The Savonius Super Rotor!

Michael Hackleman introduces a very effective wind energy device made from 55 gallon drums. The Savonius or S-rotor is from California-based farm research center Earthmind, which specializes in alternative energy experiments.

| March/April 1974

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    Michael Hackleman

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We all know what wind chargers look like or do we? In this article Michael Hackleman introduces a very effective wind energy device most of us have never seen or even heard of. The Savonius or S-rotor was introduced to this country way back in 1924 but suffered stiff competition from the already perfected multi-blade farm windmill and the "more exciting" high-speed propeller-driven generator. Now Earthmind - a California farm research center that specializes in alternative energy experiments-has revived the S-rotor in a very impressive fashion. 

With the move back to the land and the homesteader's soon to be everybody's-need for a, source of energy other than Con Ed, the time has come to reconsider the generation of electricity from the wind's power and many of us are doing just that. Until now, however, only one type of wind charger has been readily available: the propeller-driven generator or alternator. (Such rigs used to be called "Stuart mills" and I've found it convenient to use the term in this article.)

The props that spin the generators on conventional wind plants vary in number of blades (two, three or four) and in the complexity of their aerodynamic surfaces. Differences notwithstanding, however, the lower end of the price range for even owner-built Stuart mills hovers stubbornly around $400 plus.

Here at Earthmind we've been trying to break through that price barrier by experimenting with a little-known alternative wind device which is low in cost, simple to construct and boasts several other distinct advantages over the Stuart mill in general performance and safety of operation. This unit is the Savonius rotor often called the S-rotor because of its appearance.

The Savonius rotor is easily made: Just split a cylinder equally through its length, offset the halves by a distance equal to the radius of the original form and secure the segments to end plates the width of the new diameter (see Figure 1 in the Image Gallery). Then insert a rod through the center of the assembly, fix its ends in bearings, and the device will rotate when exposed to the wind. If you use soft drink, beer or other small cans for your rotor, you'll have a toy but start with 55-gallon drums stacked three on end (out of phase with one another) and even at low wind speeds the power from your creation will surprise you.

You'll be even more surprised by the S-rotor's performance when it's compared to that of the Stuart mill. If both were tested in wind tunnels, the Savonius design would appear inferior but under normal outdoor conditions the results are almost reversed. To see why, you'll need some understanding of the nature of moving air masses.

B Knight
12/11/2008 9:12:20 AM

Yes, these designs have been around for a long time. Here's another link to a site with several free plans, for both a 55 gallon drum (plastic drums) wind turbine (instructional videos), more VAWT turbines and a 4 foot horizontal axis wind turbine. All plans are free. Enjoy, Bruce.

11/18/2007 11:22:50 AM

we have some free wind turbine plans on our site that can be downloaded if you are interested. they include various VAWT designs. just pop along to download them

11/17/2007 8:57:05 AM

Can I order the plans by sending a check to Earthmind at 26510 Josel Drive, Saugus California 91350 or, perhaps via this internet site? Sincerely, Bill

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