Ok guys, now that I've got a few double curves under my belt, I'm looking for some feedback....and questions. I'm hoping to be able to make accurate reproductions....or at least get close to the real thing with the limited info that we have.
This bow is a reproduction of a NA sinew backed "double curve" used by several tribes (Apache, Blackfoot, etc.). Here are the stats:
- Started with 48" long stave of ashe juniper, 90% heartwood, with a slight natural deflex in the middle. Seasoned about 6 months.
- After shaping (using combination of steam and dry heat) the bow is 47-1/2" long and about 46" ntn.
- 1-1/16" wide mid limb and 1/2" wide tips. Tapered smoothly from middle to tips.
- The limbs have taken about 1-1/4" of set.
- Draw weight 45# @ 22".
- Sinew string (elk leg).
- Brace height 4-1/2".
- Shoots 320 grain arrow at 138 fps. (the arrow in the photos)
- Mass is 10.9 oz + string .4 oz (175 grains) = 11.3 oz total
- Backed with 2 thin courses elk leg sinew (1/16" thick total). The sinew was applied with fish glue and tightly wrapped with twine until hardened (2 weeks).
- Dried for 1 month before shooting and final tillering.
- Painted on back with acrylic paints and finished with a few coats of tung oil.
I tillered the bow to 16" draw without sinew. It was about 35 lb at this draw. The outer 8" of the tips does not bend...I intentionally deflexed the tips.
OK, here are some personal observations and opinions on this type of bow:
- Many of these bows have "built in" stack.....the NA bowyers were aware of stack and used it to some advantage. This bow stacks at about 22" but is smooth up to this point. The advantage of the built in stack might be to cause the archer to release the arrow at just the right draw length--by making it harder to maintain a grip (Laubin) but I don't think this is the only reason. I think the stack is a "safety" feature that helps prevent overdraw and breakage...something that could easily happen when hunting on horseback or during combat.
- The sinew doesn't add much to the performance of the bow. I have a couple others of this design (without backing) and I haven't seen a difference in performance. I think the sinew is a safety feature.
- Very little hand shock.
- Wrist slap is a problem...unless a stiff wrist guard is worn. In any case, this makes the bow noisy to shoot. I don't think the low brace height was used when hunting quietly. The bow must have been braced higher for "stealth" operations. The fact that the bowstring was tied at one end seems to indicate the need to adjust string tension and brace height.
- This particular bow has a rectangular cross section and no sinew on the sides. I think this is the easiest design to deal with. I can adjust the thickness and the width of the limbs without replacing any sinew.
I'm not sure how the originals were tillered (we don't have many full draw pics of NA's) but I think the center portion should be almost straight at full draw, with the string angle @ 90o to the tips. So far, that's the way I've been tillering all my bows of this type. There are some original bows with a very pronounced reflex in the middle (I'm not sure why) but most of the examples have a shallow reflex....making it reasonable to assume that this reflex straightens out in the majority of cases.
The grip I use has been called a Sioux grip (Laubin). The index finger takes most of the force and the others lend support. I don't use the ring finger at all with bows under 35#.
These bows are simple in design but are not easy to make. They require attention to detail, foresight, and a very good understanding of the wood you are working with. If you don't shape it just right, the wood's memory will come back to haunt you...and you'll have to live with it (you can't heat or steam the bow after the sinew is applied). Also, these bows intentionally push the wood to its limits. However, they have a certain artistic quality that makes them well worth the trouble.
(Let me know if you can't see the pics...I can make and album and post a direct link).
[attachment deleted by admin]
