For those who don't know my senior design team has designed and is building a waterballoon launcher. We finally constructed it to a point that we pressure-tested our receiver for leaks, and we dry-fired our cannon today (about 8 shots). We put it on its frame and rolled it outside, aimed it down the waterfront road, and fired a few empty barrel shots. Man it's awesome making something that SOUNDS SO COOL (and works). Then just to be ornery, we stuck a lil plastic ball (about the size of a tennis ball- our barrel is 6 inches in diameter...so the air might have just rushed past it...), and it launched the ball almost 200 feet!
We're going to take pictures tomorrow and start test-launching actual waterballoons.
Well, today we painted everything black then we test-fired a waterballoon with our protective/sealing cradle and it worked! We first tested it at 40 psi and our gate valve 1.5 turns open, the line that prevents our cradle from going downrange held but the waterballoon only went about 30-40 feet. We then tested 60 psi with the gate valve 3 turns open, and the waterballoon went about 100-130 feet...but the line that held our cradle snapped :(
Back to the drawing board for that!
Well we got the cable to hold, but then the cradle was destroyed by the jerk at the end of the line. We ended up using a parachute idea. We made a parachute out of tarp and attached it to the back of our slider/cradle, and just sending it freely down the barrel. Today we tested a number of different firing pressures, keeping our gate valve fully open, and recorded distances, then we held our pressure constant at 40 psi, then throttled down on our gate valve to get the accuracy shots of 25, 50, and 75 yards.