What is the main difference between “ground effect” and hover?

The distinction between ground effect and hovering lies in the dynamics of how a helicopter interacts with the air when close to the surface. Ground effect refers to the aerodynamic phenomenon where the presence of the ground alters the airflow patterns around the helicopter's rotor blades when it is very close to the surface. This change in airflow leads to an increase in lift and a reduction in induced drag, making it easier for the helicopter to maintain altitude when in this state.

When a helicopter hovers within ground effect, it achieves increased lift because the rotor system does not have to displace as much air to generate the necessary lift to overcome its weight. This enhanced performance allows for more efficient hovering, which can be particularly beneficial during takeoff and landing phases.

This understanding emphasizes that while hovering is a state of maintaining a position in the air, ground effect is a specific condition that influences how efficiently a helicopter can hover close to the ground. Therefore, while both terms relate to a helicopter's ability to remain stationary in the air, ground effect specifically enhances lift and reduces drag when operating in proximity to the ground.