Category FLIGHT and M ОТІOIM

lying boats and sea­planes are airplanes that can take off and land on water. A seaplane, or float­plane, looks like a regular air­plane. Instead of landing gear with wheels, however, it has a pair of canoe-shaped floats to keep the seaplane afloat.

A flying boat is a type of sea­plane, but it has a boat-shaped hull, or body, which rests in the water. It has floats fitted on struts beneath the wings to provide extra balance. An amphibian is a seaplane that also has wheels for landing at an airfield.

Most flying boats and seaplanes are high-winged designs, sometimes using a “gull-wing” V-shape. The shape places the engines as high above the water as possible, clear of spray. To take off and land, the aircraft skim over the water.

The Age of Water-Based Aircraft

For a time, seaplanes were the fastest planes in the world. In 1931 the British Supermarine S6B held the world’s air speed record, at 406.9 miles per hour (654.8 kilometers per hour). Small sea­planes were carried on battleships for reconnaissance missions. The seaplane was launched by catapult; on return, it landed on the ocean’s surface and was lifted up out of the water by a crane on
the ship. Today, helicopters do the same job on many naval ships.

A flying boat was bigger than a reg­ular seaplane-some were very large. In some situations it was safer than a land plane because, in an emergency, it could land on the ocean and float until rescue arrived. Flying boats were very popular in the 1930s for carrying passengers. The big cabin of a flying boat offered a high standard of luxury to passengers, who could go ashore when the plane landed, spend a night in a hotel, and resume their journey next day.

In World War II (1939-1945), flying boats were used for ocean patrols and for hunting enemy submarines. They also pioneered new air routes across the Atlantic and Pacific oceans. After World War II, land planes got faster. More

airports were built in cities-and it was between cities that most air passengers wanted to travel. By 1950, the age of the flying boat had ended.

Currently, the F-15 Eagle is the fastest U. S. jet fighter. At around 1,800 miles per hour (2,900 kilometers per hour), it is slightly slower than the Russian MiG-25, which flies at 2,115 miles per hour (3,403 kilometers per hour). It is unlikely that
fighter plane speeds will increase much beyond this in the next twenty or thirty years. Instead, the military wants to make high-speed airplanes more flexi­ble. Air forces will use a new generation of drones-robot planes that will fly the same combat missions as a piloted air­plane, but at far lower cost.

About 80 percent of the useful work­ing life of a modern combat airplane is given over to pilot training. It is very expensive to train jet pilots, so why not give the most dangerous jobs to a robot?

An unmanned combat air vehicle (UCAV) can be made half the size of a conventional airplane, so it is cheaper, harder to detect, and more difficult to shoot down. Since no pilot training is required, a drone uses expensive fuel only on actual combat missions.

Combat drones are expected to carry miniaturized weapons with the same destructive power as the bombs and mis­siles of today, but the weapons will be only one-tenth the weight. The U. S. Air Force’s experimental X-45A is already potent enough to destroy a truck from

35,0 feet (10,800 meters). In the future, the military could deploy squadrons of unmanned airplanes, including microdrones—aircraft no big­ger than birds that are armed with mini­weapons of awesome destructive power.

Military airplanes are so expensive that, in the future, the number of new designs that actually go into production will be very few. One airframe will be adapted to carry out many tasks. A highly complex, multirole combat plane, the F-35 Joint Strike Fighter, is a good example. The F-35 has a lift-fan STOVL (short takeoff vertical landing) capabili­ty, so it can operate at sea or from small airfields. Its advanced stealth design makes it hard to detect on radar. Over the next ten to fifteen years, this one aircraft will replace several existing frontline fighters and strike aircraft, not just in the U. S. armed forces, but in other forces around the world. A number of nations—including Norway, Australia, Canada, the Netherlands, and Denmark—

SCRAMJETS

Scramjets could be the supersonic transports of the middle twenty – first century. In 2004, a hypersonic, unmanned plane raced into the record books at 7,000 miles per hour (11,263 kilometers per hour). NASA’s X-43A ”scramjet” (short for "super­sonic combustion ramjet") has an air-breathing engine similar to that proposed for HyperSoar. The X-43A was launched from a B-52 bomber and then boosted by a Pegasus rock­et until its own engine fired. Its scramjet engine, which (unlike a tur­bine engine) has no spinning blades, can send the X-43A accelerating to almost ten times the speed of sound at an altitude of approximately

110,0 feet (33,530 meters).

