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R Ashby
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 Posted: Thu 22 Nov, 2012 2:50 am Post subject: Mongol armour piercing arrows |
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I've read in a couple of places about specially weighted arrows used by Mongols to pierce mail. Does anyone know any details about there- such as how they were made and weighted, compared to other arrows? I've consulted Dr Google, and not found much.
Thanks!
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Kurt Scholz
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| Posted: Thu 22 Nov, 2012 10:05 am Post subject: |
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You find it mentioned in the Mongol regulations on armament for warfare, two bows or a good one and 2 quivers with 30 arrows of which 20 are lighter and 10 heavier.
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Dan Howard
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| Posted: Thu 22 Nov, 2012 12:26 pm Post subject: |
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Does anything specifically note that the heavier arrows are armour-piercers?
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Timo Nieminen
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| Posted: Thu 22 Nov, 2012 12:32 pm Post subject: |
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You don't need any "special" weighting; just heavier is enough. A heavier arrow, from the same bow drawn to the same length, will have more energy and less speed. Better for armour-piercing. A lighter arrow will be faster, but have less energy. Better for long range shooting. It was common enough for military archers to carry both light and heavy arrows.
Turkish light (flight) arrows were about 20g (very light for arrows), and heavy arrows about 40g (still very light, compared to war arrows used elsewhere). Korean military exams used a 32g arrow as the standard arrow, and also used a very heavy arrow. Whether this very heavy arrow represents anything in real military use, I don't know. They came in 3 weights: about 240g (a super-heavy arrow), 120g (comparable to Manchu and Japanese arrows, a little more than English longbow arrows), and 64g. This last type, double the weight of the standard arrow, is quite reasonable for a heavy armour-piercing arrow (double the weight of the light arrow is good).
"In addition to being efficient, all pole arms were quite nice to look at." - Cherney Berg, A hideous history of weapons, Collier 1963.
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Dan Howard
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| Posted: Thu 22 Nov, 2012 1:24 pm Post subject: |
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Light armour maybe. Most metal armour would be resistant to all arrows except for the heaviest arrows shot from the heaviest bows at the closest ranges. I suppose it comes down to how you define "armour" and "pierce".
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Timo Nieminen
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| Posted: Thu 22 Nov, 2012 1:33 pm Post subject: |
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| Dan Howard wrote: | | Does anything specifically note that the heavier arrows are armour-piercers? |
It's the only real benefit you get from the extra weight. You lose range and accuracy, and have more weight to carry around. Even in the absence of literary evidence, it's a good assumption.
Nothing explicit about heavier Mongol arrows as armour-piercers in primary sources comes to hand. From a Mamluk source: "The heavier it is, the greater its power of penetration." (Saracen Archery, Latham & Paterson).
The Mongols did have arrows specifically intended for armour-piercing:
Carpini: "They have other arrows for shooting birds and animals and unarmored men and different kinds of arrows for shooting birds and animals."
Carpini describes the arrowheads as sharpened similarly to a double-edged sword. Saracen Archery says that the best armour-piercing heads are triangular or square section pyramids (which is known to be best for piercing metal plates from modern experiment). Perhaps Mongol heads are not optimised for piercing metal armour? Maybe textile/rawhide optmised?
(Yes, "armour-piercing" needs to be understood as relative, not absolute. Even if relatively more likely to pierce armour, it might still be unlikely. Just a larger small chance to be effective, compared with a tiny small chance to be effective.)
"In addition to being efficient, all pole arms were quite nice to look at." - Cherney Berg, A hideous history of weapons, Collier 1963.
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R Ashby
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| Posted: Fri 23 Nov, 2012 1:35 am Post subject: |
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Excellent info gentlemen- thank you!
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Kurt Scholz
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| Posted: Fri 23 Nov, 2012 10:04 am Post subject: |
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| Dan Howard wrote: | | Does anything specifically note that the heavier arrows are armour-piercers? |
No, nothing calls them specifically armour piercing, but it's a general trend to increase weight for that effect.
