My 1st real VAWT Success !!

[CmeBREW]

Hello guys,

      After my last series of Vawt failures, I thought I had to at least try and redeem myself. So I kept working at it and finally got what I believe is some good success with the simple SAVONIUS VAWT rotor. I am very excited about it--I think there is alot of potential with the Savonius Vawt. I did many, many different things attempting to do the Darrius type vawt, but this complex type always only went upto around 30rpm max. with no real torque.(It wouldn't self take-off into lift)  So I decided to go for the TORQUE and not the speed.

I decided on the simple SAVONIUS type to capture very low wind and breezes in turbulant areas, hoping to get at least 2-30 watts of nice CONSISTENT low power for most of the day. (primarily in the summertime--when wind is almost non-existent)

The following is just a simple PROTOTYPE of the Savonius vawt rotor. It has hard maple wood arms and pine blades. When I get settled on a good powerful design , I will make the arms out of hardened 3/8" think steel and make the whole thing as strong as a tank!

And I will custom make the very slow RPM alternator for this Savonius rotor. (cut-in probably around 40-60 rpm)

I will ask for help with coils at that time. (soon)  Here is my advancement so far:







I must say I love the look of these VAWTs. The dimensions of this prototype are 34" total diameter and 39" high. The blades are about 14" wide.  This prototype has been turning ALL DAY in a turbulant (stop and go breezes) corner of my house at ground level. It turns 60rpm in the smallest breeze and with pretty good torque.

VAWTMAN was right, these things turn mega easy! I just needed much WIDER blades!!!

I can't wait to test this thing in a real wind! (20mph+)

The front 'nose' part of the blades are simply 4" pvc plastic drain pipe. (the thin kind) I cut it in half with my table saw. A jigsaw works also.





This big 4" 'nose' is held on with only a couple of screws right now, but I found out that there is quit a boost in rpm with putting a 3/8" nut between the nose and the wood of the blade so that the wind pressure will go all the way around the INSIDE of the 4" PVC nose.  So now there is a 3/8" airgap for the wind to flow around on the inside. Difficult to explain. Here is a simple picture if you can see it.





Obviously, the wind is driven up BOTH sides of each blade in its PVC nose to keep pushing it forward. I also put 4" round (1/4" plywood) end caps on the top and bottom of the blades for better pressure. They did help.

So I am learning some good principles now about these type rotors and after examining Windstuff ED's nice Lenz2 savonius mill. Very interesting! I am still experimenting though to narrow down an even better design than this prototype with possibly an airfoil shape on the outside of the 12 to 14" blades, to hopefully get alittle more lift like ED's.

For braking in high winds, I am going to simply have each blade on an axis at the end of each arm so that during a very strong gust, centrifagal force pulls the blade outward (resistant spring) and slows it down like an airbrake. Its actually quite simple. I'm also thinking about using 1/8" plexyglass instead of the 1/4" plywood. It would look much less noticable. Or I might use thin galvanized sheet metel blades wrapped around a wood frame similar to ED's.

It has been and will continue to be ALOT of fun doing this. I would appreciate any and all comments and suggestions concerning anything to do with this!!!

If you have any questions-- just ask man.

[thefinis]

Very nicely done. Would love to see an end picture of the blade profile as still not sure even with the drawing of the exact design of the blade. Is it a half circle with an air foil mounted in the middle just behind it with an air gap? It will be interesting to see how it performs with a load. The F&P motors seem to work well with type of slow speed turbine but are only available in certain parts of the world.

For braking I say let it run. My experience is that high solidity vawts are as well off to let run in a high wind as stopping them. The large blade area catches the wind and puts about the same stress on the tower braked or running maybe a little less sideways force and a little more twisting torque when braked. Your experience may vary with different blades. This is one of the areas that vawts suffer in. The towers must withstand high winds without the option of furling and reducing the area presented to the wind.

If you are worried about the neighbors then I would stay away from a sheet metal blade unless you are going to paint it. The metal reflects light and will flash rays of bright light around in varying directions during the day. I think that plexiglass would look neat but not sure how you would bend it and I think it would crack from stress at screw holes over time. I like the look of your wood/pvc one and if anyone fussed just paint it. It would look great in blue with a big yellow sunflower on the flats.

