Postby GeorgeHill » Tue Feb 01, 2005 11:51 pm
I do not know if balistic gel would be good with swords. I do know why they use it with bullets.
The idea is that it streaches and flexes like flesh, and has the same cosistancy. If you shoot someone with a bullet, especially a hollowpoint, what happens is that you get two differnt wound cavities.
One is the perminate wound cavity, which is the bullet hole you still have when you get to the hospital. It's the same size as the bullet, give or take. A hollow point increases in diameter as it passes through flesh, and will have a larger exit hole then entry hole. A rifle at close range may actually produce a chunk sized exit hole.
The other is the temporary wound cavity. The temporary wound cavity is much larger the the perminate one. This is basically produced by strech. A bullet, even a pointy bullet, is realitively blunt. IT's just moving so fast that it penetrates. Now, If you stab someone with a dagger, it cuts into them, and makes a hole it's size and shape. If you shoot someone with a bullet, it's more like you rammed a bar clean through them. This produces 'streach' in the flesh. The temporary wound cavity is a very large hole that only lasts an instant, but it can disrupt nearby tissues, and some belive it is more important in producing an 'incapasitating' wound then is the perminate wound cavity, espeically if it stressed nerve tissue.
The last time I was reading up on this, conventional wisdom in firearms had decided that the temporary wound cavity was not actually that important, but that may have changed since I was doing my reading.
Balistic gelitan is very useful in measureing temporary wound cavities, but it's also useful in measuring bullet penetration. Ideally, you want a bullet that is moving really fast, but does not exit an adverage sized human body. You don't want it hitting someone behind the bad guy, and you don't want it exiting for another, more important reason. You want all your energy dumped into the target, or the enegry is wasted. (This is another place where the temporary wound cavity comes in.) The usual method is a hollow point, or a soft point, which expends the diameter of the bullet. Other methods are soft points, which do like wise, fragmenting bullets, which break the bullet into peices on impact, and with the M-16 and AK-74, bullets that turn on their side and fragment, and which change their center of gravity and spiril in strange directions inside the body respectively.
The channel of the bullet, where the bullet ends up, how deep the bullet goes, how many peices the bullet is in, and the size of the perminate and temporary wound cavities are easiest to measure with the gel, as it is clear. You can also photograph the bullet as it travels, and observe the temporary wound cavities with highspeed photography.
Balistic gel does NOT take into account bones, heavy clothing, etc.
Since we are more interisted in test cutting, or measuring the overall wound size in meat, I don't see it as that useful for sword scholars.
What mihgt be very useful to us is to put large bones into balistic gelitan, and to hit them with a sword whilst taking pictures with a highspeed camera.
