Giant Smoke Ring Vortex Cannon | Science Experiment
How to Make Giant Smoke Rings with a Vortex Cannon
Create giant smoke rings with a few supplies you likely have around your home. This fun, hands-on experiments reveals the path of an air vortex shot from a garbage can. Pretty cool, huh?
Toy manufacturers sold small air blasters that sent vortexes of air sailing across a room, which surprised innocent victims and delighted (not-so-innocent) spectators. With a little practice, it was easy to shoot a plastic cup off someone’s head or ruin 20 minutes of hair styling from across the room. It was a blast — literally! The Steve Spangler Science motto is: “Make It Big, Do It Right, Give It Class!” This mission resulted in the creation of our Trash Can Smoke Ring Launcher. In this air vortex cannon experiment, you’ll learn how to create a smoke vortex in your home or classroom. It’s easier than you think to make an air cannon.
- Large plastic bucket or trash can
- Bungee cord (5 ft, 1.5 m )
- Plastic shower curtain or thick plastic sheet
- Utility knife or keyhole saw
- Adult supervision
Turn a garbage can over and use a utility knife to cut about an 8-inch diameter (20 cm) hole in the center of the bottom of the can. The cut doesn’t need to be perfect; however, the more centered and circular the hole is, the more awesome your smoke rings will be. You can smooth and round the hole with a little sandpaper.
(A smaller version of this smoke ring cannon uses a 5-gallon [19 liter] plastic bucket. Cut a 2- to 3-inch [5-8 cm] hole in the center of the bottom of the bucket. Use care when cutting the hole with a knife or keyhole saw. Adjust the shower curtain and bungee cord as needed.)
A piece of plastic shower curtain works great as the membrane needed to make this homemade air cannon. It’s durable and flexible and can be easily trimmed with scissors or a utility knife. Shape it into a circle that hangs over the edge of the can (about 10″ [25 cm] all the way around). Secure it in place with a bungee-type cord. The plastic should be snug.
Point the hole in the bottom away from you and sharply hit the shower curtain with your hand or the end of a stick. An invisible blast of air shoots out of the hole. Aim the hole at someone or something across the room and send a blast of air their way with a swift whack of the plastic membrane. (Then smile and look innocent when they glare at you.)
To share the fun with your students or friends, hold the hole over a smoke source (such as a smoke generator or a smoke bomb) and fill the container with smoke. Point the hole away from everyone and tap in the center of the plastic to generate huge, rolling smoke rings.
How Does It Work
How Does the Smoke Vortex Cannon Work?
The correct name for this homemade air cannon and smoke-ring device is a “vortex generator.” The “ring” that shoots out of the cannon is actually a flat, vertical section of air. The outer edge of this moving air is rolling backward on itself. This vortex of air is generated because the air being expelled from the center of the hole is traveling faster than the air moving around the edge of the hole. The air around the edges takes longer to get out of the can. That swirling (or vortex) motion can be observed if a little smoke is added to the container before giving the plastic a tap. This activity demonstrates that air occupies space. The super-cool rolling smoke rings are an added bonus.
A Lesson in Bernoulli’s Principle
Bernoulli’s principle states that the faster air is moving, the lower its pressure. Since the air inside the vortex is moving faster than the air outside the vortex, the higher inward pressure from the outside air is the force that holds the smoke ring together. Eventually, friction steals away all the energy stored in the vortex and the smoke ring drifts to a stop and vanishes. Very cool, huh? Our do-it-yourself smoke vortex is a great way to incorporate a memorable and fun experiment into units about air and air pressure. Want more experiments that demonstrate Bernoulli’s principle of air pressure? Check out our One-Breath Bernoulli Windbags and amaze your friends by blowing up one of these colorful bags with just one breath! We also offer a whole host of other experiments that demonstrate chemistry, biology and earth science, physics and more!
Take It Further
You can take this amazing air vortex cannon lab further by identifying a variable, or something that changes, in this experiment. Let’s take a look at some of the variable options that might work:
•Modify the size and speed of the rings by changing the size of the hole
•What happens if the hole is not round? Try different shapes and find out
•What happens to the rings if the sides of the can are not sloped toward the hole
These are just a few ideas to put a different spin on this homemade air cannon experiment, but you aren’t limited to them. Try coming up with different ideas of variables and give ‘em a try!
Science Fair Connection
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At Steve Spangler Science, we practice safe science — always. Whether you choose the traditional smoke machine or the much more exciting smoke bomb technique, the rule is the same: never blow smoke into someone’s face (either a person or an animal)! Aim these smoke vortex rings into the air only.
It’s also important to always perform this vortex cannon activity OUTSIDE only. Otherwise, be prepared for the smoke alarms to go off. It’s always interesting to have to explain your homemade smoke rings to a fireman who’s standing in your home or classroom in full firefighting gear. Been there, done that, don’t want to do it again. Trust us.
When you’re talking science, it’s important to use correct terms and to use them correctly. The plural form of “vortex” is either vortices [vor-teh-sees] or vortexes.
When you’re talking science, it’s important to use correct terms and to use them correctly. The plural form of “vortex” is either vortices [vor teh sees] or vortexes. Use the one you prefer.