These particles experience lift forces which are similar in magnitude to the weight of the particle.
The lift force occurs because the air has a lower pressure just above the wing and higher pressure below.
This will result in a lift force generated which in turn rotate the blades.
This also is a way to intuitively explain why airfoils generate lift forces.
The transverse force on the particles is the lift force.
This would produce a lift force around the entire edge of the aircraft, allowing it to land "flat".
The birds flying behind will receive lift force from these up-wash vortices.
These two features create a large amount of lift force as well as some additional drag.
The development of general thrust is relatively small compared with lift forces.
Is the net lift force constant or increasing with altitude?
