Weird Science

HONOLULU (HawaiiNewsNow)-Dr. V Show:  Soda Bottle Rocket Launcher

Things you will need:
•    2-liter clean plastic bottle
•    ½ inch diameter flexible tubing, about two feet long
•    Duct tape (or other strong, flexible tape)
•    ½ inch diameter PVC pipe, one foot long
•    8 ½" x 11" sheet of construction paper or cardstock
•    Tape
•    Scissors
•    Index card
•    Ruler
•    Pencil

The Experiment:
Take the cap off the bottle and put the flexible tubing into the neck of the bottle. Then seal it tight with the duct tape so that air doesn't escape. Put the PVC pipe up against the tubing and make another airtight seal with the flexible tape. Now you have your launcher. To built your rocket, make a tube by rolling the paper the long way around the PVC pipe, loosely so that it slides off easily. Slide the paper tube off and tape it along the seam so it holds its shape. To make a point at the top of your rocket, flatten out an inch or so of the tube at one end. With the scissors, cut the flattened part to a point, or slightly flatter than a point, to be safe. Then tape the edges together to make as tight as seal as you can so that air doesn't escape from your rocket. If you'd like to add fins to your rocket, cut your index card in half, and then diagonally to form four fins. Tape the fins to the bottom of your rocket at equal distances. Now slide your rocket onto the PVC pipe. Place the 2-liter bottle on the ground and face the PVC pipe with the rocket on it upwards and away from people. Then STOMP down onto the bottle and BLAST OFF!!

How does it work?
If you built your rocket launcher and rocket with airtight seals, your rocket should fly pretty high. When you press your food down onto the bottle, you are forcing the air out of the bottle and the only place the air can go is into the tube, up the PVC pipe and into your rocket, which get pushed upward. Because the rocket has a pointed tip, there is less air resistance, as the air flows past the rocket. This helps your rocket fly farther. The fins give your rocket stability so that it will fly straight.

Try making a rocket with no fins. How does it fly?
Try making a longer rocket, or making a rocket with a different shape nose. How does it fly?