Primitive Archer
Main Discussion Area => Bows => Topic started by: kamil2910 on May 31, 2015, 07:25:25 am
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My new bow, very fast
bow lenght -64 inch
draw weight-32 lbs(28") max 30 inch
bambboo,maple,cosip
BH-5 inch
5 inch reflex
bow weight-350 gram
10 ff string
Result with chrono with 28 inch draws :)
11,4 grain/lbs-175 fps
12,9 grain/lbs-169 fps
14 grain/lbs-163 fps
I dont have a lighter arrow to shoot with 9 grain/lbs :-\
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Wow! very nice bow and very nice performance. Well done. 8)
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Damn this is a nice looking bow!
If I remember currectly, this is not the first time you use cosip as a belly wood.
What is this wood? does it have another name? I can`t find any info about it....
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That is a beautiful bow I bet it shoots sweet. Full draw please :laugh:
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Very nice bow. I can tell it is fast.
It looks a lot like this bow I made many years ago. I never chronographed this bow but I knew it was fast
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The draw is litlle with mine, i make a new heavier to flight schooting
Marc what you think 10 string of fastflight is good for that bow??
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Quite the curves on that one. Looks good. Reminds me of the handle on Egyptian composite bows.
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That bow is smokin'! Very well executed.
I've also found that what most people would call a lot of deflex is a good thing especially when your outer limbs look like that.
Impressive stuff.
2 strands of fastflight are enough for that draw weight, of course it goes without saying that you need to pad out the loops. You could certainly squeeze more speed out of it if you made an 'extreme' string. Most fastflight type string materials break at around 60 -70lbs per strand. Your bow only needs a 120# breaking strain string to be safe.
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Yep, I made a four strand just to be sure I could put in the Flemish twist.
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That does look hot, I don't know much about your release but it's possible a trained release might get even a higher speed. Your bow projects out at about 184 fps with 10 grains. Mark, myself and I am sure several others have had specimens a bit faster but 184 is excellent for any bow. With the profile that bow has I wouldn't be surprised at 190 fps.
I have been lobbying the flight board to push for a 35# class, facinating division as wood flight bows can carry designs at 35# that are much more difficult at 50# and higher. Your welcome t put your two cents worth in on this issue.
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Beautiful work Kamil! That's an all around work of art sir.
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Great bow!
It looks asymmetrical?Why did you choose an asymmetrical design?
Michael
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Any pics of this lovely lady drawn out to full draw??? ;D ;D ;D
OneBow
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very nice congrats
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very very nice
chuck
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Beautiful bow, very nice work. :)
Pappy
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That surely looks great!
As for design: I think such designs (angular DR bows with a lot of induced working reflex; similar effect is reached largely with DR or Karpowicz's low stack design) are probably very energy efficiënt, because at brace the wood surfaces are minimally strained.
An attempt to explain the presumed principle below:
A conventional straight bow is bent to a shallow C at brace, and is already strained a certain amount. This stored bracing energy is not available to the arrow but strains the wood nevertheless. This means that for a 22" power stroke and 6" brace height, you need to strain the wood for a 28" draw.
Having a much lower brace height eases this a bit, but is uncomfortable to shoot (you increase the length of the power stroke) due to string slap and very different arrow paradox.
What if you could have a 22" power stroke, have a regular brace height and still strain the wood only for a 22" draw?
Say you could keep a zero distance between much of the limbs and the string at brace, and still have a normal brace height by putting the handle (and only the handle) 5" above the rest of the bow? Enter the angular DR or other low-stack DR designs.
There, the surface wood is minimally strained at brace, as the limbs hardly bend beyond what the wood used to be as a stave (or slats of wood, in this case). Bracing energy comes from recurved limbs being forced to a more straight position, compressing the limb longitudinally. You can get very high string tension at brace this way.
Apart from Marc St Louis's example, have a look at redhawk's blog as well https://redhawk55.wordpress.com/ or Lukasz Nawalny's DR angular bows http://www.primitivearcher.com/smf/index.php?topic=24280.0
Hence, for a 22" power stroke (in a 28" draw), you strain the belly and back wood only for (a tad more than) a 22" draw. Which means you need less wood (less mass), you have less hysteresis (as you strain the wood less), and so on. All of which is advantageous in flight shooting, and in general in bow efficiency.
As said, you do need the recurving to get a high string tension at brace, but this recurving is induced with heath (steam or dry heat), and allows you to store energy internally in the limbs rather than by straining the surfaces (as for perry reflex).
Overdoing the recurving in such bows (like in the hickman extreme recurve https://www.flickr.com/photos/farflinger/5177069236/in/album-72157625386947492/) reduces efficiency again, as during the limb return the length of the lever reduces again (it carries dead weight at the tips during much of the draw or limb return, increasing inertia, despite storing more energy). See http://paleoplanet69529.yuku.com/topic/56228/Interesting-novel-high-energy-storage-recurve-design#.VW9-KPntlBc
You need immediate lift-off of the string from the recurves to have maximum efficiency.
In the bow you show here (just like in the other examples mentioned) all ingredients come together for a very fast bow.