Primitive Archer
Main Discussion Area => Bows => Topic started by: DC on May 11, 2018, 05:03:21 pm
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I had a pair of sister billets that were pretty much flawless except they had a pronounced sideways bend. It occurred to me that if I made the bow edge grained the sideways bend would be reflex. So this is an all edge grained Hard Maple backed Yew, Backing is about .140. 40#@28" 62" NTN measured as the crow flies, 64" following the curves, 1 3/16" wide tapering to 7/16" tips, 4" handle, 2" each fade. I glued in a bit of Perry reflex but it didn't hold well. The tips are about dead even with the handle. Normally I get increasing reflex when I tiller bows with Perry reflex but this one didn't. it seemed to take some set right from the start but then stopped. I'm assuming it was just what I glued in pulling out. I wasn't expecting too much but I got my PB at 192fps at 10 gpp. I was pumped, still am actually. I'm wondering if Bamboo backed would be better.
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Very cool bow that's my favorite one you have posted, awsome bow awsome numbers innovative thinking on that one :OK
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You're on a roll my friend! That's a beauty, and those numbers must be satisfying indeed! Awesome 8)
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DC, Edge grain is super strong...Good thinking outside the box on that build...Your bend is really nice...
Don
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Very nice lines to that bow of yours.You're getting this design really dialed in.Congrats.
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+1 for very cool bow.
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:OK
Don I had some good luck with edge grain maple used as a backing.
Is your maple edge grained, or your yew? or both?
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lovely bow!!
My favourite of the maple bows I made was edge grained.
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The maple is edge grained too.
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Very nice bud. Don’t you love those small stout recurves? More working limb but you still get that string angle
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Dc when you get there could you please post your shot in numbers 300-400 arrows also was that speed from the shooting machine or finger release ?
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Thanks for all the comments guys, 'preciate it.
SB, that 192 was with a 400 grain arrow, I'll try some lighter ones. That's using the shooting machine. Since I built the machine I haven't shot through the chrono manually. The machine is very consistent. I have only had one time where I had a variance of 1 fps. Every other time it just repeats the same number over and over. With a finger release the numbers would vary by 10-15 fps or more. The machine gives me way more confidence in my results.
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I was just curious I have a friend that builds glass bows that says he gets 3 -8 fps difference between finger release & machine I was just curious what the difference with a wood bow average to average !
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In my case it's just a matter of me having a crummy release. I would think that a 3-4 fps difference with a finger release is pretty good, I know I'd love to be able to do it. Makes me wonder how consistent a real good shot would be ?
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That bow there DC will kill any big game animal in the USA consistently at 20 yards and more if you can put it in the 10 ring at that range with a 600 grain arrow.I'll gaurantee it.With the ease of shooting a 40# bow too yet.
Good build buddy.Something everyone should take note of here too.
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I don't test anywhere near as often as I used to but when I am testing regularly I can pretty much match the machine and stay within 1 or 2 fps. Most regular hunters I know shoot about 7 fps or more below machine speeds. Shooting by hand can also pump up a reading by using a well timed forward movement of the left hand. You can add up to 10 or more fps to a shot. Lately I have been testing by hand, I fixed my machine recently so I will see how close I shoot to it.
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I tried a 348 grain and got 202 fps, arrow broke on the first shot.
I tried a 298 grain and got 215 and 212 and the arrow broke on the second shot.
I don't want to do any more, arrows are too much work ;D ;D ;D
Ed, the heaviest arrow I have is a 557 grain. I got 169 fps. Boy, the weight sure slows them down.
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I don't test anywhere near as often as I used to but when I am testing regularly I can pretty much match the machine and stay within 1 or 2 fps.
I'd kill to be able to do that ;D. After 70 years I've pretty much reconciled myself to having very poor hand eye coordination. I've always been able to build things but I've never been good at sporty stuff. I think the technical term is klutz. That's why this machine is the answer for me.
