What better way can there be to introduce children to science than by building a bottle rocket? Materials that can be obtained from any kitchen or garage can be assembled within a matter of moments to demonstrate the principles of pressure and propulsion.
It’s easy to learn how to build a bottle rocket. You’ll need to cut off the top and bottom of a 2-liter soda bottle to obtain a cylindrical tube. This cylinder is taped to a second 2-liter soda bottle in order to form the fuselage that stores the parachute.
Three triangular fins have to be cut out from a manila folder. Be sure to include flaps on the fins so that they can be taped to the bottle at equal distances on the uncut soda bottle. Straight lines can be drawn on the bottle as a guide. For more precise fin placement, measure the circumference of the bottle and divide it into 3 to determine the exact distance that should exist between the fins.
The nosecone on the fuselage is made from an athletic cone. The bottom tip of the cone has to be cut off. A ping pong or golf ball-sized piece of clay can be packed into the nose of the cone to give the bottle rocket more momentum. The cone itself should be symmetrical and slightly wider than the bottle’s diameter.
You are nearly halfway through the process of how to build a bottle rocket. The cone is attached to the fuselage with string anchored with duct tape at either end to the inside fuselage and the cone. If you face trouble keeping the cone on the fuselage, you can make a platform with 3 small fins, taping them near the top of the fuselage where the cone should sit.
For the parachute, cut the closed end of a garbage bag off so it’s open at both ends. Fold it in half along the shorter side of the bag, making sure the edges match before folding it in half again along the longer axis. Fold the bag again so that it forms a triangle, with its base being the end that was closed in the previous fold. Cut away the rectangular section, leaving just the triangle. You should have two canopies when you unfold the bag.
Fold one canopy in half, and fold twice more, creasing the folds each time. When you unfold it again, it will have been divided into 16 sections. Mark the edge of each crease with tape or reinforcement tabs. Holes are punched through the masking tape or reinforcement tabs so that the kite string can be attached to form the parachute. Fold the canopy in half again, tying the string through any 4 of the holes before tying the strings together at their most distant point from the canopy. Repeat 3 times to complete the parachute. The chute can be attached to the fuselage with duct tape before it is loosely packed and the nosecone put back on.