True Combat Value of Wootz

Chris Evans · 28th October 2006, 10:27 AM

Folks,

When attempting to assess extraordinary cutting feats with swords, disregarding the attributes of the steel for a moment, we also have to consider the energy input required to make the cut.

To put it into simple terms: When felling green timber, the quality of the steel from which the axe is made is not all that critical, yet nobody would expect to cut through a smallish tree in a single stroke. Why not? Because the energy required exceeds that which even the most powerful swing can generate - And even if such a mighty lumberman did exists, the handle of the axe would fail.

Now, we have to remember that energy is required not only for the shearing of whatever is being cut, but also to displace the already cut material sideways, so that the thicker shouder of the blade can penetrates, not just its edge. Just what a considerable drain on energy this can be, is best illustrated when cutting with a sword into a large block of moist potters clay. The hardness/toughness/sharpness of the blade in this instance is comparatively insignificant, yet the blade will come to a halt after only a few inches of penetration. The energy of the sword is dissipated by the effort required to displace the cut clay and the friction that the flat of the blade encounters.

I imagine that cleaving through a human body clad in armour, even light armour, will require more energy than what can be delivered by even the mightiest sword arm - Never mind the hilt standing up to the task.

There is a often quoted story from the Napoleonic wars in which a Brit cavalryman cleaved a Frenchmans head, cutting right through his helmet, which I believe was made from brass. But despite that he was using the famous 1796 pattern sabre, and steel quality was not an issue, the cut only reached the victim's jaws, or thereabouts.

I think that extraordinary sword feats from the distant past parallel those of the old archers. Feats that when subjected to mechanical analysis, do not stack up all that well.

Cheers
Chris

tsubame1 · 28th October 2006, 11:07 AM

Quote:

Originally Posted by Chris Evans

Now, we have to remember that energy is required not only for the shearing of whatever is being cut, but also to displace the already cut material sideways, so that the thicker shouder of the blade can penetrates, not just its edge. ...OMISSIS... The energy of the sword is dissipated by the effort required to displace the cut clay and the friction that the flat of the blade encounters.

So true that the japaneses polishes their blade from back to edge and by hand instead of from handle to point with wheel-grinders as most of other cultures. In this way they create the Niku (http://home.earthlink.net/~steinrl/niku.htm)
that helps to displace the already cut material sideway. The way to perform the cut is also important, as well as the weight of the blade, a detail undervalued by many wannabe experts.

Chris Evans · 28th October 2006, 11:34 AM

Hi Carlo,

Quote:

Originally Posted by tsubame1

So true that the japaneses polishes their blade from back to edge and by hand instead of from handle to point with wheel-grinders as most of other cultures. In this way they create the Niku (http://home.earthlink.net/~steinrl/niku.htm)
that helps to displace the already cut material sideway. The way to perform the cut is also important, as well as the weight of the blade, a detail undervalued by many wannabe experts.

Absolutely so.

I don't know if you came across this article:

http://perso.wanadoo.fr/artsguerrier...abrekatana.htm

Unfortunately it is in French, but can be translated with Alta Vista's Babelfish. Makes for very interesting reading. I suspect that the sabre in question must have been an experimental one, because all the 19th century military sabres that I have seen, had edge geometries very similar to that of Japanese swords.

Deep fullers can reduce the friction encountered, but that to me is something of an overstated argument because on sabres, the COP usually falls right where the fuller ends.

Here are some measurements that I have made on two of my sabres:

Ames 1862 :Edge angle at COP: 22deg At 3"from pt 17.68deg Blade thickness at COP 5.5mm and 3"from pt 3.5mm

Brit 1854 :Edge angle at COP: 23.53deg At 3"from pt:20.6deg. Blade thickness at COP 5mm and at 3"from pt 4mm

Perhaps you could tell us how these geometries compare with that of Japanese blades. Unfortunately, I do not have one at the moment.

Cheers
Chris

Chris Evans · 28th October 2006, 11:42 AM

Hi Carlo and Folks,

Sorry about that link, but it seems to have gone dead.

It was the story of a French soldier, a keen sabreur and advocate of the cut, who whilst in Japan in the late 19th century compared his sabre against the native sword. In test cutting, he claimed to outdo the Japanese on account of his swords better edge geometry - No, he did not cut into helmets.

