Understanding European Swords - From an Engineering and Physics Perspective

[Luke March]

You've heard it before. Or, perhaps, if you're one with more experience in the area, you've said it or something like it:

"Historical blades handle better than most replica blades."
or
"You should handle originals to understand what a real sword is like."
or
"To start making better swords you should handle well-made reproductions"

Now this has always made me wonder, "What is it that separates originals and well-made replicas from others?"

Of course, the answer has to do with the thickness and cross section; nearly everyone who wants has access to pictures of originals and well-made replicas, but that just gives us the silhouette. We usually have no information about the thickness, and (also usually) not being swordsmen, we just guess at what might work. The generally given solution is to practice swordsmanship and handle originals until you get an idea of what a sword is supposed to be like.



What I want to do is understand the engineering and physics principles for making a sword that "handles correctly."



Now, before anyone jumps on me, I want to offer these "disclaimers": I understand that swords traditionally were and are handmade, no two exactly alike, etc. There is of course a difference between understanding a system and having the skills to build it. I also understand that certain sword properties will depend somewhat on the preferences of the swordsman, and the type of sword. For the purposes consistency in this discussion, let us assume we are talking about the European Longsword.

I also understand that some would claim that the sword is "far too complex" for "that kind of analysis" (i.e., an engineering and physics analysis) because there are "far too many variables." Quite frankly, I think that idea is rubbish. Engineers and Physicists have characterized and understood and built systems far more complex than the sword.

Of course, to understand what is meant by "handles correctly," one would also need an understanding of historical swordsmanship, which is something I am working to acquire (studying WMA/RMA/HEMA, not sure what the difference between them all is, if any)

There are a number of characteristics which would have to do with the handling characteristics of a sword:
Weight
Balance (Center of Gravity or center of mass)
Dimensions (length of blade and hilt)
Blade Flex
Center of Percussion (has nothing to do with "harmonics")
Modes of Vibration



Weight - I have not heard an awful lot about weight, other than the things I have read to dispel the rumors of the 20 lb sword (I still ask people how heavy they think a sword would be, and they say 30 lb or 40 lb). That being said, I think the weight for a longsword is supposed to be in the ~4 lb range. (Someone please correct me if this is wrong, or add more information if you have it! Preferably with links to original sources.)

Balance - Again, something I know little about, other than what I have often read about the center of gravity being 3 to 5 inches above the cross, and (as a generalization and at risk of oversimplification) stabbing swords have the balance closer to the hilt, chopping swords further out.

Dimensions - Don't have much to say here, other than that this will affect the balance and center of percussion, and will depend on the swordsman. If you have sources on the proper dimensions for a longsword, especially in proportion to the swordsman, let me know!

Blade Flex - This would have more to do with material and heat treating, as well as thickness. I can imagine a non-destructive test method to measure this, using equipment I have access to.

Center of Percussion - Now here is something I think is often misunderstood. There is an excellent article about this at the ARMA: http://www.thearma.org/spotlight/GTA/motions_and_impacts.htm (Warning - the article is quite long, ~30 pages if it is printed all out). I will not re-write here what has already been written about so well. Also in relation to the CoP is this research on baseball bats, which I believe is quite relevant to swords, since the basic physics is the same: http://www.acs.psu.edu/drussell/bats.html

Modes of Vibration - This is something where I have actually done some research myself. As part of my acoustics class, we did a vibration analysis research project on an object of our choice. We did a sword.
Unfortunately, I have access to neither high-quality replicas (out of price range for a college student) or to originals! So I used the next best thing I had - which happened to be the united cutlery "sword of strider" replica from lord of the rings.
The results were still interesting. In addition to the actual experimental data we gathered from the tests, we did a computer simulation, called a Finite Element Analysis, to look at the vibration, and we did a completely theoretical approach, which started with math and physics principles to build up a prediction for the vibrational modes of the sword. (Euler-Bernoulli beam theory with mass loaded / free boundary conditions)

Attached is one of the modes of vibration discovered in our experiments; the pommel is to the left, and the peaks are greatly exaggerated for clarity. The sword is viewed edge-on. See also http://s169.photobucket.com/albums/u228/Luke_SkyMarcher/Vibration/?action=view&current=Mode241_69Hz.mp4

My tentative conclusion from some of the computer modeling we did, and also the comparisons between the theoretical and experimental outcomes, would be that blade geometry has little to do with mode shape. Probably much more important than where a particular node lies on the blade is the vibrations around the tang, which, according to Dr. Hrisoulas, is where most sword breakage occurs. There is also a section on this in the ARMA article I linked to earlier.



What I would like to do in the future is perform measurements on good reproductions, and hopefully originals at some point. I am planning to build an apparatus for easily measuring the center of percussion of a blade (see the ARMA article for how this is done), and I will have access to the vibration testing equipment during three month segments of time for the next year and a half.

