Helicopters, unlike fixed wing aircraft, can hover; that is to say, they can remain in one position without moving forward of backward, or side to side. In order to do this, the helicopter pilot has to make sure that four factors are considered: the lift, the weight, the thrust, and the drag. Many pilots believe hovering is the most challenging part of flying a helicopter, and yet the basics are simple.
The helicopter has a weight. For out purposes, lets say that this is 8,000 pounds. In order to counter the effects of gravity, the amount of lift that the rotor and aircraft generates has to be almost equal to 8,000. A pound or two isn’t going to make a noticeable difference, but several hundred pounds will. Additionally, the helicopter generates its own wind (from the rotating blades) while in a hover, and the pilot has to counter these as well to successfully hover.
The pilot must provide enough trust (forward motion) to counter any wind currents and drag that are acting on the helicopter, and they must be able to counter any tail rotor thrust that the aircraft generates itself. The power has to be enough to turn the tail and main rotors, and overcome the inherent drag that the aircraft produces.
While in a hover, the amount of thrust that the main rotor generates can be changed to maintain or alter the hovering altitude. In order to do this, you change the pitch of the blades themselves, which changes the drag on the rotors, and simultaneously the engine power must increase to keep the main rotor speed constant (more power is needed to overcome the drag created by the steeper blade angle).
The ability of a helicopter to successfully hover is generally linked to its pilots abilities; although all helicopters are capable of hovering, not all pilots are capable of executing a successful hover. This is the difference between helicopter pilots and plane pilots. Hovering is among the unique capabilities of a helicopter that sets it apart from fixed wing airplanes. All pilots should aspire to being able to execute a successful hover.
And don’t forget, the only time a fixed wing aircraft matches a helicopter ability to remain stationary on the horizontal and vertical axis , is on the ground! If a fixed wing plane attempts this in the air, I certainly wouldn’t want to be in it!