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Vincent Le Chevalier
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 Posted: Thu 28 Jan, 2010 8:16 am Post subject: |
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OK, there seems to be a significant amount of evidence to the fact that harming someone with a sword through mail+gambison is unlikely... I surrender 
So, that means that the forward-balanced blades were so just to increase cutting power, not blunt impact, though it is a side effect. And also, that the straight blade was chosen for its versatility, not really its marginally increased impact.
| Aleksei Sosnovski wrote: | | But ultimately I think that the question of hitting or not hitting armor with a sword is somewhat not related to real life. One can and should try to hit his opponent into places not covered with armor. And one should avoid needlessly dulling his sword. But when being hit, one's opponents will do their best to get hit in the least dangerous places, i.e. places covered with armor. So whether one wants to hit maille with his precious sword or not, he will most likely anyway do it if he faces maille-clad opponents. Same goes for helmets and other armor pieces. |
That's more or less what I was getting at, but I thought that the blunt impact through armour might have influenced the outcome of the fight, so that blades more capable of blunt impact were selected to fight when flexible armour was dominant. It seems not...
Regards,
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Vincent
Ensis Sub Caelo
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P. Cha
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| Posted: Fri 29 Jan, 2010 10:50 am Post subject: |
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| Aleksei Sosnovski wrote: |
And let's not forget that most swords in middle ages were total crap compared to modern reproductions like Albion swords. Take a sword with edge hardness around 40 HRC (an excellent sword for 11-14 century and a good sword for 15-16 century) and let somebody deflect your blow with similar sword, or, even worse, stop your blade with the flat of his blade. Your sword will get dull in the place of impact. I've done this, so I know. Same will happen if you hit a helmet. So I am pretty skeptic about all these videos where people effortlessly cut things with razor-sharp blades. However I am not saying that swords should be dull, because in a battle they will stay sharp for at least some time, and in a duel one might even get away without seriously dulling his blade. And, of course, there always are and have been people obsessed with sharpness. And there were some really good swords that could withstand rigors of battle much better than an average blade too. However when learning to cut, and especially doing some test cutting in order to understand what a medieval sword can do, one should try both sharp and dull blades. Because that is what a warrior would most likely have in a real life: a sharp blade at the beginning of the fight, and a dull blade, maybe even nicked so badly that it looks more like a saw, at the end. And still a warrior would have to kill his opponents, one way or another. |
I´m not so sure about your assessment of the quality of historical swords. Yes there were some that were crap compared to modern swords...but there were some that were BETTER then modern swords. A knight in the days of old wouldn´t have been very impressed with an albion sword...what he would be impressed with his how consistent albion swords were when he ordered 100 of them for his men at ams.
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Michael Edelson
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| Posted: Fri 29 Jan, 2010 12:24 pm Post subject: |
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I just want to add something about sword rigidity edge to edge. It may not be scientific, but it might help.
I'v recently broken a blunt trainer on a pell and have had to switch to using a waster. My hands are killing me. I feel every blow. With the blunt steel sword, despite the fact that I hit with proper edge alignment, the blow was substantially cushioned. In theory there may not be any flex edge to edge, but in practice there is quite a bit.
New York Historical Fencing Association
www.newyorklongsword.com
Byakkokan Dojo
http://newyorkbattodo.com/
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Aleksei Sosnovski
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| Posted: Fri 29 Jan, 2010 12:57 pm Post subject: |
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| P. Cha wrote: |
but there were some that were BETTER then modern swords.
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Could you please refer to a specific source that your assumption is based on? There is an article on this site that has some data on quality of medieval blades: http://www.myArmoury.com/feature_bladehardness.html It gives some idea about average blade hardness. I also remember a sword made of iron (= no heat treatment possible) in works of Kirpichnikov. And sagas mention swords being blunted by shiled bosses, bending during battle, etc. But hardness is not the only thing that matters. There is a big difference between modern alloy steel quenched in molten salt and and medieval carbon steel with a lot of slack inclusion and other imperfections slack quenched. And while there MIGHT have been swords that were actually better than Albions (mainly because of being constructed of several types of steel so that the edge could be harder while the core could be softer and more resilient, or being made of some exotic materials like wootz steel) this was certainly not the norm. We are speaking about MOST of the swords a medieval warrion would face on the battlefield, not about the best ones.