Weight increase, for the same or more energy, significantly increases the momentum because speed hardly decreases (that's why the Payne Gelway crossbow test sucks). Projectile penetration is related to momentum transmitted per projectile area(of frontal contact) over time and distance traveled in the penetrated environment.
momentum = mass * velocity
energy = 1/2*mass*velocity˛
(mass*velocity*distance)/(time*area)=energy transmitted during penetration (disregarding that the variables change during the penetration due to energy losses)=
=momentum*distance / (time*area) = (momentum *distance) / [(distance/velocity)*area]
increasing the momentum and decreasing the projectile area are simple solutions for furthest distance travel in armour = deepest penetration
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Timo Nieminen
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| Posted: Fri 23 Nov, 2012 1:20 pm Post subject: |
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Penetration through metal plate depends on energy (and penetrator geometry), rather than momentum as such. Penetration depth into soft tissue (where the main loss of energy is viscous drag) depends on momentum. To get through armour, energy. To do more damage after going through armour, momentum.
Using heavier arrows will give you more energy and more momentum. The increase in momentum will be larger than the increase in energy, but IMO the increase is energy is more important.
"In addition to being efficient, all pole arms were quite nice to look at." - Cherney Berg, A hideous history of weapons, Collier 1963.
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Kurt Scholz
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| Posted: Sat 24 Nov, 2012 4:00 am Post subject: |
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| Timo Nieminen wrote: | Penetration through metal plate depends on energy (and penetrator geometry), rather than momentum as such. Penetration depth into soft tissue (where the main loss of energy is viscous drag) depends on momentum. To get through armour, energy. To do more damage after going through armour, momentum.
Using heavier arrows will give you more energy and more momentum. The increase in momentum will be larger than the increase in energy, but IMO the increase is energy is more important. |
Timo, going through a metal plate requires energy. But the energy increase derived from bows with heavier arrows is not that significant. The lighter(not light!) arrows have already an efficient energy transfer and the heavier ones can just get slightly higher and have a maximum of 1.5 times the energy of the lighter arrows with distance having a major energy decrease effect due to drag! Starting with a more kinetic energy at a slower speed gives you a longer range in which you transfer the same kinetic energy. The energy part can be compensated by closer distance shooting (at 20 meters instead of 30 meters). You might reread the energy formula again, metal armour requires more energy to transit per distance, that's no contradiction to the importance of momentum for distance travelled.
Both types of arrows are for war use (and not ultra light long distance shooting competitions) and both are meant to penetrate tissue. Most armour they have to penetrate before reaching flesh is organic and with metal being rare and in thin plates in the Mongol homeland. This metal did limit vulnerability to arrows. Once you get through the metal, the remaining momentum, as you highlighted, makes a difference in penetration depth. A heavier arrow is better at penetrating the organic armour and body tissue with the remaining larger momentum after losing energy and speed in metal armour. Energy loss is speed loss and will not reduce as much momentum if it's a heavier mass at slower speed.
These arrows are more suitable for causing more severe wounds and have generally better penetration capabilities, naturally including armour penetration. This does not make them special armour piercers as Dan's question highlighted and I admit to having no source on them being special armour piercers. It's just physics that they will be a tad better at this task.
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Timo Nieminen
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| Posted: Sat 24 Nov, 2012 12:08 pm Post subject: |
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1.5 times more energy is not insignificant. When that makes it 120J instead of 80J, that means penetration instead of bouncing off.
| Kurt Scholz wrote: | | You might reread the energy formula again, metal armour requires more energy to transit per distance, that's no contradiction to the importance of momentum for distance travelled. |
This depends on the arrow geometry. If the head is wider than the shaft, once the head is through, the rest will follow with little resistance.
I don't think depth of penetration in soft tissue is the point. Even the light arrows from a warbow have the kind of energy (and momentum) that bowhunters think OK for big game. Compare draw weights of hunting bows with those of warbows.
But armour penetration needs all the energy you can get. You don't know how good your target's armour is; if it's really good, you're not going through it, and if it's good, you might go through it if you have a little more energy.
I don't know much about textile armour penetration, and I don't know whether energy is such a critical factor in it. I expect point geometry matters a lot, especially sharpness. For rawhide lamellar armour, it will be (1) energy, and (2) speed. Speed matters because the armour is somewhat free to move. Given two arrows of the same energy and different momentum (different weight arrows, obviously), the lighter faster one will be more likely to penetrate the armour. The differences between penetration of rawhide and metal will be the amount of energy required to penetrate and the importance of sharpness and/or rigidity.
