Category FLIGHT and M ОТІOIM

Business boomed as World War II pro­gressed. At peak production in 1944, Boeing’s Seattle plant rolled out sixteen new planes in twenty-four hours. During World War II, B-17s flew day­light bombing raids, relying on their armament of thirteen machine guns for defense against enemy fighters.

The B-17 was succeeded in 1942 by the B-29. The B-29 was twice as heavy; it had a top speed of 358 miles per hour (576 kilometers per hour) and a range of 3,250 miles (5,230 kilometers). The manufacture of the B-29 was spread all around the nation. Thousands of subcontractors supplied the airplane’s components to four production plants: Boeing at Renton, Washington, and Wichita, Kansas; Bell at Marietta, Georgia; and Martin at Omaha, Nebraska.

From the B-17, Boeing developed the 307 Stratoliner (1938), the first pressurized airliner, which seated thirty – three passengers. The B-29 gave rise to a cargo plane, the 367 (1944), and a passenger carrier, the 377 Stratocruiser.

This was Boeing’s last, big, piston – engine airliner. In the 1940s and early 1950s, the 377 carried 117 passengers from New York City to London at 340 miles per hour (547 kilometers per hour).

Instruments in an aircraft’s cock­pit show the pilot what is hap­pening to the aircraft and how well it is flying. The instruments are especially important when a pilot cannot see the ground because of cloud, fog, or dark­ness. They enable a pilot to keep an aircraft flying safely in the right direction. The instruments also can warn pilots of dangers, such as fire in an engine or flying too close to the ground.

Glass Cockpits

Modern cockpits often have several screens, like computer screens, which combine the functions of many separate instruments. This kind of cockpit is called a glass cockpit.

There are three types of screens in a glass cockpit. The first is the primary
flight display, which shows the airspeed, altitude, heading, and vertical speed. There is a primary flight display in front of each pilot.

The next screen is the navigation display, which shows the aircraft’s posi­tion and course. The picture from the aircraft’s weather radar also can be

TECH^TALK

There are seven basic flight instru­ments in an airplane:

• Airspeed indicator shows an aircraft’s speed compared to the surrounding air.

• Altimeter shows an aircraft’s height above sea level, or altitude.

• Attitude indicator shows an aircraft’s attitude (the way it is pointing) compared to the horizon.

• Magnetic compass shows an aircraft’s heading (direction).

• Heading indicator also shows heading but works in a different way from the magnetic compass.

• Turn and bank indicator shows if an aircraft is turning correctly.

• Vertical speed indicator shows how fast an aircraft is climbing or descending.

The magnetic compass works by sensing the direction of Earth’s mag­netic field. It works fine in steady flight, but it can be unreliable if the plane is climbing, diving, or turning.

The heading indicator (which is based on a gyroscope) is used to double-check it.

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shown on this screen. A small business jet might have one navigation display in the middle. A larger airliner may have a separate navigation display in front of each pilot.

The third type of screen is linked to the engine indicating and crew alerting system (EICAS). It shows engine infor­mation and emergency warnings. In addition, an aircraft’s flight computer has its own small screens.

A glass cockpit can greatly reduce the number of instruments and controls. The glass cockpit of the Boeing 747-400 has 365 instruments and switches – about 600 fewer than the cockpits in earlier 747s. A glass cockpit also has a basic set of old-style instruments to provide an emergency backup if the cockpit screens fail.

Glass cockpits have proved to be so reliable and effective that spacecraft now have them as well. The Space Shuttle and Soyuz spacecraft are fitted with their own glass cockpits.

BOAC showed its loyalty to the Comet by ordering Comet 4s in 1955, but the

LESSONS LEARNED

Airplane manufacturers learned les­sons from the Comet. All modern airplanes are very strongly built. Their structures (body, wings, tailplane, and everything else) are tested extensively to see how long it takes for cracks to appear. Further tests are made during an aircraft’s working life, to check for any signs of structural failure (some­times called metal fatigue). If inspec­tions show even minute cracks in any part of the structure, airplanes are taken out of service for repair, or they are permanently retired.

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company had to wait until 1958 for these new airplanes to be delivered. That year, Comet 4s began operating passen­ger flights between London and New York. The Comet 4 was bigger than the Comet 1; it was 18.5 feet (5.6 meters) longer and could seat eighty to 100 pas­sengers. Its Rolls-Royce Avon engines were twice as powerful as the De Havilland Ghost engines used in the Comet 1. The Comet 4 cruised at 503 miles per hour (809 kilometers per hour) at 42,000 feet (12,800 meters) and had a longer range than the original Comet. It also had a strengthened fuselage and stronger windows. The Comet 4 proved to be a perfectly safe and easy airplane to fly and travel in.

By this time, however, airlines— especially large airlines in the United States—were lining up to buy new, U. S.-built jet airliners. The Comet had lost its lead in world jet travel to the U. S. Boeing 707 and the Douglas DC-8. These airplanes were faster and carried more passengers than the Comet, and they sold in much greater numbers.

