Category FLIGHT and M ОТІOIM

Date of birth: July 24, 1897.

Place of birth: Atchison, Kansas.

Died: July 2, 1937.

Major contributions: First woman to fly alone across the Atlantic Ocean; first woman to fly alone across the United States; first person to fly from Hawaii to California.

Awards: Distinguished Flying Cross; French Legion d’Honneur; Harmon International Trophy; National Geographic Society Medal.

ne of the most celebrated of women aviators, Amelia Earhart is also at the center of a great mystery. On her last flight—a daring attempt to fly around the world—she disappeared, leaving no trace of herself or of her aircraft.

Early Life

In 1917, the year after she graduated from high school, Earhart joined the Canadian Red Cross to help soldiers fighting in World War I. Working at a military hospital, she got to know some airmen and became interested in flying. Earhart flew in an airplane for the first time in 1920, when she immediately became captivated by flying. She began taking flying lessons, although her parents objected. After earning her pilot’s license, Earhart scraped together enough money to buy an airplane.

Within weeks, Earhart set a record for women by reaching an altitude of

14,0 feet (4,270 meters). The record did not stand long, but the flight showed her daring. By the mid-1920s, Earhart’s parents were divorced, and she was living in Massachusetts with her mother. Earhart took a job as a social worker in Boston and on weekends she flew.

A fighter airplane is an aircraft designed for combat, usually with other military aircraft. Fighters are fast, agile, and equipped with detection systems and weapons to hunt enemy aircraft and shoot them down. A modern fighter plane flies up to 2.5 times the speed of sound (Mach 2.5). Because of the amount of weaponry it carries, a fighter is often as heavy as a World War II bomber.

When fuel burns, it combines with oxygen in the air. Without oxygen, fuel will not burn. Rockets have to function in space, where there is no air to supply oxygen, and so they carry their own supply of oxygen-or a chemical that contains oxygen, called the oxidizer – for burning the fuel. The fuel and the oxidizer also are called propellants.

Rockets can use kerosene fuel, just as aircraft do. The rocket fuel RP-1 is kerosene. The first stage of the giant Saturn V rocket that launched astro­nauts to the Moon during Project Apollo burned RP-1.

Hydrogen is another popular rocket fuel. The Space Shuttle’s main engines burn hydrogen and oxygen from an external tank. Hydrogen and oxygen are normally gases, but the tanks needed to carry enough of these gases to launch a heavy rocket into space would be gigantic. Hydrogen and oxygen, there­fore, are cooled and compressed until

TYPES OF FUEL

Every fuel has a flash point. The flash point is the lowest temperature at which a fuel can be set on fire by a spark or flame. A fuel with a low flash point catches fire more easily than a fuel with a high flash point. Avgas has a lower flash point than jet fuel.

they change to liquids, which take up much less space. Hydrogen has to be cooled to -423°F (-253°C). Oxygen has to be cooled to -298°F (-183°C). Super­cold propellants such as these are known as cryogenic propellants.

There are some chemicals that burst into flames as soon as they meet. They are useful as rocket propellants because they do not need a spark or flame to start them burning. Propellants of this type are called hypergolic propellants. Turning off the supply of hypergolic propellants stops a rocket from working. Turning them on makes the rocket fire again. Hypergolic propellants are used by small rockets that have to start and stop frequently, such as those that help the Space Shuttle maneuver in space.

O A solid rocket booster is maneuvered into place on a Delta II rocket that is being prepared for launch by NASA at Cape Canaveral Air Force Station in Florida.

The simplest rockets burn solid fuel, like giant fireworks. The fuel and oxidizer are mixed while liquid and then poured into the rocket, where they set hard. To fire a solid fuel rocket, a flame is sent down a hole through the middle of the rocket. Once a solid fuel rocket starts firing, it keeps going until all the propellant is used up. Small solid rockets are often strapped to the side of a bigger rocket to supply extra thrust for takeoff. The biggest solid fuel rockets ever built are the two solid rocket boost­ers (SRBs) that help to launch the Space Shuttle.

Glenn made history one more time. After he announced his retirement from politics, Glenn was asked by NASA if he would like to go into space one more time, on a Space Shuttle mission. The gesture was made partly to honor him and partly to study the effects of space­flight on older people—Glenn was in his seventies at the time. Glenn jumped at the chance to join the mission.

