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Sturgeon

Archery Thread

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From another database of wood mechanical properties, with the values sorted by energy density:

 

Locust, black or yellow

906

Walnut, black

815

Ash, blue

813

Elm, rock

779

Ash, white

761

Elm, slippery

724

Locust honey

723

Persimmon

722

Ash, green

706

Cherry, black

695

Maple, red

693

Maple, sugar

690

Redwood

684

Beech

680

Ash, black

679

Elm, American

678

Oak swamp white

667

Beech, blue

667

Dogwood (flowering)

665

Pine, longleaf

644

Birch, sweet

643

Oak, white

642

Gum, red

637

Hemlock, mountain

631

Oak, live

621

Cedar, eastern red

612

Pine, red

606

Oak, black

605

Magnolia, cucumber

603

Applewood or wild apple

603

Oak, red

600

Oak, laurel

595

Pine, eastern white

585

Cedar, northern white

581

Spruce, red

578

Birch, paper

575

Spruce, black

573

Hornbeam

572

Cypress, southern

569

Pine, shortleaf

555

Sassafras

553

Oak, post

551

Aspen

543

Birch, gray

538

Oak, bur

536

Sourwood

529

Tamarack

526

Pine, pitch

523

Douglas fir (mountain type)

516

Gum, blue

515

Pine, loblolly

515

Cedar, western red

514

Douglas fir (coast type)

513

Gum, tupelo

504

Hemlock eastern

504

Gum, black

502

Oak, swamp chestnut

502

Fir, silver

501

Aspen, large tooth

496

Cedar, southern white

493

Maple, silver

493

Cherry, wild red

491

Butternut

488

Larch, western

487

Hemlock, western

483

Chestnut

480

Poplar, balsam

478

Spruce, white

472

Poplar, yellow

470

Sycamore

469

Willow, black

467

Basswood

459

Buckeye, yellow

452

Cottonwood, eastern

448

Oak, canyon live

445

Pine, jack

406

Fir, balsam

404

 

Edit: I had to decompose a table, so the results aren't pretty.

 

Edit 2: here is another good resource for wood mechanical properties.

 

Edit 3: Here too

 

Edit 4: and here is the most-cited list of good-to-bad bow woods.

 

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Okay, so as is the nature of bows nothing worked out like I thought it would.

 

The raw measurements of the bow I ended up with are 150cm long, 2.5cm max width, thickness just under 2cm, almost no tapering and no riser.

 

After the usual issues with tillering the bow looks like so (messed-up aluminium practice arrow for scale):

 

765jj3J.jpg?3

 

I then moved on to heat bending... which was a disaster. Steaming was similarly terrible, with the wood refusing to bend enough to even get started in my handy-dandy bending jig:

 

IkLGWpF.jpg?2

The cracking sounds it made were actually just my soul ejecting itself in shame.

 

From here I'm basically going to finish up by adding what little reflex I can to the tips and putting on a backing. I will try to get some data out, but I'm almost certain that it will break.

 

More to follow.

 

Edit: seriously, fuck heat/steam bending. I always try to do it with pieces which are too thick, and always end up breaking the damn things in the process. The next one will have some siyahs instead.

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Another technical article on bow making.

 

Note table 2, which has the same measure of energy storage which I came up with. The paper dates from 1997 :mellow:

 

Edit - yet another article, this one on bow development.

 

Edit 2 - and another, this time on Scythian-type bows found in China. Turns out that the goofy-looking drawings and sculptures I've seen are actually really accurate representations of the bow.

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Thanks.

Full disclosure: I've made plenty of bows before, but only a few have been even moderately successful. Turns out that a good piece of timber is very important when you're starting out, and I'm generally SOL on that front (edit: plus I'm an idiot who refuses to follow instructions where new and interesting mistakes might be made instead).

People in the US seem to be pretty spoilt, actually, as the access to decent wood is much better than here without resorting to rolling your own or going to specialist lumber yards (eg: red oak). Plus you guys have access to hickory and black locust - both of which are famously good for learner bowyers.

Then again, it looks like kiaat is a superwood for bows and it's pretty much only common in South Africa. So I may just have been literally barking up the wrong tree all these years.

