October 9th 07, 09:41 PM
posted to sci.physics,rec.aviation.piloting,alt.usenet.kooks
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Airplane Pilot's As Physicists
Le Chaud Lapin wrote in
oups.com:
On Oct 9, 3:31 pm, Sam Wormley wrote:
Ref:http://www.physlink.com/Education/AskExperts/ae627.cfm
Question:
If an airplane wing provides lift (an airfoil), how does a plane fly
upside down?
Asked by: Lee Hathcox
Answer:
The same way that your hand gets pulled upwards if you stick it out
the
car window and tilt it. The lift of an airfoil is determined by two
things - the shape of the wing, and it's angle of attack. Angle of
attack is the angle between the flat surface of the wing, and the
oncoming air stream. So when I roll the airplane upside down... if I
push the stick forward, that pushes the nose of the plane towards the
sky, and increases my angle of attack, even though I'm upside down.
So,
the shape of the wing doesn't change, and it pulls me down, but the
angle of attack I control, and I can make it push me up. So when the
lift from angle of attack in the up direction, exceeds the lift from
the shape of the wing, in the down direction, you can balance the
force
of gravity acting on the plane. You can see the influence of angle of
attack, because even if your hand isn't shaped like a wing, you can
see
how the angle and the force of the air push it in whichever direction
you choose.
Even though this (new) thread is not about what causes a wing to lift,
I just wanted to say for the record that I agree with this answer,
that it is both AoA and curvature of the wing.
Quick, call NASA.
Bertie
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