patriqq-
I hope I'm not discouraging you with this stuff; by all means get out there and create something! That's far better than sitting and just thinking about it. But I'd encourage you to keep an open mind, and evaluate your prototype's performance with honesty and as little bias as possible.
However, the pommel is just an addition of more mass. I want to keep the overall mass as low as possible.
No, the pommel is not just another lump of mass. It can greatly change the impact dynamics, giving you added cutting power near the tip for practically free. (if done properly)
I am interested; but I think experience and experimentation are the last word.
I also am speaking from experience, coupled with experimentation. For example, check out
this thread where I apply these principles to increase the performance of my khukri.
Do all the math you want, there is a simpler place to look. Consider historical designs from type of blade you are trying to build. Aboriginal technology often proves more clever than anything a group of engineers can design.
Yeah, the first thing that came to mind here would be something like a bolo or somethin', to fill the stated requirements. The only edged tools I can really think of that have a mass distribution more like a hammer, are hatchets and axes. It doesn't seem like this idea of making a knife with a bunch of mass clustered at the very end has proven worthwhile that I can think of. Likewise there are plenty of swords with pommels, and plenty without- optimized for different applications.
I see hatchets being mentioned as poor at brush clearing because of a lack of acceleration. Undoubtably this is true, but it isn't the only, or even the main, reason hatchets aren't optimal for this work. The thickness of the blade pays more of a role than the rate of acceleration, from my experience. The length of the cutting edge also plays a large role.
I figured the cutting edge length would be kinda obvious, but have to disagree on the thickness being more important than accelleration. My Wetterlings hatchet has a nice thin edge; not appreciably thicker than most chopping knives. And when you're cutting through plants only 3/8" thick, the thickness of the poll never comes into play. Tough weeds like greenbriar, wild (multiflora) rose, etc., really depend on speed to get through. Even with nearly full arm swings, a hatchet has real trouble lopping them off. And you'd really wear yourself out trying to keep that hatchet moving at max speed. Conversely, a lighter brush knife can snick them off with just a flick of the wrist. I pretty much agree with most of the rest of your post.
a knife is not a hammer, at least it shouldn't be. The balance is different. If you were to put a pommel on the lead hammer, you'd get a better swing at it and drive nails faster.
I haven't explored the details of the impact mechanics of hammers/axes, but right off the bat I'll bet you a dollar this wouldn't work. If it did, then the tool we call a hammer today would have included a large counterweight at the back of the handle for the past millenium.
Speaking of impact(which is the same as momentum)
Quote:
F (force) = m (mass) x v (velocity) ^2 (squared)
I might be misinterpreting you here, but thought it would be prudent to point out something with an example. If you swing a straight steel rod, equal in mass all along its length, where do you get the most impact power? If you're being too simplistic with the above equation, at first it would seem that the tip should strike with the most energy. After all, it has the same cross section (mass at that point) as the rest of the rod, and it's moving the fastest. But this is not true. The tip's inertia is only 1/4 of the rod's mass. It is 3/4 of the rod's mass at 1/3 back from the tip. Anyone who's spent some time whacking stuff with sticks and staffs should recognize this immediately. Just pointing it out to keep folks from getting side tracked or getting misconceptions...
