Painted Canvas Over Plywood, Vertical Axis Wind Turbine

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About: For the past decade or so I've been very concerned about the planet remaining habitable in the foreseeable future. I'm an artist, designer, inventor, who's focused on sustainability issues. I have focuse...

Hello Instructables Fans!

Thanks for all the likes and comments, I appreciate each and every view. I'm an introverted exhibitionist :-)

I first encountered painted canvas as a waterproofing and structural system on the decks of my 1960's era Tahiti Ketch, a 32ft live-aboard sailboat, the perfectly named "Audacious". I was surprised to see how well the painted canvas decks had lasted, and kept the wood below pristine. It had kept the boat dry and leak free, over a planked deck for 40yrs. It was original according to the son of the builder who we bought her from. Later I read more about painted canvas canoe's, and about people using it as an alternative to fibreglass in waterproofing.

I've used a lot of fibreglass, with polyester and epoxy resins and I'm looking for more environmentally friendly, lower toxicity options. As my previous instructable shows in the 3D printed central mast, I've been making use of some hard plaster and concrete options, please check it out, and vote for it in the concrete contest.

After a lot of time thinking about ways to make my turbine work more accessible, and constructible in large variety of infrastructures. I concluded that painted "fabric" over plywood was a good place to start. My first guess is that a turbine shell could be completed for less than 50$ materials, and from what I've done now I can see, it could be done for much less by resourceful people.

Right now it's almost ready for testing and I could use a bit of support, moral and physical, so it's time to introduce it to the world.

This will be a living document until I'm done with the first round of testing the turbine, starting with testing the test system, the alternator/dynamometer (an interesting instructable you should vote for in the Sensors contest! ).

Please check back to see progress, I expect to finish testing sometime before September.

After the Paint contest closes on July 29th, I'll start a change log to make it easier for people to see updates. It's been suggested that I move the project to GitHub, or other service. I don't know enough about it to do it at this point. Feel free to inform me of better ways of creating an open source hardware system.

I will eventually have a longer document specifically on the history of the design, how I arrived at it, and some directions I hope to take it. If you'd like you can read some more about the project on my website, or check out my youtube videos. I've been busy building and so haven't updated my website in a while. It's got some background material on the project but has never been a polished site. Here's a link to it.

www.artinventing.com

This is primarily a document is about how I made this version of the turbine, along with notes about how I'd do it differently next time. It's definitely worth doing for those with a windy spot and some determination to make their own electrons jiggle! , and I look forward to hearing from people with suggestions. I think especially the folks with experience doing stich and glue boatbuilding will have some good ideas.

If you're interested in building a turbine like this, what I suggest is that you keep an eye out here for news, and follow me on youtube, or Patreon.

I suggest waiting at least until I publish results, which should be fairly soon, hopefully early tests within weeks and a full power curve within a month.

My goal, if test results warrant further work on this version, is to release sets of plans, and kits, for versions in sheet metal, and plywood, then fabric(telescoping), and perhaps cardboard, and then cement! That's right, ceramic wind power!

I'm going to release the templates that I've used on this one for those who can't wait, but I strongly suggest waiting.

Supplies:

  1. 1/8" doorskin plywood, enough for 2 turbines if cut carefully.
  2. 2 gallons of latex paint
  3. fabric for "canvas" Lots of things might work, I used Reemay, a polyester non woven fabric you can find in garden stores. Reemay
  4. Wire for tieing plywood together
  5. 3D printed "mast" link to instructable
  6. 3D printed alternator link to alternator instructable

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Step 1: VAWT Skeptics

VAWT skeptics, It's completely reasonable for you to be skeptical, even wise. It's been consistently a lot of promise and NO delivery. Not just VAWT's, but small wind turbines in general have turned out to be a poor investment for most purchasers.

I have looked into every VAWT I could find in the past 15 years, and the best performance in air, at sizes below 20ft diameter, is 11% wind energy to useful Watts, with perhaps one outlier which was too flimsy to survive long term testing reaching 17% peak in very high winds.

