Potato Cannon
 

Hi,

Our team is making a T-Shirt cannon. How would we simulate the firing of the cannon (air compressed), through solidworks?

Re: Potato Cannon
 

I don't have a good answer to your actual question, but we have spent spare hours for three years on a t-shirt launcher, which we finally got out to the games this year. It really helped our recruiting! Here's what we learned:

• Use large hoses/pipes from the accumulator to the barrel
• Size the barrel properly
• Make sure you can fit through the door of your build space
• Roll the t-shirts well

Hoses: we eventually wound up at a minimum of 3/4" diameter from the accumulator tank (about 3 gal, but probably didn't need to be this large) to the barrel, including the solenoid valve.
Barrel: We started at 2-1/2", but found that 3" was better, especially at shooting those foam rubber footballs. It also made shooting shirts easier. Make sure that you have a tapered transition from your smallest size to the barrel size to reduce losses to turbulence.
Fit: We messed this one up. We built a base chassis that would have fit with AM rubber-tread wheels, but when we went to the much-larger pneumatic wheels purchased at Harbor Freight, we couldn't fit through the door. We wound up rebuilding our robot during a four-week span of road games to be narrow enough to fit through our door without getting a couple of football players to carry it through sideways.
Rolling shirts: Some of our earlier attempts used duct tape to keep the shirts together through a launch, which makes the shirt rather less desirable in the stands. We developed a method that worked well for us and required nothing but the shirt itself to hold the package together:

• Lay the shirt out flat on a table
• Fold one sleeve over onto the body of the shirt
• pick up the waist hem and lift until there is a turn running from one armpit to the other
• come back down to leave the next turn at the shoulders
• repeat with armpit and shoulder until you've run out of shirt (usually five layers for a size L/G shirt)
• Roll the shirt up across the shoulders, starting at the side where you folded the sleeve under
• About halfway down the (short) sleeve at the end, flip the rest of the sleeve out over the cylinder you've created.