This is an instructable on how to make a water rocket using only recyclable materials. All materials can be found in your house or classroom. This also involves a parachute, which is attached to a tennis ball, that will be deployed and in the air for at least 30 seconds. It's simple and quick, all you need is the right materials.

Materials:
2 2L Bottles
1 Thin Garbage Bag
1 Manila Folder
2 Sheets of Arts & Crafts Foam
1 Water Balloon
3 Rubber Bands
1 Tennis Ball
Fishing Line
Scissors
Exacto Knife
Duct Tape
Masking Tape
Stapler/Staples
Wire

Step 1: Cut the First Bottle

In this step you will have to use an Exacto knife to cut out the center of the first bottle. Look at picture to see where to cut. Make sure you keep the top and bottom leftover from cutting out the center.

Step 2: Attach the Bottles

Place the middle of the cut bottle on the bottom of the second bottle and attach using duct tape. Make sure the two pieces are securely attached.

Step 3: Adding the Fins

Take the manila folder. Along the folded side, cut three triangles so when they are opened, they appear as diamonds. Fold the edges of the fins so there is a flat piece that will be taped down to the bottle. Attach the fins to the bottle using duct tape.

Step 4: Creating the Top

Creating the top of your rocket is really simple. All you have to do is take the top of the first bottle you cut and attach it to a foam cylinder using duct tape. Then take a piece of foam and place it under the top of the bottle. Trace the outside of the circle on the foam. Cut out the circle with the Exacto knife. Use the outside as a skirt and place it around the cylinder, attach using a stapler.

Step 5: Inserting the Elastics

After creating the top, create 6 incisions using the Exacto knife, spread equally apart, around the top part of the cone. Then cut each elastic band so they are straight lines. Slide the rubber bands through the incisions. The first one through the first incision, and through the incision across from it; the second one through the second incision, and through the incision across from that; the third through the third incision, and through the incision across from that.

Pull both sides of the elastics up over the top of the bottle and screw on the top to hold in place.

An asterisk should appear in the inside of the top of your cone.

Step 6: Creating the Parachute

Take your garbage bag and cut the bottom off so that it lays out flat into a big rectangle. Then cut down the center so you have two squares. Cut a circle out of one of your squares, and there you have your parachute.

Step 7: Attaching the Tennis Ball

Using your Exacto knife, cut a hole through the tennis ball. Take a piece of wire and loop it through the tennis ball so it creates a handle. Then take your parachute and put 8 pieces of masking tape, spread evenly around the edge. Then punch 8 holes, one in each piece of masking tape. Take your fishing line and cut 8 even pieces. Tie one end of the fishing line to a hole in the parachute and the other end to the handle on the tennis ball. Repeat 7 times. Make sure the fishing line is taut when you lift up the tennis ball in the center of the chute.

Step 8: The Balloon

The ballon should be blown up to capacity (which isn't very big because it's a water balloon). After it is blown up, place it in the top of the cone.

Step 9: Folding the Parachute

Fold the parachute in half horizontally and then again vertically. Fold the parachute into vertical triangles. After it is the thinnest you can make it, fold it in half horizontally. Place the tennis ball, followed by the parachute in the bottom of the bottle rocket.

Step 10: Launching

Fill your bottle between 1/2 way & 2/3. Pump the air pump to between 60 & 80 and launch! The air pressure on the top, to the balloon should bounce the top off on the way down, releasing the top and then your parachute. Watch as your tennis ball floats through the air!