My questions for you all are:
Do any of you have sources to help fill in some of the gaps?
Does anyone have originals or well-made replicas that they would like to have tested? This would obviously be more easily accomplished if you were in the Michigan area, or willing to come for a visit.

Any constructive input or discussion is welcome!

Luke

41.69 Hz.bmp

[Ratel10mm]

Have you come across Peter Johnsson yet? I had the pleasure of attending one of Basher's forge ins where Perer gave a lecture about swords.
Some of the attendees had brought reproduction swords, which needed quite a lot of force to maneuvre. Peter's sword, basically the same (he'd designed the repro sword) needed no such force. It seemed to be where you wanted it almost before you knew where you wanted it! You felt like you could wield it all day.
Peter's lecture was about what made this difference. The balance points, nodes, etc. I still wish I'd owned a video camera & had video it.

[Ric Furrer]

"I also understand that some would claim that the sword is "far too complex" for "that kind of analysis" (i.e., an engineering and physics analysis) because there are "far too many variables." Quite frankly, I think that idea is rubbish. Engineers and Physicists have characterized and understood and built systems far more complex than the sword."

Very true, but those far more complex systems have far more money paid to those who did the study. It appears you are trying to work out a system of your own...good for you.

My question...have you measured ten originals of any single time period or culture? Yes they are hand made, but I think you would be rather surprised with the results....more commonalities than differences. Museums are not likely to let you put anything to a blade but your hands..many do not like you taking measurements with plastic calipers.
I suggest you find a collector that is sympathetic.

As to flex...it is almost completely independent of heat treatment and related to cross-section only. Take two bars of store bought W1....heat treat one and then lock them both in a vise..they will bend the same under the same load...but the annealed one will take a set sooner.
As Kevin Cashen says "if you want it flexible then make it thin"

I second Peter Johnson...quite the learned guy when it comes to what you are researching....he should be on your list of experts to contact.

Ric

[basher]

the real difference between a period weapon and a modern reproduction is that the original was made to fit a then current and deadly purpose and tested in the arena of same.

reproductions have no real value if what you are interested in are origional period swords.

If you expect a reproduction to have the same dimensions , subtleties and maker inequalities as an original piece you will find yourself very disappointed, there are very very few modern makers who really take the extreme measure of recreating an origional to the point of their modern piece being anywhere near. At most what you get is a look-alikey and weigh-alikey.
there will be exceptions of course but they are few and far between and by the exacting nature of recreating an original they will be expensive.

I would narrow your sample down to a certain type of long sword at a certain place in a certain period, what you are asking is akin to trying to model the european car(over the last100 years) and limiting your sample to only rear wheel drive.

[ThomasPowers]

Your weight is quite far off, for nearly 1000 years of the European Middle Ages a good standard weight for a using sword was about 2.5 pounds. (for giggles that's a good standard weight for a katana too!)

One problems with replicas is that they are often machined and so have a lot more problems getting the tapers that are so easily produced with the hammer and anvil---in general a blade should taper in almost all directions!

Cross section makes a big difference in how a blade weighs and handles. Many replicas have a central flat where medieval blades will be fullered.

You really have to go to the originals; there is just no getting around it. Many museums will allow access to blades that are not on display if you approach them correctly. Having an explicit protocol in how to measure the blades will give you data that you can compare against other examples.

Good to see you taking in account vibration nodes! Having a node at the grip makes all the difference in a sword that stays in your hand like it's glued and one that wants to jump out every time you have a strong impact.

[Luke March]

Ratel -
Thank you for that. I've started looking up Peter Johnsson, and yes, he seems to really know his stuff! And his work looks really nice, too.

Ric -
You got it! I am basically trying to work out the system "on my own." Of course, I don't want to start completely from scratch where others have already figured things out, but I also know you can't just believe everything you read out there about swords and how they work. (You couldn't anyway; so much of it contradicts itself).

If I could get the chance to measure even one original, that would be awesome. The ideal thing would be to make measurements of many, many originals, and not just dimensions but also weight, balance point, CoP, etc, etc, etc. From the sound of things, most museums would not like having vibration testing done, although I am quite certain it would not harm the blade (at least ones that aren't all rusted): it involves attaching an accelerometer to one point with wax, and making little taps all over the blade with a tiny plastic headed hammer.

That is interesting about the flex. I guess I had just assumed that harder=stiffer. But your explanation makes sense.
By the way, I came across Kevin Cashen when I was researching Peter Johnsson - and found out he lives about 40 minutes from my house. His work looks amazing too - and I like his attention to detials of metallurgy.

Basher -
I guess my point in mentioning well-made replicas is that I have heard that some of them have the same or similar handling characteristics as the originals. In any case, I would want to compare them to originals to see similarites and differences.

"I would narrow your sample down to a certain type of long sword at a certain place in a certain period, what you are asking is akin to trying to model the european car(over the last100 years) and limiting your sample to only rear wheel drive."

