Category FLIGHT and M ОТІOIM

Date of birth: December 25, 1642. Place of birth: Woolsthorpe, England. Died: March 20, 1727.

Major contribution: First formulated the idea of gravity; expressed three key laws of motion; invented calculus, a branch of mathematics.

Awards: Named a Fellow and later President of the Royal Society; Order of Knighthood.

saac Newton had a difficult child­hood. His father died a few months before he was born. Newton was a sickly child who was not expected to live. When Newton was two, his mother remarried, and his stepfather sent him away to live with other relatives. Only when the stepfather died was Newton reunited with his mother.

Newton began studying at Trinity College, Cambridge, England, in 1661. He dedicated himself to new, emerging ideas in science and mathematics. Much of his study of the new science was done on his own and appeared only in his private notebooks. In 1665 Newton graduated from Trinity College and over the next two years, he reached conclusions that formed the basis of his later work.

In 1667, Newton returned to Cambridge as a professor. Using a pair of prisms, he broke white light into its different colors-those we see in a rainbow. Through this work, Newton proved that light is not a simple structure but a complex one. He also began to develop the

О Isaac Newton is one of the most important scientific figures in the history of the world. His view of physics prevailed until they were modified by Albert Einstein’s ideas in the early 1900s.

ideas that would become calculus, an advanced form of mathematics that makes it possible to describe the move­ments of objects.

Newton began to think about the orbit of objects around planets. He wrote an essay called On Motion in 1684 and expanded his ideas three years later in his masterwork Philosophiae Naturalis Principia Mathematica. With this work Newton established his three laws of motion and his theory of universal gravitation. Newton’s ideas gained wide acceptance fairly quickly, and his theories are the basis of much of modern physics.

In 1696 Newton was named Warden of the Royal Mint, which oversees the making of coins. He kept his professor­ship at Cambridge for a few more years, but most of his later life was spent in London. In 1704, Newton finally pub­lished a work about sight, light, and color entitled Opticks.

Although he did little new work in later years, Newton remained an impor­tant figure in the sciences. He became President of the Royal Society in 1703. In that role he helped sponsor the work of younger scientists who quickly rose to dominate the scientific community in England, further helping to spread Newton’s ideas. Two years later, Newton became the first scientist ever to be knighted by a British monarch.

Newton’s later life was marred by a major controversy. He had devised the basics of calculus back in the 1660s but had never published a detailed

NEWTON’S CANNON

Hundreds of years before it actually happened, Newton understood that a human-made object could orbit Earth, just as the Moon did. Imagine, he said, a mountain so tall that it extended above Earth’s atmosphere. Now imagine placing a cannon atop the mountain’s peak and firing a cannonball on a hori­zontal path. A powerful enough cannon could fire the ball so fast that it would never fall. At the same time, gravity would bend its path toward Earth. Never falling and never escaping Earth’s gravity, Newton theorized, the cannonball would orbit the planet indefinitely.

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description. In 1684, the German math­ematician Gottfried Wilhelm Leibniz published his work on calculus and gained renown as the inventor of a new system. Newton began a running battle with Leibniz that was carried out in print. Both men tarnished their names with their bitter attacks on one another. Newton died at the age of eighty-four.

SEE ALSO:

• Gravity • Laws of Motion

• Momentum • Satellite

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itch, roll, and yaw are the three ways in which aircraft and space­craft can change their direction of flight. Pitch, roll, and yaw are rotations. When something rotates, it turns around an imaginary line called an axis.

Defining Pitch, Roll, and Yaw

Imagine an airplane with a stick pushed through it from nose to tail, so the plane can spin on the stick. This type of rota­tion is called roll, and the stick is the roll axis. A stick pushed through a plane from wingtip to wingtip is the pitch axis. A stick pushed through a plane from top to bottom is the yaw axis. The position, or angle, of an aircraft-the amount of pitch, roll, and yaw it has-is called its attitude. In a standard airplane, the pilot generally can change the plane’s atti­tude by operating controls that move the elevators, ailerons, and rudder.