Congrats again and the turbine looks great. keep up the good work.

Finis

[vawtman]

Cograts Cmebrew

I like the idea of using pvc pipe for the leading edge especially has the profiles narrow.Aim for a solidity around .3 saeemed right from my tests.

Ive decided to build a half scale model of the 8ft.

 Finis had some great advice for ya.

 Keep havin fun

[CmeBREW]

Thanks guys,

      Finis, you were right, those darrius vawt types can be down-right discouraging after weeks of work. You are right about the drag type being much easier. I am sold on Savonius! The picture I am about to show is the bottom end of one of the blades (I took the end cap off) so you can see it. The 1/4" plywood is only temporary. This is really just a TEST--it is not the final blade profile I am going to use. The pine wood profile here is made from a common 2x6 board and it was my latest attempt at a Darrius type vawt. The results were not good enough, so I then decided to cut some 12" wide 1/4" plywood and screw it on there to see what it would do. The rpm went clear upto 120rpm in about a 10mph wind with VERY good torque! I was amazed trying to hold back the flywheel on the treadmill motor with my hand. It is exactly like someone pedaling a bicicle -- except it goes on all day long!





This test told my alot. I know what I need to do now. I will wrap thin sheet metal around the wood profile and have it extend out the extra 4 inches. I will remake new blades with a 2X8 pine board using the dado cutter blade on my table saw. Thats the way I did the 2x6 profile you see. It is quick and easy with my dado blade!!

I also want somewhat of airfoil profile on the outside of each blade. From the photo you can see what I mean by the AIR GAP between the wood blade and the PVC plastic (using a 3/8" nut as a spacer--and the pvc mounting screws go thru the nuts to hold them in place)

This way the wind pressure goes all the way around the PVC nose for an extra boost forward and during most of the 360 degree rotation. And it really is a noticable boost in rpm. (I tried it also without the nut spacers)

Here is another angle of the rotor on the testing treadmill motor.





I also 'short' the treadmill motor leads when the rotor is going, and it don't even slow it down at all. It keeps going 40-120rpm depending on the breeze. So far thats all I've had to test it is very little bursts of 5-10mph breezes. I definitely see the potential for good STEADY low wind power. Thats really what I wanted in the first place.  Here is something like I am going to make real soon:





I think I have a very simple and useful design. I need to make the best rotor I can make first, and THEN make the ulta slow rpm alternator to match it.

Thanks for the help guys.  Any other help, questions, or comments are most welcome !!

[ghurd]

"any and all comments and suggestions concerning anything to do with this!!!"

"ultra slow rpm alternator"

Half HP GE ECM???  Numbers look creepy-close to me.  I'm usually wrong.

Jerry's tests (thanks Jerry) of stock and minorly reworked units...

http://www.fieldlines.com/story/2005/4/16/42254/0713

G-

[vawtman]

Heres a pic of the profile of the 8ft compared to the 4ft.

 Im just doing this for fun.I have 20 neo arc segments leftover from other projects and would like to experiment with a smaller stator first.

[thefinis]

Mark looks good does the inside curve match the smaller circle? I worry that on my set that the inside blade curve which you designed for 8 ft circle did not match the 12 ft circle curve on mine from just taking the profile and adding another blade to make ratios match.

Finis

[thefinis]

Since you have gotten a boost with the air gap I would try playing with different spacings(if you haven't already). Another thing that might change output is the angles at which it is mounted both the entire blade and the airfoil behind the pvc.

Thanks for the picture I see now what you have done. Looking forward to how your turbine evolves. Dang vawt bug(subspieces of the RE bug) it seems to keep one busy chasing new ideas.

Finis

[electrondady1]

congratulations"

you are obviously an experimenter.(my kind of nut)

may i suggest a tilt down tower  to aid in changing your various wings

purchasing a wind gage to do comparison testing were possible.

if you have any doubt as to the rigidity of your single point attachment

try to tie the tips of the wings together top and bottom

that is an interesting profile especially and increase in speed with a spacer.

good work, carry on.

[CmeBREW]

Thanks Ghurd,

      I don't think I'm quite ready to convert one of those GE ECM motors yet. Those look very interesting though. I will keep reading about those when I get the extra time. I already have a nice 40 mag (3-phase) alternator I'm going to use for this VAWT rotor. And I have enough mags to make another one. So all I have to do is make the 1/4" thick stator (probably 18 ga. wire) and I am good to go.







