How much energy is required to penetrate plate armour?
From "The Knight and the Blast Furnace", we have for mild steel (0.15% carbon), hitting straight on (at normal incidence, rather than a glancing blow), the following energies (in joules) required for penetration:
Thickness Arrow Bullet
1mm 55J 450J
2mm 175J 750J
3mm 300J 1700J
4mm 475J 3400J
Historical armours would have had higher slag content, and could have been substantially weaker. The best armours were hardened steel, so stronger. For different irons/steels, you can multiply these energies by:
Munition quality iron: 0.5
Low-carbon steel: 0.75
Medium-carbon steel (Milanese): 1.1
Hardened steel: 1.5
Add to these energies about 50J to defeat padding (e.g., 16 layers of linen), and perhaps 50J to actually cause serious injury or death. (Williams uses slightly higher values, for a total of 150J after the plate is penetrated.)
So, 1mm low-carbon steel plate + padding needs arrows with about 120J to defeat armour and wearer, 2mm plate needs about 230J, 3mm plate 325J.
Also from Williams, an arrow with 120J could penetrate mail (real 15th century mail) and padded jack. So, to defeat armour and wearer, 170J.
So 1mm plate looks inferior to mail, and 2mm plate much better. If you want to stop close-range archery with mail, use heavier mail and/or more/better padding than in Williams' test. Lamellar of about 1.2mm looks comparable to mail.
So, we can assume that 2-3mm plate is good against most archery, including most crossbows. Not adequate against the better firearms (1500J should be defeating 3mm low-carbon steel plate, 1000J for 3mm iron); a pistol or carbine would give about 1000J, arquebus 1200-2000J, muskets 2-3000J.
Soft armours require about 100J to defeat with a blade (or more, if thicker, 100-180J to defeat 5-26 layers of linen). This is more than needed by an arrow; the arrow is better at making holes for the same energy. Good mail and plate will be cut-proof - about 200J to defeat mail with an edged weapon, more against plate. More than most people will manage, but possible. Williams has 60-130J for approximate energy of sword and axe.
This gives a good base for estimating the effectiveness of armour against archery and firearms: 2-3mm low-carbon steel plate to stop archery, 8-9mm of iron to stop short-range musketry.
For sword and axe, mail + padding is good, or the thicker jacks. Of course, also plate (unless possibly the very thinnest and worst?).
What about other armour-piercing weapons?
Javelins might reach 250-300J, and might defeat arrow-proof armour. From literature, we know javelins are good against armour (Roman sources praising the pilum for penetration, though to Conquistadors noting the effectiveness of javelins).
From home experimentation, polearms can be effective. Long hafts allow a lot of energy to be delivered. How much? This could be estimated from high-speed video, from which the speed of the head of the weapon can be measured, and with the mass of the head, gives the kinetic energy of the head. It might be possible to obtain a reasonable estimate using a ballistic pendulum (this would give the momentum of the weapon, but from this, the kinetic energy can be found). I don't have any numbers for polearm energies, and can't find any. Does anybody have anything that might be of use? Anybody willing to try making a measurement? If the energy exceeds 200J, then they should be a good weapon against light armour (mail, thin plate).
Maces and other blunt weapons are highly-praised for anti-armour effectiveness. I don't think we can say much about these on the basis of energy required to penetrate armour, since they don't penetrate the armour.
Where are you getting the notion that you add an additional 50 J to Williams' figures to defeat the wearer? My understanding is that's already assumed in the tests. At 120 J, mail fails enough to allow potentially fatal penetration. You certainly don't need 50 J to pierce skin and flesh with a pointed weapon; sharp points can do that with a mere 1-3 J. If it took 170 J to kill through mail with an arrow, this would have hardly ever happened. Only a heavy yew warbow with a heavy arrow would manage so much as 150 J as close range.
As far as kinetic energy figures for close-range weapons go, I haven't found much concrete. Modern measures of the underarm thrust with knife peak at 72 J, while overarm gets up to 115 J. Most folks can only manage 20-30 J, or even less, which further refutes the notion that you 50 J to inflict a serious injury. A test of a two-foot stone mace, presumably wielded in one hand, produce the result of 130 J. Baseball bats and golf clubs seem to deliver 200-400 J in the hands of professional athletes. As such, I think Williams underestimates the kinetic energy of swung weapons. I imagine simple single-handed sword thrusts from experienced warriors/soldiers would be 60-80 J at the least because swords weight more than knives and the person to got 72 J wasn't a giant or anything.
