Dynamics, Sweet Spots, and Handle Mods

[MikeJackmin]

Here is a really interesting paper on sword dynamics; it's a bit long, but applies to pretty much any sort of swinging tool, from a stick to a sword to a khukri:

http://www.thearma.org/spotlight/GTA/motions_and_impacts.htm

I read it twice, and think I understand some of it.

My impression - if I am reading it right - is that the sweet spot can be moved forward by removing mass from the butt of the handle. Is this correct?

 

[OldPhysics]

Here is a really interesting paper on sword dynamics; it's a bit long, but applies to pretty much any sort of swinging tool, from a stick to a sword to a khukri:

http://www.thearma.org/spotlight/GTA/motions_and_impacts.htm

I read it twice, and think I understand some of it.

My impression - if I am reading it right - is that the sweet spot can be moved forward by removing mass from the butt of the handle. Is this correct?

I don't need to read the article to say yes. It's just basic physical dynamics ... if you remove mass from the butt or place more mass out on the end, the point of percussion will move further out from the butt.

 

[Cpl Punishment]

IMO you also have to take blade geometry into account. For instance on a blade like a kukri, which is heavily weighted in the belly area, a lighter butt will not move the sweet spot as far forward as if it were a blade that tapered allt he way to the end like an Uddha. Again, just basic physics. Which is why, IMO the weight of a chiruwa style handle doesn't make as much of a difference as some may think on a kukri.

 

[OldPhysics]

IMO you also have to take blade geometry into account. For instance on a blade like a kukri, which is heavily weighted in the belly area, a lighter butt will not move the sweet spot as far forward as if it were a blade that tapered allt he way to the end like an Uddha. Again, just basic physics. Which is why, IMO the weight of a chiruwa style handle doesn't make as much of a difference as some may think on a kukri.

Very true. Moment of inertia is the key thing, and geometry is part of that.

 

[Skyler R.]

Blade geometry plays a great part of the point of percussion as well as how the blade was intended to be used. For instance, a katana will not have the same point of percussion as say a european long sword even if they are the same weight and length. This comes under how the blade was to be used, the monouchi (area on a katana that is used to cut with, just below the yokote, or start of the tip) is fairly close to the tip while on a long sword the point of percussion on a long sword could be 6 inches or more back from the tip. Considering that most kukris are used for chopping I think that they offer a third area next to the two with swords.

Anyway..yes the sweet spot can be moved forward with more weight at the butt, but this can defeat the reasoning behind having the blade do the chopping for you.