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have helped to develop the F-35, which is manufactured by the Lockheed Martin Corporation, Northrop Grumman, and British Aerospace.

SEE ALSO:

• Aerospace Manufacturing Industry • Aircraft, Commercial

• Aircraft, Experimental • Aircraft, Military • Aircraft Design • Fuel

• Supersonic Flight

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SATELLITES

In the twenty – first century, the regular launches of commercial satellites for the purposes of tele­communications and navigation are an everyday occurrence. These uses for satellites will continue to grow over the next decades.

As every Inter­net user knows, it is now possible to call up a satellite image of your neighborhood at the click of a mouse. Satellite images also are used for scientific purposes, such as scanning Earth from orbital spacecraft for signs of global warming or even tracking migrat­ing caribou. NASA and other space agencies will continue to use scientific satellites to gain knowledge. In the near future, for example, MicroSCOPE will orbit Earth to test a scientific theory related to gravity called the Equivalence Principle. This satellite will survey Earth’s surface to provide new data on erosion, deforestation, land use, fuel reserves, and other environmental issues. Jason 2, to be launched by European agencies in partnership with the United States, will study the oceans’ currents and sea levels, which will help scientists understand and pre­dict changes in the world’s climate.

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prelude to a mission to Mars. No astronauts have walked on the Moon since the Apollo program ended. With its Constellation Program, however, NASA is planning a Moon landing before 2020. The near future also may see the con­struction of a permanent base on the Moon. One day, there could even be a lunar “factory” making rocket fuel from the Moon’s soil.

From the Moon, spacecraft could voyage to Mars. Ever since NASA’s Mariner 4 space­craft flew by Mars in 1965, scientists have been eager to explore Earth’s neighboring planet. Future missions by robot spacecraft will include the Mars Science Laboratory, scheduled for 2009. It will explore the surface of Mars for a full Martian year (which lasts nearly two years in Earth days). There are plans for robot craft to land, take samples of Martian soil, and return to Earth. A manned landing on Mars could happen before 2040. In the meantime, new orbital probes such as the Mars Reconnaissance Orbiter, launched in 2005, will scan the planet and look for more evi­dence of water on its surface, which would make a manned landing more feasible.

GPS has three parts, or segments. They are the Space Segment, the Control Segment, and the User Segment.

Satellites form the Space Segment. GPS satellites are divided into six groups of four. Each group is in a different orbit. The satellites orbit at a height of 12,600 miles (about 20,270 kilometers). At this height, they take 12 hours to cir­cle Earth, so they go around the world twice in one day. The satellites travel at a speed of

О The satellites in the GPS occupy six orbital planes 60 degrees apart, all tilted at 55 degrees to the equator. Receivers on Earth determine their positions by picking up signals from four satellites.

ATOMIC CLOCKS

Each GPS satellite carries three or four atomic clocks, depending on which type of satellite it is. Amazingly, the clocks carried by GPS satellites are accurate to about 1 second in 300,000 years! Only one atomic clock is used at a time; the others are there as backups. If a clock fails for any reason, a backup takes its place.

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about 7,000 miles per hour (11,260 kilo­meters per hour). Electric power for the clocks, onboard computer, and radio equipment is generated by solar panels. As the satellites orbit Earth, their solar panels turn automatically to face the Sun, while the radio antennae keep pointing at Earth.

The Control Segment on Earth runs the system. Monitor stations check the orbit, position, and clock time of every satellite and send all the information to the Master Control Station at a U. S. Air Force base in Colorado. This information is compared with the information trans­mitted by the satellites, and any errors are corrected.

The User Segment includes all the GPS receivers that use the system. The receiver gets three pieces of information from the satellites: a code that identifies each satellite and two packets of data called ephemeris data and almanac data. Ephemeris data tell a receiver where each satellite should be. Almanac data tell the receiver the date, time, and whether or not the satellite is work­ing correctly.

The rotor of a helicopter serves as both wings and propeller. Lift is produced by changes in air pressure caused by the spinning blades of the rotor. As a blade moves, air flows faster over its curved upper surface than over its flat lower surface. This results in reduced air pres­sure above the blade; the difference in air pressure produces lift.

The helicopter pilot can control the amount of lift by altering the angle of the rotor blade. If the blade is tilted so that more air presses up against the bot­tom of the blade, the air pressure beneath it increases, and so does the helicopter’s lift.

