2-Litre Water Bottle Rocket

This is a great way to reuse any two litre bottles you have lying around the house. The rocket uses solely water to give it it's upward thrust. When done properly, the rocket can achieve great heights.

Two 2-Litre bottles

Cardboard

Bicycle pump

Cork that fits snug inside the mouth of the bottle

Nail

Garbage Bag

Craft Cord

Styrofoam ball, or ping pong ball

Scissors

X-acto knife

Plasticine

For the launcher, you will need a bicycle pump, preferably not a nice expensive one, as it will get wet and the tube may suck in little bits of water, I just found a $5 one at the Dollar Store. The next thing you need is a small cork that will squeeze nicely into the mouth of the bottle. Hammer a nail into the middle of the cork, then remove it and shove the inflater pin up the small hole. I put some hot glue around it to hold it in place and help it not leak.

Now I cut out cardboard fins, these were the shape I chose, because I wanted it tall enough to be able to put the pump in from the bottom. I painted them red and added some decals after.

Next I took a marker and made a line all the way around the bottle roughly halfway up, but depending on the size of your fins, it may need to be different. I then glued the fins on using hot glue, with the top of the fin right on the line.

For the nose cone, we will take our second bottle and cut of the top. Then cut of the mouth of the top big enough to put half a ping pong ball or Styrofoam ball in. Then glue the ball in, giving it a nice rounded top. I used a permanent marker to color the ball red, matching the fins. We won't glue the cone on, as we want it to fall off at the apex of our flight, and release a parachute.

For the parachute we will use a plastic garbage bag. Trace a large circle on, and cut it out. Use the rocket for reference as to how big it should be.

Take the cap of the bottle, and fill it with Plasticine to give it weight. Then take a small Eye Bolt and screw it into the middle. This is where we will tie the cord onto for the parachutes. Then glue the cap onto the top of the bottle.

Make 4 small hole on the edge of the parachute in a cross pattern. Cut two cords a little bit longer than the width of the parachute, then feed the cords through the Eye Bolt on top of the bottle as seen in the picture above. Then tie the cord through the holes. Your parachute is now finished.

Now stuff the parachute underneath the nose cone and sit it on top. Gravity will hold it down as the rocket launches up, but inertia will take hold and the cone will keep traveling up as the rocket falls, and the parachute will unfurl. You will want someone to try and catch it out of the air, as it doesn't slow down enough to land without damaging the card board fins.

To launch the rocket, fill a large measuring cup to .8 of a litre, then mark that spot with a permanent marker, so you can just fill it up with a hose every time. Next take the bicycle pump and insert it into the mouth as far as you can. Then turn the rocket so it stands upright. It would be a good idea to use a chunk of Plasticine or something to hold the pump nozzle, so it doesn't waste water when it takes off, and you will get higher launches. Once you are sure everyone is out of the way, began pumping, depending on the amount of water and shape of bottle, it could take roughly 9-15 pumps o liftoff, be warned, anything and anyone within a good 4 foot radius will get soaked, including you. Happy flying!