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Light efficient bows that shoot the same arrow faster than a powerful (Read 2092 times)
AncientCraftwork
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Light efficient bows that shoot the same arrow faster than a powerful
Mar 5th, 2021 at 7:20am
 
https://www.youtube.com/watch?v=m5ZUD8PyKAU&ab_channel=MeadLongbows

Interesting video for those interested in light poundage but efficient bow design
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Oxnate
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Re: Light efficient bows that shoot the same arrow faster than a powerful
Reply #1 - Mar 5th, 2021 at 5:32pm
 
Video doesn't really tell you much.

But from what I remember from the Traditional Boyer's Bible, the pyramid design is the most efficient, which all their bows seem to exhibit.

Bow should look like this: <->  (tip, then growing slowly wider to handle.  Then narrowing again to other tip.)

The next most important thing is recurve. 

Then finally, a sinew backing (especially if applied while the bow is under reverse strain) will also increase arrow speed per pound of draw weight.
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Re: Light efficient bows that shoot the same arrow faster than a powerful
Reply #2 - Mar 5th, 2021 at 7:38pm
 
I’ve always struggled shooting lighter poundage bows as apposed to heavier draw .
There’s something about a heavier draw that feels more stable in my hands, lighter bows I tend to notice my flaws in form more often.
I’m not a speed freak, I’m happy if a slow arrow hits its mark.
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Re: Light efficient bows that shoot the same arrow faster than a powerful
Reply #3 - Mar 5th, 2021 at 9:13pm
 
I shot a 64 lb bow for well over a decade. Found and bought a 47 lb  Fred Bear bow in antique shop. Loved it. Still would much rather use a 45 lb bow than anything over 50lbs.
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Re: Light efficient bows that shoot the same arrow faster than a powerful
Reply #4 - Mar 5th, 2021 at 9:21pm
 
Really good efficiency can make a bow shoot like it weighs 15-20 pounds more than it is. Efficiency and durability are on the opposite ends of the bow making spectrum. Got to hit a sweet spot based on your needs.
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Re: Light efficient bows that shoot the same arrow faster than a powerful
Reply #5 - Mar 6th, 2021 at 5:53am
 
Yes, the video doesn't tell much, it's more inspirational to work smarter not harder.

I do 24 hour fasting now and then for various reasons. On am empty stomach and not much energy,  I learn that I don't like to draw anything heavier than 30 pounds. Maybe 40 pounds if if my body gets used to longer intervals without food. A lightweight bow starts feeling like a heavyweight bow when you are low on energy and your muscles are being burned.

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Re: Light efficient bows that shoot the same arrow faster than a powerful
Reply #6 - Mar 11th, 2021 at 5:59pm
 
This is something that has been known for quite a while now? I really don't like this almos Lars Andersen like way of pretending something is a new development or discovery when it has been around for forever. Though maybe these guys just didn't know about it.

Anyhow, you can't quite judge a bow by its poundage, except in how hard it is to pull back. The English (Welsh, really) warbow isn't particularly efficient, but boy oh boy, is it dirt cheap.

The most efficient traditional design for a bow is now understood to be a Turkish/Ottoman bow, that looks like this:

...

Not the most historical image, but it lets you see how the thing is strung. Here's an actual historical example, detail of end of limb, Nurnberg museum, 17th century:

...

The three things to note are light limbs (so little wood they were reinforced with bone or horn), being bent the opposite way when unstrung (this is more of a result of need to make it small enough for mounted use) and the straight ends that are kinda pointing forward.

That last bit is not unique to Turkic bows, you also see it in Burgundian and Italian bows, among many others.

Maciejowski/Morgan Bible, made in France, 1250:

...

Richard Galloway, a well-known bowyer, claims this sort of recurve improves the performance of the bow by 20 percent with bows of equivalent poundage, which is... a lot. If you can get 20% from a traditional bow, I imagine you could get even better gains once you start to experiment with modern materials.
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Re: Light efficient bows that shoot the same arrow faster than a powerful
Reply #7 - Mar 11th, 2021 at 10:27pm
 
Martin_Greywolf wrote on Mar 11th, 2021 at 5:59pm:
Anyhow, you can't quite judge a bow by its poundage, except in how hard it is to pull back. The English (Welsh, really) warbow isn't particularly efficient, but boy oh boy, is it dirt cheap.


