:t Systems gal force on the blades. The author suggests this control system not be used. Otherwise, the author felt that the system operated well in a down-wind mode. His slip ring system would be easy to duplicate and would probably serve quite well. The third system in the magazine is actually a modification of an old water pumper with the blade replaced by a high speed air foil. The system operates as an upwind horizontal axis generator with a hinged tail vane control system and has a toothed belt drive system. The design is quite good in concept, but the execution is a little shaky. Too much wood, radiator clamps, and U-bolts are substituted for quality hardware. The machine also suffered from the unfortunate error of having the prop mounted backwards. For some reason, home builders often make this mistake. On a Clark-Y air foil such as the machine in this article uses, the flat side of the blade faces the wind, not the curved side. One of the best sets of plans available appears in Technician's and Experimenter's Guide to Using Sun, Wind, and Water Power, by Richard E. Pierson. This generator was designed by Bob Landing of Pleasant Hill, California. Landing's system utilizes a gravity activated tail vane deflection control system on a three-bladed horizontal generator. Gearing is achieved with a home-made gearbox. The method of carving the prop is quite simple. The resulting air foil is rather inefficient, but doesn't compromise the system's performance too greatly. These plans include a complete parts list. One questionable element in the design is the use of wood members in the transmission housing. July 1981 RAIN Page 13 Flannagan's Plans (Box 891, Cathedral Station, New York NY 10025) sells a set of plans based on the Princeton Sailwing for $45.00. The sailwing develops one kilowatt of power at the shaft in a 20 mph wind. The rotor measures 11 feet across. The primary advantage to the sailwing concept is ease of constuction. The air foil changes shape and aerodynamic performance as the speed of the wind varies, creating a self-government effect. These plans do not contain any information on generator selection or gearing systems, hence, the builder must make these design choices based on shaft power and rpm at the chosen design speed. The use of pop rivets for fastening is not a good idea here, by the way. One of the worst sets of plans available is in a book that was recently offered in a TV ad campaign. The machine featured in this book is an exercise in unnecessary complexity. It is a downwind three blade system. The entire generator housing is made out of wood. Blade construction is unnecessarily complex. Worst, the batteries are (for some unknown reason) located at the top of the tower. There are quite a few other sets of plans and even a few kits available, all probably worth examining, but only if approached with a critical eye. So, do some homework, evaluate your electric requirements, assess your wind resource, and design a system that is appropriate. Build it from carefully selected parts, all matched to the task they are asked to perform. It might even be possible to put together a system that delivers power at under 2 cents a kilowatt, a feat no utility company will ever match in a future of energy scarcity. OD Micheal Nelson is the director of North East Washington Appropriate and Creative Technologies (NEW ACT), a non-profit research group developing renewable energy options for rural Eastern Washington. He can be contacted at P.O. Box 385, Republic, WA 99166.
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