Category FLIGHT and M ОТІOIM

eronautics is the science of building and flying aircraft. The term covers scientific study, design, and technology. It also includes the manufacture and operation of all types of aircraft, both lighter than air (such as airships) and heavier than air (such as airplanes).

Aeronautics involves a great variety of scientific and engineering disciplines. Aerodynamics and propulsion are important in aeronautics. So are materi­als, structures, control systems, and computing.

Energy from the Sun passes through the atmosphere’s layers to warm Earth’s sur­face. The surface then warms the atmos­phere. The warm air rises and draws in more air underneath to replace it. These air currents caused by the Sun and also by the spinning motion of Earth are responsible for the weather.

Some gases in the atmosphere are very good at soaking up warmth instead of letting it escape into space. These gases make the atmosphere warmer overall. The rise in temperature caused by these gases trapping heat is called the greenhouse effect, and the gases that trap the heat are known as greenhouse gases. Water vapor, carbon dioxide, and methane trap the most heat.

Without the greenhouse effect, the world would be about 60°F (33°C) cold­er than it is now. The world is gradually warming up, however, in a process called global warming. Many scientists believe this is happening because of the increase in greenhouse gases produced
by human activities. When fossil fuels such as coal and oil are burned, they release carbon dioxide, which traps heat.

Depending on how much the atmos­phere warms up, global warming could cause droughts in some parts of the world, floods in other parts, and more

BLUE SKIES AND RED SUNSETS

Air is colorless, so why is a clear sky blue? Sunlight contains all the colors of the rainbow mixed together. As sunlight streams through the atmosphere, it hits air molecules. The molecules scatter the light in all directions, but the blue part of the light is scattered more than the other colors, because its wavelengths are shorter. The sky, therefore, looks blue in every direction.

Brilliant red sunsets are also caused by light scattering. When the Sun is low in the sky just before it sets, sunlight travels more than thirty times farther through the atmosphere to reach the eyes of an observer than it does when the Sun is high in the sky. Most of the blue part of the sunlight is scattered out, leaving the red and orange parts of the light (with their longer wavelengths) to give the sunset those colors.

violent storms everywhere. If a warmer atmosphere melts the polar ice caps, the sea level could rise enough to flood coastal cities. Crops could fail in some places as the climate changes. Many people believe the effects of global warming are already being seen.

The introduction of jet planes brought about a revolution in passenger flying. The De Havilland Comet first flew in 1949 and went into service in 1952. It was followed by the Boeing 707, which could fly at 580 miles per hour (933 kilometers per hour) at 40,000 feet (12,190 meters). When the 707 entered service in 1958, critics argued that no airline would be able to fill its 130 seats. By 1969, however, the Boeing 747 was offering seats for 350 passengers.

Turboprop airliners, such as the Vickers Viscount and Lockheed Electra, proved briefly popular. Turboprop planes have gas turbine engines that turn propellers. They were slower than jets, but they were quiet and efficient. These aircraft were soon replaced, how­ever, by new medium-size jets.

The commercial aerospace industry of the late twentieth century had to

PRESSURIZED CABINS

The air is very thin at high altitudes, and early pilots flying above 10,000 feet (3,050 meters) would have needed oxy­gen tanks to breathe. A better system, introduced during World War II, was the pressurized cabin. Pressurized cabins were first used commercially in 1940, in the Boeing 307. After the war, pressur­ized cabins became standard on aircraft carrying passengers.

Commercial aircraft fly between 30,000 and 40,000 feet (9,150 meters to 12,200 meters). Whatever the temper­ature and altitude may be outside, the compressed air inside a pressurized cabin allows people to function as they would at lower altitudes. The pressurized air gives passengers enough oxygen to breathe comfortably. The introduced air system also maintains a comfortable temperature.

The pressurized air, which comes from compressors in the aircraft engines, flows through the wings to air condi­tioning units under the floor of the cabin.

It is mixed with filtered air already in the cabin (the filters trap any microbes) and is circulated in a continuous flow that dilutes odors and regulates temperature.