As far as kinetic energy figures for close-range weapons go, I haven't found much concrete. Modern measures of the underarm thrust with knife peak at 72 J, while overarm gets up to 115 J. Most folks can only manage 20-30 J, or even less, which further refutes the notion that you 50 J to inflict a serious injury. A test of a two-foot stone mace, presumably wielded in one hand, produce the result of 130 J. Baseball bats and golf clubs seem to deliver 200-400 J in the hands of professional athletes. As such, I think Williams underestimates the kinetic energy of swung weapons. I imagine simple single-handed sword thrusts from experienced warriors/soldiers would be 60-80 J at the least because swords weight more than knives and the person to got 72 J wasn't a giant or anything.
Williams defined plate failure as penetration by 40mm or more (p. 929).
| Benjamin H. Abbott wrote: |
| Where are you getting the notion that you add an additional 50 J to Williams' figures to defeat the wearer? My understanding is that's already assumed in the tests. At 120 J, mail fails enough to allow potentially fatal penetration. You certainly don't need 50 J to pierce skin and flesh with a pointed weapon; sharp points can do that with a mere 1-3 J. If it took 170 J to kill through mail with an arrow, this would have hardly ever happened. Only a heavy yew warbow with a heavy arrow would manage so much as 150 J as close range.
|
Williams adds 150J to the energy needed to penetrate plate (see pg 935, also repeats the 150J on pg 946). In the discussion on pp. 946-947, Williams takes the energy needed to penetrate the plate, and adds 50J to this for underlying padding, and compares this to the 120J needed to penetrate mail + jack. That is, he uses 100J less to compare with the mail + jack than he states for what is needed to defeat plate armour + padding and seriously wound the wearer.
So, either he compares apples and oranges, or he's only considering the 120J to be what's needed to penetrate the mail + jack, and not seriously wound the wearer.
His additional 100J is excessive. In Karger et al., "Experimental Arrow Wounds: Ballistics and Traumatology", Journal of Trauma-Injury Infection & Critical Care 45(3), pp 495-501 (1998), 30J of arrow is sufficient for 20-40cm penetration into non-bone pig tissue and tissue simulants. Warbows will do even better - penetration into soft tissue is limited by viscous drag, so close to proportional to momentum rather than energy; heavy arrows will have more momentum and thus better penetration for the same energy.
Taking the energies required for the penetration of plate + 50J for padding, or the 120J for mail and jack, is quite reasonable. I compromised between an additional 0J and Williams' additional 100J (after the padding) for 50J. He says 50-80J for padding, and 50-60J to wound, but uses a total of 150J for both, and only 50J for padding alone. A little more clarity and consistency would be nice.
(Perhaps his 50-60J comes from bullets?)
| Benjamin H. Abbott wrote: |
|
As far as kinetic energy figures for close-range weapons go, I haven't found much concrete. Modern measures of the underarm thrust with knife peak at 72 J, while overarm gets up to 115 J. Most folks can only manage 20-30 J, or even less, which further refutes the notion that you 50 J to inflict a serious injury. A test of a two-foot stone mace, presumably wielded in one hand, produce the result of 130 J. Baseball bats and golf clubs seem to deliver 200-400 J in the hands of professional athletes. As such, I think Williams underestimates the kinetic energy of swung weapons. I imagine simple single-handed sword thrusts from experienced warriors/soldiers would be 60-80 J at the least because swords weight more than knives and the person to got 72 J wasn't a giant or anything. |
He uses 200J for halberds, which seems low in light of literary descriptions of the effect of halberds. Some measurements of bills and halberds would be very interesting. Perhaps I should make a ballistic pendulum and try it out.
His 60-130J looks like it's for one-handed swords and axes (he doesn't specify). His only relevant published reference seems to be Horsfall, I. et al. "An assessment of human performance in stabbing" Forensic Science International" 102 (1999) 79 - 89, which is knives (and the source of your 115J figure?).
(Stab energy as measured by Horsfall looks OK for setting requirements for anti-stab armour, but is less relevant for soft targets. If the wielder keeps pushing the weapon as it penetrates, that's additional work being done, i.e., additional energy, beyond the initial impact energy, being supplied. I know that I can cut up stuff with a kitchen knife that starts in contact with the food with 0J of energy.)
Where does the 130J mace figure come from?
There isn't enough detail given for non-arrow/bullet weapons by Williams. We know that penetration through jacks etc. varies depending on whether one just chops into the target, or uses a draw cut (or thrusts). Soft armour penetration also depends a lot more on sharpness. The figures for plate penetration are more reliably usable.
