Birdhouse, You know I just love to weld and the metal is cheeper for me then large diameter piping plus
I have put these turbines up on a deck that is high above a valley no problem with a steady breeze
the wind is funneled into the valley from the ocean and the traffic on the main road o a wind turbines dream
not to bust your steels, but, i just bought a 21' chunk of 6" pipe today from my surplus steel yard for $62.38. it will be cut in three pieces for parking lot bollards.
a 4" piece would be much cheaper. secure four guys to it, and boom, you have a *decent* tower.
if you think the wind behind your house on your deck is good, i think you are a bit misguided. i very well understand this is a hobby for you, and i'm sure you have a lot of fun with it.
the "real" wind is much higher where obstructions don't create turbulent air. even my 70' tower is far short of what i really wish it was. there are 40-50' pine trees within 150' of my tower that i'm sure reduce my turbines output to a significantly measurable degree.
i also agree with others on the tower design. there is no real reason to have horizontal members in your tower design. they should all be angled to add shear strength in all directions. just google image "antenna towers" and you'll get the idea.
enough critique. i'm sure you are having fun, and that's all that really matters... unless you live off grid and need every electron....
adam