A helicopter can fly straight up and forward or backward. It can hover, fly straight down, and fly sideways, but it cannot glide. A helicopter pilot can never let go of the controls-just to hover requires the pilot to make con­stant tiny corrections to maintain the correct position.

In spite of these failures, Hughes turned his manufacturing company into a lead­ing force in the aviation field after World War II. One division made helicopters. Another eventually made satellites. Over the years, the company produced more than one-third of all the satellites being used by businesses. Eventually, the company was broken up, and its divisions were sold to other corporations.

Од 1972 issue of Time magazine featured the reclusive Howard Hughes on its cover. There were rumors that his mind and appearance deteriorated in his later years, but there were no photo­graphs of him.

Hughes also became involved in the airline industry. In 1939, he bought the majority of Trans­World Airlines (TWA), which he hoped to build into the world’s leading airline. As part of that effort, he made an agreement with Lockheed to build a new passenger plane. The result-the Constellation-was an innovative new plane.

Hughes’s effort to build the airline clashed with the ambi­tions of Juan Trippe, the head of Pan American World Airways.

Senator Owen Brewster of Maine, an ally of Trippe’s, called Hughes to testify before a Senate committee. Under harsh criticism, Hughes counter­attacked by revealing the senator’s con­nections with Pan Am. Hughes was never charged with any wrongdoing. He later funded the victorious campaign of the man who defeated Brewster in his bid for reelection.

Hughes’s troubles with the govern­ment did not end, however. Federal officials informed him it was a conflict of interest for him to own both TWA and an aircraft manufacturing company. Eventually, Hughes had to sell his inter­est in TWA.

Always shy and eccentric, Hughes lived as a recluse from the 1960s on. Obsessed with living in a completely germ-free environment, he ate almost no food, and took many drugs. These actions destroyed his health. He died in 1976-a lonely, often ridiculed, and vastly wealthy old man.

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SEE ALSO:

• Aerospace Manufacturing

Industry • Aircraft Design

• Aircraft, Experimental • Satellite

• Flying Boat and Seaplane

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Insects are among the animals on Earth which have wings (the others are bats and birds). About 400 mil­lion years ago, the first animals to fly included insects. There are about 1 mil­lion species of insects—three times as many as all the other animal species in the world. The most common features of insects are their small size, their crawl­ing motion, and their ability to fly.

Wings and Other Parts

Insects have small, light bodies. The body of an adult insect has three parts: the head, the thorax, and the abdomen. The thorax is the “engine room” of the animal. An insect’s wings are attached to the middle and rear segments of the thorax. The wings are worked by two sets of powerful muscles, which make the wings beat up and down and also twist. Muscles attached to the base of each wing control the direction of flight, allowing an insect to change direction, fly backward and forward, or hover in midair like a helicopter.

Flies have two wings, fixed to the center body section or thorax. Other insects have four wings in two pairs. Examples of four-winged insects are butterflies, moths, dragonflies, bees, and wasps. In a four-winged insect, the two wings on one side of the body often beat together as if they were one wing. In some insects, the wings overlap slightly, while in others the wings are locked together by a system of hooks or hairs.

Many insects have wings in their adult state, although many flying insects (dragonflies, for example) are flightless as juveniles. The wings of a young insect start to grow as tiny pads, visible only through a microscope, or sometimes (as in caterpillars), they are inside the body.

When the young insect molts (sheds its skin as it grows larger), the wing pads grow. After the last molt, the pads become fully formed wings. This change, or metamorphosis, is seen to startling effect in moths and butterflies.

The adult emerges from the chrysalis with its wings damp and still folded. As the wings dry and are stiffened by blood flowing through the veins inside them, they unfold and often reveal brilliant colors.

In beetles, the front wings have become hard covers called elytra. The elytra are folded over the rear wings, until the beetle starts to fly. Then they swing outward, like airplane wings. The rear wings do the actual flying.

Other insects have no wings at all or only weak vestiges (remains) of wings that are no use for flying. Most ants, for example, are wingless. Only males and female queens have wings, which are used to fly from the nest during their mating flight. The males die after mat­ing, and the queens spend the rest of their lives underground.

Aircraft and spacecraft are not the only vehicles that make use of jet power. Some battle tanks and fast warships are propelled by gas turbines. It is not the jet thrust of the engine that propels these vehicles, however. The Abrams tank’s gas turbine engine drives its tracks. A warship’s gas turbine drives its propellers.