Yes, the reason for this is it is the area under the force vs. distance curve that matters. i.e. the amount of stored energy in a bow. For the same final draw distance and weight, If you have a bow that very quickly reaches it's max draw weight and then continues to hold that amount of weight as it is drawn further, it will store more energy than a bow that just linearly increases in draw weight.  The shape of this force vs. distance curve is purely controlled by the geometry of the bow. As it stands, it is difficult to improve on a traditional bow because the shapes have been optimized over the years to store the maximum amount of energy for a given final draw weight.  Modern materials might be able to improve this to a small degree, but I bet an optimized computer-based machine-learning genetic algorithm would end up with a very similar design to turkish/korean/chinese style composite bows.
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Re: Light efficient bows that shoot the same arrow faster than a powerful
Reply #8 - Mar 12th, 2021 at 5:37am
 
Martin_Greywolf wrote on Mar 11th, 2021 at 5:59pm:
This is something that has been known for quite a while now? I really don't like this almos Lars Andersen like way of pretending something is a new development or discovery when it has been around for forever. Though maybe these guys just didn't know about it.

Anyhow, you can't quite judge a bow by its poundage, except in how hard it is to pull back. The English (Welsh, really) warbow isn't particularly efficient, but boy oh boy, is it dirt cheap.

The most efficient traditional design for a bow is now understood to be a Turkish/Ottoman bow, that looks like this:


Not the most historical image, but it lets you see how the thing is strung. Here's an actual historical example, detail of end of limb, Nurnberg museum, 17th century:



The three things to note are light limbs (so little wood they were reinforced with bone or horn), being bent the opposite way when unstrung (this is more of a result of need to make it small enough for mounted use) and the straight ends that are kinda pointing forward.

That last bit is not unique to Turkic bows, you also see it in Burgundian and Italian bows, among many others.

Maciejowski/Morgan Bible, made in France, 1250:


Richard Galloway, a well-known bowyer, claims this sort of recurve improves the performance of the bow by 20 percent with bows of equivalent poundage, which is... a lot. If you can get 20% from a traditional bow, I imagine you could get even better gains once you start to experiment with modern materials.


Geez, I’m going to be “that guy” again. For the sake of clarity and accuracy in this forum. Not picking on you Greywolf, I promise, but need to clear some things up.

Anyhow, you can't quite judge a bow by its poundage, except in how hard it is to pull back. The English (Welsh, really) warbow isn't particularly efficient, but boy oh boy, is it dirt cheap.

True. Good point.

The most efficient traditional design for a bow is now understood to be a Turkish/Ottoman bow, that looks like this:

Not the most historical image, but it lets you see how the thing is strung. Here's an actual historical example, detail of end of limb, Nurnberg museum, 17th century:

The three things to note are light limbs (so little wood they were reinforced with bone or horn), being bent the opposite way when unstrung (this is more of a result of need to make it small enough for mounted use) and the straight ends that are kinda pointing forward.


The truest part of this statement is the fact that this is an actual historical example of a bow.

Efficiency in bows is on it’s simplest terms energy in vs energy out.

That being the case any bow can be efficient if you use a heavy enough arrow. All you need is an arrow so heavy it shoots slow enough that it drains every last bit of energy in the limbs. This combined with keeping limb mass as low and energy storage as high as possible makes a super efficient brick thrower. Worthless for anything besides paving your driveway but using the definition of efficiency in it’s most straightforward and stripped down definition it is the world’s most efficient bow. So the world’s most efficient war bow should come with the world’s most efficient casket because frankly the person using it would need it soon after entering battle. Efficiency has to be balanced with durability and the bows purpose.

The Turkish bow is not the most efficient bow. It’s not even the most efficient composite bow. Very, very debatable assertion. Korean bows store more energy with less mass. They are also more highly reflexed and shoot very, very hard at war bow levels. They are also extremely unstable and prone to weather damage as were all the horn/sinew/hide glue bows making it a great but touchy weapon. Not accurate at all compared to English longbows which are a thing of simple beauty personified.

If any horse bow can be said to be most efficient it would have to be the Korean. Turkish crab bows were very good in war bow ranges but people don’t compare bow efficiency in war bow poundages in todays world. Even 500 hundred years ago when they did it wasn’t the most efficient.

The three things to note are light limbs (so little wood they were reinforced with bone or horn), being bent the opposite way when unstrung (this is more of a result of need to make it small enough for mounted use) and the straight ends that are kinda pointing forward

1. For the volume the limbs were much heavier than wood alone. The sinew/hide glue matrix was approx. twice as heavy as wood. The horn I wont quote exactly but is also considerably heavier than wood.

