Is bigger better for windy locations?

[sunbelt57]

Here in Wyoming we have winds most days from 10 to 30mph.(4-13 m/s). Gusts can get up to 50mph. (22 m/s). I want to start collecting the parts for one of Hugh's machines. I like the 3m machine but I want to build the parts for 2 or 3 of the same kind so I can always have a backup in case 1 goes down because of lightning or high winds. (And possibly have 2 going at once). Is bigger better for high winds? Can anyone suggest a general strategy for a windy location with no trees?

[tecker]

It's all about you weight handling capability . Two 500w machines sounds good to me . If you have really strong winds at times you may want to set up a a Vawt . I don't have winds in that range and will see high winds for short periods . My ideal setup is several wind turbines at key locations with solar , batteries  and not long cable runs . Well house Workshop etc  .

[birdhouse]

sunbelt-
it seems the homebrew turbines in the 10-12 foot range are most popular.  you can go larger, but it seems the 17 footers are a lot harder to build/maintain/furl/regulate output,  not to mention the beefy tower needed to support a 17 footer. 

i run a 8.5 footer and love the power that comes out of it in my windy location!  i'd love to run a second turbine, but my tower has to be 70' to get to decently clean wind, and i really don't wanna build another one of those!

adam

[sunbelt57]

I like the 3m (10') because its the biggest one with 12 magnets & 9 coils. I figured if I could have 2 the same and make the pitch of the blades adjustable by having the root on rods going threw pillow blocks like Frans' variable pitch setup, then I could have them setup for 2 different ranges of wind speed and short out the 1 with the higher tsr when during high winds. I want to make a decision soon so I can go ahead and order the wire and magnets before the price goes up or they go out of stock.

[birdhouse]

you can get as intricate as you like, but given your windy location, i think you'll be "blown" away with how hard these machines rip out the amps even with standard carved blades! 

if i was going to stray from the piggot/dans design, the first thing i would do was go with a solid shaft, and get away from the trailer spindle.  less slop, better bearings ect. 

variable pitch is cool, but lordy, it's a lot of bits...  to break.  if i wanted to get real serious about pulling in massive power, i'd wind the stator for high voltage, and use a MPPT controller like the midnite controller to let the machine rip at whatever voltage it wants, yet the controller will decipher that into exactly what the battery wants to see. 

my machine doesn't have any fancy controller, and the power genration is through a three phase servo motor.  when the winds get going, i stand back and look at it in awe...  it's like controlled chaos with high amps! 

basically what i'm saying, is build one, keep it fairly simple, observe, and you probably won't wanna mess with all the other complexities. 

adam

[sunbelt57]

Thanks Birdhouse, I'm not talking variable pitch (just yet), I just thought it would be nice to be able to adjust the blade pitch while it was down using a wrench and then tighten it back up making sure all 3 blades had the same pitch. By solid shaft did you mean a slightly larger pipe that fits over a smaller one like the yaw bearing? At the very end of the Piggott book he talks about high voltage output and using 3 step down xformers at the battery. That would be great if all my lighting was 12v LEDs and the fridge and freezer was 12/24v. Single and double aught wire is around $4/ft. I think the big question is going to be what to do with all that extra power. I can't wait till Bob Lazar gets to producing his hydride tanks. http://www.switch2hydrogen.com/

[midwoud1]

I am rather happy with my pitch-controlled blades.
South-west and West winds can be gusty here . Seen max speed 20 m / sec.
Feather and unfeather is doing very good in combination with the microcontroller.
When the blades are feathered 20 degrees they become a bit noisy because of  stall effect.
But there is no increasing Rpm and that feels good.
It is programmable for medium and high Rpms. And full feather in storm.
Running for half a year with a few improvements.
Have to check after half a year , what need to be maintained or improved.
Builders who want to make this have to be wellknown with lathe and mill.
Still an experimental prototype .
Marijn is making a bigger pitch-controlled prop. diam. in a more professional way.
With epoxy infusion glassfiber blades and a quality actuator.
Not simple ...we like mechanisms. If it is not perfect we improve it.

Regards Frans.

[jlt]

I have built both the 8ft Piggot design And also a 12 ft .
   I like the 12ft the best. It was made with 15" rotors and all the wire I could cram into the stator.

 It puts out more than twice the power of the 8ft. And at 48v i can use smaller cables.

All the power is used through a inverter at 120 volt ac.
 The 10 ft design is basically a8ft design with longer blades.And are more subject to burn out.