On October 29, 1998, Glenn left Earth once again. It was almost thirty-seven years since his first flight. Things had changed. This time, he was on board the Space Shuttle Discovery and had six crewmates instead of being the lone astronaut. The flight took more than nine days, whereas his previous flight

INSPIRATION FOR THE FUTURE

"The most important thing we can do is inspire young minds and to advance the kind of science, math, and technology education that will help youngsters take us to the next phase of space travel."

John Glenn, speaking as spokesperson for National Space Day, 2000

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had lasted just over 4 hours. For Glenn, going into space again was an enormous thrill.

After the flight, Glenn retired from public life. He and his wife Annie settled back in Ohio. Both served on the board of trustees at Muskingum College, where they had studied so many years before. Glenn opened a center at Ohio State University to encourage young people to start careers in public service.

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SEE ALSO:

• Astronaut • NASA • Pilot

• Spaceflight • Space Race

• Supersonic Flight

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Hang gliders can fly at speeds of up to 90 miles per hour (145 kilometers per hour), and they can encounter some rough weather conditions. They also can be tricky to fly. For these reasons, trainee pilots learn basic hang gliding skills on the ground and during brief “hops” into the air. Pilots in training will often

О A well-positioned platform sticking out from a hill also makes a good launching pad for a hang glider.

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PARAGLIDERS

A paraglider flies in a way similar to a hang glider. The difference is that a paraglider looks more like a parachute and has no rigid frame. The pilot sits in a seat harness

suspended beneath the canopy. The term paraglider was first used by aviation scien­tists in the 1960s. The sport paraglider was developed in the 1970s by French enthusi­asts, who were inspired by new, advanced parachute designs. French pilots made paragliding popular, and France still has the largest number of paragliders.

The paraglider is easy to pack and light enough to be carried, which is useful when a flight ends with the pilot landing miles away from the takeoff area. The paraglider trainee can learn most skills in the air.

The aircraft is easy to launch and fly in light winds, but it does not glide as well as a hang glider. For this reason, it usually cannot fly such long distances, although some paragliders have flown as far as 250 miles (400 kilometers).

fly tandem (two at a time) with an expe­rienced instructor.

The United States Hang Gliding Association provides licenses to hang glider pilots. This official body also issues certificates to instructors and enforces safety regulations that all pilots are expected to observe. Hang gliding is often thought to be a risky sport by peo­ple not involved in it. Although modern materials are both light and strong, a hang glider is a flimsy airplane that is
easily damaged. Accidents can happen, often as a result of unpredictable wind currents or weather changes. Hang glid­er pilots can carry a parachute in their harnesses for emergencies.

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SEE ALSO:

• Air and Atmosphere • Bird

• Glider • Global Positioning System

• Lilienthal, Otto • Wing

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Hubble’s precision optics make the most of its unique location beyond Earth’s atmosphere. The atmosphere, the blanket of gases that makes life possible on our

planet, is a hindrance to astronomy. By orbiting in space, above the gases, Hubble gets a much clearer view of the universe. Hubble also can be aimed very accurately to study a specific target, such as a star billions of miles away.

Right after its launch, engineers dis­covered there was something wrong with the telescope. There was a flaw in the optics of the main (primary) mirror. As a result of the flaw, the images Hubble received were not as clear as sci­entists had hoped. The cause of the problem was that the primary mirror had been ground to the wrong shape, in spite

of the care that had been taken to make it accurate. It was too flat at the edges by a microscopic amount, but this was enough to produce what scientists called “severe spherical aberration.” Light reflecting from the edge of the mirror was focused on a different point than the light reflecting off its center, so the picture was blurred.

A Space Shuttle flight in 1993 solved this problem. Astronauts fitted a com­
plex pack of five pairs of smaller mirrors to correct the aberration in the main mirror. It was like fitting a new lens in a person’s eyeglasses to sharpen his or her eyesight. It worked, and Hubble started to send back to Earth astounding images of the distant universe. In 1994, the space telescope was able to send back sharp images of Jupiter during the plan­et’s collision with a comet named Shoemaker-Levy 9, an event that hap­pens only once every few hundred years.

