Windmill update

[imsmooth]

I watched to see my wind turbine perform.  25-45mph winds.  I don't have the inverter, but I do have the shunt controller and dump load.

The turbine furled at about 25mph - I was going to adjust that to 35.

The dump load and shunt controller worked perfectly, kicking in as the rpm got too high, dumping 1000w as needed.  The blades spun well and the tower held.  The emergency brake, which I then engaged, worked flawlessly.

I left home and came back and something didn't look right.  I had left the wind brake engaged.  When I looked up the blades were still locked down, but the tail was gone.  The metal tubing had snapped.  Since it was held in two places, one must have snapped and then it must have bounced like a flag, chopping the tips of my blades off.

Now I am without blades and tail.

I plant to carve them again, but would like to try something less expensive than cedar.  Any suggestions?  Fur, pine?  I am going to coat them with epoxy so the weather should not be an issue.

If you go to http://www.mindchallenger.com/wind  you can see what it did look like.  Maybe I can get some suggestions for strengthening the tail.

[ghurd]

If the brake was working, how did the tail get all the blade tips?

Bummer.

G-

[imsmooth]

I pieced it together.  The tail was swinging wildly in the wind and snapped where the pipe was threaded.  The flailing tail cut the brake cable allowing the blades to spin.  Once spinning the tail flew back and snapped the tips and fell off.

[bob golding]

been there done that. made the tail too long. all part of the steep learning curve i am afraid. as regards the blade material, i use 6x2 construction pine. the sort they use for roof trusses. has held up well for the last 3 years. i just paint it with 3 coats of normal household paint. i wouldn't use epoxy. normal household paint breathes and lets the moisture out. epoxy wont do this and the wood gets waterlogged in the same way as a fibreglass top on a wooden boat does.

cheers

bob golding

[pmurf1]

 What happened to the TLG blades that were on there and why did you get rid of them?Which model were they? Were they worse, better, or equal to the ones you carved? Would they have survived what happened to the wood ones? Just curious, I have a set of boast busters on mine and like them.

[Flux]

Don't use pipe threads in any windmill construction many towers have failed because of threaded couplings and even for tail construction it is a very weak point. The Otherpower type tail looks a very highly stressed thing anyway and needs solid construction and good welding.

Flux

[imsmooth]

Yeah.  The welds all held, but the threads didn't.  The next one won't fail at the tail...

[imsmooth]

The TLG blades worked well, but were too small for my generator.  They were 8.5'.  I had to carve blades to make a 10.5' rotor to have enough wind energy.  My generator, in fact, can probably take a 12' rotor, but this is too large for my tower.  I think my blades worked better.  They were totally silent up until about 300 rpm when I could here the wind rushing by them.  The TLG blades also had some soft wind noise.  The start up was the same as I designed mine with a wide, deep root (10" wide, 2.5" deep).

Nothing would have survive the hit.  Instead of flying wood it would have been flying metal.  The tail boom is metal and it would have sliced the aluminum blade tips.

[imsmooth]

Flux,since I have to redesign my tail, do you have any pictures of a better one?

[oztules]

yikes....

If you still have your blade jigs set up, at least you can have a new set of roughed out  blades built in a few hours....

........oztules

[ghurd]

I have been thinking about this, and I can't swallow it.

I do not know much about furling.

Someone correct me.

If the blades were locked down tight, the tail would not be flailing wildly.

It would have a hard time furling at all?

Was that tail assembly made of 1/2" gas pipe?

I am guessing the repeated yaw stress broke it.

The lower photo here looks like the tail support is bending from the tail weight,

http://www.mindchallenger.com/wind/wgpage9.html

A 10.5' blade set will cause a lot of yaw stress.

If I was piecing it together, it would fall on the undersized tail supports, or the mechanical brake failing (before the cable was cut).

Again, Someone correct me.

G-

[imsmooth]

Yes, 1/2" gas pipe.  I actually saw the tail furling during the gusts even though the blades were locked.  The boom was bumping into the brake cable.  I guess I didn't have enough clearance to account for dynamic stresses as there was enough clearance under static conditions.