So You Want To Build A Wind Generator? Mick Sagrillo There seems to be a renewed interest in wind energy. The last few years have brought increasing numbers of inquiries by do-it-yourselfers about the availability of plans for building wind generators. Whenever anyone asks about building a machine, my usual advice is to buy a new one. Too expensive for a limited budget? Then buy a used unit and rebuild it. Some Wind-system Basics Normally, I try to discourage folks from building their own wind generator from scratch. My reasoning? The failure rate of home-built wind systems is extraordinarily high. The principle reason for these failures is a lack of understanding of the two major laws of physics concerning wind power. In simple terms, the first law states that the power available in the wind is proportional to the cube of the wind speed. This means that if the wind speed doubles, say from 5 to 10 miles per hour, the power available at the wind generator blades increases by a factor of eight! Even small increases in wind speed yield major gains in power. An increase in wind speed from 10 to 11 miles per hour results in a 33% increase in the power of the wind. The second law states that the power available to the blades is proportional to the square of the diameter of the rotor. In other words, if you double the diameter of the rotor by making the blades twice as long, you increase the power by a factor of four. Many folks think, "As long as I'm building by own blades, why not make them twice as long as I think I need them?" You will get more power when the wind is blowing lightly, but unless everything in the windmachine is designed to support the larger blades, it will be destroyed by the first violent windstorm. The purpose of this discussion is to warn the prudent to err on the side of caution. We all know what happens to weak links. Something flimsy or underbuilt will probably be the downfall of the project. Remember that you are dealing with machinery that may weigh as much as an automobile engine, mounted high in the air, with extremities that are rotating at several hundred rpm. Generally speaking, it can be said that the more advanced the design, the longer the components will last. "Advanced" does not mean complicated. (Remember the KISS rule: "keep it simple, stupid".) The wind systems that have lasted through the decades almost always have simple designs. Stay away from complex electronics, hydraulics, and mechanical systems on the tower. While lots of levers and springs and gizmos may look neat, they will consistently come back to haunt you. Wind-system Plans These plans for wind systems have been gleaned from the hundreds of designs published over the last six decades. Only the best, most workable designs, and only those plans that are still readily available to the public are listed. The plans are categorized in three classes based on the following criteria: Beginner: relatively simple designs that can be fabricated with the use of hand tools. Intermediate: more complicated designs that require the use of such tools as a drill press, band saw, sheet metal brake, or welder. Advanced: the most sophisticated designs requiring skilled use of such machine tools as a metal lathe or milling machine. The "intermediate" and "advanced" projects listed are, for the most part, tried and true designs with the bugs worked out of them. Those categorized as "beginner" may need some modifications and refinement. While it is unlikely that your local library will have many of the books or periodicals listed below, a good library should be able to get them for you through their interlibrary loan program. Be sure to give the library all of the information listed. Beginner Home Six-Volt Wind-Electric Plans, by H.F. McColly and Foster Buck, published by the North Dakota Agricultural College Extension Service, Fargo, ND, January, 1939. Reprinted by the Mother Earth News in 1975 as Stock #81005. This 19 page booklet describes a very simple direct-drive design that can use any automotive generator, not just 6 volt, for generating up to several hundred watts. Included is a section for carving a 5' wooden blade. Wind and Windspinners, by Michael Hackleman, Peace Press, 1974. This classic walks you through the design and construction of a Sovonious rotor coupled to an automotive alternator. S-rotors are low-speed drag devices more suited to pumping water. They are low tech and easily fabricated. Good beginner projects for low budget, low wattage applications. "Recycled Wind Generator", Energy Primer, by the Portola Institute, 1974 (ISBN #00-914774-00-x), pages 86 and 87. This article details the building of a tilt-up, 300 watt generator similar in design to the old Parris-Dunn machines (now used by Southwest Windpower in their Windseeker II). Included is information on rewinding the automotive generator for slow speed. No details on blade construction. "Transformation of an 1880's Wind Pump to a Wind Generator at King School", by John McGeorge, Alternate Sources of Energy Magazine, #24, 1976 (ISBN #0-917328-14-0), pages 18-22. A simple design using an automotive alternator. Details included for carving a good 10', 3-blade rotor from wood. "The Flight of the 'Red Baron'", Mother Earth News, #92, March/April, 1985, pages 96-102. Very low-tech sailwing type of wind generator using plumbing fittings for the mainframe and fabric for the "blades". Output is about 70 watts. "The Blue Max: Affordable Wind", Mother Earth News, #93, May/June, 1985, pages 100-105; with an update in MEN, #94, page 101. The second generation of the "Red Baron", and considerably larger at 350 watts. Like its