Other vehicles do use jet thrust to accelerate to very high speeds. The fastest cars in the world are powered by thrust. The problems designers face in
creating thrust-powered cars are similar to those faced by aircraft designers. The shape of the car is very important, because drag must be cut to a minimum.

The world’s fastest car has traveled faster than the speed of sound. On October 15, 1997, Thrust SSC, driven by British fighter pilot Andy Green, set a land speed record of 763 miles per hour (1,228 kilometers per hour) in the Black Rock Desert, Nevada. It was powered by two Rolls-Royce Spey fighter engines, which, together, were more powerful than 150 Indy racecars.

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SEE ALSO:

• Engine • Force • Laws of

Motion • Rocket • Whittle, Frank

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Date of birth: May 23, 1848.

Place of birth: Anklam, Germany.

Died: August 10, 1896.

Major contribution: Researched and wrote about many principles of aero­dynamics and aeronautics; first person photographed flying a successful heavier-than-air aircraft.

tto Lilienthal became attracted to the idea of flying as a teenager. In his first attempts at flying, he tried to mimic the method used by birds. Lilienthal built two pairs of 6.5-foot-long (1.9-meter-long) wings. He strapped one pair on his brother’s arms and the second pair on himself. The two ran down a hill flapping the wings, hoping to take off into the air. The experiment failed, but Lilienthal remained committed to flying.

In 1870, Lilienthal graduated with a degree in mechanical engineering from the University of Berlin, Germany. While heading a factory that made engines, he devoted his spare time to studying the flight of birds.

In 1891, Lilienthal built his first glid­er. The frame was made of willow wood covered by cotton fabric. The wings were 25 feet (7.6 meters) long from tip to tip. Lilienthal bounced off a springboard to launch himself into the air. On the first attempt, he traveled only a few feet. Lilienthal made repeated experiments, increasing the height of the springboard and then shortening the wingspan.

Eventually, he glided as far as 80 feet (24 meters).

Over the next few years, Lilienthal continued tinkering with gliders. From 1891 to 1896 he took more than 2,000 glider flights. Lilienthal tried covering both sides of the wings and adjusting wingspan. Most of his designs were monoplanes, with single wings, but some were biplanes. In most of his air­craft, Lilienthal stood in a harness between the wings, with his torso above the wings and his legs below. Once aloft, he maneuvered the glider by shifting his weight from one side to another or by leaning to the front or the back.

AN IMPORTANT PUBLICATION

In 1889, Otto Lilienthal published a book summarizing his research into how birds fly. Called Bird Flight as the Basis of Aviation, it was a brilliant work for its time. Lilienthal conclud­ed that the curved shape of birds’ wings was the secret to their flying ability. He proposed that a flat sur­face would offer less wind resistance and prevent lift. He also calculated how long wings would have to be to carry a human into flight.

Although effective, the technique was difficult and required great strength. Lilienthal tried adding devices to make it easier to guide the glider.

By 1894, Lilienthal had decided that he needed a better launching area. He mounded dirt into a hill and built a shed on top, where he stored his equipment. The hill allowed Lilienthal to launch no matter which way the wind was blow – ing—he could simply run down the appropriate side of the hill. He always chose to run into the wind to get the needed lift.

Lilienthal was able to glide more than 150 feet (46 meters) from his new launching site, but he wanted to go even farther. As a result, he began launching himself from some higher hills near Berlin. On one trip, Lilienthal traveled 1,150 feet (350 meters).

Continued tests led to a fatal disaster. On August 9, 1896, Lilienthal took a glider flight in the midst of heavy wind gusts. One gust caught the glider and sent it crashing to the ground from 50 feet (15 meters) up. Lilienthal broke his back and died the next day.

Lilienthal’s work in aviation was of great importance. His writings influ­enced others interested in flying, including Orville and Wilbur Wright. Photographs taken of his glider flights inspired many early aviation pioneers by showing that a man could, indeed, build and fly a heavier-than-air aircraft.

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SEE ALSO:

• Aerodynamics • Aeronautics

• Aircraft Design • Glider • Lift

and Drag

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Missiles that spend most of their flight falling through the air without power are called ballistic missiles. A rocket launches them high in the air, or even into space, and then gravity pulls them back down to the ground again. A track­ing system finds the target and locks onto it. The tracking system gives the target’s location to the missile’s guid­ance system, which then works out the flight path the missile needs to follow. The guidance system commands the flight system to steer the missile, usual­ly by moving fins on the missile’s body.