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Very nice bow DC. That's thinking out of the box for sure. Those are some pretty impressive numbers. Those heavy arrows might not start out as fast but in a short distance they they keep moving longer on the other end of their flight.
Bjrogg
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That’s a sweet bow DC. 170 FPS with that weight arrow and only 40 lbs is great. Best of both worlds. Hunting arrow, great speed, and only a 40 lb bow.
I haven’t tried yew yet, but that seems like an excellent combo you got there. The one maple backed bow I built was actually faster than my bamboo bows, but it exploded after around 100 shots.
I love the shape of the bow too with the deflex and recurves. I think you have found an excellent design. Great job
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I just copied Marc St Louis, to give credit where credit is due. :) :)
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DC, I did some calculations on your bow based on the numbers you supplied. This bow has a virtual mass of something like 70 grains and shows no losses to hysteresis. You could expect to get about 250 fps from a 200 grain arrow which could put you well into the 400 yard range, maybe 450 yards. I would be tempted to shoot that in the 35# classes and just draw it maybe 24" using a 22" arrow. Lots of potential.
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550 grain 170 fps 40 lb would be a awsome dear or elk bow 👍🏻👍🏻
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I like the combo with yew and maple. Pretty bow and great speed. Like Steve said I would try that for flight just to what that it can do, lots of potential with those arrow speeds.
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Very cool bow!
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Thanks guys. Just to make myself happy I mounted my second Chrono to the shooting machine and got the same results within a couple of fps. Flight shooting around here is tough, there is no open spaces. We managed once in the last year.
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DC, can you do a force draw in it if you have time?
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DC...I figured a 600 grainer would go around 160 fps.So it's right in there.
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DC, can you do a force draw in it if you have time?
It was on my list before company dropped in. They're gone now
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Not that impressive I don't think. I have a stop on the scale I use for this and if I'm not really careful I can overshoot the weight on each step. I think that accounts for the 1 and 3 at 20 and 21. Gotta think of another way. OK I fixed it
8"=2.5
9"=5
10"=8
11=11
12=13
13=15
14=17
15=19
16=20
17=22
18=23.5
19=25
20=26.5
21=28
22=29.5
23=31
24=33
25=35
26=36.5
27=39
28=41
It basically goes 3# steps to 11", then 2# steps to 18 and then 1.5# steps until I guess it starts stack at 27-28. Does that qualify as early draw weight.
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The performance numbers are too good for that force draw. I would double check the calibration on your scale.
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I'll double check all my scales. I've already done my arrow scale. When I made my spiner I weighed the 2# weight with certified scales. I'll have to be more creative for my bow scales but I've been through this more than once and they've always checked out. Can you think of anything it might be other than the scales?
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Very impressive and beautiful design!if your breaking arrows I would wear a leather glove! I found this out the hard way by impaling my thumb!
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Lovely bow and excellent performance.
Most of the time I will reflex the limbs with dry heat before I glue the backing down, if it's a type of wood that reacts well to heat that is, and then add more reflex on glue-up. The bow keeps much more reflex that way. If the wood benefits greatly from heat-treating then I do that as well as I am reflexing it.
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Thank you very much. I was shooting the arrows on the shooting machine so impaling my hand wasn't an issue. They were breaking when they hit the target. The only light arrows I had were to low in spine.
The bow already had about 2" of natural reflex. I was a little hesitant to put in much more as it was my first Maple backed Yew and I had a few worries about the backing. I did make a similar Boo backed Yew a while back and I heat treated the belly with good results.
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Very nice bow! Looks like a smooth shooter. Great job!
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The performance numbers are too good for that force draw. I would double check the calibration on your scale.
