I stand corrected, thanks. Easy to understand summary of helicopter ground effect, with pictures: http://www.copters.com/aero/ground_effect.html http://www.co

I stand corrected, thanks. Easy to understand summary of helicopter ground effect, with pictures: http://www.copters.com/aero/ground_effect.html http://www.copters.com/aero/ground_effect.html I note that the rotary wing ground effect works to a height of about the rotor diameter, so it's not clear to me that this is a useful effect with these small rotors.