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We were chatting about the comparative cost of bows v muskets somewhere else, and I forgot to mention the big one: storage.

Bows are creations of wood, fibre, horn and sinew. Arrows are much the same. As such, both bows and arrows tend to be complete bastards to store for any length of time. I'm sure that many a quartermaster has been dismayed, once the bugle sounded, to find the vast majority of his stock was warped, rotted or eaten away into useless when needed.

Guns, on the other hand, can go into the armoury for years at a time once you've oiled and greased them. Ditto musket balls. Even powder, which tends to go a bit funny if left to age, can go in for a few years and still work sufficiently well.

Add in the fact that bows can take a long time to make (years in the case of composite bows glued together with fish glue) and you have a clear logistical incentive to switch over to guns asap.

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I think this discussion misses the most fundamental improvement, which is that guns derive their motive power technologically (chemically), not organically. Bows are human powered weapons, and it is always better to replace organic power of one kind or another with technological power, if possible. The reasons for this are that organisms like horses or oxen or especially humans are high investment assets that are best used for the most difficult (in a technological sense) tasks. Consider that when the U.S. Navy recently undertook to reduce costs, the number one priority on their list was to reduce the required manpower, because men were the most expensive element of the Navy, even with goddamn aircraft carriers thrown in.

So guns allowed you to take these valuable and expensive assets that had been specially trained as bowmen, and replace them with a charge of gunpowder. Yes, you still needed someone to load, aim and fire the gun, but that alone significantly reduced costs, as those roles could be filled either by unskilled laymen or assets trained in another area (e.g., cavalry).

The same exact thing is happening right now with pilots. For some missions, a computer has not only proven capable of replacing a human pilot, but is actually better in some circumstances. Therefore whole classes of manned aircraft have become or are becoming obsolete, because that expensive meatspace asset has been replaced by hardware.

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So I finished modifying the bow with siyahs:

 

ak7QYvk.jpg?1

 

The result is very rough and ready, but works quite well. The siyahs are meranti (read: softwood) and are around 12cm long with a 45' angle. I just stuck them on the bottom of the bow, because that is what I have done in the past and it seems to work. The bow is backed and strapped with linen, and has a lighter-weight string. I sealed it with furniture wax because I'm lazy and don't expect it to last that long.

 

The draw is pretty light (converting to 'murican I'd say in the 30-35lb range) and has a nice fast cast with the messed-up aluminium arrow pictured.

 

If I do this again (and I will) I will probably make the bow a bit thicker and round the backs of the siyahs off better to preserve the string.

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More pictures:

 

2xUVnXb.jpg?1

The bow at full draw

 

DWkFmoj.jpg

The arrow head after I muffed a shot and put it into the wall.

 

Further comments:

 

My wife dislikes the string (too harsh for her fingers) and prefers her longbow for draw and release characteristics.

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What is the limiting factor that slows them down?  Power to weight issue?

If you look at the figures I provided, you can see that good steel should store just as much energy per gram as good wood.

 

The issue, I think, is that it is very hard to remove material from steel in such a way as to make full use of the structural strength available. So your bow limbs end up very overbuilt and slow.

 

I think some super-advanced version of 3-D printing could probably allow you to make a really fast steel bow by allowing you to, for instance, honeycomb the core of the limb and make hollow components where needed.

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I think this discussion misses the most fundamental improvement, which is that guns derive their motive power technologically (chemically), not organically. Bows are human powered weapons, and it is always better to replace organic power of one kind or another with technological power, if possible. The reasons for this are that organisms like horses or oxen or especially humans are high investment assets that are best used for the most difficult (in a technological sense) tasks. Consider that when the U.S. Navy recently undertook to reduce costs, the number one priority on their list was to reduce the required manpower, because men were the most expensive element of the Navy, even with goddamn aircraft carriers thrown in.

So guns allowed you to take these valuable and expensive assets that had been specially trained as bowmen, and replace them with a charge of gunpowder. Yes, you still needed someone to load, aim and fire the gun, but that alone significantly reduced costs, as those roles could be filled either by unskilled laymen or assets trained in another area (e.g., cavalry).