I can certainly see that these VAWTs are completely different from the HAWTs. The power (raising torque) range in RPMs is much smaller.(60-300rpm or so)

I've been looking at Windstuff ED's alternator to try and get an idea of the turns of wire. I suppose he reduced his stator to only a 1/4" to greatly increase FLUX strength to raise watts QUICKER with the much quiker power (torque) rpm range. (at least thats my basic understanding)  My terminology could be a tad off! I think I will just try and fit as much 18 ga. turns in a 1/4" thick space as I can. That still leaves me with some hook-up options later.

[ghurd]

I don't think you'd need to do any converting on the 1/2HP.  Pretty much just add diodes.

But any converting needed is super easy because all the wires are in sight and large.

One of Jerry's...

http://www.dplusv.com/Air079a.jpg

G-

[vawtman]

Hi Finis

 On this one the curve matches a 3ft cicle although 4ft diameter.Just for an experiment and to help Cmebrew.Also to help me with a stator design for the big guy.

 Its only gonna cost a couple bucks to build the spars i have leftover trimcoil from the additional blades for the 8ft.

 The little guy is retired and using his shaft and bearings on the twin towers.That should be a strong tower.

 Need to know how 4 blades work.

 Wonder how much full lenght power poles cost?Need 3 or 4.

 I will update progress.

[CmeBREW]

Thanks Vawtman,  

     Thats a very nice profile. Very interesting. We can all easily see that if it could only get up to a fast enough speed, lift would occur on that outside profile. And no drag at the tale. I listened to you to make the smaller diameter rotor. It seems very logical that with the smaller diameter the wind will begin to go into a 'spin' or swirl ALONG WITH the blades-- thus greatly reducing drag on the side opposite the direction of the wind. All 3 blades would be helping each other move forward. With big diameter , the blades are each on there own to fight against the opposing wind.

From my experiments so far, I love 3 blades the best. Forget 2 blades, they suck horribly. I learned my lesson well on that!  I don't think 4 blades is that good either. It will be alittle more difficult to start up because of a 'dead spot'. It will always stop in a dead spot i think. And it is harder to make, weighs more, and don't add anything good, i think.  3 blades is it for me from now on!!

I would certainly like to see you make that 4 foot diameter vawt rotor.    

-Thanks for help always.

[CmeBREW]

Thanks Finis,

       You are right, I have caught the Vawt bug! It is VERY interesting. I haven't had time to experiment with different spacings, or angles,or the mounting positions of the blades to the arms yet. I also suspect those things can make a giant difference. I have about a million different things I want to try at this point!!

I am already having much fun and alot of success. This rigged up rotor I made has been running almost all day long in very little breeze. I was inaccurate about it going upto 120rpm though. I timed it close with my stepwatch right in front of it today, and the max. so far is 100rpm in about a 10mph breeze. But it has very good torque! It usually is going 60rpm and thats with that terrible drag from the plywood.

The 1/4" plywood is already starting to warp though, as I knew it would. I will make the real blades this week.

Yes, I am going to paint the sheet metal a nuetral color, the color of treebark, so this thing will virtually be invisible so I can make many of them on 10 foot poles.

Thanks for advice.

[vawtman]

We will see what happens.FUN

 Your last drawing shows a perfect airfoil covered by the pipe on the leading edge.What i meant was just enough to cover the nose to make the foil easier.Will work good for ya i think though.

 Wide diameter no good has you stated.

 Pacwind and others have the same thoughts.

 If things go good this week(work wise) should have it done by the weekend.My dad said i need to stop thinkin and get back to building.

 If it spins its fun.

 Best of luck to ya!!!:>)

[CmeBREW]

Thanks Electondady1 ,

Yes I am a Mad experimenter nut like many others here. Its a great hobby to keep my mind off of 'the crap of life'!(sounds like a tv show)

You are right, I really do need a wind meter. I hate quessing with the numbers like I do, since ever MPH counts alot. They are expensive--I will have to keep pinching my pennies.

Tieing or reinforcing the blades together is something I probably will have to do. I finally got what looked like a 15mph short wind and the rotor went at least 100rpm and started swaying the 2x4 pole back and forth violently. It almost snapped the 2x4!

