Primitive Archer
Main Discussion Area => Bows => Topic started by: Dustybaer on July 24, 2008, 07:26:23 am
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i was just asked this question on a german archery forum: what's the highest recorded speed of a selfbow, using 10gr/# arrows?
does anyone know? to my knowledge, the 200fps mark has not been crossed yet. is that correct?
thanks in advance folks
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Marius, I believe Marc St Louis has come close to the 200fps mark but not quite there but in the 190s.
Pat
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I'm sure someone has crossed that barrier...somewhere. In TBB IV, Tim Baker says that with 10gr/# arrows, the average arrow speed for a well made selfbow is 100fps plus the draw weight of the bow. So a 110lb selfbow, for example, should be able to cross that barrier. (100+110=210fps)
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I'm sorry, Jim Hamm made the observation...bottom of page 109, TBB IV.
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"In TTB IV, Tim Baker says that with 10gr/# arrows, the average arrow speed for a well made selfbow is 100fps plus the draw weight of the bow. So a 110lb selfbow, for example, should be able to cross that barrier. (100+110=210fps)"
I don't have vol IV, but this is a common misconception. At least, one I harbored for while, in fact I picked up from misunderstanding Tim Baker's chapter in Vol I, until some flight shooter set me straight. If you hold the constant 10 grains of arrow mass for each pound of draw weight you normalize, or standardize the various draw weights. So, regardless of whether you shoot a 500 grain arrow from a 50# bow or 700 from a 70# the fps would be comparable, the same.
Edited: Evidently Jim and I had the same misconception of Vol I. I'm in good company!
170s is the best I've ever done with an r/d backed bow. As I understand it 180s is good, been done. 190s will get you a flight record, when configured for flight. Shooting technique makes a HUGE difference, 10 fps or more. Only way to really measure and compare objectively is with a shooting machine setup.
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I was reading that too from hamm. I have played with 3 osage selfbows, and it seems 150fps is all I can muster with 9gr/#. I bet hamm is heat treating, and back setting and the whole nine yards.
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I actually do a lot of testing using a shooting machine for more accurate readings. Obviously I have tested more of my own bows than anyone elses because I have better access to them. Shooting bamboo backed bows and using modern fast flight strings I have crossed the 190 barrier several times in the past year, I rarely get a self bow past 182 but had a best of 184 using a dacron string, if this same bow had been using a 6 strand fast flight it likely would have hit the 190 mark. We have an annual contest called " walk the talk". This contest is open to modern and primitive bows and all are shot using the same strings and identical 10 grains per pound arrows. The fastest modern bow hit 198. My bow had an official contest speed of 185 but was corrected to 188 because of tape that was used on the string to tighten up the arrow nock making it too tight. Using smaller lighter strings the fastest modern bow hit 202 and my boo baked bow hit 192 fps, I think it is safe to say that any self bow over 170 is considered fast and any backed bow over 180 could be considered fast.
Using 500 grain arrows I have hit the 200 mark with a 57# boo backed osage and a 61# maple self bow. I would imagine several guys would be getting similar numbers if they tested more often. Steve
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steve, if it's OK with you, i'd like to quote some of your statements (mainly cause i said earlier this morning that you and marc routinely make selfbows, shooting at 180-190fps.)
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Dusty, I wouldn't say that my self bows routinely hit 180, I have to struggle to hit 180 with a self bow. The backed bows do routinely. Steve
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that's exactly why i wanted to quote you. to correct my erroneous statement.
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I dont use the 10# rule, I use a 500grain arrow. My fastest was the 3/4" wide Ipe selfbow at 191fps. Justin
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The 100fps plus the bow weight was for shooting a 500 grain arrow- no matter what the weight.
Marc St. Louis's heate tempered reflexed static recurves shoot 180+ fps (with a 10 gpp arrow) but require alot of time and care. He wrote a great article on making one in one of the back issues of PA. His bows are selfbows, but not straight bows.