The same exact thing is happening right now with pilots. For some missions, a computer has not only proven capable of replacing a human pilot, but is actually better in some circumstances. Therefore whole classes of manned aircraft have become or are becoming obsolete, because that expensive meatspace asset has been replaced by hardware.

I sort of agree and disagree here.

 

I agree because replacing muscle power with stored chemical energy really was a game-changer if you compared muskets with, say, crossbows.

 

But I disagree a bit about bowmen as expensive assets. It really doesn't take too much to train a man to do an area-shoot, nor is the strength required particularly herculean if you're not trying to make the bow an anti-armour weapon. The cult of the longbow has distorted our understanding of archery, so just put all that 'to make a good bowman start with his grandfather' business out of your mind and think about how bows were generally used and what it would take to use them. You will very rapidly come to the conclusion that, if anything, a crossbow or musket is harder to train a conscript on because it is very fiddly and unintuitive to reload. Not to mention: pretty much the worst a bowman can do to himself is break his bow. A gunner making a mistake, on the other hand, ends up doing a fair impression of a suicide bomber.

 

As I said earlier, my take is that guns provide major economic advantages over bows and crossbows - they are cheaper to store and cheaper to field because you've essentially replaced the most expensive part of the system (the arrows) with something easy to make and easy to store (powder and lead shot). This, plus the superior power that a gun provides, would provide more than enough advantage to switch over. That they have the easiest sales pitch ever was just icing on the cake.

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I sort of agree and disagree here.

 

I agree because replacing muscle power with stored chemical energy really was a game-changer if you compared muskets with, say, crossbows.

 

But I disagree a bit about bowmen as expensive assets. It really doesn't take too much to train a man to do an area-shoot, nor is the strength required particularly herculean if you're not trying to make the bow an anti-armour weapon. The cult of the longbow has distorted our understanding of archery, so just put all that 'to make a good bowman start with his grandfather' business out of your mind and think about how bows were generally used and what it would take to use them. You will very rapidly come to the conclusion that, if anything, a crossbow or musket is harder to train a conscript on because it is very fiddly and unintuitive to reload. Not to mention: pretty much the worst a bowman can do to himself is break his bow. A gunner making a mistake, on the other hand, ends up doing a fair impression of a suicide bomber.

 

As I said earlier, my take is that guns provide major economic advantages over bows and crossbows - they are cheaper to store and cheaper to field because you've essentially replaced the most expensive part of the system (the arrows) with something easy to make and easy to store (powder and lead shot). This, plus the superior power that a gun provides, would provide more than enough advantage to switch over. That they have the easiest sales pitch ever was just icing on the cake.

 

Depends what you need done. Yes, I think for technically using a bow of an appropriate weight, i.e. slinging arrows downrange, you don't need anything more than a normal soldier, but you're not getting anything close to the kind of power that even a 14th Century gun gives you. For that you need a trained longbowman. Add into that the fact that Granny isn't much use with a bow, but she can still sling shot downrange, and you've got a much reduced requirement for making effective combat assets. I am not suggesting that you would be fielding whole battalions of grandmothers, of course, but just illustrating how the striking power has been decoupled from the strength and training.

Also, we now think of those early guns as being extremely dangerous (and they probably weren't terribly safe, to be fair), but there are three other things to remember. 1. The guns could be, and were, reinforced to compensate for poor materials. Compare the barrel thicknesses of a 14th Century handgonne with a modern shotgun, and consider that they're running approximately the same pressure. 2. It's very hard to overcharge a muzzle loading, blackpowder weapon. I have seen people load triple the recommended load into muzzleloaders and only break the stock. This is because the chamber volume goes up accordingly with the added powder, and because blackpowder has such a low energy density. This isn't to say it's impossible to blow up a blackpowder gun (though by far the easiest way to do it is to load smokeless powder in one), but that they wouldn't be so dangerous as to constantly be grenading in the hands of untrained conscripts, either. If a gun of the era did explode, it would almost surely be the result of something on the manufacturing end (poorly corned powder, or poor metallurgy), or something related to the gun's or powder's condition. Finally, 3., if your untrained, low investment conscript gets blown up... Well, so what? It's war, and sometimes people die. At least you didn't lose a well-trained archer or arbalestier.