The Comet, as the world’s first jet airliner, never achieved the success that its designers had hoped for. The Comet airframe was later used as the basis for the British Aerospace Nimrod maritime patrol aircraft, first flown in 1967.

SEE ALSO:

• Aerospace Manufacturing

Industry • Aircraft, Commercial

• Aircraft Design • Jet and Jet

Power • Materials and Structures

Flying takes a lot of energy. When a bird flies, it uses about fifteen times more energy than when it is still. The fuel that supplies this energy is the bird’s food, which is stored as fat until it is needed.

When a bird takes off and flies, it needs the chemical energy stored in its fatty fuel. The energy is released by chemical reactions that use oxygen from the air. A lot of oxygen is needed to keep

a bird’s muscles supplied with enough energy to keep flying.

Airplanes and rockets have energy needs similar to those of a bird. They carry energy stored in their fuel, and they have to combine the fuel with oxy­gen to burn it and release the energy. When a jet plane or rocket takes off, chemical energy in the fuel changes to heat energy in the engines. Heat energy changes to the kinetic energy of the hot gas that shoots out of the engines.

Other Forms of Flight Power

There are other ways than using jet fuel to obtain the energy needed for flight. There are electric airplanes powered by propellers driven by electric motors. The electricity is produced by solar cells on top of the wings. Solar cells change solar energy into electrical energy.

There have been experimental nuclear-powered aircraft, too. In the 1950s, nuclear-powered military planes seemed attractive because they could stay in the air for weeks or months. Nuclear-powered jet engines were built, and at least one nuclear-powered air­craft did fly. These planes never went into production, however. It proved to be too hard to protect the crew from the dangerous radiation produced by the fuel. If one of these planes had crashed, it also could have spilled radioactive fuel over a wide area.

In the 1920s, the German firm of Dornier built the Whale, which set the pattern for later passenger flying boats. It had four engines set on top of the wing and a boat-shaped hull, with airfoil-shaped sponsons (float-like attachments to the hull) that kept the craft stable on water.

The Whale cruised at 112 miles per hour (180 kilometers per hour) for a distance of 1,243 miles (2,000 kilometers) and could carry up to nineteen passengers. Whales and the bigger Super Whales made many record-breaking flights and opened up new commercial services, such as flights from Germany to Brazil.

Pan American Airways started the first regular mail and passenger service across the Pacific Ocean in 1935, using the Martin 130 China Clipper, a flying boat. The Clipper could carry forty-eight passengers on daytime flights and eight­een passengers in a night sleeper layout. Britain also built flying boats for long- haul routes: The Short Empire flying boats (1936), for instance, flew to Africa and India.

Flying Boats at War

During World War II, navies of warring nations used flying boats and other sea­planes to attack shipping and patrol supply routes. The British built the Short Sunderland, a heavily armed patrol flying boat, to hunt Nazi submarines in the Atlantic Ocean. The Sunderland remained in service until 1959.

Probably the most famous seagoing airplane of World War II was the U. S. PBY Catalina. Built by Consolidated and first flown on March 28, 1935, the twin – engine Catalina carried a crew of up to nine people. It had a cruising speed of 117 miles per hour (188 kilometers per hour) and a range of 2,500 miles (4,023 kilometers). The Catalina offered greater range and load-carrying capacity than

earlier flying boats. It flew with the British, Canadian, and Australian forces and also was built in Russia.

As well as flying patrol and bombing missions, Catalinas rescued many pilots whose airplanes had crashed into the ocean, dropping lifeboats into the water or landing to pick up fliers from the water. Most Catalinas were amphibious airplanes-they had wheels and so could land on a runway, too. Consolidated also built the larger, four-engine PB2Y Coronado, a flying boat bomber that saw service during World War II.

Space engineers are now interested in developing cheaper launch systems for satellites and space tourists. One possi­bility is a space elevator. This idea, basi­cally a giant tower reaching into space, was first put forward by the Russian sci­entist Konstantin Tsiolkovsky at the beginning of the twentieth century. It was later described by the science fiction writer, Arthur C. Clarke. The space eleva­tor would consist of a tower, some 31 miles (50 kilometers) high, with a cable

C NASA’s Advanced Projects Office has put together plans for a space elevator, an idea that has previously been explored only in science fiction.

linking the top of the tower to an orbital space station. Passengers and cargo pay­loads would be transported into space along magnetic tracks fixed to the cable, riding in magnetically levitated (or maglev) vehicles.

Away from the billion-dollar nation­al and international space programs, individuals are planning space tourism in privately sponsored spacecraft. The pioneer in this field of spaceflight was SpaceShipOne, first flown in June 2004.

Such opportunities will increase the popularity of space tourism.

GPS was originally intended only for military use, but a civilian service was added. The civilian service was less pre­cise-in fact, errors were deliberately included to make it even less accurate so that enemy military forces could not make use of it. The civilian service offered what was called Selective

О GPS is used aboard military aircraft for pin­pointing targets to be destroyed. Soldiers in the field use handheld survival radios equipped with GPS for search and rescue missions.

