Bottle rockets are relatively easy to build and making them can be an enjoyable activity for kids. A simple bottle rocket requires little more than a pair of 2-liter soda bottles, some cardboard and tape. When building bottle rockets, use your creativity to experiment with different wing shapes and decorate your rocket with bright colours to make it easy to spot in the sky. Bottle rockets can be used as a learning tool to teach kids about some of the basic principles of physics.
Rinse out two empty 2-liter plastic soda bottles and remove the labels. Using a utility knife or pair of heavy duty scissors, cut the top and bottom off one of the bottles and insert the resulting plastic tube onto the bottom end of the whole bottle. Cover the seam with clear packing tape. The result will be a cylindrical extension of the bottom of the plastic bottle.
Cut three triangular fin shapes out of lightweight cardboard and attach them to the neck end of the plastic bottle using hot glue or packing tape. Space the fins out evenly by measuring the circumference of the bottle and dividing it by three, then use that measurement to place the fins.
Create a detachable nose cone to hold your rocket's parachute using heavy paper or a manila folder. The circumference of the cone should be just slightly larger than that of the bottle so it will not become stuck. Push a marble-sized piece of clay into the top of the nose cone as a weight.
Attach the nose cone to the rocket by punching a small hole in the edge of the cone itself and to the edge of the plastic extension tube on the rocket. Tie a 10-inch length of kite string to each item to connect them and knot the ends of the string tightly.
Create a parachute for your rocket out of a plastic garbage bag. Lay the garbage bag out flat and trim away the closed end then fold the bag in half horizontally. Fold the bag again, vertically this time, then fold it on the diagonal twice in a row to make a triangle shape. Measure the desired radius for your parachute from the tip of the triangle toward the base and cut the garbage bag using the desired measurement.
Unfold the parachute and discard the excess. If you folded and cut the parachute correctly you should end up with two identical circles. Lay one of the circles out flat and apply a circular reinforcement tab to the edge of the circle every few inches. Space the tabs out as evenly as possible.
Cut pieces of kite string equal in length to the diameter of the parachute and tie one end of each string through one of the reinforced circular tabs. Tie the loose ends of the strings together in a knot and attach the knot to the rocket by taping or gluing it down inside the plastic extension tube.
Fold the parachute and insert it into the extension tube then place the nose cone on top. For the best results, pack the parachute in loosely so when the weight of the nose cone causes the rocket to flip over, the parachute will automatically spill out.
Connect two 1-foot sections of 1/2-inch PVC pipe with a tee and attach an end cap to each end. Drill a hole in the centre of one end cap large enough to accommodate the stem valve from your bicycle pump. Apply some quick-dry cement to the stem and press it firmly against the inside of the end cap to seal it in place.
Screw one end of a male-thread adaptor into the base of the tee and the other end to one side of a 3-foot length of PVC pipe. Screw an elbow to the other end of the 3-foot piece and attach a 4-inch piece of PVC to the elbow.
Screw the second male-thread adaptor to the 4-inch piece of PVC then attach the 3-foot piece of PVC to the tee using the male-thread adaptor. Position the launcher so that the tee lays flat on the ground and the elbow with the attached 4-inch piece of PVC sticks straight up in the air.
Connect your bicycle pump to the stem valve and fill your bottle rocket about 1/3 full with water then screw it into the upright male-thread adaptor on the launcher.
Pump air into the bottle through the bicycle pump until the rocket shoots off the launcher. This usually happens when the pressure in the bottle reaches around 30 psi.
Decorate your rocket using permanent markers or by wrapping the outside with wrapping paper. Keep in mind that the more decorative material you add, the heavier your rocket will be come and it may not fly as well as a lighter rocket. For extra stability and friction on your rocket launcher, glue all of the connections together and wrap them with electrical tape.
Always use caution when launching bottle rockets. Keep onlookers at a safe distance from the launch pad and keep an eye on the rocket every moment it is in the air.