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Discussion Starter #1
"The 82# Manchu bow, made by Wen Chieh, outperformed a well-made 128# yew longbow, shooting the same 1230 grains (80g) military weight arrow a stunning 190fps against 170fps for the longbow."

The devilish details at:

http://www.manchuarchery.org/bows
 

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Not suprising, that thing has a foot or more reflex, where as the yew bow probably follows the string. The question is though... which one would be more forgiving? :)
 

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Actually in that particular comparison I think you would have a better chance of having control with 82 pounds than 128 pounds.

Todd
That's what I was thinking, but most folks consider a highly reflexed bow unstable. I wonder if the reflex thing is just a side-by-side thing, comparing to equal weight bows.
 

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I think I read the problem with highly reflex bows is that they are unstable in lighter weights being too narrow or tips too heavy for draw weight but as they become heavier the limbs are wider and the tips proportionally lighter in weight becoming more stable and more efficient.

Todd
 

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Cool article, thanks for posting.

This is the line that really caught my attention...

"The champion in a 1728 contest between the one hundred top bowmen in the empire won one hundred taels when he hit the bull's-eye using an eighteen-strength bow an estimated drawing weight of almost 240 pounds!"

:weightlifter: :faint:​
 

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I think I read the problem with highly reflex bows is that they are unstable in lighter weights being too narrow or tips too heavy for draw weight but as they become heavier the limbs are wider and the tips proportionally lighter in weight becoming more stable and more efficient.

Todd
The narrow part makes sense, but the efficiency shouldn't come into the stability. Hmm... now I think I'll have to try playing with some static tipped bows... hmmm...
 

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Discussion Starter #9
The composite, static tip recurves were known to the western Europeans. Roman troops/auxillaries used them all through the empire in Britain, Gaul (France), Germania, and Hispania (Spain). When the empire fell, the bows went w it. Eastern Europeans kept using them though. There are economic/tactical/logistic reasons to prefer a wooden self longbow. They are easier, quicker, and cheaper to make, less bothered by extremes in temp and humidity, and easier to take care of string at heavy weights, etc.

240 lbs!? It's amazing what archers did when it was a matter of life and death, not just fun and games? ;)
 

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How do you string that thing up?

Now you got the wheels turning in Kegan's head...... Guess it won't be too long until I'm test shooting something new. Come to think of it, I'm just about always test shooting something new!:teeth:
 

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Discussion Starter #12
How do you string that thing up?
Very carefully! A slip could result in serious injury w the heavy bows. This limb design is very susceptible to twisting, and if it twisted enough to unstring, serious injury and death could be the result. Stringing could be a two man operation, or special wooden blocks (gong nazi) or peg boards would be used to bend and hold the limbs in increments until fully strung. For the adventurous, a modified step-through w the lower limb on the thigh, pulling the upper limb down, and placing the loop on the lower limb. See: http://www.manchuarchery.org/content/composite-bow-care-and-maintenance
 

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This is probably what Sid was talking about with a super-recurve. What happens is that at brace you're pulling the recurves straight back (making for a very short bow that's very stout, hence the massive increase in weight right off of brace), but as the recurves open up, you suddenly have a ton of leverage (so the longer the siyahs... the better leverage) which makes the bow suddenly butter smooth at full draw. Hence, tons of stored energy. If the siyahs are light enough (or here, you use a heavy enough arrow) all of that stored energy turns into delivered energy.

So, if we could figure out how to deal with that twisting trouble, we could have a 40# bow that shoots a 600 gr arrow at 190 fps... that's more power than my 55# bow...

I have some building to do!!!
 

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Discussion Starter #14
So, if we could figure out how to deal with that twisting trouble, we could have a 40# bow that shoots a 600 gr arrow at 190 fps... that's more power than my 55# bow...

I have some building to do!!!
Yeah, that's what I want! And I want it in a 56 inch bow at 28 inches... ;)
 

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600gr at 190fps would put the kinetic energy close to 50. My buffalo at 50# gets 35 or less. The dorado at 45# sits at 32 on a good day. Put me on the list for 29" draw.
 

