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Dan Howard




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PostPosted: Wed 16 Sep, 2015 2:43 pm    Post subject:         Reply with quote

Cs. Norbert wrote:
It depends on what armor, you don't need heavy arrows to defeat good mail,

Of course you do. The primary threat on any battlefield for three thousand years was from spears and arrows. All armour was specifically designed to stop this threat; it doesn't matter whether it was made from plate or mail or lamellar or leather or cloth. Given that mail was the preferred type of armour in almost every metal using culture on the planet for the best part of two millennia it is pretty clear that it was a very good defence against these weapons. In order for an arrow to even have a chance of compromising armour, any armour, the bow needs to be heavy, the arrow needs to be heavy, and it needs to be shot at close range. Your work will be pointless unless you understand how proper armour functions.

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Benjamin H. Abbott




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PostPosted: Thu 17 Sep, 2015 1:22 am    Post subject:         Reply with quote

As far as anybody can tell, Turkish military arrows during the height of Ottoman power were light: something like 320-620 grains. Bertrandon de la Broquière thought Turkish arrows might pierce light mail. It's not at all clear you need a heavy bow and heavy arrows to pierce mail.
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Dan Howard




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PostPosted: Thu 17 Sep, 2015 3:21 am    Post subject:         Reply with quote

They might turn into pigs and fly away too. Why not find a passage written by someone who actually saw Turkish arrows hitting mail? How about Joinville's eyewitness account of Walter of Châtillon's encounter:

"…and whilst the Turks were fleeing before him, they (who shoot as well backwards as forwards) would cover him with arrows. When he had driven them out of the village, he would pick out the arrows that were sticking all over him; and put on his coat-of-arms again… Then, turning round, and seeing that the Turks had come in at the other end of the street, he would charge them again, sword in hand, and drive them out. And this he did about three times in the manner I have described."

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Pieter B.





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PostPosted: Thu 17 Sep, 2015 6:36 am    Post subject:         Reply with quote

I heard someone on this forum or another talk about diminishing returns once you get past the 150 lbs pound mark for longbows. Is it possible I read that here?



PS, Perhaps the effectiveness of armor is demonstrated by the fact that between the age of Chariot warfare and the Scottish wars the archer was never the premier striking arm of armies. In fact a few medieval laws and even the Holy Bible suggest the bow and arrow were the armament of the poor.
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Cs. Norbert




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PostPosted: Thu 17 Sep, 2015 10:12 am    Post subject:         Reply with quote

Quote:
Heavy bows are indeed used to shoot light arrows. People archive velocity and/or distance records by shooting the lightest arrows they can from the heaviest bow they can. The best Turkish flight bows were 150+lbs. Contemporary velocity records come from shooting absurdly light arrows from extremely heavy (180-195lb) compound bows.

The key word here, would be efficiency, the english self bow doesn't have the same efficiency with light arrows, as the turkish composites and the modern recurve. Also, there might be a problem of safety when using arrows that are too light (or maybe more correct would be: arrows not tough enough to withstand the force)! The increase in lb (of english selfbows) from ~150 to 200 wouldn't make a considerable difference in arrow speed and overall range for light arrows, but the increase in lb for recurve composites might give enough difference to be worth, when the purpose is range only. I speculate that, even a small increase in fps would translate to a considerable difference in yards, because, flight arrows have almost a perfect parabolic flight, and after the apex they maintain a low angle of flight (relative to the horizon), because of their weight (relative to gravity). When the purpose is military effectiveness (penetration), a considerable % increase in yards doesn't translate in a considerable % increase in penetration! In conclusion, there is no logical reason to use heavy bows with light arrows when the purpose is penetration (of different materials with different properties like: iron, linen or other textile meshes, flesh and maybe bone)!

[quote... So perhaps Smythe's archers were managing 480 yards with 130-160lb bows and very light arrows.[/quote]
I believe you are right, most probably they used flight arrows and bows of medium weight!

Quote:
Of course you do. The primary threat on any battlefield for three thousand years was from spears and arrows. All armour was specifically designed to stop this threat; it doesn't matter whether it was made from plate or mail or lamellar or leather or cloth. Given that mail was the preferred type of armour in almost every metal using culture on the planet for the best part of two millennia it is pretty clear that it was a very good defence against these weapons. In order for an arrow to even have a chance of compromising armour, any armour, the bow needs to be heavy, the arrow needs to be heavy, and it needs to be shot at close range. Your work will be pointless unless you understand how proper armour functions.

