Sliding weights

fearn · 3rd July 2005, 03:03 PM

Hi Jens,

This is getting a bit off subject, but I was partially thinking of atlatls when I was talking about weights absorbing shock in a sword.

The other source of inspiration was a dha-style sword I made out of a machete. I very quickly learned that there were only two good handholds on the long handle: at the end, and about 1/4 of the length from pommel to tip. This was because the sword flexed on impact, and holding it at other points was a recipe for getting a very sore hand (the best handholds were at the nodes: end, 1/4, 1/2). Personally, I think that there are a lot of hidden shock-minimizers in well-designed dhas and other long-handled blades. Otherwise, they wouldn't be worth swinging.

There's no reason that a moving weight on a blade couldn't serve a similar shock-absorbing function, but that's another design question entirely.

Personally, I'm surprised that the atlatl people weren't talking about tuning their dart and thrower systems to make the things accurate. After all, if the dart flexes the wrong way, it's not going to hit whatever the person was aiming at.

Fearn

Jim McDougall · 3rd July 2005, 03:31 PM

Outstanding discussion everybody!!!! It is extremely fascinating to read the well explained and supported observations here concerning the feasability of these weapons features. While edged weapons were in themselves primarily simple in thier dynamics, it is amazing how very complex their actual use and construction became. While the sliding weight feature discussed here remains purely conjecture found in literature thus far, many other interesting features are well established in developed examples, such as the thumb rings brought up on a concurrent thread and both hilt and blade shapes and construction.

It would appear that the sliding weight feature remains a figment of literary imagination as no existing examples have been seen, and such features are not mentioned in contemporary narratives or material describing edged weapons.

The mercury filled channel blades, while early examples seem to remain somewhat in question, the concept seems to have been applied in some latter examples of weapons, with this likely to be in response to the earlier tales of such weapons. An illustration of this occurs in at least one 'Bowie' knife produced in the 1860's with a hollow channelled blade containing mercury. Whether it was ever used is not described, however by its appearance (published in "The Bowie Knife", Norm Flayderman) it seems an extremely clumsy weapon.

As this excellent discussion continues, I remain hopeful that in some hidden corner of some archives or museum we will find evidence of the sliding weight on some long forgotten sword. I'm confident that if such a sword can be found it will be by the members and readers here!!

Meanwhile, the comprehension of physics and dynamics has always eluded me, but you guys make it understandable!!! Thank you so much!!

All the best,
Jim

Jens Nordlunde · 3rd July 2005, 04:37 PM

Hi Fearn,

I don’t think you are off subject, or if you are, it is only a fraction, as the whole subject is about dynamic power/shock-minimizing and stuff like that, so the way I see it, you are on track. I find, what you write about your dha-style sword most interesting. I have always been wondering about the long hilt, but I was wondering about it – you did something about it and tried it out, so now you have a knowledge, which I fail to have. Thank you for sharing.
In the start I did not think about the shock-absorption made by the weights, but I guess you are right, this could be an extra plus to such a construction. The hand would not have to take the whole of the blow – it would be divided – but with how much to the weight and how much to the hand?
I am sure, that those using an atlatl centuries ago, had everything tuned in, so that they were sure to hit the target – they could not afford otherwise.

Hi Jim,

You are right; the discussion gets more and more interesting, as we get more and more implements into the discussion. What I think we can agree on is, that sword smiths in the old times must have had a very good idea about dynamics and shock-absorption – more than we normally think of, when we buy a sword for our collection.

Jens

Jeff D · 3rd July 2005, 05:16 PM

Hi All,

While it isn't a sliding weight, the sliding hilt does change the point of balance. This is from the Landesmuseum.

