One of
the first and most noticeable differences between a real
airplane and your typical paper airplanes is the
existence of a tail. Many real planes need a tail
because their wings don’t span the entire length of
their body (or “chord”). However, this isn’t true for
standard paper airplanes, so they don’t need a tail. The
body-length wings are able to provide the needed
stability, and in fact there are real planes that fly
without tails because they have such wings, such as the
B-2 Flying Wing Bomber shown below. (5)
http://www.paperplane.org/Aerodynamics/b2.jpg
Any
plane also needs its center of gravity to be ahead of
what is called the “Neutral Point” in order to remain
stable. However, if the center of gravity is too far
forward, the plane will nosedive quickly. An interesting
experiment is to put a paper clip on the front end of a
plane, and see how adjusting the back of the wings
affect the stability. Folding the back of the wings up a
tiny bit adds “elevator” to the plane, which reduces
speed but increases stability. The closer to the middle
the center of gravity is, the more sensitive the plane
is to the amount of elevator in the wings. Understanding
this relationship and finding the right balance is part
of the key to building superior paper (and real)
airplanes. (4)