I think I know where I left room for interpretation, when I stated "...you don't need heavy arrows to defeat good mail,". You need at least an above average lb bow with heavy arrows (heavy according to bow lbs), or a heavy bow with "medium" arrow weights (lets say >60g) to generate enough KE (at close range) to penetrate good quality mail, the gamberson beneath and the flesh, enough to cause life threatening wounds! In my defense, there is a continuation of that statement
Quote:
I believe that a tudor period livery arrow(>63.5g) shoot from a very efficient 170 lb MR bow would have good chances to penetrate (at close range) low quality munition breastplate
where I elaborated on what I believe it takes to penetrate armor of that quality! That bow+arrow formula would generate >125J and 63g is not heavy for a 170 lb bow, that is why I stated "you don't need heavy arrows" in that context. Heavy arrows offer a great advantage (regarding military efficiency) because even if they don't penetrate armor, they have enough KE (at longer ranges) to disrupt and severely hinder the enemy (if enough arrows are launched)!

Quote:
As far as anybody can tell, Turkish military arrows during the height of Ottoman power were light: something like 320-620 grains. Bertrandon de la Broquière thought Turkish arrows might pierce light mail. It's not at all clear you need a heavy bow and heavy arrows to pierce mail.

A 125lb turkish warbow would sent a ~35g arrow at >250 fps which would generate over 105J . This might be enough to penetrate mail and inflict a serious wound if my perspective on penetration is correct! Most believe that penetration depth (regardless of material) is more related to momentum than KE (see Dr. Ashby arrow lethality studies). If that is the case then, most of them are right, but only in specific contexts! Since we are talking of armor penetration, a good example would be iron! Iron is ductile, and depending on quality, it has a specific toughness, elasticity and elongation! Suppose we try to penetrate that iron plate with an arrow of x weight and s velocity, the iron sheet would have a reaction time, this would be the speed at which it deforms and transforms the KE into heat and sound (absorbing a good part of the impact KE). If s is not enough to generate a strong impulse over the short period of time that the iron needs to deform, then most of the energy is dissipated, the iron has time to absorb a large part of the KE, and the arrows would make an indentation with a high diameter in the iron sheet! If s is high enough to overcome the speed at which the sheet deforms, than most of the impact energy will be focused on a smaller area (relative to arrow head) and the iron behaves like it is more brittle, thus most of the impact energy is used to penetrate, and the deformation diameter will be much smaller! Different materials have different reaction speeds, so the speed threshold would be different with each material type. For an efficient penetration, the s thershold should be passed, if not, then we need to have a high momentum (higher quantity / longer time vs lover quantity / short time) that a heavy arrow would generate! While you might have and easier time to estimate the necessary ke to penetrate one material type, it would be more complicated when you have to penetrate at the same time multiple different materials, so a high momentum to go with that ke would be preferable!
So the previous example of the 125lb turkish bow, might be enough to penetrate mail and make a serious wound (at close range), but at medium range, the light arrow looses to much KE and momentum, and it might not even hinder the enemy to much (like heavy arrows do), so it might be too late when the enemy is in the arrow efficient range!
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Benjamin H. Abbott




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PostPosted: Thu 17 Sep, 2015 12:18 pm    Post subject:         Reply with quote

Dan Howard wrote:
They might turn into pigs and fly away too. Why not find a passage written by someone who actually saw Turkish arrows hitting mail? How about Joinville's eyewitness account of Walter of Châtillon's encounter:

"…and whilst the Turks were fleeing before him, they (who shoot as well backwards as forwards) would cover him with arrows. When he had driven them out of the village, he would pick out the arrows that were sticking all over him; and put on his coat-of-arms again… Then, turning round, and seeing that the Turks had come in at the other end of the street, he would charge them again, sword in hand, and drive them out. And this he did about three times in the manner I have described."


That's from a few hundred years before Bertrandon de la Broquière's time. Was Walter of Châtillon wearing what de la Broquière would call light mail? I doubt it. Also, as you well know, various sources from around the twelfth century describe Turkish arrows killing warriors through mail (Walter the Penniless, etc.).
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Dan Howard




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PostPosted: Thu 17 Sep, 2015 2:48 pm    Post subject:         Reply with quote

Cs. Norbert wrote:
I think I know where I left room for interpretation, when I stated "...you don't need heavy arrows to defeat good mail,". You need at least an above average lb bow with heavy arrows (heavy according to bow lbs), or a heavy bow with "medium" arrow weights (lets say >60g) to generate enough KE (at close range) to penetrate good quality mail, the gamberson beneath and the flesh, enough to cause life threatening wounds!

