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Old January 10th 06, 02:55 PM posted to rec.aviation.soaring
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Default Thrusting or Sucking (where's Howard Stern when we need him.)

Ok, here is another way this can be explained (if just
a bit inaccurate):

The critical point to consider is angle of attack.
You just need to think of the airflow meeting the wing
at a specific angle. If you now imagine the airflow
separating to move above and below the wing section
as two particles, you have the following explanation:

-The particles are going to separate at the leading
edge and meet up together approximatelly at the wing's
trailing edge.

-Because of the angle of attack (and of the wing's
thinkness), the air particle that will travel above
the wing section will have a greater discance to cover,
so it will have to run faster if it is to meet up with
the other particle which is traveling below the wing
section.

-Particles traveling at greater speeds (compared to
particles in neighboring areas) create areas of low
pressure -- just think: because the particles are running
faster over the wing compared to under the wing, there
are fewer of them in a specific area. Alternativelly,
you can take Bernoulli's word on this one.

-Now let's examine the situation from the perspective
of the wing. There is a low pressure above and a high
pressure bellow. The resulting force is thus upwards
(in relation to the angle of attack).

The only presumption which remains to be explained
is why the two particles have to meet at the back of
the wing section. The easiest way to gloss over this
is to consider that if this is not approximatelly the
case, an imbalance will be created whereby there will
be more air crossing below the wing section and a low
pressure area buildup at the top back end of the wing,
created by the lack of air (teh air has just not had
the time to reach there). This would probably invite
air from below the wing to bleed back up towards the
back top. In this case, the airflow above the wing
would separate from the wing section before the trailing
edge (does this sound a bit like a stalled wing?)

I don't know how much science there is behind this
explanation. I just find it a bit easier to swallow
than the Newtonian explanation. In my view the action-reaction
way of putting it (air is deflected downwards) is true,
but unable to shed any light on the mechanism. It is
just an energy checks-and-balances way of explaining
lift, which we already know occurs.

Alexander Georgas