I believe Steve's bows, because of the care and work he puts into them, are some of the fastest straight or reflexed bows (non recurved). Even Tim Baker's Adamann-Homegard (sp?) design only shot about 175 fps with a 10 gpp arrow.
In TBB vol 3 there is a photo of Simon (sp? I don't recall his last name) shooting a hickory backed yew warbow, something like 150#, 208 fps with a 950 or so grain arrow.
You can easily break the 200 mark with a selfbow if you use the right design and a lighter arrow, to a point.
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My gosh, you guys got to be kidding me. 190fps-200fps regulary with 10gr/#. That can be tough for lam/glass bows.
I would love to see one. Very impressive.
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My gosh, you guys got to be kidding me. 190fps-200fps regulary with 10gr/#. That can be tough for lam/glass bows.
I would love to see one. Very impressive.
Wouldn't call it regularly, but yes you are right. A wood bow can be every bit as good as a lam/glass bow.
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Robustus is getting excellent speed out of his all natural horse bows. One he was shooting last year at Hickory would spit a light carbon arrow almost 280fps and a 600gr cane hunting arrow was bumping 190.
Pat
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My gosh, you guys got to be kidding me. 190fps-200fps regulary with 10gr/#. That can be tough for lam/glass bows.
I would love to see one. Very impressive.
Well life is not that easy, thats why I am building selfbows.
K-H
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and to heat up tempers a little bit i awarded a prize of a bottle of finest glenfarclas for the worthy winner ;D
but i think only few do have a real chance to be drinking it (and all of those will share a dram with me ::)).
´tiller then
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Thanks Mimms for saying that, I've being cringing at the whatever plus the bow weigth with 10gr per pound thing for awile now, just didn't want to mention it.
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@Badger, can you give a description of you shooting machine?
I'm interested in one for myself for testing my bows. With ~500gr arrow I hit the 190 with my BBO and it would be interesting to have more reliable ??? testconditions.
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Not to stir the pot but wasn't it the emphasis on speed that led the developement of compounds?
Ok maybe I did stir the pot ;) I respect everyones right to pursue their own goals in bow building
and one should strive to make a well designed efficient bow. If speed is your goal great, but for some of us
a good durable bow that shoots smooth with suffienct power to hunt with is all we need :)
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Very interesting stuff and I do try to make them as efficient as I can but I guess I am with Dana.
Speed ant my main objective. It is cool for those that want to pursue it and show that a self bow can stand up proud with backed bow and even a lot of glass bows with about the same arrow
weight.Reading this stuff has given me some good ideas over the years on how with out to much extra figuring and work to make a more efficient selfbow.Thanks for that.I guess I go by the 100 +
draw weight and am satisfied with that.Good thread. :) If it will get into a deers lungs then I am
happy with it. ;) :)
Pappy
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Not to stir the pot but wasn't it the emphasis on speed that led the developement of compounds?
Ok maybe I did stir the pot ;)
Isn't that what you do for a job? ;)
Like Pappy said, its about getting efficient. And some like to get as close to efficient as possible. I have had several guys shoot my longbows and see how "fast" they are and say they will hunt with one. Before they always thought they would be slow so they refused to try one. If you can show them that a very efficient hunting bow can be made from wood and that plenty of speed can be had you might win over a few more. Besides, its not just about building the fastest bow. Sometimes it is about building the shortest bow that will pull to 28". I like to push myself, its how I improve. Justin
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See it as a game or a hunt for knowledge or something like this. Playground for old boys ;D.
But remember, as mankind tried to reach the moon, some archer try to reach the 200fps with a selfbos.
For me it does not mean, that I will shoot a selfbow of 200+ fps under any circumstances.
I will shoot the fastest of my bows, which I can handle properly ;D
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What about draw lenght? Do you all use a standardized length for these impressive numbers. My 25" draw length lets me achieve 100fps+ poundage on my bows but that's about it.
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That is where I am Eric. :) I don't know how much, but draw effects the speed and power a lot.