Changing an airplane’s pitch makes its nose tip up or down. The pilot changes the pitch by using the control stick to tilt the elevators, which are at the back of the tail. Pulling the stick back tilts the elevators up. Air flowing over them pushes the plane’s tail down and raises its nose. Pushing the stick for­ward has the opposite effect.

Rolling, or banking an aircraft to one side, enables it to turn. When it rolls, the lift produced by the wings tilts to one side instead of acting straight upward. The sideways part of the lift pulls the plane into a turn. A pilot makes a plane roll by pushing the control stick to one side or (on a larger airplane) turning the yoke on top of the control column. This control moves the ailerons, which are at the back of the wings. When the

О The B-2 Spirit Bomber (along with other flying wing aircraft) has elevons (circled) at the back of its wings that function as combined ailerons and elevators.

aileron on one wing tilts down, the wing rises. The aileron on the other wing tilts up, and the wing sinks.

Yaw is the name for the motion when a plane’s nose turns to the left or right.

Yaw is controlled by a rud­der, which is mounted on an airplane’s tailfin. The rudder is operated by a pair of foot pedals. Turning the rudder to one side pushes the plane’s tail to the opposite side and swings the nose around. When a plane rolls into a turn, the pilot also adjusts its pitch and yaw to keep the plane’s nose pointing in the right direction.

n the early 1900s Albert Einstein (1879-1955) produced two theories that caused a revolution in science. Together, they are known as the theory of relativity.

The first of Einstein’s relativity theo­ries is his Special Theory of Relativity of 1905. This states that:

(1) The laws of physics are the same for people moving at different speeds.

(2) The speed of light is always the same for all observers, no matter how fast they are moving.

These two simple principles produce some surprising effects when speeds close to the speed of light are involved.

There is no such thing as absolute rest anywhere in the universe. Someone standing still on Earth is actually moving because Earth is spinning. The planet also is orbiting the Sun. The Sun orbits the center of the Milky Way (our

galaxy), and the Milky Way moves through space among billions of other galaxies that also are moving. Any observer can say that he or she is at rest and everything else in the universe is moving in relation to—or relative to— him or her. This phenomenon gives relativity its name.

One of the most surprising effects of relativity is that times and lengths depend on who measures them. Imagine that one person stays on Earth while her twin goes on a long spaceflight almost as fast as the speed of light. The person on Earth would see the spacecraft become shorter as it accelerates toward the speed of light. This is called Lorentz contraction. Also, time runs more slow­ly as speed increases. When the astro­naut twin returns to Earth, she would be younger than her earthbound twin. This is known as the “twins paradox.”

The Special Theory of Relativity also predicts that as something goes faster, it becomes more and more difficult to make it go even faster. The more energy it has, the more inertia it has. Einstein also showed that energy

О The twins paradox illustrates Einstein’s theory that if two bodies at the same point accelerate to different speeds and then meet again, they will find that a different amount of time has elapsed for each of them.

and mass are linked. He produced his famous equation, E=mc2, to show how they are related. In this equation, “c” is the speed of light, a huge number, so even a tiny mass (m) is equivalent to an enormous amount of energy (E).

In 1915, Einstein produced a new theory, his General Theory of Relativity, which added the effect of gravity to the Special Theory. Nobody had been able to explain how gravity works. Einstein imagined that space is flat and all objects dent it, like heavy weights sitting on a stretchy sheet. In other words, mass bends space. The paths of moving objects curve toward massive objects, simply because space itself is curved there. Light also is bent by curved space.

Global Positioning System (GPS) navigation satellites fly around the world at 7,000 miles per hour (11,300 kilometers per hour). According to special relativity, their onboard clocks should run more slowly than clocks run on Earth. According to general relativity, the curving of space caused by Earth has the opposite effect. It makes the clocks run faster than clocks on Earth. The result of these two coun­teracting effects is that the satellite clocks run 38-millionths of a second faster every day than clocks on Earth. It is a tiny error, but GPS clocks have to be more than 1,000 times more accurate than this. So satellite clocks are deliberately set to run slow before they are launched, so that they are correct in orbit.

