Helicopters stay in the air using spinning blades that are used to create 'lift.' With enough of it, a craft can overcome the force of gravity, which pulls the object down toward Earth. Aircraft vehicles such as helicopters are equipped with spinning blades which are called rotary wings, unlike traditional airplanes, which have fixed wings.
A rotor wing is a lifting rotor or wing which spins to provide aerodynamic lift.
*Maple seeds are examples of rotr wings found in nature.
When the Roto-Copter falls, air pushes up against the blades, bending them up just a little. When air pushes upward on the slanted blade, some of that thrust becomes a sideways, or horizontal, push.
Why doesn't the copter simply move sideways through the air? That's because there are two blades, each getting the same push, but in opposite directions. The two opposing thrusts work together to cause the toy to spin.