I shot with guys that draw 50@ 28 and I am shooting 50@25 and you can see the difference
and tell the difference when you pull the arrows from the target.I am been working on my form ,trying to get a little more and am up to about 26 and that will be about it for me. :)
Pappy
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Ya I think yer done growing Pappy ;) ;D
I'm in the same boat pull 26" on a good day :(
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It turns out with natural materials you can't achieve the big speed numbers without the other desirable stuff, like low shock, noise and longevity you want for a "hunting" bow. Once you exceed the elastic limits of the material the bow is in effect toting around limb mass which doesn't store energy. The wood is already crushed. Bad mojo for efficiency. On the other extreme, regardless of the context, if you leave too much wood working you have shock and noise. So, aside from ones that store lots of energy, like Marcs bows with 5" or more of net reflex or recurve, horn bows or horse bows, and even these one could argue, "fast" bows are not really a great deal different than a "hunting" bow. It's a misconception to assume folks who concentrate on speed aren't interested in the other attributes. Rather they tend to satisfy the fundamental stuff first, and then go after speed as well. At least that's what I do.
It's not a sin to go for speed, that's our purpose ultimately. I have a hard time understanding where people are coming from, not necessarily in this thread, who say it's not important or not "traditional" or whatever and seem to have a real chip on their shoulders about it sometimes. If I can have, and I think I can, a bow that is quiet, no handshock, lasts practically forever and fast I'll take it over quiet, no handshock, lasts forever and slow. Just seems logical to me.
Subject seems to come up no FastFlight versus Dacron threads a lot. Folks act like an extra 6, 7, 8 fps, all else being equal, doesn't matter. Seems like leaving perfectly good chicken on the bone to me, so to speak. Same with bowyering, chances are the 3, 4 fps left on the table can come off the outer limb width and the bow would never miss it, would not even change the tiller in a lot of cases. But I draw the line at tiny little out limbs, maybe 7/16" being about as little as I care to go. Dang things just look too fragile when you get down to 5/16". Another overlooked aspect is how you treat the wood during the construction process. By simply working the wood less, more carefully, I believe you can pick up 3, 4 fps in the finished bow, for the life of the bow, and that's leaving the design exactly the same. Then there is the more obvious stuff like moisture control, etc. It will sound like we're obsessing over insignificant things, but 3 or 4 fps scattered over 3 or 4 different opportunities and pretty soon you are talking 12 to 16 fps cumulative difference. That equates to 12# to 15# difference in draw weight, or 2" to 3" of draw length (having read Pappy's post). Not insignificant by my reckoning.
Maybe it's just a personality thing. If it goes, no matter if a pickup truck, lawn mower or a bow-n-arra, I want it to go faster, stronger, better! LOL
Eric folks use 6" brace, 28" draw generally, although the brace height is where some fudging is going on. In extreme cases, Tim Baker's bows at the first MoJam for example as I understand it, going down as low as 4". But I don't think that is necessarily typical.
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David I agree about low shock and noise going along with speed, but I think there is less correlation with longevity. I would contend that bows stressed to near the elastic limit are going to deteriorate more quickly. Being within 5% of the elastic limit, is going to change the wood faster than being within 10%. I think the flight bow people know this and act accordingly. I know that staying anywhere under the elastic limit ought to keep you safe, but all wood fatigues with use so that elastic limit is constantly shifting. The shift is dependent on the amount of use the bow gets, as well as the conditions it finds itself in. A hot humid day probably shifts that limit downward a bit, a mild dry day shifts it upward.
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My gosh, you guys got to be kidding me. 190fps-200fps regulary with 10gr/#. That can be tough for lam/glass bows.
I would love to see one. Very impressive.
Well life is not that easy, thats why I am building selfbows.
K-H
Hmm, not following you. This is basically a selfbow page. ???
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Not to stir the pot but wasn't it the emphasis on speed that led the developement of compounds?