Well, I mentioned 40 HRC in my previous post. I think I need to correct myself and increase it to 45 HRC. A hardnes of a spring and hardness of (at least some of the) swords I made. And supposedly the hardness of the sword I tested (unfortunately I do not have the tools to measure the hardness of the blade, but it was quenched by a professional heat treater and I asked him to temper it to 45 HRC). But I state it again: we tend to make or conclusions based on performance of the best pieces ever created, not on the performance of an average piece. It is like judging about performance of an average car by the performance of Ferrari or even that of an F1 bolid.
| Michael Edelson wrote: | I just want to add something about sword rigidity edge to edge. It may not be scientific, but it might help.
I'v recently broken a blunt trainer on a pell and have had to switch to using a waster. My hands are killing me. I feel every blow. With the blunt steel sword, despite the fact that I hit with proper edge alignment, the blow was substantially cushioned. In theory there may not be any flex edge to edge, but in practice there is quite a bit. |
Unfortunately I could not understand what you are talking about. Are you stating that sharp and blunt swords bend differently in edge-to-edge direction? Or that they both actually do bend at this direction?
There is not much difference between a sharp and a blunt blade. I even dare to say that a blunt sword is (VERY SLIGHTLY) more rigid because it has more metal on its edges (think of an I-beam and you'll get the idea of what I am talking about). What really matters is the width of the blade. I have a sharp sword that evenly tapers in width from about 1,25" at the base to about 0.8 " or even les at the tip. And when I hit a hard object with it I feel that the blade bends quite a lot. Wide blades bend edge-to-edge so little that it can be neglected. However they do bend flat-to-flat even if you strike with an ideal edge alignment, and that is what you might feel.
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Timo Nieminen
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| Posted: Fri 29 Jan, 2010 1:22 pm Post subject: |
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| Michael Edelson wrote: | I just want to add something about sword rigidity edge to edge. It may not be scientific, but it might help.
I'v recently broken a blunt trainer on a pell and have had to switch to using a waster. My hands are killing me. I feel every blow. With the blunt steel sword, despite the fact that I hit with proper edge alignment, the blow was substantially cushioned. In theory there may not be any flex edge to edge, but in practice there is quite a bit. |
Not necessarily anything to do with flex. Whether there is force acting back on your hands depends on the balance, weight, and moment of inertia of the sword - hit at the CoP and there will be no force on your hand, even with an infinitely rigid sword.
One way to test the effect of flex of a steel blade on the force back on the hand is to compare hitting with flat vs hitting with edge. Hit with the same speed and power, and the same motion, with the only difference being the blade being turned by 90 degrees. The CoP won't care about the turn, but the flex will care very much.
Assuming one does this at lower speed than a normal edge-on strike, the motion, including the hand and arm, should be kept as similar as possible.
Flex will, more or less, scale as the inverse of the thickness squared. For a waster, with a ratio of width:thickness of 2 or even less, there's only a factor of 4 difference between the flex in the plane of the edge, and in the direction of the flat. A ratio of 10:1 in size, so for flexibility 1:100, is common enough for steel. So a waster rigid enough in the plane of the blade is stiff sideways, not necessarily for steel. (People say the Cold Steel poly waster is nicely flexible sideways; it also flexes a lot in the plane of the blade compared to steel or wood. Not too much, but you wouldn't want much more.)
A direct measurement of flex under a given load would be unambiguous. Hard to measure if small.