This would be sufficient to defeat LIGHT mail. I'm not sure how you define "good" mail" but the heavier weaves are proof against pretty much any threat. The big advantage of plate is that it is lighter than mail. It is lighter than any other kind of armour ever invented. Mail and scale and leather and cloth can all be made completely arrowproof regardless of how heavy the bow is. The problem is that all of these constructions are thicker and more cumbersome than plate.

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Jasper B.




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PostPosted: Thu 17 Sep, 2015 2:55 pm    Post subject:         Reply with quote

I always thought Turkish flight arrows flew a lot further than +-500 yards. (Although flight arrows for distance competition have little to do with arrows used for war).

Most likely a well known source, but still of interest: http://www.atarn.org/islamic/akarpowicz/turkish_bow_tests.htm

J.B.
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Dan Howard




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PostPosted: Thu 17 Sep, 2015 2:56 pm    Post subject:         Reply with quote

Benjamin H. Abbott wrote:
That's from a few hundred years before Bertrandon de la Broquière's time. Was Walter of Châtillon wearing what de la Broquière would call light mail? I doubt it. Also, as you well know, various sources from around the twelfth century describe Turkish arrows killing warriors through mail (Walter the Penniless, etc.).

I agree that ligher variants of mail are more susceptible to arrows, but these variants don't seem to have been worn very often by themselves. They were either worn as patches to fill in gaps left by other types of armour or they were layered underneath other types of armour, including a second layer of mail as a composite defence.

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Cs. Norbert




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PostPosted: Thu 17 Sep, 2015 4:45 pm    Post subject:         Reply with quote

Benjamin H. Abbott wrote:
Dan Howard wrote:
They might turn into pigs and fly away too. Why not find a passage written by someone who actually saw Turkish arrows hitting mail? How about Joinville's eyewitness account of Walter of Châtillon's encounter:

"…and whilst the Turks were fleeing before him, they (who shoot as well backwards as forwards) would cover him with arrows. When he had driven them out of the village, he would pick out the arrows that were sticking all over him; and put on his coat-of-arms again… Then, turning round, and seeing that the Turks had come in at the other end of the street, he would charge them again, sword in hand, and drive them out. And this he did about three times in the manner I have described."


That's from a few hundred years before Bertrandon de la Broquière's time. Was Walter of Châtillon wearing what de la Broquière would call light mail? I doubt it. Also, as you well know, various sources from around the twelfth century describe Turkish arrows killing warriors through mail (Walter the Penniless, etc.).


If we look at Champ Bane Archery Testing (which is full of flaws in calculations and according to some, the mail wasn't reproduced with the best ring diameter) we find the following data:
- see OP for Bane's calculations!
-with 75lb@28" bow, 985gr arrow, efficiency of 90% he calculated Vi (initial velocity) to be 48.19 m/s, using the same formula (see OP), I've concluded that the bow mass mb would be 0.7kg (if the KE coeff stays the same at 0.04, using 0.7mb is the only way you can achieve that arrow speed with that formula) and the resulting KE is 74.1 J,
-the 4 arrow types he used were between 905 and 1150gr, best performer was type 13 at 950gr that generated 73J according to his calculations,
-he concluded that you only need 73J (vs 80 in Williams's tests that would correspond to short bodkin) to penetrate (3 inch) "Riveted Maille (high quality)" "padded with 2 layers of quilted linen stuffed with 1” cotton batting" if you use the type 13 arrow head,
-since Bane's 75lb bow with 950gr arrows performed almost the same as adam karpowicz's turkish bow of the same lb with 1067 gr arrows, we should correct the 90% efficiency to 70% at 9 gr/lb, which translates to 73.6% efficiency at 12.66 gr/lb,
-using 0.736 efficiency in the original formula, we get a KE of 60 J, so apparently you only need 60 J to penetrate "Riveted Maille (high quality)" "padded with 2 layers of quilted linen stuffed with 1” cotton batting" if using type 13 arrow head, and maybe somewhere between 60 to 70J with a short bodkin,
-if we consider the "Riveted Maille (high quality)" to be worst than the one Williams tested, then ~15J difference (80j - average between 60 and 70J) could be considered justified, and it might be possible that you only need between 60 and 80 J to penetrate maille (depending on quality) and light padding, and >100J (with short bodkin) to penetrate high quality maille and a thick gamberson that williams used in his test.
So the turks might have penetrated maille at close range with those "heavy" 620gr arrow, but unless they used heavier arrows, they couldn't manage that at medium range!

