The best shape for a reflexed bow?

[Tuomo]

What is the best shape for a reflexed bow? I experimented with the VirtualBow program to search for an answer. Shown here are five different reflexed designs, with a straight bow included for reference. All of the reflexed bows share the following characteristics:

* Length: 66", brace height: 6", draw length: 28"
* Draw weight: 50#
* Identical front profile, optimized for even stress distribution along the limbs.
* Taper rate 0.008
* Three-layer construction; only the core thickness is adjusted to achieve the 50# draw weight
* All reflexed designs have the tips reflexed by 100 mm (4"), measured from the belly side of the handle
* 10 grains per lbs -arrow

So, which shape is the best? By best, I mean the fastest and the one that stores the most energy. Why? Which design performs the worst, and why?

[Selfbowman]

This is my opinion.

[Selfbowman]

That design has broke flight records and won multiple IBO world championships.here is the caul.

[Selfbowman]

Here is a bambino backed Osage but I’ve done boo backed boo core and gemsbok horn belly and other combinations this boo backed Osage took some set throughout the limb. It’s best shot with a 462 grain arrow was 260 yds.

[Selfbowman]

This bow was designed by Alan Case. 64” long. I haven’t shot it in competition but it shot 460 grains 232 yds.

[willie]

So, which shape is the best? By best, I mean the fastest and the one that stores the most energy. Why? Which design performs the worst, and why?

Does maximim storage energy equate with performance?
I am curious if different designs of the same materiels are more or less efficient when delivering the energy to the arrow.  (what weight arrows are you designing for?)

[Selfbowman]

 I THINK that being said material qualities is huge in design with natural materials but also in general. It will affect the width and length of the limbs depending on the stress from reflex. And yes deflex in the handle and fades takes the stress out and makes the bow more efficient. That being said in flight you need limbs pushed to the max to achieve your goal. Just my opinion. That’s why my bows take more set . If I did it put the reflex In the ends my bows they may not take set. That design has smooth even draw weight and  makes the bow pleasant  to shoot. We all have our design choices though.

[Muskyman]

Nice looking bows selfbowman. Not to high jack the thread but, what’s the wall board behind it made of.

[sleek]

So, which shape is the best? By best, I mean the fastest and the one that stores the most energy. Why? Which design performs the worst, and why?

Does maximim storage energy equate with performance?
I am curious if different designs of the same materiels are more or less efficient when delivering the energy to the arrow.  (what weight arrows are you designing for?)

Max energy storage absolutely does not equal performance. As a matter of fact, a bow could be made to store double its energy and only deliver to the arrow a small fraction of it. I struggles with my short recurve designs stringing energy, so I started focusing on what made them more efficient at delivering that energy. Eventually I got the design sorted out. Think, the energy consumed by the 1950s big engines, but how little they delivered. Same concept.

[Selfbowman]

Muskyman the long bows are on drywall . The recurve is floorings from Home Depot.

[bjrogg]

Interesting question.

I’m not a number guy. And like already mentioned. Materials make a difference. And designs are high stress.

I’m guessing the program is with zero set?

I personally like shooting number 5 . I have a short draw though and I like the early string tension. It seems smoother at full draw also, but maybe that’s less stored energy?

I think if you could keep all the reflex with zero set the one with reflex all in handle seems like it might have the most energy?

I will be watching 

I want to know

Bjrogg

[bassman211]

All the shapes you show lack set, so that is a plus to begin with, and any one of them would make a fine hunting bow.  I can confirm that. If you are shooting to make a wood flight bow  maybe non of the above. If  chrony numbers count, and all else being equal  long sloping  narrow recurved tips  with very little deflex in the limbs that ended up with 2.5 inches of reflex is the fastest 35 lb. bow that I have made to date. With a 355 gr arrow at 25 inches of draw the bow shot from 158 to 162 through a chrony. You make fine looking heavy bows, and some laminate, so I can't speak to that. JME

[Selfbowman]

Having built only two computer  design bows I will say this. Building a selfbow and achieving the spec are a challenge to say the least. The crown gets me every time. I built the second one by the dimensions and the force draw and bend profile. Laminate bows would probably be much easier. The next one build I will build it as close to the dimensions as possible before I put a string on the bow. I know I’m not going to be as perfect as the computer but I will have not stressed the wood in any way. The other trick will be matching the properties for the design. Since I know nothing about computer design I have to leave that to the smart guys. I do think that if the properties are put into the computer and the builder matches the dimensions it will turn out as predicted. That’s a lot to expect from a Texas cowboy.🤠🤠

[Bob Barnes]

Since you are talking about laminated bows, I prefer #6.  I think a bamboo backed osage or ipe, or a tri-lam is made for that deflex/reflex design.  It makes an exceptional hunting bow that shoots as well as (or better) any glass bow.

[mmattockx]

* Identical front profile, optimized for even stress distribution along the limbs.
* Taper rate 0.008

Usually you have to adjust taper to suit the front profile and side profile of a bow. Keeping them constant isn't typically optimal between designs. What front profile did you use? I stuck with a pyramid profile as it was easiest to get the stresses even along the limb and it never needed as much taper as you have, I was always around 0.003"-0.004" to get everything even on stresses.

So, which shape is the best? By best, I mean the fastest and the one that stores the most energy. Why? Which design performs the worst, and why?

Best will most likely be whichever one has the highest string tension at brace. Worst would be the lowest tension at brace.

I never considered a side profile like #2, I mostly stuck with circular reflex similar to #3. How does #2 compare to #3 on an F-d chart? It would be much easier to build #2 the way I was doing it.

#5 gave the smoothest draw curve for me, with a lot of early weight and no stacking. How does it look in your model?

Building a selfbow and achieving the spec are a challenge to say the least.

Yes it is. You need to be within 0.005" on the thickness at worst and it is hard to do that on a stave or board bow, especially if there is much thickness taper.

Laminate bows would probably be much easier.

I found that it was. I still ended up over thickness a bit, but that is better than under.

I do think that if the properties are put into the computer and the builder matches the dimensions it will turn out as predicted.

That was my experience with the two I did based on a model.


Mark