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Bill Grandy
myArmoury Team
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| Posted: Fri 29 Jan, 2010 1:50 pm Post subject: |
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| Aleksei Sosnovski wrote: | | There is an article on this site that has some data on quality of medieval blades: http://www.myArmoury.com/feature_bladehardness.html It gives some idea about average blade hardness. I also remember a sword made of iron (= no heat treatment possible) in works of Kirpichnikov. And sagas mention swords being blunted by shiled bosses, bending during battle, etc. But hardness is not the only thing that matters. There is a big difference between modern alloy steel quenched in molten salt and and medieval carbon steel with a lot of slack inclusion and other imperfections slack quenched. And while there MIGHT have been swords that were actually better than Albions (mainly because of being constructed of several types of steel so that the edge could be harder while the core could be softer and more resilient, or being made of some exotic materials like wootz steel) this was certainly not the norm. We are speaking about MOST of the swords a medieval warrion would face on the battlefield, not about the best ones. |
Here's some food for thought. Dr. Lee Jones, at the last Chivalric Weekend, brought a medieval sword (I believe 13th century, but I could be mistaken) that was steel, and yet had no heat treatment on it whatsoever. Despite that, he also brought up many examples of tools from the exact same time period that showed a wide variety of heat treatments dependent on the purpose of the tool.
In other words, many of these swords *could* have been heat treated to be harder, but the smiths specifically choose not to for whatever reason. With that in mind, I don't know if we can say these swords were necessarily better or worse than their modern counterparts.
HistoricalHandcrafts.com
-Inspired by History, Crafted by Hand
"For practice is better than artfulness. Your exercise can do well without artfulness, but artfulness is not much good without the exercise.” -anonymous 15th century fencing master, MS 3227a
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Vincent Le Chevalier
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| Posted: Fri 29 Jan, 2010 1:54 pm Post subject: |
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| Timo Nieminen wrote: | | Michael Edelson wrote: | I just want to add something about sword rigidity edge to edge. It may not be scientific, but it might help.
I'v recently broken a blunt trainer on a pell and have had to switch to using a waster. My hands are killing me. I feel every blow. With the blunt steel sword, despite the fact that I hit with proper edge alignment, the blow was substantially cushioned. In theory there may not be any flex edge to edge, but in practice there is quite a bit. |
Not necessarily anything to do with flex. Whether there is force acting back on your hands depends on the balance, weight, and moment of inertia of the sword - hit at the CoP and there will be no force on your hand, even with an infinitely rigid sword. |
That's true, with the provision that given his interests Michael is probably using a longsword. With a longsword you'll always get some shock in either hand, because the CoP of each hand is at a different place...
Depending on the pell, another reason why you could get more shock with a wooden waster is that it does not damage the target as much. Remember, any energy that is not dissipated by damaging the target (or sword) is coming back to your hands eventually... This also means that you won't get the same behaviour exactly by hitting with the flat or edge on something that can be cut. If you strike with the edge the impact is inelastic, if you strike with the flat it is elastic. In the latter case it will be much more difficult with the flat because the sword bounces back, forcing you to struggle to keep control even if you hit at CoP.
And yet another possibility is that the steel blunt was sort of "buckling", and flexed on the flat-to-flat plane even though the edge alignment was good. This happens if the impact is not square on target. Actually this would also happen with a sharp sword on armour, so it's something to keep in mind as well.
Regards,
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Vincent
Ensis Sub Caelo
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Luka Borscak
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| Posted: Fri 29 Jan, 2010 2:33 pm Post subject: |
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| Bill Grandy wrote: | | Aleksei Sosnovski wrote: | | There is an article on this site that has some data on quality of medieval blades: http://www.myArmoury.com/feature_bladehardness.html It gives some idea about average blade hardness. I also remember a sword made of iron (= no heat treatment possible) in works of Kirpichnikov. And sagas mention swords being blunted by shiled bosses, bending during battle, etc. But hardness is not the only thing that matters. There is a big difference between modern alloy steel quenched in molten salt and and medieval carbon steel with a lot of slack inclusion and other imperfections slack quenched. And while there MIGHT have been swords that were actually better than Albions (mainly because of being constructed of several types of steel so that the edge could be harder while the core could be softer and more resilient, or being made of some exotic materials like wootz steel) this was certainly not the norm. We are speaking about MOST of the swords a medieval warrion would face on the battlefield, not about the best ones. |
Here's some food for thought. Dr. Lee Jones, at the last Chivalric Weekend, brought a medieval sword (I believe 13th century, but I could be mistaken) that was steel, and yet had no heat treatment on it whatsoever. Despite that, he also brought up many examples of tools from the exact same time period that showed a wide variety of heat treatments dependent on the purpose of the tool.
