[MLB-WIRELESS] wind power

[Tim Hogard]

One thing to consider if your building your own wind power solution
is that the wind speed will get very high at some point and when
that happens, will your home built turbine self distruct?  If it does,
where do the parts go and how fast will they be moving?

To put it in perspective: A Cessna 150 prop has two blades about a
meter long.  Its max speed is about 3500 rpm.  Thats the speed where
the forces on the bade cause it to deform and the tips will be close
to supersonic.  Thats on a custom desinged bit of metal that will
cost about $12k new and is expected to last about 3000 hours or 5
years.  It is not trivial to build a blade that can spin very fast
and the rotation speed is directly related to the wind speed. 

The max design speed for a wind turbine will need to be in the range
of 180 km/hr.  If your going to get it spinning fast enough to
provide power at the 20 km/hr your going to get most of the time
if your luck.  The speed at the Essenden Apt right now is gusts to
52km.  A you want it to spin not faster than maybe 50 rpm at 50
km/hr but that means it will spin at 5 rpm at 5km/hr which isn't
fast enough for an alternator unless you do a bit of work on it.

If you look at the typical water pump windmils used on farms, you
will see they have a blade that forces the blade to turn 90 degrees
into the wind if the speed gets too high.  They also have locks so
when the speed gets too high, they lock down.

Its tricky to deal with the high wind situation right but you need
to give it consideration if your going to do this.

-tim
http://web.abnormal.com

> 
> I saw the design of an alternator version in a book I picked up from either
> ...

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