Ok maybe I did stir the pot ;) I respect everyones right to pursue their own goals in bow building
and one should strive to make a well designed efficient bow. If speed is your goal great, but for some of us
a good durable bow that shoots smooth with suffienct power to hunt with is all we need :)
Yea but what about when your like me, and have bows shooting way slower than molassas? ;D
But my first osage I was worried about breaking, so I made the limbs 1.75" and made it 67" for a 55lb bow. Figured I didn't want my first breaking easy. I know thats alot of mass and overkill.
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We all done that,at least most,but as time goes on and your confidants grows you start to
push the limits some,mine still aren't what you would call fast but a lot better than the first ones.
Like justin said it is just a way to push yourself to get better and learn more, that is what most want to do.Threads like this helps that.Thats why I love this site you learn just by listening. :) and then take what you like and leave what you don't and move forward. :)
Pappy
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Yup Pappy we all learn from each other :)
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I wish I had the tillering eyes that a lot of you guys have here. I think I could pick up a few fps more LOL. I don't see chaseing speed as any different than any other aspect of any hobby, we all just take different directions. One thing that in retrospect I find interesting is that as incremental plateaus of performance arre reached it is comparable to opening doors and walking through them. Makes you feel like you have gone deeper into this world of bending wood. Almost like focusing a microscope but instead of using vision your microscope becomes your understanding of things that formerly had no meaning. An individual with good tillering skills can easily replicate a high performance bow and make it very very fast, having a lot of knowledge isn't really neccessary once the recipe has been figured out. I have seen several examples of bowyers with extraordinary bowyering skills with relatively little knowledge of the dynamics, the result was still an extraordinary bow by following simple design principles. As we get closer to the 200 fps with 10 grains barrier all the facets that make for efficient fast bows have to come together in unison. Low hysterisis, high energy storage, low vibration. We used to say a fast bow is 90% broke. I would change that today and say that a fast bow has not even entered the point where the wood has started to take any set or deform at all yet, well inside it's limits of not breaking. Someone named Hickman year ago made the statement that if a bow limb were rigid and had a hinge right at the handle it would be 100% efficient regardless of limb mass, he was right! If a bow limb did not distort it would return all the energy to the arrow before the string slammed tight. The distorsion is usually midlimb and starts several inches before the string slams home in the form of a forward bulge. Stiffening the limb through designs, removing some of the limbs mid outer limb mass also lowers the momentum it has that exagerates this bulge. Lighter weight outer limbs not only accelerate faster but also allow the arrow to more effectively slow them down as the leverage changes at the end of the stroke making the arrow effectively much heavier. Very fast bows don't slam home as hard as slower bows, the arrow is able to soften the landing and sap out the energy the limbs have stored more effectively. You really don't have to make bows skimpy and fragile to be fast. Steve
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We all done that,at least most,but as time goes on and your confidants grows you start to
push the limits some,mine still aren't what you would call fast but a lot better than the first ones.
Like justin said it is just a way to push yourself to get better and learn more, that is what most want to do.Threads like this helps that.Thats why I love this site you learn just by listening. :) and then take what you like and leave what you don't and move forward. :)
Pappy
What are the tricks for speed? I figured it would be limbs as narrow as possible. Heat treatin the belly. Recurving the tips. Generally overall design and shape.
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bigcountry a good place to start is with Badgers mass theory formula, Steve perhaps you can post the Excel spreadsheet again.
I agree we all build bows for our own reasons but I can be happy with a decent hunting bow that shoots fair as I advance in my skills I may very well
start experimenting with different designs and tillers to increase performance but its not necessary in order to enjoy this wonderful addiction we all have.
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Lennie I concede your point. It's a spectrum, not a hard line in the sand.
Not sure you have followed a couple of the things learned, or relearned in the flight shooter discussions lately, in the last year or so. I'll try to give the Reader's digest version. First, I did not really appretiate that a good portion, perhaps most of, the KE in the bow is transferred to the arrow in the last few inches of power stroke. Second, bow limbs do not retain the same shape on the power stroke as they do on the draw stroke. This difference accounts for a good measure of the lost (to the arrow) energy in the system. Steve is talking about these things in his last post. Using enough wood, when done with considered design, actually works in one's favor in terms of making maximum cast. Flight bows don't necessarily have to be right on the edge of broken, so close to the elastic limits, if you can apply the first two principles with good design. It's still all about a) store lots of energy and b) get as much back out as possible, in various combinations.