We have a pretty good bathroom scale so I put a 5 gal bucket on it, zeroed it out and poured water in it until it weighed 40#. Then I lifted the bucket and water with my bow scale and it said 40#. Then I got out my go to garage scales that are accurate to +- 1 gram. They will only weigh up to 5# so I scooped water out of the bucket and weighed each scoop until I ran out of water and then I weighed the bucket. I got 40.19#. So I'm confident in my scales. I realised that as I pull on the scale it gets longer(the spring stretches) and at 40#it is a half inch longer. I made a new peg board and put each hole 1.025" apart instead of 1" to compensate for this.
I redid the FD chart and it varied a pound here and there from the chart I posted.
So I've checked my scales bow and arrow and made a new rack for doing FD on. I've actually done three FD charts with slight mods each time and each time the numbers didn't change enough to bother changing anything. It's a very linear 2# per inch. Just to make sure the bow hasn't gone away I shot two through the chrono 400 grains and 40#@28" and got 190.7 and 190.8 fps. I'm going to move the shooting machine outside and take a couple of shots to eliminate lighting as an issue.
My setup.
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It sounds like you are doing everything right. I have no doubt you have a super performer there. I would sure like to try that thing out on the flight range. If you happen to have a very light arrow ( in the 200's) you would like to shoot through the chrono that would ne interesting. Your virtual mass is incredibly low and it should really zing those light arrows. If your stored energy were just a bit higher I would feel better. Always the risk of breaking a bow shooting light arrows so if you don't care to take the risk I wouldn't blame you. I have never damaged a bow doing it but I have seen a few of them come a part at the range
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I just can't get enough spine in a 200 grain arrow. Even 300 grain ones break when they hit the target. Maybe on a 24" arrow.
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That would be cool. If you can use an arrow you don't care much about. You don't even need feathers or tip, maybe darken the end with a marker
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I just hunted through all my carbon and aluminium arrows and I can't get anywhere near 200. I got one 28"carbon that was 288 grains. That went 205fps but even if I cut that to 24 inches it would be 222 with no tip. I'll keep poking around.
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I just copied Marc St Louis, to give credit where credit is due. :) :)
DC, there is lots of good inspiration around here, but a nice execution of any design that comes out that good, needs some credit given to the bowyer.
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The Mark St Louis design is so unique that even if it catches on and a lot of others start using it or variations of it. I believe it will always be known as his design. Minute improvements to it might be made over time but I doubt they will amount to much.
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I did a little messing around with a piece of bamboo for a test bow. I had noticed that the "lever" of a bows limb gets shorter as it bends because the length of a lever is measured in a straight line from point of effort to the fulcrum. So I bent the bamboo to "brace" height and measured the lever length. Then I bent it to full draw and did the same. As you can imagine the lever got shorter. Then I bent the "limb" into reflex and deflexed it at the handle. When I bent the limb the first part
of the stroke was straightening it so the lever got longer and then it started getting shorter but the net result was that the lever wasn't as short at full draw. I think the deflexed handle helps because it delays or reduces the bend at full draw. This gives more leverage at full draw. When I start thinking about how this affects energy storage my brain kind of rebels on me. The lever length only changes by a few percent but it's a good few percent. Lots of people probably know this but I thought it was interesting.
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Good observation. Every part of a limb is responding to it's own relative string angle. The more of a limb you have at a low angle the better leverage your arrow has to suck out energy.
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I did a little messing around with a piece of bamboo for a test bow. I had noticed that the "lever" of a bows limb gets shorter as it bends because the length of a lever is measured in a straight line from point of effort to the fulcrum. So I bent the bamboo to "brace" height and measured the lever length. Then I bent it to full draw and did the same. As you can imagine the lever got shorter. Then I bent the "limb" into reflex and deflexed it at the handle. When I bent the limb the first part
of the stroke was straightening it so the lever got longer and then it started getting shorter but the net result was that the lever wasn't as short at full draw. I think the deflexed handle helps because it delays or reduces the bend at full draw. This gives more leverage at full draw. When I start thinking about how this affects energy storage my brain kind of rebels on me. The lever length only changes by a few percent but it's a good few percent. Lots of people probably know this but I thought it was interesting.
