Wind farms are a common sight these days, but humans have been using wind power for about 2,000 years. It wasn’t always for electricity, however, but to mill grain into flour, operate an organ, or pump water. How does a windmill do any of that though?
When you see a windmill, the part that sticks out most is also the most important: the blades. Blade designs and orientations have changed through the centuries, but they all serve the same purpose and have the same drawbacks. If a windmill has too few blades, the weight of the windmill is imbalanced and will have too much open area, catching very little wind and making it increasingly difficult to actually rotate to blades. Too many blades, and the windmill will be too heavy to easily move in the wind. In either case, power generated by the windmill suffers. Most wind turbines have three blades, and that’s the amount we see most commonly in our whirling windmills class here at AstroCamp.
Number of blades is not everything though, as you can see above; the angle of the blades plays an important role as well. Our windmill has the usual three fins, but isn’t even moving because its blades are flat against the wind. When the wind hits the blades, it just pushes them back. Once you angle the blades, the wind begins to push the blades back as well as up or down, allowing the windmill to spin. The fins must be angled consistently, however, as if blades on opposite sides are both being pushed up, they will cancel one another out and the windmill will still not move.
Adjusting the angle of the blades brought our windmill up to generating over 17 milliamps of current, though campers have gotten over 60 mA with theirs. That’s just the current generated from a tiny windmill in front of a fan, real wind turbines generate enough electricity to power thousands of homes and there are nearly 50 thousand wind turbines in the United States alone.