The air in the cabin changes every two to three minutes. In spite of the general belief that airplane air is full of recycled germs, airline passengers breathe cleaner air than most office workers.

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anticipate public demand for the future. Did passengers want cheaper fares in bigger aircraft, like the Boeing 747 and Airbus 380? Or would they pay more for the high-speed flights offered by the supersonic Concorde? The 747 won the commercial battle easily. Boeing 747s are still being built, while Concorde was retired in 2003. Only sixteen Concorde planes were ever flown commercially.

By 2000 Boeing aircraft had come to dominate the global market in com­mercial aviation. Boeing’s main rival is the European consortium Airbus Industries, a group of aerospace compa­nies that makes the Airbus family of commercial jets.

very part of an aircraft has been carefully designed by one or more aircraft designers. The materials used and the shapes of aircraft have changed over the years, but the impor­tance of design remains the same.

Four Aspects of Aircraft Design

There are four main subjects an aircraft designer must understand before an air­craft can be designed: aerodynamics, propulsion, materials and structures, and stability and control.

Aerodynamics is the scientific study of how air flows around an airplane. Propulsion is all about engines, which provide the thrust to move an airplane through the air. Materials and structures
cover what an airplane is made from and how it is built. Stability and control are concerned with how an aircraft flies and how its flight is controlled.

The shape and size of an aircraft depend on what it is designed to do. In other words, form follows function. Airliners have to be big enough to carry a certain number of passengers and their luggage. Fighter planes have to be small, highly maneuverable, and well armed. Cargo planes have to be large and pow­erful enough to carry huge weights of cargo, and they need big doors for load­ing and unloading their cargo easily.

Some use of airships has continued. Graf Zeppelin was briefly used during World War II by the Germans, but it was scrapped in 1940. The U. S. Navy contin­ued to use airships into the 1960s. In 1960 one of its airships flew for 95 hours and 30 minutes without landing or refueling once.

Today, airships are flown mostly for fun or for publicity and media work. There is growing interest, however, in new kinds of airships using modern technology. With modern materials and helium gas, a new generation of airships would be safe, efficient, and able to carry cargo and passengers for very long distances. Cruising at low level, an airship can provide spectacular views for passengers more interested in scenery than fast flight times.

Airships are also environmentally friendly. They use less fuel than air­planes, and they are quiet. Airships do not require airports with runways. Their main disadvantage is their slow speed. Hindenburg (the fastest airship) had a top speed of only 84 miles per hour (135 kilometers per hour). The largest airship currently flying, Spirit of Dubai, a Skyship 600 design, is limited to 50 miles an hour (80 kilometers an hour). Another disadvantage is that airships cannot fly high enough to cross the highest mountain ranges, such as the Rocky Mountains in North America or the Himalayas in Asia.

Current interest in airships focuses on their potential use as floating telecommunications centers or as trans­portation for heavy cargo. A German airship project called CargoLifter pro­poses to carry payloads of about 165 tons (150 metric tons) at a height of 6,560 feet (2,000 meters) for several thousand miles. About the same size as the Graf Zeppelin and Hindenburg, this modern airship can carry three times the payload of those earlier aircraft, because it is much lighter when unloaded. The CargoLifter is semi-rigid, and, instead of a heavy metal frame like a Zeppelin’s, it has a strong lengthwise keel, like a ship. The keel holds the cargo bay, flight deck, crew quarters, and engines.

Aircraft designers are also working on hybrid craft that combine airship and airplane. Such aircraft would need a takeoff run to get airborne, like most airplanes. They would also generate some lift from their shape as well as from the gas inside them. For maximum lift, a hybrid airship would have an effi­cient aerodynamic shape, such as a disk or an aerofoil (flying wing). The airship of the future might well look like the flying saucer of science fiction.

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SEE ALSO:

• Aerodynamics • Balloon • Future of Aviation • Hindenburg

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Date of birth: August 5, 1930.

