geniusbomberman wrote:I am thinking of making a large( 4 or 5 inch) barrel, and I want to know what would be good ammo for it. Do hardware or craft stores sell Styrofoam or wood cylinders that are this size, because that would be good. An obvious solution would be to take a piece of the next smallest size pipe, slightly make the bottom of it wider with the standard method and make PVC rockets. Would the projectile have to be pressure rated at all? This is for a combustion cannon.
4 inch will fit 4 inch round poof brand foam balls and camping stove propane cylinders. Small grapefruit, large oranges and other produce is lots of fun.
5 inch is an odd size. 2 liter pop bottles would work, but the fit isn't the greatest. Cantaloupe small gourds and pumpkins are good for 5 inch to 12 inch cannons.
Depending on the pressure used, it does pay to figure out the recoil forces before launching heavy large diameter stuff. 100 PSI on a 3 inch barrel can push an object at over 700 LBS.
Tread carefully when working with larger diameters.
How long have you been spudding?
Maybe I read your question wrong. Do you mean 4 or 5 inches long?
If so wooden dowels 2 inches and smaller in diameter are common and can be found in lengths exceeding 4 or 5 inches.
It is hard to find ammo for stuff over 3 inches in diameter. It gets expensive.
Use the math for the area of a circle and multiply the area times the pressure of combustion to get an idea of the expected recoil impulse force. In round numbers use 35-100 PSI. It varies between spray and pray and metered propane.
Area of a circle is Pi times radius squared. 5 inch has a 2.5 inch radius. Radius squared is 6.25. That times Pi (3.14) is about 19 square inches. If you have a heavy projectile and a 100 PSI combustion pressure rise, the force is 1900 Lbs. It's a Ton of force in round figures. Care to hand hold that cannon? Please be careful.
