Making an Air-Screw
You will need: Stiff drawing paper or thin card, ruler, pencil, scissors, compass, cork, needle.
Warm air always rises. With a constant source of heat, we can use a current of warm air to turn a miniature turbine or 'air-screw.'
Take the drawing paper or card, set the compass to 2 inches and draw a circle on it. Reset the compass to half an inch and draw a smaller circle inside the larger.
Carefully cut around the larger circle and then rule 16 or 18 lines across the paper disc, in the manner shown in the diagram.
Cut along these radiating lines but stop each cut at the edge of the inner circle.
To create the turbine-wheel you must give each blade a slight twist, each in the same direction. When the blades have been carefully set in this fashion, insert the blunt end of a needle into the end of a cork and balance the 'air-screw' on the point of the needle.
Make sure that the little turbine turns easily
on its needle mounting. Now place the completed instrument above a source of
heat, such as a radiator or even a lighted lamp. As the warm air rises, it will
come in contact with the blades of the air-screw and set the wheel spinning.
The greater the heat the faster the wheel will spin.
Copyright © 2018-2020 BrainKart.com; All Rights Reserved. Developed by Therithal info, Chennai.