Relativity is not just a strange set of ideas and mathematics. Its effects are real. Observations and experiments have confirmed many of its predictions. Spacecraft designers and planners of space missions have to allow for them.

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SEE ALSO:

• Einstein, Albert • Global Positioning System • Spaceflight

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Date of birth: November 18, 1923.

Place of birth: East Derry, New Hampshire. Died: July 21, 1998.

Major contribution: First American in space.

Awards: Congressional Space Medal of Honor; two NASA Distinguished Service Medals; NASA Exceptional Service Medal; Navy Distinguished Service Medal; Navy Distinguished Flying Cross; several other trophies, medals, and honorary degrees.

fter Alan Shepard’s first trip in an airplane, in his early teens, he became fascinated by flying. He often visited the local airport, doing odd jobs in the hope of a plane ride. Shepard attended the U. S. Naval Academy at Annapolis, Maryland. Graduating in 1944, he served on a destroyer during the last year of World War II. After the war, Shepard became a navy pilot, and, in 1950, he became a test pilot.

In 1959, the National Aeronautics and Space Administration (NASA) began recruiting the first American astronauts. The agency sent invitations to the top 110 test pilots. Shepard entered the pro­gram and soon after was named as one of the seven Project Mercury astronauts. After two years of training, Shepard was chosen to be the first American in space.

Weather and technical problems delayed Shepard’s flight, but the launch finally took place on May 5, 1961. Takeoff was smooth, and the flight was brief. Shepard never reached orbit—he simply went up and, about 15 minutes later, splashed down. Splashdown and recovery were successful. The launch and the recovery were covered live by television, and Americans greeted Shepard as a hero.

After the celebrations were over, Shepard returned to NASA. In 1964, before he could make another space­flight, he developed a serious problem in his inner ear. Fluid buildup would, from time to time, cause him to lose his balance and feel nauseous. NASA ground­ed Shepard, and he took on the alternative job of chief of astronaut opera­tions. After several years, he decided to have sur­gery to try to correct his ear problem. The 1969

О Alan Shepard is seen here being recovered by a helicopter after splashdown in May 1961.

О Alan Shepard was photographed on the Moon with a transporter used for carrying equipment and samples. Shepard and fellow astronaut Edgar Mitchell spent more time on the Moon (33 hours) than any other Apollo astronauts.

operation was a success, and soon after, Shepard was cleared for spaceflight again.

Shepard was ready to achieve his dream of flying to the Moon. He was named commander of Apollo 14, teamed with Edgar Mitchell and Stuart Roosa. On January 31, 1971, Shepard returned to space. Five days later, he and Mitchell landed on the Moon. They spent more than a day on the Moon’s surface, where they collected a large sample of moon rocks and carried out several experi­ments. Having completed their mission, the astronauts returned safely to Earth.

Shepard continued as chief of astro­naut operations until he retired from NASA three years later. He began work­ing in business, where he was successful in several ventures. In 1984, Shepard, five other Mercury astronauts, and the widow of a seventh astronaut formed a foundation that gave scholarship money to students interested in science and engineering. Shepard led the foundation until stepping down in 1997. He died the following year.

GOLF ON THE MOON

On Apollo 14, Shepard decided to indulge his passion for golf. Before the flight, he had a NASA worker cut the head off a golf club and attach a device that could be used to connect it to a Moon exploration tool. Before launch, Shepard stuffed the club head and two golf balls into a sock and hid them in his spacesuit. At the end of his Moon walk, he surprised NASA officials by attaching the club head and smacking the two balls. All this took place on live television. Although the first ball did not go far, the second-Shepard announced – traveled for "miles and miles."

he aerospace industry makes and services aircraft, spacecraft, and associated equipment. Aerospace manufacturers make airliners, airfreight carriers, warplanes, helicopters, and general aviation airplanes. They also build guided missiles, engines, and other equipment, including electronics and air traffic control systems. The industry’s space activities include making commercial telecommunications satel­lites, navigation satellites, and science satellites. Aerospace companies build and adapt launch vehicles, such as multistage rockets, the Space Shuttle, and the ground systems that control spaceflights. The industry also takes care of the overhaul, rebuilding, and conver­sion of air and space vehicles.

