How To Build A Potato Cannon
For the adolescents at play, having a good potato cannon at hand can be a fun way to spend some time outdoors. And for those parents wishing to give their kids practical lessons, a potato launcher is a fun demonstration of many of the principles of physics.
Below, we’ll show you how to build the most basic potato gun, consisting of a combustion chamber, a barrel, and an igniter.
Step 1: Cut Your Pipe
Your 3-inch PVC pipe will be your combustion chamber. It can be anywhere from 6 inches to a foot in length. The 2-inch PVC pipe is your barrel. Take the time now to cut all your pipe to the appropriate length.
Remember, just as in regular fire arms, a longer barrel ensures greater accuracy, but the longer it is, the less force it will have. Two feet is a good barrel length, but you can choose to adjust it to your needs as you experiment.
Step 2: Attaching Chamber And Barrel
With the 3-inch PVC slip, attach the end of your 3-inch pipe (the chamber) to the 3-inch end of your reducer. Attach the other end of the reducer to your 2-inch pipe.
Step 3: Setting Up For A Spark
On opposite sides of the chamber, directly between each end, screw your drywall screws into the 3-inch PVC pipe. Screw each in so there is a small amount of distance inside between the tips.
Attach your BBQ igniter to the ends of your screws. This will essentially be the trigger you pull to fire your cannon. Test it now; if there is a spark, your screws are good to go. If there isn’t a spark, move your screws closer together inside the chamber and test again until you get the right distance.
Step 4: Seal It Off
Using PVC cement, make an air-tight seal around the 3-inch PVC pipe and the 3 to 2-inch reducer, as well as around the 3 to 2-inch reducer and the 2-inch PVC pipe. Also, cement around your screws to be sure they stay in place and remain airtight. Allow plenty of time for the cement to dry.
Step 5: Bevel The Barrel
Use a dremel tool to bevel the end of your 2-inch barrel, making the ends sharp. This way, your potato will be cut to size as you load it into the barrel. Also, with the skins removed, the juice from inside the potato will help your potatoes fire more smoothly. If a dremel tool isn’t available, use a regular file to create your bevel.
Step 6: Propellant
Hairspray makes a quick, easy, and cheap propellant. Pure propane can be used, if available. Remember when adding propellant to your chamber that in order for combustion to occur, there needs to be a good mixture of air as well. Place the cap on the end of your 3-inch pipe, and use the dowel as a muzzle loader to push your potato down to the other end of your barrel.
Simple as that! More complex versions are possible, of course, and even this design can be tweaked for optimum performance. Now go out and fire some potatoes!