Jeff

Jens Nordlunde · 3rd July 2005, 07:00 PM

Jeff, don't hold us waiting too long - which Landesmuseum?
There are several in the German speaking countries - so where is it?
BTW thanks very much for being the first to show a sword with a gliding weight

Jens

Jeff D · 3rd July 2005, 07:13 PM

Quote:

Originally Posted by Jens Nordlunde

Jeff, don't hold us waiting too long - which Landesmuseum?
There are several in the German speaking countries - so where is it?
BTW thanks very much for being the first to show a sword with a gliding weight

Jens

Oops Sorry Jens, this is the one in Zurich!

Jeff

fearn · 3rd July 2005, 07:47 PM

Hi Jeff,

Neat sword! I think it's a solution to a different problem, though. There's a book out there (forgot the title) that's a translation of a late-medieval German swordmanship manual.

In that manual, they show the proper way to use a long sword (i.e. hand-and-a-half sword) against a foe in plate armor. Basically, you have to have gloves, on, because you grab the sword half-way up the blade and use the tip as a bayonet/pry-bar to attack the cracks in the armor at extreme close range. I say bayonet rather than short spear, because the the stance reminds me of the way one holds a rifle with for bayonet practice, as do the moves (short stabs and swings, using the pommel and guard in place of the rifle butt).

My suspicion is that this sword was designed with this half-sword grip in mind: Normally, one's finger holds the guard at the base, but at close quarters, you grab the pommel with the other hand, push the guard forward with the lead hand, and use it in a half-sword grip, without sacrificing the guard on the forward hand.

As far as swords with sliding weights, doesn't Stone's Glossary have a picture? I don't have my copy with me, but I have a memory that it does.

Fearn

Tim Simmons · 6th July 2005, 08:04 PM

The sliding hilt is quite a good idea, how it worked in actual combat is another matter, but in theory it transforms a long thrusting weapon into something more general for close contact in the melee. Tim

Jens Nordlunde · 6th July 2005, 09:42 PM

Excelent Ian, but I think I on Google saw a training baseball bat with a sliding weight – only for training it said. It had some kind of sliding weight inside, but I am not sure what kind.

Imagine you had an arrow with a sliding weight on the haft. Before you took a shot, you pulled the weight back and when the arrow hit the target, the weight would make sure the impact was bigger than normal – would that work?

I hope to see the sword with the sliding hilt to morrow.

Jens Nordlunde · 7th July 2005, 03:20 PM

To day I went to Landesmuseum in Zurich, and found only very few weapons, and not the one Jeff show. When I asked where they were, I was told that they had packed them down, and no one knew when they would be on exhibition again, but to morrow a special exhibition would open with some weapons. I then went to the museums shop to ask after a book/catalogue showing weapons from the museums collection - no book, they had once had one, but it was sold out, and they did not plan another one

.
Jens

Ian · 7th July 2005, 05:02 PM

Quote:

Originally Posted by Jens Nordlunde

Imagine you had an arrow with a sliding weight on the haft. Before you took a shot, you pulled the weight back and when the arrow hit the target, the weight would make sure the impact was bigger than normal – would that work?

Jens:

I don't think this would have any effect, but perhaps it might if the weight shifted from the fletch to the head at the time of impact. Because we are talking about a piercing shaft, all energy would be concentrated at the point of impact, and the mass of the arrow lines up directly behind that point -- so however mass is distributed behind the point of contact would be immaterial, unless possibly if part of that mass is moving along the shaft at the moment of impact. Even then, I think the effect would be small and would need to be weighed against the effects of a rear-weighted arrow on its flight and accuracy. The small potential gain in penetrating power could well be offset by impaired accuracy.

Ian.

Rivkin · 9th July 2005, 06:21 PM

Hi Ian,

I don't think rod vs. string makes too much of a difference.

1. Equations are basically the same - they are basically the same for all oscillations. What is important is that we have oscillations around the equilibrium. Exapnding potential in Taylor's series, and taking derivative with respect to the displacement (which is going to give us force), we'll se that constant force is not there due to the equilibrium requirement (there are no forces in equilibrium, the derivative of energy is zero), force linearly proportional to the displacement is what gives us oscillations, force proportional to the displacement squared exist only in anisotropic bodies (asymmetric problem), cube will give us a nonlinear oscillator, and that is something we don't whant to deal with.