Place of birth: Wapakoneta, Ohio.

Major contributions: First person to pilot the docking of two space vehicles; first person to set foot on the Moon. Awards: Presidential Medal of Freedom; Congressional Space Medal of Honor; NASA Distinguished Service Medal; Royal Geographic Society Gold Medal; Federation Aeronautique Internationale Gold Space Medal; and many more honors, awards, and honorary degrees.

orn on a farm in rural Ohio, Neil Armstrong took his first airplane flight at age six. He quickly became interested in aviation. Armstrong spent many hours of his childhood building model planes and reading books about flying. He started flying lessons at age fourteen and earned his pilot’s license two years later.

After graduating from high school, Armstrong began studying aeronauti­cal engineering at Purdue University in Indiana. He interrupted his studies to serve in the U. S. Navy from 1949 to 1952. During that time Armstrong flew as a fighter pilot in the Korean War and earned two Gold Stars. After his service in the Navy ended, Armstrong became a civilian again. He graduated from Purdue and became a test pilot for the government. From 1955 to 1962, Armstrong flew more than 1,100 hours, testing many different kinds of aircraft.

In September 1962, Armstrong joined the National Aeronautical and Space Administration (NASA) as an astronaut. He was one of the few civilian astro­nauts. In 1966 Armstrong made history on his first space mission, Gemini 8, when he became the first person to maneuver one spacecraft to dock with another in space.

Early in 1969, Armstrong was named as commander and pilot of the Apollo 11 mission that aimed to take the first peo­ple to the Moon. Also on the crew were Buzz Aldrin and Michael Collins, both experienced astronauts.

On July 16, 1969, the trio blasted off from Florida. A few days later, they

entered orbit around the Moon. Armstrong and Aldrin climbed into the lunar landing craft, the Eagle. Collins remained in orbit aboard the command module, Columbia. The two craft sepa­rated, and Aldrin piloted the Eagle down to the Moon’s surface. Shortly after 4:00 p. m. on July 20, the landing craft touched down. Armstrong announced by radio, “The Eagle has landed.”

For the next six and a half hours, the two astronauts prepared for their his­toric walk on the Moon’s surface. Just before 11:00 p. m., Armstrong stepped down the ladder onto the Moon’s sur­face. As he did so, he said, “That’s one small step for man, one giant leap for mankind.” A camera on the side of the spacecraft displayed the historic step to millions of people around the world watching on television.

Armstrong and Aldrin took some rock samples, set up some experiments, and placed a U. S. flag on the Moon. Fired by rockets, the ascent stage of the lunar module took the astronauts safely back to the Columbia on July 21. The next day, they began the return trip to

О Most of the photos from the Apollo 11 mis­sion were of Buzz Aldrin taken by Neil Armstrong. This is one of the few clear photographs of Armstrong, showing him next to the modular equipment storage assembly of the Eagle.

Earth. Columbia splashed down in the Pacific Ocean on July 24.

Officials worried that the astronauts might bring back some unknown space germs with them. Armstrong, Aldrin, and Collins were held in isolation for more than two weeks. When finally released, they were celebrated in cities across the United States and in many countries around the world.

From 1970 to 1971, Armstrong served NASA in an administrative job. He then resigned and became a professor of aerospace engineering at the University of Cincinnati in Ohio until 1979. Later Armstrong worked for companies in the aerospace industry. Armstrong also helped lead the commission that investi­gated the fatal loss of the Space Shuttle Challenger shortly after takeoff on January 28, 1986.

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SEE ALSO:

• Apollo Program • Astronaut

• Challenger and Columbia • NASA

• Spaceflight

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In a hot air balloon, the heat comes from a propane gas burner. The pilot turns on the burner to send hot air into the balloon. The balloon is made of a tough, nonflammable material such as nylon

BALLOON JUMP

The world’s longest delayed-drop parachute jump was made from a balloon. On August 16, 1960, Captain Joe W. Kittinger jumped out of a balloon 102,800 feet (31,333 meters) above New Mexico. He fell 84,700 feet (25,817 meters) before his para­chute opened. In 1984, Kittinger became the first person to fly the Atlantic Ocean alone in a balloon.

