The rpm it will run can be calculated using the following formula...

Windspeed x 88 / ( diameter x 3.14 ) x TSR = rpm

windspeed in mph, diameter in feet

When the unit is loaded it seems to like a TSR of around 0.8 for the best performance

Calculating output can be done with the usual formula...

.00508 x Area x windspeed^3 x efficiency ( turbine and alternator combined) = watts

again area in sq ft, windspeed in mph.   The efficiency of the blades runs in the 38-40% range, this is shaft power the alternator efficiency will determine the "overall efficiency" of the unit.

As an example your unit  4.92 diameter x 8.2 tall is about 40 sq ft so in a 20mph wind it might make in the range of 450 to 500 watts...

.00508 x 40 x 20^3 x .4 x .75 = 487 watts

It would run at a speed of around 90 rpm in that wind loaded...

20 mph x 88 / ( 4.92 x 3.14 ) x .8 = 91 rpm

The cut in speed, assuming around 6 mph the unit would be running at or around 30 rpm ( same formula with out the TSR... it will run faster wthout a load.

Not perfect but will get you in the ballpark for performance in different winds...

You didn't mention what voltage your going to use for charging, that would make a big difference on turns and wire size.

Hope that helps... when I get more time I can help a little more with all these projects going on around the world..