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We all done that,at least most,but as time goes on and your confidants grows you start to
push the limits some,mine still aren't what you would call fast but a lot better than the first ones.
Like justin said it is just a way to push yourself to get better and learn more, that is what most want to do.Threads like this helps that.Thats why I love this site you learn just by listening. :) and then take what you like and leave what you don't and move forward. :)
Pappy
What are the tricks for speed? I figured it would be limbs as narrow as possible. Heat treatin the belly. Recurving the tips. Generally overall design and shape.
I don't think there are any "tricks." Those things do help, depending on the design. Like Steve said, a well tillered bow is usually quite efficient. If you want to increase performance I suggest you at least try Steve's mass formula. It will help you to not build it to wide or too narrow. I for one break as many bows as I finish. Why? Because I like to push the wood and my skills. I figure a bow that is on the verge of breaking will show me my weakness, not the woods. It will not forgive tiller that is slightly out or a flaw in design or workmanship. And the best part....... I can build another which is what I really want to do anyway. ;D Justin
I see Dana suggested Badgers formula while I was typing. ;)
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Big country, one of the beauties of this bow making thing is that several different designs can yield very similar results, for non reflex desings, elbs, holmgardes, piramids, and a million variations of these can produce very similar results. Number one most important thing for performance is dry wood!! You simply don't stand a chance with out it. I don't worry about it much on my everyday bows and just settle for whatever they come out as my moisture is just a little on the high side and still acceptable to me. I tend to favor the woods with higher oil content that seem less sensitive to moisture issues.
I think the other important thing is moderation in design, nothing too fancy, the more curves you put in a bow the wider you need to make the limb and the wider you make the limb the more it will vibrate and flop around. I had a guy build me a modern longbow this year for the flight shoots, he incorparated a lot of the simple tecniques we use on wood bows and the bow looks like it set a new speed record for modern bows hitting 202 fps with a 10 grain arrow at 28". he used a moderate r/d design with less than 2" net reflex.
I think another thing that is important, instead of glueing in 4" reflex to finish with 1", try glueing in 2" reflex and finishing with 1 1/2. The wood is a lot stiffer when it hasn't been damged so much, has less hystresis, higher early draw weight and stacks less. If you are tillering a bow out and it starts to show sings of loosing it's reflex at say 24" it will likley be a fast bow at 24" but not get much faster as the draw length increases unless you can get more wood involved in the bending process and stop the set from increasing. I try to start my bend in the mid inner limb area and as needed I work toward the handle and out toward the tip. I use a method of monitoring the wood that doesn't involve measuring the set. I use a bench mark of say 20" or whatever and check the draw weight there, as I draw the bow out further I keep going back to my bench marl to check and see if it has lost any weight. Every time I remove wood I have to establish a new benchmark. This is realy effective as the wood will actually start to drop in weight before you can visually see the set happening.
I am not really sure about the next statement I am going to make but I suspect that when there is a radical transition in the shape of the bow both in width and thickness it seem to interupt the harmonics somehow and lesson the distorsion or vibration on the return stroke. A holmegarde would be an example of this, I use a modified version of this on my outer limbs in the r/d designs. Steve
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Steve,
I have never seen a picture of any of your bows. Do you mind posting-up a front profile shot so I can see what your talking about? I'm about to embark on a BBI and I'd like to give it a try.
