Primitive Archer
Main Discussion Area => Bows => Topic started by: ken75 on November 23, 2010, 11:47:45 pm
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this was an experiment with lever length versus working limb length that was inspired by a conversation with rich r. hickory 58 inch tip to tip ten inch working limbs and 15 inch levers 44lbs at 28 2 inch fades down to 1 1/4 at lever fades. guessed on the tiller profile , and ill flight shoot tomorrow after my midnight shift. keep in mind this was just an experiment to see what improvements to cast lever to limb ratio would make
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kooi (1996) predicted that the bow with longer "ear" may show a better force-curve, but the efficiency could be lower and hence the final results are not much different. It woud be nice to hear that someone doing the wet experiment on this matter.
The "ear" angle, however, was predicted to play more role on the final result.
http://www.bio.vu.nl/thb/users/kooi/kooi96.pdf
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Ken,
I'm looking forward to your results! Nice looking bow!
Frode
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Ken,
That brace and full draw pic both look about too good. Looks to me that the levers being longer makes the workin limb bend less to get the same draw length.......cant wait to see how she does on cast, guess that will be the true indicator. Also like that low brace height maybe the longer power stroke will give some more distance too.
Hell man, get 'er shot.....the suspense is killin me.
That whole bow is just way sexy looking.
rich
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Ken very unique expiriment! How does it shoot??? I would assume cast would either be fair or it may be kinda like the turtle bow as not much kinetic energy is being made with the short bending limbs. It looks cool let us know what happens
AA76
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Well, since the bending portions of the limbs taper, there is a very small segment, that stores the biggest part of the energy...
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I will speculate that cast will be fair but not great, as said above stored energy and fdc will be good but efficiency will suffer. As the arrow approaches brace height the weight of the arrow increases dramaticaly as far as the bow is concerned because of leverage angles. The arrow is trying to stop the limb tips from mving past brace. A long stiff lever carries quite a bit of momentum on it's own and the arrow cannot slow the tips down as effectively, this might manifest iteself in handshock or just some energy lost to limb vibration. Now take that same bow with a very heavy fishing arrow for instance and it would likely outperform one with shorter levers, the heavier arrow would be better able to control the limb tips. Steve
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I like it. It has that look of deviance. Don't look like it would do much, but we know it has that hidden energy. My first one that turned out to be a hybrid. Is a very hard shooter. Working on the next, but my bandsaw blade broke 3" from having the limbs cut.
Rich has given me allot of info on these and it keeps me intrigued. Good luck on the shooting session. Can't wait to hear the results ;)
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It may be worth visiting the "Hickman stiff limbed theoretical bow" thread over on Paleoplanet
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Very good to see experiments that we all can learn. I like Steve's prediction and would have to agree. Often where we increase advantage in one area, we will suffer in another. It is always a balancing factor.
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That is a really cool looking bow. It will be very interesting to see how it shoots. Here's a idea... since this is an "experiment" bow anyway, wouldn't it be interesting to shoot the bow with a 10 gpp arrow and measure the performance...possibly even take a chrono reading and make a FDC...then shorten the levers some and test it again with a 10 gpp arrow...then shorten it some again and test it again? If you do this, I'm thinking that you would want to shorten the levers from the mid-outer limb instead of piking it. Jim
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alright first of all thanks for all the input im glad others are interested . as i said the tiller was a guess if you look at the blown up pic by Frank the working limb bends like a mini regular limb i think u have to ignore the levers and watch the workin limb JMO.
the only thing i truly disagree with is the comparison to the turtle bow , which for those that dont know was a log with a bow in the center, these levers are 3/8th to 5/8th and hardly like Hamm's turtle bow that if memory serves me made it 21 feet !
i did the flight shoot with it this morning in not so fare conditions rainy and foggy, however 460gr arrows with ma2 broadheads had a 148 yrd. four shot average.
this one was 17 lbs lighter than the bow with 15 inch working limbs and 11inch levers which got 183 yrd average. so i think its fair but not as good as it could be . Rich has said before that equal lever ,limb length ratios were optimum and i agree after this expirement.
i would start removing lever length but that would require retillering down to 44lbs each time to get proper judgement of effiency, limbs are less than a 1/4 so im done with it , thanks everyone ! ;D
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few pics
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Thats decent performnace, I bet you could thin out the thickness on those levers and get a bit more out of it without changing the tiller. Steve
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Nothing wrong with experimentation. As a young student in chemistry, in physics, and in biology, we conducted experiments that had been done countless thousands of times, with the results well know. Some say pointless, because the results were already well documented.The exercise is not pointless, because it is the process itself that brings the information into understanding, and from understanding the ability to perform. Besides, unusual bows make for interesting conversation.
