Net Forces on
The external forces on an airplane in flight
heading westward are as follows:
gravity, thrust, drag, and lift.
They are not all along the same
The gravity represents the
weight of the aircraft.
is caused by air resistance on the aircraft.
thrust is due to the engine and propeller.
How does lift work?
According to Daniel Bernoulli who
presented his fact in 1738.
fluids (such as air), exhibit less force than slow moving
where p is the pressure,
is the density, and v
is the velocity.
A large velocity v
results in a small pressure p, and conversely a small
velocity v results in a large pressure p.
If we produce a surface such that
air takes longer to travel over the top than the bottom, the
surface will produce a net upward force. Such a surface is
airfoil and the net force is called
Bob Gardner, East Tennessee State University)