Airflow and Downwash
The
diagram below shows an idealized depiction of the actual flow of air over an
airfoil. The reaction of the air
as a fluid to the shape of the airfoil creates upwash on the front part of
the wing and downwash on the rear part.
Downwash is the force that creates lift. In accordance with Newton’s third law, which states
that for every action there is an equal and opposite reaction, while the wing
forces large quantities of air down in the form of downwash, the air is
pushing back up on the wing with an equal magnitude. This force of the air pushing back on
the wing is part of what creates lift.
The more air that a wing diverts down, the more lift it can
produce.
Idealized depiction of air (a fluid) flowing over an airfoil, resulting in upwash and downwash. (http://www.aviation-history.com/theory/lift_files/fig4.jpg) Take a look at this photo
of the movement of the air behind the jet. A huge column of air moves almost straight down relative
to the ground. This is the
downwash created by the wings of the jet resulting in an opposing lift force.
(www.aviation-history.com/theory/lift_files/fig6.jpg) |
