Category FLIGHT and M ОТІOIM

irds are warm-blooded vertebrates with wings instead of forelimbs or arms. Birds are the only animals with feathers. These strong but delicate structures keep a bird warm and help it to fly.

The Study of Flight

The first people to dream of flying undoubtedly gazed at birds. Birds are truly masters of the air, although other animals, such as insects and bats, also fly. Scientists of old must have watched a bird or a bee and puzzled over how these creatures flew. Today’s scientists have analyzed the aerodynamics of the bumblebee and are amazed that this insect can even get off the ground!

People in ancient times thought they could imitate bird flight. It looked so easy-if a swan or a goose could fly simply by flapping its wings, why not a human? So inventors tried to fly by strapping feathery wings to their arms and leaping from high towers, waving their arms. Sadly, like Icarus in the ancient Greek myth, they crashed to the ground. A machine called an ornithopter can fly by flapping its wings, but a person cannot.

Boeing entered the jet age in 1947 with the B-47 Stratojet, a swept-wing bomber with six jet engines. Its “big brother” was the B-52 Stratofortress (1952), which became the U. S. Air Force’s primary strategic bomber. The B-52’s success showed that manned airplanes still had roles in the missile age and that a good design could be updated several times. In 1952, Boeing also built its first missile, the Bomarc.

Boeing was the first manufacturer in the United States to see the potential in commercial jet travel. In 1952 Boeing’s designers began work on a jet airliner, known as “Dash-80” to employees but marketed as the Boeing 707. Like most Boeing designs, it built on earlier experience: the 707’s wings were similar to the wings of the B-47, but it had four engines, each one separately mounted on an under­wing pylon.

О A Boeing 777 was on display at the Paris Air Show in France in 2005. The 777, released in 1994, was the first Boeing civil airplane with a fly-by-wire (electronic) control system.

William Boeing, the company founder, lived to see the new 707 fly in 1954; he died two years later. In 1958 the 707 started transatlantic services, capturing a lead for Boeing in the com­mercial jetliner market that the company retained for a half century. The 707 had a cruising speed of 605 miles per hour (973 kilometers per hour) and could carry 147 passengers over a distance of 5,755 miles (9,260 kilometers). Boeing’s 707 design led to other successful air­planes, such as the E-3A Sentry AWACS airplane. It also resulted in the develop­ment of the KC-135 tanker, used by the U. S. Air Force for inflight refueling.

Fighter cockpits are different from other aircraft cockpits. There is only enough room in a fighter’s nose for one seat for one pilot. If a second crewmember is needed, perhaps to operate the weapons systems, he or she sits behind the pilot.

The cockpit has a bubble canopy to give the fighter pilot a good all-around view. The pilot sits in an ejection seat. If the plane is about to crash, the pilot fires a rocket under the seat, which blasts it clear of the plane. The pilot then lands safely by parachute.

There is no control yoke in a fighter’s cockpit. The pilot steers by means of a control stick, or joystick. Moving the joystick to one side makes the plane roll

О Information from the Head-Up Display (HUD) is super­imposed in the pilot’s field of view in the cockpit of an F/A-18C Hornet fighter plane as it prepares for takeoff. Four other Hornets are lined up on the runway in front of the plane.

to that side. Pushing it for­ward makes the plane dive, and pulling it back makes the plane climb.

A fighter pilot does not always have time to look down at the instruments or to let go of the joystick or throttle to operate other controls. The cockpit is designed to solve both of these problems. A Head-Up Display, or HUD, projects important information onto a glass plate right at eye level so the pilot can keep looking ahead. The information seems to float in midair. Some HUDs are even built into the pilot’s helmet.

The pilot does not have to let go of the flight controls, because the buttons and switches that control the cockpit displays and other systems are all on the throttle and joystick. This is called Hands On Throttle-and-Stick (HOTAS).

HUDs and HOTAS are now built into some cars. A handful of cars project the car’s speed onto the windshield so the driver can see it without looking down at the instruments. Some racecars have buttons and switches for the most important systems built into the steering wheel, so the driver does not have to let go of the wheel to operate them.