Industry Overview

The United States has the world’s biggest aerospace manufacturing sector. Its biggest customer is the federal govern­ment. Military airplanes, missiles, and other equipment are ordered by the U. S. Department of Defense. The main purchaser of space vehicles (satellites and launch vehicles) is the National Aeronautics and Space Administration (NASA), also a federal agency.

Passenger and cargo-carrying air­craft form the biggest sector of the civil part of the industry. These planes are supplied to air transportation busi­nesses, such as airlines and airfreight businesses. Smaller businesses buy air­craft of many kinds. Satellites are sold to television companies and other commu­nications businesses. The aerospace manufacturing industry also supplies airports and space centers with all kinds of service equipment—everything, in fact, that keeps airplanes and space­craft flying.

Every large aerospace corporation works with a network of smaller compa­nies. These businesses supply all types of components, from weapons and avionics to airliner seats and carpets. On major projects, corporations often cooperate with partners to cut costs and share expertise. For example, the European Aeronautic Defence and Space Company (EADS), which makes the Airbus airliner, was originally a consortium of British, French, Spanish, and German companies.

U. S. aerospace companies are pri­vately owned. In some other nations, however, the government controls the aerospace industry. Before the breakup of the Soviet Union in the 1990s, all Soviet military and civil aircraft were built by the state-controlled aerospace sector. There are other examples of national aerospace firms, such as Saab of Sweden. Government industries, such as those in Israel and China, usually build airplanes for their armed forces.

he term air traffic refers to all air­craft in the air, about to fly, or just landed. Air traffic control is per­formed by people on the ground whose job is to ensure air safety at all times. Safety is a matter of concern for all fliers, whether they are piloting private airplanes, military jets, or airliners. Pilots have the final responsibility for the safety of any aircraft, but they must also follow instructions given by con­trollers on the ground.

Air traffic controllers make sure that aircraft of all sizes move safely around in the sky. Their work is of special importance around airports, where the sky is often crowded with airplanes. Air traffic control makes sure that planes taking off and landing do so in a safe, orderly, and efficient manner.

From the 1940s to the 1960s, U. S. engi­neers built a series of research airplanes to explore supersonic flight. These craft included the Bell X-1, Bell X-2, Douglas Skyrocket, and X-15—all were record breakers. Their flights helped engineers design supersonic jet fighters and manned spacecraft. The British Fairey Delta 2 (FD-2) set a world airspeed record of over 1,000 miles per hour (1,609 kilometers per hour) in 1956. The small FD-2 had the same delta wings

SECRET EXPERIMENTATION

Research flying is often secret. Developed in secret between 1975 and 1982 by Lockheed for the U. S. Defense Advanced Research Agency, the F-117 Nighthawk was in U. S. Air Force service years before it was revealed to the public.

Phantom Works, a project division of McDonnell Douglas (now part of Boeing), tested a different aircraft, the Bird of Prey, from 1996 to 1999. Termed an "invisible airplane," the Bird of Prey was hard to detect because of its shape, the way it was painted, and stealth specifications similar to those of the F-117.

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and drooping nose made familiar by Concorde in the 1980s.

Not all experimental airplanes fly higher or faster. The Altus is a civilian version of the military Predator, a U. S. drone used after 2000 in wars in Afghanistan and Iraq. Altus carries scientific instruments to sample the atmosphere, flying at only 80 miles per hour (129 kilometers per hour), but it is able to stay in the air for up to 24 hours. The Proteus airplane can also stay in the air for up to a day. It is designed by Burt

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Rutan, innovative designer of Voyager, an airplane that flew nonstop around the world (in 9 days) in 1986. Rutan also produced SpaceShipOne, the world’s first successful private spacecraft.