In contrast Conventional Horizontal Axis Wind Turbines (HAWT, propellor style turbines), in the 20ft diameter range and larger, like the well respected Bergy products reach 31% wind energy to useful Watts (this means that the including electrical losses the wind energy to shaft power efficiency is likely closer to 35% .

So the reason that there aren't more VAWT's around is because HAWT's provided more energy, for lower investment. BUT!!, the reason the small wind turbine industry, VAWT and HAWT have shrunk while Solar has surged ahead isn't just that Solars cost has dropped, it's because even the best small HAWT systems only provide good return on investment in the very best locations. In most sites they will cost more energy to produce than they will make, small HAWT, or VAWT.

Right now the whole small wind turbine industry has been out ROI'd by PV Solar.

However, IF a small or medium size wind turbine: were made from mostly renewable/recycleable, low cost materials, could be assembled by local minimally skilled labour, and have very long lifetime, it changes the equation for many places where PV is unaffordable, yet materials and labour are available.

There are a lot of windy places in the world that need jobs and cheap green energy, but can't afford to build solar panel factories, including the "rust belt" of the USA.

Step 2: Starting the Build, Layout, Glue, Cut

I had the 2 pdf's printed twice (4 pages)at my local print shop for about 5$. I cut them out and joined them to have 2 templates. I stuck the paper templates(reinforced with packing tape) to plywood and marked around them. The second template I cut into two pieces as it was unwieldy and thin in the centre. I ended up with 2 large parts, and 4 smaller parts. I glued paper to two sides of one part as a test, another part I used white glue and heavy paper drywall tape just over the fold lines. All the parts, taped, papered or nothing, got a coat of PVA glue.

Then, after carefully marking all the lines, I used a knife and scored all the bend lines.

This was all a bit of a mess, were I doing it again, I think I'd get the paper templates printed full size on heavy paper, or canvas, then I'd glue the paper templates directly to the plywood, and then more paper to the other side of the plywood. I'd then use a hand router and guide rail to cut all the bend relief lines, and bandsaw out the profile.

Step 3: Assemble Sides

After cutting the relief slots on the inside of all the bends, carefully prebend each joint. If joints don't bend easily enough, don't force them too much, instead just cut a little more out of the relief joint.

Something that might have saved me a lot of work, is before the joints are bent, or relief joints cut, I should have drilled all, or most of my tie wire holes.

With the prebend long piece, and it's mating shorter part, join the top vertical seam between the two with tie wire. Then the next horizontal seam, and on and on. I found it handy to have a good size work space for the turbine to lie down in, and had a number of heavy blocks and things to rest it on as you stitch it together. Continue with the second smaller piece, and now that you are an expert, join the 3 parts of the other side.

Step 4: Prepare Alt and 3D Printed Core Then Hang the Sides!

If you've got this far, hopefully you've at least looked at the 3D printed central mast, and alternator. Now is the time to join them together, and mount them on a shaft. I used a piece of 1" extruded aluminum rod as shafting, and it required a lot of work to get down to a real 1" that the bearings would fit onto.

Once you've got that assembled, carefully fit a turbine side onto the mast. I think this is easiest in the vertical position. The uppermost orange "wings" on the sides of the pink plaster filled structure, have flat sections that make a great place to first spring clamp the sides on. Once one side is on, drill holes in the flat clamped area of the shell and 3D printed mast, and tie through the hole loosely with wire to temporarily hold the first sheet on. Predrill holes for the second sheet, and tie it in place though the drilled holes.

Starting at the top, and working one edge then the other, tie the outer most edges of the two plywood skins together, drilling holes as needed. I used a small square pointed scratch all, to hand twist drill most of these holes as it's just 1/8 plywood with a bit of paper skin.

Copper wire is good as it won't rust if it gets left in place, but it breaks much easier than steel tie wire. Galvanized steel worked fairly well. I'd be interested to hear from plywood stich and glue kayak builders on what they recommend these days.

Step 5: Paint It UP!

This parts pretty simple. I did it with the turbine vertical, but horizontal might be a bit easier. I used a bunch of left over latex primer, lots of it, and reemay polyester cloth. I started at the bottom with strips that were wider than the blade and about 2x as high as each layer (around 35-40cm, by 50-60cm). I brushed paint on the surface, stuck the cloth to it, and painted it again, then did the next layer with big overlaps, shingling my way up. I did 2 layers on both sides, and lots of paint, lots and lots of paint.