Various strange inconsistencies appear throughout The Knight and the Blast Furnace. The additional 100 J doesn't appear in most of his examples. See the pikeman on 947, for instance. On page 943, he notes that at 120 J, the arrowhead put a 35mm dent in the plastilene behind the modern mail and jack. How tough is plastilene? Even if it's only as resistant as human skin and flesh, 1.4 inches of penetration in the right spot could be fatal.
| Benjamin H. Abbott wrote: |
| Various strange inconsistencies appear throughout The Knight and the Blast Furnace. The additional 100 J doesn't appear in most of his examples. See the pikeman on 947, for instance. On page 943, he notes that at 120 J, the arrowhead put a 35mm dent in the plastilene behind the modern mail and jack. How tough is plastilene? Even if it's only as resistant as human skin and flesh, 1.4 inches of penetration in the right spot could be fatal. |
That's probably why he chose 35mm. Because he decided that it would be the minimum required for a potentially fatal wound.
Just out of curiosity, does anyone know the ring measurements of the 15th century mail Williams tested? I am asking because I have seen a great amount of variation in 14th and 15th century mail. Some is very light and clearly designed to be worn under some form of plate armour, while others seem to be heavy enough to be used as standalone armour.
IIRC one of the test pieces was a 15th C voider and the other was a replica made by Erik but I don't have any other details.
Oh I see. I think the test would have done much more justice to mail had he used a replica patch of a 14th century hauberk such as the one in the Cleveland museum. With the exception of the groin area, most voiders covered non vital areas of the human body and so I would imagine they would have had lighter rings than those used to cover the chest in a hauberk.
The armpit is definitely a vital area. A wound here can sever the brachial or subclavian arteries and the nerves controlling the arm before puncturing the lungs and the heart.
Just the muddy the waters, I'll mention the rather high energy figures one finds for the simple punch. Rocky Marciano supposedly managed 1,254 J. I don't know what to make of such accounts. As an aside, the kinetic energy of a guillotine blade has been calculated at 300 J. So that's an upper limit for reliable decapitation.
| Benjamin H. Abbott wrote: |
| Just the muddy the waters, I'll mention the rather high energy figures one finds for the simple punch. Rocky Marciano supposedly managed 1,254 J. I don't know what to make of such accounts. As an aside, the kinetic energy of a guillotine blade has been calculated at 300 J. So that's an upper limit for reliable decapitation. |
Benny, that's apples and kumquats. A guillotine blade is extremely fine and functions as a shear. A punch is measured by blunt force exerted over a relatively rectangular area. Useless comparison.
We might as well measure the comparative velocity of breaking wind to a near miss with an open hand. :lol:
Last edited by Kel Rekuta on Sun 25 Mar, 2012 11:09 pm; edited 1 time in total
| Dan Howard wrote: |
| The armpit is definitely a vital area. A wound here can sever the brachial or subclavian arteries and the nerves controlling the arm before puncturing the lungs and the heart. |
How odd that is the most attractive target for a thrust. Hardest to armour, easiest to puncture with a high rate of injury... much like the groin. No one wants to talk about how many arrows to the gronnies it would take to topple a fully kitted man at arms, just about penetrating breastplates and helmets... ;)
| Dan Howard wrote: |
| IIRC one of the test pieces was a 15th C voider and the other was a replica made by Erik but I don't have any other details. |
The original piece is Specimen 3 in Williams, A.R. "The manufacture of mail in Medieval Europe: a technical note" Gladius 15 105-134 (1980). Williams doesn't give ring diameter, wire thickness or such information in this paper; he discusses the metallurgy (crystal structure, hardness, slag content (and carbon content and alloy composition for some other specimens of steel and brass mail)). Specimen 3 is wrought iron. Williams writes: "The wire from which this link has been made was evidently drawn from a bar of very heterogeneous composition. ... Only a little slag is visible."
| Kel Rekuta wrote: |
| [Benny, that's apples and kumquats. A guillotine blade is extremely fine and functions as a shear. A punch is measured by blunt force exerted over a relatively rectangular area. Useless comparison. |
It wasn't a comparison. I mentioned the guillotine kinetic energy figure as an aside. The punch numbers, however, do suggest that Marciano could have put a katar through a 3mm breastplate of the best steel. I find this exceedingly unlikely. If the Marciano measurement is at all correct, I doubt it applies to penetrating armor. If punching just delivers more energy than hand weapons, it's probably does so over a long period of time or in a different manner. The bottom line is that we need more studies of the kinetic energy delivered by swords, axes, spears, and so on.
| Benjamin H. Abbott wrote: | ||
It wasn't a comparison. I mentioned the guillotine kinetic energy figure as an aside. The punch numbers, however, do suggest that Marciano could have put a katar through a 3mm breastplate of the best steel. I find this exceedingly unlikely. If the Marciano measurement is at all correct, I doubt it applies to penetrating armor. If punching just delivers more energy than hand weapons, it's probably does so over a long period of time or in a different manner. The bottom line is that we need more studies of the kinetic energy delivered by swords, axes, spears, and so on. |
Punches can probably indeed have even greater energy, knees and kicks even more, as they are obviously different kind of motions.
