Ground effect

Ground effect may refer to:

Ground effect (aerodynamics)

In fixed-wing aircraft, ground effect is the increased lift (force) and decreased aerodynamic drag that an aircraft's wings generate when they are close to a fixed surface. When landing, ground effect can give the pilot the feeling that the aircraft is "floating". When taking off, ground effect may temporarily reduce the stall speed. The pilot can then fly level just above the runway while the aircraft accelerates in ground effect until a safe climb speed is reached.

Principle of ground effect

When an aircraft flies at a ground level approximately at or below the length of the aircraft's wingspan or helicopter's rotor diameter, there occurs, depending on airfoil and aircraft design, an often noticeable ground effect. This is caused primarily by the ground interrupting the wingtip vortices and downwash behind the wing. When a wing is flown very close to the ground, wingtip vortices are unable to form effectively due to the obstruction of the ground. The result is lower induced drag, which increases the speed and lift of the aircraft.

Ground effect (cars)

Ground effect is a term applied to a series of aerodynamic effects used in car design, which has been exploited to create downforce, particularly in racing cars. This has been the successor to the earlier dominant aerodynamic theory of streamlining. American racing IndyCars employ ground effects in their car's engineering and designs, similarly they are also employed in other racing series' to some extent, however Formula One for example, as well as most other racing series, primarily across Europe, use design constraints due to specific regulations (or complete bans) which affects and limits its effectiveness.

Theory

In racing cars, a designer's aim is for increased downforce and grip to achieve higher cornering speeds. A substantial amount of downforce is available by understanding the ground to be part of the aerodynamic system in question, hence the name "ground effect". Starting in the mid-1960s, 'wings' were routinely used in the design of race cars to increase downforce (this is not a type of ground effect). Designers shifted their efforts at understanding air flow around the perimeter, body skirts, and undersides of the vehicle to increase downforce with less drag than compared to using a wing.