He flew from Maine to Italy in about 86 hours.

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or polyester. The bigger the bag, the more weight (payload) the balloon can lift. Passengers ride in a basket or similar structure hanging beneath the balloon. To descend for landing, the pilot releases air from the top of the balloon. Hot air balloons are popular with sports balloonists.

Gas balloons are usually filled with helium. This gas is safer than hydrogen because it does not catch fire. Gas bal­loons have more lifting power than hot air balloons. They can also go higher and stay aloft longer.

The largest type of gas balloon is a superpressure balloon. The pressure of gas inside the bag is higher than the pressure of the outside air. At launch, a superpressure balloon is only partly filled with gas. As the balloon rises, the gas expands and fills the bag. The

largest such balloons have a volume of more than 70 million cubic feet (2 mil­lion cubic meters), and they are unmanned aircraft.

Today, scientists find unmanned gas balloons useful for studying the weather and the upper atmosphere. Weather bal­loons carry radiosondes—instruments that measure temperature, humidity, and air pressure—which send back data by radio.

There are two kinds of bird flight: flapping and gliding. During flapping flight, the bird beats its wings up and down. The large primary feathers in the wing do most of the propulsion; the smaller secondary feath­ers help to maintain lift. The wings move in two directions while flapping: up and down and in a circular or figure 8 move­ment. The wingtips move faster and farther than the rest of the wings. The smaller the bird, the faster its wings flap.

The downbeat is the power stroke. On the downbeat, the wing feathers overlap closely so that air cannot pass through them but is instead pushed downward. The wing moves downward and forward. The primary feathers are bent back at their tips so the wing performs like a
propeller, pulling the bird forward. Power is produced on the upbeat, too, although less so than on the downbeat. As the wing moves upward, the primary feathers are bent back and move apart a little, fanning open to allow air to slip through the gaps between them. This reduces wind resistance and saves energy.

THE SPEED OF BIRDS

Peregrine falcon: 200 miles per hour (320 kilometers per hour) in a dive.

Spinetailed swift: 105 miles per hour (170 kilometers per hour). Canvasback duck: 65 miles per hour (105 kilometers per hour).

Pigeon: 60 miles per hour (96 kilometers per hour).

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bomber is a military airplane designed to attack targets on the ground or at sea by dropping explosives. A bomb, a metal case filled with high explosives, is just one of the weapons that a bomber can drop. These airplanes also may be armed with mis­siles, rockets, and guns.

Types of Bombers

Most air forces have bombers of two main types: fighter-bombers, also called strike fighters, and strategic bombers. Strike fighters, such as the U. S. Navy F/A-18 and the British Royal Air Force Tornado, can fly as fast as a fighter plane, although how they perform is affected by the weight of the weapons they carry. Their main role is to carry out tactical (battlefield) attacks on troop
concentrations, airfields, bases, ships, and supply routes. Some bombers oper­ate from naval aircraft carriers, while ground-attack airplanes such as the A-10 Thunderbolt fly over a battlefield to destroy tanks, artillery, or other small targets.

Strategic bombers, such as the B-52 and B-1B, are bigger planes. They can fly for 10,000 miles (16,090 kilometers), and even farther when refueling in the air from tanker planes. They are used to attack targets such as factories, military bases, ports, and cities. Even when they fly above 50,000 feet (15,240 meters), these planes are relatively easy to pick up on radar and so risk being shot down by fighters or ground-to-air missiles.

