Why are there three blades on a windmill?

Well some of you know that I was in Norman, Ok for training of the Bergey wind turbine. But I am now back and it was worth the trip to their company.

There was a lot of discussions about all the various types of turbines available on the market. Everything from vertical turbines right on up to the different turbines with one blade on up to the old fashion Aeromotors.

So because of these discussions that we had I am losing one of the turbines that I have in my line up. Let me go into more detail about why I am not going to use this particular turbine and various others.

I am going to start with the vertical axis type first, like the Windspire for example. Bergey actually tried to make this type of turbine work back in the 70's and was unsuccessful because they could not get the rpm's needed to generate power. But what they did find out that they could get torque which works great for pumping water, not good for electricity making. Also the blades are in a constant battle with each other in the wind never achieving the rpm's needed without a lot of wind speed.

Next is the one bladed machines. Which they are technically what you need to make a wind turbine generate a lot of power. But they are so lop sided that there is to much to go wrong. The other thing is you need a lot of wind to get it started. But once that happens it spins very fast and that's where things go wrong.

Two bladed machines are the next better choice. Again they are plagued with their technical problems. The problem with them is the blades get teetering back and forth causing alot of strain on the blades and the hub bearing. As the blade passes the tower it causes the blade to unload the wind blowing against it. Because the wind has to move around the tower. So the bottom has less force and the top blade has all the wind's force causing this teetering effect on the blades.

Three bladed is what turbine manufactures use because it is reliable and it helps get rid of some the other issues that other turbines with other blade configurations have. It is easier to balance the load on the hub with three blades. Like the two bladed turbines the three bladed turbines can counter act the teetering effect much better. Because there are always two blades in the wind. With the turbine being horizontal all the blades are in the wind at any given time not like the verticals which are not.

Now on to the reasoning of why I have decided to drop one of the turbines that I currently have. It's because it is a multi-bladed turbine. Since it has more then three blades the turbine will actually slow down, producing less power but more torque. Just like the Aeromotors in the old pictures of farms with windmills that you see with a lot of blades. Those turbines were designed for more torque in less winds to pump water out of the ground. Not for speed to generate electricity like we are today with the new wind turbines.

You may say just because I went to Bergey and they talked about these different blade styles. How are they correct? Well here is my take on that, they have been around thirty years and they are one of the very few left from the energy crisis back in the 70's. So to me that gives them a lot of credibility in my eyes. There are a lot of companies today that are trying to get rich quick and I'm not one of them. I believe you get what you pay for.

My mission is, "To seek out the best turbine, producing the most power, that can be reliable, and at is most reasonably price possible."

Stop back in the next few days and I will have more to say about my trip to Norman, OK and the Bergey product. I will also be talking about the turbine that is replacing the Skystream and Raum wind turbine too.