That works well when its bent without a string. With a string, it cant get longer, that means that because it wants too, its forced to bend further than it otherwise would per inch of draw, storing more energy in that draw inch than otherwise would have been. Its really a damn good design feature, and one I have used in my last two short bows. I am trying to figure how to make the most of that.
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I did a little messing around with a piece of bamboo for a test bow. I had noticed that the "lever" of a bows limb gets shorter as it bends because the length of a lever is measured in a straight line from point of effort to the fulcrum. So I bent the bamboo to "brace" height and measured the lever length. Then I bent it to full draw and did the same. As you can imagine the lever got shorter. Then I bent the "limb" into reflex and deflexed it at the handle. When I bent the limb the first part
of the stroke was straightening it so the lever got longer and then it started getting shorter but the net result was that the lever wasn't as short at full draw. I think the deflexed handle helps because it delays or reduces the bend at full draw. This gives more leverage at full draw. When I start thinking about how this affects energy storage my brain kind of rebels on me. The lever length only changes by a few percent but it's a good few percent. Lots of people probably know this but I thought it was interesting.
That works well when its bent without a string. With a string, it cant get longer, that means that because it wants too, its forced to bend further than it otherwise would per inch of draw, storing more energy in that draw inch than otherwise would have been. Its really a damn good design feature, and one I have used in my last two short bows. I am trying to figure how to make the most of that.
I had a string on it. I marked where the tip was on a background paper at brace height. Then I pulled it back an inch and marked the tip again etc. etc. out to 28". Joined all the dots and the arc from the deflexed limb stayed outside the regular limb. It did get longer. I'll have to do it again, it was a while ago and it's getting kind of faint. :). When I put a recurved tip on it the effect was even more dramatic, although I did use rather big hooks. The string lengthening characteristic of recurves adds to the limb lengthening of the reflex so the net gain is more.
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DC, you are doing a great job, one after another, respect! I just destroyed my latest deflex/reflex-project by stringing it the wrong way - beginners life is hard sometimes but seing others work helps to motivate again! thanx
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Love the angular look to it! very nice! I think that is the style I will be attempting next.
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I look forward to all your posts. Well done!
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I did a little messing around with a piece of bamboo for a test bow. I had noticed that the "lever" of a bows limb gets shorter as it bends because the length of a lever is measured in a straight line from point of effort to the fulcrum. So I bent the bamboo to "brace" height and measured the lever length. Then I bent it to full draw and did the same. As you can imagine the lever got shorter. Then I bent the "limb" into reflex and deflexed it at the handle. When I bent the limb the first part
of the stroke was straightening it so the lever got longer and then it started getting shorter but the net result was that the lever wasn't as short at full draw. I think the deflexed handle helps because it delays or reduces the bend at full draw. This gives more leverage at full draw. When I start thinking about how this affects energy storage my brain kind of rebels on me. The lever length only changes by a few percent but it's a good few percent. Lots of people probably know this but I thought it was interesting.
That works well when its bent without a string. With a string, it cant get longer, that means that because it wants too, its forced to bend further than it otherwise would per inch of draw, storing more energy in that draw inch than otherwise would have been. Its really a damn good design feature, and one I have used in my last two short bows. I am trying to figure how to make the most of that.
I had a string on it. I marked where the tip was on a background paper at brace height. Then I pulled it back an inch and marked the tip again etc. etc. out to 28". Joined all the dots and the arc from the deflexed limb stayed outside the regular limb. It did get longer. I'll have to do it again, it was a while ago and it's getting kind of faint. :). When I put a recurved tip on it the effect was even more dramatic, although I did use rather big hooks. The string lengthening characteristic of recurves adds to the limb lengthening of the reflex so the net gain is more.
