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pirate tech rules at WTT

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Re: pirate tech rules at WTT

Postby Kirkll » Wed Apr 29, 2009 6:16 pm

OK guys the old Mad scientist here has to come out of his cave a make a few comments here. i believe everyone here is getting a piece of it, but not putting things together as a whole....It's not JUST the stiffness, and it's not JUST the light weight tips. the stiffness gives these limbs stability and a bit of power. the light weight tips allow the limbs to move forward faster with less resistance, BUT.... the most important aspect of the combination is that the limbs STOP clean and transfers the energy into the arrow....every different limb design will have its maximum potential to store energy and transfer it to the arrow... it's finding the best combination..... The design of the bow is not the critical issue either. it's finding the the perfect combination of storing and reelasing the energy into the arrow.

here's a good example... TJ's all glass / hickory bow was deep stacked hickory cores and had a very stream lined profile. it was 66" in length and was trapped to perfection to remove weight from the tips. this bow shot. 191 at 6 3/4" brace, and 197 at a 6" brace and a light string. it also had a hell for stout riser.

The T/D Sasquatch was only a 60" glass bow with a totally different limb design with an A boo core. this is deceiving in a way, because the tip wedge and power wedge configuration added the stiffness where it needed it, and the radical reflex design much like a recurve was storing more energy. The Sasquatch is not a recurve bow.... it has deep core long bow limbs with the radical reflex of a recurve. This bow was tested at a 7.25" brace and you guys saw the numbers..... "The Design" of a bow is what makes it perform.... Period.... But the design also includes different materials used.

learning to get the maximum performance out of each design by manipulating the combination of materials used to store the energy, and transfer it to the arrow is what it's all about....i have a really good idea why Dans bow with the foam cores did so well....he found a good combination to manipulate the light weight strength of the carbon and foam and still maintain that extra stiffness for stability. This guy has a product that he should pursue a patten on. i'll say nothing further on the design for just that reason....

There's a couple bucks worth for you guys to chew on...
http://www.bigfootbows.com/
kirk@bigfootbows.com


Only archers are fool enough to want to make a composite with natural materials and man made materials, and then bend it repeatedly...
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Re: pirate tech rules at WTT

Postby Crooked Stic » Wed Apr 29, 2009 6:49 pm

Kirk put those Sasquacth limbs on a metal riser and see what happens. The stiffness of it would even make a more crisp stop back to brace let alone no flex at full draw. Maybe 10-12 feet faster.
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Re: pirate tech rules at WTT

Postby GraemeK » Wed Apr 29, 2009 7:49 pm

Hi Kirk
You are completely correct, success is finding the best compromise for the design you are trying to optomise.
With take down recurve limbs the compromise becomes that to have more recurve to achieve greater performance you need to
have greater stiffens in the cores to give the torsional rigidity necessary but core stiffness usually cones with heavier material so it all becomes a trade off.

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Re: pirate tech rules at WTT

Postby badger5149 » Thu Apr 30, 2009 11:34 am

I tend to go along with Kirk thinking as well. So many different approaches that can be effective if executed in the right combination of attributes.

You could run a complete thread on a whole bunch of single aspects.

Bow length- long bows tend to store more energy and short bows tend to be more efficient ( does it have to be this way?)

The more bend near the handle the more energy storage/ the more bend in the outer limb the more efficiency. ( wheres the happy medium?)

At one point does adding reflex become counter productive?

How can string angles be used to slow the limb tips as they near brace height after the shot?

Does reducing limb mass only help to accelertate the limbs faster or does it also help to reduce the limbs momentum allowing the arrow to more effectively slow them down? How can we apply this to limb timing?

Tiller logic- The front view of the bow should also reflect the way the bow bends and how the lams should be tapered. Thickness determines how far something can bend and the width will determine how far it will bend.

You guys are getting so close to maxing these bows out it is kind of like watching the final assault on Mt Everest. Hard to imagine the bows getting all that much faster next year. There has been a big jump each year so far. Steve
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Re: pirate tech rules at WTT

