These two easy-to-make launchers use ring-vortices, or "invisible smoke rings" as their "ammunition." Experiments to be done with adult supervision.

SMALL VORTEX LAUNCHER

Materials

• empty soup can
• can opener
• cardboard
• thin card stock/heavy paper OR a balloon (better)
• tape
• scissors
• stick incense (optional)

Procedure

• Use the can opener to remove both the top and bottom of the soup can. Be careful of the can's sharp inside edges!
• Cut a disk from the cardboard to fit one end of the can.
• Cut a 1" hole in the center of the cardboard disk.
• Tape the cardboard disk over one end of the can.
• Cut a disk from the card stock/heavy paper to fit the other end of the can and tape the disk to that end

OR

• Snip the balloon in half, stretch the balloon half across the other end, and tape it in place.

                    _________________________
                   /                        /\
                  |                        |  |
                 |        SOUP CAN        |    |
                 |                        |    |
                |                        |      |
                |                        |  __  |       CARDBOARD 
  BALLOON       |                        | (  ) |  /___  WITH 1"  
    OR     ___\ |                        | (__) |  \      HOLE     
 CARD STOCK   / |                        |      |    
                |                        |      |       
                 |                        |    |
                 |                        |    |
                  |                        |  |
                   \________________________\/

Experiment with Your Vortex Launcher

• Gently tap your vortex launcher on the end without the hole.
• An invisible ring of spinning air will shoot out of the hole on the other end.
• Aim the device at your face or arm, and you'll feel the puff of air when it hits your skin.

To make the vortex rings visible using smoke:

• With an adult's help, light the stick of incense.
• Being careful not to burn the cardboard, place the smoking end of the incense stick into the cardboard disk's hole and allow the smoke to fill the can.
• Remove the incense stick, then gently tap the end without the hole.
• Slowly spinning smoke rings will be launched.
  Note: If you tap the end hard, the smoke rings will zoom so fast that you'll only see a grey blur. If you tap it even harder, you will generate air turbulence but no smoke rings.
  Fun Fact: A smoke ring is similar to a tornado, but the ends of this "tornado" are curved around so they join into a circle.

Hints

• To see the details of the smoke rings, it helps to use a bright light against a dark background.
• Work in a darkened room while facing a bright table lamp.
• The light should shine toward you, through the smoke.
• Position yourself and the lamp so you can observe the smoke against a darkened wall.

Things to Try

• Shoot slow smoke rings, then immediately shoot faster ones. The faster ones will catch up to the slower ones and move through them (the slower ones open wider to allow the fast ones to pass).
• Use scent rather than smoke:
- Any scent inside the can will end up inside the air in the ring vortices.
- Spray some perfume in the can, then launch your ring vortices at a distant nose.

Hints for the Science Fair

The vortex launcher is a cool physics demonstration, but how can we convert it into an experiment? Easy:

• Ask a question.
• Change your question into a statement (hypothesis).
• Perform an experiment to either prove or disprove your hypothesis.

• Ask the question, "How far can a 4-inch vortex launcher send a ring vortex?"
• Change this into a hypothesis: "A 4-inch vortex launcher can project a smoke ring across xx centimeters."
• Conduct your experiment, and find out what xx equals.

Be original! Think up a weird and interesting question for which you do not know the answer.

Note: Be sure to get staff permission before using any kind of smoke indoors at the Science Fair!

GIANT VORTEX LAUNCHER

Materials

• old plastic garbage can
  
• plastic lid for garbage can

OR

• a plastic garbage bag and duct tape (to replace the lid--works just as well if not better)
• cutting tool

Procedure

• With an adult's help, cut a 6" circular hole in the center of the garbage can's bottom.
• Put the plastic cover on the garbage can

OR

• Secure the plastic garbage bag over the open top of the garbage can with the duct tape to form a sort of "drum head."

                    --------------________________
                   /                             /\
                  |                             |  |
                 |    PLASTIC GARBAGE CAN      |    |
                 |                             |    |
                |                             |      |      6" HOLE
   PLASTIC      |                             |  __  |          CUT
 GARBAGE BAG    |                             | (  ) |  /___ IN THE
      OR   ____\|                             | (__) |  \    BOTTOM
   CAN LID     /|                             |      |     
                |                             |      |       
                 |                             |    |         
                 |                             |    |
                  |                             |  |
                   \              _______________\/
                    --------------

Experiment with Your Giant Vortex Launcher

• Whack the cover or "drum head" to launch invisible air vortices.
• For the Science Fair, come up with a hypothesis about the power or distance capabilities of the invisible air vortices launched by your Giant Vortex Launcher, then prove or disprove your hypothesis.

Used with permission of William Beaty.

Be sure to check out our Science Fair Project Books and Kits too. You'll find plenty of exciting projects and ideas for budding young scientists!