Painted Canvas Over Plywood, Vertical Axis Wind Turbine

Intro: Painted Canvas Over Plywood, Vertical Axis Wind Turbine

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.

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.

Comments

[KarthikeyanSrinivasan]

Hi Mr. Drewt,

Have no words to express my happiness when I saw this. I was looking for a project which I can make for Grand Parents home so I could offset a little portion of their utility bills. I am going to try to fabricate this. Once a significant progress is made I will share the updates.

[cromlegionar]

Hey, i wanted to congratulate you on your awesome project! I'm sorry to bother you, but would it be possible to supply the stl's for the 3d printed mast parts? If you already did I am too blind to find them..

[Drewrt]

Hi Crom, I've added the .stl for the core print, as well as for it's 6 (3 sets of 2) "wings". I've also added the .step for the core part if you choose to redo it in sheet metal. I'd create a 3 or 5 panel sheet, with the top, and both flat sides, then flanges to join to a bottom plate, which if steel can be the back plate for one side of the alternator. The angular edges could be tabbed and bent, so the skins can fasten to them. It doesn't have to be as complex as I've made it. I'm open to supplying more help, but I'd like to know more about who, where, and when the build is.

[Novice3dp]

hi, firstly wanted to say thank you again for creating such an amazing design, i am getting close(ish) to assembling everything and I noticed that the mast.low stl file seems to be the same file as the mast.body stl. I was wondering if it was at all possible to get the other file(i noticed there was a different looking piece in the pictures:)
thanks again for such amazing work
novice 3dp(btw the plywood templates worked a treat, but i ended up using bent metal fixtures to further increase strength)

[Drewrt]

Keeping organized is not one of my strong suits. I am sometimes disorganized in my .stl nomenclature, and I often generate more than 10 stl versons of parts, those file names don’t tell me as much as you’d hope. Send me a progress pic, privately if you’d like. I’ll be more inspired to spend time digging. I’m working on stuff that’s got priority. You may get a gift ! :-)

[Drewrt]

Hi Crom, Thanks, my testing of it confirms for me that it is of higher efficiency than my last turbine, which was indpendantly tested to Cp 0.29-0.31, and it self starts reliably. This makes it between 50-100% better than the Gorlov varieties and as much as 300-500%% the energy collection of a Savonius (Cp, 0.05 -0.10 google Ian Ross, wind tunnel blockage for why Sav is so low, when so many wind tunnels have rated it closer to Cp 0.2). I’ll dig up the .stl and maybe see if I can easily create a version of it that you can edit easily. If I were doing this again, I’d make this part from a water jet cut sheet with the top section being the center, and folded down to form sides with cutouts and bend tabs to join. Ahh, I wish I had more time, more hands, or clones....

[mariendbesten]

Hi I really like your wind turbine design! However, when I tried to recreate it, I discovered that the .dxf file from the convex of the turbine blade is not right. It just looks a lot like the concave file, and differs from the pdf file.

[Novice3dp]

hi there, i love the design,i think it's incredible, and I was wondering if the dxf. file for the concave pieces was available as it seems to be the same as the convex file and both the pdfs are cropped unfortunately. Thanks :)

[Drewrt]

Hi Novice 3dp, yes, I see now that I've exported the wrong .dxf. Where are you located, and are you planning a build, or just an information collector :-) ? I've not got a lot of time right now, and while I'd like to support a Maker, I have to prioritize my time. It's a pain for me to get back to that project right now, so I'll put it on my list of things to do, more info from you might get more priority on it. This was just a test project, and it actually worked better than I'd expected, not really a set of plans. I'll have a new version for sheet metal, with connecting tabs, and precut rivet holes. I'd suggest holding off a build. But, If I recall correctly the .pdf's are cropped, but the two parts fit together, so if you print out 2 pdf's then cut out all 4 parts, 2 sets of 2 parts attach together to form each sheet.

[Novice3dp]

Thanks so much for the answer, and yes, I am planning on building it with a group of people as a communal project! I was wondering what size plywood you used as you mentioned it was 1/8" thickness, but the dimensions would be great:).also, how exactly did you attach and bend the different pieces of plywood together to the right angle?using wire?Thank you so much and good luck with your current project!(this project is absolutely incredible btw)

[Drewrt]

With the layout I’ve done, I used about 60% of one 4ftx8ft sheet of mahogany door skin plywood.

As I’ve said previously, I didn’t release this as a complete instruction set, more as a pointer in a direction, and I still suggest waiting till I release the next set of plans. If you want to move ahead sooner, then I suggest visiting with some people who’ve built stitch and glue kayaks. That is the closest analog construction I can think of and if you show them a photo of what you are trying, they may have some very handy tips. As to how to bend the plywood to the correct angle, yes, I worried about that too. In fact the larger issue is that the plywood hinges can tear pretty easily, but as long as they remain intact, then it will only go together when the angles are right, so you can’t really go wrong, except by tearing the hinges. One thing I might do to help make the hinges stronger is to start by printing the templates on heavy duty paper, then glue the templates to the plywood, so the paper can be part of the hinge. The glue saturated paper makes a much stronger hinge than the plywood fibres. I’d glue paper to both sides (one side template), cut to the template, then just transfer the score lines needed to the far side. Also, I used a box cutter and a lot of patience to get the scores cut. A much better job could be done much faster with a router/trimmer, and then a wider flat bottomed cut could be made. A 3/16 flat bottomed grove cut through the top and core layers of the plywood (2/3 of 1/8 ply+ paper 2 sides, you do the math ) would make a much better hinge. I might also pre drill wire tie holes.

[joshua.artist]

I bet a dremel with it's little router attachment would be perfect for your cuts.

[Drewrt]

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.

[terezkaterka]

Zdá sa mi to nekonečne zložité.

[Drewrt]

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.

[JonathanS365]

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?

[Drewrt]

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.

[Drewrt]

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%.

[hatch789]

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.

[Chimonger]

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?