Technology

Future of technology that will change of the world...
An automated steel mill produces huge steel bars at the touch of a button. The computer-controlled machines that roll the glowing bars are products of modern technology. Other ma­chines and methods will turn the bars into a variety of industrial and household products.

Cars, like other inventions of technology, have changed our way of life. The convenience of car travel influences where we live and work and how we use our free time.

Assembly line production, an important method of technol­ogy, increases the amount of goods a worker can produce. In­creased productivity provides more goods for more people.

One technology cleans up after another when a filter press squeezes solid particles out of wastewater in a chemical plant.

Recycling recovers raw materials from wastes and so helps conserve resources used by technol­ogy. The iron and steel in this discarded material is being separated for recycling.

Harmful effects of technol­ogy include the scarring of once-fertile land by opencast, or strip, mining, left. Streams fill with mud, the soil be­comes acid, and plant and an­imal life vanish.

Technology has enabled people to produce more goods and services with less labour. Many factories use mass production techniques. This has led to greater productivity, allowing factory workers to enjoy more leisure time.

Work in an Industrial Country

Percentage done by machines, people, and animals:

1840’s: Animal (52%), People (13%), and Machines (35%)

1990’s: Animals (less than 1%), People (1%), and Machines (more than 98%)

(In 1850, machines did only 35 per cent of farm and industrial work in the most developed countries. This chart shows how the 1850 percentages compare with those of 1990, when ma­chines did over 98 per cent of the work).

Technological advances around the home - Technology has brought a host of beneficial products to our homes in the past 150 years. The car enables us to travel much faster than did the horse-drawn carriage of the 1840's. With such inven­tions as the sewing machine and the washing machine, we can perform household tasks more rapidly and with less effort. The air conditioner makes our homes more com­fortable, and electric devices such as the modern lamp are much more convenient to use than their counterparts of the 1840's.

Products of the 1840’s: Horse-drawn carriage, Oil lamp, Flatiron, Handsaw, Needle and thread, Folding fan, Washboard, and Wood-burning stove.
Products of the 1990’s: Car, Electric lamp, Electric iron, Power saw, Sewing machine, Air conditioner, Washing machine, and Microwave oven.

What is Technology?

Technology is known as the application of scientific knowledge for practical purposes, especially in industry. "advances in computer technology" (a) machinery and equipment developed from the application of scientific knowledge, and (b) the branch of knowledge dealing with engineering or applied sciences.

Technology refers to all the ways people use their in­ventions and discoveries to satisfy their needs and de­sires. Ever since people appeared on the earth, they have had to work to obtain food, clothing, and shelter. They have also had to work to satisfy their desire for lei­sure and comfort. Through the ages, people invented tools, machines, materials, and techniques to make work easier. They also discovered water power, electric­ity, and other sources of power that increased the rate at which they could work. Technology thus involves the use of tools, machines, materials, techniques, and sources of power to make work easier and more pro­ductive. Modern communications and data processing also rely on technology, especially electronics.

Many people call the age we live in the age of tech­nology. Yet people have always lived in a technological age because they have always had to work to obtain most of life's necessities and many of its pleasures. Technology thus includes the use of both primitive and highly advanced tools and methods of work. But when people speak of technology today, they generally mean industrial technology— the technology that helped bring about our modem society.

Industrial technology began about 200 years ago with the development of the steam engine and power-driven machines, the growth of factories, and the mass produc­tion of goods. As industrial technology advanced, it af­fected more and more aspects of people's lives. For ex­ample, the development of the car influenced where people lived and worked and how they spent their lei­sure time. Radio and television changed entertainment habits, and the telephone revolutionized communica­tion. Today, industrial technology helps people achieve goals that few would have thought possible a hundred years ago. It gives people the means to conquer hunger and to cure or prevent many diseases. It enables them to transport goods and passengers swiftly and easily to any place on the earth. They can even leave the earth, travel through space, and set foot on the moon.

Science attempts to explain how and why things hap­pen. Technology is concerned with making things hap­pen. Since 1850, science has contributed much to mod­ern technology. However, technology has often contributed to science, for example, by providing suit­able tools for observation. In addition, not all technol­ogy is based on science, nor is science necessary to all technology. For example, people made objects of iron for hundreds of years before they learned about the changes that occurred in the structure of the metal dur­ing iron making. But some modern technologies, such as nuclear power production and space travel, depend heavily on science.

The word technology is sometimes used to describe a particular application of industrial technology, such as medical technology or military technology. Each of the various specialized technologies has its own goals and its own tools and techniques for achieving those goals. The engineering profession is responsible for much of today's industrial technology (see Engineering).