And that was with the treadmill motor leads shorted together! So I was fortunete. I moved it to a more stable, safer testing pole in the big yard for better winds forecast tomorrow. I want to see what she will do!!

Talk about being a Mad experimenter,,check this out.

I came up with this idea this morning. I was standing on my toilet, fell and hit my head,, and when I came to, I drew something on paper. I call it the 'Flux rotor blade'. (No, just kidding! I didn't fall. Here is the idea--I think it has alot of possibilities for mega torque!)

I went ahead and started making one of the blades for testing later this week:

Check it out!

It uses the same thin PVC drain pipe. One section is $7 for 10 feet.  So I am making this blade out of one section. It has 9 sections are curved and mounted together with treadrod and nuts for spacing. It takes ALOT OF NUTS to do this man! I am trying to make a crude airfoil shape too.



I drew it out on paper, and it looks like it just might Double or triple the torque!(who knows!)  Everything looks right in the rotation! I can put a sheet metal pointed tail on the end for no drag in the back. This complex concept blade is 40 inches long by about 14-16 inches wide. I ran out of nuts though. It is quite rigid after you tighten things.



It really don't weigh as much as it looks. The air flows around each profile and pushes at a much steeper angle.(and many more times with each section per revolution)

Difficult to explain.  

If it works, the rotor will be like an 'all-natural Sterling engine'!!!

It should kick AS$#$%!  

We'll see. I'll know if it has any merit very soon.   -Thanks friends!  

[CmeBREW]

Today I woke up to better wind (looks like 15mph)and it is going at least 120rpm+ now!! She's really cooking now!

I have the vawt in a better location now. With that strong torque I bet it is doing 40 or 50 watts of potential power right now.



My little 4 foot windmill isn't even turning--the piece of junk.

I am worried about the  centifigal force on the weight of the blades if a 20mph wind gust comes along. The blades may rip off the angle iron mounts and the bolts.

I will have to email ED to see if he thinks I will need to make the air brake mechanism. I'm still not sure if it will reach a certain point and self-regulate. So far it is not.  I have to go to work today though. One thought (fear) comes to mind:

"She's breaking up scotty!!"

I hope not.  

[pepa]

cut some spacers out of plastic pipe insted of all those nuts, pepa

[CmeBREW]

Thanks Pepa,

     I am not so sure about that concept blade now. I've been looking at it for days, and I think I was dreaming again. It will not add up torque like I was thinking. For a very low wind vawt, I'm now thinking that ED's Lenz2 'big scooper' Vawt can't be beat. Its like 3 giant scoop shovels or meat hooks grabbing LARGE volumes of wind and pressure on each rotation.

However, I am doing something alittle different though now--just to see what happens. Its easy and much larger than the vawt I just experimented with. It should be a big, drag oriented, low rpm, mega torque machine. (three; 5 feet long blades that are over 15" wide ea.)

There just big straight boards with PVC fronts. If it works good, it will weigh alot, but is easy to make. Takes some heavy steel and welding in the middle to hold this heavy thing together on the wheel hub though. The down side is each blade will weigh at least 12 lbs. and so the center part (thick steel arms,mounts,etc) will weigh even more. (total of 50 or 60lbs spinning on the trailer hub)

Should be exciting trying to control it in a 50mph gust. Of course, It will be tested in a very safe giant yard/field, completly isolated. I would like to keep it under 300rpm no matter what! (centrifagal air braking, or???)

Today I put the big board blades on my small treadmill vawt testing pole, and it sure had WAY more Torque in almost no breeze. The heavy blades are bent down though.

Hopefully tomorrow I can get an idea of what it will do.

 I'll try to show pictures on this thread this weekend.

[thefinis]

I will bet that you are just fine. You have the solid wood airfoil for stiffness and strength. Those thin plywood wings will probably bend with the force and cut power/rpms back anyway at higher wind speeds. It is the mounting and tower pole I would hope holds.

I had a boss at one time who liked to remind us that all our energy should not be spent on just trying to reach our goals because some of it needed to be spent on being ready if we succeeded. Success can be scary if you are not prepared for it.

Have fun and even if it wrecks just rebuild it better.

