Flipped Tips or Limb Reflex?

[HH~]

Both

Flipped pyramids are rockets.

HH~

[bradsmith2010]

any fps with 10 gpp on the rockets,,

[mmattockx]

do you suppose it would be less challenging if we made FG bows?

Yes. Or at least results would (should?) be more consistent from bow to bow, so trends would be easier to identify. Of course, the FG guys complain about the FG lams being inconsistent from batch to batch, so maybe it would be no different at all aside from dealing with slightly different types of inconsistency. 


Mark

[willie]

aside from dealing with slightly different types of inconsistency.

I believe the inconsistency with wood is primarily with set taking and when working with stresses near the elastic limit. below that level of stress, my experience agrees with your earlier observation

I have compared Super Tiller's output to David Dewey's design spreadsheet and to bows I have made. It isn't that hard to model structures and wood is not a totally wacky material that is unpredictable in its response to a load so it can be done with reasonable accuracy.

[Allyn T]

I have a feeling it would be close and depend on the wood and the tiller execution, more than energy storage,,

This is the problem with comparing two (or more) bows. Even made from the same tree or board the wood will have differences and the fine differences in tillering are impossible to eliminate. It is a very challenging problem to deal with.


Mark

That's why simulations don't show the whole picture and you'd have to build bows to compare, this is more subtle than straight math equations because you have to shape the wood yourself. The numbers don't mean a thing if you can't make the bow

[HH~]

I have several chrono's but im not shooting my SB's thru them. If they kill mature whitetails at 30 yds and elk at 25yds that's all I need to know really.

I will say this new flipped tipped pyramid I have 40@28" with a little longer riser and shorter limbs is CLEARLY this fastest SB i have ever made or seen shot at that weight. I shot it in Aug in IN and the four guys I shot with in finals, one shooting a 60@28" could not believe it was 40lbs. They current arrows i am shooting are over 10GPP 450ish. I wish i had shot this bow all three days there!! I am sure when this riser makes it's debut at the stake in a big shoot the stink will start drift dead downwind.

It is shorter than I normally shoot and the limbs do have more load on them but I also was able to drop brace height as well. This all adds up to more speed. Was not really trying to do this it was just what I had to work with in that piece of Hedge.

HH~

[mmattockx]

I will say this new flipped tipped pyramid I have 40@28" with a little longer riser and shorter limbs is CLEARLY this fastest SB i have ever made or seen shot at that weight.

Have you posted pics of this bow anywhere? I assume it is not the 'Hind Tit' bow you posted a month or two back?


Mark

[HH~]

No Sir, I have not. Looks like Arvin's target model but shorter, more pyramid at tip and reflexed bit tips are flipped more.

Shawn~

[Selfbowman]

That will be fast and smooth on the draw just guessing. Hedge is that from the stave I sent you? Arvin

[HH~]

Yes it was Arvin. Took several heat treats to get one limb straight. Grain was not straight on one side. Was a real challenge with tips that narrow to bring to proper alignment.
 
Hint, with the Hedge: if your doing real heavy pyramid bow use the straightest grain wood you can put your hands on or your going add some grey whiskers.
This bow is very consistent in way it pulls weight from 6” brace to 28”. The Super Pyramid

To me it only matters that a bow shoots where i look. Point aim and point of impact are most important to me. Has to shoot consistently with respect to those two points. How fast it does this matters little as long as it does it with the arrow setup designed to kill efficiently.


HH

[scp]

My analysis results agree that reflexing raises the stresses in the whole limb while recurve tips raise the stresses a touch more than reflexing at the base of the limb, but less as you move towards the tips. By mid limb the recurved limb has lower stresses than the reflexed limb. The recurves give higher string tension throughout the draw and slightly higher early draw weight but finish with a bit lower final draw weight. Stored energy is basically the same, as I mentioned above. Considering the smoother draw and generally lower stresses of the recurves I would say the consensus was correct.

This is a fascinating question. But I have no skill to verify the statements with math or physics. Hence I resort to common sense and common language analogies. It appears that reflexed limbs are evenly stressed; while recurved tips make the straight inner limbs work harder. As inner limbs are thicker and wider, they can take the additional stresses better than outer limbs. If so, I guess with same draw weight and materials, all other things equal, the recurve might be slightly lighter than the reflexed.

[scp]

In the end the recurved design stored the same energy as the reflexed design at a slightly lower draw weight, had lower overall stresses and a smoother draw with less stack. The differences aren't huge (because I didn't move the tips a huge amount forward), but they are definitely there.

Does that mean at the same draw weight but at slight longer draw length, the recurve store more energy than the reflexed?

[mmattockx]

No Sir, I have not.

Can you post a few pics for us to appreciate it?

Does that mean at the same draw weight but at slight longer draw length, the recurve store more energy than the reflexed?

I hadn't thought about it that way, but that would be the way it works out in the end.


Mark

[bradsmith2010]

Hedgehunter,, since you have a chrono, would you consider shooting your bow, through one, and sharing the info with us, here,, thanks in advance, B
arrow weight ,, draw weight,,draw lentgh,,string type,, and anything else you might share, photo etc,, thanks,,

[HH~]

I dont shoot selfbows thru chrono's. I made that promise to myself a long time ago. I will put a BH on a shaft and shoot it for distance with a 420-450grn arrow @28" draw when I get a chance.

HH~