Category FLIGHT and M ОТІOIM

ollution is the process of making the environment dirty, dangerous, or in other ways unpleasant or unhealthy for people, animals, and plants. Flying contributes to pollution through the emissions from airplane engines and through noise and environ­mental damage around airports.

Transportation is a major source of air pollution in the United States and other industrial nations. Jet engines, like automobile engines, burn carbon-based fuel. During the burning process or com­bustion, airplane engines give off car­bon monoxide, carbon dioxide, hydro­
carbons (compounds of carbon and hydrogen), and nitrogen oxides (com­pounds of nitrogen and oxygen). These substances are all pollutants, and too many of them in the atmosphere can have damaging effects on people, on animals, on plants, and even on build­ings. Polluted air is unhealthy to breathe. Heavy concentration of pollu­tants around cities can form smog, reducing visibility and air quality and endangering the health of people.

Scientists believe that carbon-based pollutants are causing damage to Earth’s atmosphere. A buildup of carbon diox­ide gas in the atmosphere from burning fossil fuels-such as gasoline and avia­tion fuel-is thought by many experts to contribute to the greenhouse effect. The gases trap heat from sunlight, therefore contributing to global warming and climate change.

High-flying jet aircraft emit those gases close to Earth’s surface and at higher altitudes. The primary gas in jet engine emissions is carbon dioxide, which can linger in the atmosphere for up to a hundred years. Aviation emis­sions account for up to 4 percent of all global carbon dioxide emissions from the burning of fossil fuels. Carbon diox­ide combined with other airplane exhaust gases could be having a much greater impact on the air than carbon dioxide alone.

Most legislation passed in recent decades to cut air pollution has been directed at industry and automobiles. With aviation growth at around 5 per­cent a year, however, the development of cleaner aircraft engines is vital.

Airports also are a source of pollu – tion-not simply because of the number of airplanes using them, but because a busy airport draws in thousands of cars and trucks every day. Airport buildings and handling facilities consume a lot of energy and produce a lot of waste. Even the chemicals used to de-ice airplanes in winter pose a pollution risk to the soil and the water cycle.

NOISE POLLUTION

As air traffic increases, there are concerns about noise pollution. Anyone who has stood on a runway close to a jet plane taking off knows that it is very noisy. The loudness is measured in decibels. A jet plane taking off can reach 130 decibels. Supersonic planes also make a sonic boom. Protests about the boom ended airline plans to fly the Concorde on transcontinental super­sonic flights in the 1970s. Modern turbofan engines are more efficient and less noisy than the engines of fifty years ago, but many airports suspend flights at night so that local residents can sleep undisturbed.

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Some campaigners argue for cuts in flights or at least increased airport and airline taxes-and thus higher fares – to reflect the true environmental cost of flying. Aircraft manufacturers respond that new airplane engines are becoming increasingly efficient and clean. They also say the introduction of larger air­planes means fewer flights, less fuel burned, and therefore less pollution.

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SEE ALSO:

• Aircraft Design • Airport • Engine

• Fuel • Future of Aviation

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Solid-fuel rockets are the simplest and oldest type of rockets. Aircraft have been armed with solid-fuel rockets since World War I, when they were used to attack airships and observation bal­loons. Rockets fired from one aircraft at another aircraft are called air-to-air rockets. The airships and balloons were filled with hydrogen, which burned if a flaming rocket flew into it. The problem was that the planes of the day also were made of flammable materials, so firing rockets from them was dangerous. The rockets also were inaccurate and rarely hit their targets.

Small air-to-air rockets were used again in World War II. They enabled fighters to attack bombers without com­ing within range of the bombers’ guns. These small rockets were unguided-they were aimed simply by pointing the

О The Space Shuttle has two solid rocket boost­ers (SRB) that are strapped to its external fuel tank. The SRB are discarded about 2 minutes after liftoff, and they fall back to Earth to be retrieved and reused.