Cheers,
Grant
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I've been making modern glass bows since the early 90's. It wasn't until I recently started making wood bows, including self bows and backed wooden bows, that I started learning how to make an efficient bow. Most of what I learn about good bow design comes from here and yuku. Don't be afraid to pat yourself on the back. I think most paleo bowyers are more concerned with efficiency than some of them are willing to admit. I'll be the first to say that most glass bowyers don't know how to make an efficient bow, whereas most experienced wood bowyers do. Overbuilding your bow so it won't fail is a choice just like underbuilding one to limits of elasticity and mass. I have always been a student of efficiency. Form follows function. Most of what I've learned about efficiency came from Badger and Tim Baker... I'm currently building their theories and having great improvements in performance and handling. In my opinion, their modified holmies are the most efficient designs. Look at any of the best bows and they have similar characteristics. Lately, I've been watching bows as they are shot to see the power stroke. The most efficient bows have very little limb movement during the draw and are equally stressed at every point along the limb. You can barely see any single point moving more than another... and when the limbs return to brace, there is no visible deformation or vibration, they simply return home and stay put. Watching someone else shoot my bows makes it easier to see.
I've found this essay by Dennis LaVarenne to be very useful, especially the limb profile on page three...
www.fiarc.org/public/Forum/Data/jeval/2005102714414_Tillering%20the%20Holmegaard%20Bow-2.pdf
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You can see one Steve's classic bows on the bowyer's journal site. His laminated entry for the ambush bow contest is a perfect example of his theories. The bow is also incredibly short and narrow for the lengthy draw it withstands. I want it :)
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You can see one Steve's classic bows on the bowyer's journal site. His laminated entry for the ambush bow contest is a perfect example of his theories. The bow is also incredibly short and narrow for the lengthy draw it withstands. I want it :)
Ahh I see that bow now. I sure wish they had a unbraced shot. It almost looks like it doesn't have a very typical Holmie front-section but it does have a typical holmie tiller. How wide were the bending limbs on that one and how did it go through the chrono?
It's amazing what that Ipe will stand, it's damn near one of those Hickman bows.
Cheers,
Grant
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Well according to Steve the bow had minimal reflex at glue-up and settled at straight after shooting. He does also mention his working limb was a tad wider than normal at one inch (!!!). It makes you think you could tip-toe up the inner limb width and max out that hinge theory even more.
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Thats pretty much what I'm thinking about. Trap the boo on the working parts to keep it from overpowering the Ipe and then trap the Ipe on the outers to keep weight down while still having enough width for stability. I'm thinking along the lines of an extremely stretched and exagerated Holmegaard. Probably glue it up straight just to keep from having stability problems.
Ahh efficiency is probably one of my favorite things to think about in all my past-times, why should bows be any different.
Cheers,
Grant
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When quoting speeds you should also quantify the numbers. I have been able to get more than 240 fps with a wood and sinew recurve but that was using 300 grain arrows in a 70# bow. I have made many bows that shot 180+ using 10GPP arrows and only a couple that have gone over 190 fps with 10 GPP arrows. For the last few years I haven't bothered chronographing my bows. I know they are fast. They are also smooth and excellent shooters, at least that is what I am told :).
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Mark, I have tested your bows after they had been shot for a couple of years at drasticaly overdrawn lengths (31") and they still tested out very fast. I believe your selfbow recurves are faster than the self bow straighter bows. The backed bows seem to hit the same wall weather they are recurved or r/d from what I have seen. Low 190's seems to be about the limit. I know I am done chaseing it.
Pat, my ambush bow was much wider than 1", I think closer to at least 1 1/2" wide. I still shoot the bow quite a bit. It must have been a misprint. Unless a bow is bend through the handle I seldom go below 1 3/8 on even the densest woods anymore.
Just for the record, I play a lot with chasing speed but my primary interest in bow making is basicaly just selfbows. I like them to feel snappy but seldom test them for speed unless I think they might be a candidate for flight shooting or something. I used to test everything but have gotten away from that this last year.
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guys i belive mark st lousis has made the fastes one out there bob barnes sent me some pic s of the WHITE LIGHTNING bow it s elm also if i rember correctly bob told me at mojam last week that they have a pic of it being shot next to the cronograph doin 196 or somthin like that maybe we can get mark or bob to tell us and post a pic of it BROCK
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Brock
The second White Lightning bow that I sent Bob was HHB and it is the one that shot into the 190's. Glad to hear it is still shooting.