Step 6: Sanding ;'{

I used commercial probond wood filler to fill in big low spots between overlaps of sheets, and anywhere needed to smooth it out.

Then lots of sanding, lots and lots of sanding. The best trick I can pass on here is to cut sanding blocks from styrofoam, ideally from packing you've been saving to recycle. Use the thin double sided carpet tape to hold sandpaper to the styrofoam sanding block. This works especially well if you carefully round the styrofoam sanding block corner and apply the sandpaper over the corner. This way you can sand any radius you want.

Step 7: Tape the Edges

The two plywood shells don't perfectly meet in this early version, and I wanted to be able to take the shells off if needed, so at this stage, I carefully taped the edges together to seal the seams.

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    27 Discussions

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    Drewrtjoshua.artist

    Reply 6 weeks ago

    I agree Joshua. I wish I had more time and maybe a few clones! I will return to showing these can be made from renewable materials. Next though is to show a very simple method for building them from sheet metal, after I've done a bit of testing on this model.

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    Drewrtterezkaterka

    Reply 6 weeks ago

    Hello Terezkaterka, I used google translate to interpret your comment and got "seems endlessly difficult".

    Not really sure what you meant, or how close the translation is. I did find this one difficult to build, but it's the first one, and it'll get easier as more gets figured out.

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    JonathanS365

    7 weeks ago

    Beautiful design, of course, and it addresses the varying wind direction problem. I wonder how much more efficient this is than the simpler pop bottle design?

    Pop bottle wind turbine.jpg
    2 replies
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    DrewrtJonathanS365

    Reply 6 weeks ago

    I have never seen test results from the pop bottle, or squirrel cage type multi blade rotor, though many people on the internet have claimed they work, they also seem unwilling to comment on how well they work. As we've got no data on the pop bottle, I'll suggest that it's unlikely to be better than the historical Savonius turbine, which though the Blackwell report from the 70's claimed up to 21% efficiency, this number has never been real world verified, and many people who've built Savonius's expecting 21%, found it collected a fraction of that. Most recently in 2010, a researcher (Ian Ross, Wind Tunnel Blockage Correction factors) working to understand why Savonius, and other VAWT's were testing in wind tunnels much better than the real world results. He found that the blockage calculation used on conventional turbines returned erroneous results, and that the more likely real world efficiency for the classic Savonius turbine is only 5%! My previous turbine, while under observation from an engineer, tested between 29% and 31%. It's likely that the pop bottle is less than 5%, and I'm hopeful that this turbine will be in the 30% range, so you could say that for every 1 of mine you need 6 pop bottle types. Pop bottles are cheap, but good alternators are not.

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    DrewrtJonathanS365

    Reply 6 weeks ago

    Thanks JonathanS365, I am glad you understand the wind shift problem conventional turbines face. Another advantage is that the foil profile is deep, and will tend to average out turbulence, where a thin bladed turbine would stall.
    The pop bottle is a good example of someone who understands half the problem. People focus on “catching” the wind, which I think is understandable. Another thing to consider is the letting go part :-). .. If a volume of wind has X amount of kinetic energy embodied it, and you extract 100% of that energy, you now have stationary air. Something needs to move that air to make room for more turbine exhaust. A key to very low Reynolds number airfoils is fineness, thought they may sometimes have a lot of camber, they are generally thin and sharp edged. At its widest a conventional Savonius rotor is 100% solidity and at it’s narrowest, 50%. Mine is 100%, then 20-30%.

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    hatch789

    7 weeks ago

    I'd be curious what you think of my project? Harmony VAWT ...I'm working on finishing the prototype now to gather performance data but it's taking a LONG time because I'm working alone on a small budget in my spare time. CreatingMoore.com will lead you to the links.