О The GPS IIR satellites were designed to last longer and be more accurate than earlier GPS equipment. GPS technology is constantly improving.

Availability, a system that enabled receivers to calculate their position only to within about 300 feet (100 meters). In 2000, President Bill Clinton ordered the Selective Availability system to be turned off. The accuracy of the civilian GPS service was immediately improved.

Most receivers are now designed to provide extra features. If they are in a moving vehicle, such as an aircraft, they compare a series of positions and use them to calculate the vehicle’s speed and direction. If this information is com­bined with a digital map, GPS can be used for navigation. Professional map – makers and surveyors also use GPS to produce very accurate maps. Farmers even may use GPS to map their fields and calculate how much fertilizer or weed killer is needed in different places.

The single-rotor helicopter has one large rotor, usually mounted toward the front of the body and above the passenger compartment. A smaller rotor is attached to the tail of the helicopter.

The main rotor may have between two and eight blades. The tail rotor can have two, twelve, or more blades. It is mount­ed vertically on the side of the tail and is therefore at right angles to the main rotor. The tail rotor provides stability, acting against the tendency of the heli­copter to spin around in the opposite direction of the main rotor blades. This spin force is known as torque.

The tail rotor may be shrouded, or enclosed in a cover-it is then called a fenestron. This is quieter and safer, but less efficient. A tail rotor can use up to 5 percent of the engine’s power without helping the helicopter fly upward or for­ward. One way of improving efficiency is to angle the vertical stabilizer so that it counteracts the torque without taking power from the engine. Helicopter pilots call this “slipstreaming.”

For their size, many insects fly extreme­ly quickly. Most insect flights are short hops during food-gathering expeditions. Honeybees, for example, buzz from flower to flower, using a complex navi­gation system to find their way between the nest or hive and the flowers. They have a system of body language to tell other bees where to find the flowers. Flying is energetic, and few insects can sustain such a high output of energy for long. A honeybee usually flies for up to 15 minutes before it has to feed and refuel its muscles.

A few insects make long migratory flights. The North American monarch butterfly is a good example. It flies south in large groups to escape the northern winter, returning the following year. Migrating butterflies can fly for 100 miles (160 kilometers) without stopping for food. Another long-distance flier, though an unwelcome one, is the desert locust of Africa and Asia. A swarm of locusts may contain billions of insects. Locusts can fly hundreds of miles with­out feeding before they finally land and ravenously eat every blade of grass or clear fields of their crops.

FAST WINGS

The fastest flying insects are dragon­flies. Over a short distance, they have a top speed of about 60 miles (96 kilometers) per hour. The fastest wing beat ever recorded for an insect was that of a tiny midge: nearly

65,0 beats per minute. Most insects are much slower. A housefly beats its wings about 200 times every second-a mere 12,000 times a minute! Butterflies have the slowest wing beats of any insect, at around 500 times a minute.

After World War II, U. S. scientists began rocket experiments at the White Sands military facility in New Mexico. As the United States developed its missile program, a new launch site was needed. In 1949, President Harry S. Truman

authorized a firing range at Cape Canaveral in Florida.

The area was thinly populat­ed and therefore an ideal site for testing secret and some­times unpredictable rockets.

Cape Canaveral also offered a fine, clear climate and access to thousands of square miles of the Atlantic Ocean.

Cape Canaveral attracted more media and popular interest after the United States launched its first satel­lites, Vanguard and Explorer, in 1957 and 1958. Despite these successes, U. S. public opinion was critical because the Soviet Union had taken the lead in the “space race.”

The demand for more action led to the formation of NASA in October 1958, and Cape Canaveral became a major launch base for NASA as well as for the U. S. military.

The United States in Space U. S. space exploration opened a new chapter in May 1961, when President John F. Kennedy announced the United States would send astronauts to the Moon before the end of the 1960s. On July 1, 1962, Cape Canaveral became NASA’s new Launch Operations Center. The first director of the center was Dr. Kurt H. Debus, a rocket scientist. The Launch Operations Center was renamed the John F. Kennedy Space Center in December 1963, a month after the pres­
ident’s assassination. (Cape Canaveral was renamed Cape Kennedy that year, but it reverted to its old name in 1973.)

The Apollo Program was now under­way. So vast was this project, and so big was the three-stage rocket planned to launch Apollo spacecraft to the Moon, that NASA decided to build a larger launch facility. Several sites-including ones in Hawaii, Texas, California, and the Caribbean-were considered before NASA and the Department of Defense chose Merritt Island, west of Cape

Apollo Moon missions, a huge con­struction program was undertaken with the help of the U. S. Army Corps of Engineers. A new launch center, named Launch Complex 39 (LC-39), included the vast Vehicle Assembly Building (VAB).

With the Mercury and Gemini spaceflights of the 1960s, interest in spaceflight grew. Each blastoff attract­ed excited media coverage. Kennedy Space Center became the center of world attention in 1969, when the Apollo 11 mission blasted off from LC-39 for its historic trip to the Moon, honoring President Kennedy’s pledge.