Hail everyone!

I'm working on my first sword for some time, it's in the final stages, but now I'm facing some decisions that are hard to take, so I'm asking for your advice.

To give you an idea about how my sword will look like, the closest relative is the Albion Templar.

Here are some characteristics:

Blade length: 80 cm
Total length: 95-98 cm (not decided yet)
Blade width: 44 mm at base tapering to 30 mm
Blade thickness: 7 mm at guard tapering to 3.5 mm (5 cms from tip)
Blade mass: 770 g
Crossguard mass: cca. 100 g
Pommel mass: 240-330 g (not decided yet)
Pommel diameter: 45-50 mm (not decided yet)
CoG without guard and pommel: 24.5 cms from guard
CoG with guard, without pommel: 21.5 cms from guard

Now I have some dilemmas:

Short (105 mm) or long grip (125 mm)?
Light (240 g) or heavy (330 g) pommel?

Note that I'm 6' 0'' tall and I have a rather large hand, so normal 9-10 cm grips feel quite uncomfortable. A 10,5 cm grip feels fine with hammer grip, but no so great for handshake grip or when aiding with the left hand.

A light pommel looks better and and will lead to a lighter sword of cca. 1100 grams but with a farther CoG (cca 14 cms from guard) with some little variations depending on grip length. A large pommel besides unbalancing the sword will add weight but leads to a better CoG (11,5 - 12 cms from guard).

Following Vincent's instructions I wrote a little program to calculate some basic characteristics and determining pommel weight - CoG variations. I attached some screenshots with different setups.

[ Linked Image ]

http://www.postimage.org/image.php?v=Ts5bfxS

Note that the pivots are not yet measured so any characteristics related to them should be ignored.

I will appreciate any advice or opinion so please help!

Arpad

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1) First make grip and pommel of some modeling material (clay-like stuff). Check if it feels OK. If it does not make the grip shorter/longer as required and check again. Repeat as many times as needed. And if you plan to use the sword with a gauntlet on make the grip at least 1.5 cm longer than you would make for bare hand. Personally I prefer longer grips. After all, you can handle a long sword with 30 cm grip with one hand without any problem.
2) Make the grip, put the crossguard and the grip on the tang. Attach weigh to the end of the tang equal to the desired weight of the pommel. Check if the sword feels OK. Reduce or increase the weight if needed until you get what you want. This way you shall know the required weight of the pommel.

Finally, length of the grip and balance of the sword are purely personal preferences and depend on what you expect from your blade. Your sword will be a better cutter with a lighter pommel, but will be fester with the heavier one.

For this kind of sword lighter pommel and overall lighter weight but further out PoB might be more appropriate but one should decide what he likes the feeling of more...

Thanks Aleksei, your methods are simple yet very practical indeed.
I attached a cca. 200 g piece with tape and the sword felt lazy and blade-heavy. With 400 g pommel the sword was quick and responsive, but a bit bulky and offset. The correct weight is between these two values.
Now I have to figure out an adjustable pommel, adding weights and swinging the sword is quite challenging. I will try to secure a 200 g weight on the tang fitted with strong neodymium magnets (those found in hard drives - older models have bigger and stronger magnets) then by adding weights (sticking coins or something) I can fine tune the pommel until the sword feels just right.

I still don't understand why period swords had such short grips. I will stick to the long grip, I can shorten it any time after all. It feels much comfortable and offers a greater freedom for different techniques.

Luka, those swords might have a better mass distribution. Unfortunately I couldn't find a wider piece of material to make a better profile tapper.

I'm really curious about how can on hold in a handshake grip a viking sword with huge hammer-like pommel and notoriously short grip... or a roman gladius.

Unfortunately I have no access to authentic swords or good replicas to get an idea about how it feels in hand. I have only a few XIX. century military swords, but they are a different story.

the handling is favored the first solution has a better inertia. Why aren' t there other points of inertia? X Y Z? You can post the formula you calculated the pivot.

Ciao Maurizio!

I don't have a formula to estimate the first pivot points pair, only the "wiggling method". I wrote the software based on Vincent's formula to get the other pivot points knowing the first and vice-versa. Unfortunately I used my old studenthood method (understand-learn-take the test-drink-forget). It was something related to geometric representation of moment of inertia and constant area rectangles. Oh, yeah now I remember:
d(R1,G) * d(P1, G) = d(R2,G) * d(P2, G) where
R1 - first rotation point on hilt
P1 - pivot point on the blade for R1
R2 - second rotation point on hilt
P2 - pivot point on the blade for R2
G - balance point

Those pivot points in the pictures I postedare not correct, I have not yet done the wiggling test.

What you mean by the X,Y and Z. Moment of inertia for all 3D axis?

Hello!

The formula is correct Arpad, glad to see you remember it :)

I'd go with the second solution personally (that is, light pommel and short handle), but perhaps that's more because of my own tastes...

Maurizio,

I don't think it's important to consider the whole inertia matrix for swords. Assume X is the direction of the blade, Y is in the plane of the edges, Z points out from the flat, . The sword is an order of magnitude bigger in the X direction than in the Y direction, and another order of magnitude bigger in the Y direction than in the Z. That means that the moment of inertia around X can be neglected, and that the moment of inertia around Y and Z are roughly the same.

Regards,

Ciao Vincent,
If I understand the value of X may be important for thrust sword?
for a cutting sword is more important than Y and Z?
this is purely academic, perhaps, hold a sword in hand is better.
explain, please

Rotating the sword around the X axis is like drilling a hole with the tip. The moment of inertia around this axis is small and neglectable an, I think it depends mostly on the size and mass distribution of the crossguard.
The other two moment of inertia is almost the same, but you usually hit with the edge, not with the flat of the blade.
Moment of inertia is rotational inertia. While thrusting you do little or no rotation, I think here has a more important role the overall mass of the sword, and a good tip control.

The sword is not just rotating around a certain pivot point, it has a much complex trajectories which depend not only on the characteristics of the sword, but on the swordsman too, and his techniques.

Well you could say that the moment of inertia around X is significant for example with a rapier, changing from second (fingernails down) to fourth (fingernails up). I don't think the moment of inertia would normally be big enough to slow someone down significantly with such moves, though I can't say I have much data about that. From this perspective you would want a very short cross with branches tapering away from the blade, but usually you can find long crosses with weight added on the end, so there must be other reasons...

For now, I think the shape of the cross is determined by tactical imperatives (long quillons can bind the opposing blade) and decoration, but not really by physical considerations. On the other hand, the moments of inertia around the other axis are significant even for thrusting weapons: when you move the weapon to point it somewhere else, disengage, etc. you feel those.

From the practical point of view, the main problem with studying the moment of inertia around X is that we have no easy way to measure it on existing swords, thus little or no data.

Regards,