In other words, many of these swords *could* have been heat treated to be harder, but the smiths specifically choose not to for whatever reason. With that in mind, I don't know if we can say these swords were necessarily better or worse than their modern counterparts. |
Is there a possibility that such steel swords with no heat treatment were ritually killed with annealing? Or that practice was gone by then...
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Timo Nieminen
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| Posted: Fri 29 Jan, 2010 2:39 pm Post subject: |
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| Vincent Le Chevalier wrote: | | Timo Nieminen wrote: | | Michael Edelson wrote: | I just want to add something about sword rigidity edge to edge. It may not be scientific, but it might help.
I'v recently broken a blunt trainer on a pell and have had to switch to using a waster. My hands are killing me. I feel every blow. With the blunt steel sword, despite the fact that I hit with proper edge alignment, the blow was substantially cushioned. In theory there may not be any flex edge to edge, but in practice there is quite a bit. |
Not necessarily anything to do with flex. Whether there is force acting back on your hands depends on the balance, weight, and moment of inertia of the sword - hit at the CoP and there will be no force on your hand, even with an infinitely rigid sword. |
That's true, with the provision that given his interests Michael is probably using a longsword. With a longsword you'll always get some shock in either hand, because the CoP of each hand is at a different place...
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No, you can still have no shock with a two-handed grip. Consider using a longsword one-handed. Strike a pell, and there will be no force acting on the rear hand (because it isn't there); any force back on the hand will be on the front hand. Now hit at the CoP, and there is no force back on the front hand either. If the back hand is lightly touching the grip, there won't be any force either. As long as the motion of the sword is the same, there will be no force on the grip at all - when striking at the CoP, the impact alone provides all the torque required to stop the rotation of the blade, and this same force that gives this torque also stops the linear motion of the sword.
That said, it's an approximation to assume that the grip is the pivot point of the motion of the sword - OK for some strikes with a one-handed sword, but a two-handed grip? (I want to balance a spear for cutting - where is the pivot point of a spear? I've been waiting for the weather to improve a bit to experiment on this. A ball-park figure for the mass of an optimum spear butt, mount and try it, that's the plan.)
As for where the energy goes, yes, that's important. Also how quickly energy is returned - return quickly, high force, return over a longer time, lower force.
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Vincent Le Chevalier
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| Posted: Fri 29 Jan, 2010 3:10 pm Post subject: |
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| Timo Nieminen wrote: | | Vincent Le Chevalier wrote: | | With a longsword you'll always get some shock in either hand, because the CoP of each hand is at a different place... |
No, you can still have no shock with a two-handed grip. Consider using a longsword one-handed. Strike a pell, and there will be no force acting on the rear hand (because it isn't there); any force back on the hand will be on the front hand. Now hit at the CoP, and there is no force back on the front hand either. If the back hand is lightly touching the grip, there won't be any force either. As long as the motion of the sword is the same, there will be no force on the grip at all - when striking at the CoP, the impact alone provides all the torque required to stop the rotation of the blade, and this same force that gives this torque also stops the linear motion of the sword. |
OK, let's break this down a bit...
What causes the shock is that the sword abruptly changes its speed relative to the hand. Of course if you're letting go of the sword with either hand, it feels no shock, but I wouldn't call that a two-handed grip.
The only point of the sword whose speed does not change is the CoP of the impact point. That's probably somewhere on the handle, but still it's only one point, so if the hands are appart from one another at least one of these is going to see the speed change and feel impact (assuming that both hands actually grip the sword). After that there is a matter of degree of course. Generally for a two-handed cut you feel a distinct kick in the fingers of the left hand unless you strike very far up the blade towards the hilt. I find myself trying to minimize the impact on the lead hand because it is the hand used I use for control most, and I don't want to lose it because of the impact.
