Penobscot Bow

[Deerhunter21]

i wonder how to make it get better performance or at least make use of everything thats happening. you probably want the smaller bow on the front of the bow to snap back first and then the actual bow. because if the bow snaps back before the smaller bow, there was no point in having the smaller bow up front. the arrows gone before the smaller bow could do anything significant.

[Mo_coon-catcher]

I can definitely see a useful purpose behind them if you are limited on quality woods. The larger bow gets you the draw length and the short bow gives you the power that adds up to a bow made from high quality materials to start with. So if you have a long piece of low quality materials but can make it draw to 28” bow at a low weight that’s not powerful enough but you have a 3 foot piece of a clean strong piece, you can heavily reflex it to make it cooperate better and get lots of power. This will bring up the draw weight and arrow speed.
I made one a few years ago in the mikmak style with the string bridge going from the tip of the main bow over grooves in the heavily reflexes back bow and tying off to the handle. My initial backer bow was lightly reflexes. So when the backer bows tips pull behind the back of the handle the load transfers to the main bows limbs. If there is ANY difference in the power load when this happens it will dump all the load to the weaker side. Making a sudden heavy flex in the weak limb. So to counter this you bend the backer bow into a u shape where the tips are facing straight out,or nearly so, before brace. This way the tips are always infront of the handle and you don’t get the load dump.
The big downside is a more complicated assembly and tiller. There is lots of extra mass you have to lug around and more strings and bulk to catch on things.

[Mo_coon-catcher]

Oh and the main bow pulled 25# at 27” and was and absolute dog on its own, but add on the backer bow brought it up to 50 pounds with good early string tension and speeds in the 170s.

Kyle

[Digital Caveman]

That is a very nice looking bow.  I have never seen one with cables from the center to the tips of the small bow.  I see how tillering that must have been a challenge.

I can definitely see a useful purpose behind them if you are limited on quality woods.

That is originally why I thought the bow developed.  (It took me a while to discover that there really is good bow wood in Maine )

[bradsmith2010]

thank you M Catcher,, that is some of the best info I have rea on that type bow,,,, was your 170 with 10 gpp,,
and do you think if you sinew backed the front bow it could improve perfromance,,

[Deerhunter21]

i was thinking, if the front bow gets pressed up against the back of the bow when drawn, can this add more stress to the actual bow or make change the way the tiller looks?

[Mo_coon-catcher]

At the time the arrows I had were 625gr and 450gr and it barely shot any faster with the lighter arrows. But that speed was with the heavier arrows. I’d imagine a sinew backing wouldn’t hurt anything and may speed things up by allowing the front bow to be a little shorter, which would mean using a a stiffer spring with a longer lever (the string bridge) to potentially pull the main bow limbs even faster. So there’s potential there to make a high performer, but I’m not convinced it’s worth the effort if you already have good bow woods. It’s kinda tempting to make another with a sinew backed backer bow and the main bow out of a lighter mass wood.

Kyle

[bassman]

That was another theory why the double bow was developed because of weak wood in their area. Which I question. So what weak woods would we use to make the double bow out of if we had no strong wood in our area? Pine etc, and has anyone ever made one here to see the end results?

[bradsmith2010]

im still just trying to make the best straight bow, I like the idea of trying one,,

[bassman]

Go for it . You enjoy making bows ,so I think you would enjoy the process, and maybe the end result.

[bassman]

Wow no difference in speed going from a 450 to 625 gr arrow. That little back recurved bow must work wonders for that design. Might have to try that.