A balloon rocket is threaded through a long string and will fly across the room with the help of propulsion. We learned how to make it from Arvind Gupta’s Toys from the Trash. Rocket engines are reaction engines explained by the Newtonian Principle’s Third Law “to every action there is an equal and opposite reaction.” A rocket engine is throwing mass in one direction and benefiting from the reaction that occurs in the other direction as a result. When you blow up a balloon and let it go so that it flies all over the room, you have created a rocket engine. In this case, what is being thrown is the air molecules inside the balloon. Many people believe that air molecules don’t weigh anything, but they do. When molecules are thrown out the nozzle of a balloon, the rest of the balloon reacts in the opposite direction.
Tools and Materials:
Paperclip or Wire
There are two straws in this rocket design. One is to thread through the string to enable the rocket to fly across the room. The other is to attach and blow up the balloon. It is very important when you’re designing your rocket to make sure that it is easy to thread a string through the ”string straw” when your rocket is glued shut. This means that string straw should be visible, from both ends, when enclosed in the paper.
Step 1: Fold a sheet of paper in half and draw your rocket body. Cut it out.
Step 2: Place a ruler next to a drinking straw, measure and mark three inches on the straight end. Cut it. This is your “string straw.”
Step 3: Next, apply glue in the centerfold of the rocket.
Step 4: Place the string straw on the glue.
Step 5: Place the bent straw next to it.
Step 6: Secure both straws with two small pieces of tape.
Step 7: Glue the rocket shut.
Step 8: Attach a balloon on the bent end of the straw with a rubber band or electrical tape.
Step 9: Bend a paper clip straight or take a stiff piece of wire and tie the string to it. The knot should be small enough that the clip or wire needle will be able to pull the thread through the straw.
Step 10: After threading the rocket on the string, get a friend and pull the string tight across a room. Blow up the rocket on the string. Hold the end with your finger to keep the air in the rocket until you are ready to let go. Watch it fly across the string.
Step 11: Redesign. How far did your rocket go? If very far, congratulations. If not so far, consider the factors (e.g. weight, friction, amount of air) that slowed it down. Fix it and try again.
Step 12: Build rockets with friends and race them side by side on many strings!
Note: Step 1 gives a suggestion for a very simple rocket design. Some of our Maker Kids made rockets by folding paper into very intricate paper airplane designs. Anything goes! You engineer the plane that flies the best!
Links: Arvind Gupta Toys From Trash balloon rocket http://www.arvindguptatoys.com/toys/balloonrocket.html