Industrial technology enables people to live in greater security and comfort than ever before. But only a small part of the world's population enjoys the full benefits of advanced modern technology. In addition, nations with advanced technologies have found that cer­tain undesirable effects, such as air and water pollution, have accompanied technological growth. Technology also enables people to produce more powerful weap­ons, thus adding to the destructiveness of war.

This article describes technology's benefits and unde­sirable effects. It also discusses the problems people face in trying to combat these effects. The development of technology largely parallels the history of inventions and discoveries, which is traced in the article on Inven­tion. Detailed information on the development of tech­nology in specific areas can be found in the History sec­tions of such articles as Agriculture, Medicine, and Transportation.

Benefits of technology

Technology has helped people gain a degree of con­trol over nature and build a civilized way of life. The ear­liest human beings had little control over nature. They had only simple tools and did not know how to rear ani­mals or cultivate plants. Instead, they obtained food by hunting, fishing, and gathering. They had no permanent homes and only animal skins for protection against cold. The sun and moon were their Only sources of light. About 800,000 years ago, people discovered how to make fire and so could provide themselves with heat and light wherever they went. Still, they made little no­ticeable impact on their environment.

About 10,000 years ago, people learned how to rear animals and grow crops. The development of farming led them to settle down in small groups. Then, partly be­cause agriculture produced surplus food, the popula­tion grew. In time, towns and cities developed. Many people became free to pursue kinds of work other than food production. Classes of warriors, priests, craft- workers, and merchants developed. This division of la­bour helped make civilization possible.

Through the ages, technology has benefited people in four main ways. First, it has increased their produc­tion of goods and services. Second, it has reduced the amount of labour needed to produce goods and serv­ices. Third, it has made labour easier. Fourth, it has given people higher living standards.

Increased production. Through technology, people have achieved a tremendous increase in the production of goods and services. In the mid-1800's, for example, people and animals were the main source of power on farms. Farmers laboured from dawn to dusk, yet one farmer produced enough food for only about four peo­ple. In the early 1900's, more and more farmers in indus­trial countries began using tractors and other machines powered by diesel fuel or electricity. Today, machines do most of the work on most farms in industrial coun­tries. As a result of machinery, fertilizers, and other ad­vances in agricultural technology, one farmer today may produce enough food for about 100 people. Similar de­velopments have occurred in manufacturing, mining, and other industries. Most workers today produce many times more goods than they did a hundred years ago.

Reduced labour. Powered machines have increased production. But they have also reduced the amount of labour needed to produce goods and services and so have increased productivity. Increased productivity gives workers more leisure time. In the early 1800's, for example, most factory work was done by hand or hand- operated machines. Workers laboured 12 to 16 hours a »y day, six days a week. Few people were able to take a holiday. Today, powered machinery has largely replaced hand labour in factories. Many factories also use mass production techniques. As a result, the amount of labour needed to produce manufactured goods has decreased sharply. Today, factory employees in many countries work only eight hours a day, five days a week. They also receive paid leave for holidays.

Easier labour. Technology has enabled people to produce more goods and services with less labour. It has also made labour easier and safer. Coal mining pro­vides an example. In the early 1900's, miners toiled all day with pick and shovel to produce a few tons of coal. The mines were dark, poorly ventilated, and dangerous. Today, mining is still dangerous. But better lighting and ventilation and improved safety devices have reduced the hazards. The work itself is easier and more produc­tive. Machines perform most of the hard labour. The op­erator of a coal-mining machine can dig about 1 metric ton of coal a minute.

Farm machines, such as these combines, and other advances in agricultural technology make farm work easier. Such machines and methods also help farmers produce larger amounts of food.

Higher living standards have resulted from the in­creased production of goods and services. The indus­trial nations produce more goods and services than other countries and have the world's highest standard of living. Most people in industrial nations are better fed, clothed, and housed and enjoy a healthier, more com­fortable life than any other people in history. Above all, technology has increased human life expectancy— the number of years a person can expect to live. Improved public health practices have ended the plagues that once swept through many countries. Better health care and nutrition have also reduced the number of deaths among infants. In 1900, many people did not live past the age of 50. Today, many people live for more than 75 years (see Life expectancy).