Id like to do this with markers tied to the tips. It took some thought for me before the obvious hit me. When the string makes contact with the belly on a recurve, the bow can get longer as its drawn. If not, then it can only get shorter.
Sometimes, the amount of thought I need to put into a simple concept makes me question my own genius. But then, only a fool wouldnt question himself so, I must be good to go :)
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The reflexed bow with a deflexed handle does get shorter but not as much. A straight bows limbs are bent at brace. Our RD bows limbs are straight(or just about) at brace. Like an Egyptian bow.
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I did a little messing around with a piece of bamboo for a test bow. I had noticed that the "lever" of a bows limb gets shorter as it bends because the length of a lever is measured in a straight line from point of effort to the fulcrum. So I bent the bamboo to "brace" height and measured the lever length. Then I bent it to full draw and did the same. As you can imagine the lever got shorter. Then I bent the "limb" into reflex and deflexed it at the handle. When I bent the limb the first part
of the stroke was straightening it so the lever got longer and then it started getting shorter but the net result was that the lever wasn't as short at full draw. I think the deflexed handle helps because it delays or reduces the bend at full draw. This gives more leverage at full draw. When I start thinking about how this affects energy storage my brain kind of rebels on me. The lever length only changes by a few percent but it's a good few percent. Lots of people probably know this but I thought it was interesting.
DC I really like your bow design and impressed by arrow speed. I think it's faster than fiberglass laminated bow. I want to fully understand what you said and others comments about this bow design but i'm not anglophone so it's little bit difficult to understand. If it's possible could you explain intelligibly or with some pictures ?
I think your bow design is close to modern olympic recurve bow is this design better than typical horn bow design ?
and how to make wood laminated bow with your design?
1. for deflex on handle I think gluing two billets with deflex is the only way. is that right? beacuase handle is thick so It's hard to put deflex with dry heat or steam
2. how to put reflex on limbs ? bending with heat or just put on reflex zig after laminate with backing material ?
3. to me it seems there is recurve on tip with large curvature (small radius) how to bend like that? tip thickness is thin? or using kerf cut for bending?
4. edge grain is different with quarter sawn or rift sawn wood?
sorry for my atrocious english ~
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You can readily deflex a handle with steam by thinning the material and then building it back up after bending.
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To tell the truth I printed a few pictures from this thread http://www.primitivearcher.com/smf/index.php/topic,62271.0.html
and taped them on my tillering board. Made a bow that looked the same as the pictures and it worked. I've never worked with horn so I can't say. I've also never made a laminated bow, just self and backed bows.
1. Like PatM says there is more than one way to deflex the handle. Choose the one that works for your skills and tools.
2. This bow had some reflex already but you can glue it all in or prebend with steam. I always glue some in just because I read that Perry reflex is good and it has worked. You can heat treat the belly before glueup if you want.
3. Any or all that you mentioned. Yew is fairly easy to bend. I use this method now. I found that I can get really tight bends with this jig http://www.primitivearcher.com/smf/index.php/topic,62668.msg878994.html#msg878994
4. Edge grain is quarter sawn, same thing. It maybe a local term.
Your English is probably less atrocious than my explanations. Let me know if you need more.
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thanks for kind and explicit reply.
I have some more questions.
1. I read about Perry reflex several times but I still don't understand.. Perry reflex means gluing backing and belly material without prebending ? If it is, it's just normal way to put reflex for backed bow. isn't it ? and what's the advantage of it ?
2. The reason why I mention about horn bow was because of it's design not material. when I see for example korean horn bow profile, when it's unbraced it has only reflex and recurve and when it's braced 5 curves(reflex on handle) If we compare this horn bow design with your angular Egyptian style bow what's the difference ?
3. For wood based backed or self bow, this Egyptian style bow is ideal design when it comes to energy efficiency, arrow speed something like that ?
4. If you used bamboo as backing material, arrow speed would be faster ?
5. if you shoot with your hand not on shooting machine, it could be little bit slower ? or not much difference ?
