An Affordable Wind Generator You Can Make Yourself: The Blue Max
(Page 2 of 4)
May/June 1985
By the Mother Earth News editors
Equally critical is the placement of the hub components; not only does this affect the balance of the finished rotor, but it also determines the accuracy and ultimate effectiveness of the blade pitch mechanism. The shaft housings must be perpendicular to the hub walls and an equal distance from the hub plate and mount. Likewise, the pitch stop brackets need to be positioned, as indicated, 40 degrees counterclockwise in relation to the housings when the hub is viewed from the rear.
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While we're on the subject of blade pitch, it's important that you accurately duplicate the angles recommended in the blade frame detail. Note that the shaft retainer arms are set parallel with the frame mounts . . . and fixed there with machine bolts and 1/8"-rod locating pins. Also, don't ignore the fact that the blade tips lie forward of the frames by 11 degrees.
The plastic-pipe governor switch housings are held in place with hose clamps and can be locked at any point along the jackshaft output sheave spokes. The farther they are from the pulley hub, the sooner they'll activate the solenoid that engages the alternator's field windings. The slip ring hub — a bushing that's simply turned from a chunk of Delrin (but which could just as easily be molded from phenolic resin or any other nonconductive material) — is pinned to that jackshaft pulley and jacketed with a small section of 1-1/2" copper pipe heated and quench-fitted in place.
Unlike many other sail-wing wind machines, ours doesn't use a taut woven fabric. Though a nylon or sealed canvas could serve as an effective skin, we opted to keep initial costs down by utilizing polyethylene tarp material on the blades and tail. (Admittedly, it will probably need to be replaced periodically, depending upon local weather conditions.) Don't waste time trying to stretch the fabric tightly over the frames. It's better to just firm it up and concentrate on double-stitching the folded-over seams on the tail and the leading seams on the blades (the latter will ultimately be hidden when the sleeves are turned inside out and fastened between the framemount clamps).
As was the case with our trainer windplant, the Blue Max should be mounted on a tower 20 or more feet above any obstructions and several hundred feet away from them. Since the alternator produces a maximum of 25 amps or so at a regulated 13.8 volts, a bank of automotive batteries — using a circuit wired as shown in our diagram — should make an ideal storage system. (If you're interested in monitoring wind direction and velocity before building your plant, you might consider assembling the inexpensive weather station featured in MOTHER NO. 68, page 176.)