The views from space are stunning, but astronauts live in cramped accommoda­tion. There are two small crew cabins— each is only big enough for one person. Each cabin contains a sleeping bag and has a large window through which the occupant can enjoy the view of Earth while off duty. In space, there is no up or down and no gravity. The weightless astronauts on the ISS can sleep right way up or upside down as they wish.

Space station crews usually bed down inside the sleeping bag. If all three ISS astronauts are sleeping, the third member of the crew can sleep anywhere, as long as the sleep­ing bag is fastened to the floor or wall

О Cosmonaut Gennady Padalka, commander of ISS Expedition Nine, juggles with fruit in the Zvezda service module.

of the crew compartment. No one wants to float around while they are asleep.

Astronauts onboard the space station get into a routine of an 8-hour sleep period at the end of each mission day. Some astronauts report difficulty in sleeping, either because of excitement during the first days of a mission or due to the space sickness that some people suffer. As a space vehicle moves in Earth orbit, the Sun rises about every 90 min­utes! Glaring sunlight shining through a window can disturb sleepers unless they wear a sleep mask.

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Newton’s third law of motion is often stated as, “To every action there is an equal and opposite reaction.” This means that when one object applies a force (the action) to a second object, the second object pushes back in the oppo­site direction with the same force (the reaction). When a rocket stands on its launch pad, for example, its weight
(the action) pushes down on the launch pad. The launch pad pushes up against the rocket with an equal and opposite force (the reaction).

Action-reaction forces should not be confused with the forces that make objects accelerate. Action-reaction forces are always equal and opposite. Whether or not an object accelerates depends on the forces acting only on that object.

The example of a rocket can be used again to illustrate this law. When a rock­et standing on a launch pad fires its engine, the jet of gas from the engine pushes up against the rocket (action), and the rocket pushes down against the gas with equal force (reaction). These forces are equal and opposite, but whether or not the rocket takes off depends on the forces acting only on the rocket itself.

Momentum is a property of all moving objects. It is equal to the mass of an object multiplied by its velocity. The more mass an object has and the faster it moves, the more momentum it has. A heavy airliner has more momentum than a small fighter plane flying at the same speed because the airliner has more mass. In addition, a plane flying at 1,000 miles per hour (1,600 kilometers per hour) has twice the momentum of the same plane fly­ing at 500 miles per hour (800 kilome­ters per hour).

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Planet’s Orbit

О Kepler’s first law stated that a planet’s orbit follows the shape of an ellipse with the Sun at one focus. Most planets have regular, almost circular orbits, but some comet orbits form very "eccentric" ellipses, as shown here.

The force of gravity pulls the rocket down, and the thrust of its engine push­es it up. If the thrust upward is greater than the force of gravity acting on the rocket, the resultant downward force will make the rocket accelerate upward.

microlight is a very light, pow­ered aircraft used for recreation­al flying. Some microlights look like regular light airplanes, but smaller. Others resemble a kite or flying wing with an engine. There are even micro­light amphibians and floatplanes (or seaplanes) that can land on water.

Certain types of microlight aircraft are known as ultralights. In the United States, an ultralight is defined as a single­seat microlight airplane that weighs less than 235 pounds (107 kilograms) when empty and has a top speed of 63 miles per hour (101 kilometers per hour). An ultralight is permitted to fly only during daylight hours and over unpopulated areas of the country.

Slightly heavier, faster microlight aircraft are known as light-sport air­planes, a category introduced by the

U. S. Federal Aviation Administration (FAA) in 2004. Another term sometimes used to describe microlights is recre­ational aircraft.

Building Microlights

Lightweight sports flying became popu­lar in the 1970s, a time when a growing number of people were interested in fly­ing for fun and at low cost. Hang gliders also became popular around this time. It was a fairly simple task to fit a small engine and propeller to a hang glider frame to make a powered aircraft that was fun to fly and for which no pilot’s license was required.

Most microlights are now made by specialty companies, but many have been constructed by individuals who get pleasure from designing and building airplanes. People who build aircraft at home recapture some of the pioneering excitement of the early days of aviation in the early 1900s, when people built planes powered by motorcycle engines.

