Living with partial blade stall of rotors and propellers does not only reduce efficiency of generating thrust. In the case of tiltrotors it can ruin aircraft stability. Two GIFs below show schematic interpretation of the formation of blade stall: Scenario No.1. Fixed pitch propeller. Changing axial speed of a working propeller causes a serial transformation … Continue reading  Twisting Vector Field of Airflow Calls for Variable Blade Twist of Rotors & Propellers