Category FLIGHT and M ОТІOIM

biplane is an airplane with two sets of wings, one above the other. The biplane was developed from the box kite, which was invented by an Australian named Lawrence Hargrave in 1893.

Before the days of powered flight, aviation pioneers, such as Otto Lilienthal in Germany and Octave Chanute in the United States, flew biplane hang gliders. They experimented with how to control an aircraft carrying a human pilot with no engine. The first controlled powered flight, in 1903, was made by a biplane, the Wright brothers’ Flyer. The first powered flight in Europe was also made by a biplane, this time flown by a Brazilian pilot called Alberto Santos – Dumont, in 1906.

One Wing or Two?

In the early years of airplane develop­ment, engineers were not sure which design flew best: the monoplane (with one wing) or the biplane (with two wings). They tried adding more wings to see if this worked. In 1908 the first tri­plane (with three wings) took to the air, but triplanes never became widespread.

The biplane appeared to fly more steadily than the monoplane. Engineers believed this was because two wings gave more lift than one wing. In fact, a disadvantage of the biplane is that the two sets of wings tend to interfere with one another, thereby reducing lift and increasing drag.

Overall, early wing designs were not very efficient. There was little difference between the performance of monoplanes and biplanes in the days of low-power engines and slow speeds. Biplanes were stronger than monoplanes, however— their wings were braced by taut wires and wooden struts. This was important in the early days, before 1930, when most airplanes were flimsy structures of wood and cloth. The wings were an air­plane’s weakest point, and it was not unusual for the wings to fall off when a plane was diving or turning, usually with fatal consequences for the pilot.

To improve lift and reduce drag, biplane designers tried “staggering” the wings. This usually meant fixing the upper wing slightly in front of the lower wing, but there were also biplanes that had the lower wing set farther forward. Staggering worked quite well, and biplanes proved as useful as monoplanes for some time.

William Boeing, founder of the aero­space giant that bears his name, was
born in 1881 in Detroit, Michigan. His father was a wealthy mining engineer of German origin. After graduating in engineering from Yale University, William Boeing made his own fortune trading forestlands in Washington State. Airplanes, however, were his main inter­est. In 1910 he went to Los Angeles to watch planes gather at the first air meet to be held in the United States, but to his disappointment failed to persuade any of the pilots there to take him for a flight.

Boeing found a partner in a U. S. Navy engineer named George C. Westervelt. The two young men were convinced that they could build air­planes, and they began work on a biplane. Having taken to the air for the

first time as a passenger in a Curtiss biplane, William Boeing learned to fly in 1915, taking lessons from pioneer pilot Glenn L. Martin.

The first Boeing airplane was the Model 1, also known as the B&W. It was

a biplane with floats for landing on water, and it flew for the first time on June 29, 1916. Its top speed was only 75 miles per hour (121 kilometers per hour).

Westervelt went his own way, and Boeing set up a business, Pacific Aero Products, to build the B&W. In April 1917, Pacific Aero Products became the Boeing Airplane Company, based in Seattle, Washington. Boeing sold air­planes to the government—the United States was now engaged in World War I.

Back in 1981, Columbia had been the first Space Shuttle to go into space. The tragic accident on February 1, 2003, that destroyed the spacecraft and claimed the lives of its crew took place at the end of its twenty-eighth mission.

While Columbia was still in space, engineers studied video images of its launch. The images showed a piece of insulating foam falling off the external fuel tank and hitting Columbia’s left wing 82 seconds after liftoff. It was not a serious concern at the time. When Columbia began its return to Earth from space, however, it began to heat up. As Columbia hurtled deeper into the atmos­phere, ground controllers noticed that sensors in the left wing were showing unusually high temperatures. Then, the
sensors failed. Sensors in the landing gear inside the left wing showed tire pressures rising, and then these sensors failed, too. A few seconds later, radio contact with the crew was lost.

Although Columbia was still nearly 39 miles (62.8 kilometers) above the ground, traveling at more than 12,500 miles per hour (more than 20,000 kilo­meters per hour), eyewitnesses on the ground could see it was breaking up. They saw flashes and streaks of light

О The last crew of the Space Shuttle Columbia were (from left to right): Mission Specialist David Brown, Commander Rick Husband, Mission Specialist Laurel Clark, Mission Specialist Kalpana Chawla, Mission Specialist Michael Anderson,

Pilot William McCool, and Payload Specialist Ilan Ramon.

coming from its bright trail in the sky and knew this was not what a reentering Space Shuttle usually looked like.

