©2014 FIRECRACKER™GUW ALL RIGHTS RESERVED

Windmill propellers

(Click to enlarge photo)

This is a home-made steel propeller where the 'twists' have been carefully made to match the velocity of the wind along the propeller's length. The bolt and nuts just out from the middle on one side are for balancing, on the opposite side there is a magnet for the tachometer sensor so the speed can be logged. I am not particularly interested in the specific aerodynamics for this propeller although, I do want it to be as good as it can be for the price, my main concerns are ease of fabrication, cost and power output at a given wind-speed.

Mounting is by means of a taper-lock system which is solid and works well. The sprocket cogs are of no significance it was just the cheapest way to get a taper-lock body made of mild steel for welding. The sprocket was tricky to weld around the teeth but, no doubt, a better idea will emerge in time.

The diameter is my standard 1.2m (4 feet). I like this size because it is a good compromise between a reasonable amount of power output versus the problems with stress at a larger diameter. Note that the blades do not go all the way to the centre, this is to make construction easier and a small sacrifice because that swept area contributes very little towards overall power.