How to Make a Water Rocket Brainiac

Create a high flying, water-shooting bottle rocket to thrill your friends or students.

"Brainiac" is an online video series displaying a series of science experiments. One of these is the water bottle rocket experiment. Partially filling a large water bottle with water and pumping it with air causes it to fly straight up into the air, to distances of over 100 feet. This experiment uses the principle of action and reaction to show how rockets function.

Things You'll Need

• Scissors
• Hard cardboard
• Tape
• Large water cooler bottle
• Water
• Air pump
• 10-foot air hose
• Plastic tube narrower
• Small blanket

Instructions

1. Cut out a cardboard fin a few inches shorter than your water bottle, and between 4 and 5 inches in width. The fin must come to a triangular point at the bottom, where it will touch the ground. Use this fin as a template to cut out two other fins.

2. Tape a fin to the bottle using strong tape so that the bottom part of the fin is at the same end as the opening in the water bottle. Repeat this procedure with the other two fins. This will form a tripod for the rocket to stand on prior to launch. Stand the water bottle on the tips of the fins to test whether it will support the bottle. Add more fins if necessary.

3. Fill the bottle one-third of the way full with water.

4. Insert the tube narrower into the end of the bottle. Attach the air hose to the tube narrower. Check to make sure the fit is as tight as possible so air or water does not escape. Connect the other end of the air hose to your air pump.

5. Turn the bottle over to see if water spills out. Adjust the end of your air hose until no water escapes by pushing it in more tightly. Place tape around the end of the air hose if necessary to prevent the bottle from leaking. Turn the bottle back over and set it down.

6. Fold a small blanket several times and place it on the ground. Stand the bottle rocket on its fins. Put the end of the air hose on the blanket for support. Stand as far back as possible and pump air into the bottle. Keep pumping until it takes off.

Tips & Warnings

• Make sure your bottle rocket is standing up straight before pumping it with air. If it is leaning or falls over, it could fly off in a random direction and cause damage or injury.

• Only perform this experiment in an open space with no buildings nearby.

• Wear safety gear, such as hard hats, heavy coats and other safety goggles while performing this experiment.

References

• Vinod Kram: Movie Physics Forces Water Rockets Brainiac