6H SUNDAY, APRIL 24, 2005 NEWS ILLUSTRATED sun-sentinel.com/theedge • SOUTH FLORIDA SUN-SENTINEL
Air hitting the surfaces of the plane
The rudder slows its forward motion. Drag is
Whether you have a cut-and-paste paper plane or helps the pilot
turn the plane left
generated by every part of the plane
and also by lift. Lift never pulls directly
a simple folded plane, there are four forces affecting or right (yaw). up, but rather tugs up and a little back,
and that backward pull also
contributes to drag.
its flight — lift, drag, weight and thrust.
Lift is generated mostly by the wings of
the plane as it moves through the air. In
order for the plane to fly straight and level, R
it must generate enough lift to oppose Wings
the most lift.
HOW LIFT WORKS
1. Front edges of 2. Air going over the top of
the wings are the wings speeds up as it
slightly higher than goes across them, causing Elevators help the pilot change
the back edges. Lift a slight upward suction. the plane’s angle of attack and
R control whether the plane goes up
AI or down (pitch).
3. Air traveling under the Wing
wings slows down as it The speeding up and
gets shoved by the slowing down of the
bottom of the wing. air is what creates lift.
Flaps are used in traditional airplanes to create extra lift Ailerons are used to turn the
during takeoff and landing. But they also can add extra drag. plane (roll) and keep it level.
To generate lift, the thrower must
create enough thrust to help the plane
overcome the drag and its own
weight. Because paper planes
don’t have the constant thrust
of an engine, drag slows the
Comparing it to the real thing
plane down until it can Flaperon
no longer generate The F-16 Fighting Falcon
enough lift to uses many of the same
oppose its 3 WEIGHT Lift
techniques to fly as the
weight. If lift pulls harder than
paper airplane, but with Air
weight pulls down,
a few exceptions. Real jet
the airplane begins to
wings have more mass
rise. If weight pulls
and the top has a slightly Air
harder, the plane falls.
curved shape to create Wing
more lift. 1. Extra lift is also created by
STABILITY a set of flaperons on the wings’
There are two points on a plane that determine if it will be stable in flight: trailing edge. They maintain
(combines flaps lift at high angles of attack.
Center of pressure is the point along the length of the plane
where aerodynamic forces of lift are equal on either side. and ailerons)
Center of gravity is the point where the If the center of gravity is forward of the 3
weight of the plane is equal on either side. center of pressure, the tail elevaor must
be adjusted up to compensate.
The results: A center of gravity at or in front of the center of pressure will likely make Air intake for jet engine Leading edge flaps
for a stable flight. A center of gravity behind the center of pressure is more unstable. improve lift and reduce drag 2. Drag also can be increased
by the moving flaps, which
slow down the plane for
Based on the forces of lift, drag, weight and
thrust, here are some suggestions to help your
airplane make a turn or fly on a straight path:
To correct a bad flight path
PROBLEM: Too much
rapid lift causing a stall.
down the rear edge 3. Weight (42,500 lbs.) and
of the tail wings center of gravity can change
(elevators) to create after a missile is launched or fuel
more drag. is spent, so the pilot or plane
PROBLEM: Twisting motion.
must constantly adjust the
controls to keep it balanced.
PROBLEM: Too little lift causing a plunge. sure the body and
wings of the plane
are not twisted.
Maneuver SOLUTION: Bend up
LEFT TURN: Bend the back edge of the the rear edge of the
right main wing (aileron) down, and bend
the back edge of the rudder to the left.
tail wings (elevators) 4. Thrust compensates for
to create more lift. the weight through a turbo-
fan engine with afterburner
capable of producing speeds
Build your own Air Force of up to 1,500 mph.
You can perform your own aerodynamic
experiments using easy-to-build paper airplanes. CLASSIC DART FAST FLYER GLIDING WING
Cut-and-paste planes, such as the one on this Models online
page, are designed to look like real airplanes. Print the patterns to build these
The weight of the plane is planes and more in our online
distributed for optimal Paper Airplane Garage. Pick your
aerodynamic stability. own color schemes and design at
Traditional paper airplanes, sun-sentinel.com/theedge
such as the classic dart, differ
in that they don’t have a tail
and only require folding.
Yet they follow the same Usually flown by bored people in Shorter than the classic dart and a Nice, wide plane with an unusual
aerodynamic rules offices, lectures and classrooms little harder to make, with a total triangular fold on the bottom that
that all airplanes do. CUT-AND-PASTE the world over. Seven folds and of 12 folds. Glides smooth and far. requires a tucking step. The gliding
F-16 throw — there isn’t anything This flyer looks more complicated wing lacks a central crease but
difficult in making this plane. than it is. glides smooth and far.
SOURCES: The World Record Paper Airplane Book, Ken Blacburn & Jeff Lammers; About.com; U.S. Centennial of Flight Commission; Aircraft Engine Design; Federation of American Scientists; HowStuffWorks Staff graphic/Hiram Henriquez firstname.lastname@example.org