So it's always restoring force linearly proportional to the displacement.

2. Now the shape determinces boundary conditions - but if something is very long in one dimension, since if it would be infinite, it would have plane waves as a solution, if it's just long it has something similar to plane waves - sin or cos (basically sum of 2 plane waves propagating in the opposite directions).

Now for other dimensions - if it's a rod, it's most likely going to have a Bessel function or something like this (since it's like a drum). I think the problem is somewhere in the books on diff. equations.

I think plank is more suitable than rod in case of swords, but again - we are interested in transverse oscillations along the longest dimension.

Concerning additional b.c. - I meant that the tang is coupled to a human hand, so it's either unmovable, but under stress, or it's coupled to an oscillator.

I still don't agree to the rest of the things...

Sincerely yours,

Kirill Rivkin

Ian · 9th July 2005, 07:04 PM

Kirrill:

I have taken this way beyond my knowledge or comfort zone and cannot address your latest comments.

Much of what I have presented comes from the book that I referenced above by Robert Kemp Adair. He is presently Sterling Professor Emeritus of Physics at Yale University. You can find his contact information at http://www.yale.edu and using the search function for people on the home page.

Much of what you disagree with is cited in his book, including the comment that the resonant frequency of a baseball bat is related to its length and the thickness of the handle. He also points at that the centers of gravity, percussion and inertia are not the same and occur at different points along the length of a baseball bat.

BTW, Adair's book is available on the web for $1.00 plus shipping through this site http://www.abebooks.com

Ian.

Jens Nordlunde · 17th October 2005, 02:08 PM

In ‘The Indian Antiquary’, August 1873, page 217, W.F.Sinclair writes:

A common weapon among Hindustanis and Musalmans is a long steel rod with three or four small rings sliding on it. These, slipping forward as the weapon descends, add force to the blow, which is far more severe than might be supposed from the slender appearance of the weapon. It is also a good guard against sword-cuts.

3rd July 2005, 05:16 PM	#4
Jeff D Member Join Date: Dec 2004 Location: B.C. Canada Posts: 473	Hi All, While it isn't a sliding weight, the sliding hilt does change the point of balance. This is from the Landesmuseum. Jeff Attached Images

6th July 2005, 09:42 PM	#9
Jens Nordlunde Member Join Date: Dec 2004 Location: Europe Posts: 2,718	Excelent Ian, but I think I on Google saw a training baseball bat with a sliding weight – only for training it said. It had some kind of sliding weight inside, but I am not sure what kind. Imagine you had an arrow with a sliding weight on the haft. Before you took a shot, you pulled the weight back and when the arrow hit the target, the weight would make sure the impact was bigger than normal – would that work? I hope to see the sword with the sliding hilt to morrow. Last edited by Jens Nordlunde; 6th July 2005 at 09:55 PM.

7th July 2005, 03:20 PM	#10
Jens Nordlunde Member Join Date: Dec 2004 Location: Europe Posts: 2,718	Another museum has packed their weapons down To day I went to Landesmuseum in Zurich, and found only very few weapons, and not the one Jeff show. When I asked where they were, I was told that they had packed them down, and no one knew when they would be on exhibition again, but to morrow a special exhibition would open with some weapons. I then went to the museums shop to ask after a book/catalogue showing weapons from the museums collection - no book, they had once had one, but it was sold out, and they did not plan another one. Jens