Now, your last sentence refers to the fact that if the impact happens at the CoP associated to the center of rotation of the sword (and the impact is inelastic) the motion of the sword will just stop. That's true but irrelevant to the impact felt in the hands. Even if one of the hands was the center of rotation, the other one is not and so it will feel a sharp change in motion as the sword stops moving abruptly.
Regards,
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Vincent
Ensis Sub Caelo
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Timo Nieminen
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| Posted: Fri 29 Jan, 2010 4:41 pm Post subject: |
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| Vincent Le Chevalier wrote: | | Timo Nieminen wrote: | | Vincent Le Chevalier wrote: | | With a longsword you'll always get some shock in either hand, because the CoP of each hand is at a different place... |
No, you can still have no shock with a two-handed grip. Consider using a longsword one-handed. Strike a pell, and there will be no force acting on the rear hand (because it isn't there); any force back on the hand will be on the front hand. Now hit at the CoP, and there is no force back on the front hand either. If the back hand is lightly touching the grip, there won't be any force either. As long as the motion of the sword is the same, there will be no force on the grip at all - when striking at the CoP, the impact alone provides all the torque required to stop the rotation of the blade, and this same force that gives this torque also stops the linear motion of the sword. |
OK, let's break this down a bit...
What causes the shock is that the sword abruptly changes its speed relative to the hand. Of course if you're letting go of the sword with either hand, it feels no shock, but I wouldn't call that a two-handed grip.
The only point of the sword whose speed does not change is the CoP of the impact point. That's probably somewhere on the handle, but still it's only one point, so if the hands are appart from one another at least one of these is going to see the speed change and feel impact (assuming that both hands actually grip the sword). After that there is a matter of degree of course. Generally for a two-handed cut you feel a distinct kick in the fingers of the left hand unless you strike very far up the blade towards the hilt. I find myself trying to minimize the impact on the lead hand because it is the hand used I use for control most, and I don't want to lose it because of the impact.
Now, your last sentence refers to the fact that if the impact happens at the CoP associated to the center of rotation of the sword (and the impact is inelastic) the motion of the sword will just stop. That's true but irrelevant to the impact felt in the hands. Even if one of the hands was the center of rotation, the other one is not and so it will feel a sharp change in motion as the sword stops moving abruptly. |
The only point on the sword that doesn't change speed is the centre of rotation, the pivot point. Assuming that the motion of the sword can be described as a simple rotation about a point, which isn't always the case, but at the time of striking, if the blade is moving straight into the target, close enough. This is the case even if the pivot point of the motion isn't on the sword at all.
If the impact is at the CoP for this pivot point, then the sword will uniformly slow its rotation about the pivot point, with no other forces. If you get a force acting back on your hands in this case, it isn't the sword pushing into your hands, it's your hands pushing into the sword. Of course, a hand not gripping at the pivot point will want to continue moving, and will push into the grip unless stopped by the muscles of the arm. So this is distinct from the shock felt at the grip when striking away from the CoP, where even if the hand is stationary, the sword will smack back. As for practical difference, well, that's another matter - force on the hand is force on the hand, either way.
If the moving hand exerts a force on the sword in this way, this will affect the motion of the sword, and if striking at the CoP, will also result in a force on the other hand even if it is stationary (assuming the motion remains a rotation about the original pivot point). Perhaps one feels the least force back striking away from the CoP, so that the impact force and the force of the moving hand, acting together, stop the sword. From sports research, this looks to be the case, even with a one-handed grip - the least shock is felt striking away from the CoP.
Still, the hands aren't moving that fast; even a hand not on the pivot point isn't that far from it. Plus, when you know what the sword will do, your hand can follow it. With a one-handed sword, try hitting with minimal rotation of the sword, striking at the point of balance/centre of mass. You can't get further from the pivot point than that, and you get about the quickest slow-down of the hand you can get with a one-handed sword. Compare with force felt on hand when striking with a rotating-about-stationary-hand blow, hitting away from the CoP.
The physics is simple, but the human holding the sword is not. Time to make a new pell and play around, when the weather is less oppressively hot and humid.
