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Posted by Solar Flare on February 20, 2007, 10:23 pm
Please log in for more thread options It is not the balance that is the problem. It is the side force. A
windsock does not have even the same magnitude of side pressuref from
the wind that a wind turbine does. I suspect you will end up with a
damaged bent mast when you are done with those lighter pipes.
Wayne will know about socks though.
> wmbjk said the following on 2/20/2007 4:43 PM:
>> On Tue, 20 Feb 2007 14:42:31 -0800, 'Captain' Kirk DeHaan
>>
>>> I have an Air 303 wind turbine. Still working fine. My issue is
>>> it is not high enough. It's only 15' off the ground although we
>>> are a few hundred feet off the valley floor on the side of a
>>> mountain and have decent wind flow. The actual "good" wind stream
>>> is about 15' higher. I plan to build a single pole tower of
>>> nested/stacked sched 40 steel pipe with a pivot arrangement at the
>>> bottom. The bottom will start at 3" and end up at the required 1.5
>>> inch pipe. 3 to 2.5 to 2 to 1.5. I am looking for information on
>>> lateral forces I may encounter so I make sure I have enough
>>> concrete at the bottom and a stiff enough pole that will hold up
>>> to the gusts. My current thinking is a 15' section of sched 40
>>> 1.5 inch as the last step with the remaining steps in 5' sections.
>>> Overlaps at the welds will be 1.5 feet. I'm looking at about 800
>>> lbs of concrete for the base set 5 feet deep. I have a C band
>>> satellite dish that has not moved in 12 years with this amount of
>>> weight at the base and a huge surface area even though it is mesh.
>>> Do you have any pointers to tech/engineering data that might help
>>> and what do you think of the plan?
>>>
>>> Any help appreciated
>>>
>>> Kirk
>>
>> A 303 is a pretty light load, I've seen quite a few on un-guyed
>> towers
>> of 20 -30', most of lighter construction than you have in mind.
>> Your
>> plan sounds fine to me, although I'd probably simplify it with
>> fewer
>> steps in the pole. I posted some info previously that might give
>> you
>> an additional data point - "Here's a photo of a similarly
>> constructed
>> windsock tower.
>> http://citlink.net/~wmbjk/images/windsock.JPG Sock is 18"X96", pole
>> is
>> close to 30' tall. It only bends a little in a stiff wind. The
>> brace
>> at the bottom doesn't hold anything up, it's attached to a
>> counterweight so that I can raise and lower the pole by myself.
>> Concrete is about 18" in diameter, 36" deep. I dug most of the hole
>> using a powered chisel, which should give you some idea of the
>> ground
>> hardness."
>>
>> Wayne
>
> Hadn't thought of a counter weight. Using that my plan should work
> fine with some changes in the steps. I'll stick with the overkill
> on the concrete since we have some wet spring thaws. Thanks!
>
> Kirk
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