Gliders!
In its simplest form, a glider is an unpowered aircraft, an airplane without a motor.
While many of the same design,
aerodynamic and piloting factors that apply to powered airplanes also apply to gliders, that lack of a motor changes
a lot about how gliders work.
Gliders are amazing and graceful machines, and are about as close as humans can get to
soaring like birds.
From paper airplanes to the space shuttle during re-entry, there are many types of gliders.
Three basic forces act on gliders: lift, gravity and drag (airplanes have a fourth force: thrust):
Lift is the all-important force, created by the wings and counteracting the weight, which allows an aircraft to stay aloft.
In the case of a glider, the lift is enhanced through the use of highly efficient wings.
Without an engine, a glider's first problem is getting off the ground and up to altitude. The most common launching method
is an aero-tow. A conventional powered plane tows the glider up into the sky using a long rope. The glider pilot controls
a quick-release mechanism located in the glider's nose and releases the rope at the desired altitude.
The wings on a glider have to produce enough lift to balance the weight of the glider. The faster the glider goes the more
lift the wings make.
If the glider flies fast enough the wings will produce enough lift to keep it in the air. Since there's
no engine, the glider has to generate speed in some other way. Angling the glider downward, trading altitude for speed,
allows the glider to fly fast enough to generate the lift needed to support its weight.
