Aluminum blade trouble

[Saidrich]

Well, I have proved that my windmill will exceed 15 watts: For a short time, in 75 mph winds.

After a few hours of this gusty wind, one of the blades flexed and hit the post.

This is what happened to the way-ward blade.

A little closer look.

My DC fan was spinning so fast it started to move across the shelf and the voltage meter attached to the wind mill is shot; lesson learned? Don't use aluminum blades... unless you want to damage your windmill tower.

[powerbuoy]

I read your comments on aluminum blades. I know that there is a number of people sharing your concerns. However, I cannot agree to the statement "do not use aluminum blades". Aluminum comes in many shades or forms. Depending on the type, you'll receive a very rigid, lightweight and easy to machine material. Sure, people talk about bending fatigue and stresses. They see one broken prop and demonise aluminum immediately. I can tell you though that there are probably some examples out there that will show broken fiberglass blades or other materials as well. If you want a windy example where aluminum has survived for decades look at the aircraft industry. Small props are made of aluminum. They constantly survive changing speeds, wind forces and haul a big butt airplane behind them. I trust that your design would have held up better if the aluminum material would have been either thicker, a different alloy, or if it would have had a stiffer shaping. However, everybody who puts up a tower and tries things out has my full respect. Hope you do not take my comment the wrong way.

Powerbuoy

[Saidrich]

I have to agree with you powerbouy, WXYZCIENCE his brother and I all have this type of blade and have been watching them for about 3 years. The blades are made of aircraft aluminum. With a little work this windmill will be back up on my roof.

My neighbor told me that the first thing he does in the morning is look at my windmill to see what the weather is like. Thanks for commenting and coming over to our side.

[nanotech]

Just the fact that it was able to be up there in a 75mph wind is a testament to its strength!!  I seriously doubt anything I could build out of wood would last HALF as long!!  

[wpowokal]

If you could increase the diamiter of the disc they are mounter on I suspect they would be fine, or double thickness for the first few inches.

allan down under

[powerbuoy]

hope its not the dark side ... :-)))