Finally, yes, these guns were crude, and that to some degree tempers their initial impact; that's why archers and crossbowmen stick around for so long. Mostly, I think guns weren't reliable initially. Wind, rain, or other climatic conditions could render them useless hunks of steel, so it was good to have a back-up plan. When they did work, though, they gave you performance an archer couldn't ever hope to match, and anyone could use one.

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I assume you've never fired a matchlock before?

I'm not talking about the gun bursting, I'm talking about the user accidentally touching something off during reload. Again, I'd rate the amount of overall skill needed to use a bow, crossbow or (early) gun in battle as about the same.

You are absolutely right about power, but then an arbalest could just about match the power of a handgonne and get you good accuracy to boot. It also doesn't need any more strength to use.

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I assume you've never fired a matchlock before?

I'm not talking about the gun bursting, I'm talking about the user accidentally touching something off during reload. Again, I'd rate the amount of overall skill needed to use a bow, crossbow or (early) gun in battle as about the same.

You are absolutely right about power, but then an arbalest could just about match the power of a handgonne and get you good accuracy to boot. It also doesn't need any more strength to use.

 

No, but I've fired a handgonne before, which is even worse.

If you have proper dress with clasps for your slow match, that's not really a problem, though.

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No, but I've fired a handgonne before, which is even worse.

If you have proper dress with clasps for your slow match, that's not really a problem, though.

My fucking around with these sorts of things has convinced me that I lack the fine motor control to not explode myself whenever I am required to hold an explosive in one hand and the means of ignition in the other. Bows and arrows, on the other hand, seem to work fine for me.

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Arrow physics:

 

So one of the interesting things about bows/arrows is that, unlike guns/bullets the ammunition itself isn't providing the energy to launch a projectile. Accordingly a bow has a fairly complex relationship between the performance of the whole package and the individual components.

 

In looking at how arrows maketh the bow, we first have to look at how an arrow gets its flying mojo. Simplifying somewhat, there is a transfer of energy from the bow limbs to the arrow as the limbs move and convert their stored potential energy into kinetic energy. This transfer is principally governed by the relative weight of the components in the system and maxes out (velocity-wise) at the point where the bow limbs simply cannot move any faster. There is accordingly a tradeoff between maximum speed (reaching a point of diminishing returns as the limbs get closer to max velocity) and maximum energy (reaching a point of diminishing returns as the arrow speed becomes too slow to be useful as a projectile). Finally, there is a direct relationship between draw length and energy (reaching a point of rapidly diminishing returns as the bow stacks and/or you run out of arm to pull with). This all means that, depending on what you want from your bow, you can diddle with the overall mass of the arrow a bit to trade off speed for energy; with the arrow having a minimum length based on the arms of the user.

 

Once set into motion, the arrow now undergoes some fairly complex dynamic warping due to the force of the string, mass of the arrow and stiffness of the shaft. Archers paradox is pretty well studied, so I won't add much here except to mention the requirement for choosing an arrow with a correct level of stiffness for its length and the draw weight of the bow.

 

Having left the bow, the arrow is now at the mercy of aerodynamics. Here, the length of the arrow, its mass and COG and the drag/lift provided by the flights and head are particularly important. Modern arrows tend to be very light, have a COG close to centre, as little flight drag as possible and are of the minimum length needed to obtain a full draw. This makes perfect sense for target shooting, where you want to extract maximum velocity from a low-poundage bow. It is, however, something of a poison pill for hunting; as it severely limits the size of broadhead you can fit without making your arrow as draggy as hell. I personally favour the idea of significantly longer, forward-weighted arrows to allow for generous head dimensions without sacrificing the performance totally to drag. That this tends to make correct spine less important is just gravy.

 

Once the arrow has gone all the way to target it will have a certain budget of energy left over to do hurty things. This budget is the sum of everything which has come before: the draw energy provided by the bow minus the losses due to vibration and drag. Compared to a bullet the amount of energy available is paltry, but it is nonetheless usually more than enough to drive the arrow deep into flesh and cut a wound channel as wide as the head allows. The factors influencing penetration here are velocity, arrow length and head shape.

