Ok so here is what i see. Your motor and turbine have huge potential but are limited by the 5v output. Can you increase this somehow?
It's a long story, but this windmill is really just a toy. The goal was never to make the maximum amount of power or energy from it. I've made about 10 windmills in the past that had nice sets of blades (hand carved, sheet metal, CNC'ed), but I've never made one that can make power in low winds (less than ~15 mph). My motor also has to spin too fast before getting to 12 volts to charge, so I've had this long standing dream to make something that could charge a lower voltage battery (a bunch of 1.2v NiMh's) and then switch the cells around to run a 12v inverter. At one point I spent a ton of time making a 3 bladed savonious vertical axis blade set, only to find that it didn't have enough torque to spin my motor. After some pondering and deciding to spend more than $10 on the project, I decided I would make a 4.2v li-ion setup since these batteries are so cheap, and I happen to have 18 of them sitting around. I since purchased another 40 cells that were 3.2 Ah each. A long time ago, I had this motor up on a pole for 18 months straight with no furling mechanism and it survived. It's only ~ 7 feet off the ground and surrounded by woods on the east and west sides. I'm in approximately a class 4 wind site if I were up above the 60' trees.
I did some more measurements today on the blades so I can do some better calculations on the forces. Center of mass of the blade is 0.355m. The mass is close to 1 kg ( a bit less actually ).
Assuming fully unloaded is TSR of 14. I have a feeling my blades are a bit chunky and won't spin as fast as some of my previous blade sets.
53.55 mph @ TSR of 14 = 3,000 RPM = 314.159 rad/s
F = ma = m* (omega^2*r)
F = 1 kg * (314.159^2*0.355) = 35,037N = 7,876.6 lbf
The blade is clamped now on two sides instead of one.
Clamp force assuming 0.15 friction coefficient = 7,876.6/(2*0.15) = 26,255 lbf
Clamp force assuming 0.2 friction coefficient = 7,876.6/(2*0.2) = 19,692 lbf
Speed corrected for 14 TSR, 30,580 lbf and 0.15 friction coefficient = 57.8 mph
Speed corrected for 14 TSR, 30,580 lbf and 0.2 friction coefficient = 66.7 mph
It seems like it would be difficult to make a windmill much larger than 7' in diameter without having an excessive amount of Cf force @ 60+ mph un-furled unless you made them out of carbon fiber. Certainly not something that you would want to risk with a real tower and something powering your house or something that would burn out your alternator.