Undesirable effects of technology

The advance of technology has benefited people in numerous ways, but it has also created serious prob­lems. These problems have arisen mainly because tech­nologies were put to use without considering the possi­ble harmful effects. For example, many people wel­comed the development of the car in the late 1890's and early 1900's. They believed that cars would be quieter and less smelly than horses. But as more and more cars came into use, the noise of roaring traffic proved more annoying than the clatter of horse hoofs. Car exhaust fumes proved worse than the smell of horse manure. The fumes polluted the air with carbon monoxide gas and other impurities and so threatened human health. Also, cars cause even more traffic congestion in cities, and car travel can be more time-consuming than travel on horseback. The ever-increasing production of cars used up iron and other natural resources.

This section discusses four major undesirable effects of technology. They are: (1) environmental pollution, (2) the depletion of natural resources, (3) technological un­employment, and (4) the creation of unsatisfying jobs.

Environmental pollution is one of the most harmful effects of industrial technology. Most industrial coun­tries face problems of air, water, soil, and noise pollu­tion. Motor vehicles cause most of the air and noise pol­lution in these countries. But many other products as well as many processes of technology also pollute the environment. For example, certain insecticides pollute the soil and water, and endanger plant and animal life. Factory smoke and wastes also contribute greatly to air and water pollution. In many countries, power plants that burn oil or other fuels to generate electricity add millions of tons of pollutants to the air annually. Junk­yards, opencast mines, logging operations, and motor­ways disfigure the natural environment. See the article on Environmental pollution for a discussion of technol­ogy's harmful environmental effects.

The depletion of natural resources. The rapid ad­vance of technology threatens the supply of natural re­sources. For example, the use of electrically powered machinery in industrial countries has greatly increased factory production. But at the same time, it has reduced the supply of oil and other fuels used to produce elec­tricity. These fuels cannot be replaced after they are used. As power production increases, the supply of fuels decreases. Power production increased so much during the 1950's and 1960's that some countries began to experience a fuel and power shortage during the 1970's.

Some experts argue that the use of hydroelectricity in some countries also depletes natural resources. Usually the damming of rivers transforms fertile agricultural land into lakes and the dams' effectiveness is gradually reduced by silting (the build up of soil washed down in a river).

Technological unemployment is a type of unem­ployment that sometimes results from advances in tech­nology. The most common type of technological unem­ployment occurs as a result of mechanization— that is, the replacement of human workers with machines. Since the late 1950's, many factories and offices have in­troduced computers and other machines as part of a self-operating system called automation. Automated ma­chines perform many tasks formerly done by workers, and so automation has caused some unemployment. But automation also has helped a number of industries ex­pand. As a result, these industries have been able to provide new jobs for displaced workers. Technological unemployment, however, remains a threat to workers in many industries. See Unemployment (Structural unem­ployment).

The creation of unsatisfying jobs. Some tasks re­quired by industrial technology fail to give workers a feeling of accomplishment. For example, most factory workers make only a part of the finished product. As a result, they may lack the feeling of pride in their work that comes from creating an monotonous as well as demanding.

The challenge of technology

Modern technology presents enormous challenges. One of the chief challenges is to combat the undesirable effects of existing technologies. Another is to prevent similar effects in the development of new technologies. Still another challenge is to spread technology's benefits to the people of developing countries.

Combating undesirable effects. Some of technolo­gy's undesirable effects are hard to remedy. For exam­ple, it is difficult to make an unsatisfying job satisfying. But automation will continue to free many workers from routine, monotonous jobs. Some of these workers may then face the hardships of unemployment. But with help from industry and government, they can be retrained to fill more highly skilled and possibly more interesting jobs. See Automation (Automation and jobs).

Industries can do much to combat environmental pol­lution and the depletion of natural resources. One way is by developing substitute technologies for those that produce harmful effects. Car makers, for example, can help curb air pollution by installing a catalytic converter (a type of filter) to purify the emissions from car exhaust. Manufacturers can help conserve resources by recy­cling. In recycling, raw materials are recovered from waste products and used to make new products (see En­vironmental pollution [Recycling]).

Developing a substitute technology can be costly. An industry may need to hire additional experts or invest in expensive equipment. Most industries that develop a substitute technology pass the cost on to buyers in the form of higher prices. Some industries choose not to spend the money to develop a substitute technology. Recycling materials can also be more costly than the use of traditional resources. But in many cases, the choice is too serious to be left to industries because the health of an entire community may be affected.

Substitute technologies may also have undesirable ef­fects. For example, nuclear power plants have several advantages over fuel-burning plants in producing elec­tricity. Nuclear plants can produce large amounts of electricity using only small amounts of raw materials. They also do not pollute the air as do fuel-burning plants. But nuclear plants release hot water into lakes and rivers. This causes thermal pollution, which harms water plants and animals. Scientists and engineers are working to solve this problem. For example, many nu­clear plants have installed cooling towers, which use air to cool the hot water they produce. Some companies re­cover the waste heat produced by industrial processes for the heating of buildings.

