The water rocket is one of the most impressive simple homemade rockets. You can buy basic launchers online or make your own. An empty two liter plastic soda bottle filled with one third water, is corked, sealed and turned upside down. A needle from a foot or bicycle pump is inserted through the center of the cork while it is on the launcher, or in a bucket (facing away from you). Air is pumped into the bottle and pressurizes it. The air wants to escape. It pushes the water which in turn pops the cork. The force of the water then powers the rocket into the air. Water rockets travel fast and can reach great heights.
This experiment also uses an empty two liter plastic soda bottle and a cork. The cork is the rocket, so it looks better if you decorate it with ribbons or strips of paper. The bottle is filled with half an inch of lemon juice and some water until the liquid just under half way. A tissue, with one teaspoon of baking soda wrapped inside, is dropped into the bottle. The cork is secured and the bottle shaken. The water breaks down the tissue and the acid in the lemon juice reacts with the baking soda to create carbon dioxide gas. As the pressure builds, the cork is sent flying. This experiment can be done with vinegar and baking soda too.
An empty paper towel tube and clear film canister (with lid) are used to make this rocket. Seal one end of the cardboard tube with duct tape. Take the film canister, half fill it with water and add a quarter of an Alka Seltzer tablet. Quickly snap on the lid of the canister and place it lid first into the sealed end of the cardboard tube. Point the open end of the tube away from yourself and anyone else and watch the canister rocket out of the tube as the carbon dioxide gas inside it forces the lid off and propels the container upwards .
You'll need a two liter plastic soda bottle, two feet of PVC piping (half or three quarter inch diameter), a 12 inch piece of bicycle innertube or vacuum hose. Roll a sheet of letter-sized paper around the PVC pipe and tape the seam. Remove the paper so that you have a roll. Tape one end so that it's completely closed. This is your rocket. Connect your bottle to the innertube or hose with duct tape. Attach the PVC pipe to the tube or hose with more tape. Connect the rocket to the PVC pipe. Stomp on the bottle and watch the rocket fly into the air, propelled by air pressure.