Debris fell over a huge area. Pieces of wreckage were collected from 2,000 locations across the United States.

Investigation

A team of independent experts investi­gated the cause of the accident. They carried out experiments to see if a piece of foam falling from the external tank could have damaged the spacecraft’s wing. It seemed unlikely because the leading edge of the wing is much harder and stronger than the foam. The wing was made of a material called reinforced carbon-carbon. Surprisingly, experi­ments showed that a piece of foam could indeed punch a hole straight through the wing’s leading edge.

If the foam that fell off the fuel tank just after Columbia’s launch made a hole in the left wing, hot gas would blast through the hole to inside the wing during reentry. It would burn and melt its way through the wing’s internal structure. This explains why sensors in the left wing showed rising temperatures and then failed. The weakened wing would have broken up, quickly followed by the rest of the vehicle.

All Space Shuttles were grounded for more than 2 years while the problems were investigated and resolved. Space Shuttles are now inspected in space dur­ing each mission to check for damage that might prove dangerous during the spacecraft’s return to Earth.

Challenger’s wreckage was buried in an unused missile silo at Cape Canaveral. Columbia’s wreckage is stored in the Vehicle Assembly Building at the Kennedy Space Center. Parts of it are used for research. When Columbia broke up, pieces of all shapes, sizes, and mate­rials flew through the atmosphere at speeds they were not designed for. Scientists and engineers are interested in precisely what happened to them, what temperatures they experienced, and how they were affected. The lessons learned by studying these pieces may help in the design of future high-speed aircraft.

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Date of birth: April 15, 1452.

Place of birth: Anchiano, Italy.

Died: May 2, 1519.

Major contributions: Artist; engineer; developer of early designs for parachutes and helicopters.

eonardo da Vinci was born during the Italian Renaissance, a period marked by great interest in the arts and literature as well as the begin­nings of modern science. The ideal man of learning at the time was one who could understand many different fields. Leonardo (today, he is often referred to by his first name alone) embodied that ideal.

Paintings such as the Last Supper and the Mona Lisa cemented Leonardo’s reputation as a brilliant artist with a subtle understanding of human emotion. His studies of human anatomy reveal a painstaking attention to detail and knowledge far in advance of his time. The mechanical devices that Leonardo built and sketched prove that he was an accomplished engineer with a powerful imagination. Some of these devices show a brilliant mind wrestling with the the principles and problems of flight.

Leonardo received standard school­ing for his time. When he displayed obvious artistic talent, he was appren­ticed to an artist’s workshop in Florence, Italy, to learn art. From age fifteen to his late twenties, he studied art, drawing, and engineering. In 1481, Leonardo

began to work on his own. Soon after, he began filling notebooks with his observations of the world and his thoughts about them.

Leonardo lived much of his adult life away from Florence, working for the duke of Milan and the king of France. He was renowned for his skill as a painter, sculptor, and designer of machines, including weapons.

Early in his life, Leonardo had devel­oped an interest in designing a machine that could fly. To prepare for this possi­bility, he carefully studied the properties of air and the anatomy and flight of birds. These studies led Leonardo to propose several remarkable ideas. In 1500, for example, he suggested that the weight of a person could be carried by a tentlike structure made of cloth. Leonardo sketched such a cloth para­chute in the shape of a pyramid. Near the drawing, he predicted that by using it a person could “throw himself down from any great height without sustain­ing any injury.” Modern adventurers have built such a device, following Leonardo’s design, and have managed to use it successfully.

That same year, Leonardo sketched an even more remarkable device: a heli­copter with a central screw that could turn the propeller. His notes explained how springs could be used to turn the screw, but here Leonardo ran up against the limitations of technology: at the time there was no mechanical force pow­erful enough to provide the needed lift.

Leonardo spent much time trying to figure out how to create an ornithopter, a device that achieved flight by having a person flap its wings. The action was not always carried out with arms-in some versions, Leonardo intended the power to be provided by the flier’s legs. Unfortunately, humans do not have enough muscle to lift their weight into the air in this way. Also, Leonardo did not quite understand how bird’s wings provide both thrust and lift. His designs were doomed to failure. According to legend, he tested one of his designs using a servant-the story says that the servant crashed and broke his leg. Leonardo’s last drawing of a flying

machine abandoned the ornithopter for a fixed-wing glider. He described how the pilot could shift weight in the craft to change its direction.

