Introduction: How to Make a Water Bottle Rocket

Learn how to make a water bottle rocket step by step with an explanation of each component.
2)Create the basic body
5) Final Assembly
6) Reasoning


- 3 2L soda bottles
- Garbage Bag
- duct tape
- yarn
- cardboard
- tennis ball
- scissors
- ruler
-wiffle ball bat
- balloon
- Hole puncher

Step 2: Create the Basic Body

1) Grab one of the 3 2L bottles and set it aside.
2) grab another one of the 3 2L bottles you have  left and fill it up with air, then attach it to the end of a drill and rotate it over a hot plate until the bottom of the bottle begins to form a cone shape, cut 15 cm down from the top of the cone, this is going to be the top of your bottlerocket.
3) Grab the 3rd bottle and cut 7 cm down from the cap, then cut 4 cm from the bottom so that all that is left is the middle section of the bottle, save the top portion of this bottle.
4)Grab the wiffle ball bat and cut 9 cm from the base of the bat, take the top portion you have from the step above and tape the cap side to the piece of wiffle ball bat you have, this will hold your ball in place during launch.
5) Now grab the bottle you set aside in the beginning, this is your base, this bottle will hold the water that will project your bottle, take the piece of wiffle ball bat you have and tape the base to the bottom of your base bottle.
6) Take the cone and tape it to your middle section piece, at the bottom of this cut 3 cm deep slits 2 cm away around the base of the piece.
7) grab the balloon and fill it with enough air to cover 5 cm from the top of the cone and cut a circle the diameter of the balloon out of cardboard, tape these two together and tape the combo inside the top of the cone shape.

Step 3: FINS

1) take the cardboard and cut out 3 right triangles with dimensions 5x17. 
2) cut off 2.5 centimeters off of the top of each triangle,these are going to be your fins. 

Step 4: Parachute

1) take the garbage bag and cut out a circle with a diameter of 75 centimeters 

2)cut 8 pieces of yarn that are 75 cm.

3)place the circle flat on the ground

4)cut small pieces of tape and place them 9 centimeters apart around the circle. There should be eight placements of tape.

5)using a hole puncher, punch a small hole about 2.5 centimeters from the edge in each of the tape placements.

6)pull the string through the hole and tie a double-knot.

7)take the tennis ball and tape the end of all 8 strings to the ball.

8)Grab all 8 strings and twist and tape about 6 cm up from the ball.

Step 5: Final Assembly

1) Tape the fins equal length apart around the base bottle.
2) Fill 1/3 of the bottle with water.
3) Place the tennis ball in the top portion of the wiffle ball bat
4) Fold the parachute into the smallest dimensions possible
5) place the parachute near the bottom of the wiffle ball bat, leaving some slack on the yarn.
6) Place the cone shaped bottle portion over the ball and bat so that the ball pushes on the disc and balloon.
7) You are now ready for launch.

Step 6: Reasoning

CONE TOP: The cone top allows for the rocket to have less air resistance, it makes it more aerodynamic.
FINS: The fins also make the rocket more aerodynamic, they allow the rocket to soar through the air with minimal resistance.
WATER: The water is in the bottle so that when attached to the pump the pressure will cause the water to shoot out the bottle, this will cause an equal force to push on the bottle upward.
Parachute: When deployed the parachute fills with air, the parachute causes more air resistance on the way down, causing a slower decent.
Wiffle ball/disc/balloon: These 3 come together in a very essential aspect, upon release the cone is pushed downward forcing the ballon and disc to collide with the ball on the bat, after the rocket reaches its max height the force pressing on the ballon will lessen causing the balloon to push back up causing the top to come off allowing the ball and parachute to deploy.