If each phase is 7.7 ohms, then if it is connected in delta shouldn't the source resistance be 7.7 / 3 = 2.5 ohms?
If the source is 2.5 ohms, then your machine is running at 95% efficiency, now that's impressive.
Cogging torque seems too high for a 2-bladed machine, hopefully 3 blades should be ok
5 blades would be even better,
how many blades to u plan on using?
I recommend for 18-20' blades you make them using fibreglass and carbon fibre, my 10kw blades are lager than Dans latest turbine, and are very very light and strong, i think wood is good for smaller turbines because of the weight problem.
The metal skeleton has no strength, it is strong enough to hold the foam in place,
the strength comes from the fibreglass and carbon fibre, make sure you use plenty of fibreglass at the root and fibreglass all blades together to make 1-piece, you dont want these one of these huge blade coming loose and flying off.
I haven't put the blades up yet, i haven't had time to finish the tower, been too busy with the 1.8 metre turbine and a new much larger turbine,
as for strength, the 1.8 metre is still holding together even after it hit the heavy copper power cord at 2365RPM, carbon fibre with vinyl ester resin makes very tough blades.
Michael.