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Why not skeletonize the tips? It would be interesting to see the performance increase if you could keep them the same stiffness but lighten them considerably.
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guess i could drill a bunch of holes in the levers , is that what ur talkin about Patm
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what if you kept the levers stayed the same width and thickness to the fades? would this put to much stress on the whole thing?
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Hey Ken,
If 148 was your average then ya must had at least one to 150 or so. For a 44# bow of that length, I dont believe that is bad at all. Unless ya want a pure flight bow think about a deer at 20 yards or less.....when it (the arrow) hits it's still got about 130 yards of power left in it and about 12-18" of critter to get into.......still gonna be a damned fine huntig bow. I know fer afact yer allready lookin at some tweeks, aint ya?
Emperically gathered data is reliable info for real world situations, and better still you have the confidence in the equipment to absolutely know it's a good set up. JMO
PS: gonna have the 10/13 ratio 53" ready to go shortly will see how it does and compare notes, eh?
rich
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hillbilly i did that on the last one the 15/11 ratio has 1/2 inch width for their length. its a little thicker in the belly up next to the lever fade but very slender tips thats the one that i got 183 yrds out of
Rich i think your right on that its a viable hunting bow, i still may do a little tweakin on it though. lookin forward to seeing the new one
on a side note i got 166 yrds out of an unbacked (snakeskin) black walnut recurve thats 48 lbs , some of your wood
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Gosh that's a pretty bow Ken! (Nothing wrong with that molle experiment but I like that recurve) Wish I could find a spot to flight shoot...I think my arrows would shatter to bits after hitting the ground from any distance here....
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Hey Ken Nice job and I like experimentin with mollies.Have you thought about recurving your levers a bit.You should give it a try and i think you'll be surprised with what they add.I think it gets that short limb workin a bit more and stores more energy and nullifys handshock from the long lever.Just a thought ;)
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thanks nate , i like em too
thanks randy , recurving levers is a whole nother experiment that rich has done . but worth playin with
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ok had a few minutes waiting on the turkey today so i cut three inches off each lever and retillered it to same weight same draw. included are pics with paint removed as i was tillering. took it out and shot it with the same arrows and got a four shot average of 151 yrds.
now the testing is done im gonna finish it , repaint and maybe some snake skins and give it away if i can find someone that wants it
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Ken,
With your flight tests only slightly improved, it seems like there is the possibility that the bow just needs a heavier arrow. If a heavier arrow doesn't get more distance, it's possible that the 150 (plus or minus) yard range just might be what the practical limits of 44# are when shooting fully fletched hunting type arrows. Still dont believe that 150 yards of cast from a 44# bow is anywhere near bad though, regardless. JMO
rich
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Is this a first come first serve? ;D
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absolutely , heres the bow finished painted black with bullsnake skins , 52 inches 45 lbs @ 28 , 151 yrds with broadheads , after all the work , stress and retillering it finished with around 3/4 inch of set . hope yall enjoyed this as much as me .
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Damned fine lookin bow there Ken, It's a looker and shoots well too!!!!
rich
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Nice experiment. Shortening the lever length and moving the working portion of the limbs outwards should realize an improvement in performance
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Bow turned out very nice.It has been great to follow along on your progress
Thanks for sharing
Leroy
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thanks Rich
thanks Marc
thanks Stoker .
forgot to mention this morn before i finished i did take some of the lever down in width and depth so it might warrent some more flight test to see if there was an improvement.
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Wow, Looks nice Ken! I'm partial to gopher/bull skins too ;D Even when they're not pink ;D
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I am anxious to see the new flight shooting results after removing mass from the outer limbs. They need to be as light as possible and still be able to do their jobs. Pretty bow all finished up. Kenneth
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thanks ntd , black under the skin really makes em stand out.
thanks little john , didnt get the chance to shoot it today