6 inch dia. Zubwoofers

[bug bit]

I ended up with a 4 foot long section of 6 inch thick wall pvc tube ( .300" wall thickness above/below ground ). Using Zubblys program to get sizes, I cut out a really nice looking prop. It balanced great and didn't warp a bit. When I mounted it up and turned it into a 20-25mph wind blowing right off the lake, it just sat there. even when I grabbed it tnd spun it, it would stop. All I can figure is the tube is too thick? I have a 3 foot blade made out of 3 inch pvc that goes to a blurr when there is just a little breeze. Any thoughts on what I did wrong here?

[henjulfox]

A picture might help.

Only way I can think of that a 4' blade wouldn't turn in a 20 mph wind would be if

you accidently cut it so that the pitch of the 2 sides are opposing each other - one

half is cut to turn clockwise and the other half cut to turn counterclockwise.

-Henry

[georgeodjungle]

or

is it mounted the same as the 3' x 3"?

to big of a motor or generator will do it, with a to small of a prop.

kills low speed start up.

[bug bit]

both have been mounted on a small cooler motor i put magnets to. 4 coils, 4 magnets and very litte resistance. the small blade spins like heck, i figured the bigger blade would do the same.

[wooferhound]

 6 inches is pretty small to catch the wind. You should also round the leading edges and sharpen the trailing edges on a prop this small. you would also probably need some pretty strong angles too, maybe a hub angle of 45 degrees and a tip angle of 22 degrees.

[ghurd]

Seems some guys are mixing pipe dia and blade dia.

I'm no expert.

If they are anything like the ones I played with,

The 4' of 6" blades should start easier than the 3' of 3".

I would not expect the thickness to be a very bad thing.

Even the ones I really mangled started OK.

My worst ones started to show problems at maybe 60RPMs.

The only thing I can think of is a problem with the gennie end.

Maybe the extra weight on the bearings? Or bending the shaft to bind the bearings?

Maybe a short in the gennie?

Is there a output load with the 4' that was not there with the 3', like a light bulb to act as a brake?

Maybe lay it flat, blade facing the sky and see if it spins free,

then try blade facing the ground.

Maybe take it in a quiet house and listen for grinding or other evil noises as it turns.

Let us know,

G-