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Forum Index : Windmills : 1977 Savonius
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| ol_jon Newbie  Joined: 19/10/2011 Location: United StatesPosts: 3 |
I am in the process of researching a new (to me) vawt, the one covered in 1977 Sandia. since i'm new here, i'd like to simply state that my location/situation kinda demands a vawt type unit. I flew a dual-helix for several years 'til wear and tear demanded i take it down. I believe that Glen has experience with savonius (Sandia) and, I'd hazard a guess others probably have too;so I'd like to shorten my learning curve! I have the dimension formulas thingy, but have recently seen at least one web video that claims(?) this unit is not all that great in comparison to other savonius configurations; U-tube is not always all that reliable, however. I would greatly appreciate any input/thoughts on construction/performance any of you might have, experiment with larger units tends to wreck my already tight budget thanks again ol_jon |
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MacGyver Guru  Joined: 12/05/2009 Location: United StatesPosts: 1329 |
ol_jon Welcome to the 4m! Kindly share the link to the web videos you mentioned you've been watching so the rest of us are all on the same page and maybe we can help you some. Also, it would help if we knew what kind of power you expect to extract from the wind and if the wind in your area is strong and gusty or slow and constant. Most here are not strong proponents of VAWTs but there are some hold-outs here and there and I for one will try to help you if I can. I swore I'd never build another one, but there's one partially completed sitting on my workbench right now; so much for swearing off stuff, eh? 
. . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
I did make a small Sandia Savonius a few years back. About 900mm high and 300mm wide. It spun pretty good, faster than I expected. But I never measured its power, and had nothing to compare it two, so my finding are very un-scientific. One problem with many of the VAWT designs is they are hard to scale up due to the surface area of the "wings". On a Savonius there is a lot of area to cover with sheet aluminum/steel/whatever, and you also need the frame to support the sheet of material. Thats where the HAWT's shine, easy of build and lower cost, all you need is 3 skinny planks of wood. But the VAWT's do have a place, and are sometimes the only option. Medium scale builds like a Savonius made from a 44 gallon drum cut in half do work out well for torque and low cost, but when you want to go bigger, the economics come into play. The Sandia version is a more complicated shape, so harder to scale up. Its also worth looking into the Lenz2 design, good power with less material needed for the wings. But I myself would like to try a Miller. I built a tiny one, about 300mm square, driving a little stepper motor, and it spun fast! The Miller is a simple shape, basically flat wings with a lip at one end, so could be made from plywood on a timber/steel frame. It would be easier to scale up. Link to Miller discussion. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
[Quote=Gizmo]One problem with many of the VAWT designs is they are hard to scale up due to the surface area of the "wings". Back in the day, I found a way around all the mass whirling around on a VAWT. The yet-to-be-finished VAWT on the bench right this minute is just such a creature, but I've got too many plates in the air right now to tackle it. If anyone is so anxious they can't wait, PM me and I'll explain how it works. It is just a matter of time before I complete the thing. It has all the plus features of a Savonius as well as being self-starting and producing high torque. It runs very quietly and the total mass spinning up in the air is less than a full can of Coke! I really don't have time to start a thread on it here and now. I'd rather do that as a "build". It's so simple, it'll make you giggle. Hang in there. The off-the-shelf ax-fx is almost done and when it's flying, I'll do this VAWT. I'm loading the ax-fx magnets tonight. The rest of the mill except for the furling tail is already welded up and all that's really left to add is the stator. Unfortunately, I've built the ax-fx larger than my little lathe can spin it, so I'm going to have to guess on the coils, since I can't do a test coil. I have a pretty good idea from past uses of this same magnet as to how to wind things. Again, this off-the-shelf ax-fx is a TOY; all I'm shooting for is about 14 or 15 volts and maybe 20 amps max. All I want it for is to be an easy build for newbies who want to build something that works to charge a 12-volt battery without having to invest in a full machine shop. It should be doable with some hand tools and a drill press. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| ol_jon Newbie Joined: 19/10/2011 Location: United StatesPosts: 3 |
shoulda had this link in my 1st post:http://www.youtube.com/watch?v=YMK_nyLJNrE&feature=play er_ (hope this cut and past works) without a different tower location and more even wind conditions there is no choice for me but a vawt...my av.wind speed is low BUT we get one or two 40+ blasts each year. at present i intend on using an old 9/12 diskbrake rotor that i built some yrs ago. my goal is to be able,with a vawt type unit, to charge a small battery bank with the best overall efficiency i can manage ( no machine shop and not much in test equipment ) wedge mags (windstuff) coils@42turns 2inhand#17 wire....it was built to test the possibility of making a stator that would allow for switching the individual coils from a series to parallel winding internally,ie 84turns series for low winds and startup & 42turns two in hand for higher winds....right now it is simply the 42t 2inhand machine...i simply am/was/ unable to get it work right, too complicated (lack of talent, probably) I found that miller thing an interesting read, for sure. I will be eagerly looking foreward to that new simple vawt too! i am familiar with the Lenz unit even have scaled plans for it....don't have the right (scrap) material at this point in time...the Sandia Sav i could build on a modest scale; will,i think lend itself to modular construction (still at the doodling stage) i have the winter to put together the bits i need, just gotta settle down on what is most apt to work thanks to all who replied to my origional post ol_jon |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
ol_jon I viewed the video; thanks. Two things all three VAWT designs have in common are their large mass and their bearing support. I thought it a bit humorous that a driven HAWT (electric fan) was driving all three of the VAWTs.
The simple design I came up with puts the entire "blade" outboard of two bearings designed for extreme side loading and cost about $3 USD. I'm talking about a bicycle front hub here. What I do is mount the hub up the tower and couple the shaft to another, longer shaft using pillow blocks as bearing points all the way down. The coupling I've found that works best for this sort of thing is called an "interlock" and consists of two slots in separate round blocks with a pin between the two. The pin is stationary in one round block and bears on hard rubber inside the slot of the other. The portion of the bicycle hub that would normally accept spokes is screwed to the base of the windmill, since the base is immobile, which allows the shaft to spin freely within the cavity of the mill. I wish I had a picture to share; think of a shrouded fan like the little ones used on electric RC model "jet" airplanes. When I hoist the one sitting on my bench (pieces) I intend running the down-shaft inside the tower, so it is protected from weather. At the bottom, I'll extract the rotational energy using a sprocket and chain or maybe a belt (quieter) to run a very small ax-fx alternator (which I'm currently about 80% done building). I'll post both builds when I get around to finishing each (ax-fx & VAWT). . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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