The Physics in Pulled String Flyer Toys

Gravity

• The first and most fundamental force that acts against anything is gravity. This force is taken for granted as people encounter it every day. Just like when jumping, when flying an object, the first force to pull it to the ground is gravity. Nearly every aspect of the design of pull-string toys works to counteract the force of gravity and, for at least a few seconds, pull string toys have the ability to overcome this force.

Newton's Law of Rotation

• Not only do pull string toys appear to defy gravity, but they also seem to fly with precision, balance and elegance. The balance of the toy while in the air can mostly be explained through Newton's Laws of Rotation, which focuses on the acceleration and force of the rotation of an object. These rotational forces counteract gravity and provide stability as long as the object rotates at a high enough speed. A simple top provides an excellent example of Newton's Law of Rotation.

Helicopters

• One similar object to the pull string toy is a helicopter, which operates on similar principles. They commonly have propellers which, on both objects, take air from above and push it to the area below. For the toy to fly upward, it must have a thrust that counters its own weight, much like a helicopter. When the thrust is above that of the weight or opposite force, the object proceeds higher; when the force is less, the object succumbs to the forces of gravity.

Pull String

• The source of the thrust comes from the string. Although strings on pull-string toys are attached in different ways, usually they are wound around a cylindrical object. The winding allows extra length for the string which serves to magnify the force of the pull. The kinetic energy from the string rotates the cylindrical launcher (where the flying propeller is held). When enough force spins the propeller like a top, it rises because of the thrust and transfer of air. As the energy dispels, it ultimately slows and falls back to earth.