Bane also tested those arrows on 1.2 mm plate (probably mild steel 0.1%C, similar to the one Williams tested), and if the 75lb bow really generated 74J, then according to williams's calculations (defeat = 55J x plate thickness ^ 1.6 = 73.7J ) the short bodking should have penetrated 40mm, but it didn't even started to penetrate!.
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Cs. Norbert




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PostPosted: Thu 17 Sep, 2015 5:13 pm    Post subject:         Reply with quote

Dan Howard wrote:
Cs. Norbert wrote:
I think I know where I left room for interpretation, when I stated "...you don't need heavy arrows to defeat good mail,". You need at least an above average lb bow with heavy arrows (heavy according to bow lbs), or a heavy bow with "medium" arrow weights (lets say >60g) to generate enough KE (at close range) to penetrate good quality mail, the gamberson beneath and the flesh, enough to cause life threatening wounds!

This would be sufficient to defeat LIGHT mail. I'm not sure how you define "good" mail" but the heavier weaves are proof against pretty much any threat.

According to williams, the above is more than enough to defeat 2mm of wrought iron plate with less than 2% slag, or more than enough to defeat a high quality maille made from modern steel, backed by a gamberson made from 16 layers of linen!

Quote:
The big advantage of plate is that it is lighter than mail. It is lighter than any other kind of armour ever invented. Mail and scale and leather and cloth can all be made completely arrowproof regardless of how heavy the bow is. The problem is that all of these constructions are thicker and more cumbersome than plate

It's true that they can be made arrow proof, but at the cost of overheating, low mobility and rapid exhaustion from the heavy armor combinations or thickness! I would also imagine that plates between 1mm and 1.5 mm might have been worn in combination with maille by some troops that didn't afford better armor or they weren't of knightly status!
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PostPosted: Thu 17 Sep, 2015 5:55 pm    Post subject:         Reply with quote

Cs. Norbert wrote:
When the purpose is military effectiveness (penetration), a considerable % increase in yards doesn't translate in a considerable % increase in penetration! In conclusion, there is no logical reason to use heavy bows with light arrows when the purpose is penetration (of different materials with different properties like: iron, linen or other textile meshes, flesh and maybe bone)!


Use a lighter arrow, and you get more speed, and less energy (ignoring flexing of the arrow). Use a heavier arrow, and you get more energy (and a lot more momentum), but less speed. So why not use very heavy arrows? Because you want both - more speed gives you a flatter trajectory, less time for the arrow to reach a potentially moving target, and thus better accuracy at short/medium range. If you already have a heavy arrow, going to a super-heavy arrow will give you more energy, but not much more energy, and you'll lose a lot of speed.

The ideal compromise arrow weight depends on the mass of the limbs of the bow. For a historical composite reflex-recurve bow, it's about 30g. Arrows specialised for more energy or more speed should be lighter or heavier, but not too much lighter or heavier. For the composite bow, you see flight arrows of about 20g, and heavy short-range arrows of about 40g. Those are typical weights across Asia, except for the Manchu bow (which is heavy-limbed).

Cs. Norbert wrote:
A 125lb turkish warbow would sent a ~35g arrow at >250 fps which would generate over 105J . This might be enough to penetrate mail and inflict a serious wound if my perspective on penetration is correct! Most believe that penetration depth (regardless of material) is more related to momentum than KE (see Dr. Ashby arrow lethality studies).


For penetration depth into targets where the main force resisting penetration is viscous drag, momentum gives you the penetration depth. For going through steel plates, energy. For a good summary of going through plate, see T. Atkins, The Science and Engineering of Cutting, Elsevier, 2009.

For flexible armour like mail and brigandine, it's even more important to have high speed, because the armour will move if you give it enough time, and your energy will go into giving KE to the armour rather than penetrating the armour.

Trying to shoot through armour needs energy, and big-game hunting needs momentum.

"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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Randall Moffett




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PostPosted: Thu 17 Sep, 2015 7:32 pm    Post subject:         Reply with quote

Quote:
I agree that ligher variants of mail are more susceptible to arrows, but these variants don't seem to have been worn very often by themselves. They were either worn as patches to fill in gaps left by other types of armour or they were layered underneath other types of armour, including a second layer of mail as a composite defence.


I'd love to see evidence of this. We have evidence of higher quality mail worn by the uppers but we do not even know if it was used along or with plate when we find them in many of these accounts.

I admit it seems a likely concept but what direct evidence is there for this over other concepts?

