Curved vs. Straight
May 21, 2010 16:01:00 GMT
Post by Deleted on May 21, 2010 16:01:00 GMT
OK, time to do away with some common-on-sword forums nonsense again, just like with the "your leather scabbard contains tannins which cause rust" BS (when tannins are used to cause "black rust" or the oxide that prevents damaging rust).
As I've said before, I work and teach subjects like (bio)engineering and physics, but one of the things that astonishes me is how it can be used, inappropriately, to intimidate. Often with tons of equations, used to obfuscate the point, when truthful physics as often as not shows "eh, that doesn't really make a difference."
(Don't even get me started on how much worse it is on this and swords over at MyArmoury.)
The difference in question here: Do curved swords "cut better?"
Ignoring the semantic nuances of a word like "better," the answer is: No, not really.
That should be obvious to anyone who's done a significant amount of test cutting and/or followed forums like this one. Just look at any of the hundreds of videos. Shooter Mike, for example, with an Atrim 1557. (I bring it up because, damn, I want one. ;D) Cuts every bit as effectively as an curved sword.
In fact, let's crunch the numbers even in the abstract. Supposedly a curved sword facilitates a circular arm movement better for a more drawing cut. And it indeed is true that physics, via an inclined plane model, shows why a drawing cut can help in certain circumstances, by spreading the same work load out over a longer distance.
Just like walking up a slow ramp to an elevation of twenty feet is easier than jumping ten feet straight up; the longer overall walk spreads the effort out. And a draw cut of a knife on a tomato or a piece of lunchmeat utilizes the same principle, requiring less downward force.
Then again, a sharp cleaver can chop straight down into either pretty easily too. And a sword stroke is a strike, with only a slight draw, even under the best circumstances.
So, what IS the actual curvature of one of the most strongly curved swords, like say a 1796 LC sabre or a shamshir? Both of these models I have from Cold Steel I measured this morning at nine degrees of curve from the hilt to tip. Nine degrees.
The curve isn't continuous, so I measured each at the greatest point of curvature and got no more than 25 degrees. Plus this was near the tip, where there wouldn't be enough of the blade behind it to carry it through a target. The best you might say is a glancing tip-blow from a curved sword would be a bit more effective than if the sword were straight.
What's more, a common model for explaining curvature looks--and rightly so--at the area of the blade behind the impact. Taking a 45-degree angle as a base, the area of the one-inch wide Shamshir has almost as much blade area behind a blow as the 1 3/4 inch wide (at COP) Windlass Arbedo.
This does give an indication of a genuine advantage of curvature: it allows a slim, sexy blade of only, say, rapier width to be able to become an effective cutting sword. Then again, it makes thrusts a little trickier and not effective from a distance, so there an advantage disappears as a trade-off. Six of one, half dozen of another.
Don't forget either that I said the Shamshir has almost the Arbedo's width. Meaning the latter still cuts just fine, as does any straight sword of that width with decent blade geometry. In short, the relative cutting ability of straight vs. curved swords is a "distinction w/o a difference." Both do just fine, with scarcely a difference between them.
(Now there is a slightly more significant difference in "harmonics," with the arc of a blade dissipating force a bit better, meaning less hand shock w/o worries about distal taper in design etc. Then again, as many makers point out, there's the trickiness of shaping and heat-treating a curved blade and not messing it up. Again, a trade-off, and in any case hardly insurmountable differences--and a discussion for another time ...)
Bottom line, though, is don't get overly concerned with curvature or the lack thereof. It's an over-intellectualizing of the weapon akin to gun nuts agonizing over a few foot-pounds of KE and "should I buy the .308 or the .270?" Uh, either one will take your deer. It's also a kinesthetic laziness, trying to pick the "better" weapon, when the real matter is just pick any reasonable one and practice to become comfortable actually using it.
The truth is, pages of theorizing and equations be damned: sword use ain't brain surgery.
(At least not the kind where one usually worries if the patient survives...)
As I've said before, I work and teach subjects like (bio)engineering and physics, but one of the things that astonishes me is how it can be used, inappropriately, to intimidate. Often with tons of equations, used to obfuscate the point, when truthful physics as often as not shows "eh, that doesn't really make a difference."
(Don't even get me started on how much worse it is on this and swords over at MyArmoury.)
The difference in question here: Do curved swords "cut better?"
Ignoring the semantic nuances of a word like "better," the answer is: No, not really.
That should be obvious to anyone who's done a significant amount of test cutting and/or followed forums like this one. Just look at any of the hundreds of videos. Shooter Mike, for example, with an Atrim 1557. (I bring it up because, damn, I want one. ;D) Cuts every bit as effectively as an curved sword.
In fact, let's crunch the numbers even in the abstract. Supposedly a curved sword facilitates a circular arm movement better for a more drawing cut. And it indeed is true that physics, via an inclined plane model, shows why a drawing cut can help in certain circumstances, by spreading the same work load out over a longer distance.
Just like walking up a slow ramp to an elevation of twenty feet is easier than jumping ten feet straight up; the longer overall walk spreads the effort out. And a draw cut of a knife on a tomato or a piece of lunchmeat utilizes the same principle, requiring less downward force.
Then again, a sharp cleaver can chop straight down into either pretty easily too. And a sword stroke is a strike, with only a slight draw, even under the best circumstances.
So, what IS the actual curvature of one of the most strongly curved swords, like say a 1796 LC sabre or a shamshir? Both of these models I have from Cold Steel I measured this morning at nine degrees of curve from the hilt to tip. Nine degrees.
The curve isn't continuous, so I measured each at the greatest point of curvature and got no more than 25 degrees. Plus this was near the tip, where there wouldn't be enough of the blade behind it to carry it through a target. The best you might say is a glancing tip-blow from a curved sword would be a bit more effective than if the sword were straight.
What's more, a common model for explaining curvature looks--and rightly so--at the area of the blade behind the impact. Taking a 45-degree angle as a base, the area of the one-inch wide Shamshir has almost as much blade area behind a blow as the 1 3/4 inch wide (at COP) Windlass Arbedo.
This does give an indication of a genuine advantage of curvature: it allows a slim, sexy blade of only, say, rapier width to be able to become an effective cutting sword. Then again, it makes thrusts a little trickier and not effective from a distance, so there an advantage disappears as a trade-off. Six of one, half dozen of another.
Don't forget either that I said the Shamshir has almost the Arbedo's width. Meaning the latter still cuts just fine, as does any straight sword of that width with decent blade geometry. In short, the relative cutting ability of straight vs. curved swords is a "distinction w/o a difference." Both do just fine, with scarcely a difference between them.
(Now there is a slightly more significant difference in "harmonics," with the arc of a blade dissipating force a bit better, meaning less hand shock w/o worries about distal taper in design etc. Then again, as many makers point out, there's the trickiness of shaping and heat-treating a curved blade and not messing it up. Again, a trade-off, and in any case hardly insurmountable differences--and a discussion for another time ...)
Bottom line, though, is don't get overly concerned with curvature or the lack thereof. It's an over-intellectualizing of the weapon akin to gun nuts agonizing over a few foot-pounds of KE and "should I buy the .308 or the .270?" Uh, either one will take your deer. It's also a kinesthetic laziness, trying to pick the "better" weapon, when the real matter is just pick any reasonable one and practice to become comfortable actually using it.
The truth is, pages of theorizing and equations be damned: sword use ain't brain surgery.
(At least not the kind where one usually worries if the patient survives...)