Sliding weights

fearn · 1st July 2005, 08:29 PM

Hi Jens,

While I like the topic of sliding weights, I can think of a couple of really good reasons why someone would "have a weight" on the back of a claymore. If the weight were _fixed in place_, it could be extremely useful either to tune the center of gravity and center of percussion, or alternately, perhaps to dampen shocks from the blade hitting a target.

While I've never seen such a weight on a sword, I wouldn't be surprised if some enterprising soul didn't try it at some point. Fixing a lead slug (or similar) to a blade would certainly be simpler than remanufacturing the blade to have better performance characteristics.

Anyway, back onto the topic: one suggestion I would make is that a shorter slide would be more useful than a longer one, because the weight could move more quickly. Imagine, for instance, a weight that was on the hilt side of the center of gravity when the sword was upright, but which could be propelled across the center by some wrist action to make the sword tip heavy. Such a sword would be easy to accelerate and would hit hard, although it would be hard to recover after a blow.

Fearn

Jens Nordlunde · 1st July 2005, 09:58 PM

Hi Fearn,

We may, or we may not find swords with sliding weights, but I have a strange feeling, that I have seen one many years ago in a museum, maybe in Istanbul, or somewhere else – I am not sure.

What do you mean by writing that the weight should/could be ‘fixed in place’? How would it dampen he chock?

You write, ‘Fixing a lead slug (or similar) to a blade would certainly be simpler than remanufacturing the blade to have better performance characteristics.’ Yes you are right, that was what the headmen did, if you can believe, that the tree wholes at the blunt tip of their swords were for leaden weights, but they only had to hit once, so why would they need extra weight?

I agree with you, that a short glide would solve quite a lot of possible problems, although the shorter glide, the lesser power. I think I understand what you write next, but I am not quite sure – remember that I’m not brilliant in English. Is it possible for you to explain it in another way? Do I understand you right, when I think that you are saying, that the glider should travel from the back of the blade to the front? If yes, I think this would give the whole thing more force, but I can prove why I think so.

Jens

Montino Bourbon · 1st July 2005, 11:02 PM

actually the weight moving forward would make a longer pendulum, thus slowing it down, I think.

Besides, for the weight to have a real effect it would have to be big enough that it would add too much weight to make the sword useable.

fearn · 2nd July 2005, 01:16 AM

Hi Montino,

You're right, but as I recall, the time of the pendulum works in part on the distance to the center of the pendulum's mass, not just its total length.

With a weight that slides for a long distance down the blade, you're right. The blade gets progressively more tip heavy, meaning that it will take more energy to move the tip and that it will hit harder (transferring more energy).

If the slide is short, around the blade's normal center of mass, what would happen is that the sword would go from back-weighted to front-weighted. Basically, this would mean that the sword accelerated a bit faster from rest (starting out back-weighted, as in a small sword), hit a bit harder (shifting to front-weighted), and was a bit harder to withdraw (still front-weighted). This type of design makes a lot of sense when you're only planning a single blow, as in an executioner's sword. In a battle, I'm not so sure that it's advantageous, but I don't know. We'll have to see what the engineers say.

One thing to remember is that a blade with a slot down the middle is probably more fragile than a solid blade of the same weight. Jens has proposed an interesting question, and it will be interesting to see some numbers around it.

Fearn

Rivkin · 2nd July 2005, 01:30 AM

I truly believe that any sliding weight would be totally cool, fancy, and useless. I see no reasonable advantage over permanent placement of some weight at the sword's end, etc.

Ian · 2nd July 2005, 04:33 AM

This topic is closely akin to the physics of hitting a baseball.

BTW, I notice that the on deck hitter often puts a ring weight around the bat barrel to take some practice swings, but does not try to emulate that weight in the bat itself. It slows down the bat speed and if the bat is overly heavy too much power would be lost -- kinetic energy is proportional to the square of velocity, but only linearly related to mass.

Ian

ariel · 2nd July 2005, 10:59 AM

I remember years ago seeing a Chinese throwing knife that always hit the target with a point and got imbedded quite deeply. Apparantly the secret was a hole drilled within the entire blade along the whole length and filled with mercury. It moved freely in this channel and changed the center of gravity. Was very impressive.
I guess, the same principle as discussed here.