RPM
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Benjamin H. Abbott




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PostPosted: Thu 17 Sep, 2015 9:13 pm    Post subject:         Reply with quote

Here is the full quotation from Bertrandon de la Broquière's Voyage d'Outremer, Galen Kline's 1988 English translation:

Quote:
Because I have talked about light armament, I think that the lightest plate armor or coats of mail would be best, which helmets with wide visors, with light leg armor and shields, for the Turkish arrows, as we know, are not strong, however strong their bows. Their bows are short and their arrows, too, and light. The iron is set into the wood would not sustain a heavy blow. I don't think the arrows would wound unless they strike an unprotected place. In case of necessity, our archers could use the Turkish arrows, but they could not use ours because the notches are too narrow and the strings of their bows are too thick since they are made of gut. Their archers don't shoot from as far away as ours, but when they are shooting close, they are fast and accurate. Because of this, I think that light plate armor and coats of mail are best. I think their bows and arrows might penetrate a light coat of mail.


As you can see, de la Broquière more or less agreed with Dan but thought Turkish arrows could potentially defeat light mail.
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Dan Howard




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PostPosted: Fri 18 Sep, 2015 12:52 am    Post subject:         Reply with quote

Randall Moffett wrote:
I'd love to see evidence of this. We have evidence of higher quality mail worn by the uppers but we do not even know if it was used along or with plate when we find them in many of these accounts.

I admit it seems a likely concept but what direct evidence is there for this over other concepts?

I'm actually working on collecting evidence for this right now. I think I might have enough to make a convincing argument but we'll see.

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PostPosted: Fri 18 Sep, 2015 12:59 am    Post subject:         Reply with quote

Cs. Norbert wrote:
According to williams, the above is more than enough to defeat 2mm of wrought iron plate with less than 2% slag, or more than enough to defeat a high quality maille made from modern steel, backed by a gamberson made from 16 layers of linen!

Williams tested one type of mail out of the hundreds that we have extant. Some of them have weaves that are denser than that tested by WIlliams and others do not. Lighter mail would be more susceptible to arrows and the heavier ones would not. The heaviest ones are completely proof against any kind of bow. One issue with the heavier weaves is that you start to lose flexibility. In some circumstances it is better to wear two layers of light mail rather than one heavy layer because you retain more flexibility. In some hauberks you see dense, heavy links in vulnerable places such as the chest and neck and lighter, more open links in places that are less likely to get hit, such as the back and left side.

It doesn't matter whether it is made of modern steel or not. If you shoot an arrow at 3mm plate, there is no way that it would penetrate regardless of what kind of steel it was. The heaviest types of mail protect just as well as that 3mm plate. One problem is that these kinds of mail are a lot heavier than plate.

Quote:
It's true that they can be made arrow proof, but at the cost of overheating, low mobility and rapid exhaustion from the heavy armor

Overheating has never been a problem with armour - regardless of its weight; it is enclosed helmets that cause heat issues. Mobility and exhaustion are largely irrelevant on horseback. Infantry had to worry about the weigh of armour but cavalry did not. There is a reason why infantry breastplates tend to top out at around 4mm thick while cavalry breastplates went up to 9mm.

Quote:
If we look at Champ Bane Archery Testing (which is full of flaws in calculations and according to some, the mail wasn't reproduced with the best ring diameter) we find the following data:
Ring diameter is the least of the problems with the mail the used. Modern Indian-made riveted mail is completely unsuitable for weapons testing.
http://www.myArmoury.com/talk/viewtopic.php?t=19189

Here are some of the denser weaves of extant mail that are arrowproof.



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Cs. Norbert




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PostPosted: Fri 18 Sep, 2015 4:55 am    Post subject:         Reply with quote

Timo Nieminen wrote:
Cs. Norbert wrote:
When the purpose is military effectiveness (penetration), a considerable % increase in yards doesn't translate in a considerable % increase in penetration! In conclusion, there is no logical reason to use heavy bows with light arrows when the purpose is penetration (of different materials with different properties like: iron, linen or other textile meshes, flesh and maybe bone)!


Use a lighter arrow, and you get more speed, and less energy (ignoring flexing of the arrow). Use a heavier arrow, and you get more energy (and a lot more momentum), but less speed. So why not use very heavy arrows? Because you want both - more speed gives you a flatter trajectory, less time for the arrow to reach a potentially moving target, and thus better accuracy at short/medium range. If you already have a heavy arrow, going to a super-heavy arrow will give you more energy, but not much more energy, and you'll lose a lot of speed.

The ideal compromise arrow weight depends on the mass of the limbs of the bow. For a historical composite reflex-recurve bow, it's about 30g. Arrows specialised for more energy or more speed should be lighter or heavier, but not too much lighter or heavier. For the composite bow, you see flight arrows of about 20g, and heavy short-range arrows of about 40g. Those are typical weights across Asia, except for the Manchu bow (which is heavy-limbed).


