Multiple Rotors: A High Efficiency Windmill Design - Experiments Results
http://www.virtualsciencefair.org/20...tml/index.html
" The results show that multiple rotors operated at lower wind speeds and had a higher conversion efficiency "
"Adding a second rotor produced the largest increase (over 2000 %) in electricity generated. "
"My results suggest that the overall efficiency of windmills could be substantially increased through the addition of a second rotor."
"My engineering objectives were to design and build a multiple rotor, horizontal axis, laboratory scale windmill that could be coupled to the axle of various sizes of DC motors. The scale model was used to determine the effect of different rotor attributes (number, size, distance apart and orientation of the rotors) and size of DC motor on the resulting mAmps and mVolts generated. The rotor arrangement and motor that produced the most electrical energy output was identified. "