Helicopter automatic flight control system
You could think that the helicopter is now stably hovering. Because the tail rotor now produces a greater sideway thrust, the lateral dislocation of the helicopter is increased, which needs to be adjusted for via the cyclic. Thereby the helicopter begins to rotate along the yaw axis, which needs to be adjusted for via the tail rotor. This causes the torque to increase, due to the wider angle of attack of the rotor blades (and thus greater air resistance). As we have seen, the pilot has to pull the collective upwards when he wants to ascend during hovering. When the pilot operates one of the flight control elements he always needs to adjust the other two. Correspondingly the angle of incidence is decreased when the pilot pushes the collective downwards (Fig 2). Thus the total lift increases und the helicopter begins to ascend. When the pilot pulls the collective upwards, the angle of incidence (and thereby the angles of attack) of all rotor blades is increased by the same amount. This means that by adjusting the angle of incidence with the flight control elements the angle of attack, and thus the lift, changes as well. The angle of attack on the other hand is the angle between the rotor blade profile and the oncoming airflow.
![helicopter automatic flight control system helicopter automatic flight control system](https://vtol.org/images/thumbs/previews/53_2_10_Vidal_page_1.jpg)
The angle of incidence is the angle between a defined axis along the helicopter and the position of the rotor blade profile. With the flight control elements (cyclic, collective and pedals), the angle of incidence at the main rotor resp. Because of a helicopter’s instability the cyclic must never be released during flight unless the helicopter is equipped with an automatic stabilization system. The feet are used to operate the tail rotor with the pedals. In every helicopter the cyclic is operated with the right hand and the collective with the left.