I seriously doubt that Marciano, or anyone would be able to achieve the same energy with katar, let alone transfer it smoothly, without a lot of shock etc.
Different mechanics even on similar lines of attack, aside from the fact that I'm pretty sure that Marciano's record punch was a hook, which probably wouldn't be very useful with katar in hand.
The book From Sumer to Rome includes kinetic energy numbers for various ancient weapons. I'm skeptical that these tests reflects what experienced historical warriors managed. The sling figure of 21.7 J, for example, strikes me as laughable. The best baseball pitchers can impart over 150 J without any mechanical aid. If ancient slingers only achieved 21.7 J, they'd hardly have hurt anybody, much less performed the feats attributed to them. Calculations based on contemporary distance records suggest a kinetic energy of up to 400 J with heavy projectiles, which makes far more sense. The From Sumer to Rome test assigns nearly the same kinetic energy (137 J) to gladius swing and stone mace blow despite the wildly different balance on the mace. They conclude that the 1.8lb mace could not knock someone out through a helmet and note its decline as a military weapon in ancient armies. Maybe, but if that's the case, then later maces must have performed much better. We have various accounts to indicate that 15th- and 16th-century cavalry maces could induce unconsciousness through a helmet. It's important to remember that hand weapons don't generate kinetic energy, people do. I have a feeling we should double (or triple, quadruple, etc) the numbers from most tests of modern folks. After all, most archers these days draw 50-60lb bows, while military archers drew 100-180lbs.
| Benjamin H. Abbott wrote: |
| The book From Sumer to Rome includes kinetic energy numbers for various ancient weapons. I'm skeptical that these tests reflects what experienced historical warriors managed. The sling figure of 21.7 J, for example, strikes me as laughable. The best baseball pitchers can impart over 150 J without any mechanical aid. If ancient slingers only achieved 21.7 J, they'd hardly have hurt anybody, much less performed the feats attributed to them. Calculations based on contemporary distance records suggest a kinetic energy of up to 400 J with heavy projectiles, which makes far more sense. The From Sumer to Rome test assigns nearly the same kinetic energy (137 J) to gladius swing and stone mace blow despite the wildly different balance on the mace. They conclude that the 1.8lb mace could not knock someone out through a helmet and note its decline as a military weapon in ancient armies. Maybe, but if that's the case, then later maces must have performed much better. We have various accounts to indicate that 15th- and 16th-century cavalry maces could induce unconsciousness through a helmet. It's important to remember that hand weapons don't generate kinetic energy, people do. I have a feeling we should double (or triple, quadruple, etc) the numbers from most tests of modern folks. After all, most archers these days draw 50-60lb bows, while military archers drew 100-180lbs. |
I agree that 21.7 J is much lower than an experienced ancient slinger would deliver., but 400 J seems a bit excessive.
I recall ancient Greek/Roman writers mentioning the slings ability to penetrate unprotected skin and cause bruises through leather armour, but it doesn't seem to have been a very effective weapon for penetrating armour.
The sling seems to have fallen out of favor as a combat weapon during medieval Europe, probably due to the greatly increased use of armour by medieval armies.
Some numbers for punches and the like:
776lbf approximately = 3452 joule/meter
http://www.straightdope.com/columns/read/2948...quare-inch
http://www.convertunits.com/from/pounds/to/joule/metre
Note: these are measured in pounds which converts to joules per meter -> I am guessing the smaller the surface area per joule the greater the chance of penetration. It looks to me, telling me how many joules is only part of the story, I can use it to tell me when a particular weapon is going to penetrate but it does not help me to compare dissimilar weapons with dissimilar surface areas. I expect just considering the surface area of the weapon is also a great simplification.
| Quote: |
| A study of 70 boxers found elite-level fighters could punch with an average of 776 pounds of force. Another study of 23 boxers showed elite fighters were able to punch more than twice as hard as novices, the hardest hitter generating almost 1,300 pounds of force |
776lbf approximately = 3452 joule/meter
http://www.straightdope.com/columns/read/2948...quare-inch
http://www.convertunits.com/from/pounds/to/joule/metre
Note: these are measured in pounds which converts to joules per meter -> I am guessing the smaller the surface area per joule the greater the chance of penetration. It looks to me, telling me how many joules is only part of the story, I can use it to tell me when a particular weapon is going to penetrate but it does not help me to compare dissimilar weapons with dissimilar surface areas. I expect just considering the surface area of the weapon is also a great simplification.
Really what is probably needed is the amount of joulles needed for multiple weapons vs multiple types of armour.
I.E. Sword cut, axe chop, spear thrust, dagger thrust, sword thrust etc.
I.E. Sword cut, axe chop, spear thrust, dagger thrust, sword thrust etc.
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