Dear Amy: How do airplanes fly? — Thomas D., Pittsburgh, Pa.
Dear Thomas: In order to understand how
a heavy airplane can soar through the sky,
you have to begin to understand aerodynamics.
There are four forces in place when
an airplane flies through the air: thrust,
drag, lift and weight.
Thrust is the force that propels you forward,
such as that provided by the propeller
or engine on the airplane. Drag is the force
that presses against your hand when you
stick it out the window of a moving car. The
force is stronger if you squeeze your fingers
together. In order to fly, thrust must be
greater than or equal to drag.
The other forces in place are weight and
lift. Weight is the force of gravity that opposes
lift. As the plane moves forward on
the runway, the wings tilt up in such a way
that the pressure is on the bottom of the
wing and the air moves more quickly above
the wing, which results in lift.
To learn more about how planes fly, NASA
provides an explanation just for kids in
“How Do Planes Fly?” at nasa.gov/audience/forstudents/k-4/stories/ames-how-do-planesfly-text.html