Helicopters

Helicopters can fly up, down, sideways, and even backward as well as forward, so the pilot needs a good view all around the aircraft. Helicopter cockpits must therefore have large windows.

Helicopter cockpits have four main controls. They are: cyclic pitch control, rudder pedals, collective pitch control, and throttle. The cyclic pitch control is a joystick that steers the helicopter. The rudder pedals turn the aircraft to point in the right direction. The throttle con­trol is a twisting device on the collective pitch lever. Twisting the throttle control increases the engine speed, and raising the collective pitch control lever makes the helicopter rise into the air.

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SEE ALSO:

• Altitude • Control System

• Fighter Plane • Helicopter • Pilot

• Space Shuttle

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Type: Commercial transport, medium – range airliner.

Manufacturer: Douglas.

First flight: December 17, 1935.

Primary use: Widely used by airlines.

he Douglas Commercial 3, or DC-3, was one of the most successful aircraft ever built. It has been called the greatest airplane of all time because it made air travel popular with passengers and profitable for airlines.

Day and Night Passenger Plane

The DC-3 was born when American Airlines asked the manufacturing com­pany Douglas to design a “stretched” version of their DC-2 airliner that would offer comfortable sleeping accommoda­tion. The result was the DST (Douglas Sleeper Transport), or Skysleeper, first flown in December 1935. This plane pro­vided hotel-style luxury, with fourteen sleeping berths converted from folded – down seats.

From this model, Douglas produced a day version of the airplane, which it called the DC-3. The new plane was fitted with twenty-one to twenty – four seats, ten more than the standard DC-2. The DC-3 was an immediate suc­cess. It was delivered to American Airlines in August 1936 and operated a regular flight schedule between New

TECH^TALK

RELIABLE AND STRONG

The secret of the DC-3 was its relia­bility, excellent safety record, and ease of maintenance. The DC-3 had a rugged all-metal airframe-only the control surfaces were fabric-cov­ered. The aircraft had a very strong, almost circular cross-section, and strong cantilever wings that were slightly swept back. It had a single elevator and rudder, retractable landing gear, and an automatic pilot.

Its engines were as reliable as its strong frame.

Cruising speed: 207 miles per hour (333 kilometers per hour).

Ceiling: 23,000 feet (7,000 meters). Maximum range: 2,125 miles (3,420 kilometers).

Maximum takeoff weight: 25,000 pounds (11,350 kilograms).

Wingspan: 95 feet (29 meters).

Length: 64.5 feet (19.7 meters).

Height: 17 feet (5.2 meters).

York City and Los Angeles. Its flight times were 16 hours eastbound and 17 hours 45 minutes westbound.

Before the end of the year, United Airlines also had ordered the DC-3, which was proving cheaper to operate than the Boeing 247. Over the next 2 years, thirty airlines placed orders for the DC-3. By 1939, more than 90 percent

of Americans who bought an airline ticket flew on a DC-3.

Energy and power are measured in a variety of units. Units of energy used in the United States include the foot­pound, the Btu, and the kilowatt-hour. The foot-pound is the energy needed to lift a 1-pound weight a distance of 1 foot. The Btu, or British thermal unit, is the amount of heat needed to raise the temperature of one pound of water by one degree Fahrenheit. The kilowatt – hour is the amount of energy needed to supply one kilowatt of power for one hour (1 kilowatt equals 1,000 watts).

The international unit of energy is the joule-the amount of energy used, or work done, when a force of one newton acts through a distance of one meter. Another way to describe a joule is to say it is the energy needed to lift a small apple 3.28 feet (1 meter) off the ground.

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JOHN PRESCOTT JOULE (1818-1889)

The joule, the international unit for measuring energy, is named after English physicist John Prescott Joule. Joule studied heat and mechanical work (the work done in moving objects) and how they are connected.

His research led to the law of conser­vation of energy. Joule also found the link between the electric current flowing through something and the amount of heat given out. This con­nection is known as Joule’s Law, or the Joule Effect.