    7 replies
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    Chimongerhatch789

    Reply 7 weeks ago

    I’ve always been interested in double helix wind gens, as it seems most efficient at handling capricious winds, and, handling high or low windspeeds without using governors much. Glad you posted this!
    We have a tall snag (that’s a standing tree trunk that has been cut to shorter height, living or dead) out back, that fairly cries out to get topped with a wind gen!
    For VAWTs...my questions are:
    1. With the alternator at the base of it, how does it cope with rain? How to prevent rain getting into the electronics?
    2. The taller those VAWTs are, the more torque off-center...isn’t it hard on the lone base attachment, and, won’t it inhibit ability to crank out watts if a bend happens from a high wind?
    3. If a double helix is tethered at both ends, and mounted horizontally, with an alternator at each end, couldn’t that almost double the watt-output, as well as stabilizing it against high winds?
    4. Any thoughts about stacking, or mounting multiple, smaller windgens along a roof edge, or vertically on a pole?

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    DrewrtChimonger

    Reply 7 weeks ago

    1 In my design the alt is generally enclosed by the blade.
    2 With mine, the turbine blade revolves around a stationary central mast, with the main bearing quite close to the centre of aerodynamic force, so there is no torque moment on the bearings, only on the heavy non rotating axle.
    3 mounting Horizontal, etc, lots of thoughts about different ways of mounting and application, but not the right venue to discuss.
    Thanks

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    Drewrthatch789

    Reply 7 weeks ago

    I hope this doesn't show up as a double comment, as I wrote a reply that seems to have disappeared. I like the look of what you are doing, and your retract mechanism is interesting. I'd seen it in my VAWT research previously. What I see though is that the first problem of any VAWT, or HAWT is how much energy can you collect, relative to the energy embodied in the device. If you look at the study I quote from the Netherlands, most small turbines, VAWT or HAWT will not make enough energy to even pay for their construction, in most locations. My understanding of the aerodynamics of these Savonius type systems is different than most peoples. I see them as unfolded Tesla Turbines, boundary layer systems that function at very low Reynolds numbers. With that in mind, I don't see how the fairly conventional Savonius geometry you are using will collect much energy. It's my understanding that geometry like you are using is likely to give you between 5% and 10% efficiency (google wind tunnel blockage correction Ian Ross I think?) What I'm about to do is strap mine to a rack on a truck, and take it for a drive a various wind speeds and loads, and develop a power curve. I think that would be valuable for you as well. I'll be posting an instructable on my test system that you might want to follow.

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    hatch789Drewrt

    Reply 7 weeks ago

    Interestingly the first university to get back to me with Wind tunnel data was showing a cP (Coefficient of Power) to be about 51% but I can't figure out how to convert that to efficiency numbers. Not having much luck with google searches. I'm still building my full scale residential prototype and will do testing with that but they did a small 3D printed version like my first one I show in videos (the pink one).

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    Drewrthatch789

    Reply 7 weeks ago

    The classic reference on the Savonius wind turbine is the Blackwell report, which found a peak power geometry after trying 2 and 3 buckets, in various overlaps and hights, found 21% peak Cp, all in a wind tunnel. No one that I've found has ever repeated these results in the real world. In real world testing 5% is much closer to reality for the classic geometry. In 2010 a researcher examining this very question, why do some VAWTs seem to do so well in the wind tunnel, but not in the real world. wind tunnel blockage corrections: an application to ... - ETD (OhioLINK)https://etd.ohiolink.edu/!etd.send_file?accession=dayton1271306622&disposition...

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    hatch789Drewrt

    Reply 7 weeks ago

    Not sure why my other reply didn't post but wind tunnel testing on a small prototype 3D printed with mine showed up to 51% cP which was astounding. I just can't figure out how to translate that into Efficiency %. Not having much luck with google searches. That was with 3 scoop pairs. So in my design that's 6 scoops total.

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    Drewrthatch789

    Reply 7 weeks ago

    Cp is a more precise term for efficiency. It stands for Coefficient of Power , and 1 would be 100% so 0.51 would be 51%. Efficiency can mean other things than this, so engineers prefer Cp as it’s specific

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    FloridaJo

    7 weeks ago

    Cool. I am particularly interested in the bearing. What type is it and do you have a link to one?

    Thanks

    4 answers
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    pjcruxFloridaJo

    Answer 7 weeks ago

    I am also interested in the bearing. I also do not understand the "3D printed shaft" as well.