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Vincent Le Chevalier




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PostPosted: Wed 08 Dec, 2010 1:11 pm    Post subject: Article about sword mass distribution         Reply with quote

Hello all!

Finally, after more years than I care to count playing with the concepts, I've managed to finish an article about sword balance and mass distribution...

It focuses on how to measure meaningful properties directly on the sword with as little calculus as possible (perhaps an addition or a subtraction somewhere Wink ). The properties have some intuitive interpretations in terms of handling for example, at least in my opinion... Of course I've left some things out and a more advanced interpretation is still a work in progress.

Read the article here!

Please don't hesitate to comment! It's the only way I'm going to be able to iron out the parts that are not clear...

I hope the method described can be used in reviews to introduce some more objectivity in the appreciations of handling and ease comparisons.

In appendices you will find raw data measured on swords and some mathematical demonstrations that could be of interest to the maths/physics geeks out there Wink

Regards,

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Vincent
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E Sideris




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PostPosted: Wed 08 Dec, 2010 1:21 pm    Post subject:         Reply with quote

That's fantastic, Vincent! You're doing some really important work, no matter intimidating the physics might initially seem to some.

It's really exciting to see all the work that's coming along in the study of swords, from scientific study such as this to the "re-constructional archaeology" of modern smiths to the methodological practice of swordplay interpreted from period texts!

Good work!

Although I have to say, the video is now working on my computer.
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Vincent Le Chevalier




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PostPosted: Wed 08 Dec, 2010 1:27 pm    Post subject:         Reply with quote

E Sideris wrote:
Although I have to say, the video is now working on my computer.

Ah that's the kind of problems I feared Worried
Can you tell me what media player you're using, and what kind of error you encounter? Perhaps I could try different encodings...

And thanks for the kind words Happy

Regards

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Vincent
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Maurizio D'Angelo




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PostPosted: Wed 08 Dec, 2010 1:45 pm    Post subject:         Reply with quote

Great.
Honor of Merit, Vincent. Maybe you're one of the leading experts in this.
I remember learning the basics from your teachings.
Thank you for your work.

P.S. the video stops, inexplicably.
media player 9 series
FMP4 codec used.
Now I see for download.

now, all ok. Happy

Ciao
Maurizio


Last edited by Maurizio D'Angelo on Wed 08 Dec, 2010 2:15 pm; edited 2 times in total
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Todd Salazar





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PostPosted: Wed 08 Dec, 2010 2:05 pm    Post subject:         Reply with quote

Thanks for the terrific article, Vincent. As a statistician, I appreciate your scientific approach and the mathematical formulas included in your appendices.

-Todd
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Vincent Le Chevalier




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PostPosted: Thu 09 Dec, 2010 12:28 pm    Post subject:         Reply with quote

Well I'll try to convert the video this week-end into another format that would hopefully be supported out-of-the-box on most systems... The video is quite short anyway and just there to show the kind of motion described in the article.

I'm glad you appreciate the approach, I hope that there are not too many errors left in the formulas Happy

Regards,

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Vincent
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Vincent Le Chevalier




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PostPosted: Sun 12 Dec, 2010 12:17 pm    Post subject:         Reply with quote

Hello!

I have just updated the page with a new format for the video, that will hopefully be supported almost everywhere...

Still at the same place!

Regards,

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Vincent
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Scott Hrouda




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PostPosted: Sun 12 Dec, 2010 12:31 pm    Post subject:         Reply with quote

Vincent,

I've had just enough time to breeze through your article and I must say that I'm impressed. The amount of time and thought required to assemble all the various pieces is mind boggling. As I am very fond of analytical analysis, this article is high on my list of things to read in depth and chew on over the upcoming holiday season. Happy

Cheers

...and that, my liege, is how we know the Earth to be banana shaped. - Sir Bedevere
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Peter Törlind





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PostPosted: Mon 13 Dec, 2010 5:39 am    Post subject: Interesting         Reply with quote

I really like the 'centers of oscillation’