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SEE ALSO:

• Bell X-1 • Concorde • Engine

• Glider • Jet and Jet Power • Kitty Hawk Flyer • Rocket • Wright,

Orville and Wilbur

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Airports have fuel stores and hangars, which are like giant garages for air­planes. Hangars are also workshops in which aircraft can be serviced or repaired between flights. Other areas of the airport include the aircraft parking area, or loading apron. Here, a plane is refueled, and airport workers load cargo, baggage, and supplies.

Airports that handle passengers have passenger terminals of various sizes. Airports lease space to airlines for offices, ticket counters, and baggage areas. They also rent space to restau­rants, stores, car rental agencies, and other businesses within the airport.

The airport management may also run parking lots. Most big airports have
huge parking zones around the airport for short-stay and long-stay parking and for car rentals.

Large airports have separate cargo terminals for incoming and outgoing cargo. Airfreight often needs quick, careful handling, because it may include delicate equipment or foods and flowers that spoil quickly. Many airliners use big cargo planes with wide-opening doors into which containers and packages are loaded from forklift trucks and elevated loading bays. Security is strict, because airfreight often includes such high-value items as bank bonds or gold.

Aircraft use an instrument called an altimeter to measure altitude. Airplanes have two different types of altimeters. The pressure altimeter measures a plane’s altitude above mean sea level. As an airplane climbs higher in the atmos­phere, the air pressure falls. Measuring the air pressure shows how high the plane is. A pressure altimeter, or baro­metric altimeter, is accurate to within about 20 feet (6 meters).

MEASURING ALTITUDE WITH SATELLITES

Airliners fitted with satellite naviga­tion can use it to measure altitude. Radio signals received from naviga­tion satellites are used to measure the distance between the plane and the satellites. (The positions of the satellites used are precisely known.) Signals received from three satellites enable a plane to determine its posi­tion on a map. Adding a signal from a fourth satellite also enables the plane to figure out its altitude.

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As an airplane descends for landing, however, it is more important to know its height above the ground than its pressure altitude. The radio altimeter is switched on when a plane descends below 2,500 feet (762 meters). The altimeter aims radio waves at the ground and measures the time it takes for them to reach the ground and travel back up to the airplane. It uses the measurement to calculate the distance between the plane and the ground. The radio alti­meter can measure a plane’s height above the ground to within about 2 feet (0.61 meters).

SEE ALSO:

• Air and Atmosphere • Pressure

vionics is the name for an air­craft’s electronic equipment and electrical systems. Avionics have become so important in modern aviation that they can account for more than half the multimillion-dollar price of a modern aircraft.

Avionics Development

Until the 1940s, the most complicated electronic equipment carried by any air-

О Sensors constantly monitor for problems and are crucial to safety in spaceflight. These NASA astronauts and technicians are examining a sensor system installed on the Space Shuttle Discovery in 2005. The system, a long boom with camera and lasers on the end, is used to inspect the Space Shuttle’s heat shield for damage while in space.

craft was probably a radio. Then radar was developed to detect aircraft a long distance away. Radar soon became small enough and light enough to be carried by aircraft. The amount of electronic equipment in aircraft increased rapidly. The word avionics has been used to describe an aircraft’s electronic systems since the 1970s.

At first, an aircraft’s avionics were a collection of separate electrical and electronic circuits, each with its own wiring. Today, all the various circuits and systems work together, connected to an information highway called a data – bus. The databus carries information around an aircraft’s avionics systems in the same way that a computer’s databus carries information between the key­board, processor, memory, monitor, and other parts.

A lot of work goes into making sure that the different pieces of avionics equipment will work together in an aircraft without inter­fering with each other. This process is called systems integration. A big project, such as a new airliner, often has hundreds of engineers working on systems integration.