Ground Effect

Ground Effect

Ground effect is the phenomenon that occurs when an aircraft gets closer to the ground, resulting in an increase in lift and a decrease in drag. This is due to the condition of slightly increased air pressure below the wings of an airplane or the rotor system of a helicopter, which increases the amount of lift produced. The ground effect exists within approximately one wing span or one rotor diameter from the ground.

The decrease in drag is induced by a reduction in upwash, downwash, and wingtip vortices, providing a corresponding reduction in induced drag without a corresponding decrease in lift. It results from the alteration of the downwash angle due to the proximity of the ground or any other surface it is flying over.

The ground effect becomes significant within a distance of about one half of the wingspan from the surface. This is due to the reduction in the space for the airflow to be distributed between the wings and the ground surface. The airflow beneath the wing or rotor is reduced and redirected, creating a cushion of air that modifies the aerodynamic forces acting on the aircraft.

Ground effect is an important concept for pilots to understand and take into account when flying at low altitudes or during takeoff and landing. They should be aware of the effects it can have on the stability and performance of the aircraft, particularly when operating near large bodies of water or uneven terrain.