Robert Hutchings Goddard was an American scientist and inventor who developed the modern liquid-fuel rocket. He received patents for a liquid-fuel rocket and a two – stage rocket in 1914. In 1919, Goddard wrote a paper called "A Method of Reaching Extreme Altitudes," in which he talked about sending a rocket to the Moon. He was ridiculed at the time for even suggesting such a crazy idea. In 1926, Goddard suc­ceeded in building and launching the first liquid-fuel rocket. Powered by gasoline and liquid oxygen, the small rocket rose to a height of 41 feet (12 meters). Goddard went on to build bigger and more powerful rockets. Some of them climbed higher than

9,0 feet (2,740 meters) and went faster than the speed of sound. Goddard was the first person to steer a rocket by using vanes in the rocket exhaust, and he designed the first gyroscopic systems for guiding rock­ets. NASA’s Goddard Space Flight Center is named in his honor.

C Robert Goddard displays his liquid oxygen-gasoline rocket before its successful launch in 1926.

whole plane. In the 1950s, air-to-air rockets were replaced by guided missiles.

Solid-fuel rockets are used to help launch spacecraft. Space launch rockets are liquid-fuel rockets, but they can be made more powerful by strapping solid- fuel rockets around them. The solid rock­ets provide extra power for liftoff. Extra rockets used like this are called boosters. The Space Shuttle is launched with the
help of two solid rocket boosters (SRB). They burn powdered aluminum fuel with ammonium perchlorate oxidizer. The propellants are mixed as liquids and then set hard in a mold. A hole runs through the center of the rocket. When the propellants are ignited, they burn from the inside out. Once solid-fuel rockets have been lit, they cannot be turned off.

In the spring of 1909, Sikorsky built his first real helicopter. However, the machine would not fly. Another version failed to fly the following year, and Sikorsky decided to abandon the effort. As he later explained, “I had learned enough to recognize that with the exist­ing state of the art, engines, materials, and—most of all—the shortage of money and lack of experience. . . I would not be able to produce a successful helicop­ter at that time.”

Sikorsky turned his attention to designing airplanes, producing several models and flying them himself. In 1911, he earned an international pilot’s license, becoming just the sixty-fourth person in the world to have one. That year, Sikorsky’s S-5 plane set records by carrying three people more than 30 miles (48 kilometers) at 70 miles per hour (about 113 kilometers per hour). Another of his planes won an award at an air show the next year and took first prize in a competition held by the Russian armed forces. This success earned Sikorsky a job with a Russian company, where he worked on manufac­turing airplanes.

In 1913, Sikorsky produced a new design he called the Grand. This large airplane was powered by four engines – the first flying machine to have more than one. It also was the first to have the pilot and passenger areas fully enclosed. The Russian army used several dozen aircraft of this design as bombers during World War I (1914-1918).

Russian participation in the war ended when communists took control of the nation’s government and pulled the country’s troops out of the conflict. Sikorsky left his homeland in 1919 and eventually reached the United States.

Modern aerobatic aircraft can per­form maneuvers impossible for an ordinary airplane, such as torque rolls (rolling and sliding backward at the same time) or lomcevaks (tumbling end over end). Aerobatic

О The U. S. Navy’s Blue Angels, using F/A-18 Hornets, perform aerobatic movements at an air show in 2006.

planes are strong but very light in rela­tion to the power of their engines. Most use piston engines and propellers.

One outstanding aerobatic airplane is the U. S. Pitts Special. The first Pitts flew in 1947, and since then Pitts Specials have dominated aerobatic competitions. The later versions of this little plane remain close to the original design.

Formation teams perform their dis­plays with as many as sixteen aircraft, although a team of nine or ten is more usual. During a per-formance, aircraft change formations a number of times. They split up into smaller groups, fol­lowing the instructions of the team leader by radio. Pilots often use colored smoke trails to highlight the patterns they are flying.

Famous aerobatic teams include the Blue Angels of the U. S. Navy, the Thunderbirds of the U. S. Air Force, and the Red Arrows of the British Royal Air Force. Unlike other aerobatic performers, military teams usually fly jet planes. These planes fly faster than propeller planes and need more space to display their formations. The Thunderbirds fly the F-16 Fighting Falcon that has a top speed of 1,300 miles per hour (2,092 kilometers per hour).

