Fabrication

(1)Three rectangle blades, 2-3cm in width and 13-14cm in length, are cut from the cardboard.

(2)The incision of about 1.5cm is made.

(3)Bend blades in the vertical direction as for a rectangular center.

(4)Three blades are combined by using the incision.(5)Adjust each angle 120 degrees.

(6)Three blades are fixed with the stapler.  

How to throw

Hold the boomerang vertically. Make sure that the curved surface of the blade is far side from you. Throw it forward by using your wrist.

Science

You turn to the left naturally riding on a bicycle if your weight is put on the left. The blade of the boomerang is twisted to the right. The air hits the blade and flows to the right side. The force to the left side is made.The boomerang is rotating, so upper blade air flow is fast and lower is slow.It means that the force of upper part is strong and the lower is weak. It makes same mechanism as the bicycle. The boomerang flies in circle and returns to you.