Postby dustynose » Thu Apr 30, 2009 3:38 pm

I have not much experience with modern bow materials but the numbers that were reached this year seem to touch somewhere against a naturally implemented upper speed limit. Sometimes I thought the 200 fps barrier was just a supersticious thing of measure units. Well, 200 fps are just 60.96 m/s which does not sound as magic as 200 does. But in fact I now tend to think fps is the perfectly right measure unit for arrow speed because 200 seem to be something like a natural barrier for bows that still look like a bow.
It is not long ago that I bought a chrono - in fact I did buy a chrono when I did the step from building selfbows to building bamboo backed bows. From then I noticed a difference in arrow trajectory which I wanted to measure. In my experience there seems to be a measurable speed improvement if you go from mere selfbows to bamboo backed bows of probably 5-10 fps. The main advantage seem to be the lighter weight - you need less material and to a certain extend you can create forms which a naturally grown stave just very rarely offers. I am not the kind of bowyer who can calculate the speed that can be expected from a given type of bow. I just draw humble and simple conclusions from what I could achieve so far with my own hands. And so far I can say that natural materials like bamboo and wood have certain limits which mainly express when bows from these materials take excessive set. So this is why it is for example not possible to induce that amount of reflex that can be built in a glass bow without risking too much compression force on the belly side. Even denser woods and also bamboo give up when they are exposed to too high compression forces - this is always the moment when too much reflex turns into very much set or string follow. Nevertheless, during the last months as often as I could I invited people with glass bows to shoot through my chrono to get some numbers for comparison. I had started to go the next step and to combine boo back and belly with a core built of a wood and multiple vertical boo layer core like the japanese bowmakers did, but in a much shorter design. With these designs my impression was I could gain an average 5fps over the simple boo backed bows. So last winter I started to get the impression that it might be possible to reach average modern material bow speeds even with natural material. I think the main advantage of this design is achieved by the lighter weight of the boo. At the beginning I also experimented with a highly pronounced reflex but had to learn very fast that only moderate curves work with these designs.
For me WTT III was a good opportunity to get a straight and clear information about the real potential of the materials I use. For some time I thought it could be possible to do with natural materials nearly the same what can be done with carbon and glass. But the numbers tell a very different story. As far as I can say for now modern materials are still something like 10-15 fps ahead. I know that there are better bowyers out there which can do some fps more with the materials I use. But for now I would risk to state that the upper limits for natural materials seem to be somewhere at 190 fps (asiatic horn composites excluded) probably if someone manages a design which fits perfectly the requirements and working limits of these materials. Another question that rises is how long this type of bow could reach these numbers when frequently used? It is a well known fact that fresh wooden bows are faster than a bow that has passed through a period of regular use. From my own bows I know they will loose about, say 5 fps while being shot in and then they tend to remain more or less stable. About glass and carbon I have been told that these materials do not weaken as much as natural materials so that these bows are very stable. But in fact the durability of a bow is something we cannot really measure as easy as speed because there are too many different aspects we cannot control like arrow weight, string weight and so on. Nevertheless, I would be very interested to hear something about your durability experiences.
In my head there are still some ideas how I could gain probably some more speed but this is something I will have to try next winter. When I succeed I will surely try to participate also next year, but just when I get something over 180 which is now my personal barrier. ;) Probably a bit more length, a little bit lighter and somehow stiffer outer limbs will help :) But for sure - I can do what I want - nearly 200 fps with your materials is still a different planet. But 180 fps is 200 km/h ;), just a different measure unit.... :)

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Re: pirate tech rules at WTT

Postby BK in TEXAS » Thu Apr 30, 2009 5:59 pm

Excellent posts Hanno, and Steve. Between the two of you there is a WORLD of wood bow knowledge :)

maybe some will rub off on me :D

BK
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Re: pirate tech rules at WTT

Postby Kirkll » Thu Apr 30, 2009 10:17 pm

badger5149 wrote:How can string angles be used to slow the limb tips as they near brace height after the shot?

Does reducing limb mass only help to accelertate the limbs faster or does it also help to reduce the limbs momentum allowing the arrow to more effectively slow them down? How can we apply this to limb timing?



That small list of questions right there could keep us writing theories for quite some time, and they are all good ones Steve. the two i picked out here are a couple i've been working on in my trial and error testing method for the last 6 months. along with others you mentioned too with the R/D factors.

BK mentioned something on another thread i noticed my self at WTT that may shed light on the reduced limb mass vs speed question. the fact that we have a spread of 9 fps faster to 11 fps going from 10 ggp to 9ggp ... that tells me that some bows are allowing the limbs forward motion to excellerate at a faster rate with lighter arrows than they are using heavier ones. the question very well could be answered by a combination of the two things mentioned above.
string angle, and tip mass....i believe the application of these in limb timing is a seperate issue. then we are factoring in shelf location as well.

what's your take on that Steve? we got 5 bows shooting the same number at 10 ggp and varitions of 2 fps at 9 gpp....
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Re: pirate tech rules at WTT

Postby jwillis » Fri May 01, 2009 8:51 am

badger5149 wrote:...The more bend near the handle the more energy storage/ the more bend in the outer limb the more efficiency. ( wheres the happy medium?)

At one point does adding reflex become counter productive? Steve

These topics seem to be closely related. "More bend near the handle" (that leads to energy storage) seems to be "more reflex" near the handle or at least "reduced deflex". My tests show that anything you do to reduce deflex, the more energy the bow stores. This would support the idea that a reflexed Hill-style bow has more speed potential than a r/d hybrid. It would be interesting to build one of our r/d speed bows having 2" or 3" reflex and NO deflex just to see what it would do. Use all of the other pirate tech, just eliminate the deflex. Also, there seems to be some magic amount of radius to the limb curve for each bow length. I think what Steve is talking about is at what point on the limb the curve is located. One theory I've been kicking around is that the entire limb needs to be gradually curved for gaining efficiency, not just the tips. Jim
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