Preventing undesirable effects. Some experts be­lieve that most harmful effects of technology can be pre­vented. According to this view, any proposed large- scale technology should be thoroughly tested and then evaluated before it is put into use. Such an evaluation is called a technology assessment.

The purpose of an assessment is to discover in ad­vance all the possible good and bad effects that a new technology may have on society and the environment. An assessment might show that the benefits of a new technology outweigh any undesirable effects. Or it might show that the undesirable effects would be so harmful that they outweigh any benefits.

Some experts doubt the value of technology assess­ment. They believe that it is not possible to discover all the undesirable effects of a technology before it is put into use. They also fear that technology assessments will block scientific and technological progress.

Spreading the benefits of technology. Technolo­gy's benefits are limited largely to the industrial nation: But even in these nations, the benefits of technology are not evenly distributed. Many families in the industrial countries lack ail but the bare necessities of life.

The developing nations of the world enjoy few of technology's benefits. Also, the people of these coun­tries want the goods and services that technology has made available to industrial nations. The transfer of technological knowledge from industrial to developing na­tions is one of today's chief challenges.

As technology advances in developing countries, it will probably produce some harmful effects. Advanced technology will probably also continue to create prob­lems in the industrial countries. But technological achievements in the past show that people have the in­telligence, imagination, and inventive skill to deal with present and future problems created by technology.

Related articles -See Engineering, Industry Invention, and Manufacturing

See also the following articles: Agriculture, Environmental, Machine, Assembly line, pollution, Machine tool, Automation, Factory, Mass production,

Building, trade, Industrial Revolution Mining, Labour force.

Outline

Benefits of technology

Increased production

(A) Reduced labour

(B) Higher living standards

(C) Easier labour

Undesirable effects of technology

(A) Environmental pollution
(B) The depletion of natural resources

Helicopter

Types of helicopters - (1) Single-Rotor, (2) Tandem-Rotor, and (3) Coaxial-Rotor Helicopter.

A heavily armed attack helicopter on a mission          

A helicopter hovering over a logging site

A transport helicopter flying supplies to an oil rig      

A business helicopter landing on a city rooftop

Helicopters can do jobs that aeroplanes cannot do. Unlike planes, military attack helicopters can turn instantly to fire weapons in almost any direction. Helicopters can hover in midair and take off and land in small areas, such as forest clearings, drilling platforms, and rooftops.

Helicopter rescue missions have saved the lives of thousands of people. A coast guard helicopter above has picked up the crew members from a sinking ship.

Helicopter rescue missions have saved the lives of thousands of people. A coast guard helicopter above has picked up the crew members from a sinking ship.

Crop-dusting by helicopter enables farmers to spray agricultural chemicals exactly where they are needed. This specially equipped helicopter is spraying a field with insecticide.     

An antisubmarine helicopter, armed with torpedoes, takes off from a navy ship. Such helicopters carry electronic devices to locate and track submarines.

A rotor blade's shape creates lift. As the blade moves, air flows faster over its curved upper surface than under its flat lower surface. Air pressure is thereby reduced over the blade but unchanged under it. This difference in pressure produces lift.

Greater lift can be created by increasing the angle of attack- the angle the rotor blade makes with the air flowing past it. Increasing the angle causes air to push against the bottom of the blade, which in­creases the air pressure and thereby the lift.

Helicopter controls. Moving the collective pitch lever makes the helicopter climb, hover, or descend. Tilting the control col­umn causes forward, backward, or sideways flight. Pushing the rudder pedals controls the direction the helicopter points. 

Piloting a helicopter - A pilot flies a helicopter by varying the pitch (angle) of the rotor blades. The lift of the main rotor counteracts gravity. The force of the tail rotor counteracts torque, a force that tends to spin the air­craft in the direction opposite to that of the main rotor. In the diagrams below, the pitch of the blades is indicated by the thickness of the circles showing the area swept by the rotor.

The first practical single-rotor helicopter was built and flown by Igor Sikorsky. Its first flight, was in 1939.

Helicopters in combat were first used on a massive scale by United States armed forces during the Vietnam War (1957-19751).

An experimental compound helicopter has coaxial rotors to provide lift. However, it uses jet engines for forward movement. Such aircraft can fly much faster than regular helicopters.