Whilst no doubt a thin foible on a sword adds up to deeper penetration, the sweet spot around the COP is reduced and the blade can be ruined much more easily with a less than expert cut.

That article is probably obtainable from another website, so I'll start looking.

Cheers
Chris

tsubame1 · 28th October 2006, 01:37 PM

Quote:

Originally Posted by Chris Evans

Hi Carlo,

Absolutely so.

I don't know if you came across this article:

http://perso.wanadoo.fr/artsguerrier...abrekatana.htm

Unfortunately it is in French, but can be translated with Alta Vista's Babelfish. Makes for very interesting reading. I suspect that the sabre in question must have been an experimental one, because all the 19th century military sabres that I have seen, had edge geometries very similar to that of Japanese swords.

Deep fullers can reduce the friction encountered, but that to me is something of an overstated argument because on sabres, the COP usually falls right where the fuller ends.

Here are some measurements that I have made on two of my sabres:

Ames 1862 :Edge angle at COP: 22deg At 3"from pt 17.68deg Blade thickness at COP 5.5mm and 3"from pt 3.5mm

Brit 1854 :Edge angle at COP: 23.53deg At 3"from pt:20.6deg. Blade thickness at COP 5mm and at 3"from pt 4mm

Perhaps you could tell us how these geometries compare with that of Japanese blades. Unfortunately, I do not have one at the moment.

Cheers
Chris

It's hard to me to give edge angles due to the above mentioned Niku that offers a curved surface to measure. Kasane (spine thickness) on many of either my long blades and/or which I've access to and/or in my files is in that range at COP, a bit less tapering toward the point. Mihaba (width) is crucial and very variable too. Anyway I'm not sure the different processes of making (mass versus custom) can give us a good comparison between the two.
Military swords, being subjected to standardization, are by far easier to
compare (type versus type) then blades made to tightly fit the needs of a specific man, not to talk about difference in tall between europeans and japaneses and avoiding the nightmare of the different smithing schools.
Japanese long blades had only a top-lenght standardization in Edo, every weight or thickness or width allowed as far as it was functional, so it can vary a lot and the homogeneity is only apparent, IMHO. Same for curvature. Another difference is that fullers (Hi) in japanese weapons most of the times passes the COP and its positive/negative phisical action versus the gain in weight is highly debated by Tameshigiri (cutting) practicioners.

ariel · 28th October 2006, 03:52 PM

The "viscosity" of the material is one thing. But my question is somewhat different: what about cutting hard steel? Of course, there is the issue of lateral displacement and mechanical engineers among us can easily calculate the proportion of energy going laterally in a wedge.
But there is also an issue of hardness and resiliency: can one reasonably expect a superb wootz sword to cut through a substantial steel gun chain several times without being broken? Even a minute angle of contact would redistribute the energy to shatter the blade. Similarly, while we see old steel mails with cuts ( and we do not know whether these were done by an axe), can we expect a wootz blade slice through multiple, hardened rings to effect a " total body" cut?
My suspicion is that there is much more than the quality of steel in the final effect. Also, wootz might have been much keener than regular steel, but it was of no advantage when dealing with real life objects.

Jeff Pringle · 28th October 2006, 04:21 PM

Quote:

Also, wootz might have been much keener than regular steel, but it was of no advantage when dealing with real life objects.

Yes, it would just mean you would not have to sharpen it as often - that may have been the most obvious practical effect of wootz' superiority as a steel in it's era.
I've only seen analyses of early medaeval european mail, but those show iron, not steel for the link material.

