Propellers work in two different ways. When a propeller spins, it makes air move past it. Propeller-driven aircraft use this effect to produce thrust. Moving air also causes the propeller to spin. The projects here look at propellers working in these two ways. In the first one, you can make a simple paper propeller called a spinner. As the spinner falls, moving air rushes past the blades, making it revolve. This acts just like the fruits and seeds of maple and sycamore trees, which have twin propeller blades. As they drop from the tree, they spin and catch the wind, and are carried far away.
In the second project, you can make a spinning propeller fly upwards through the air. The propellerlike blades are set at an angle, like the blades of a fan. They whirl around and make air move. The moving air produces thrust and lifts the propeller upward. Children first flew propellers like these 600years ago in China.
Thin paper, ruler, pencil, scissors, paper, clip.
Thick card, ruler, compass, protractor, pen, scissors, 1/2in-diameter dowel, model glue, string, thread reel.