6. role of deflex handle ?
7. http://www.primitivearcher.com/smf/index.php/topic,62668.msg878994.html#msg878994 (http://www.primitivearcher.com/smf/index.php/topic,62668.msg878994.html#msg878994) if I bend recurve like this, it won't tear? why put strip? because wood take less tension thanks to metal strip? If it is, I must clamp and vise tightly so strip can do his role ?
even myself, i can't understand what i'm talking about... sorry again and thanks in advance
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thanks for kind and explicit reply.
I have some more questions.
1. I read about Perry reflex several times but I still don't understand.. Perry reflex means gluing backing and belly material without prebending ? If it is, it's just normal way to put reflex for backed bow. isn't it ? and what's the advantage of it ?
2. The reason why I mention about horn bow was because of it's design not material. when I see for example korean horn bow profile, when it's unbraced it has only reflex and recurve and when it's braced 5 curves(reflex on handle) If we compare this horn bow design with your angular Egyptian style bow what's the difference ?
3. For wood based backed or self bow, this Egyptian style bow is ideal design when it comes to energy efficiency, arrow speed something like that ?
4. If you used bamboo as backing material, arrow speed would be faster ?
5. if you shoot with your hand not on shooting machine, it could be little bit slower ? or not much difference ?
6. role of deflex handle ?
even myself, i can't understand what i'm talking about... sorry again and thanks in advance
Now you've gotten deep into stuff that I'm not sure of. I believe Perry Reflex more or less the same as gluing reflex has always been done. Dan Perry explained why it works and so his name got attached. There will be some disagreement about this but that's just my take on it. Whatever you call it, it seems to work.
My bow is 64" long, horn bows are usually shorter so that the horn and sinew are worked harder. I'm not really sure but I think the difference is just the use of different material to take more strain. I saw a show about Egypt the other night and apparently Egyptian bows were horn and sinew. I'm not really good with different designs, you'll have to ask someone else.
I've made bamboo backed yew and they are also fast. The maple surprised me but I'd hate to bet on the difference. I'm pretty sure it would be slower, I have a very crummy, inconsistent release. I'm not a good shot.
Role of a deflex handle?? Don't know for sure. I think it uses some of the energy that is normally wasted in bracing but really, I don't know.
Sorry you didn't get better answers.
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The two most important things I think a de flexed handle does is allow the bow to hit full draw with less strain on the wood. The wood is in better shape and take less set thus less hysteresis. The other thing I see is that every part of the limb is responding to its respective angle to the string during all parts of the draw and release. A deflexed limb maintains lower string angles for better energy storage. It also tend to wind back up more cleanly after the shot from the inner limb out getting less vibration and power loss.
Every shooter is different, from 10 fps slower to 10 fps faster in not unusual. The great majority of shooters will shoot about 7 fps slower than the machine.
Perry reflex does help to increase performance, lots of speculation as to why but it does help.
I don't think Bamboo is any faster than other good backings, it is tough and reliable so i like it.
No comment on the Egyptian bows
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Mostly this bow has been shot on the machine in my garage. I took it to the range last Monday and I was really pleased. I now know what "sweet shooting" is. :D I know I'm not pulling it to the 28" mark but the draw is very smooth and even. At 2# per inch I'm probably pulling 37-38# but it feels like a lot less than that. I'm liking this bow.
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thanks DC and thanks Badger i read your no set tiller interestingly
i add question 7 while you answer so could you explain about question 7 ?
and is there any f/d curve of this bow? in light of arrow speed i expect rapid increase of early draw weight. i want to compare it with other recurve bow f/d curve
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7. http://www.primitivearcher.com/smf/index.php/topic,62668.msg878994.html#msg878994 (http://www.primitivearcher.com/smf/index.php/topic,62668.msg878994.html#msg878994) if I bend recurve like this, it won't tear? why put strip? because wood take less tension thanks to metal strip? If it is, I must clamp and vise tightly so strip can do his role ?
even myself, i can't understand what i'm talking about... sorry again and thanks in advance
The vise is lightly clamped down
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That's a sweet bow, DC! Thanks for sharing it with us.
