On Thu, 22 May 2008 08:22:49 -0500, Gig 601Xl Builder
wrote:

Mxsmanic wrote:
Stealth Pilot writes:

aeroplanes fly because of lift generated by pressure differences on
the wing surfaces.

Airplanes fly because the wings divert the air through which they pass
downwards, creating a downwash and exerting a force in doing so that engenders
an opposite force that is lift.

... these pressure differences are caused by the shape
of the aerofoil of the wing ...

The air is diverted because the wing has a positve angle of attack. It can be
perfectly flat and it will still generate lift.


If that were the case a 747 would have to be producing over 250,000
pounds of force straight down. Why then am I not crushed when a 747
flies over me?

bloody long wings combined with you being a bit slow on the uptake
(...I'm joking :-) )

it is 250,000lbs or whatever the aircraft weight is but it isnt a
point load and it is a variation in an existing unperceived pressure.

the pressure variations over the wing of a 747 are discussed in an
aero engineering book. because of the wing area involved and the speed
the pressure variations are a lot less than you'd think.
( I wish I could remember which book it was)

Stealth Pilot