belly when doing this.  Obviously a highly elastic wood has its recommendations over less then elastic for just about anything bow related, but I am thinking about the use of a stave that is already reflexed. and maybe not trying to increase deflex further , but possibly just restraining the stave to the reflex it has?

[DC]

Isn't the idea of pulling in reflex more to allow the sinew/glue to shrink as much as possible rather than get more reflex. Maybe we should start with a deflexed bow so we get all the shrinkage but not as much reflex.

[PatM]

The trick is to draw the bow more relative to bow length. Sinew backed short bows are typically drawn half their length or even slightly more.  If you have a longer draw then make the bow to a similar ratio and it will be efficient.

[bradsmith2010]

I have made sinew bows that shot well at a shorter draw,, less than half the bows length,, I was usually shooting through chrono as I tillered and was surprised at the cast before I reached the full draw goal,, so I think if tillered with that in mind a longer bow ,, could shoot well drawn less than half its length,,especially holding reflex,, thats just my experience,, as far as the heavy arrows,, I have shot 700 grain arrows from a 50# bow,, and kiled deer,,
thats not to say the 500 grain arrow would not have worked as well,, but the heavy arrow flew well and penetrated very well, thats all I know,,,

the bow I mention was about 54 inches long and started shooting really well at about 24 inches of draw,,`
ok I just measured the bow, it is 55 nock to nock, and found my notes,,
it was shooting 180 fps with 500 grain arrow,, 55# at 26 inches, I counldnt find the chrono results at 24 yet still looking,,

[Stick Bender]

Well I was thinking in the sense of a bow similar to the one in the pic that one only has 18 in. working limbs it's being pulled to 31 in. In the pic 65 ntn so I was thinking same dimensions but only the working limbs sinewed & reflexed say 5 in. it seems it would be highly stressed with out adding mass and probably would shoot a heavy hunting arrow at a reasonable speed ? DC why wouldn't you want the reflex ? Patm is that design doing close to what you suggested ? Brad dead is dead regardless of weight... Lol  but Mikes warthog killer got the cob Webbs of some old ideas ! Could do it with recurves but just like the way strait limb statics shoot !

[PatM]

Yeah, that's idea. Limit it to working portions and work them hard.

[Bryce]

Have you ever shot one, Bob?

I'm embarrassed to say no... but I have held them and seen Mike shoot them...and will shoot one at MoJam.     

I wasn't trying to make you feel embarrassed, sorry. I asked only because often we assume if "X" made the bow, it must be top notch. That's not always the case, as you and I well now. I doubt most of us could feel if a bow we were shooting was too long for the sinew on its back.

I’ve shot one and your right on pearly. Doesn’t matter who made it.
If A bow is a dog it’s a dog, can it still kill? You bet.