Gt Obach · 28th October 2006, 05:11 PM

also...... chain was usually made of wrought iron.. ... and this is a soft metal.... i really doubt that steel was used for this at this time.. ( big difference )

with a decent blade... you can cut into mild iron without much problem... i've done it several times... actually..... in the forge i have a cold cut that i use weekly to cut 1/2 mild rounds..... and rarely have to dress the edge...

i realize that not everyone deals with this daily basis... but a properly heat treated piece of steel with good edge geometry should have no problem with mild iron or wrought iron..

on cutting....... theres also a big difference between a chopping cut and a draw cut...... with a draw cut......distal taper has a big effect when pulling the blade through the target... .... aswell as adding to a swords ability to resist bending in a local area

Greg

28th October 2006, 10:27 AM	#1
Chris Evans Member Join Date: Mar 2005 Location: Australia Posts: 685	Folks, When attempting to assess extraordinary cutting feats with swords, disregarding the attributes of the steel for a moment, we also have to consider the energy input required to make the cut. To put it into simple terms: When felling green timber, the quality of the steel from which the axe is made is not all that critical, yet nobody would expect to cut through a smallish tree in a single stroke. Why not? Because the energy required exceeds that which even the most powerful swing can generate - And even if such a mighty lumberman did exists, the handle of the axe would fail. Now, we have to remember that energy is required not only for the shearing of whatever is being cut, but also to displace the already cut material sideways, so that the thicker shouder of the blade can penetrates, not just its edge. Just what a considerable drain on energy this can be, is best illustrated when cutting with a sword into a large block of moist potters clay. The hardness/toughness/sharpness of the blade in this instance is comparatively insignificant, yet the blade will come to a halt after only a few inches of penetration. The energy of the sword is dissipated by the effort required to displace the cut clay and the friction that the flat of the blade encounters. I imagine that cleaving through a human body clad in armour, even light armour, will require more energy than what can be delivered by even the mightiest sword arm - Never mind the hilt standing up to the task. There is a often quoted story from the Napoleonic wars in which a Brit cavalryman cleaved a Frenchmans head, cutting right through his helmet, which I believe was made from brass. But despite that he was using the famous 1796 pattern sabre, and steel quality was not an issue, the cut only reached the victim's jaws, or thereabouts. I think that extraordinary sword feats from the distant past parallel those of the old archers. Feats that when subjected to mechanical analysis, do not stack up all that well. Cheers Chris

28th October 2006, 11:42 AM	#4
Chris Evans Member Join Date: Mar 2005 Location: Australia Posts: 685	Hi Carlo and Folks, Sorry about that link, but it seems to have gone dead. It was the story of a French soldier, a keen sabreur and advocate of the cut, who whilst in Japan in the late 19th century compared his sabre against the native sword. In test cutting, he claimed to outdo the Japanese on account of his swords better edge geometry - No, he did not cut into helmets. Whilst no doubt a thin foible on a sword adds up to deeper penetration, the sweet spot around the COP is reduced and the blade can be ruined much more easily with a less than expert cut. That article is probably obtainable from another website, so I'll start looking. Cheers Chris

28th October 2006, 03:52 PM	#6
ariel Member Join Date: Dec 2004 Location: Ann Arbor, MI Posts: 5,503	The "viscosity" of the material is one thing. But my question is somewhat different: what about cutting hard steel? Of course, there is the issue of lateral displacement and mechanical engineers among us can easily calculate the proportion of energy going laterally in a wedge. But there is also an issue of hardness and resiliency: can one reasonably expect a superb wootz sword to cut through a substantial steel gun chain several times without being broken? Even a minute angle of contact would redistribute the energy to shatter the blade. Similarly, while we see old steel mails with cuts ( and we do not know whether these were done by an axe), can we expect a wootz blade slice through multiple, hardened rings to effect a " total body" cut? My suspicion is that there is much more than the quality of steel in the final effect. Also, wootz might have been much keener than regular steel, but it was of no advantage when dealing with real life objects.

28th October 2006, 05:11 PM	#8
Gt Obach Member Join Date: Mar 2005 Posts: 116	also...... chain was usually made of wrought iron.. ... and this is a soft metal.... i really doubt that steel was used for this at this time.. ( big difference ) with a decent blade... you can cut into mild iron without much problem... i've done it several times... actually..... in the forge i have a cold cut that i use weekly to cut 1/2 mild rounds..... and rarely have to dress the edge... i realize that not everyone deals with this daily basis... but a properly heat treated piece of steel with good edge geometry should have no problem with mild iron or wrought iron.. on cutting....... theres also a big difference between a chopping cut and a draw cut...... with a draw cut......distal taper has a big effect when pulling the blade through the target... .... aswell as adding to a swords ability to resist bending in a local area Greg