Older homemade microlights were built from plywood and spruce, covered with cotton fabric. Today, even amateur aircraft builders are more likely to use aluminum for the frame and dacron for the fabric. Some microlights are made of strong, lightweight composite materials, such as an epoxy resin coating contain­ing glass or carbon fiber molded over a plastic-foam body. There are many dif­ferent designs. Experts have said that it would be very difficult to design a new microlight in a way that has not already been tried.

О Building microlights is a popular pas­time. Some microlights, such as this one, are scaled-down, lightweight replicas of vintage military airplanes.

Dates of birth: Joseph-Michel: August 26, 1740; Jacques-Etienne: January 6, 1745. Places of birth: Joseph-Michel: Blaruc-les-Bains, France; Jacques-Etienne: Annonay, France.

Died: Joseph-Michel: June 26, 1810; Jacques-Etienne: August 2, 1799.

Major contributions: Invented the first successful lighter-than-air balloon; carried out first flight of a manned balloon. Awards: Order of Saint Michel.

he Montgolfier brothers were the sons of a prosperous paper manu­facturer from southern France.

Joseph-Michel was interested in science and had few business skills. Jacques – Etienne was trained to take over the family business.

During the early 1780s, Joseph – Michel noticed that a piece of paper rose in the hot air of a chimney. He started thinking about building a device that could use this effect to rise into the sky. Joseph-Michel built a small box of light­weight wood and covered it with fabric. He placed a wad of paper underneath the container and set the paper on fire. The container rose in the air until it hit the ceiling.

Joseph-Michel showed this discovery to his brother, and they began experi­menting. In December 1782 the Montgolfiers built a larger container and tested it outside. The object rose nearly 70 feet (21 meters) on heated air and stayed aloft for a minute or so. The Montgolfier brothers went on to have more successful experiments. They built two larger globe-shaped containers held down by long ropes. The globes rose when heated, although they did not fly because of the ropes.

The Montgolfiers then prepared a large balloon to show the public their invention. They made a sphere out of tough sackcloth, covered it with four fabric panels held together by buttons, and surrounded the entire structure with netting to keep everything in place. On June 4, 1783, the Montgolfiers brought their invention to a square in their hometown of Annonay and lit a fire underneath the balloon. As a crowd

О On September 19, 1783, the Montgolfier balloon rose over the French royal palace of Versailles, watched by the king and queen and a large crowd of spectators.

watched in amazement, the balloon rose. The brothers estimated that it reached 6,000 feet (1.8 kilometers). Carried by the wind, it traveled about 1.2 miles (2 kilo­meters) before coming back to land.

The Montgolfiers took their discovery to Paris, where Jacques-Etienne demon­strated another balloon for members of the Academy of Sciences in mid – September 1783. King Louis XVI and Queen Marie Antoinette asked to see the invention for themselves. Accordingly, on September 19, 1783, Jacques-Etienne sent another balloon aloft. This time he attached a basket that carried a sheep, a rooster, and a duck. The balloon rose and floated on air for nearly 10 minutes, landing more than 1 mile (1.6 kilome­ters) away.

The first person to reach the balloon after it landed was a physician, Jean – Frangois Pilatre de Rozier. Excited, he volunteered to go aloft. During the next few weeks, Jacques-Etienne built a bal­loon that measured 75 feet (23 meters) high and 46 feet (14 meters) across. It had a basket with a container that could hold and sustain a fire to keep the bal­loon aloft. The brothers tested it several
times with Jacques-Etienne or de Rozier. on board but with the balloon held down by ropes. Then, on November 1, 1783, de Rozier and a French army major entered the basket and lit the fire. Once the bal­loon was cut loose, it rose into the air. They cruised for 25 minutes, traveling about 5 miles (8 kilometers) over Paris.

The brothers continued experiment­ing. On January 19, 1784, Joseph – Michel went aloft along with de Rozier and five others. Thereafter, the Montgolfiers abandoned balloons and devoted themselves to other work. Joseph-Michel tinkered with some experiments not connected to flying. Jacques-Etienne returned to papermak­ing and invented a method for making vellum, a strong kind of paper.

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SEE ALSO:

• Aerodynamics • Aeronautics

• Balloon

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