 

Based on my understanding and past experience, calculating penetration depth will depend on the target material: flesh can be modelled to a fair degree of fidelity by simply using a drag model, while bone and other hard objects are much more of a pain to model, but tend towards something like Newtonian penetration. Modelling penetration (DeMarre) in steel using these results  as a reference (which should be added to the list of resources for armour testing, in case I forget to do so), we see that penetration in hard targets should scale linearly with increasing velocity.

 

However, it should be noted that modelling of arrow penetration is something of a cottage industry for cranks and people who like physics but hate maths and controlling variables (this is a standard example) and I should not count myself as the exception. As the general consensus here seems to be that momentum is the important factor (with weight being more important than velocity due to the effect of drag), I'm going to tentatively forward that as the 'true' measure of penetration. That it happens to support my long, heavy arrow idea is, I assure you, pure coincidence :) .

 

To sum up, we can take a quick look at what the perfect bow/arrow setup looks like for different purposes:

 

The perfect bow looks the same all over: limbs with negligible mass and the requisite stiffness/geometry to obtain a force draw curve which instantly ramps up to the maximum weight the user can draw comfortably and then stays there until the user runs out of arm to pull with. This maximises the area under the curve and puts as much energy into the system as possible. The perfect string is similarly massless. In the real world a compound bow with a really radical cam setup can get close to this curve, but suffers progressively as you get above 100m/s.

 

The perfect arrow for target shooting is as light as possible to obtain the highest possible speed for the lowest possible draw weight. It is also infinitely thin and of the perfect stiffness to create the correct spine. Its flights are razor-thin and put out the absolute minimum of drag needed to stabilise the arrow in flight. The arrow head is a simple aerodynamic cap, weighted just enough to bring the COG forward of centre. In reality the issue of diminishing returns means that a too-light arrow will suffer from loud release and excess vibration, as excess energy in the bow gets converted to unproductive uses. A very light arrow also suffers from wind drift and the vagaries of drag, as it lacks momentum to plough through disturbed air or compensate for any imperfections in the aerodynamics.

 

The perfect arrow for hunting is as long as possible, as thin as possible and heavy enough so that it is launched at the absolute minimum velocity needed to hit the target with some accuracy. It has a COG very far forwards so that aerodynamic forces from the gigantic broadhead don't overwhelm the stabilisation provided by the tail. Here the realistic ranges are probably something in the order of just over a metre long, with the mass being dependent on the force-draw curve of the bow and the maximum strength of the user. At the outer extreme of this approach you end up with what looks like a short spear being slung from a 100+lb bow - which is very much like traditional hunting and not at all like modern bowhunting.

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By comparison; to a certain level of approximation, every gun using the same cartridge will have the same velocity, energy, trajectory, terminal effect and so on.

 

Um, I get the point you're trying to make, but this is totally wrong.

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Based on my understanding and past experience, calculating penetration depth will depend on the target material: flesh can be modelled to a fair degree of fidelity by simply using a drag model, while bone and other hard objects are much more of a pain to model, but tend towards something like Newtonian penetration. Modelling penetration (DeMarre) in steel using these results  as a reference (which should be added to the list of resources for armour testing, in case I forget to do so), we see that penetration in hard targets should scale linearly with increasing velocity.

 

 

 

Toxn uses drag models to test his arrows on?

 

755684_orig.jpg

 

I know you're the Social Justice Prince, but I can't help that your genetic disposition to being a South African evil bad guy is winning out!

 

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Kidding aside, awesome write up.

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Um, I get the point you're trying to make, but this is totally wrong.

The difference in velocity etc. between a snub-nosed revolver and a full-length carbine firing the same cartridge (example) is about 85%. The performance difference between a 25 pound bow and a 100 pound bow where everything else is the same is about 65%. Change the draw length, string weight, limb design and so on and you can end up with 4x or 5x differences in performance with the same arrow.

 

For all practical intents and purposes bows have a much more dynamic performance relationship between the components than guns do. Hence "to a certain level of approximation". 

 

Feel free to come up with a less clunky way of saying all that and I will gladly include it in the post.

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