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Power is the amount of work done per second. It is a measurement of how fast energy changes from one form to another. The international unit of power is the watt. One watt is the same as one joule per second. A 100-watt light bulb changes 100 joules of electrical energy into light and heat every second. A large airliner’s engine is as powerful as about 2 million of these light bulbs, or about

200,0 kilowatts.

Power also can be measured in horsepower. One horsepower used to be
the power of an actual horse. Today, it is the same as about 746 watts or 550 foot-pounds per second. A big airliner engine produces approximately 270,000 horsepower—more power than one – quarter of a million horses!

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SEE ALSO:

• Bird • Force • Fuel • Gravity • Jet

and Jet Power • Laws of Motion

• Weight and Mass

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Building flying boats was a specialized business. One of the few companies making these aircraft was the German company Blohm und Voss. It built the biggest flying boat of World War II: the
six-engine BV 222 Viking, originally planned as a civilian aircraft. During the war, however, the Viking became a mil­itary transport, flying troops and sup­plies to German bases in North Africa. After Viking, Blohm und Voss built the even larger BV 238. This giant weighed as much as three B-17 bombers. It made its first flight in 1945 but was destroyed shortly afterward by Allied aircraft.

Even the giant BV-238 would have been dwarfed alongside the Hughes H4 Hercules. Built by U. S. millionaire and aviator Howard Hughes, this was the biggest flying boat ever. Also known as the Spruce Goose, it was piloted on its unsuccessful first and only flight by

Howard Hughes himself. The H4 flew for about 1 mile (1.6 kilometers) on November 2, 1947, but rose no higher than about 80 feet (24.4 meters). The H4 never flew again. Another postwar giant, the British Princess (1952), which had ten engines, also failed. It was clear that land planes, not flying boats, were the future for passenger flying.

The Martin Company, founded by U. S. aviation pioneer Glenn L. Martin

in 1917, produced several successful flying boats for the U. S. Navy, such as the PBM Mariner (1939) and P5M Marlin (1948). Martin also built the four-engine Mars, the biggest flying boat ever used by the U. S. Navy. Entering service in 1943, the Mars was able to carry a load of 20,500 pounds (9,307 kilograms) from California to Hawaii; it once carried 308 people. Martin’s P6M SeaMaster (1955) was jet-powered and probably

THE HUGHES H4 HERCULES (SPRUCE GOOSE)

The Hughes H4 was the biggest flying boat and the biggest propeller plane ever built. It weighed 180 tons (163 metric tons) and was 219 feet (67 meters) long. It had the biggest wingspan of any airplane-320 feet (98 meters). The H4 had eight engines and could have seated 700 passengers, but it was designed to be a military aircraft. The H4 is now on display at the Evergreen Aviation Museum in McMinnville, Oregon. The huge hangar in which the giant airplane was built later became a movie studio.

the fastest flying boat ever, with a speed of over 600 miles per hour (965 kilo­meters per hour). Only three were built before the U. S. Navy canceled the contract in 1959. The propeller-engine Marlin was the last flying boat to serve with the U. S. Navy, flying until 1966.

Trips to the ISS or to the Moon— and the far longer journey to Mars—still rely on conventional rocket launch and propulsion systems. Alternative systems will be needed for longer flights to explore deep space beyond the solar sys­tem. Scientists are investigating ion engines to replace chemical-fuel rockets
for long missions. An ion engine ejects positive ions (electrically charged parti­cles) to propel the spacecraft. It gives just a small thrust, but it is very effi­cient, needs little fuel, and can be made very light. Over many months, an ion – engine spacecraft could accelerate to very high speeds.

Another possibility is the solar-sailed spacecraft. A solar sail is a panel made from reflective materials; instead of catching the wind like a sailing ship, the solar sail is “blown along” by streams of light particles (photons) emitted from the Sun. A solar spacecraft would not need to carry onboard fuel. Although acceleration is slow to start with, it could eventually reach speeds of

200,0 miles per hour (322,000 kilome­ters per hour). Such a craft could travel
to the edge of the solar system in eight years, compared with the forty years taken by the Voyager 1 spacecraft.

