Pop pop boats are toy water crafts, powered by a simple heat engine. The source of the boat's power can be a small candle, heating the engine and boiling the water in it. The expanding steam pushes water in the engine's tubes and when it condenses, it creates a vacuum that draws water back in the engine. This repeated process moves the craft forward, producing a characteristic "pop pop" sound. Making the boat's hull is not a difficult task, but the most challenging step is making a functioning. heat engine.
Making the Engine
Cut out the top and bottom of the soda tin can. Carefully expand the remaining parts of the can on a flat surface, to get an aluminum rectangle.
Fold the aluminum rectangle in half. Print the boiler pattern from Science Toy Maker (See Resources) and use sticky tape "donuts" to tape it on the folded aluminum. Cut out the edges of the paper pattern that stick out of the aluminum.
Cut out the parts of the aluminum that fall outside the pattern's solid lines. Fold the aluminum on the dash lines of the pattern, pressing hard on the folded lines, to create two "trims." Remove the paper pattern and the sticky tape "donuts."
Open the "pocket" of the aluminum with your thumbnail. This is the open end of the structure, created when you first folded the aluminum rectangle.
Insert three drinking straws on the pocket carefully. The goal is to create one arched side on the aluminum structure, while the other side remains flat. Push the drinking straws gently inside the pocket until you feel they cannot penetrate the structure anymore.
Remove the straws and carefully apply epoxy between the two layers of aluminum of the folded trims. This way, you can seal the air and water within the engine.
Use a ruler to measure 1/4 inch on the short side of two bendy straws. Cut out the excess length and place the short side inside the engine's pocket. The bendable part of the straws must be on the edge of the pocket.
Apply epoxy on the open parts of the pocket to seal it. Put some water inside the straws and shake the aluminum structure to complete the engine.
Making the Hull
Form any type of boat you want out of a milk carton. This material is water proof, easy to glue and easy to paint. You can also download the template from Science Toy Maker (See Resources).
Place a small candle, standing upright on a piece of tin foil, on the front part of the boat's "floor." The tin foil must be glued on the floor. Open a hole for the drinking straws, 1 inch in front of the candle.
Place the engine above the candle, so that it forms a 45-degree angle with the floor. The drinking straws must go through the hole. Use sticky tape to ensure the drinking straws are parallel to the ship's bottom.
Light up the candle, place the boat on water and wait until the engine starts working. The boat will move around the surface, making a distinctive "pop pop" sound.