Ground effect

Definitions

• A usually beneficial influence on helicopter performance that occurs while flying close to the ground. It results from a reduction in upwash, downwash, and bladetip vortices, which provide a corresponding decrease in induced drag.
• A condition of improved performance encountered when an airfoil is operating very close to the ground. When an airfoil is under the influence of ground effect, there is a reduction in upwash, downwash, and wingtip vortices. As a result of the reduced wingtip vortices, induced drag is reduced.
• A usually beneficial influence on rotorcraft performance that occurs while flying close to the ground. It results from a reduction in upwash, downwash, and bladetip vortices, which provide a corresponding decrease in induced drag.

References

• Helicopter Flying Handbook, Federal Aviation Administration, 2019
• Powered Parachute Flying Handbook, Federal Aviation Administration, 2007
• Rotorcraft Flying Handbook, Federal Aviation Administration, 2000
• Weight-Shift Control Aircraft Flying Handbook, Federal Aviation Administration, 2008