But mainly, you should already have enough momentum to go through an unarmoured human. You don't need more momentum for soft tissue penetration if you can already go through your target. If they're armoured with metal or rawhide (maybe textile, I don't know),energy is key and even 50% more helps a lot.
(Incidentally, 5.56 NATO typically gives about the same momentum as a 100g war arrow (so, English/Manchu/Japanese arrows), but more than 10 times as much energy. Even with a worse penetrator geometry, it gives much, much better armour penetration.)
"In addition to being efficient, all pole arms were quite nice to look at." - Cherney Berg, A hideous history of weapons, Collier 1963.
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Dan Howard
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| Posted: Sat 24 Nov, 2012 1:26 pm Post subject: |
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| Timo Nieminen wrote: | | (Incidentally, 5.56 NATO typically gives about the same momentum as a 100g war arrow (so, English/Manchu/Japanese arrows), but more than 10 times as much energy. Even with a worse penetrator geometry, it gives much, much better armour penetration.) |
So momentum, on its own, is a lousy indicator of armour penetration potential.
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Timo Nieminen
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| Posted: Sat 24 Nov, 2012 4:00 pm Post subject: |
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| Dan Howard wrote: | | Timo Nieminen wrote: | | (Incidentally, 5.56 NATO typically gives about the same momentum as a 100g war arrow (so, English/Manchu/Japanese arrows), but more than 10 times as much energy. Even with a worse penetrator geometry, it gives much, much better armour penetration.) |
So momentum, on its own, is a lousy indicator of armour penetration potential. |
Yes. Worse than lousy - truly misleading - when looking at penetration of small free-to-move plates, like rows of lamellae in lamellar armour, or plates in brigandine. Also mail. For "free to move" armours like that, you need energy and speed. More momentum but the same energy means less speed, and worse penetration because more of the energy goes into moving the armour rather than piercing the armour.
Why do we see heavy armour-piercing arrows of double the weight of light long-range arrows? Why not 10 times? Arrows 10 times heavier will have a lot more momentum, and a little more energy. The answer is just that momentum isn't what pierces armour.
"In addition to being efficient, all pole arms were quite nice to look at." - Cherney Berg, A hideous history of weapons, Collier 1963.
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Dan Howard
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| Posted: Sat 24 Nov, 2012 6:30 pm Post subject: |
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| Timo Nieminen wrote: | | Why do we see heavy armour-piercing arrows of double the weight of light long-range arrows? |
Do we? People see an arrow that is heavier than normal and assume that it is intended to pierce armour. Is there a period text anywhere that tells us how to make an armour-piercing arrow? I agree with Kurt that it is equally plausible that a heavier arrow was intended to inflict more damage on unarmoured targets. They would be more effective at disrupting horses for example. IMO the primary reason for using heavy English warbows was to cast a decent warhead out to a useful range, not to punch through armour.
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Timo Nieminen
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| Posted: Sat 24 Nov, 2012 8:27 pm Post subject: |
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| Dan Howard wrote: | | Timo Nieminen wrote: | | Why do we see heavy armour-piercing arrows of double the weight of light long-range arrows? |
Do we? People see an arrow that is heavier than normal and assume that it is intended to pierce armour. Is there a period text anywhere that tells us how to make an armour-piercing arrow? |
We have period texts that explicitly say that heavier arrows are better at piercing armour (e.g., Saracen Archery, cited above). We have other period texts that implicitly say that heavier arrows are better at piercing armour (e.g., Japanese texts).
| Dan Howard wrote: | | I agree with Kurt that it is equally plausible that a heavier arrow was intended to inflict more damage on unarmoured targets. They would be more effective at disrupting horses for example. |
This would be more plausible if draw weights were much lower. When the typical warbow + light arrow would go clean through an elk or cape buffalo, what unarmoured target would need more on the battlefield?
| Dan Howard wrote: | | IMO the primary reason for using heavy English warbows was to cast a decent warhead out to a useful range, not to punch through armour. |
You get relatively little improvement in range compared to the improvement in energy. Once the bow reaches the maximum feasible thickness, you get no improvement in range, only improvement in energy. If you want range, use light arrows, and bows with light limbs. The costs for high-energy archery are enough so that it's clear that high energy was a desired goal. This is even in the case where high energy conflicted with long-range performance (e.g., Manchu and Japanese archery).
