Hi Charlie,

Just in case you didn´t know, 4-blade teetering heads have been used in full size practice. Igor Bensen did and, more recently (a few years ago), my friend Angel Serrano converted his full size gyroplane by fitting a second teetering rotor on top... He slightly reduced the rotor diameter of the standard rotors. Says he obtained 15 Km/h (9 MPH) higher cruising speed. With full sized aircraft, I guess it is easier to use two teetering rotors instead of building a complicated 4-blade articulated head which might need lead-lag dampers, etc...

Regards,
Emilio Cabezas