Crab,
We are getting somewhere. If the pressure below the wing/rotor in the IGE case is the same as the pressure beneath the wing/rotor in the OGE case, tell me again how the pressure against the ground has an effect?
Of course pressure is part of the flow equation, but the issue I am countering here is the assertion that the ground somehow allows pressure to build up (a ground cushion).
In fact the pressure must be equal in both cases, else the aircraft would rise in the IGE case.
Proof:
Set Baro altimeter to zero while flat pitch, lift to hover, read altimeter. If pressure is higher below rotor, altimeter would show altitude drop (higher pressure). Does it?