In a previous post of mine, I wrote about a modification to lead sling projectiles that allowed for a low-pitched buzzing sound in flight. This modification involved cutting notches vertical to the length axis of the projectile along the sides of a 4 oz lead fishing weight.
Someone mentioned that the notches may give the projectile additional lift. I gave that statement a lot of thought and came up with something. I purchased a bag of 4 oz lead weights that had a tiny hole drilled along it's length(to insert the fishing line). I cut the 4 standard notches, 2 on either side of the football-shaped weight. Only, instead of the notches being vertical, I made them diagonal to the length axis of the football.
So basically each notch began on the outer edge around the middle of the football, and converged upon one tip of it. Then I hand drilled a tiny hole from the beginning of each notch to the shaft running along the center of the projectile. I thought that as the projectile is on the ascent stage of it's parabolic trajectory, air would rush into the central shaft from the upper tip of the football. When the air got to the middle of the football, some of it would pour into the four holes that I drilled and directly onto the notches that I carved on the surface of the football. The air would rush against the notches and converge on the bottom tip of the football. This would serve two purposes. The first is that the diagonal notches would cause the football to spin faster and thus lower it's cep(circular error probability). The second purpose is that the air rushing out of the bottom of the notches would exert force against the sides of the football, thus giving it abit of extra lift during the ascent stage. I thought I had recognized my error after I made the projectile. I thought that if the notches provided lift for the stone on the ascent state, surely the same notches would speed up the stone on the descent stage and thus negate any advantages of extra lift.
But with a stone already made I decided to test it out for kicks. So on friday, I took my medium sling and the stone with me on a fishing trip. The lake that I fished in has a small island near it's center. Using my laser range-finding binoculars, I ranged the distance from the shore where I fished to the island to be 310 meters. Now normally, I would be able to cast a leadweight out to about 140-150 meters max. Now this modified projectile, once leaving the pouch, flew way up, much higher than the unmodified weight. There was no buzzing sound, but that was expected since the notches weren't designed to resist the air pushing against it. The flight was extremely smooth(almost like a rifle bullet), I didn't see any wobble on the tips of the projectile. Now that looked very odd, since it was as if the stone was flying through the air without any movement upon itself. The projectile flew until it became a tiny dot in the sky and then it descended. It appeared to me that the projectile struck the waters very close to the island. Using my binoculars, I ranged the ripple pattern that the stone made. The distance ranged was from 278 meters to 291 meters depending on where on the ripple the laser was hitting. Taking the average of these two values yielded 284.5 meters, that's about double the range on a normal projectile. That's longer than any stone that I've ever casted with any sling.
Now with this in mind, I'm making a few more of these projectiles. My heavy sling was able to cast a normal lead-weight out to 195 meters. If this works, then maybe these projectiles of mine will travel out to nearly 400 meters with that sling. I'll post the results.
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New Pictures--Range Boost (Read 21535 times)