I would also like to see the system with hilt point mass and a hilt dynamic distance (from the cross). It would clarify different hilt configurations and their importance of the sword balance, (e.g the difference between a light hilt and a heavy pommel or the opposite)

It is of-course easer to measure the dynamic length if you approximate the hilt system as a point mass in the hilt. Because you can to the wiggle test holding in the pommel...
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Vincent Le Chevalier




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PostPosted: Tue 14 Dec, 2010 2:37 pm    Post subject:         Reply with quote

Hi Scott!
Scott Hrouda wrote:
I've had just enough time to breeze through your article and I must say that I'm impressed. The amount of time and thought required to assemble all the various pieces is mind boggling. As I am very fond of analytical analysis, this article is high on my list of things to read in depth and chew on over the upcoming holiday season. Happy

Thanks for the compliments Happy I really hope the article will satisfy your tastes for analytical analysis Big Grin

Regards,

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Vincent
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Vincent Le Chevalier




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PostPosted: Tue 14 Dec, 2010 3:03 pm    Post subject: Re: Interesting         Reply with quote

Hi Peter!

I'm not completely sure I understand exactly what you mean but I'll try to answer as precisely as I can...

You can represent other two-mass equivalent objects indeed, with different points of origin, in particular the pommel. The thing is that they don't bring more information to the table; if you've got one of them, you have them all! From just one two-mass equivalent, you can deduce an infinity of others, because it gives all of the information about rigid body dynamics already.

So I could give other two-mass equivalent objects, but they won't tell you more about hilt construction than is already apparent in the original data. You cannot measure the mass of the pommel, nor the mass of any individual sword component, without disassembling the sword; actually different hilt constructions could give the exact same dynamic properties.

That being said, adding mass at the pommel has the effect of augmenting cross weight, lowering blade weight, and augmenting dynamic length (measured from the cross). You can somewhat guess which swords are balanced with a heavy pommel thanks to that... A sword that has a significant blade weight and a long dynamic length (relative to its dimensions) probably has a heavy pommel to make up for a blade that is not sufficiently tapered. That's a general idea; of course looking at other swords of the same type is necessary in order to judge more objectively.

Now, doing the waggle test from the pommel and not the cross would be possible. I have explained in the article why I chose the cross as a reference; I find the results correspond more closely to my own perception that way, and I think it makes practical sense as it is difficult to find a precise spot on every sword that is taken to be the location of the pommel. What to choose: junction handle-pommel? top of the pommel? bottom of the pommel? Center of the pommel?

However, doing a waggle test from a different gripping point has one usefulness: it allows to check and compensate for errors during the waggle test. Hopefully I'll detail that amelioration of the procedure in a future article...

Let me know if my answers were relevant at all Happy

Regards,

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Vincent
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Maurizio D'Angelo




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PostPosted: Tue 14 Dec, 2010 3:37 pm    Post subject:         Reply with quote

Vincent
a question if I understand the center of oscillation.
Can I find the center of oscillation at the exactly tip of the blade? if radius is ugual lenght the blade.
I refer to your formula.
If the answer is yes, then it will be very strong thrust in this sword. Is it so?
There is a relationship between this, if I understand it.

Pivot point and center of the oscillation, what is the difference in terminology and differences from such a dynamic point of view. If you can explain better.
Thanks in advance.

Ciao
Maurizio
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Vincent Le Chevalier




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PostPosted: Wed 15 Dec, 2010 12:33 pm    Post subject:         Reply with quote

Hi Maurizio!
Maurizio D'Angelo wrote:
a question if I understand the center of oscillation.
Can I find the center of oscillation at the exactly tip of the blade? if radius is ugual lenght the blade.
I refer to your formula.
If the answer is yes, then it will be very strong thrust in this sword. Is it so?
There is a relationship between this, if I understand it.

Indeed the center of oscillation can on some weapons be found at the tip or even beyond the tip; I have foils that behave that way. On older sword types it is rare in my (admittedly limited) experience.