GPS satellites last up to ten years, and new satellites are launched from time to time to replace older satellites. Each new generation of satellites is more advanced than the previous generation.

The first generation of GPS satellites was called Block I. These were experi­mental satellites used to test the system. Block II satellites formed the first opera­tional network. Block IIA satellites are a more advanced version of these. The next generation—Block IIR satellites— can be reprogrammed in space to fix

problems and upgrade their services.

The updating continues. Block IIR satellites are already being replaced with a new generation of satellites called Block IIR-M. Block IIF satellites are due for launch in 2009, and yet another new generation, Block III, is due for launch in 2012. Block III satellites will transmit more signals more powerfully on more frequencies. This will make it much easier to pick up GPS signals with less powerful receivers, and GPS equipment will shrink in size in the coming years. In the future, many portable products— from watches and personal music play­ers to cell phones and laptop comput – ers—may have built-in GPS receivers.

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Gossamer Penguin

Type: Experimental aircraft.

Manufacturer: AeroVironment, Inc.

First flight: April 7, 1980.

First solar-powered flight: May 18, 1980. Primary use: Research.

ossamer Penguin was the world’s first solar-powered airplane to carry a human pilot. It made its first flight in 1980. Gossamer Penguin is one of several experimental aircraft designed to investigate the possibility of using energy from the Sun, rather than fossil fuels, to power airplanes of the future. The advantage of a solar airplane is that it could fly for many days with­out ever having to land, because its power source (sunlight) is all around it in the atmosphere.

The inventor of Gossamer Penguin was Dr. Paul MacCready, a pioneer of alternative airplane technologies. In 1977, he built Gossamer Condor, a pedal-powered plane that won the Kremer Prize. This award had been offered since 1959 to any inventor who could build a human-powered airplane capable of flying a figure-8 course around two markers placed 0.5 miles (0.8 kilometers) apart, while staying at least 10 feet (3 meters) off the ground.

MacCready followed up his 1977 achievement in 1979 with Gossamer Albatross. This was the first human – powered airplane to fly across the English Channel between England and France. The pilot’s pedaling provided the energy to turn a propeller and proved that lightweight pedal-planes could fly considerable distances using very little energy. Duration of flight, however, depended on a human pilot who soon got tired.

The Sun, on the other hand, offers limitless energy, so inventors are very interested in solar-powered airplanes. The first solar-powered airplane was Sunrise II, a remote-controlled vehicle built by Robert Boucher in 1974.

Using the experience they had gained with Gossamer Albatross, MacCready and his team, advised by Boucher, built a version three-fourths the size, which was powered by an Asro-40 electric motor. The electric plane, Gossamer Penguin, took to the air in 1980. Like Gossamer Albatross, it was made of lightweight plastic, carbon fiber, poly­styrene, and sheet film. Power for the motor came either from twenty-eight batteries or from 3,920 solar cells, which could convert sunlight into electricity. The cells were mounted on the plane’s 71-foot-wide (22-meter-wide) wings.

The first flight, using battery power, took place on April 7, 1980, at Shafter Airport near Bakersfield, California. It was made by MacCready’s son (also named Paul), then age thirteen and weighing only 80 pounds (36 kilo­grams). The boy then made one short solar-powered flight on May 18.

More solar-powered flights were soon made in the Gossamer Penguin by pilot Janice Brown, who weighed in at around 100 pounds (45 kilograms).

О The solar – powered Gossamer Penguin is flown here by schoolteacher Janice Brown, a qualified pilot. The solar panel (top) is tilted toward the Sun.

On August 7, 1980, she flew the Penguin for about 2 miles (3 kilometers) in a flight lasting 14 minutes.

