Testing aerofoils.
Aerofoils are structures that push upwards or press downwards by changing the speed of the air passing around them, like the wings of aircraft, or may cause movement in a particular direction, like the sails on a yacht. In this experiment you can put different things to the test to see which of them make the best aerofoils.
You will need:
- Rulers of different shapes and made out of different materials – It is important that they should be very light.
- Rubber bands or adhesive tape
- A small electric motor... we are going to use a cappuccino frother, but you can use any small electric motor even one from a broken toy car.
- Very accurate scales like digital kitchen scales
- A small amount of modelling clay
And last but not least ... a helping hand from an adult.
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Method
First of all place the kitchen scales on a flat level surface away from draught.
Then fix a ruler to the electric motor using some rubber bands.
Be careful to fix the ruler well to the motor, and that it cannot slip when the motor is running.
When the ruler is attached to the motor, fix the motor on top of the kitchen scales.
Stabilise it by surrounding it with some modelling clay and switch on the scales. Note the weight of the ruler and motor. Start the motor.
When the motor starts running, the ruler starts turning, and wind passes over it.
When the reading on the scale settles take another reading of the weight and subtract it from the first reading.
Turn the ruler around so that if the rounded side was facing upwards, it now faces downwards and run the test again and compare results.
A good aerofoil will change the direction of the air so that it rises or presses down.
So the better aerofoil would be the one which either increases or decreases the weight of the electric motor the most, according to how it is attached.