Leonardo’s notebooks hold about 150 drawings of flying machines. His vision­ary ideas did not influence the history of aviation, however. His notebooks were forgotten until the 1800s, and by that time some early advances in flight had already been made.

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• Glider • Helicopter • Lift and

Drag • Ornithopter • Parachute

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n ejection seat is a complex piece of equipment with a sim­ple aim: to save pilots’ lives by propelling them out of airplanes that are damaged and unable to land safely. Ejection seats are used in warfare-they are not found on civilian aircraft. They have saved hundreds of pilots’ lives.

How It Works

Aircraft crew members sit in ejection seats during normal flight. The seat has
the basic parts of bucket, back, and headrest as well as some special features. Ejecting at supersonic speed subjects the human body to forces in excess of 20g (twenty times the force of normal gravi­ty). The seat, therefore, is designed to protect the body from g-force and from debris. Once clear of the airplane, a parachute opens.

A combat pilot may have to eject because of engine failure or a collision with another aircraft, or after being hit by missile attack. The process has to be quick. To activate the ejection seat, the pilot can do one of two things: pull a handle attached to the seat or pull down a small curtain that will protect the pilot’s face. The pilot’s action begins a sequence that removes the canopy from the cockpit and sends the seat (which is mounted on rails) shooting up and away from the airplane. It is catapulted clear by a ballistic cartridge working with a rocket unit fitted underneath the seat. Once clear of the air-

О In 2003, Captain Christopher Stricklin ejected from a Thunderbird aircraft less than a second before it hit the ground at an air show in Idaho. The pilot had miscalculated a maneu­ver and knew he could not save the aircraft. He ejected after guiding the jet away from the crowd of more than 60,000 people and was not himself injured.

plane, a small drogue parachute opens to slow the seat before the main descent parachute deploys. The pilot can discard the seat before landing.

The modern fighter pilot has a comput­erized control system. Not only does it fly the airplane, but it also detects a target and fires missiles long before the pilot can even see the target. A display panel shows the pilot a virtual picture of the combat zone as the airplane “locks on” its guided weapons-all this while flying at twice the speed of sound.

With so much equipment and weaponry to carry, fighter aircraft have

become steadily larger. The F-4 Phantom used in the Vietnam War weighed four times as much as a World War II Mustang, and a modern F-15 is almost ten times heavier. There are a few excep­tions, such as the lighter AV8 Harrier Jump Jet and the F-117 Nighthawk.

Modern fighters include the F-14 Tomcat, a shipboard interceptor, with variable-geometry wings, or swing wings. The aircraft flies well at low speed, with its wings extended, but also has good performance at supersonic speed with its wings swept back. One of the most successful U. S. fighters is the F-16 Fighting Falcon. Sold to a number of countries, this agile, single-seat air­craft is capable of flying at 1,320 miles per hour (2,124 kilometers per hour).

Current frontline fighters, such as the F-15 Eagle, fly at Mach 2.5 and climb to

100,0 feet (30,480 meters). They are armed with cannons and air-to-air missiles and can carry an additional

16,0 pounds (7,264 kilograms) of weapons externally. Like many modern airplanes, the F-15 has had a long life. Design studies began in the late 1960s, the first prototype flew in 1972, and the aircraft saw its first combat in the Gulf War of 1990. The F-15’s replacement is the multi-role F-35 Lightning II Joint Strike Fighter, which made its inaugural flight in 2006.

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• Aircraft, Military • Bomber

• Control System • Radar • World

War I • World War II

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Personal flying (by balloon, glider, hang glider, microlight, paraglider, and mini­copter) will continue to boom. Flying is one of the world’s fastest-growing sports. Electric air vehicles hovering in city airspace would help reduce the traf­fic on overcrowded highways. Flying cars are already being developed.

The world’s first piloted fuel cell – powered airplane is a two-passenger electric aircraft. Based on the French – built DynAero Lafayette airframe, its hydrogen fuel cells are backed up by batteries like those in electric cars. Solar-powered microlight aircraft also might fill the skies over future cities. It is possible that solar-powered airplanes will replace oil-burning airplanes as the world begins to run out of oil.

The Global Positioning System, or GPS, is a network of satellites that enables anyone on Earth’s surface, or flying above it, to find out exactly where they are. The system belongs to the United States, but it is not the only satellite positioning system. Russia has developed a similar system, called the Global Navigation Satellite System

О The first satellite positioning systems were set up by the United States and the Soviet Union to give their submarines a way of figuring out exactly where they were during long patrols of the vast oceans. In 1989, this sailor on the USS Alabama checks information provided by GPS to pinpoint the submarine’s location.

