## Thursday, 26 September 2013

### Science: Make a propeller!

We made this fun toy today for our latest practical science project.  It makes for another great homemade toy.

So if you want to make one yourself, here's how to do it...
You will need:
• Stiff cardboard (cereal box cardboard will do)
• Scissors
• Ruler
• Glue
• A compass
• Pencil
• A slice of cork (from an old wine bottle will do)
• 7.5cm length of 3mm-diameter dowelling, modelling glue,
• String or strong cotton thread like the ones used for sewing on buttons,
• A cotton reel
STEP ONE
Using a compass draw a circle onto your card that has a 5cm radius and cut it out carefully

STEP TWO
Draw 2 lines through the circle to find the centre and then draw another circle in the middle that has a 2cm radius like this...

STEP THREE
Divide the circle into 12 equal pieces like this...

STEP FOUR
Carefully cut along the lines to the smaller circle.  These flappy bits will be your blades.  Give each blade the same amount of twist, about 20 to 30 degrees.

STEP FIVE

With your bradawl make a hole in the centre of your slice of cork and then take you piece of doweling put a piece of glue on the end and stick, the glued end, into the hole in the cork.  Then glue the cork to the middle of the propeller.

STEP SIX
When the glue has dried, wind a 50cm long piece of string around the dowelling.

STEP SEVEN
Drop the dowelling into the cotton reel launcher and then you are ready to test it out!

Pull steadily on the string to whirl the propeller around.

HOW DOES IT WORK?
When you pull the string the propeller turns and as the end of the string comes away, the blades produce enough thrust to lift the spinning propeller our of the launcher and into the air!

This makes for a great toy for children and adults alike.  It also makes for a super fun science lesson!

What else are we learning?
Maths:
Measuring, dividing
Design and Technology