17 ft machine furling

[Wind Doc]

I have just put up a 17 foot machine to replace the 10 foot one I've had for a couple of years. I followed the Homebrew Wind Power plans for the 17 foot machine pretty close. I did increase the offset as per Dan's recommendations. It is 17' swept, 10" offset, 8.5' tail boom with fairly light 1/4" birch plywood at 12.5 square ft. It is only putting out 1250 watts before it furls. I have 1 1/16" air gap with a cut in speed of 80 RPM. My question is should I add more weight to the existing tail, or extent the length of the tail? How much weight or length would be needed? The plans indicate this should be a 3-4 KW machine. Another question is how much power can I produce before causing damage to the stator? 2 strands of 14ga 59 turns bedded in Vinyl Ester.

[kitestrings]

Nice!  Congrat's.

Give us some more details and pics if you have them.  The gap sounds large to me, but others working in this size can advice better..

thanks for sharing, ~ks

[Wind Doc]

With a 1" gap my cut in speed was 76 RPM so I widened it to achieve a cut in of 80 RMP (as per plans). 48 volt system 200 amp/hr storage with a 6kw Xantrex feeding a sub panel in my house. I really like the functionality of the Xantrex as it seems to handle the turbine output variations very well.

[jarrod9155]

I am not that furmiliar with the design of your 17 footer but I would think that 1250 watts isn't bad , but your missing a piece to answer your question what was the wind speed when it furls . Just making a a guess with your power output 20 mph wind speed .if your furling at above 25 mph and only seeing 1250 watts try tightning up your air gap up alittle .  My 18 footer I had would push 1800 to 2100 watts before furling at 25 mph winds . Hope this helps

[Dave B]

I have some advice, take it for what it's worth. Let your machine run and observe it for quite some time in all conditions before deciding if you want to make any changes. Turbulent, gusty winds will not give you a good idea of your furling and output performance. Straight line, constant wind varying in windspeed and being able to monitor this speed accurately while observing your machines performance and furling etc. is the only confident way to base your decisions on any design changes. I have made the mistake, a flopping around partially furling tail does not necessarily mean early furling. If you have not observed the straight on consistant winds of 25-35+ MPH I would be very hesitant to make any changes before hand. If your 1200 watts is some where around 20 MPH you may be much closer to being on the max edge than you think, above 20 MPH things happen very, very fast and tweaking your furling very little can push you over 3 KW in a big hurry. Enjoy a conservative machine instead of as Chris would say a "buzz bomb" high speed machine always waiting to blow. Stay safe,  Dave B.

[Watt]

I have just put up a 17 foot machine to replace the 10 foot one I've had for a couple of years. I followed the Homebrew Wind Power plans for the 17 foot machine pretty close. I did increase the offset as per Dan's recommendations. It is 17' swept, 10" offset, 8.5' tail boom with fairly light 1/4" birch plywood at 12.5 square ft. It is only putting out 1250 watts before it furls. I have 1 1/16" air gap with a cut in speed of 80 RPM. My question is should I add more weight to the existing tail, or extent the length of the tail? How much weight or length would be needed? The plans indicate this should be a 3-4 KW machine. Another question is how much power can I produce before causing damage to the stator? 2 strands of 14ga 59 turns bedded in Vinyl Ester.

Congrats on your build.

Just curious what size wire you have down your tower and to your battery bank?

[Wind Doc]

90' of #6 Cu down the pole, 120' of 2/0 Al to the garage, and 10' 2/0 Cu to the batteries.
In answer to the previous question I was recording 16 to 20 MPH of wind while watching the furling. It wasn't a good steady wind, but gusty. This Scenario  is much better than a machine that runs too fast, or won't furl due to wind seeking characteristics! I experienced this when I put my first 10 footer up a couple of years ago.
Thanks for the comments!