For effective hunting you need ranges below 50 yards, and almost pinpoint accuracy, thus the high importance of accuracy which is related to arrow weight (being light translates to a flatter trajectory which is better for accuracy)! When "hunting" knights or well armored infantry that charge in mass, having good accuracy at a very reduced effective range might translate into big trouble (understatement)! For military effectiveness, you need arrows that have a serious effect (even if penetration is not achieved, the momentum is high enough to cause deep deformations in armor) at medium-long ranges (up to 240 yards), if we take for ex. ranges over 100 yards, we cannot talk of pinpoint accuracy, the accuracy the english archer needed, was to anticipate the range at which the enemy will be, when the arrow is close to landing (and we are talking of square meters areas not cm2). Volley shooting doesn't need hunting accuracy! To put things more simply: for heavy bows (over 170lb), a light arrow would be under 5 gr/lb (the quoted statement is used in a context - see previous related discussion- where arrows are lighter than that, probably close to flight arrow weight), which should be close to EWBS standard arrow (52g)! This arrow might be effective (depending on the enemy's level of protection) against armor in ranges between close to medium (effective doesn't necessarily mean armor penetration), considering that, what do you think the english archers should do: use that "light" arrow weight with a heavy bow, at greater ranges, or at medium range with "increased accuracy" (suppose a medium range would be somewhere between 50-100 yards), with decreased efficiency, or use heavier arrows that would be effective up to >200yards and a decrease in accuracy (per square meter)?

It's interesting that, the weight compromise between 20-40g seems to be "ideal" for the recurve-composite, when we have for ex: a 136lb@30" turkish bow (A. Karpowicz) with 1067 gr arrow weight that performs the same as an efficient english MR replica longbow of 175 lb@32" with 980 gr arrows (which doesn't translate to " heavy short-range arrows", in that context)!

Quote:
For penetration depth into targets where the main force resisting penetration is viscous drag, momentum gives you the penetration depth. For going through steel plates, energy. For a good summary of going through plate, see T. Atkins, The Science and Engineering of Cutting, Elsevier, 2009.

For flexible armour like mail and brigandine, it's even more important to have high speed, because the armour will move if you give it enough time, and your energy will go into giving KE to the armour rather than penetrating the armour.

Trying to shoot through armour needs energy, and big-game hunting needs momentum.

For penetration depth into flesh (if this is what you mean when using "targets") you don't have a viscous drag environment, the fluids would help lubrication (not friction) and penetration in flesh! If you are referring to Ashby's research, then you will see that arrow FOC and momentum is for bone penetration (or passing the rib-cage)! Yes momentum does give you a good assurance of penetration depth especially when you need to penetrate multiple environments(or material types at the same time, that is what I was referring to, when I used " penetration (of different materials with different properties like: iron, linen or other textile meshes, flesh and maybe bone)")!
For flexible armor like mail, light and fast arrows aren't the best choice! The penetration mechanics on maille is not the same as in plate, you already have a gap (and an anchor point for the arrow tip), the force you need to penetrate would be a sum of the force needed to expand the ring diameter (too rapid expansion will break the ring) to match the arrow head projected surface, and the force/mm (or cm or inch) to drive the arrow forward after the widest area of the arrow head passed the penetration point. Since maille rings would have a fast reaction time, a good portion of the impact KE will be absorbed, but the depth of deformation will be higher than of plate! Using light and fast arrows you might achieve penetration because the maille expansion times is not sufficient to match the arrow speed, but penetration would be shallow and deformation depth would also be low! Using heavy arrows you achieve a deeper deformation, which results in a higher compression of the tissue and organs, and every unit of penetration will be amplified (even if penetration is not achieved, the deformation length might be enough to severely injure)!
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Randall Moffett




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PostPosted: Fri 18 Sep, 2015 6:52 am    Post subject:         Reply with quote

Dan,

Cannot wait to see it. There are so many types of mail that come up but use is always something I find to be largely left less clear in the records.

Keep me posted. In an very interested in seeing what you have.

RPM
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Timo Nieminen




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PostPosted: Fri 18 Sep, 2015 7:07 am    Post subject:         Reply with quote

Cs. Norbert wrote:
Timo Nieminen wrote:
Cs. Norbert wrote:
When the purpose is military effectiveness (penetration), a considerable % increase in yards doesn't translate in a considerable % increase in penetration! In conclusion, there is no logical reason to use heavy bows with light arrows when the purpose is penetration (of different materials with different properties like: iron, linen or other textile meshes, flesh and maybe bone)!


