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KIDS: Our World!
EVAN: Hey Globey! You're probably wondering why I'm
wearing all of these streamers. Well, I want to find out how
aerodynamic I am. Turn on the fan Charlie.
See, aerodynamics is the study of how efficiently air flows
around an object... like an airplane, or a car, or
...well, Me! Alright, that's enough Charlie, turn it
off...TURN IT OFF!
One of the best ways for scientists to study air flow
around objects is in a wind tunnel. A wind tunnel is an
enclosed space where the air flow over an object can be
carefully controlled and studied. There are 4 types of
wind tunnels: subsonic, transonic,
supersonic and hypersonic.
The NASA Langley Research Center has all of these types
of tunnels and is one of the most extensive wind tunnel
facilities in the world. Each type of wind tunnel is
used to study an object in a different wind speed.
These wind speeds are based on the speed of sound, which is
about 1,235 kilometers per hour
depending on altitude and air temperature. In warmer air,
sound travels even faster.
So the speed of sound is how fast sound waves travel through
the air. For example, if I were standing in a field and I saw a
lightening bolt 1.6 kilometers away, it would take 5 seconds
from the time that I saw the flash to hear the thunder
...the thunder is traveling at the speed of sound or Mach 1.
[thunder sfx]
What...I was just tying my shoe.
Wind tunnels measure air flow, or how fast the air is moving,
using the same scale used for the speed of sound.
Subsonic wind tunnels are used to study the airflow around
objects that are slower than the speed of sound
...like cars and commercial jets. Transonic wind tunnels
are used to study air craft that can fly around the speed
of sound. Supersonic and hypersonic tunnels are used to
study flight beyond the speed of sound. In fact, hypersonic
wind tunnels can study flight at up to 7 times
the speed of sound! But how do the engineers at NASA get a
plane to move that fast in an enclosed area?
They don't. The object they're testing stays
still and the air moves instead.
PETE JACOBS: We use wind tunnels to provide information
on the aerodynamics of various types of vehicles.
We can do that in a safe way Ėvery controlled conditions in
the wind tunnel. We don't have to build a full size airplane
and risk a pilot's life. We always test new configurations
in a wind tunnel first. Make sure they're safe.
Understand their characteristics, and then we
move on to the full size airplane.
EVAN: So different types of wind tunnels are used to test
different effects the wind has on an air craft flying through
the air. For example, The NASA Langley 14 x 22 Foot Sub Sonic
Tunnel is used to test certain objects that travel at less
than Mach 1 or less than the speed of sound.
FRANK QUINTO: The 14x22 is mainly designed to test low
speed performance of aircrafts. Low speed testing is important
to airplanes in that it's very important to safely take off
and land. We consider take off and landing the most important
part of a flight. Because if you don't take off and land
safely, the rest of the flight doesn't mean anything. On the
other hand, we also test other things besides aircraft in our
facility. We test structures
to see how wind flows around it. Anywhere from large
buildings to radar structures.
We also test vehicles such as Humvees.
And recently, we just got into testing motor sports
such as Nascar and indy racers.
And we also test parachutes as well as a wheel chair in 1979.
EVAN: The NASA National Transonic Facility uses
nitrogen gas to study the flow over wing sections and other
models. Because this wind tunnel is Transonic, it's used
to test objects that are meant to fly at speeds around Mach 1.
Just as sound moves faster in warmer air, warmer temperatures
in the wind tunnel make the air move faster. The Langley 8-
Foot High Temperature Tunnel is a hypersonic tunnel that uses
super heated gas to simulate speeds up to Mach 7.
That's 7 times the speed of sound! NASA even has a wind
tunnel that's built just to study how air flow affects air
craft that are spinning out of control.
That makes Globey and me dizzy.
Hold on GLOBEY!!
You know, Globey, the wind tunnels at NASA Langley
Research Center are helping to make air travel even safer and
a lot faster. And you won't believe some of the other
things that are tested in NASA's wind tunnels Ė cars and
boats and even the material for Olympic swimsuits. Leave it to
NASA to find a way to test aerodynamics
without even stepping outside!
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KIDS: Our World!
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