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BrokenArrow, you have created a monster...:lol:

I'm going to give static tipped, ultra reflexed longbow limbs a shot first. My current longbow is delivering about 39 KE with a 50# bow and a heavy arrow. The current design only has an inch or so of reflex, and the tips aren't perfectly stiff (flexible tips increase vibration and lower efficiency). If I laminate a wedge into the ends of my Delta Shortbow limbs, I should also be able to lighten the tips up... a lot. The DS limbs on my longer riser will make a 66"-68" bow with about 6" of final reflex. Should be a lot easier to keep straight than a recurve, and hopefully the stiff outer limbs help with the flip-floppy limb issue.
 

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This is probably what Sid was talking about with a super-recurve. What happens is that at brace you're pulling the recurves straight back (making for a very short bow that's very stout, hence the massive increase in weight right off of brace), but as the recurves open up, you suddenly have a ton of leverage (so the longer the siyahs... the better leverage) which makes the bow suddenly butter smooth at full draw. Hence, tons of stored energy. If the siyahs are light enough (or here, you use a heavy enough arrow) all of that stored energy turns into delivered energy.

So, if we could figure out how to deal with that twisting trouble, we could have a 40# bow that shoots a 600 gr arrow at 190 fps... that's more power than my 55# bow...

I have some building to do!!!


pretty much it.

even with the lightest limb mass we have ever made, and a stored energy per pound of draw force at 28, of 1.21 meaning a stored energy of 1.21x50lbs = 60.5ft/lbs of energy, we cant get anywhere near that...
impressive.

all I know is that if the energy is not in the design you cant get the energy out the design. 750grain arrow from a 50lb bow with a sepdf of 1.21 = 190fps with zero loss eg: 100% efficiency.
 

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pretty much it.

even with the lightest limb mass we have ever made, and a stored energy per pound of draw force at 28, of 1.21 meaning a stored energy of 1.21x50lbs = 60.5ft/lbs of energy, we cant get anywhere near that...
impressive.

all I know is that if the energy is not in the design you cant get the energy out the design. 750grain arrow from a 50lb bow with a sepdf of 1.21 = 190fps with zero loss eg: 100% efficiency.
Sid, I'm curious, in a longbow design does increased reflex plump up the FD curve anywhere close to that of a super recurve, or is the design geometry/leverage what gives the design such a fat curve?

I'd just be happy to get another 10 fps out of my longbows at 10 gpp:lol:
 

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Sid, I'm curious, in a longbow design does increased reflex plump up the FD curve anywhere close to that of a super recurve, or is the design geometry/leverage what gives the design such a fat curve?

I'd just be happy to get another 10 fps out of my longbows at 10 gpp:lol:
If we thought it were possible we would have tried it. you would need a very long limb to keep the angles good, and the reason for that is because of the forward preload needed to keep the bulge on the DFC going.

When you preload a longbow limb you do tend to shorten its DFC but you do increase the preload. kinda good but you get stack at longer draws. So if you went for a longer limb, you can elongate that DFC.
but that comes with mass.
so there is a cross over in mass and energy.

what we find interesting, is that the weight of a single inch of limb for glass is heavier than it is for a carbon limb. So limb mass becomes a smaller player.

im going to work on recurves as I know the numbers better off the top of my head.
a working portion of a recurve limb is say 17" long. and at 17" long, for both carbon and glass. but the carbon one is 2200 grains and a glass one is 3000 grains.
deviding the grains per inch gives you the mass per inch of limb.
the higher the number the more mass plays a part in performance.

If you had a limb that utterly NO mass, then you would want a longbow limb to be as long as possible. If you had a limb made of lead, you would want it as short as possible.

so its possible to design a bow with a longer limb extending the preload bulge out. but with less negative effects.

(considering you still need to keep vertical stability and stop it turning into a complete noodle)
 
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