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The vise is lightly clamped down
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if it’s lightly clamped down it doesn’t slip?
then what is the role of metal strip? strip is nothing to do with relieving tention of recurve?
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The vise is lightly clamped down
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if it’s lightly clamped down it doesn’t slip?
then what is the role of metal strip? strip is nothing to do with relieving tention of recurve?
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Of course it slips a little. If it didn't slip then I would be trying to stretch the metal, not good
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I get a virtual mass estimate closer to 71 grains, which puts it on par with some of the best custom carbon and glass bows. The chrono readings are consistent with this, so I don’t doubt the chrono readings or draw weight readings. This is an exceptional bow you made!
Alan
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That's almost exactly what I came up with Allen. 71 grains is super low! Almost too low. DC has done everything right checking and rechecking calibration to his scales. I can't help but think there is some small thing we are missing that would throw that off a little. I have a bow with an almost identical profile that stores more energy. I suspect this bow is storing more energy than we are reading. maybe just a couple of pounds. The two bows build almost identical but mine starts higher. Also his light arrow speeds would suggest a slightly higher virtual mass. Still an exceptional bow either way. So good it draws attention.
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Do the formulae that you guys use take into account string weight, tip weight, that kind of thing?
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Lovely bow and excellent performance.
Most of the time I will reflex the limbs with dry heat before I glue the backing down, if it's a type of wood that reacts well to heat that is, and then add more reflex on glue-up. The bow keeps much more reflex that way. If the wood benefits greatly from heat-treating then I do that as well as I am reflexing it.
That's very interesting, Marc. I have never considered that. I did once attempt to heat treat an entire belly lam all the way through before Perry reflexing and backing, in an attempt to improve decent wood to excellent, but it didn't work well. Even when I put it through my friend's Pizza oven I couldn't get a really even temoper without burning something or leaving patchy spots.
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And congratulations on this bow, DC. She's a beauty.
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Do the formulae that you guys use take into account string weight, tip weight, that kind of thing?
Short answer is yes.
I got about 38.4 ft-lb if stored energy when I smoothed out some of the noise in the force-draw readings. Given the 192 fps reading with a 400 grain arrow, the virtual mass number estimates speeds for any arrow weight. These estimated speeds are within a fps or two of the speeds measured for the lighter and heavier arrows shot. This indicates that the measurements made were consistent with each other and pretty accurate. It did look like the speed reading for the lightest arrow shot was a bit low, but the virtual mass model isn’t 100% with large arrow mass changes. ;)
To put this in perspective, the Modern composite Longbow that holds the current 50# Flight Record has about the same virtual mass as this simple composite wood bow!
Alan
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I always amazes me what a guy can luck into.
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Allen, your stored energy figure was a little higher than the one I had come up with. helps to make more sense. The consistency of the virtual mass projected speeds and actual speeds indicates very low hysteresis and actually comes out extremely clean in the numbers. I guess I am just having a hard time accepting numbers this good with a relatively conservative profile. If there was a mistake in the calculations it would almost have to be something linear and very small. My first guess would be maybe something like a 1# error in the force draw from start to finish adding about 2# stored energy. I realize it is very possible that the numbers really are as good as they look but when they get this good it is really fun to pick them apart and look for the smallest deviation.
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Beautiful bow
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This is incredible. I haven't thought of using edge grain before. Wow! Great performance, elite speeds! Thanks for the force draw curve too.
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I'm not really sure if the edge grain had that much to do with it. I've only done one so I've got nothing to base my guess on but I think the design is where the speed comes from. I have made a few regular grain bows in this design and they are all fast.