1st July 2005, 08:29 PM	#1
fearn Member Join Date: Dec 2004 Posts: 1,247	Hi Jens, While I like the topic of sliding weights, I can think of a couple of really good reasons why someone would "have a weight" on the back of a claymore. If the weight were _fixed in place_, it could be extremely useful either to tune the center of gravity and center of percussion, or alternately, perhaps to dampen shocks from the blade hitting a target. While I've never seen such a weight on a sword, I wouldn't be surprised if some enterprising soul didn't try it at some point. Fixing a lead slug (or similar) to a blade would certainly be simpler than remanufacturing the blade to have better performance characteristics. Anyway, back onto the topic: one suggestion I would make is that a shorter slide would be more useful than a longer one, because the weight could move more quickly. Imagine, for instance, a weight that was on the hilt side of the center of gravity when the sword was upright, but which could be propelled across the center by some wrist action to make the sword tip heavy. Such a sword would be easy to accelerate and would hit hard, although it would be hard to recover after a blow. Fearn

1st July 2005, 09:58 PM	#2
Jens Nordlunde Member Join Date: Dec 2004 Location: Europe Posts: 2,718	Hi Fearn, We may, or we may not find swords with sliding weights, but I have a strange feeling, that I have seen one many years ago in a museum, maybe in Istanbul, or somewhere else – I am not sure. What do you mean by writing that the weight should/could be ‘fixed in place’? How would it dampen he chock? You write, ‘Fixing a lead slug (or similar) to a blade would certainly be simpler than remanufacturing the blade to have better performance characteristics.’ Yes you are right, that was what the headmen did, if you can believe, that the tree wholes at the blunt tip of their swords were for leaden weights, but they only had to hit once, so why would they need extra weight? I agree with you, that a short glide would solve quite a lot of possible problems, although the shorter glide, the lesser power. I think I understand what you write next, but I am not quite sure – remember that I’m not brilliant in English. Is it possible for you to explain it in another way? Do I understand you right, when I think that you are saying, that the glider should travel from the back of the blade to the front? If yes, I think this would give the whole thing more force, but I can prove why I think so. Jens

1st July 2005, 11:02 PM	#3
Montino Bourbon Member Join Date: Dec 2004 Location: Santa Barbara, California Posts: 301	actually the weight moving forward would make a longer pendulum, thus slowing it down, I think. Besides, for the weight to have a real effect it would have to be big enough that it would add too much weight to make the sword useable.

2nd July 2005, 01:16 AM	#4
fearn Member Join Date: Dec 2004 Posts: 1,247	Hi Montino, You're right, but as I recall, the time of the pendulum works in part on the distance to the center of the pendulum's mass, not just its total length. With a weight that slides for a long distance down the blade, you're right. The blade gets progressively more tip heavy, meaning that it will take more energy to move the tip and that it will hit harder (transferring more energy). If the slide is short, around the blade's normal center of mass, what would happen is that the sword would go from back-weighted to front-weighted. Basically, this would mean that the sword accelerated a bit faster from rest (starting out back-weighted, as in a small sword), hit a bit harder (shifting to front-weighted), and was a bit harder to withdraw (still front-weighted). This type of design makes a lot of sense when you're only planning a single blow, as in an executioner's sword. In a battle, I'm not so sure that it's advantageous, but I don't know. We'll have to see what the engineers say. One thing to remember is that a blade with a slot down the middle is probably more fragile than a solid blade of the same weight. Jens has proposed an interesting question, and it will be interesting to see some numbers around it. Fearn

2nd July 2005, 01:30 AM	#5
Rivkin Member Join Date: Dec 2004 Posts: 655	I truly believe that any sliding weight would be totally cool, fancy, and useless. I see no reasonable advantage over permanent placement of some weight at the sword's end, etc.

2nd July 2005, 04:33 AM	#6
Ian Vikingsword Staff Join Date: Dec 2004 Location: The Aussie Bush Posts: 4,361	This topic is closely akin to the physics of hitting a baseball. BTW, I notice that the on deck hitter often puts a ring weight around the bat barrel to take some practice swings, but does not try to emulate that weight in the bat itself. It slows down the bat speed and if the bat is overly heavy too much power would be lost -- kinetic energy is proportional to the square of velocity, but only linearly related to mass. Ian

2nd July 2005, 10:59 AM	#7
ariel Member Join Date: Dec 2004 Location: Ann Arbor, MI Posts: 5,503	I remember years ago seeing a Chinese throwing knife that always hit the target with a point and got imbedded quite deeply. Apparantly the secret was a hole drilled within the entire blade along the whole length and filled with mercury. It moved freely in this channel and changed the center of gravity. Was very impressive. I guess, the same principle as discussed here.