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Aleksei Sosnovski
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| Posted: Fri 29 Jan, 2010 5:13 pm Post subject: |
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| Bill Grandy wrote: |
In other words, many of these swords *could* have been heat treated to be harder, but the smiths specifically choose not to for whatever reason. With that in mind, I don't know if we can say these swords were necessarily better or worse than their modern counterparts. |
There are a lot of possibilities.
1) Maybe it was annealed after its useful life (for example was dropped in a burning house).
2) How much carbon content did the sword have? There is no use in heat treating steel with less than 0.3% carbon. Maybe the bladesmith knew this? If a sword is made of steel with low carbon content, heat treating will actually make it softer by nullifying effects of work hardening.
3) Maybe an attempt was made ta slack quench it, but without any success?
4) Quenching a chisel or a file is MUCH easier than quenching a blade. Especially if one does not know the proper heat treatment process. And a bent sword is much better than a broken one. I made some armor pieces of quenchable steels, but I cannot properly heat treat them because I do not have required equipment and companies that do have such equipment ask too much for their work. Therfore I experimented with different processes and materials including using steels with relatively low carbon content (0.3-0.35%) that can benefit from quenching but do not require tempering and slack quenching of high-carbon steels. And the main rule I follow is "If not sure-make it softer. If it will dent-too bad. But still much better than if it breaks".
5) Soft swords are still quite usable. I used them when I had neither money to buy a proper sword nor knowledge to make one 
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Michael Edelson
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| Posted: Fri 29 Jan, 2010 5:19 pm Post subject: |
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| Aleksei Sosnovski wrote: |
| Michael Edelson wrote: | I just want to add something about sword rigidity edge to edge. It may not be scientific, but it might help.
I'v recently broken a blunt trainer on a pell and have had to switch to using a waster. My hands are killing me. I feel every blow. With the blunt steel sword, despite the fact that I hit with proper edge alignment, the blow was substantially cushioned. In theory there may not be any flex edge to edge, but in practice there is quite a bit. |
Unfortunately I could not understand what you are talking about. Are you stating that sharp and blunt swords bend differently in edge-to-edge direction? Or that they both actually do bend at this direction?
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A waster is a wooden sword. I switched from steel to wood and there is substantially more shock with wood. I never even noticed any shock with steel.
New York Historical Fencing Association
www.newyorklongsword.com
Byakkokan Dojo
http://newyorkbattodo.com/
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Michael Edelson
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| Posted: Fri 29 Jan, 2010 5:24 pm Post subject: |
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| Timo Nieminen wrote: | | Michael Edelson wrote: | I just want to add something about sword rigidity edge to edge. It may not be scientific, but it might help.
I'v recently broken a blunt trainer on a pell and have had to switch to using a waster. My hands are killing me. I feel every blow. With the blunt steel sword, despite the fact that I hit with proper edge alignment, the blow was substantially cushioned. In theory there may not be any flex edge to edge, but in practice there is quite a bit. |
Not necessarily anything to do with flex. Whether there is force acting back on your hands depends on the balance, weight, and moment of inertia of the sword - hit at the CoP and there will be no force on your hand, even with an infinitely rigid sword. |
I rarely hit with the CoP when doing pell work. Perhaps factors other than flex were invovled, but I don't think so. An impact with a sword is never exactly dead on edge to edge, and if it is, it doesn't stay that way. Even in a tatami cut where the edge alignment is perfect, force is often exerted in other directions causing flex. Watch a slow motion video of a cut with a longsword and you will see blade flex. Not edge to edge flex, but the normal kind. In every cut.
This is yet another reason why I'm not a big believer in blunt force sword trauma.
New York Historical Fencing Association
www.newyorklongsword.com
Byakkokan Dojo
http://newyorkbattodo.com/
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Timo Nieminen
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| Posted: Sat 30 Jan, 2010 1:05 am Post subject: |
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| Michael Edelson wrote: |
I rarely hit with the CoP when doing pell work.
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I must ask: why?