Finis

[CmeBREW]

These things are really cool! Talk about simple, I've been doing some initial testing with these big 1/2" baltic birch plywood straight blades I just made, and the torque is amazing. (each blade is: 5' long by 15.5" wide ; weighs 11 lbs ea.)





This is ONLY A TEST though. Thats why the blades are crooked and bent down. The weight of the blades is twisting the small arms they are mounted to. Baltic birch keeps its shape pretty good (I hope!) as long as you keep a couple coats of exterior paint on it. Tomorrow I will make some thick, strong, hard wood arms and straighten the blades up. I am also going to increase the diameter from 34" to 40".

If you can see a small weed moving, this thing starts up and turns! It is usually going 30-60rpm in a breeze, and then a 12mph (quess) comes along and it spins up past 100 rpm with incredible torque! It takes me 30 seconds to slow the blades down with my hand from just 60rpm. Tomorrow, I am going to put on the 'PVC boosters" on the leading edge and that always makes it go MUCH faster. It is really neat- I kid you not. It could be a very nice alternative for those who can't put up a 10 foot HAWT high in the air due to very justified fears of stupid (unreasonable) local laws and ordinances. Even though I live way out in the 'country' with the farmers, I am also afraid of this. So I would rather keep a low profile. They just keep passing more and more stupid laws. Its unbelievable.

I have to finish my low rpm alternator real soon so I can start giving you all some REAL power numbers. (hopfully next week)

The cut-in will be about 30rpm hopefully.

But I think this will need some kind of a powerful centifigal air brake though to keep it under 300rpm. That makes it more difficult to make. From what I'm seeing, it only keeps speeding up with the increased wind speed.  When the design is done, it will be made like a TANK and look purdy too!

I know this thing goes slow, but it's like 'Conan the Barbarian' pedaling the bicicle!!  I can't wait to keep improving this.

[CmeBREW]

Wow, this is ALREADY looking promising!. I got the time today to re-make the arms much stronger with thicker and wider hard hickory wood. I increased it to 40" diameter as I said and added the 'PVC boosters'.

It sure DID add some good 'boost' to the rpm and torque.





It turns clockwise and starts-up extremely easy-- if it ever actually stops. It hasn't stopped for hours now in a 5-10 breeze.(I just got this new modified version up a few hours ago. No big winds yet though.

It went about 120rpm in about a 12-15mph (guess) even with the bigger diameter. I hope it holds together! Sometimes it sways the treated 4x4 pole some and it gets me concerned. I see I will need a very strong and sturdy steel pole (probably 4" diam) to mount this on. (about 10' high above the ground/ without wires) The treadmill motor and wood center is still just a 'testing vehicle'. I need to complete the ultra-low rpm alternator on the trailer hub next week and mount this on it, and see what this baby will really do. I didn't have time to put the 'end caps' on yet, but that adds to it some too.(increases the pressure in the PVC)

Ignore the power lines in the background. Also Ignore the 'finger clamps'. I didn't get time to experiment with turning the blades at different angles yet. There is only one bolt in each blade mount right now. The clamps are holding down the other side until tomorrow. The angle of the blades is about the same as the LENZ2 right now. (about 10 degrees; The LENZ2 is 9 degrees I believe)

You will notice the PVC sticks out further on the OUTSIDE of each blade. I thought it would produce more torque that way. There is also an AIR GAP with the PVC on the INSIDE of each blade for the wind pressure to keep switching back and forth in the 'PVC nose'. (at least thats my theory at this time)

I glued 3" (5/8" square) long little wood blocks on the top and bottom of each blade to screw the PVC boosters to. (always use waterproof glue)

So the PVC air gap on the inside of each blade is the thickness of the little wood blocks---5/8".

I actually feel the torque on the treadmill flywheel when it is going about 60rpm and more, and it is very strong! I can't stop it with my hand. I can't wait to see what WATTS this is capable of. I know its nothing like the bigger watts of a HAWT, but I was hoping to get more of a CONSISTENT 5-40 watts in low winds.(under 14mph)

We will see.

I wanted to see what big STRAIGHT FLAT blades would do first, and then I will move on to making and experimenting with curved blades and airfoils. I need to know what flat blades can do first, in order to know I am improving performance with more complex curved blades in the future.

