Airplane Pilot's As Physicists
Mxsmanic wrote in
:
Randy Poe writes:
As I said, I lean toward the angle-of-attack arguments now. Take
a flat rectangle, tilt it into the wind. The wind blows against the
front which is also the bottom, not the back/top. So the
forces are on the bottom.
The essential feature of an airfoil is that it twists the flow of air
as it passes (or as the airfoil passes through still air, which is
equivalent, and that's how it works in airplanes). The air is
accelerated downward, and this engenders an equal and opposite force
that is lift.
So how does a wing produce lift? By twisting air downwards, creating
a downwash. Accelerating a mass of air downwards tends to accelerate
the wing upwards, and there's your lift.
The theory gets more complicated when you try to explain exactly how
and why airfoils twist an airflow. Just looking at a flat board with
a positive angle of attack, you'd think that it would twist the air,
and that's exactly what it does. But the devil is in the details.
Fortunately, aviators don't have to know or care about the details.
All they need to know is that a wing with a positive angle of attack
(and below the stall angle) will generate lift.
Lift, like so many other phenomena in physics, can be analyzed and
explained in a number of different, equally valid ways, depending on
one's point of view. All analyses and explanations converge on the
same reality. Of course, some explanations of lift are just plain
incorrect, and unfortunately a few of them are quite widespread.
Nope
Bertie
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