The vertical flight of a helicopter is controlled by?

The vertical flight of a helicopter is primarily controlled by collective pitch changes. The collective pitch control alters the angle of the rotor blades simultaneously, which affects the amount of lift generated by the rotor system. When the pilot increases the collective pitch, the blades have a greater angle of attack, leading to increased lift and, consequently, a climb in altitude. Conversely, decreasing the collective pitch reduces lift, allowing the helicopter to descend.

While cyclic pitch adjustments influence the helicopter's forward, backward, and lateral movement by changing the pitch of the blades dynamically as they rotate, they do not primarily control vertical ascent or descent. Tail rotor adjustments are mainly used for controlling the yaw or direction of the helicopter rather than vertical movement. Governor control regulates engine speed and maintains rotor RPM but is not directly responsible for altitude changes.

Thus, collective pitch changes are the key factor in managing a helicopter's vertical flight.