A bottle rocket is a simple experiment involving increased air pressure and the inevitable release of that pressure, causing the bottle to launch into the air. A bottle rocket launcher can be constructed with a few simple supplies.
Put together the stopper. Take the 3/8-inch drill bit and widen the hole in the stopper. Put the snap-in tire valve into place with the threading on the wide side of the plug.
Attach the mounting plate to the wood base. Use the mounting plate to mark and drill holes into the wood base with the ¼-inch drill bit. Using the 3/8-inch drill bit, drill a hole in the middle of the metal mounting plate for the stopper to attach to. Push the carriage bolts up through the bottom of the wood base, and secure them to the base with a washer and tightened hex nut. Affix another hex nut and then a washer to each carriage bolt, approximately half of the way down. Place the mounting plate onto the carriage bolts, and then lock it into place with a washer and hex nut, tightening with the pliers. Work the stopper through the middle hole with the tire threading facing down.
Attach the corner irons to the base. Affix the 2-liter bottle so that it is resting on the rubber stopper. Taking two of the corner irons, position them so that they are like bookends facing one another and slide a 6-inch spike leading through the top hole of one to the other. Position the spike perpendicular to the mounting plate so that the spike is directly next to the neck of the 2-liter bottle and directly over the protruding lip of the bottle. Screw this into the base using three wood screws on each corner iron. Repeat the process with the other two corner irons with the spike touching the opposite side of the neck of the bottle and screwed into the base, as well.
Attach the pull cord. Several inches out from the corner irons attach the eye bolt by drilling a hole through the wood base, and attaching the eye bolt via a nut and bolt on either side of the base to secure it down. Tie a 6-inch piece of the cord onto each spike. With the rest of the cord, tie it onto the middle of the cord attached to the spikes. Lead the cord through the eye bolt.
Drill a hole for stabilisation. In one of the corners opposite the pull cord, drill a hole in which to affix one of the tent stakes through. While in operation, this will stabilise the base into the ground for when the pull cord is yanked.
Prepare for launch. Attach the tire pump to the threading on the stopper. Fill the 2-liter bottle about a quarter of the way full with water and quickly flip it upside down into place on the stopper. Slide the spikes into place to hold the bottle down. Pump it up with the tire pump until it has about 22.7 Kilogram of pressure, careful to be at a safe distance away, and then yank the cord.