Quote:
Originally Posted by snotsdelta
My Team has constructed a T-shirt Cannon, which got tested for the first time today. We had a very anticlimactic result has the T-shirt basically just fell out of the end of the tube. We are using the KOP pneumatic system connect to about 1.5 foot ABS tube. The tube has a inside diameter of 3". I know we do not have enough pressure behind the T-shirt. I was wondering if a smaller diameter tube would fix this issue? We have our pressure built up to 110psi, which I thought would be enough to at least get 20 yards. Any help on this would be greatly appreciated!
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I'll save my lecture about using plastic as a barrel for a later thread.
Your pressure is not the issue. 110PSI is overkill. What your issue is ... is flow and reserve air.
Gas (in this case, air) expands to fill the area (universal gas law). It only takes a few pounds of force to overcome the friction if the t-shirt to the barrel. Once that happens the t-shirt begins to move up the barrel, increasing the volume that the air needs to fill and dropping the pressure in the barrel. You need a flow rate that is higher than the expected volume increase as the t-shirt moves up the barrel and enough of an air reserve to sustain that flow rate throughout the entire firing time.
If you don't have enough air flow, or enough reserve air to fill the entire barrel at the pressure you want, the t-shirt will not fire very far ... and will tent to just drop out of the barrel rather than fire out.