I think some of you guys have forgotten the basic principals of flight. The upwards force of lift is generated mainly from the low pressure region above the wing (Bernoulli's Theorem). This pressure difference creates induced drag which is overcome by the power of the engine(which gets its energy from fuel)so we can fly around and enjoy ourselves.
This "downforce" you talk off only has effect on the earth (or aircraft floor in this case) when close enough to ground effect pressure wave. ie- you will not get crushed by a 400 ton 747 admiring it from below on short final.
Some may comment but I think ground effect height is a function of wingspan yes??? Not sure.
Ask yourselves this then....
If all energies must remain constant (the very principal of Bernoulli's Theorem), and the birds are exerting energy by flapping there wings, then where does this energy go?
Does it simply disolve as sound from the wings?
I think that the birds flying around in the middle of the cabin having no ground effect on the cabin are flying in space totally seperate from the aircraft using there own energy.
Therefore weight will decrease and the aircraft remaining in its current configuration will climb. And the birds will have to as well of course to remain in the centre of the cabin.
As for pressurisation, it will allow the birds to flap there wings slower to get the same lift to remain airbourne.
GW