2. The intense reflex and recurve was done because of mounted archers. Sinew and horn were used however as a side effect of using such short bows. Short bows store very little energy for the equivalent draw weight of a longer bow. Master bowyers of that time knew all about this. Their solution to having a bow suitable for warfare via horseback was to use materials that were much, much stronger in tension and compression and with a much greater elastic modulus to allow them to put in huge amounts of reflex and recurve so as to bring the bows power back up to high levels even when using very short bows.

The bow was not reflexed and recurved to make it short enough to use from horseback. You are putting the cart before the horse. The bow was short enough to shoot from horseback and therefore had to be reflexed and recurved. It had nothing to do with shortening the bow and everything to do with solving the low efficiency problem of very short bows.

The “straight ends kind of pointed forward” are called siyahs. They are all about energy storage but create as many problems as they solve.


Richard Galloway, a well-known bowyer, claims this sort of recurve improves the performance of the bow by 20 percent with bows of equivalent poundage, which is... a lot. If you can get 20% from a traditional bow, I imagine you could get even better gains once you start to experiment with modern materials.

Not so. Again, only higher draw weights suitable for war. Bows such as this are horrible at normal hunting weights. This across the board assertion should be much more specific.

The reason for this is the siyahs themselves with all the recurve and reflex in the bow. Such a wildly reflexed/recurved bow is incredibly unstable. Prone to both reversing in the hand, shedding it’s string and then dying in a blaze of glory when an immense amount of energy storage goes out not with the arrow but into the limbs. This is not uncommon even in todays modern reproductions.

To make them more stable the siyahs had to be made wide enough to grant such stability also sometimes with a bridge attached for the string. All further increasing the bows mass and lowering efficiency. But these bows had plenty of energy to spare...unless they were not heavier bows. At 60# and less I can make a wooden modern “mass principled” bow that will mop the floor with an equivalent weight horn bow. Horn bows get around their problems by brute force. Got a problem? Store more energy! Faster arrow speeds? Store more energy! Your wife is cheating on you? Store more energy!

That’s their solution. “But” if you are already self-limiting the amount of energy you are going for to even a decent weight hunting bow you don’t have that option. Because although you can make it as efficient as the materials allow, you can only store so much energy in a 60# bow. At war bow ranges though they will destroy a wooden longbow.

But why would that matter? Can’t you just make the composite bows limbs narrower and decrease mass but keep the same reflex and recurve for huge energy returns? No. No you can’t. This is where the siyahs come in and make trouble.

Such an extreme reflex/recurve required siyahs with much wider and heavier outer 1/3 limbs. You need a certain amount of width to keep such a limb from twisting and breaking the bow. But that width doesn’t increase much as the bows weight goes up. The thickness might but the width is good. This increased mass greatly reduces efficiency since the outer 1/3 of the limbs travels the furthest and therefore saps the most energy.

Modern wooden longbows accomplish their speed by going the opposite route. They choose not to store so much energy but their outer 1/3 of their limbs can be very narrow. So narrow you would be sure it would have to break. There is no danger of the limb twisting because the high reflex isn’t needed to increase energy storage so these very low mass limbs give excellent energy transfer. So actually they are more efficient at transferring what energy they do have but they store much less total energy.

So the longbow in this scenario is a low earth orbit plane traveling with very little to any wind resistance and therefore able to stay at incredible speeds with low energy. The composite bows are fighter jets that are high strung and high energy. Not a perfect analogy but hopefully it gets the point across.

As for modern materials. Of course they have higher elasticity per mass with strings that are much lower mass per strength. Yes modern bows can be faster but the difference, especially with a master crafted, heat tempered, mass principled bow is not that much. Not that much for materials invented post moon landing vs trees that have been used for thousands of years.

The deer won’t stop and ask if your bow shot him with 10-15 FPS more speed. The arrow is still going to zip right through him and he will be just as dead. And the longbow will be far and away more accurate and stable. A slower hit is better than a faster miss. Every time.

Since no country with a national budget greater than a rusty tricycle uses bows in war, having a 20% increased performance (which is a very general assertion as well) doesn’t really do much of anything in modern terms or usages.


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Re: Light efficient bows that shoot the same arrow faster than a powerful
Reply #9 - Mar 12th, 2021 at 5:56am
 
stick shoot stick  Shocked make stick bend shoot stick fast  Mad Monkey
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Re: Light efficient bows that shoot the same arrow faster than a powerful
Reply #10 - Mar 12th, 2021 at 8:43am
 
Damn..I broke J. Where is that super glue again?
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