As for the rest, of course there must be flex; the only question is whether or not the flex affects the force on the hands. This depends on how quickly the blade flexes to maximum flex, and returns, which in turn depends on how much force is needed to bend the blade. I haven't hit a pell with intent to look at this. Bending blades sideways past their elastic limit on tatami is a pretty standard trick - I have to see what I have that I'm prepared to hit flat on a pell.
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Michael Edelson
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| Posted: Sat 30 Jan, 2010 8:02 am Post subject: |
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| Timo Nieminen wrote: | | Michael Edelson wrote: |
I rarely hit with the CoP when doing pell work.
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I must ask: why? |
Measure.
To strike with the COP, you're giving up about a foot of measure, which means you have to get a foot closer before striking. If you try to do that, you put yourself into close measure without attacking me, which is a bad, bad no no.
| Quote: | | As for the rest, of course there must be flex; the only question is whether or not the flex affects the force on the hands. This depends on how quickly the blade flexes to maximum flex, and returns, which in turn depends on how much force is needed to bend the blade. I haven't hit a pell with intent to look at this. Bending blades sideways past their elastic limit on tatami is a pretty standard trick - I have to see what I have that I'm prepared to hit flat on a pell. |
I hit a pell for about four hours a week, and I'd say, yes.
What does maximum flex have to do with anything? It is not necessary to reach maximum flex to cushion the hands.
New York Historical Fencing Association
www.newyorklongsword.com
Byakkokan Dojo
http://newyorkbattodo.com/
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Vincent Le Chevalier
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| Posted: Sat 30 Jan, 2010 8:25 am Post subject: |
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| Timo Nieminen wrote: | | The only point on the sword that doesn't change speed is the centre of rotation, the pivot point. Assuming that the motion of the sword can be described as a simple rotation about a point, which isn't always the case, but at the time of striking, if the blade is moving straight into the target, close enough. This is the case even if the pivot point of the motion isn't on the sword at all. |
I was speaking of what happens during the impact. Assuming the impact duration is very short, there is only one point on the sword whose speed will be exactly the same before and after the impact, it is the CoP associated to the impact point. If a hand is exactly at that point, it feels no shock. If the hand is elsewhere, the handle of the sword will kick into it one way or another. For short impacts there is no way your muscles are going to anticipate this and change the motion of the hand as fast as the motion of the handle changes, and even if they could it may not be what you want. Far easier to let the impact forces do the work...
This is unrelated to the motion of the sword before or after the impact. It's the change of this motion that causes impact to the hands.
Michael,
From what I know about the balance of wooden swords, if you strike near the tip with one of these you'll have a lot more of the impact forces coming back in your hands than with a properly balanced blunt, without even considering flexibility. I'm not saying flexibility does not come into play at all but what matters for the discussion of blunt trauma is not what is felt in the hands but what is felt by the target... And with different mass repartitions you could have roughly the same impact on target but not the same on the hands.
Regards,
--
Vincent
Ensis Sub Caelo
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Michael Edelson
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| Posted: Sat 30 Jan, 2010 9:37 am Post subject: |
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| Vincent Le Chevalier wrote: |
Michael,
From what I know about the balance of wooden swords, if you strike near the tip with one of these you'll have a lot more of the impact forces coming back in your hands than with a properly balanced blunt, without even considering flexibility. I'm not saying flexibility does not come into play at all but what matters for the discussion of blunt trauma is not what is felt in the hands but what is felt by the target... And with different mass repartitions you could have roughly the same impact on target but not the same on the hands.
Regards, |
This is true. However, my point re blunt force was that there IS substantial flex even on edge to edge oriented strikes, so the elastic properties of steel make swords poorly suited as intruments of blunt force traume.
New York Historical Fencing Association
www.newyorklongsword.com
Byakkokan Dojo
http://newyorkbattodo.com/
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Timo Nieminen
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| Posted: Sat 30 Jan, 2010 2:45 pm Post subject: |
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| Michael Edelson wrote: | | Timo Nieminen wrote: | | Michael Edelson wrote: |
I rarely hit with the CoP when doing pell work.
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I must ask: why? |
Measure.
To strike with the COP, you're giving up about a foot of measure, which means you have to get a foot closer before striking. If you try to do that, you put yourself into close measure without attacking me, which is a bad, bad no no.