Small ballistic missiles are mounted on mobile launchers that can be moved from place to place. The biggest ballistic missiles—intercontinental ballistic mis­siles (ICBMs)-can fly more than 3,300 miles (5,300 kilometers) from one conti­nent to another. These missiles are too big and heavy to be moved around by trucks, but they would be easy to attack if they stood out in the open. One way to hide large missiles from enemies is to keep them in launch tubes, called silos, buried in the ground. As missiles have become more accurate and more power­ful, however, silos provide less protec­tion. Another way to protect missiles

from enemy attack is to put them in nuclear submarines, which can stay sub­merged in the ocean for weeks at a time.

he National Aeronautics and Space Administration (NASA) is the U. S. national space agency. It was formed in 1958 for advanced aero­nautics research and space exploration. NASA is a federally funded organiza­tion, employing thousands of engineers, scientists, and professionals in aerospace research. Its work includes developing new airplanes and spacecraft and testing new technologies.

NASA has been associated with many of the most dramatic and historic episodes in the history of spaceflight-it achieved worldwide recognition in the 1960s when it sent astronauts to the Moon. NASA’s work continues into the twenty-first century, with manned spaceflights and with space probes that explore the Solar System. It is the world’s leading space agency, ahead of the Russian federal space agency and the European space agency.

NASA scientists and engineers are also engaged in research projects concerning transportation and the envi­ronment. Images taken from NASA sources, such as space telescopes and probes, have excited the imaginations of people around the world. NASA’s exten­sive educational and media programs provide information about space and space technology.

NACA

The predecessor to NASA was known as the National Advisory Committee for

Aeronautics (NACA), which was founded in 1915. This body was responsible for important early research into airplane flight, using research airplanes and wind tunnels. By modern standards NACA was small-in 1938 it had a staff of just over 400 people.

After World War II (1939-1945), NACA expanded its activities into the realm of supersonic flight, working closely with the U. S. Air Force on the record-breaking X-1 airplane and other projects. In the late 1940s, the Department of Defense urged scientists to work with the military on missile experiments. At the same time, scientists were pressing for rockets to be sent into space for research. President Dwight D. Eisenhower approved a plan to launch a science satellite as part of the International Geophysical Year, sched­uled for July 1957 to December 1958. The chosen rocket vehicle for the satel­lite launch was the Naval Research Laboratory’s Vanguard rocket.

The Vanguard Project was under­funded and slow to get off the ground. The United States was shocked when, in October 1957, news broke that the Soviet Union had beaten America into space by launching the world’s first arti­ficial satellite, Sputnik 1. Many people in the United States became concerned that there was a widening gap between Soviet and U. S. space science. American scientists quickly responded to the chal­lenge, launching the nation’s first satel­lite, Explorer 1, in January 1958. Despite this achievement, however, there were
calls for a new agency to drive forward the national effort in the “space race.”

In 1919, the forerunner of the modern parachute was tested in the United States by a group of jumpers, including James Floyd Smith, Leo Stevens, and Leslie Irvin. The new parachute had a circular canopy and a smaller parachute called a pilot chute. Both parachutes and their lines were folded and stowed in a cloth pack. The pack was held closed by three metal pins attached to a wire rip­cord. When the jumper tugged a handle on the harness, the ripcord ripped the pins free, and the pack opened. The pilot chute flew out, acted as a brake, and pulled out the main canopy. On April 28, 1919, Leslie Irvin tested the parachute after jumping out of a plane over McCook Field in Ohio. In 1922, came the first use of a parachute in an emergency when an American military pilot, Lieutenant Harold Harris, bailed out of a test plane over North Dayton, Ohio. Throughout the 1920s, barnstormers and show jumpers made parachute jumps to entertain crowds at flying shows.

Most jumps were from low level. Doctors warned that parachuting from great heights, or falling at high speed before the parachute opened, would kill the jumper. In fact, such fears were proved wrong. In 1945, Lieutenant Colonel William Lovelace jumped from a B-17 bomber at a height of 40,000 feet (12,190 meters). Although he wore breathing apparatus, Lovelace became unconscious, but his parachute opened, and he landed safely.