Balloon Rocket Engine
Rockets, jet engines and spaceships are all driven forward by the same principle: every action has an equal and opposite reaction. This means pushing something out of the back of a rocket will give the rocket a forward push of the same force. In the case of rockets and jet engines the material pushed out the back are the hot expanding gases from the burning of jet or rocket fuel.
You can build your own "cool" rocket engine by using air stored under pressure in a balloon. When the air is released it will give your rocket a forward thrust.
What you need
- Tape
- Clothespeg
- Straw
- Scissors
- Scrap paper
- Cereal box (or stiff paper)
- Paper or plastic cup (optional)
- Balloon (long skinny ones work best)
- Long piece of fishing line (or smooth string)
- Bottle cap or marble (to use as cargo)
What to do
Step 1. The propulsion for your rocket will be an inflated balloon.
Step 2. Build your cargo container from materials such as paper, a cereal box, or a paper or plastic cup.
Step 3. Your rocket will travel along a piece of fishing line, which is threaded through a straw on your rocket. Remember to include the straw somewhere in your design.
Step 4. It is up to you to find the best way to attach the cargo container to the straw and the balloon.
Launching Your Rocket
Step 1. Blow up your balloon and use the clothespeg to hold it closed.
Step 2. Tape one end of the fishing line to a wall about chest high. Hold the other end in your hand at approximately the same height.
Step 3. Load your cargo (bottle cap, marble, or any other small, light object) into the container.
Step 4. Thread the fishing line through the straw attached to your balloon rocket.
Step 5. Unclip your clothespeg and watch your rocket fly!
What's Happening
When you blow up a balloon, you force air into a small space. Air particles don't like to be squished (engineers call it "compressed"). The particles want to move to a less crowded area. When you let go of the clothespeg, the air in the balloon rushes out to the lower pressure (less crowded) room. All that air rushing out the back of the balloon pushes it forward. Remember, for every action-air rushing out the balloon opening-there is an equal and opposite reaction-the balloon rocket shooting off down the fishing line.