Use a lighter arrow, and you get more speed, and less energy (ignoring flexing of the arrow). Use a heavier arrow, and you get more energy (and a lot more momentum), but less speed. So why not use very heavy arrows? Because you want both - more speed gives you a flatter trajectory, less time for the arrow to reach a potentially moving target, and thus better accuracy at short/medium range. If you already have a heavy arrow, going to a super-heavy arrow will give you more energy, but not much more energy, and you'll lose a lot of speed.

The ideal compromise arrow weight depends on the mass of the limbs of the bow. For a historical composite reflex-recurve bow, it's about 30g. Arrows specialised for more energy or more speed should be lighter or heavier, but not too much lighter or heavier. For the composite bow, you see flight arrows of about 20g, and heavy short-range arrows of about 40g. Those are typical weights across Asia, except for the Manchu bow (which is heavy-limbed).


For effective hunting you need ranges below 50 yards, and almost pinpoint accuracy, thus the high importance of accuracy which is related to arrow weight (being light translates to a flatter trajectory which is better for accuracy)! When "hunting" knights or well armored infantry that charge in mass, having good accuracy at a very reduced effective range might translate into big trouble (understatement)! For military effectiveness, you need arrows that have a serious effect (even if penetration is not achieved, the momentum is high enough to cause deep deformations in armor) at medium-long ranges (up to 240 yards), if we take for ex. ranges over 100 yards, we cannot talk of pinpoint accuracy, the accuracy the english archer needed, was to anticipate the range at which the enemy will be, when the arrow is close to landing (and we are talking of square meters areas not cm2).


Sure, energy is more important than pinpoint accuracy. Military archery is full of examples of sacrificing accuracy in order to gain more energy.

Also plenty of examples of sacrificing long-range performance, and only focussing on short range archery (e.g., Japanese and Manchu archery). 30-40m and less.

Cs. Norbert wrote:
Volley shooting doesn't need hunting accuracy! To put things more simply: for heavy bows (over 170lb), a light arrow would be under 5 gr/lb (the quoted statement is used in a context - see previous related discussion- where arrows are lighter than that, probably close to flight arrow weight), which should be close to EWBS standard arrow (52g)! This arrow might be effective (depending on the enemy's level of protection) against armor in ranges between close to medium (effective doesn't necessarily mean armor penetration), considering that, what do you think the english archers should do: use that "light" arrow weight with a heavy bow, at greater ranges, or at medium range with "increased accuracy" (suppose a medium range would be somewhere between 50-100 yards), with decreased efficiency, or use heavier arrows that would be effective up to >200yards and a decrease in accuracy (per square meter)?


Yes, the light to heavy arrow range for English warbows is heavier than the light to heavy arrow range for the much lighter-limbed Asian reflex-recurve bows. 50g to 100+ g, vs 20-40g.

The point remains: If you shoot a 10g arrow from a 170lb English warbow (and the arrow survives, and ignoring energy lost in flexing the arrow), the arrow will have a higher speed than a 50g arrow shot from the same bow. And a 400g arrow will have less speed and more energy.

I don't see what your point was. Can you clarify?

Cs. Norbert wrote:
It's interesting that, the weight compromise between 20-40g seems to be "ideal" for the recurve-composite, when we have for ex: a 136lb@30" turkish bow (A. Karpowicz) with 1067 gr arrow weight that performs the same as an efficient english MR replica longbow of 175 lb@32" with 980 gr arrows (which doesn't translate to " heavy short-range arrows", in that context)!


Where does that MR bow efficiency come from? "According to some studies" isn't enough for me to find it.

Historical weights for Turkish/Indian/Korean/Chinese arrows are known, historical weights for English warbow arrows are known. Weights of the bows are known. An English warbow is heavier than an Ottoman/Indian/Korean military bow. So the arrow mass giving a good compromise between speed and energy is different (and heavier).

To look at this properly, it isn't enough to know the efficiency for a single arrow mass; you need to know how the efficiency varies with arrow mass. Karpowicz's test give this. Do you know of similar tests for English warbows? Don't need the efficiency as such; arrow speed vs arrow mass is enough, if the arrow mass varies enough.

Cs. Norbert wrote:
Quote:
For penetration depth into targets where the main force resisting penetration is viscous drag, momentum gives you the penetration depth. For going through steel plates, energy. For a good summary of going through plate, see T. Atkins, The Science and Engineering of Cutting, Elsevier, 2009.

For flexible armour like mail and brigandine, it's even more important to have high speed, because the armour will move if you give it enough time, and your energy will go into giving KE to the armour rather than penetrating the armour.

