Potato Cannon

Synopsis

Potato cannons are simple illustrations of pressure, a vital part of chemical engineering. Potato cannons can operate on a number of principles, most revolving around an increase of pressure behind the potato at the base of the barrel which is pushed up the barrel, gaining speed until it exits the barrel.

Pressure is the force exerted on an area. We feel atmospheric pressure exerted by the weight of the air above us every day. Pressure is produced in potato cannons by either pumping extra air into the chamber, like a tire, or by igniting the fuel in the chamber of the cannon which heats the chamber contents and increases the pressure.

Chemical engineers use pressure to move fluids from place to place. Pumps are part of almost every chemical system. They add pressure to a fluid which then flows to an area of lower pressure in order to relieve the pressure the pump gave them. Typically this is down a pipeline to another tank or reactor. In the potato cannon the pipe is the barrel and the open air is the tank. Pumps add pressure by pushing against a fluid with spinning impeller arms or blades. This energy is converted into pressure when the fluid is forced into a smaller pipeline.

Safety: This project uses dangerous projectiles. Do not fire the cannon towards people or property.

Equipment

Cannon chamber, plug, and barrel (PVC pipe works well)
Potato
Ramrod
Fuel (hairspray or air)
Ignition source (if combustible version)

Instructions

Use PVC fittings to connect the chamber and barrel
Attach the ignition source to the chamber plug and seal the connection to prevent the pressure from escaping around it
Push the potato down the barrel with the ramrod
Spray hair spray into the chamber
Insert the plug and ignite the mixture