Feathering, I have always been taught, is the hinge that allows the pitch of the blades to be changed. I only know (or I should think know) of the kman helicopters that do not have a feathering hinge. I believe they change the attitude of the helicopter by the "trim tab" on the blade as it is controlled by the pilot like an airleron. If I'm wrong (great great possibility) please tell me. Also is the kman heads not known as fully articulated, semi rigid, or rigid and if not what is it called?