With that big dynamic length, you get an increased feeling of stability: the swords "wants" to remain pointed in a direction, and is less sensitive to perturbations. That favours thrust-centric swordsmanship (that explains why it appears on foils). That being said, Peter Johnson observed that even rapiers do not generally have their center of oscillation at the tip; I now think this is because it makes the weapon unwieldy. Basically the big dynamic length make it slow in the swing, you have to force through the cut instead of letting the weapon swing by itself. Modern fencing sabres, for example, do not have their CoO at the tip like foils do.

Nowadays, I believe that the most natural position of the CoO of the cross is not at the tip but further down the blade, just around where it would be on a stick of similar length... The sample of swords I have measured seem to fit that rather well. I'll need to write another article about that Happy

Quote:
Pivot point and center of the oscillation, what is the difference in terminology and differences from such a dynamic point of view. If you can explain better.

This is just a difference in terminology. "Pivot point" is not really as accurate, center of percussion is loaded with more or less correct meanings in the sword context. Center of oscillation is an accurate term because this is what the waggle test determines, and has no associated preconceptions among sword fans Happy That's why I switched terminology...

Regards,

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Vincent
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Vincent Le Chevalier




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PostPosted: Thu 13 Jan, 2011 2:39 pm    Post subject:         Reply with quote

Hello all,

Just a notice that I have made some minor corrections to the article (nothing really significant) and added a word of caution in the intro, that I'll repeat here just in case:

Quote:
Measuring a weapon involves some handling. Be careful when you do it with sharp blades. In fact be careful in general! I do not want people to get hurt while just trying to measure swords. If you feel your grip is not secure enough, if there are any living beings nearby (including yourself obviously) that could be hurt by a sword falling down, just lay the sword down and rest. If the sword falls and is not worth any piece of your own skin then do not attempt to catch it. Do not take chances...

The risk is nowhere near that posed by actual martial moves but better be safe than sorry...

Still at the same place!

Regards,

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Vincent
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Johan Gemvik




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PostPosted: Thu 13 Jan, 2011 4:59 pm    Post subject:         Reply with quote

Very good! Many thanks for sharing.
"The Dwarf sees farther than the Giant when he has the giant's shoulder to mount on" -Coleridge
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Johan Gemvik




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PostPosted: Thu 13 Jan, 2011 5:02 pm    Post subject:         Reply with quote

Vincent, I've been considering using knife-safe gloves or maille eqivalent such as oyster gloves for demonstrations. Then one can safely catch falling sharp blades, at least with some practice.
"The Dwarf sees farther than the Giant when he has the giant's shoulder to mount on" -Coleridge
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Ozsváth Árpád-István




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PostPosted: Sat 15 Jan, 2011 3:51 am    Post subject:         Reply with quote

Thanks Vincent, I'd been waiting for long for this article. Very good indeed.
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Vincent Le Chevalier




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PostPosted: Sun 16 Jan, 2011 9:38 am    Post subject:         Reply with quote

Hi Johan!

Johan Gemvik wrote:
Vincent, I've been considering using knife-safe gloves or maille eqivalent such as oyster gloves for demonstrations. Then one can safely catch falling sharp blades, at least with some practice.

True, that would be a way around... Still, I prefer to err on the side of cautious Happy I've never felt the need to use anything more substantial than a leather glove to do the measurements even on sharp swords myself, and never had any problem... Never had a falling sword either though Wink

Regards,

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Vincent
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Vincent Le Chevalier




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PostPosted: Sun 16 Jan, 2011 9:43 am    Post subject:         Reply with quote

Hi Arpad!

Ozsváth Árpád-István wrote:
Thanks Vincent, I'd been waiting for long for this article. Very good indeed.

Indeed I've been slow getting there... I hope it can be useful to you! There isn't much in it on how the properties can be adjusted by sword makers but perhaps the data I give can serve you as a point of comparison...

Regards,

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Vincent
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Vincent Le Chevalier




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PostPosted: Sun 12 Jan, 2014 12:00 pm    Post subject:         Reply with quote

Hello!

I've migrated this article to a new home... The old one remains up but I don't know for how long Confused

Regards,

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Vincent
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