Wind turbine mast construction

 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

  You will need guy line support for such thin masts. The side
pressurtes can be calculatd by the amount of electrical energy it
produces and the efficiencies. I have wanted to but never delved into
this calculation for mine. Daestrom has this info well polished, I
think.

 On Tue, 20 Feb 2007 14:42:31 -0800, 'Captain' Kirk DeHaan


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

 wmbjk said the following on 2/20/2007 4:43 PM:

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

 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.