I am curious now as to what the optimum speed is for this motor and the max rated capacity at that speed. Any ideas?

It sounds like direct drive might not be a bad idea after all. I will make a hub here today if I have time and toss some blades on there and see what happens. I just have in my head that it will take a lot of speed to get this thing up over 12v.  

http://www.fieldlines.com/story/2005/4/28/222819/615

I started the machining on the hub today. It is solid steel about 1.5" in diameter (I didn't really measure it, I just used something I found and cleaned it up). I machined the center out for the motor shaft. That was a pain but I got it done and it looks to spin pretty true. The clearence is quite tight so there is a nice friction fit between the motor shaft and the "hub".

I figure this will all just be an experiment, so for now this is the plan for the blades: I am going to stick with the 8' because I have some foam already a nice 4' wide. There will be a hardwood spar at the thickest part of the airfoil all the way through, then fiberglass on the outside. The hub will be the thing I machined today plus "spokes" welded in for 3 blades. All 3 spokes will be connected with a ring or straight rod at about a 6" radius to tie them all together. I want to be able to adjust the pitch of the prop in my experimentation so I am going to make a rotatable connection between each blade and the hub (with, of course, a locking mechanism so the blades don't go anywhere hehehe). I haven't quite figured that one out yet. I have a few options in my head, though.

I know wood would be "better", but this is my first turbine and I am playing around with the design. Since I have the foam insulation I am going to stick to that. Plus it is MUCH lighter hehe. From what has been said I think I will be OK with direct drive. If I can't get my ~12v+ out of it then I might work on a step drive, the gearing will depend on what my results are with the direct drive. I hope direct works, though - more time for my other class project :)

I have been researching furling set ups and I have a big question: What exactly causes the turbine to rotate out of the wind? Is it the windloading of the turbine blades rotating the off-set hub against the tail and thus out of the wind? Or is it the wind on the tail doing something to cause it to swing against gravity/angled hinge?

Is there a way to "tune" the furling so the turbine rotates when it should, not too soon and not too late? Maybe by adding or subtracting weight from the tail?

That sounds all well and good. The issue I see with this setup is I am using a motor as a generator. If the wind drops below a certain level than the system would reverse - the motor would be drivin by the batteries. That would REALLY depleat my system fast! Could I put some power diodes in there so the current only flows from the motor to the batteries?

I have also been playing around with some dump load circuitry. I will probably model the previously mentioned controller since it is already made up. I just need to find all the components.

Now the really good news. I was talking to a buddy of mine who is a Tech Ed teacher the other day when he came in. I was showing him the turbine project and he was quite impressed. His school recently bought a 5x8' CNC router/mill. He said if I could draw the blades up in CAD he will cut them out for me! I am going to use solid laminated wood, just like most of the turbines here on otherpower.com. I haven't figured out if I am going to do one at a time or take advantage of the HUGE table and do all 3 out of the same block.

I am most in-tune to Autodesk AutoCAD, so that is the program I am using. I digitized some templates I found online and used them as chord stations along the blades. The source I found had a nice layout of different blade configurations for different size turbines so I took the set of templates that was closest to my machine size (unfortunately I didn't take note of the site - I just found it and used the templates hehehe).

Now - a BIG CAD question if anyone out there can answer it. I am using AutoCAD 2005. I have 3 chord stations - root, tip, and 75%R of rotor. I am also tapering the blades from a 12" chord at the root to 6" at the tip. Nothing fancy about the dimensions - that is just what I threw together. The question: How do I form a solid through the chord stations so that the blade comes out as ONE object with a uniform flow? I don't know if there is a command I can use that will allow me to select multiple shapes to extrude to/through - sort of like extruding along a path? I tried to do a 3D skin but I can only select a beginning shape and ending shape (2), and the skin doesn't fully conform to the shape of the airfoils selected at each chord station - it flattens it out (unless that is just AutoCAD's way of utilizing less processing power?). I tried to union the two (tip to 75% and 75% to root) skins and I got a message saying that I needed to select two or more solids.

Any ideas? I will play around with it tomorrow again and see if I can figure it out. I have never tried to do this before. I have extruded along paths before, but that was a uniform cross-sectional shape. Here I am dealing with 3 shapes AND a taper...

Here are some pictures. There are some reinforcing bands I am going to weld to the spindle to reinforce the bearing caps (some thick wall tubing pressed over the ends and welded shut - like the band on a 2" reciever on a truck).