Accidents are rare, but aerobatics are demanding. Pilots practice constantly to perfect new formations and sequences. They also must keep physically fit to cope with the stress of aerobatics, which subjects their bodies to strong g-forces (acceleration measured as multiples of the force of gravity at Earth’s surface).

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PATTY WAGSTAFF

Born in 1951 in St. Louis, Missouri, Patty Wagstaff flew with the U. S. aerobatics team from 1985 to 1996. She was the first female U. S. National Aerobatic champion, a title she won three times. Wagstaff was International Aerobatic champion in 1993. In 2004, she was elected to the National Aviation Hall of Fame. The Goodrich Extra 260 plane flown by Patty Wagstaff in the 1990s is displayed at the Smithsonian Institution’s National Air and Space Museum. Wagstaff has flown at air shows all over the world and says she likes the precision of aerobatics. "I like flying a perfect loop. . . a per­fect maneuver."

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SEE ALSO:

• Aerodynamics • Barnstorming

• Gravity

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The aerospace industry has cut thou­sands of jobs in recent years, however, because of a drop in orders due to finan­cial problems in the airline industry. A decline in airline business followed terrorist attacks on the United States in 2001. Rising fuel prices also hit airlines hard, and several major U. S. airlines have filed for bankruptcy in recent years.

The aerospace industry has also been troubled by disputes between the United States and Europe over government sub­sidies (payments to offset the cost of developing new aircraft). Boeing, facing stiff competition from the new, giant

Airbus A380, has complained to the World Trade Organization about low – interest loans made to Airbus by the European Union.

The space industry has been hit by uncertainty over plans for the future of manned flights. Programs such as the International Space Station (ISS) and a replacement vehicle for the Space Shuttle, however, continue to create demand and challenge the industry’s best workers. Aerospace manufacturers are facing another challenge, posed by envi­ronmental concerns—how to build quiet and fuel-efficient aircraft for the future.

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SEE ALSO:

• Aircraft, Commercial • Aircraft,

Military • Boeing • Curtiss, Glenn

• Wright, Orville and Wilbur

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Aileron and Rudder

he ailerons and rudder are two of the three control surfaces on an airplane (the third is the elevator). They are the moving parts that steer a plane through the air. The ailerons are panels in the trailing (back) edges of the wings. The rudder is part of an airplane’s tail fin.

Pilots use the ailerons and rudder together to make a turn. They learn how to steer their aircraft smoothly through a turn with the nose pointing in the right direction.

A good air traffic controller needs to have spatial awareness and mathe­matical abilities. Above all, a con­troller must stay calm under pressure.

He or she must be able to absorb data, assess a situation accurately, and make the right decision quickly. Fitness, good vision and hearing, and a clear radio speaking voice are also essential. A controller should be a good team worker because safe air travel requires cooperation from many people. Air accidents are rare, but near misses sometimes do occur. After the attacks of September 11, 2001, terrorism brought a new dimension of risk, adding to U. S. air traffic controllers’ responsibilities.

In 1981 air traffic controllers in the United States went on strike. They were protesting their increasing workload and the stress and dangers of handling more airplanes every year. The federal government dis­missed 10,000 controllers. To reduce pressure, however, a flow control system was introduced. Under this system, an airliner could not leave an airport unless landing space was available at its destination airport at the time it was due to arrive. This eased the stress on controllers who were handling the holding stacks of airplanes waiting to land.

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on a highway. The difference, of course, is that aircraft travel much faster than cars and fly at different heights. Several aircraft may be flying over an airfield while other planes are preparing to land or take off below. For safety, all these aircraft must keep safe distances apart, both vertically and horizontally. The normal vertical distance between air­craft, known as safe vertical separation, is 1,000 feet (305 meters) below 29,000 feet (8,840 meters) and 2,000 feet (610 meters) at altitudes above 29,000 feet (8,840 meters). For planes at the same height, a distance of at least 10 miles (16 kilometers) apart is regarded as safest.

In the United States each ARTCC’s zone is divided into smaller sectors. Around airports, the airspace comes under Terminal Radar Approach Control (TRACON). Each TRACON covers rough­ly a 50-mile (80-kilometer) radius of air­space, and within each airspace is at least one airport. Each airport also has its own airspace, with a radius of 5 miles (8 kilometers). Around some busy inter­national hubs, one main computerized center handles all traffic. London, for example, has one main center that con­trols air traffic in and out of the city’s five major airports.

