Quote:
Originally Posted by Rob2713g
Ours doesn't launch with lots of power. At a 45 degree angle and 110PSI, a shirt goes approximately the height of a 2 story house. Last Thursday, we tested it by first hitting a mostly empty trashcan, which it did not knock over (but did rock). One of the parents then volunteered to get hit at close range (10ft) and was fine. Then some kids got hit at catching distance and were fine. The lack of extreme power in our launcher may be due to the barrel being so much larger than the tank and the shirt not being too tight in the barrel (allowing air around it). We'll try to be careful and scrap the plans if it looks dangerous.
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110psi = Lots of pressure. I wouldn't go above 60, or hell, anything above 1 bar with PVC (1 bar = average atmospheric pressure, 14.7psi).
Keep in mind, the short length of the barrel is why your launcher isn't "powerful". Firearms can acheive higher projectile speeds with longer barrels because of the physics involved, and the same thing is applied here. The longer barrel means that the projectile (in this case, a shirt) has pressure applied to it for a longer time. The short barrel means that the shirt gets a quick blast of pressure (which I'm sure some of it is lost because I'm assuming you don't put the shirts in a break-away casing that would create a better seal) before the air can escape the barrel and dissipate, no longer imparting it's energy upon the shirt.
Now, for a much safer system...
Use the FIRST air tanks and mount them to a dedicated launcher-bot (simple frame, tank drive, 2/4 air tanks, etc) that has a pneumatic system for an ARM instead of a cannon. Do the math and figure out the general trajectory of the different pressures (one bar at a time, ie 15psi, 30psi, 45, 60, 75, 90, so forth) as well as the boom ratios (1:2 ratio? 1:3? What can your pneumatics handle? How well does it work?) and such.
This way you know the trajectories it launches at, about how far and such, and it's as controlled as it can be every time.
-Otaku