How to Make a Water Bottle Rocket

Constructing a Water Bottle Rocket

Gather the supplies. For this rocket, you will need one water bottle, one pen, one foam football, duct tape or hot glue, and cardboard. You can really use any type of water or soda bottle. For a larger rocket use a two-liter soda bottle.

Prepare the water bottle. Remove label (if applicable) and discard. Take the cap off, but save it. You will need it later. At this point, you may want to consider decorations like paint, stickers, colored duct tape and the like. (You can decorate later, but it may be easiest at this stage).

Take apart a disposable pen. Bic Pens work great. Remove all parts and set them aside. Use caution when handling these components of the pen. It is easy for the ink cartridge to explode.

Saw the pen's barrel in half. Don't try this with the clear plastic pens because they will typically crumble. The white plastic cased pens work the best. If you don't have a saw or find it dangerous, you could use a kitchen knife.

Prepare the cap. Take the cap of your bottle and outline the size of the pen barrel onto the cap. Hold the halved pen barrel and trace it with the pen cartridge.

Cut out the outline. Take a drill the size of the pen barrel and drill into the center of the cap. You could also try to use a knife if you don't have an accessible power drill.

Create fins out of cardboard. Take a piece of cardboard or similar material and cut out 3-6 large fins. You will want these to be fairly large because they will hold and support the rocket before take-off. Look online at rockets for inspiration.

Attach your components. You can either use duct tape or use a hot glue gun. Do not use "Crazy Glue" or similar adhesive, as it will chemically dissolve the plastic. Evenly attach the fins so that they are facing down from the water bottle's cap. Treat the fins like feet for the rocket. The rocket's tip, or the bottom of the water bottle, should be facing the sky. If the fins are uneven, the rocket will not shoot straight into the air. It may veer off course. Typically, the goal is to fly high, not sideways.

Connect the pen. Take the pen barrel and insert it into the hole of the cap. If there are any gaps you should seal it with used gum or another malleable adhesive.

Launching the Water Bottle Rocket

Find a safe launching area. Water bottle rockets need unobstructed space for safety. Therefore, you need an area safe from people, animals, and objects that could be injured by a plastic bottle hurtling through the air. Bottles may end up in trees or roofs of buildings, too. Places like athletic fields, parks with limited numbers of people, and empty parking lots are preferred.

Add water into the bottle. Fill the bottle so that the water is about 1/3rd of the way full. The action occurs when the water mixes with the compressed air.

Attach to a bike pump. This is where you will be able to see if you constructed the cap correctly. If you attach the pen to the bike pump and it doesn't leak when put upside down, it's ready to for your countdown. If you are struggling with this step, you could secure the pump using tape or some gum. It'll still propel into the sky, and may even go higher if something is resisting its flight.

Position your rocket. Don't be a jerk and point at somebody. Also, it's a good idea to steer clear of any neighboring windows. If your fins are secure and well portioned, the rocket should upwards.

Pump air into the bottle. You are creating a fuel by each pump you send to rocket. It can't fly with only a few pumps. Continue pumping air into the rocket until it takes off. Be sure any kids or friends aren't too close while you pump. The water will gurgle after each pump.

Use an alternative system. Instead of using the pen cartridge in the plastic cap, you could just use the bike pump. Remove the cap. Wrap the bike pump with tape or until it seems like it will be a tight fit into the mouth of the bottle. Stick the pump directly into the water bottle. If you did this correctly, you should have to really work for the bike pump's hose to fit into the bottle.

Using Baking Soda and Vinegar

Find a bottle of water. It doesn't matter what brand you use. Just be sure that it is fully emptied. Don't waste the water for this experiment. Give the water to some plants if you're not thirsty.

Gather baking soda and vinegar. Most households carry these two products, but you can also purchase some if you can't find any. For the vinegar, it's best to use the cheap, white distilled vinegar.

Combine your ingredients. Use about two tablespoons of vinegar and baking soda. Mix the two ingredients in the bottle. These products will immediately react from coming into contact with one another. This chemical reaction is the fuel for the rocket.

Secure the lid. You'll need to be quick when you cap the water bottle. Careful not to let any of the combinations out when you're sealing the lid on. The plastic water bottle will start to expand once capped. This will create the necessary tension required for the rocket to fly. For greater tension, shake your bottle up. Don't over-shake the bottle because it could explode in your hand. Make sure that people around you are keeping their distance from the water bottle. This method creates more of an explosion based rocket, so it can be a little dangerous.

Throw your "rocket." This can be a dangerous step if you haven't taken the proper safety steps. Make sure everyone you are with is not standing nearby. Throw it onto cement and aim for the plastic lid. The plastic lid should explode from the impact causing your rocket to shoot into the sky. This is not the most secure way of creating a rocket, but the effect is similar to the other approach of creating a bottle rocket. This is an easier technique that needs to be treated with more precautions. Safety first!