This is the second test of the super low cost (NZ$30), easy to construct (6 hours for two people) build of the Lenz2 vertical axis design, with the intention being of surviving sustained 100 km/h winds. I didn't log and graph the RPMs on this run as I did in the last, as we had a gusty tail wind which kind of messed up the data. I'm pretty happy with 105 km, and the next step is attaching a car alternator with a rope belt and getting some usable power off the thing.

Well that was emotional.

Had what I hoped to be the final destruction test today, which I've been a little nervous about as I need to sign off on the thing being able to take 100km wind so as to let the Nelson Environment Center know I'm able to go ahead with the first construction workshop, and they need at least a month's notice.

She peaked at 105k, backed off and held 100 for maybe ten seconds, and then catastrophically failed all over the road and very nearly took out a kid on a bike.
You can just make him out at the top left of the debris field photographed below.

So, success!

I'll of course be posting the video soon, but cursory examination has it looking very much like what gave is the bolts, or rather the alu around them, which connect the vanes to the wheel rim. Which is by far the best thing to have failed, as it's the easiest bit to make stronger.

Woot!

Realised the reason for the thing being off center was a rather dumb and unnecessary mistake of my own, won't bore you with the details, am today fixing. Also looking at ways to economise on constructing the vanes, timewise. Reckon there'll be some economy of scale doing three at once, can hopefully get it down somewhat from the current hour forty per, which is frankly already pretty much ok.
Picked up a car alternator yesterday for $40, which is pretty good, and had a look at the Nelson Environment Center where I'll hopefully be doing the first construction workshop mid next month. They want at least four weeks warning tho, so I'm going to have to hustle getting it all signed off on and good in the next week or so.

Well that didn't go well.
I've made another turbine with an aerodynamically better and much! stronger vane design, and today did another Definitely Not Destroying My Father's Back Windscreen speed trial. Thing didn't even make it to the testing road. Twice. First time the bracket holding it to the pole was too small and chewed the wood, so we had to head home and quickly make up a better one, second time the bloody bike axle bent.

It was vibrating and wobbling like crazy, I managed to put two of the vanes on rather unaligned and somehow that made the difference between the previous 80 km/h and everything's fine, and a bent axle at 65.
Bugger.

So I'm going to align and center the vanes like they should be, and add another three more on the bottom of the wheel so that the force is all sideways rather than levering the thing against its contact point.
This was always the plan anyway, I just didn't think it would be necessary for this test.

Tomorrow we're heading into Nelson to, amongst other errands, find a car alternator to be getting actual power of the thing, and an old vacuum cleaner motor to rev up and test the alternator. And a couple more spare bike wheels to mess up.
Also visiting the Nelson Environment Center, where I'm supposed to be giving a construction workshop on all this soon, if I can get the damn thing to work.

Doing stuff is haard.
Can't believe I went through almost two years of this malarky with the solarflower.

Other Tech.

Today I finally started documenting other bits of tech that I've been thinking of and possibly prototyped:
http://www.solarflower.org/?lang=en&content=othertech

I'll be adding to it over the next weeks and months.
The idea is that the project will move to a point where the solarflower is one device of many, and this is the start of the process of getting other things documented, tested, tutorialised, and made generally available and useful.

More accurate wind power average calculations.

Been trying to get this trough to Wolfram Alpha, but their forum doesn't really get used and the FB page, like all pages now, is pretty much set up for ineffectual broadcast only. I'll put it out here to see if any of yall has input.

Basically there's a problem with how most people figure out the viability of home wind power in their area, which is that they'll take the average windspeed (let's say 15 km/h), figure a turbine's power output at that speed, and thereby see how much the turbine will put out per week/month/year.
And if the wind's blowing at a constant 15 km/h then that will be accurate. Let's say about 12 watts for a typical meter diameter turbine.
But, if the wind's actually not blowing at all half the time (0 watts), and at 30 km/h the other half (98 watts) then the actual average power output is gong to be 49 w, not 12. If it's 60 km/h a quarter the time it'd be 195 w.
It's because wind power goes up by the cube function of its speed. A little more wind makes a lot more power, and just taking the average (mean) speed doesn't at all accommodate this, so people are making the decision on whether to invest in a turbine based on erroneous information.

So what I'd like to see is a calculation in Wolfram whereby the windspeed data for an area is graphed for a given period, the area under the graph, ie the total wind power, is calculated, and a windspeed average given such that that's how fast the wind would have to be constantly blowing to give you that much power.
People can then multiply that by the output of their turbine and see if it's going to be a viable investment for them.