Thrust
Throwing
the airplane is what gives it the ability to move
anywhere at all. If there was no wind and you let an
airplane go, it would simply fall to the ground.
Depending on the angle the plane is thrown, the thrust
could be either purely horizontal or partially
vertical as it acts on the plane. If the plane is
thrown purely horizontally, then it should gradually
fall to the ground as it glides forward. This is
because the only forces working on it vertically are
gravity and lift, which are addressed on their own
page.
Even
so, the thrust has control over the plane’s altitude,
because the thrust is what allows the plane to
generate lift.
Drag
Like
all fluids, air has viscosity. As a plane glides
through this fluid, air particles rub against it. The
rough surface of normal printing paper can cause a
large amount of drag, as particles get “caught” in the
texture of the wings. This is why origami paper is so
excellent for building paper planes: The texture is
very smooth, and the light weight allows the plane to
fly longer without falling as much. Minimizing drag on
your airplane will let thrust have a stronger effect,
and thus allow the plane to get more lift.