Questions regarding a perry reflexed design

[Accipiter]

So, I have this wonderfully clean belly split of ocean spray lying around, about 53" tip to tip and maybe an 1 3/4" wide, which I would like to make into a short bow for target/stump shooting and maybe some brushy short-range deer hunting. For design I'm going for a challenge: 52.5" ntn, bendy handle perry reflex with static recurves about 3-4" from the tip. Aiming for anywhere from 40-50 # at 25 or  26" This seems like it would (if i do it right, big if  ) get me a bow that was not overly stressed, due to bendy handle and perry reflex, while still maintaining low stack from the recurves. Ideally, it'll look a bit like this http://paleoplanet69529.yuku.com/topic/52132#.Uo1x5OKmYjY

Alright, now some questions! 

Thoughts on design in general? At 53" long, whats a good amount of reflex to pull my belly into before applying backing?

I'm hoping to back this with bamboo, but don't have any wide backings available on my budget (free! ), has anyone ever tried backing with two parallel pieces of bamboo, rather than 1 large piece? I have access to some very nice dense bamboo, but its only 1" around, would it be possible to take two pieces and lay them side by side, for sort of double crowned backing?

The piece has some natural reflex, maybe an inch, but since its a belly split can I just flip it and get some deflex? It seems like pulling a 1" deflexed stave into 3" of reflex would accomplish more than one that already had 1" of reflex, both for stress reduction and power.

Thanks!

[mikekeswick]

I would use only 1 piece of bamboo, shape it to match the profile of your stave widthwise. Make it thin and feather to nothing at either edge preglue-up.
If you want to get the very best from this short stave I would suggest deflexing the handle and then adding your reflex in the outer limbs upto the recurves.
The deflex helps keep the wood from getting over-stressed which of course excess reflex will cause.
Say you take a 4 inch reflexed stave and a 2 inch reflexed r/d stave. Which is under greater strain at 26 inches once made into bows? Or another way of looking at it is which would have the fresher (springier) wood?
Deflex is very useful tool on shorter bows 

[Pat B]

Perry reflex is not a design. It is a construction method for adding reflex to a backed bow. In my experience you don't want to add more than 3" to 4" of reflex. With 3" to 4" of reflex added you should end up with a flat profile or 1"+ of reflex when shot in. If more reflex is added more stress is also added which can reduce the amount of reflex in the end.
 You can add more than one piece of boo, side by side as a backing.

[Badger]

 Been doing some experimenting with backing this past month.
 The thicker backings allow the belly lam to be thinner and easier to press into the shape I like when glueing up, they also tend to hold the shape better right out of the clamps and will even gain reflex when tillering sometimes. The problem comes in if the backing is too thick then the belly can get too thin and kind of collapse durring tillering. The perry reflex benefits seem to best kick in when the backing thickness is somewhere between about 1/3 and 1/2 the limb thickness in the working part of the limb. I prefer to stay closer to the 1/3 ratio.

   I find when the backing is too thin, below 1/8 thick it tends to loose more of it's glued in reflex right out of the form. Generaly speaking around 3/16 is my favorite thickness for bows in the mid 60's in length, about 1/8" for bows less than 60" long.

[Pat B]

That's some good info, Steve. 

[Accipiter]

That's some good info, Steve.

Indeed! Its going to be a bit of an experiment for sure, but this will all be good info to keep in mind. I gotta cut and season some bamboo, but I think this project should be ready to go for this spring, which will be nice. Maybe I'll do a build-a-long (critique-a-long)!.