At a small airport, controllers may have control of aircraft on the ground and in the air around their airfield. Small flight service stations (FSS) help and advise private pilots flying in coun­try districts or from small airfields.

At a larger, busier airport, different types of controllers may be assigned to

various tasks. Tower con­trollers keep a visual watch on aircraft as well as using radar. Approach controllers follow the movements of airplanes approaching and leaving the airfield, usually up to a distance of 50 miles (80 kilometers) and to a height of 10,000 feet (3,050 meters). Area controllers are responsible for planes flying at higher altitudes.

The duties of an air traffic controller include using the radio to pass instructions to pilots about takeoff and landing and to relay weath­er information. Controllers use radar to track airplanes during their flights and plot the locations of aircraft on charts (maps). They check aircraft speed, direction, and altitude and keep a record of all movements and commu­nications. Computers are vital to air traffic controllers for processing and accessing information.

In 1947 the U. S. Air Force became an independent service, free of U. S. Army control. After World War II, jets rapidly replaced propeller aircraft in the world’s major air forces. The first U. S. super­sonic fighter was the F-100 (1953). By 1958 the F-104 could exceed 1,400 miles per hour (2,253 kilometers per hour).

The mid-1940s to the 1970s was the period of the Cold War, when the United States confronted a hostile Soviet Union. Both sides set out on an arms race that included producing new warplanes. Changes in design of this period included the introduction of delta, sweptback, and swing-wing wing shapes. Other developments included the first V/STOL (or jump jet), more powerful engines, and new radars and missiles. Ejection seats were invented to allow a pilot to escape from a damaged airplane, even at high speed and great heights.

Both the United States and the Soviet Union developed giant bombers able to fly nonstop for 10,000 miles (16,090 kilometers). The biggest U. S. bomber was the B-36 (1946). Such bombers were designed to carry nuclear bombs and guided missiles. Planes also had to counter missile attacks-the first U. S. missile built to shoot down enemy planes was the Nike-Ajax of the early 1950s. Some military experts argued that bombers were obsolete (out of date) and that guided missiles would replace the piloted airplane. Strategic nuclear weapons systems were indeed developed,
using land-based and submarine – launched missiles. The piloted bomber did not disappear, however, and the B-52 is still in service today, more than fifty years after its first flight.

Passengers entering an airport must check in with their airline. On many
international flights, check-in time may be two or more hours before takeoff because of growing security measures at the world’s airports.

At the check-in desk, passengers’ baggage is weighed and labeled. Each passenger is allocated a seat in the plane and given a boarding pass. Baggage is checked by machines and security per­sonnel before being loaded into the baggage hold of the airplane. Security became a serious issue in the 1970s after a number of attempts by terrorists to hijack airliners. Even tougher security came into force at airports after the ter­rorist attacks of September 11, 2001. All airlines now impose strict regulations on what air travelers are allowed to carry, especially in small hand baggage taken into the cabin.

At the airport, passengers pass ^ through security gates before boarding their plane. Security checks involve body scanning and X-rays of all hand baggage. |jw Passengers may be asked to remove shoes, belts, and metal objects before they pass through the electronic scanning gates. Security officers make sure no weapons or explosives get on board the plane.

Passengers move through into

a departure zone to wait for their [___ .

flight. In large airports, they may ride from the main terminal to a smaller satellite terminal on a shuttle bus, monorail, or electric vehicle. While they wait, passengers can usually eat or shop in the airport facilities. They can check their departure information on monitors (each airline flight has a number to identify it).

The next step was the Apollo program itself. Launched in 1967, the program began with a disaster. Apollo 1 was being prepared for launch when, on January 27, 1967, its three-person crew climbed into the command module to perform a systems test on the ground. During the tests, a fault in the wiring started a fire. The module had been flooded with pure oxygen, which caused the fire to spread in an instant. Astronauts Ed White, Gus Grissom, and Roger Chaffee were trapped inside, unable to open the hatch in time to escape the flames. All three men died.