3rd July 2005, 03:03 PM	#1
fearn Member Join Date: Dec 2004 Posts: 1,247	Hi Jens, This is getting a bit off subject, but I was partially thinking of atlatls when I was talking about weights absorbing shock in a sword. The other source of inspiration was a dha-style sword I made out of a machete. I very quickly learned that there were only two good handholds on the long handle: at the end, and about 1/4 of the length from pommel to tip. This was because the sword flexed on impact, and holding it at other points was a recipe for getting a very sore hand (the best handholds were at the nodes: end, 1/4, 1/2). Personally, I think that there are a lot of hidden shock-minimizers in well-designed dhas and other long-handled blades. Otherwise, they wouldn't be worth swinging. There's no reason that a moving weight on a blade couldn't serve a similar shock-absorbing function, but that's another design question entirely. Personally, I'm surprised that the atlatl people weren't talking about tuning their dart and thrower systems to make the things accurate. After all, if the dart flexes the wrong way, it's not going to hit whatever the person was aiming at. Fearn

3rd July 2005, 03:31 PM	#2
Jim McDougall Arms Historian Join Date: Dec 2004 Location: Route 66 Posts: 10,192	Outstanding discussion everybody!!!! It is extremely fascinating to read the well explained and supported observations here concerning the feasability of these weapons features. While edged weapons were in themselves primarily simple in thier dynamics, it is amazing how very complex their actual use and construction became. While the sliding weight feature discussed here remains purely conjecture found in literature thus far, many other interesting features are well established in developed examples, such as the thumb rings brought up on a concurrent thread and both hilt and blade shapes and construction. It would appear that the sliding weight feature remains a figment of literary imagination as no existing examples have been seen, and such features are not mentioned in contemporary narratives or material describing edged weapons. The mercury filled channel blades, while early examples seem to remain somewhat in question, the concept seems to have been applied in some latter examples of weapons, with this likely to be in response to the earlier tales of such weapons. An illustration of this occurs in at least one 'Bowie' knife produced in the 1860's with a hollow channelled blade containing mercury. Whether it was ever used is not described, however by its appearance (published in "The Bowie Knife", Norm Flayderman) it seems an extremely clumsy weapon. As this excellent discussion continues, I remain hopeful that in some hidden corner of some archives or museum we will find evidence of the sliding weight on some long forgotten sword. I'm confident that if such a sword can be found it will be by the members and readers here!! Meanwhile, the comprehension of physics and dynamics has always eluded me, but you guys make it understandable!!! Thank you so much!! All the best, Jim

3rd July 2005, 04:37 PM	#3
Jens Nordlunde Member Join Date: Dec 2004 Location: Europe Posts: 2,718	Hi Fearn, I don’t think you are off subject, or if you are, it is only a fraction, as the whole subject is about dynamic power/shock-minimizing and stuff like that, so the way I see it, you are on track. I find, what you write about your dha-style sword most interesting. I have always been wondering about the long hilt, but I was wondering about it – you did something about it and tried it out, so now you have a knowledge, which I fail to have. Thank you for sharing. In the start I did not think about the shock-absorption made by the weights, but I guess you are right, this could be an extra plus to such a construction. The hand would not have to take the whole of the blow – it would be divided – but with how much to the weight and how much to the hand? I am sure, that those using an atlatl centuries ago, had everything tuned in, so that they were sure to hit the target – they could not afford otherwise. Hi Jim, You are right; the discussion gets more and more interesting, as we get more and more implements into the discussion. What I think we can agree on is, that sword smiths in the old times must have had a very good idea about dynamics and shock-absorption – more than we normally think of, when we buy a sword for our collection. Jens

3rd July 2005, 07:00 PM	#5
Jens Nordlunde Member Join Date: Dec 2004 Location: Europe Posts: 2,718	Jeff, don't hold us waiting too long - which Landesmuseum? There are several in the German speaking countries - so where is it? BTW thanks very much for being the first to show a sword with a gliding weight Jens