What is a Helicopter?
Helicopter is a type of aircraft that derives both lift and propulsion from one or more sets of horizontally revolving overhead rotors. It is capable of moving vertically and horizontally, the direction of motion being controlled by the pitch of the rotor blades.
Facts, History and Types. Helicopter, aircraft with one or more power-driven horizontal propellers or rotors that enable it to take off and land vertically, to move in any direction, or to remain stationary in the air. Other vertical-flight craft include autogiros, convertiplanes, and V/STOL aircraft of a number of configurations...

Helicopter is an aircraft that is lifted into the air and kept aloft by one or two powerful whirling rotors. A hel­icopter rotor resembles a huge propeller that is parallel to the ground. However, the rotor is actually a rotating wing. The name helicopter refers to the rotor. It comes from the Greek words helix, meaning spiral, and pteron, meaning wing. Nicknames for the helicopter include "chopper," "eggbeater," and "whirlybird."

A helicopter can fly straight up or straight down, for- ward, backward, or-sideways. It can even hover (stay in one spot in the air). Unlike most aeroplanes, helicopters need no runway. They can take off and land in a very small space. In addition, helicopters can fly safely at much slower speeds and lower altitudes than aero­planes. However, they cannot fly as fast as most planes. Most helicopters cannot exceed 320 kilometres per hour. At faster speeds, strong vibrations develop that could damage the rotor blades. Helicopters also use more fuel than aeroplanes to travel the same distance, and so are less economical than aeroplanes. In general, helicopters can fly for only two to three hours-or less than 1000 kilometres—without refuelling. Aeroplanes can travel much further without refuelling.

Helicopters range in size from tiny, single-seat mod­els to huge transports that can carry two trucks in their cargo hold. The heaviest helicopter is the Mil Mi-26, built by the Soviet Union. It weighs 28 metric tons and can carry 20 metric tons of cargo.

Uses of helicopters

Helicopters can be used for many tasks that cannot be performed by other types of aircraft, because they are able to hover in midair and take off and land in small areas. They are particularly useful (1) for rescue mis­sions, (2) for aerial observation, (3) for transportation and construction work, (4) for agricultural and forestry oper­ations, and (5) for military missions.

For rescue missions. Many early developers of heli­copters intended them to be used for saving lives. A hel­icopter can hover above the scene of a disaster. A sling or harness can then be lowered from the craft to endan­gered people below. They are then pulled up and flown to safety. Helicopters have been used to pluck people from burning skyscrapers, sinking ships, and rising floodwaters. They have flown stranded mountain climb­ers and injured skiers to safety. Serving as flying ambu­lances, helicopters can land near car or aeroplane crashes and rush the injured to hospitals. Helicopters can also deliver food and medicine to areas that other vehicles cannot reach because of earthquakes, floods, or storms.

For aerial observation. In many cities, police use helicopters to trail fleeing suspects and direct police cars on the ground. Law enforcement agents in helicop­ters look for lost people and escaped convicts. They may patrol national borders on the lookout for smugglers and illegal immigrants. Helicopters are also used to patrol motorways and identify speeding cars.

Many radio and television stations use helicopters to cover news events from the air. In large cities, helicop­ter pilots observe the flow of traffic and broadcast radio reports warning drivers of traffic jams. Film companies often film from helicopters to give audiences a bird's- eye view of a scene. Helicopter pilots fly low along pipe­lines, railway tracks, and power lines to inspect them for damage.

Helicopters are used to explore wilderness areas, to survey land, and to help locate oil and other resources. From helicopters, scientists count wildlife populations and chart the migration routes of wild animals. Some fishing fleets use helicopters to spot schools of tuna.

For transportation and construction work. Heli­copter transportation is expensive. However, the con­venience of helicopter flight makes "choppers" ideal transport vehicles for certain uses. The flexibility, secu­rity, and speed of helicopter travel have made it a major method of transportation for political leaders in many countries. Helicopter travel saves business executives time that they otherwise might waste in using slow-moving ground transportation. From heliports (airports for helicopters) on city office buildings, business execu­tives may fly directly to nearby cities for meetings.

Helicopter service is essential to many offshore oil-drilling operations. Numerous offshore wells are in rough ocean waters that make it hazardous to bring in replacement crews and supplies by ship. However, heli­copters can land on the drilling platforms and so pro­vide much faster and safer delivery than ships.

Helicopters are often used to transport cargo that is too large or awkward for other vehicles to haul. The cargo is carried in a sling hanging below the craft.

Powerful helicopters are used in construction work as "flying cranes." Workers in helicopters install aerials and huge air conditioners on top of tall buildings and erect preassembled electric power transmission towers. Workers also use helicopters to pour concrete in hard- to-reach places and to put long bridge sections in posi­tion.