To use your analogy, (and apply to american cars since I'm not as familiar with european cars), I think what I am asking is more in the line of understanding how the car works - If I looked at a Model T, a 1968 Cadillac, and a 1999 Pontiac, there wouldn't be much that was apparently similar.... But under the hood, they are all internal combustion engines. If I were 600 years in the future, and wanted to understand "how cars worked in the 20th century," I could get a good a good idea of the operating principles by looking at those three. If I wanted to build a specific make and model year, I would do best to study as many examples of it as possible. But for understanding the general principles, the more variety the better. (IMHO). Of course, this needs to have bounds - studying civil war sabers will not tell you much about the principles for longsword design- but I wonder if the bounds really need to be as narrow as you put them.

I think information is transferrable, too. Studying principles of longswords will not necessarily tell you the right principles for a single-handed sword, any more than studying principles of semi trucks will tell you how to build a sports car, but some information will be transferable.

Your point is well taken though - perhaps a better thing for me to do would be to group longswords according to era and location, also taking into account the fight traditions in those areas. (I'm by no means expert in swordsmanship, but I do know enough to know that the German and Italian schools had some differences; perhaps these differences were reflected in their sword design principles) Then the data could tell me whether or not putting them together in a larger group is justified.

Thomas-
Glad to have you correct me on the weight. I have read different numbers in different places, anywhere from "almost never over 2 lb" to "between 3 and 5 lb." I guess that's part of the point of this quest of mine: accurate information. There's just way too much bad information out there. That's part of the reason I did my vibration project on swords.

Do you have any advice for having museums allow you to take data on their artifacts?
Also, I realize most surviving european longswords... are in Europe. Have you found any good museums in the U.S. with originals?

[ThomasPowers]

First thing do you attend the International Congress of Medieval Studies in Kalamazoo MI? Coming up early May!
http://www.wmich.edu/medieval/congress/

excerpt from the schedule pdf:

Sword in Hand I: Practical Insights into the Medieval Long Sword
Sponsor: Oakeshott Institute
Organizer: Annamaria Kovacs, Independent Scholar
Presider: Annamaria Kovacs

Combat Training for the Longsword: The Efficacy of the Proliferation of Options
following a Single Entry into Any Mode of Combat in the Flos duellatorum
Bob Charron, St. Martin’s Academy of Medieval Arms
Recipes for Medieval Sword Blades
Craig Johnson, Oakeshott Institute
Specialized Armor for Tournaments: The Nuremberg Stechzeug
Josh Davis, Oakeshott Institute
There’s No “True Art of the Sword”
Russell Mitchell, Independent Scholar

Sword in Hand II: But One Art of the Sword: Comparison between Fiore’s and
Lichtenauer’s Approaches to the Fight (A Demonstration)
Sponsor: Oakeshott Institute
Organizer: Annamaria Kovacs, Independent Scholar
Presider: Annamaria Kovacs
A demonstration with Greg Mele, Freelance Academy Press/Chicago Swordplay
Guild, and Keith Alderson, Oakeshott Institute.


Also look into De Re Militari

De Re Militari is an international scholarly association established to foster and develop interest in the study of military affairs and warfare in the Middle Ages and the Early Modern Period. Our society publishes the Journal of Medieval Military History and organizes academic conferences focusing on medieval warfare.


If you want to really get into this sort of thing you need to meet and associate with the people doing likewise. Having such friends can get you invitations to examine various museum pieces too!

[Luke March]

Wow, that's really cool - I didn't realize that happened so close to me. I would like to go to that - if only for the two sword sessions.

I've got a brother who lives in Kzoo, and I could stay with him.... The only thing holding me back is the money, since it would involve me missing work, plus paying $85.... which is a lot for someone in engineering school. I guess I'll have to see how my finances are doing by April 25.

I take it this is an ideal event to "meet and associate with people doing likewise." Are you going to be there, Thomas?

I've started looking at De Re Militari - very interesting stuff!

[r smith]

You should go and do whatever it takes to get there.

[ThomasPowers]

I used to go when all I had to do was drive a bunch of hours from Columbus OH and rent a room in the dorm.

Now that I'm in NM I don't get out that way very often.

If you have a place you can stay I'd strongly suggest you go! Peanut butter and jelly makes a cheap feed---just eat one when it starts to sound good!

I haven't checked the prices lately---is there a student pricing option?

[Luke March]

Yep - Student pricing is $85, normal pricing is $140. The reason I'm hesitant is because $85 is still quite a lot for me.... even with food and housing taken care of. I would love to go, though.


Maybe I should add "help fund sword research" to my Etsy ad for my twisted J-hooks.... If I could sell the one's I've made, that would cover the cost :rolleyes: . Oh well. I have yet to make any money from any blacksmithing I've done.