How to Make a Pull-String Helicopter

Measure the tongue depressors and place a mark at the center of each depressor with a pencil. Also mark two lines, one inch from the center, in both directions. Make the same marks on both sides of each depressor. Drill a hole in the center of both depressors with a 1/8-inch drill bit.

Nail three nails halfway into the wood block 1/4 inch apart in a straight line along the left edge of the block, then nail three more nails two inches apart and parallel to the first line along the right edge of the block. The nails should line up with each other.

In the first row of nails, bend the first nail away from the other two nails about 30 degrees using pliers, keeping it in line with the other nails and slightly away from the center of the wood block. Bend the other two nails 30 degrees toward the first bent nail and slightly away from center of the block. Repeat the process for the other row of nails, but bend them in the opposite direction.

Soak the tongue depressors in boiling water for 5 minutes. Put on work gloves and remove them from the water. Twist the depressors so they will fit into the slots between the bent nails. One end of the first depressor should go through the first and second nails on one side and the other end should go through the corresponding nails on the other side. The second should go through the second and third nails on both sides. Leave the depressors in the bending rig to dry.

Cut two pieces of cardboard into 3-inch squares. Fold the squares in half without creasing and shape them so that the bent end is rounded and shaped like a wing. Place a strip of electrical tape along the length of the back end of the cardboard, opposite of the rounded edge, to seal the open end. This will create an airfoil for the helicopter blades.

place the airfoils onto the tongue depressor so that the rounded ends are facing opposite sides. Slide them onto the depressor until the edge lines up with the marks you made in Step 1. Use hot glue to glue them in place. To make a spare helicopter, make two more airfoils and place them on the second depressor.

Pinch off around 5 grams of clay and press it onto the end of the tongue depressors, inside the cardboard. Repeat for the second side. Use a scale if possible, but the important thing is that there is an even amount of clay on both sides of the tongue depressors.

Cover the open end of the airfoil with three pieces of tape. Repeat for the other side.

Cut the wooden dowel to 6 inches. Line up the center mark of the tongue depressor with the flat tip of the dowel and glue them together.

Drill a hole larger than the thickness of the dowel in a block of wood and insert the dowel into the wood so the propeller rests on the block.

Wrap a string around the dowel rod on the underside of the block. Do not tie a knot, but wrap the string around itself.

Hold the block in one hand and pull the string quickly toward you to launch the helicopter.