For agricultural and forestry operations. Farmers use helicopters to spread seeds, fertilizers, weedkillers, and insecticides over large areas. Instead of building roads, some companies that manufacture forest prod­ucts depend on helicopters to transport logging crews into and out of forests and to carry out logs.

For military missions. In the armed forces, helicop­ters serve as flying ambulances and as troop transports. Powerful military helicopters carry artillery to key battle positions and fly jeeps, tanks, and other equipment wherever they are needed. Helicopters equipped with electronic gear pick up and disrupt enemy communica­tions signals. The armed forces also use helicopters to observe the movements of enemy troops and ships. Many naval helicopters have devices to locate and track submarines. They may also be armed with depth charges, missiles, or torpedoes. Army attack helicopters may carry bombs, cannons, machine guns, or missiles. Their main targets are enemy tanks.

Types of helicopters

Single-rotor helicopters are the most common type of helicopters. A single-rotor helicopter has one main rotor mounted above its body. Although such an aircraft is called a single-rotor helicopter, it also has a second, smaller rotor mounted on its tail. The main rotor may have from 2 to 8 blades. It provides the helicopter's lifting power. The tail rotor has from 2 to 13 blades. It is mounted vertically on either side of the tail and so spins at a right angle to the main rotor. The tail rotor is used to control direction. It also overcomes the tendency of the helicopter to spin around in the direction opposite to that of the main rotor.

Twin-rotor helicopters have two main rotors. The rotors turn in opposite directions and so eliminate the need for a tail rotor. Two basic types of twin-rotor heli­copters are widely used: tandem-rotor helicopters and coaxial-rotor helicopters. A tandem-rotor helicopter has a main rotor mounted above each end of its body. A co-axial-rotor helicopter has one rotor above the other. The rotors are mounted above the middle of the helicopter's body. The shaft of the upper rotor turns inside the shaft of the lower rotor.

How helicopters fly

Lift is the force that causes an aircraft to overcome gravity, climb into the air, and stay aloft. Most aircraft rely on wings to produce lift. An aeroplane has fixed (im­movable) wings that create lift as the aeroplane moves forward. Helicopter rotor blades are rotary wings. An engine turns the rotor, and the blades generate lift as they whirl through the air.

The special shape of wings helps them create lift. A wing's upper surface is curved, and its lower surface is less curved or flat. As a wing moves or whirls through the air, air flows over and under the wing. In the same amount of time, the air flowing over the curved upper surface travels farther than the air flowing under the wing. The air thus flows faster over the wing than under it. This difference in air speed creates a difference in air pressure above and below the wing. There is less pres­sure on the upper surface than on the lower surface. Be­cause air is pushing more strongly against the bottom of the wing than against the top, lift is created. For addi­tional information, see the article Aerodynamics (Princi­ples of aerodynamics).

Helicopter pilots, like aeroplane pilots, can control the amount of lift by changing the angle that the wings make with the airflow. This angle is called the angle of attack. You can demonstrate the relation between lift and the angle of attack by using a kite to serve as a sim­ple wing. Hold the kite flat and point it into the wind. If you then slightly raise the front of the kite, you increase the angle of attack. You will feel a force trying to push the kite upward. This force is the lift created by the wind as it pushes against the bottom surface, if you decrease the angle of attack, the force becomes weaker.

Piloting a helicopter. The pilot of a single-rotor heli­copter operates three basic controls inside the cockpit.

(1) The collective pitch lever makes the helicopter climb, hover, or descend. (2) The control column, also called the cyclic pitch control, causes it to fly forward, back­ward, or sideways. (3) The rudder pedals swing the tail around so that the helicopter can turn. Each control var­ies the pitch (angle) of the main rotor or tail rotor blades.

A system of cables, rods, and other devices leads from the controls in the cockpit to the rotor blades.

Climbing, hovering, and descending. The pilot's left hand moves the collective pitch lever up and down. By raising the lever, the pilot increases the pitch of all main rotor blades equally. The increased pitch, in turn, in­creases the lift generated by the spinning rotor. When lift exceeds the force of gravity, the helicopter goes straight up. After reaching a particular altitude, the pilot may want to hover. The pilot then lowers the lever to de­crease the pitch of the rotor blades and so reduce the amount of lift. When the rotor's lifting force has been reduced just enough to counteract the pull of gravity, the craft will maintain a constant altitude. To de­scend, the pilot lowers the collective pitch lever farther, thereby decreasing the lift. When lift becomes weaker than the force of gravity, the craft descends.

