# PROPELLER FLIGHT

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.

## IN A SPIN

YOU WILL NEED

Thin paper, ruler, pencil, scissors, paper, clip.

STEP 1

Take a piece of paper, 6 x 3 ½in, and draw a T-shape on it, as shown in the picture above. With a pair of scissors, cut along the two long lines of the T.

STEP 2
Fold one side strip forwards and one backwards, as shown above, making two blades and a stalk. Attach a paper clip to the bottom. Open the blades flat.

STEP 3
Drop the spinner and watch what happens. Before dropping it again, try giving each blade a twist to make your spinner spin around even faster.

## LET'S TWIST

YOU WILL NEED

Thick card, ruler, compass, protractor, pen, scissors, 1/2in-diameter dowel, model glue, string, thread reel.

STEP 1

With the compass, draw a circle 4in across on the card. Draw a circle 1 ½in across in the center. With the protractor, draw lines across the circle, dividing it into 16 equal sections.

STEP 2
Carefully cut out the circle and along the lines to the smaller circle. Twist the blades sideways a little. Try to give each blade the same amount of twist, about 20 or 30 degrees.

STEP 3
Make a hole in the center of the cork slice with a bradawl. Put glue on the end of the dowel, and push it into the hole. Glue the cork to the middle of the propeller.

STEP 4
When the glue has dried, wind a long piece of string around the dowel. Drop the dowel into the thread reel launcher. You are now ready for a test flight.

Pull steadily on the string to move the propeller around. As the end of the string comes off, the blades produce enough thrust to lift the spinning propeller out of the launcher and into the air.

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