(GLONASS). A group of nations in Europe and elsewhere in the world is developing a satellite positioning system named Galileo.

The Idea

When the first satellites were launched into space in the late 1950s, scientists were able to locate them and follow their movements through radio signals the satellites sent back to Earth. They soon realized that this might work in reverse. A satellite’s radio signal could be used to figure out the location on Earth of the radio that received it.

Three satellites would enable a radio receiver to calculate its position on the ground. A fourth satellite would enable the receiver’s altitude to be calculated as well. In order to have four satellites in view above the horizon all the time,

there would have to be at least twenty – four satellites orbiting the planet. A pro­gram based on this idea, the Global Positioning System (GPS), was devel­oped by the U. S. Department of Defense.

First, scientists had to prove that such a system would really work. Two experimental satellites, Timation 1 and Timation 2, were launched in 1967 and 1969. In 1974, a third experimental satellite, Navigation Technology Satellite 1 (NTS-1), was the first satellite to carry an atomic clock. Finally, NTS-2 was launched in 1977 to test all the systems and software before the first GPS satel­lite was launched in 1978. The whole network of twenty-four satellites was completed in 1994.

Ever since the first reliable helicopters took to the air, these rotary-wing air­craft have been widely used all over the world for both military and commercial purposes. Helicopters are not cheap to operate, and they are noisy, but their flexibility has made them extremely useful that it is hard to imagine a world without them.

A disadvantage of a helicopter is that it is slower than a fixed-wing aircraft. Most helicopters travel at speeds of less than 200 miles per hour (320 kilometers
per hour). One way to make a helicopter go faster is to add jet-thrust engines or propellers for forward flight. This pro­duces a compound helicopter that can fly at more than 340 miles per hour (550 kilometers per hour).

The first helicopters had piston engines, but most modern helicopters are powered by a gas turbine jet engine called a turboshaft. Some helicopters, especially military craft, have short stubby wings that provide extra lift dur­ing forward flight. The wings also are used for attaching payloads and as mounts for missiles and other weapons.

The Soviet Union has built some of the world’s biggest helicopters, such as the Mil Mi-26, probably the heaviest helicopter ever flown. A rival U. S. heli­copter, the Sikorsky CH-53E Super Stallion (1974), used just one extra-large rotor with a diameter of 79 feet (24.08 meters). It could carry a crew of three and up to fifty-five troops.

While setting these aviation records, Hughes was building a powerful aircraft company, Hughes Aircraft, founded in 1932. When World War II broke out, Hughes hoped to produce aircraft for the U. S. war effort. Other manufacturers won the contracts for this work, howev­er, and Hughes only received a contract for two experimental planes.

The experimental aircraft Hughes produced were both innovative, but they were unsuccessful. The first crashed while Hughes was flying it. The second

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ACCIDENT AND INJURIES

Hughes’s first experimental plane, the XF-11, nearly killed him. It was meant to be a high-altitude spy plane that could be used to take photographs without being seen by enemy radar. Before it was finished, World War II ended. Hughes contin­ued working on the plane, however.

On July 7, 1946, he took it on a test flight that developed problems. The plane crashed, destroying three homes in Beverly Hills, California, in the process. The crash and resulting fire left Hughes with many injuries and severe burns. He began taking powerful painkillers while recovering from these injuries—drugs that led to an addiction that plagued him for the rest of his life.

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experimental aircraft was a flying boat so large that it could carry more than 700 passengers. The U. S. military hoped to use the giant aircraft to carry troops across the Atlantic Ocean without wor­rying about attacks by German sub­marines. Unable to get aluminum need­ed to build the plane, Hughes built it of wood. That produced the plane’s nick­name, the Spruce Goose (although it was actually made of birch, not spruce). Its official name was the Hughes H-4 Hercules. The Spruce Goose had a wingspan of 320 feet (98 meters), longer than a football field. The plane was flown only once, on November 2, 1947. That day, Hughes piloted it a distance of 1 mile (1.6 kilometers) in the harbor of Long Beach, California. The plane did not rise above 80 feet (25 meters). It remained in the harbor at the cost of a million dollars a year until Hughes’s death. The Spruce Goose is now dis­played in the Evergreen Aviation Museum in McMinnville, Oregon.