Flying forward, backward, and sideways. The pilot's right hand operates the control column. The control col­umn is a stick between the pilot's knees. It can be tilted in any direction. The helicopter moves in whatever di­rection the pilot tilts the column.

When the control column is tilted, the pitch of the main rotor blades alternately increases and decreases as they sweep through opposite sections of their circular path. To fly forward, the pilot pushes the column ahead. This causes the pitch to be greatest just before the blades pass over the tail. The blades have the least pitch just before they reach the nose. These changes in pitch cause the rotor blades to rise slightly in the rear. The rotor then tries to pull the helicopter both upward and ahead. Gravity counteracts the upward pull, however, and so the aircraft moves forward in level flight.

To fly backward, the pilot pulls back on the control column. This gives the blades the most pitch as they ap­proach the nose and the least pitch as they approach the tail. The nose rises, the tail dips, and the helicopter flies backward. The aircraft can be made to fly sideways in a similar manner.

Turning. As a helicopter's main rotor spins in one di­rection, it creates a force that pushes against the body of the craft in the opposite direction. This twisting force is called torque. It must be overcome or the helicopter will be out of control and simply turn in circles.

The main rotor of a single-rotor helicopter spins in a counterclockwise direction, and so the push of the torque is clockwise. The pilot of a single-rotor craft uses the tail rotor to counteract torque and to change direc­tion. The pilot controls the tail rotor by stepping on two rudder pedals. If neither pedal is depressed, the tail rotor blades spin at just the right pitch to produce ex­actly enough sideways force to counteract the torque. The helicopter then points straight ahead. To swing left, the pilot steps on the left rudder pedal, thereby increas­ing the pitch of the tail rotor blades. The increased force of the rotor pushes the tail in the direction opposite to the clockwise push of the torque. The helicopter then turns to the left. To turn right, the pilot depresses the right rudder pedal and so decreases the pitch—and thus the force—of the tail rotor blades. The torque itself then swings the tail in a clockwise direction, which turns the helicopter to the right.

On a twin-rotor helicopter, one main rotor turns clockwise and the other turns counterclockwise. As a re­sult, the torque generated by one rotor cancels out that generated by the other. The pilot turns the craft by changing the pitch of the main rotors.

Development of the helicopter

Early designs and experiments. The earliest known mention of a rotor-powered flying machine appears in a Chinese text written about A.D. 320. The design of this machine may have been based on a Chinese toy called the flying top. Such toys flew by means of feather rotors. In 1483, the great Italian artist and scientist Leonardo da Vinci sketched a design for a helicopter. It had a large screwlike wing made of starched linen. In 1784, two Frenchmen named Launoy and Bienvenu built the first model helicopter in Europe that could fly. Based on the Chinese flying top, it had two rotors made of feathers. Throughout the 1800's, inventors in Europe and the United States experimented with model helicopters. The steam engines and electric motors of that time were too weak or too heavy to power a full-sized helicopter.

By the early 1900's, small, powerful petrol engines had been developed that made manned helicopter flight possible. The first manned flight took place in 1907. The craft was a four-rotor helicopter built by Louis Breguet, a French inventor. The helicopter lifted one of Breguet's assistants 61 centimetres into the air for a minute. Assist­ants on the ground steadied the helicopter during the flight. Later in 1907, a French mechanic named Paul Cornu made the first free flight in a helicopter. Fie flew his tandem-rotor aircraft to a height of about 2 metres for about 20 seconds.

The first practical helicopters. Early helicopters were difficult to control, and their flight was wobbly. In 1935, Breguet and another Frenchman, Rene Dorand, built a coaxial-rotor helicopter that was easier to control and flew far more steadily. In 1936, Heinrich Focke, a German inventor, built a twin-rotor helicopter that was even further advanced. The following year, it reached a speed of 122 kilometres per hour and an altitude of about 2,400 metres. It could stay aloft for 1 hour and 20 minutes.

The first flight of a practical single-rotor helicopter took place in the United States in 1939. The craft was built and flown by Igor I. Sikorsky, a Russian engineer who had moved to the United States in 1919. The British and the U.S. armed forces used an improved version of Sikorsky's helicopter during World War II (1939-1945).

Further improvements. During the mid-1900's, the military use of helicopters began to increase greatly, which led to major improvements in their design. Helicopters had been used mainly for patrol and rescue mis­sions in World War II. New tasks for the helicopter dur­ing the Korean War (1950-1953) included armed observa­tion of enemy positions and strength and transporting troops and supplies to hard-to-reach areas. During the Vietnam War (1957-1975), thousands of armed U.S. attack helicopters flew combat missions.

