2001-01-25 – PowerBands

Here’s an idea. How about a (desktop) computer system that doesn’t crash at the most inconvenient time possible? I know it’s nothing new, but hey… (Note: our server died a few days after I wrote this, and this laptop crashed, and lost all todays [04/03/01] changes.. MicroSux! Argh!!)

To paraphrase my earlier idea: last Thursday I was playing with my catapult, which is a Barnett Black Widow, and an interesting thing occurred. I was firing both .38 steel balls and slightly larger plastic BBs, both also produced by Barnett.¬† When firing, the little leather pocket that holds the ball tapped lightly against my fingers. However, when I fired the plastic balls the leather pocket hit my hand quite violently. When the bands were stretched fully to arm’s length and fired with a steel ball the same thing happened and firing the plastic balls was downright painful. It occurred to me that the limitation was the speed of contraction of the band, and how much energy was transferred into the projectile. With various projectiles of slightly differing weights fired through a chronograph to measure the speed one could plot the energy against weight. This would give a peak at the optimum projectile mass, the theory being the speed of the projectile can only go so high from an elastic band, no matter if the mass is further reduced. At this point the further reduction of mass causes a drop in output power. Of course, too heavy a mass will mean that your speed is too low, and since K.E.=0.5*mv2, that wastes energy, which goes as heat in the bands, and in slapping your fingers! This theory should hold true for crossbows, all non-firearm projectile weapons, and even javelins. This might make an interesting project, along the lines of developing¬† (“working up”) a load for your rifle.

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