As volume of upflow increases, the blades begin to stall (airflow separation) near the hub and a second set of vortices, similar to the rotor tip vortices, then form in the center of rotor system.
The blades begin to stall (airflow separation) near the hub. This is as volume of upflow increases. This is then. The blades begin to stall (airflow separation) near a second set of vortices. This is as volume of upflow increases. This is then. Vortices are similar to the rotor tip vortices form in the center of rotor system.