A vortex ring state is when the helicopter’s downwash recirculates into the induced flow and the helicopter descends while under power.
Loss of tail rotor effectiveness, commonly referred to as LTE, is when the ability to provide anti-torque thrust from the tail rotor is ineffective or highly unreliable.
More power is required for left pedal turns. If a left turn can be completed, there is enough power available to safely control the helicopter in the current flight conditions.
The height-velocity diagram is provided by the aircraft manufacturer and indicates speeds that should be avoided as a safe autorotation might not be possible.
Total drag is the sum of parasitic drag, profile drag, and induced drag.
When flying for range, operate the helicopter at the speed for least amount of drag.
When flying for endurance, operate the helicopter at the speed using the least amount of power.
A high-density altitude decreases helicopter performance.
The aircraft manufacturer sets the helicopter’s center of gravity limits. If operating outside of these limits, the helicopter may be uncontrollable in certain situations.
The rotor disc becomes more efficient within close proximity of the ground, so it takes less power to provide the same amount lift.