unheated air.
The 1800s saw much experimentation
in both lighter-than-air and heavierthan-
air craft. Several people worked
with gliders to establish the principles of
airplane design. Gliders are similar to
airplanes but they have no motor. Once
they are launched, they move through
the air as a plane does.
Early Aviation
On December 17, 1903, in Kitty Hawk,
North Carolina, Orville andWilbur
Wright made the first flight in an
engine-powered airplane. TheWright
brothers had experimented with gliders.
They chose the North Carolina coast for
their testing because of its strong winds.
Their first plane flight, with Orville
piloting, lasted 12 seconds and covered
120 feet (37 meters). By 1905 the
Wright brothers had improved their
plane to the point that it could fly 24
miles (39 kilometers) in 38 minutes.
During WorldWar I (191418) airplanes
began to change the nature of
war. Planes were first used to observe the
enemy from the air. Eventually countries
discovered that they could use planes for
dropping bombs. Pilots also learned to
shoot at each other in the sky.
Development of Modern Aviation
After the war people began to use planes
for commercial purposes, including
delivering mail. Pilots also began to
experiment with seeing how far they
could fly. A U.S. airmail pilot named
Charles Lindbergh became famous in
1927 for making the first solo flight over
the Atlantic Ocean.
Jet-powered aircraft were introduced on
a small scale duringWorldWar II
(193945). After the war jet planes were
improved and came into wide use.
Regular passenger jet services across the
Atlantic were started in 1958. Today
passenger jets fly people all around the
world every day.
Air Travel Safety
Airline safety became an important issue
in the second half of the 20th century.
In the United States a government
agency called the Federal Aviation
An early airplane flies over Chicago,
Illinois, in 1911.
Only a few
experimental
airplanes have
used rocket
engines. A
rocketpowered
airplane
called
the X-15 set
records for
speed and
height of
flight.
BRITANNICA STUDENT ENCYCLOPEDIA Airplane 57
Administration (FAA) was created in
1958 to monitor aircraft and to investigate
accidents. The FAA also operates
the air traffic control system, which
keeps planes out of each others way.
Human error, equipment failure, and
weather can cause accidents. But flying
is still far safer than traveling by car.
#More to explore
Balloon Glider Helicopter Wright,
Wilbur and Orville
Airship
The large aircraft that are often seen
floating over sporting events are commonly
known as blimps. These are actually
a type of lighter-than-air craft called
an airship. Airships were developed from
principles of ballooning. Like balloons,
they are filled with a gas that allows
them to float in the air. Unlike balloons,
airships are driven by engine-powered
propellers and steered with rudders. For
this reason they are also called
dirigiblesafter the French word
diriger, meaning to steer.
Most airships are long and cigar-shaped.
Some airships have a rigid frame supporting
the crafts surface fabric. Nonrigid
airships are simply big balloons
that rely on the gas to keep their shape.
Nonrigid airships are also known as
blimps. The main section of an airship is
filled with a gas that is lighter than air.
Helium is the most commonly used gas.
A car, or gondola, suspended below the
gas balloon holds the airships crew and
passengers.
Airships rely on several different features
to enable them to fly. The gas inside the
ship lifts the craft into the air. Engines
then propel the craft forward. The pilot
uses a rudder to steer the craft. Most of
the ship is filled with the lighter-than-air
gas. There are also compartments filled
with normal air. The pilot can make the
ship go up or down by controlling the
amount of air in these compartments.
The first propeller-driven airship flew in
1852 in France. Its engine was powered
by steam. The first rigid airship, with a
body made of aluminum, was built in
Germany in 1897. Ferdinand von Zeppelin,
the famous German builder, completed
his first rigid airship in 1900.
Akimel Oodham
#see Pima.
Akmola,
Kazakhstan
#see Astana.
A colorful airship flies over Dodger Stadium
in Los Angeles, California.
58 Airship BRITANNICA STUDENT ENCYCLOPEDIA
Aksum
Aksum, or Axum, was a powerful trading
empire that flourished in northeastern
Africa hundreds of years ago. Aksum
also was the name of the kingdoms
capital. It remains a city in northern
Ethiopia.
Aksums location between the Red Sea
and the Nile River helped to make it
one of the most important and wealthy
trading centers of its day. The items that
moved in and out of its ports included
ivory, hippopotamus hides, perfumes,
gold, and animals.
The kingdom was also known for its
architecture. Still standing in the central
square of the city of Aksum are some of
the carved granite obelisks made in the
kingdom. An obelisk is a tall, thin pillar
with a pyramid at the top. (TheWashington
Monument is an obelisk.) Some
Aksum obelisks may have marked
underground tombs of the kingdoms
rulers.
Aksum expanded as it grew more powerful.
In the AD 300s Aksum conquered
the kingdom of Kush to the north.
Aksums rulers then pushed west across
the Red Sea into southern Arabia. In the
600s and 700s the kingdoms hold
weakened as the Muslim Arabs emerged
as a power.
The people had been Christian since
the 300s. The Arabs allowed them to
keep the Christian religion because they
had once given refuge to followers of
Islams founder, the prophet
Muhammad. Today Aksum is
considered a holy city of the Ethiopian
Orthodox church.
#More to explore
Arabian Peninsula Eastern Orthodox
Churches Ethiopia Islam Kush
Muhammad
One of the obelisks from the kingdom of
Aksum stands in the modern city of the
same name.
BRITANNICA STUDENT ENCYCLOPEDIA Aksum 59
Alabama
The state of Alabama is located
in the center of the Deep South
of the United States. Because of its location,
the land that is now Alabama
played a role in many of the major conflicts
that shaped the United States.
These included battles with Native
Americans over control of the area, the
American CivilWar, and the civil rights
movement of the 1960s. Montgomery is
Alabamas capital.
Geography
Alabama lies in the southeastern United
States. The southern parts of the Appalachian
Mountains cover most of northern
Alabama. The land is rugged, with forested
hills and ridges. Southern Alabama
is a mostly flat plain. The climate is
mild. Summers are long and warm.
Winters are short and moderate.
People
People of European ancestry make up
almost three quarters of Alabamas
population. About one quarter of the
population is African American. Slightly
more than half of the people live in cities
or towns. Birmingham is Alabamas
largest city and industrial center. Mobile
is a port city on Mobile Bay. Tuscaloosa