Trying to shoot through armour needs energy, and big-game hunting needs momentum.

For penetration depth into flesh (if this is what you mean when using "targets") you don't have a viscous drag environment, the fluids would help lubrication (not friction) and penetration in flesh! If you are referring to Ashby's research, then you will see that arrow FOC and momentum is for bone penetration (or passing the rib-cage)!


Not specifically referring to Ashby's tests, but Ashby's tests do show the importance of momentum in penetration into animal tissue. Note also that Ashby shows the importance of viscous drag, with the effect of arrow diameter on penetration depth. Tissue is very much a viscous drag environment. Same thing applies for shooting arrows into water (e.g., in bowfishing). Why does the arrow slow down? The same thing will happen in tissue.

Cs. Norbert wrote:
Yes momentum does give you a good assurance of penetration depth especially when you need to penetrate multiple environments(or material types at the same time, that is what I was referring to, when I used " penetration (of different materials with different properties like: iron, linen or other textile meshes, flesh and maybe bone)")!
For flexible armor like mail, light and fast arrows aren't the best choice! The penetration mechanics on maille is not the same as in plate, you already have a gap (and an anchor point for the arrow tip), the force you need to penetrate would be a sum of the force needed to expand the ring diameter (too rapid expansion will break the ring) to match the arrow head projected surface, and the force/mm (or cm or inch) to drive the arrow forward after the widest area of the arrow head passed the penetration point. Since maille rings would have a fast reaction time, a good portion of the impact KE will be absorbed, but the depth of deformation will be higher than of plate! Using light and fast arrows you might achieve penetration because the maille expansion times is not sufficient to match the arrow speed, but penetration would be shallow and deformation depth would also be low! Using heavy arrows you achieve a deeper deformation, which results in a higher compression of the tissue and organs, and every unit of penetration will be amplified (even if penetration is not achieved, the deformation length might be enough to severely injure)!


Basically, why you want something under your mail when facing high energy arrows.

150J to an unpadded target wouldn't be very nice. That's about the same energy as delivered by beanbag rounds. Beanbag rounds don't tend to severely injure (by design), so that kind of energy spread over a beanbag area isn't so bad, but it does tend to encourage people to stop fighting (which is the point).

If the mail is light enough so that you can penetrate the mail (and the underpadding), then you don't need much energy to do a lot of damage - you've put a sharp arrowhead in flesh. Sure, sometimes just hitting the mail, without penetration, can be better. Mace, club, warhammer might do better than a sword that doesn't penetrate. The questions is how much damage an arrow can do, with the energy left after moving/compressing mail and padding.

"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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Will S




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PostPosted: Fri 18 Sep, 2015 2:08 pm    Post subject:         Reply with quote

Just a point or two - its useless using EWBS flight records in an investigation regarding military penetration etc. The arrows are FLIGHT arrows. Granted they're roughly based on mediaeval arrows but by no means whatsoever are they the same thing. They are simply a piece of modern sporting equipment developed and tweaked by individuals to achieve a long distance when shot.

The "standard" arrow for instance is a concoction dreamt up by a couple of people using whatever they had on hand at the time (this is from a conversation I had with Mark Stretton last week on the matter) and bears almost zero resemblance to a mediaeval arrow.

The only arrow used in EWBS flight records that is worth taking any notice of is the Livery arrow. This is the only one based exactly on extant arrows (from the Mary Rose) along with the Westminster Arrow which is rarely shot in competition. Even then, the arrows used for flight records are the absolute lightest, fastest arrows available within the given specifications.

Also, using draw weights as your primary focus point shows a serious lack of understanding of bows in general. I don't mean to be rude at all, but I can assure you that draw weights are meaningless in this context. One well made 120lb bow will outshoot, outperform and give vastly different results in all of your tests to a badly made 180lb bow.

Add to that the fact that if an archer is shooting a bow at his weight limit, he will almost always be outshot by an archer who is comfortable. That is to say, if "Archer A" is shooting a very well made 160lb bow but finds it difficult to reach full draw, he will always be beaten in distance and performance by "Archer B" shooting a 120lb bow, if Archer B isn't struggling to get to full draw.

This is why your analysis is only touching the absolute surface, and why a better understanding of the shooting and making of heavy warbows is necessary to do tests like these. Otherwise all you're doing is combining written data from numerous sources into one place and trying to produce a result. Written data on bow performance is only useful if you also know exactly the state of the archer, the weather, the humidity, the quality of the bow, the age of the bow, the decrease in performance of the bow since new, the arrow weight, the fletching shape, the arrow quality (how well was it fletched, how thick is the binding) and so on.
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