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Thanks. Sounds like a good thing to try on tatami, too. Tatami in a shirt or pants even.
| Michael Edelson wrote: |
| Quote: | | As for the rest, of course there must be flex; the only question is whether or not the flex affects the force on the hands. This depends on how quickly the blade flexes to maximum flex, and returns, which in turn depends on how much force is needed to bend the blade. I haven't hit a pell with intent to look at this. Bending blades sideways past their elastic limit on tatami is a pretty standard trick - I have to see what I have that I'm prepared to hit flat on a pell. |
I hit a pell for about four hours a week, and I'd say, yes.
What does maximum flex have to do with anything? It is not necessary to reach maximum flex to cushion the hands. |
The sword will flex on each blow, each time there will be a maximum amount of flex for the particular blow. The only thing this has to do with the maximum flex possible for the sword is you want it to be less, much less.
(More long-winded response follows, also with some thoughts on importance of flex on blunt trauma.)
The force exerted by the sword depends on how quickly it stops. An infinitely rigid sword hitting an infinitely rigid target would result in infinite force. Not realistic, of course. The force is always spread out over some finite time, and the time taken for the sword to reach maximum flex (and return, so about twice this time) is the minimum time over which the force is spread. Thus, it limits the force exerted on the target, and also limits the force back on your hands. The force exerted on your hands will also be limited by the elasticity of the grip, and the glove. Also the skin, if considering the effect deeper within the hand.
The time taken to reach the maximum flex and return depends on how large the flex is, and how fast the blade is moving at impact.
Since there isn't that much padding on the hand, perhaps it matters. Spending time on a pell, even a small difference can matter over that time. Still, I don't believe that your original observation says anything definite about the effect of elasticity. Yes, the difference in elasticity of a metal blade and a waster will make a difference. But the difference in weight and balance will also make a difference. If potential causes A and B can result in effect C, observing C doesn't tell you that A caused the major part of C. As you noted, it wasn't a scientific test, and this is the main unscientific-ness of it. Without any other potential causes, it would be useful, even if unquantitative.
A sword blow will deliver a certain amount of energy to the target. To cut (without slicing) needs pressure - the edge is pushed into the target, against the resistance of the target material. This needs to be done before the target is pushed out of the way (if the target gives, this spreads the delivery of the force over a longer time, reducing the force). Two ways to increase the pressure are to increase the force by delivering said energy faster, and to exert this force over as narrow a blade as possible: speed and sharpness. You can also deliver more energy to the target, but if this is at the cost of speed, you can reduce the cutting ability. Add to that the need to deliver the energy that is delivered to a target that will try to protect itself, and you're not going to optimise the weapon to deliver maximum energy. (But increasing energy until diminishing returns result is good.)
Blunt trauma, OTOH, is largely about energy, and energy delivered deep into the target. A sword is designed to deliver energy quickly, not to deliver lots of energy. But the sword can't deliver energy quickly to an armoured target - the time taken to move the armour and padding, and compress the padding (and skin and superficial tissue of the target, since you're interested in doing serious damage, not just shallow bruises) spreads out the time over which the force is applied.
If this time is large compared to the time taken to flex the blade on the strike, this will be the dominant effect, and the effect of hitting with a real (i.e., flexible) sword and an ideal infinitely rigid sword would be about the same. If the flexing time is long compared to this, then the flex-time is the most important factor. Hard to say very much without having some idea of what this time is. It's same point as shock on the hand - given multiple possible contributing factors, you can't single one out as "the" factor, without further information.
Note that the flexibility of a sword will not reduce the amount of energy delivered, it will reduce the force by increasing the effective impact time. Changing the force will also affect how much of the energy goes into destruction of the target, and how much goes into elastic deformation and displacement. Again, why speed matters when cutting, but the time-scale when considering blunt trauma instead of cutting is much longer.
Sorry if this seems overly pedantic and theoretical, but hastily chosen "scientific" explanations are responsible for lots of misinformation relating to swords (e.g., the various "blood groove" stories). Why encourage?
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