It seems to be a common misconseption in these
forums about Ground Effect.
There is TWO TYPES of ground effect that
work on fixed wing aircraft!!!!
People seem to mix them up and think there is only one
1. Span Dominated GE This starts at about 1,0+ span altitude (not 0,5).
Due to less vortex buildup, we get DRAG REDUCTION Cd.
The reduction is logarithmic and is very significant close to ground (from 0,5 span and down). A high wing aircraft will not get
as much affected as a low wing.
2. Chord Dominated GE This occurs at about 1,0 chord altitude.
Due to an increase in RAM pressure below the wing,
we get an INCREASE in LIFT Cl. The peak is around 0,05-0,2 chord - depending on airfoil etc.
Soo, THIS is the effect WIG aircraft mainly use.
They usually have a long chord and short wings.
Note high tail to avoid downwash & wake from the wing, ground effect disturbances etc. The very reason for this topic...
Cheers,
M