The ever-expanding military use of helicopters en­couraged the development of faster, larger, and more powerful craft. In the 1940's and 1950's, engineers adapted the jet engine for use in helicopters. Jet engines were lighter and more powerful than the previous en­gines used to turn the rotor shafts. They enabled heli­copters to fly faster and higher and to carry heavier loads. In addition, the use of new construction materials made helicopters lighter, safer, and stronger. For exam­ple, metal or wooden rotor blades were replaced by longer-lasting plastic blades. Such improvements also made helicopters suitable for more civilian uses.

Recent developments include efforts by manufac­turers to simplify the complicated operation of helicop­ters and to increase their speed. One manufacturer has developed a single-rotor helicopter that needs no tail rotor. Instead, the craft uses jets of air to counteract torque and to change direction. Attempts to increase the speed of helicopters have led to the development of ex­perimental compound helicopters. These vehicles do not depend entirely on rotors to provide forward move­ment as well as lift. Instead, compound helicopters also have jet or propeller systems to help push or pull them ahead. One compound helicopter has reached the speed of 555 kilometres per hour. Related articles: Aerodynamics, Sikorsky, Igor I; Autogiro; Cayley, Sir George; and V/STOL

Outline:

Uses of helicopters: For rescue missions; For aerial observation; For agricultural and forestry operations; For transportation and for construction work; and For military missions

Types of helicopters: Single-rotor helicopters; and Twin-rotor helicopters

How helicopters fly: Lift, and Piloting a helicopter

Development of the helicopter

Questions

What kind of wings does a helicopter have?

How are helicopters used in the construction industry?

What is a tandem-rotor helicopter? A coaxial-rotor helicopter? Who built and flew the first practical single-rotor helicopter? What are some military uses of the helicopter?

Why does a single-rotor helicopter have a tail rotor?

What is a compound helicopter?

In what ways can a helicopter fly that an aeroplane cannot?

What happens when a helicopter pilot raises the collective pitch lever?

Why is helicopter service essential to many offshore oil-drilling operations?

Helicopter Crash

Update: Victim identified in Skagway helicopter crash

A Skagway helicopter pilot is dead following a crash outside Skagway Friday evening. The pilot was 59-year-old Christopher Maggio of Skagway. Maggio was the only person on board. According to an Alaska State Trooper report, the U.S. Coast Guard contacted troopers Friday evening around 8:30 to report that a helicopter had gone down near the upper portion of the Denver Glacier, 6 miles east of Skagway.

Norway helicopter crash: 13 killed near Bergen - BBC News

BBC - Apr 29, 2016 - Thirteen people are presumed dead after a helicopter crashed west of the Norwegian city of Bergen, rescuers say. ... Meanwhile, Norway's civil aviation authority has imposed a flight ban on the type of helicopter that crashed - the Eurocopter (EC) 225L Super Puma. ... The aircraft was ...

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The Straits Times - 2 days ago - KUCHING (THE STAR/ASIA NEWS NETWORK) - The fifth body from ahelicopter crash in Sarawak which killed a deputy Cabinet minister has been recovered on Saturday (May 7). ... Four bodies including that of Deputy Plantation Industries and Commodities Minister Noriah Kasnon had already ...

New debris found, search on for last victim of Sarawak helicopter crash

The Straits Times - 20 hours ago - KUCHING (THE STAR/ASIA NEWS NETWORK) - New debris believed to be from the Sarawak helicopter that crashed and killed a Malaysian ...

Norway helicopter crash kills - CNN.com

CNN - Apr 29, 2016 - (CNN) A helicopter carrying workers from an oil platform to the mainlandcrashed off the coast of Hordaland, Norway, on Friday, most likely ...

Helicopter pilot dies in crash in Skagway | Alaska Dispatch News

Alaska Dispatch News - 1 day ago - A pilot for a Southeast Alaska charter and flightseeing company was killed when the helicopter he was flying crashed near a glacier in Skagway ...

WBAY - Pilot killed in helicopter crash was stringing wire for American ...

WBAY‑TV: 4 days ago - A pilot helping with the installation of transmission lines was killed when the helicopter crashed in Manitowoc County Wednesday morning.

Officials ID victims of medical helicopter crash in Pinal County - CBS 5 ...

Pinal County Sheriff Paul Babeu said the helicopter was returning to Globe from Phoenix-Mesa Gateway Airport when it crashed in very rugged terrain in the ...

Helicopter Crash On French Reality Show Kills 10, Including Olympic ...

A French reality series has suffered a devastating accident. On Monday, 10 people died when two helicopters collided into one another during the creation of the ...