A
glider
is a special kind of
aircraft
that has no engine.
There are many different types of glider aircraft.
Paper airplanes
are the simplest gliders to build and fly.
Balsa wood or styrofoam toy gliders are an inexpensive
vehicle for students to
have fun
while learning the basics of
aerodynamics.
Hang-gliders are piloted aircraft having
cloth wings and minimal structure. Some hang-gliders
look like piloted
kites,
while others resemble maneuverable parachutes.
Large piloted gliders have standard aircraft parts, construction, and
flight control systems, but no engine.
The
Space Shuttle
returns to earth as a glider; the rocket engines are used only
during liftoff.
Even the Wright Brothers
gained piloting experience through a series of
glider flights
from 1900 to 1903.
In flight, any glider has three forces acting on it
as compared to the four forces that act on a
powered aircraft.
Both types of aircraft are subjected to the forces of
lift,
drag, and
weight.
The powered aircraft has an engine that generates
thrust, while the glider has
no engine and, therefore, no thrust.
Forces are
vector quantities
having both a magnitude and a direction.
The weight acts through the
center of gravity
and is always directed towards the center of the earth.
The magnitude of the weight is given by the
weight equation
and depends on the mass of the vehicle plus its payload.
The lift and drag are
aerodynamic forces
and act through the
center of pressure.
The drag is directed opposite to the flight direction,
and the lift is directed perpendicular to the flight direction.
There are many factors
that influence the magnitude of the
lift
and
drag
forces.
In order for a glider to fly, it must generate lift
to oppose its weight. To
generate
lift, a glider must move through the air.
The motion of a
glider through the air also generates drag. In a powered aircraft, the
thrust
from the engine opposes drag, but a glider has no
engine to generate thrust. With the
drag unopposed,
a glider quickly slows down until it can no longer
generate enough lift to oppose the weight, and it then falls to earth.
Activities:
Guided Tours
-
Forces on a Glider:
-
Gliding Flight:
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