During our August Workshop we lowered my 20 foot diameter wind turbine, removed the blades and put them on our neighbors new 20' machine. Scotty had some old blades off a Jacobs machine, the set was originally 23' in diameter but one had been cut down to just over 10' long so we cut the others down the same way. I'd have preferred to cut the ends off square I think, but we had to match what had been done to the first one so we did. Pictured above is the 'scrap' off one of the blades.
We fit them to the same steel hubs that my old blades were bolted into. These blades are nicely made out of laminated sitka spruce, they weigh about 35 pounds each... my old cedar ones weighed about 55 pounds each. Mine were cedar - had they been sitka spruce I expect they might have weighed more like 70 pounds each. The jake blades are very slender compared to what I had on there. They're about 8 inches wide and have very little twist or taper. We thought this would be an interesting experiment to see how they ran on my machine vs what we designed for it ~ our thinking was if they worked as well, or better... then in the future we could get by with much simpler, lighter, and less expensive blades.
Pictured above is how my machine looks now! We've been running with these blades on it for about two months now. We all know these are good blades ~ but it's a good example of 'matching the blades to the load'. On my machine, these work great in low winds. They are a bit slower to start up but performance in low winds seems every bit as good as it used to be. In higher winds however they stall miserably. To date, this fall we've had a few wind storms with winds well over 50 mph ~ in the past this machine would've been peaking at over 6kW (max peak I've seen is 9.5kW) and producing sustained output of 4-5kW. Since these went on I've not seen over 2kW ~ but again ~ in lower winds it does well and overall I don't think I'm getting a lot less energy from it. For one thing, my batteries dont know what to do with much more than 2kW coming in... so, in our windy fall season I've still had more than enough energy. The main affect here is probably just that my shop doesn't enjoy quite as much electric heat as it did in the past. Another consideration... my wind turbine is having a pretty easy life these days! I don't worry about it at all in high winds anymore. A good 'next' experiment will be to open the airgap on the alternator a fair bit and let these run faster - I expect that will make these Jake blades happier.
Last month we gave our 6th workshop at the Rocky Mountain Sustainable living fair. 12 students built a 10' diameter wind turbine in 8 hours over the course of two days. It came out nicely... we had lots of fun. DanF and I also gave a 1 hour 'intro to windpower' talk in one of the workshop tents. This is a really fun fair in Fort Collins, CO ~ it reminds me of the MREA fair, but somewhat smaller. Always fun though - interesting booths, good food, good music etc... unfortunately we usually see very little of it because were so busy!
Pictured above is a magnet rotor from a machine we built about 5 years ago with a friend. It was exactly like Matt's 15 foot wind turbine. Matt's has been surprisingly reliable but it did require some rebuilding last year (after being in the air for 4 years with no maintenance). Based on stuff that was failing on Matts we upgraded this machine by banding the magnet rotors, replacing the yaw bearing with one much larger in diameter and much longer, a more robust tail pivot and tail boom.
There is the machine finished ~ this one went to Scotties to help power his shop. It's been working well ~ he's reporting sustained output of about 1.5 kW and furling protects it past that.
Pictured above is another machine we built years ago that's just been erected. This is the 'last' of the volvo brake disk machines, I think it's perhaps 4 years old. It was built by our neighbor TomH (we have two TomH's up here) ~ it's a 10' diameter, 12 Volt turbine going on a 50' tower about half a mile from here.
Dave B sent us some blades to try out some time ago... we decided to put them on this one. They started life as a 12' diameter set, I felt bad cutting them down to 10' but TomH needed blades and I had these and have been chomping at the bit to see them fly.
We made up a nice steel hub to fit these blades. Dave will perhaps remind us what sort of wood these are made from... they are quite heavy compared to what I'm used to. Our 10' blades weigh about 4 pounds each, these are about 9. These have no twist or taper.
There it is flying! These blades definitely startup more slowly but once they come up to speed they do just fine ~ the performance actually seems very similar to what we experience with our own blades. This is also (unfortunately) a fairly turbulent site ~ I think the heavy blades have some advantage here though - it seems to keep the machine from yawing around so much in the turbulent winds. TomH lives in somewhat of a hole... in the winter time he gets about 2-3 hours of solar per day (he has 300W of PV on his roof) ~ and this turbine I expect should have a major impact on his energy situation.
Plenty going on! One nice thing - of the 14 turbines up here, there have been no problems or failures in a long time ~ and we've had plenty of strong wind.
We still have plenty of other RE projects around here to finish up this summer (darnit... I guess it's winter already) ~ two more machines to get up I hope, a couple to do maintenance on... a lot of firewood to gather! TomW's recent post about firewood has me slightly depressed...