3rd July 2005, 07:47 PM	#7
fearn Member Join Date: Dec 2004 Posts: 1,247	Hi Jeff, Neat sword! I think it's a solution to a different problem, though. There's a book out there (forgot the title) that's a translation of a late-medieval German swordmanship manual. In that manual, they show the proper way to use a long sword (i.e. hand-and-a-half sword) against a foe in plate armor. Basically, you have to have gloves, on, because you grab the sword half-way up the blade and use the tip as a bayonet/pry-bar to attack the cracks in the armor at extreme close range. I say bayonet rather than short spear, because the the stance reminds me of the way one holds a rifle with for bayonet practice, as do the moves (short stabs and swings, using the pommel and guard in place of the rifle butt). My suspicion is that this sword was designed with this half-sword grip in mind: Normally, one's finger holds the guard at the base, but at close quarters, you grab the pommel with the other hand, push the guard forward with the lead hand, and use it in a half-sword grip, without sacrificing the guard on the forward hand. As far as swords with sliding weights, doesn't Stone's Glossary have a picture? I don't have my copy with me, but I have a memory that it does. Fearn

6th July 2005, 08:04 PM	#8
Tim Simmons Member Join Date: Dec 2004 Location: What is still UK Posts: 5,843	The sliding hilt is quite a good idea, how it worked in actual combat is another matter, but in theory it transforms a long thrusting weapon into something more general for close contact in the melee. Tim

9th July 2005, 06:21 PM	#12
Rivkin Member Join Date: Dec 2004 Posts: 655	Hi Ian, I don't think rod vs. string makes too much of a difference. 1. Equations are basically the same - they are basically the same for all oscillations. What is important is that we have oscillations around the equilibrium. Exapnding potential in Taylor's series, and taking derivative with respect to the displacement (which is going to give us force), we'll se that constant force is not there due to the equilibrium requirement (there are no forces in equilibrium, the derivative of energy is zero), force linearly proportional to the displacement is what gives us oscillations, force proportional to the displacement squared exist only in anisotropic bodies (asymmetric problem), cube will give us a nonlinear oscillator, and that is something we don't whant to deal with. So it's always restoring force linearly proportional to the displacement. 2. Now the shape determinces boundary conditions - but if something is very long in one dimension, since if it would be infinite, it would have plane waves as a solution, if it's just long it has something similar to plane waves - sin or cos (basically sum of 2 plane waves propagating in the opposite directions). Now for other dimensions - if it's a rod, it's most likely going to have a Bessel function or something like this (since it's like a drum). I think the problem is somewhere in the books on diff. equations. I think plank is more suitable than rod in case of swords, but again - we are interested in transverse oscillations along the longest dimension. Concerning additional b.c. - I meant that the tang is coupled to a human hand, so it's either unmovable, but under stress, or it's coupled to an oscillator. I still don't agree to the rest of the things... Sincerely yours, Kirill Rivkin

9th July 2005, 07:04 PM	#13
Ian Vikingsword Staff Join Date: Dec 2004 Location: The Aussie Bush Posts: 4,361	Kirrill: I have taken this way beyond my knowledge or comfort zone and cannot address your latest comments. Much of what I have presented comes from the book that I referenced above by Robert Kemp Adair. He is presently Sterling Professor Emeritus of Physics at Yale University. You can find his contact information at http://www.yale.edu and using the search function for people on the home page. Much of what you disagree with is cited in his book, including the comment that the resonant frequency of a baseball bat is related to its length and the thickness of the handle. He also points at that the centers of gravity, percussion and inertia are not the same and occur at different points along the length of a baseball bat. BTW, Adair's book is available on the web for $1.00 plus shipping through this site http://www.abebooks.com Ian.

17th October 2005, 02:08 PM	#14
Jens Nordlunde Member Join Date: Dec 2004 Location: Europe Posts: 2,718	In ‘The Indian Antiquary’, August 1873, page 217, W.F.Sinclair writes: A common weapon among Hindustanis and Musalmans is a long steel rod with three or four small rings sliding on it. These, slipping forward as the weapon descends, add force to the blow, which is far more severe than might be supposed from the slender appearance of the weapon. It is also a good guard against sword-cuts.