I have seen it written that past about 130lb for a yew bow, you get no significant improvement in range. Past that, with heavy arrows, you'll get further improvement in armour-piercing.
An arrow won't go through a 3mm thick breastplate, but it might go through a 1mm thick arm or leg. High draw weight bow and heavy arrow are important parts of that "might go through".
"In addition to being efficient, all pole arms were quite nice to look at." - Cherney Berg, A hideous history of weapons, Collier 1963.
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Kurt Scholz
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| Posted: Sun 25 Nov, 2012 3:36 am Post subject: |
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| Timo Nieminen wrote: |
(Incidentally, 5.56 NATO typically gives about the same momentum as a 100g war arrow (so, English/Manchu/Japanese arrows), but more than 10 times as much energy. Even with a worse penetrator geometry, it gives much, much better armour penetration.) |
Timo you did not understand the formula (that is still too simplistic).
Velocity does also effect penetration, but you need a lot more energy for this effect because penetration increase via velocity increase has only a square root increase from the additional energy input. That's always been a solution for systems that are not man-powered, while man-powered systems take the linear momentum increase.
In other words, to increase penetration capability three times you either put 9 times more energy into it via the velocity approach or you triple the weight and need only 3 times the energy for the same effect (but carry a lot more munition weight!). Things are even more difficult if you take the characteristic of mechanical missile throwers into account to have decreasing efficiency with higher missile speed. You can easily arrive at about 15 times the energy required by the mechanical launching system for the same effect if you increase velocity instead of weight. A human now needs to commit to 5 times the effort for the same result. Range is another issue, because the energy will be lost in friction if not using a small high density object like a bullet. For transferring a high speed projectile with a specific energy at a not so close range you need even more energy - double it - and now we have 10 times the energy required for the same effect if using mechanical launchers for arrows. With bullets you release chemical energy and do not want to carry around much ammunition weight.
Plus, take into account that such high speed differences also result in very different behaviors of materials. It's like comparing apples and oranges.
Geometry is another case of apples and oranges. We have zero idea about any other design differences than the weight. I wrote that the frontal contact surface does have a major effect on penetration and integrated it into the formula. You can add the other friction sources as well, but I consider them negligible in comparison as long as it's not about hitting through a shield.
The heavier arrows have slightly slower speed, a bit more energy, much more momentum, very slightly shorter range and a much better energy(and speed) preservation over distance travelled.
The arrows are tools operated by humans, who very well understand what such tools do and act accordingly. In this environment, the lighter and heavier arrows do serve specific purposes. Arrows are not bullets, you see them incoming and do have a limited ability to react to this threat. Speed close to target does make a difference in available reaction time, so the whole weight issue is not limited to armour penetration, but can serve this purpose amongst others.
Last edited by Kurt Scholz on Sun 25 Nov, 2012 4:08 am; edited 4 times in total
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Dan Howard
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| Posted: Sun 25 Nov, 2012 3:41 am Post subject: |
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| Timo Nieminen wrote: | | This would be more plausible if draw weights were much lower. When the typical warbow + light arrow would go clean through an elk or cape buffalo, what unarmoured target would need more on the battlefield?. |
The point is to inflict this level of damage at longer ranges.
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Gary Teuscher
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| Posted: Sun 25 Nov, 2012 8:56 am Post subject: |
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The one area where I see heavier arrows making sense for armour penetration and wounding is that the heavier the arrow, the more efficient the energy transfer from bow to arrow.
This is plainly illustrated in the Karpowicz turkish bow tests. Even the lightest 67.4 pound bows tested were most efficient with a 1548 grain arrow.
However, this is with a huge trade off in velocity - a 1548 grain arrow from this bow has a velocity of 135 fett per second, while the 204 grain arrow had a velocity of 280 feet per second. Which means you are having a great reduction in range and accuracy with the heavier arrow. By the way, a 136 pound draw bow looses the 1548 grain arrow at 180 feet per second.