After the Gossamer Penguin, the MacCready team built Solar Challenger. This plane had smaller wings but an extra-large rear stabilizer. The stabilizer offered enough surface area for 16,128 solar cells, which meant the Solar Challenger was a lot more powerful than the Penguin. In 1981, the Solar Challenger became the first solar-pow­ered airplane to cross the English Channel, completing a trip of 161 miles (259 kilometers) from north of Paris, France, to Kent, England.

The success of Gossamer Penguin and Solar Challenger was followed up by
later solar airplanes, such as Pathfinder. This unmanned research airplane, devel­oped by NASA, first flew in 1993. Pathfinder and its successor, Pathfinder Plus, set several altitude records, reach­ing a height of over 80,000 feet (24,400 meters) in 1998.

Solar-powered flying wing airplanes, remotely controlled from the ground, may someday be able to fly for weeks or months and help carry out scientific research, mapping, and other tasks.

SEE ALSO:

• Aircraft, Experimental • Energy

• Fuel • Future of Aviation

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A twin-rotor helicopter has a long, wag­onlike body-for carrying passengers or

О A twin-rotor CH-47D Chinook carries a fork­lift as part of a recovery mission in Iraq in 2006.

cargo-and a large rotor at either end. One of the first “tandem rotor” heli­copters was the Piasecki PV-3 (1945), which was nicknamed the “flying banana.” The Piasecki PV-3 was able to carry ten people at 120 miles per hour (193 kilometers per hour).

The most famous example of a twin – rotor wagon helicopter is the CH-47 Chinook. In these large helicopters, the tail rotor rotates at a slightly higher level than the front rotor. The two rotors turn in opposite directions to prevent the helicopter from spinning around in the air. These big machines are less agile

THE CHINOOK

The Piasecki company pioneered the twin-rotor wagon helicopter with the "flying banana" of 1945. Piasecki later became Vertol (1956) and sub­sequently merged into Boeing. Its most famous helicopter is the CH-47 Chinook. First flown in 1961, the Chinook has a top speed of about 180 miles per hour (290 kilometers per hour) and a payload capacity of 14 tons (13 metric tons). The Chinook has seen action in combat zones around the world and is one of the most versatile and hard-working air­craft in history.

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than single-rotor helicopters, and pilots have to watch out that the long rotor blades do not smash into buildings or trees when flying low or landing. A vari­ation of the twin-rotor design is the coaxial-rotor helicopter, in which the two rotors are mounted one above the other.

new era in space exploration began on November 20, 1998, when the first module of the International Space Station (ISS) was launched into space. The space station is an orbital science laboratory and research facility, circling Earth at a height of 200-250 miles (320-400 kilo­meters). The ISS makes almost sixteen orbits every day-each orbit lasts 91.61 minutes. The space station’s average speed is 17,165 miles per hour (27,620 kilometers per hour). Since 2000, the ISS has been staffed by teams of astronauts.

The Space Station Concept

The term “space station” was first used in 1923 by German writer Hermann

Oberth, who foresaw a giant wheel in space from which astronauts might travel to the Moon and to the other planets. Rocket engineer Wernher von Braun described a similar concept in 1952. Orbital space stations have fea­tured in science fiction books and movies, such as 2001: A Space Odyssey. In many stories, a space station was a spaceport for rockets. These fictional space stations spun like mini-planets, with centrifugal force producing artifi­cial gravity so that the people inside did not float around.

The world’s first real space station, a much smaller structure, was launched in 1971. This was Salyut 1, launched by the Soviet Union. It was followed in 1973 by the first U. S. space station, Skylab,

which was visited by three crews of astronauts. The Soviets flew much longer missions than the Americans,

with some cosmonauts living in orbit for a year or more. In 1986 the Soviet Union

launched Mir, a space station big enough for six people.

In 1995 the U. S.

Space Shuttle Atlantis

docked with Mir, the

О In December 1998, the U. S. module Unity (left) was attached to the Russian module Zarya (right) in the first phase of construction of the ISS.

first time a U. S. spacecraft had linked up with the Russian space station. The modular design of Mir, with its solar panel “wings” and the docking unit used to link with the Shuttle, were forerunners of systems later developed for the International Space Station.