Kolibri had a single rotor blade???
I wouldn't normally dream of questioning Nick Lappos but all the pics I can find of the NHI H3 clearly show a conventional two-blade configuration.
I do recall a single blade helo from the '50s, with a 'cannonball' counterbalancing the blade. A Bolkow?
Edit: to point out that although it's stated the NH17 and the Kolibrie had "no torque and so no anti torque devices" they both had tail rotors as bearing friction is a factor in the hover and exerts a significant torque reaction to the fuselage and has to be countered, as we know from t/r drive failure practice.
I notice that the Kolibrie had a single-bladed tail rotor which is perhaps where the confusion arose.
The single bladed helo was the Bolkow 103.
Last edited by meleagertoo; 12th July 2021 at 12:39.