I think energy, not momentum is key when it comes to penetrating armour. But a heavier arrow has some positive factors to armour penetration merely because of it's mass. It's going to lose less energy when striking the target and bending, a lighter arrow will bend more. It's also less likley to shatter and lose energy for the same reason (talking about the shaft of the arrow, not the head).
There are many other factors as well of course, such as the geometry mentioned. Which arrow type is going to have the best performance when striking armour factors in many things that are certainly beyond by calculations. But it would seem more mass in an arrowhead is less likely to bend/shatter than less mass, all other things being equal.
I think for every bow weight there is an ideal mix of arrow depending upon what one wishes the arrow to do, i.e. range, armour penetration, wounding, etc. A 1548 grain arrow in a 67 pound draw bow is probably never an ideal mix, due to the low exit velocity of the arrow. For some reason, in general eastern and near eastern bows seemed to favor lighter arrows and higher velocity then western ones.
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Timo Nieminen
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| Posted: Sun 25 Nov, 2012 11:51 am Post subject: |
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| Kurt Scholz wrote: |
Timo you did not understand the formula (that is still too simplistic).
Velocity does also effect penetration, but you need a lot more energy for this effect because penetration increase via velocity increase has only a square root increase from the additional energy input. That's always been a solution for systems that are not man-powered, while man-powered systems take the linear momentum increase.
In other words, to increase penetration capability three times you either put 9 times more energy into it via the velocity approach or you triple the weight and need only 3 times the energy for the same effect (but carry a lot more munition weight!). |
No. That's quite contrary to both well-established theory and experimental measurements. It is very clear that penetration through metal armour depends on energy, linearly.
For a good single-volume review, see the armour penetration chapter in Atkins, The Science and Engineering of Cutting.
Most of the armour-penetration research focusses on bullets/shells through thick plate, because that's relevant to modern warfare, so the arrow relevant stuff is a little harder to find. Atkins gives a good review, and cites the most relevant primary research literature. The Knight and the Blast Furnace is also good. A lot of the primary research only gives spot measurements for arrows (e.g., P. N. Jones). Arrow-through-armour research is deficient, and there's a lot of room for more. Good luck to anybody who pursues grant money to such ends! But the main points, that energy is the key, and that slender pyramidal penetrators (if they don't bend) are optimum are well-established.
"In addition to being efficient, all pole arms were quite nice to look at." - Cherney Berg, A hideous history of weapons, Collier 1963.
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Timo Nieminen
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| Posted: Sun 25 Nov, 2012 12:08 pm Post subject: |
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| Gary Teuscher wrote: | The one area where I see heavier arrows making sense for armour penetration and wounding is that the heavier the arrow, the more efficient the energy transfer from bow to arrow.
[...]
I think for every bow weight there is an ideal mix of arrow depending upon what one wishes the arrow to do, i.e. range, armour penetration, wounding, etc. A 1548 grain arrow in a 67 pound draw bow is probably never an ideal mix, due to the low exit velocity of the arrow. |
Yes, very much so. (Not for every "bow weight" though; it depends on both the draw weight of the bow and the mass and geometry of the limbs.)
I'm sure I've posted the graph here, but can I find it? Anyway, see my paper here. Efficiency versus arrow weight is well-known, with stuff from many, many decades ago by Klopsteg, so what I have there is not new.
| Gary Teuscher wrote: | | For some reason, in general eastern and near eastern bows seemed to favor lighter arrows and higher velocity then western ones. |
Except for Far Eastern ones. Japanese and Manchu archery were very heavy-arrow archery. With the Manchu conquest of China, very heavy arrow archery spread westwards through Central Asia, so one sees, e.g., very heavy Crimean Tatar arrows. For Arab/Indian/Turkish/Korean archery, and Mongol/Chinese pre-Qing/Manchu, yes, light arrows were normal. The "some reason" is that they had light efficient bows that could benefit from light arrows - plenty of speed and plenty of energy. You use the arrows that work best with the bow -> lighter arrows -> higher velocity.
"In addition to being efficient, all pole arms were quite nice to look at." - Cherney Berg, A hideous history of weapons, Collier 1963.
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