It has been very interesting and fun so far. I am going to DOUBLE my efforts to get that alternator done ASAP!! I will do a test coil with 18 ga. (when it gets here) and ask for opinions at that time real soon.     -Thanks guys!

[DamonHD]

Very interesting!

[CmeBREW]

Thanks Damon. It is interesting. I have some unfortunate news though. But before the bad news, heres a nice picture of the prototype all painted up just yesterday:





The bad news is--today the worst thuderstorm of the year popped up within a few minutes and I was working inside and didn't know it until it was too late. A small tornado hit a couple miles down the road and knocked over trees in every road and power lines. All power is out in the small town. Here, where I'm at, about a 70 or 80 mph GIANT gust of wind hit in seconds and tore all three blades clear off my rotor!! The blade in the front flew about 75 ft away. Amazingly, it Didn't damage the plywood blades at all, nor the PVC boosters!!!





It actually bent and twisted the angle steel I had hardened with my propane torch. One thing is for sure, it did NOT self-regulate!!

I DID get to see some of it happen, but it was too late for me to get near it. For several seconds, there was about a 30mph gust, and it turned fast at about 400rpm, and then this GIANT wind gust came immediately, and it bent the angle steel and all 3 blades went flying. It all happened in just seconds. I couldn't do a thing!

I know i made it quite 'shanky' (or;flimsy) for testing purposes. It wasn't going to be like this for long. I did not expect a sudden storm like that. I can see I will need some kind of automatic braking system for these big blades. Even a big centrifagal 'air brake' would not have had a chance either. It makes it alittle more difficult to make.  I was having what I thought was very good low wind testing results before this happened.

Oh well. I was VERY fortunate. I will mount it to the trailer hub with all steel mounts and arms onto the alternator next week hopefully, and get some REAL WATT results.  I will watch it even Closer this time! They've been calling for thuderstorms almost every day now for the last 2 weeks, and nothing came until now!

Yes, this IS 'testing and development'. It is good to have a safe distant testing location! I will have it back up very soon, but this time made like a tank!

I have to think up some sort of auto-brake mechanism.

[DamonHD]

Wow!  Well that's one way to stress-test your new designs!

Maybe you need to make it a little stronger, so that it can survive a once-per-couple-of-years event, maybe not even quite as strong as you just had.

Clearly your blades/boosters are fine.  Maybe you could make it possible for them to break off more cleanly in a really nasty gust like you just had, sparing the axle and preventing too much damage to them?

Rgds

Damon

[CmeBREW]

OK.  

After last week's catastrophe, I spent every extra minute getting the prototype VAWT back up and spinning.  I had to shorten the testing pole again. If I have to go any lower, It'll drag on the grass! Normally, you should have this at a SAFE height, even for testing.(The bottom of the blades above 7 feet)

It won't be this low for long. I like this photo-- It almost looks like 'divine approval' or something.





This time I mounted it on the small trailer hub with much stronger, thicker angle steel on the top AND bottom of each arm, to secure each big blade better. I only have 2 of the 4 bolts in each blade mount so far. (1/4" bolts)

The alternator is not totally complete or on there yet-- Need a couple more days for my coil wire to get here so I can make the stator. Everything else is done. But for now, I just love to watch it spin all the time!!










The angle steel is between 3/16" and 1/4" thick.

The arms are almost 1" thick solid hickory wood, sandwiched between two 3/4" plywood circle discs with 1/4" bolts and some screws. It is much stronger than it was. It is not made quite like a TANK just yet with all steel----but I want to make certain this thing is 'worth the watts' before I spend all that extra time and money on thick expensive steel.  

Now, the over-all diameter is 41". The blades are still 5 feet high. In a small breeze, it is usually turning 30-60 rpm -- even during most nights. It has pretty good torque even going this slow.  It will keep going faster with the stronger breezes/ winds -- so I have to be careful for now.

Now, all I have to do is make it survive high winds hopefully with the alternator hooked to a heating element.(during storms)  We'll see. I'll post soon with the power WATT results and I'll also try to show a video clip of it with my brother's expensive digital camera! -COOL!

From now on, I'm going to tie the rotor down with a buggie cord until the alternator is in there and producing power.  This VAWT is virtually invisible from the road a couple hundred yards away! It blends in nice with the cows!