After a break in the program for investigation into the accident, NASA quickly redesigned the Apollo spacecraft with several added safety features. When the Apollo program resumed in late

1967, the unmanned Apollo flights 4, 5, and 6 tested the rocket and modules for safety and reliability. (There were no Apollo flights numbered 2 or 3.)

The first manned Apollo flight, by Apollo 7, took place in Earth orbit in

1968. Later that year, Apollo 8 flew around the Moon ten times and returned to Earth safely. In 1969, the landing module was tested in Earth orbit by the crew of Apollo 9. Apollo 10 repeated the

Apollo 8 mission, this time completing thirty-one lunar orbits. During the Apollo 10 mission, two astronauts flew the lunar module within 47,000 feet (14,300 meters) of the Moon’s surface.

Type of aircraft: Airborne Warning and Control System (AWACS). Manufacturer: Boeing.

Maiden flight: 1972.

Use: Military surveillance and command center.

WACS stands for Airborne Warning and Control System. An AWACS is an airplane that is used as a flying radar station and control center. Its jobs are to alert air defenses of incoming enemy aircraft or missiles and to provide a flying opera­tions command center.

Before radar was first fitted to air­craft in the 1940s, pilots had to rely on their eyesight to spot enemy forces. The first planes to use radar in combat were World War II night fighters. In the 1950s, radar was fitted to naval
airplanes and land-based patrol air­planes. They used radar to hunt enemy submarines and detect enemy ships and aircraft. In the 1960s the idea was taken a step further, and this led to AWACS.

U. S. defense planners feared an enemy attack might destroy or damage ground-based radar and communica­tions systems. The answer was to put a radar-based electronic system in a large airplane that could become an “eye in the sky” for commanding officers on the ground.

The U. S. Air Force ordered a conver­sion of a Boeing 707 airliner to become an AWACS. The first of these aircraft came into service in 1977. Named the E-3A Sentry, it looked like a 707 with one very obvious addition: a large,

mushroom-shaped rotodome on top. Inside the rotodome was radar and other electronics equipment. Other electronic gadgetry was packed into the wings, cabin, and tail of the airplane.

AWACS airplanes usually carry a crew of four and up to thirteen elec­tronics warfare specialists. Consoles inside the aircraft display computer – processed data on screens. Missions last eight hours or longer. The aircraft can be refueled in flight by a U. S. Air Force tanker, and crew members can take breaks in the plane’s rest area.

AWACS planes track enemy aircraft and ships and identify friendly forces. They can also listen in to enemy com­munications. Their radar has a range of more than 250 miles (400 kilometers) when tracking low-flying targets. At high altitudes, AWACS can detect a plane or missile at even longer ranges. Information is relayed to military com­manders, battlefield control centers, and even to the president and the secretary of defense. AWACS communications are jam resistant, which means they cannot be blocked by enemy electronic counter­measures. AWACS surveillance operates alongside spy satellites and robot drones, which are also used to gather military information.

The E-3A Sentry is still used by the U. S. Air Force, which had thirty-three AWACS planes as of 2006. Some of these are deployed overseas in combat zones. The AWACS E-3A Sentry is also used by NATO, the British Royal Air Force, and the air forces of France, Chile, and Saudi

TECH’^TALK

THE E-3A SENTRY

The E-3A Sentry is a modified

Boeing 707/320. It has:

• Four Pratt & Whitney turbofan engines.

• A rotodome 30 feet (9 meters) in diameter that rotates at six revolutions per minute in normal operations.

• A cruising speed of 530 miles per hour (853 kilometers per hour).

• An operational height of 29,000 feet (8,840 meters).

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Arabia. The Japanese Air Self-Defense Force uses a Boeing 767 version.

Other types of airplanes are used as AWACS aircraft. The U. S. Navy flies the Grumman E-2 Hawkeye on Airborne Early Warning (AEW) missions from its aircraft carriers. The Russians converted the Ilyushin Il-76 airliner into an AWACS airplane. Israel has its own AWACS system, without the big rotodome, in the Gulfstream G-550 air­plane. The Royal Australian Air Force uses the Wedgetail, an AEW aircraft based on the Boeing 737.