Ultralights
and Conventional Planes: What's the Difference?
Joe Duff,
Operation Migration Pilot
Conventional aircraft differ from ultralight aircraft in more than
just size and appearance. The pilot controls them in different
ways, too.
Understanding Center of Gravity
Our ultralight aircraft use a method of control called weight
shift. Look at the photo above. The wing is like a hang glider wing; the
trike
(or
three-wheeled cockpit and engine) hangs from the center of gravity of
the wing.
If you've
ever tried to balance a pencil on your finger, you've played with center
of gravity. The
center of gravity is the average location of the weight of an object.
When an object is suspended so that it can move freely, its center
of gravity is always directly below the point of suspension. The
center of gravity is very important in a conventional
aircraft. If you load all the
heavy stuff in the back, the aircraft will be out of balance like a
teeter totter and the nose will be too high. This can cause a crash.
The same is true if you load all the heavy stuff in the front. But
it does not matter how you load a trike, because the trike still hangs
from the center
of the wing.
Comparing
Wings
Wings
of conventional aircraft have flaps and rudders, which are small sections
of the wing that move. The flaps or rudders push up or
down
against
the air, moving the wing up or down. In a weight shift aircraft like
our ultralights, the entire
wing moves, not just small sections of it. This is safer because
it
takes many cables, pulleys and hinges to connect those moving
parts
of the wing to the pilot's control stick. A trike has only
one moving part: the pivot point where the wing attaches to the
aircraft.
Anatomy
of the Ultralight
|
North
Wing
(no kingpost) |
Do you see
the two bars that hold the wing on? The back bar is bigger and holds
the weight. It is called the mast. The front
bar is lighter and removable. It is called the downtube. The
bar we steer with is
the control bar. The kingpost is
that bar that sticks up above the wing and holds the top flying
wires that support the wing when
the trike is
on the ground. Because those top wires can trap a bird in flight,
we prefer to use the North Wings with no kingposts.
But
the
Zoom
wings
(with
the
kingpost)
fly slower and help
us stay
with the birds.
Journal
or Discussion Questions
- Center
of gravity is important bird flight too. Where is a Whooping crane's
center of gravity? Why do cranes and herons
fly differently? To discover the amazing answers, explore How
Birds Fly.
Share your new knowledge with friends or family.
- Why is
it safer for cars and trucks to have low centers of gravity, or
to have their centers of gravity located close to the road?
- Learn
more about the ultralight planes: How Does the Pilot Steer the
Ultralight?
- Make
a two-column chart to compare ultralights with conventional planes.
|