predecessor, the "Blue Max" is also constructed of pipe fittings and fabric. "The Wind Blows Free", by John McGeorge, John's Workshop, Alternate Sources of Energy Magazine, #43, May/June, 1980 (ISBN #0-917328-33-7), pages 34-38; with an update in ASE, #47, January/February, 1981 (ISBN #0-917328-37-x), page 53. Construction of a complete micro-wind system using a 3 watt bicycle generator and a model airplane prop. Schematics for a voltage doubling control panel are included. This is for the tinkerer with very modest needs. Three others should be mentioned. While not complete plans, there is enough information in the citations for the clever person to work with. "Build Your Own Budget Windcharger", by Harry Kolbe, Mechanix Illustrated, February, 1978, pages 56-60. Diagrams illustrate the basics for building a downwind sailwing generator using an automotive alternator with step up sprockets and chains. "Here's How I Built A Wind Generator", by Winnie Red Rocker, Handbook Of Homemade Power, published by Mother Earth News, 1974, pages 198-203. This same article was also published under the title "Build A Wind Generator", in Alternative Sources of Energy -Book One, edited by Sandy Eccli, 1974 (ISBN #0-8164- 9247-6), pages 70-71. Describes a system using an automotive generator, with tips on constructing a 7' wooden blade. "I Built A Wind Charger For $400", by Jim Sencenbaugh, Handbook Of Homemade Power, published by The Mother Earth News, 1974, pages 186-197. Also published under the same title in Mother Earth News, #20, March, 1973, pages 32-36. Still another plan using chains, sprockets, and an automotive alternator. Intermediate "Do-It-Yourself Wind Generators", by Jim DeKorne, Producing Your Own Power, Rodale Press, 1974 (ISBN #0-87857-088-8), pages 43-60. While not complete plans, this excellent article describes a copy of the old Jacobs Twin Motor, a wind generator utilizing two aircraft generators, to produce up to 4800 watts. Contains a lot of good tips, and a few details on rotor construction. Design and Construction of a Propeller Type Wind Electric Generator, by Jack N. Krueger, Bulletin #76-01-EE- 02, The Engineering Experiment Station, University of North Dakota, Grand Forks, ND, January, 1976. This 61 page bulletin walks you through the construction of up to a 3kw wind generator. Included is a section on building fiberglass-coated wooden blades. "The Noble Windgenerator" by Haven Nobel, Alternate Sources of Energy Magazine, #24, 1976 (ISBN #0- 917328-14-0), pages 4-10. Very good plans for a timing belt driven automotive alternator. Construction techniques for fiberglass-over-foam blades, details for a governor, and data on rewinding an alternator for 120 VDC. Plans for Construction of a Small Wind-Electric Plant for Oklahoma Farms (Publication #33), by Arnold Benson, Oklahoma Agricultural and Mechanical College, Stillwater OK; June, 1937. This 34 page bulletin contains details for rewinding small generators, and a good section on blade building including an excellent set of blade templates. Portions of this bulletin were reprinted in Wind Power Digest, #4, March, 1976, pages 42-55, under the title "A Small Wind-Electric Plant", by the same author. "A 1000 Watt Windplant You Can Build", by John Shelley, Wind Power Digest, #16, Summer, 1979, pages 38-49. Another gear driven automotive alternator. Contains details for a governor and unique set of sheet metal blades. The LeJay Manual, by Lawrence D. Leach, copyright 1945 by LeJay Mfg. Co. This 32 page book belongs on every tinkerers bookshelf. It has recently been republished by Lindsey Publications, P.O. Box 12, Bradley, IL, 660915-0012, and is available for $6.70, postpaid. Included in the many projects are several small wind generators, generator rewinding data, and the wooden blade plans that most of the above citations employ. High-Speed Windgenerator Propeller Plans, by Kucharik Wind Electric, copyright 1980. Available from American Performance Products, P.O. Box 1351, Island Heights, NJ, 08732-1351. Details the construction of a workable 2-blade airfoil for wind generators. While Kucharik Wind Electric is out of business, Jim Kucharik has agreed to make the plans available for $12, postpaid. Advanced Building 3-Phase Alternators From 3-Phase AC Motors, copyright 1977 by Norbert Klemp. Seven intense pages of data describing how to rewind an ordinary 3-phase motor into a permanent magnet, direct-drive, slow speed alternator for wind applications. Available for $15, postpaid, from Norb Klemp, 4806 W. Cedar Creek Rd., Grafton, WI, 53024. "Concentrated Alternator Design", by Edwin R. Fitzpatrick, Alternate Sources of Energy Magazine, #38, July/August, 1979 (ISBN #0-917328-28-0), pages 18-19. Enough information is available in this short article to rewind a 3-phase AC motor to a wire-wound field, direct drive, slow speed DC generator. All of the following plans are well drawn sets of blueprints that any machinist should be able to follow. Postpaid prices are listed in parenthesis. Available from Tom Hill, RD #3, Box 806, Boyertown, PA, 19512. Plans To Build Your Own 3 Bladed, Blade Activated Governor, 13'8" Diameter Rotor ($8.00). Plans To Build Your Own 2 Bladed, Blade Activated Governor, 13'8" Diameter Rotor ($8.00). Plans To Build Your Own 2 Bladed, Blade Activated Governor, 9' Maximum Diameter Rotor ($8.00). Plans To Build Your Own 6'6" Jacobs Type Blades for the Blade Activated Governor ($4.00). Access Any feedback is appreciated. If anyone knows of any other notable designs, send the details to "Letters to Home Power". Mick Sagrillo, Lake Michigan Wind & Sun, 3971 E Bluebird RD., Forestville, WI 54213 ¥ 414-837-2267.