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We all done that,at least most,but as time goes on and your confidants grows you start to
push the limits some,mine still aren't what you would call fast but a lot better than the first ones.
Like justin said it is just a way to push yourself to get better and learn more, that is what most want to do.Threads like this helps that.Thats why I love this site you learn just by listening. :) and then take what you like and leave what you don't and move forward. :)
Pappy
What are the tricks for speed? I figured it would be limbs as narrow as possible. Heat treatin the belly. Recurving the tips. Generally overall design and shape.
I think a Holmagaard would be what you would look for or an exagerated andaman design for a very fast selfbow then.
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We have an annual contest called " walk the talk". This contest is open to modern and primitive bows and all are shot using the same strings and identical 10 grains per pound arrows.
steve, where can i look up the rules for the "walk the talk" contest? is that the one at MOJAM? if not, does anybody know the rules for the MOJAM speedtest?
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Do we have a picture from this bow?
K-H
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A picture would be really nice!
If someone has it, please post it.
@D.Tiller: I agree with you,I would prefer the Holmegaard design as well.
But witch tillershape would you prefer the "normal" one or the one Dennis LaVarenne introduces in his essay?
Thanks, Acker
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Well, It's hard to say without seeing them myself. I have a feeling that if you get the same amount of wood working and same static area you should get aprox. the same velocity to the arrow. Would like to see them in person sometime. Those large backs do make for a great pallet for putting artwork on!
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Have any of you guys got any crono results at 5grns per#??
David
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I have tested quite a few at 5 grains per pound. I consider anything around 230 fps real good. I have one now that will hit 240 fps. I have tested lighter than 5 grains a pound and gotten over 260 but the bow expoded on the first shot. Funny thing about getting the speed out of the arrow is that it is not always easy to get good flight, if an arrow takes off a little sideways it's velocity will fall off very quickly.
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I was asking becuss I took 2 lams of Ipe and glued a piece of purplehart in between them and then cut strips out of it and barel tapered them down for flight arrows and turned the purplehart horizantle to give me the spine I needed. They shoot clean off my 55#@26 bow but they are only like 6grns per #..Any thoughts??
David
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I have calculated that we need 40 % more stored energy than the "straight" line. My problem is that the bulge comes to quick down, therefore I loose 5%. But the recurve that prevents that is very difficult to make.
I still belive it is possible, but apart from the design, the technical skill to build this is very high and last but not least.... who has the perfect piece of wood.
K-H
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This is a picture of a 190fps recurve I built several years ago. This bow shot 190+ fps with 10 gpp arrows. The bow was a heat treated HHB static recurve that I built for Bob Barnes
[attachment deleted by admin]
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I believe I handled that bow at a Mojam. Nice bow, impressive. and inspiring. Not a speck of extra material on the outer limbs and recurves. Very nice fit an finish. Might have been the only bow of yours I've actually handled Marc. Didn't realize at the time it was one of your top performers, but not surprised in hindsight.
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She is looking fine, that seams very similar to my proposal. May I ask the draweight and drawlength. I think the last 10 fps ist the job for the "working" recurves.
K-H
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Karl, what speed are you trying to reach at what arrow weight per pound. We now know for certain that 200 fps is possible. Looking at Marks bow it is very similar to a longbow but has the static recurves. I think maintaining high efficiency is more important than looking for more energy storage for optimum speed. Both Longbows and recurves have crossed the 190 mark. Steve
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Actually David the recurves could stand to lose a bit of useless bulk.
I don't remember exactly what the draw weight was but it was about 55#. The bow was tillered to 27"
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"Actually David the recurves could stand to lose a bit of useless bulk."
LOL. I suppose it's a matter of perspective. I don't disagree. I just lack the cojones I reckon.
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We now know for certain that 200 fps is possible.
lol Why has no one a 200 fps bow with 10grain/lb ? 190 is not 200, it is more or less like the sonic barrier, close is not through.