In 1989 the B-2 Spirit stealth bomber gave the bomber a new edge. Its revolu­tionary technology (a flying wing shape and special materials used in construc­tion) enabled it to sneak through radar defenses. Most early bombers had crews of eight or more, but the B-2 needs only two crew members and can

DROPPING BOMBS

A bomber’s weapons may be carried inside the aircraft, in a compartment known as the bomb bay, or attached to the outside of the aircraft. In the early days of air warfare (1914 to 1939), bombs were simply dropped from airplanes over the target area, frequently scattered to increase the chance of actually hitting the target. During World War II, large groups of bombers flew together in formation, often guided to the target by a pathfinder plane that marked the location of the target with flares. Accuracy improved as bombing and navigation equipment became more sophisticated, but bombs still were dropped in a fairly haphazard man­ner. A modern bomber can attack targets many miles away, using elec­tronic guidance systems to send its weapons precisely to their targets. Laser-guided bombs fly along a laser beam directed at the target either from the bomber or from another plane flying nearby.

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Date of birth: January 26, 1892 or 1893.

Place of birth: Atlanta, Texas.

Died: April 30, 1926.

Major contributions: First American woman to gain international pilot’s license; first African American woman to fly in the United States.

nown as “Queen Bess,” Bessie Coleman was the first African American woman to fly and a well-known early stunt pilot. Her example inspired other African Americans to take up flying.

Coleman was one of thirteen chil­dren born to a father who was part Native American and a mother who was African American. When she was nine, her father decided to move to Indian Territory—now the state of Oklahoma-hoping to escape the discrimination that he faced in Texas. Bessie remained behind in Texas with her mother and several sisters. Soon after, she finished elementary school and began working as a laundress. Bessie hoped to continue her education, but she could only afford to attend school for one more semester.

In 1915 Bessie Coleman moved to Chicago, where she joined a brother who lived there. Working in a barbershop as a manicurist, she became friends with Robert S. Abbott, publisher of the Chicago Defender, an important African American newspaper.

Newsreel and magazine stories about the new field of aviation interested Coleman. She applied to flight schools across the United States but was turned down because of her race and gender. Abbott suggested that she obtain the needed training in France, where there was less racial prejudice. Taking his

advice, Coleman learned French and saved her money to pay for lessons. She sailed for France in November 1920.

After several months of training, Coleman received her license to fly and returned to the United States. Black newspapers across the country hailed her as the first female African American pilot. To earn a living, Coleman decided to become a stunt pilot. To be success­ful, however, she needed to learn more tricks. Once again unable to find anyone in the United States to teach her, she returned to Europe early in 1922 for a few more months of training.

Back in the United States once again, Coleman took part in her first air show in September 1922. She was sponsored by Abbott’s newspaper and dazzled the crowd. A few weeks later, she appeared in another show in Chicago and went on to take part in several more.

Coleman dreamed of launching a fly­ing school for African Americans, but she could not afford to buy an airplane until early 1923. The plane she bought was an older model, and it stalled and crashed during a flight. Seriously injured in the crash, Coleman needed eighteen months to recuperate.

In the middle of 1925, Coleman began stunt flying again, putting on a spectacular show in Houston, Texas. Coleman also began touring to give lec­tures to black audiences about the thrill of flying. She hoped to use the fees she received to launch her flying school.

Early in 1926, she managed to buy another plane. Once again, it was an

BESSIE COLEMAN’S LEGACY

Coleman’s bravery and determination inspired African Americans in a time when they suffered from segregation and other forms of dis­crimination. In 1929, pilot William J. Powell and other African American aviators formed the first Bessie Coleman Aero Club. On Labor Day 1931, the club organized an all-black air show in Los Angeles, California. Similar aero clubs were founded in many cities across the country. Also in 1931, a group of African American pilots flew over Coleman’s gravesite in Chicago, a tradition still carried on today. Powell continued to honor Bessie Coleman by promoting avia­tion in the black community.

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older plane, one left over from World War I. The day before an air show in Jacksonville, Florida, Coleman and her mechanic took the plane aloft to test it. A loose wrench fell into the plane’s gears, causing the mechanic-who was piloting the plane-to lose control. The plane flipped over, throwing Coleman to her death. The plane then crashed, killing the pilot.

SEE ALSO: • Aerobatics • Barnstorming • Pilot