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-   -   Wind Generator Shakes Boat (http://www.sailnet.com/forums/electrical-systems/78268-wind-generator-shakes-boat.html)

DocBrauer 09-03-2011 04:53 AM

Wind Generator Shakes Boat
 
I am a solo long distance sailor who crossed Pacific last year currently in Fiji. I have an older Air-X that worked fine until I bought Silentwind blades for it. With the new blades generator tower shakes even at low wind speeds. Looked at the hub and noticed where previous owner may have added 2 globs of molten metal, assume for balancing like you would a tire. Purchased a new hub for Silentwind blades and still seeing shaking. With old blades and old hub I have no problem but would like to use new blades. No help from Silentwind company and Air-x manufacturer famous for no help. Assume I need to balance and my memory says use screws and washers but don't know how. Possibly find a tire shop here and have it balanced? Internal adjustment in Air-X? Any help appreciated.

imagine2frolic 09-03-2011 06:15 AM

Take the hub, and blades off. Put them on a spindle, and see which blade falls to the bottom. Kiss using a weighted tape for making this adjustment. Check out s/v hotwire as a distributor in Fl. for the tape......i2f

DocBrauer 09-03-2011 07:14 AM

tape
 
Ok, I guess the weight would go directly 180 degrees (directly up) opposite to whatever area of hub is down. I waited 3 weeks here in Fiji for the new hub and from here heading Vanuatu, Solomon Islands, Palau, then Philippines where I promised to do some volunteer work. Too far to go to be waiting for tape. I'll have to figure something else out to use as weight, and how much to use.

imagine2frolic 09-03-2011 11:03 AM

When you get to the Phils. Be sure to try some JBC, or Durianworld candies. In Manila, and Davao they can easily be found in the SM malls. Yummy little aphrodisiacs:D.......i2f

PorFin 09-03-2011 11:14 AM

Doc,

Here's a suggestion for a temporary fix. I've never tried it, but in principle it should work.

As I2F suggested, the lead tape is the easiest solution. You adhere strips to each blade, and then cut off small sections until the blade is perfectly balanced. The tape is thin, and doesn't significantly disturb the airflow over the blades. Lead tape is not that difficult to come by normally, but since you're in Oceania I can't imagine what a challenge it may be trying to find it.

So the expedient solution is to take your old hub, and start balancing it with the new blades installed. It will be tedious, but start with equal weight pieces of lead taped to the hub between the blades. From this point, follow the procedure recommended for the KISS generator -- except that you'll be decreasing the size of the hub-mounted weight instead of the blade-mounted tape. Since the position of the weights are closer to the center, they will be less sensitive to adjustment than tape would be further out along the arm of the fulcrum (i.e., out on the blades themselves.)

Once you've achieved balance, carefully mark EXACTLY where the weights are on the hub and then epoxy or polysulfide the weights to the hub. This should work, but for extra credit (and peace of mind) continue...

Obviously, you're trying to keep the wieghts as small as possible to minimize the risk of these puppies coming loose when the blade's spinning. While centrifugal forces will be less prevalent closer to the hub, they will exist.

After you've found balance you could then carefully remove and measure the individual weight of each piece of lead and tape to determine what your differential is at each point on the hub. You'll wind up with two numbers that are not zero -- this will be the mass of the wieghts you'll need to make and adhere to the hub.

imagine2frolic 09-03-2011 11:22 AM

Live in the Philippines

Go to this site, and at the top. You can find John Meile. He is a rep for the West System, and numerous other nautical products. He may be able to help you find the tape?.......i2f

PorFin 09-03-2011 11:23 AM

Doc,

Meant to mention this earlier -- lead tape is often used to add weight to the head of golf clubs. I don't know if there are any golf courses or golf pro shops in Fiji, but if there are they might be a source for lead tape locally.

Undadar 09-03-2011 11:26 AM

There are a couple ways to balance any "propellor". I used to dynamically balance aircraft propellors to nearly perfect balance with computerized equipment. It sounds like you have pretty limited resources so let's go with the easier options.

The first is to remove the hub and blades as a unit, mount them on a spindle/shaft, set both ends of that spindle on a flat surface (so the blades are vertical and can rotate), and see which blade rotates to the bottom. You then add/subtract weight from the lightest/heaviest blade). I'm not sure this is possible with any of the wind turbines (not sure how the hub mounts to the unit).

The second is to remove each of the blades and then match all of them so they weigh exactly the same amount AND the weight is distributed evenly. That involves weighing the hub end of each blade and adjusting til they all match and also weighing the tip end and adjusting til they all match (like connecting rods on an engine).

There are some other factors (like blade tracking and even pitch) but I would start with matching the weight of all the blades.

The "type" of weight you use isn't terribly important. "Heavy" tape, lead tape, lead stick on weights, spray paint, etc... all work. Once you get it balanced note where the added weight is and how much and then afix the weight permanently. A taped on penny is great for the initial effort but won't last very long in normal operation.

JdFinley.com | Sailing, development, and life with JD
You can observe a lot just by watching.

DocBrauer 09-03-2011 02:22 PM

I2c, Porfin, Undadar thanks for advice. I tried durian once and it's got to be the nastiest fruit in the world but will dare the candy. I'm a little leary about adding anything to the blades not only because silentwind in instructions says don't do that but also weight had been added to old hub and it worked with old blades. Now it seems easier to add small weights then to try and add lots of little weights then remove and my mind still says screws/bolts and washers from reading somewhere in past. Here is my plan unless someone says Doc that's stupid (wouldn't be first time). Find area that needs weight and drill small hole and add small bolt and different size/quantities washers close to outer circumference of hub until when both heavy side and bolt are held in level horizontal position then released there is no rotation. Spin again to see if is still heavy side and repeat. Do until blades stop randomly. What do you think? Do know of a golf course near Denerau I could look for tape if necessary.

imagine2frolic 09-03-2011 03:04 PM

Smell like hell, and taste like heaven is what they say about durian:eek:. The candy is sweet like any other candy. I found the first couple just plain different. Eventually I was eating several at a time. They come in sticky portions, tiny pies, and in different flavors beside durian.

Some good old duct tape may be heavy enough to do the job. Bolts, and screws may have a tendency to become projectiles if they come loose. BEST WISHES in figuring it out successfully.

I've been working my way too the Phils for a couple of years now via S.F. Ca. Eventually I will get there. I love the diversity of weather, and geography. Not to mention a chance to sail there........i2f


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