K-H
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Karl, myself and a few other guys I know of have actually hit 194 fps, I know from experience that if I were to have lightened the string, loosened the arrow nock and cleaned up the arrow shelf I could have squeaked out 198 fps. Thats close enough to tell me it's possible. Modern longbows are now hitting 200 fps, recurves have just scratched above 192 I believe. One gentleman with recurves has reported a 200 fps but the bow broke before it could be verified.
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I know from experience that if I were to have lightened the string
3 grain stringweight / lb !!
Regards
K-H
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Steve, are you going to the flight shoot this year? What are the dates? Justin
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Justin, I won't be able to make it this year it looks. The dates are going to be weekend of sept 8th, Just a long shot I might be able to swing it but I doubt it. Steve
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We now know for certain that 200 fps is possible.
lol Why has no one a 200 fps bow with 10grain/lb ? 190 is not 200, it is more or less like the sonic barrier, close is not through.
How about now? Still no 200 fps with 10gr/lb selfbow?
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As far as I know no one has surpassed it yet. Only a few modern bows using carbon fiber and skinny fast flite strings have surpassed it. If anyone ever does surpass it it would be questionable and need to be verified very carefully. I still think it is possible if everything came together. Some work I did on no set tillering a few years ago does imply that wood can be nearly as efficient as fiberglass or even carbon fiber before it starts to break down. If best designs were used with best woods and flawless tillering it might happen.
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I made a 39# @27 " static recurve from Osage that got me a lil over 160 fps with a 550 grain arrow, surprised me and the certified archery instructor who let me use his chrono, I dint have any lighter arrows at the time..would have been interesting to see with a lite arrow.
I have got 160's from 48" sinew backed osage bows many times.
The best I've ever got was 206 fps with a Korean composit bow with a carbon arrow..but never a self bow.
E
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I made a modern holmegaarde style from black locust, very light heat treatment after tillering, for my best friend who took it to a range and her first classes and wowed the instructor and pros with its speed. No numbers as of yet, I know it's 35#@26", but ill have to get fps next time I'm up her way.
I'm curious to hear what Blackhawk has achieved with his mollegabets.
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Love that speed- topic forever!
I` ve experienced short bows shot with light arrows to be the highlights in this case.
For to match the 10GPP- challenge just scale down like Woodbear has stated it in the PALEOPLANET: " Being a guy with 25" draw, I find that bow 10gpp performance with a standard 28" draw, does not really tell me what performance a particular design will give me at 25", it always requires some translation. The translation comes in the form of the modified formula. The formula does not simply divide 10gpp by 28". I scale the 10gpp rule by the ratio of my draw to the standard 28" draw. So I expect that my 25" draw bow with a 10x25/28 = 8.9gpp arrow will give the same speed as a same design 28" draw bow with a 10gpp arrow.
For example, a 54" long, 43# at 25" bow will be tested with 10x25/28 = 8.9gpp arrow (383 grain arrow), and should give the same arrow speed as an "equivalent" design 62.6" long, 43# at 28" bow at 10gpp (430grain arrow). This will give a good idea of how a small version of a design will perform if enlarged to standard draw.
I hope this clarifies the rationale and use of the modified grains per pound guide line."
Or here: "Arrow weight is 280grs., drawweight is 40= 7gpp. For comparison with a 28" draw I would need 10x 23/28= 8.21gpp. So I had to use a 328grs. arrow? 328/40=8.2?"
The topic is here: http://paleoplanet69529.yuku.com/topic/55268/10-grains-per-pound?page=1
So there is much more space for experiments!
I guess a lot of selfbowyers are trying to break the 200f/s, this is at least a great guideline to increase performance.
But the weakest spot seem to bemuch more the arrow than the bow.
I`ve recently succeded in making barrelled wooden shafts( 23" in length, max. thickness is 7mm or about 1/8", 283grs.) with a deflection of 0.45 - 0.59( 100+ lbs spine), but have not yet shooting them.
Michael
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Hi redhawk. Good to see you. Glad you brought the link in. I get frustrated with the 10gpp view when folks dont account for draw length. Woodbear came up with a brilliant solution for that.