RVR800
You said the acceleration due to gravity is a constant on earth, how does "on" Earth relate to flying? PS I don't think it is constant at 9.81 m/s/s anyway, the Earth is not a perfect sphere and at the Equator there is more mass 'underneath' the body whereas at either pole the mass of the Earth is more spread out sideways than straight 'down'.
New Bloke
Only PART of the total lift from an aerofoil is generated by the pressure distribution. Some of it also comes from the coanda effect, ie throwing air down by curving the top part of the aerofoil produces an equal+opposite reaction of throwing the aerofoil up. Think of a propellor (another aerofoil) - are you saying that standing behind the propellor there should be no propwash because "it's only the pressure distribution" that causes thrust from this propellor?
And can you explain a bit more about the glide bit?
And the last point for everyone who thinks ground effect makes a difference - I don't because it's ALL THE SAME AIR. Doesn't matter how far away from the floor it is, the downforce is still acting on the air from the geese wings. Maybe it's spread out, maybe it's not. Ground effect WOULD be significant if the 'system' i.e. the aeroplane cargo hold was open.
This is interesting! Certainly makes people careful with the words they choose.