Category FLIGHT and M ОТІOIM

Aeronautical research has pro­gressed amazingly fast. Only seventy-three years after the Wright brothers’ historic first powered flight, Concorde passengers were relaxing in air-conditioned luxury, flying at twice the speed of sound nearly 11 miles (18 kilometers) above Earth.

There are now military air­craft that can fly without a pilot. Some of them are flown by a pilot in a cockpit on the ground, linked to the aircraft by radio. The latest unmanned air vehicles (UAVs), or drones, are able to fly themselves and carry out missions on their own without a person in control.

Aeronautical research con­tinues in all developed countries today. The National Aeronautics and Space Administration (NASA) is known as the agency that oversees U. S. space explo­ration, but it is also a world leader in aeronautical design. Large aircraft manu­facturers and universities also carry out research in all aspects of aeronautics and aeronautical engineering.

The advantage of an air-cushion vehicle over conventional craft is that it can travel over water faster than most ships.

О u. s. Marines load a Humvee onto a Landing Craft Air Cushioned (LCAC) during a 2006 exercise in North Carolina. Two huge propellers are visible at the rear. The skirt will inflate with a cushion of air supplied by four fans when the craft leaves the shore.

Amphibious ACVs have the added advantage of being able to travel over­land, too, and they can do so faster than most trucks or military vehicles. Amphibious ACVs can cross deserts, swamps, lakes, or ice with equal ease.

At first, ACVs seemed to offer enor­mous potential for public transportation and military use. Problems in their use reduced their commercial value, how­ever. The airscrews were too noisy for ACVs to move around cities. At sea, ACVs traveling fast over the ocean put out a lot of spray, and the salt spray damaged the gas turbine engines. The engines also used a lot of fuel, making ACVs expensive to operate. While com­fortable for passengers in calm water, even big ACVs could not cope well with rough seas. These disadvantages caused the early optimism about them to fade.

The military in Britain and the United States experimented with ACVs as amphibious assault and patrol craft. The U. S. Marine Corps and U. S. Navy use an ACV designed in the 1980s as a landing craft (a vessel used for taking troops and equipment to shore). The Landing Craft Air Cushioned (LCAC) is carried inside a large naval ship. Offloaded from the ship, the LCAC can move inshore and up a beach to land troops and supplies. The LCAC has four engines (two for propulsion, two for lift) and four fans; its top speed is about 45 miles per hour (72 kilometers per hour).

While some ACVs are used in public and private transportation, the ACV has not yet developed into the widespread system that its inventors expected. The air-cushion principle has been tried in other forms, however. High-speed hovertrains have been tested for railroad use. Enthusiasts and model makers enjoy building small ACVs as a hobby.

RAM WINGS

An interesting vehicle that uses the ground-effect principle, rather like flying boats did in the 1920s, is the ram-winged craft. It looks like an airplane, but it never takes off. Instead of flying, it skims over the surface. The Japanese and the Russians have built ram-winged machines, which are good at travel­ing over lakes and icy terrain.

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SEE ALSO:

• Aircraft, Military • Flying Boat and Seaplane • Lift and Drag • Pressure

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The 1940s and 1950s were decades of more experimentation, as designers tried out new wing shapes and jet engines. The 1947 Northrop YB-49 had no fuse­lage or tail plane. It was just a curved wing, with engines, fuel tanks, and crew compartment inside the flying wing. This airplane looked so unusual that some people claimed they had spotted a

PIGGYBACK PLANES

Several designers experimented with the idea of one aircraft carrying another. In the 1930s, engineers tried out the idea with a small seaplane fixed on top of a flying boat. The fly­ing boat took off before releasing its passenger craft to fly on alone. The idea was to extend the seaplane’s range for mail flights by saving fuel on takeoff. A similar idea was tried in 1948 by the U. S. Air Force. A tiny "parasite" fighter was hooked to the underside of a bomber. The McDonnell XF-85 Goblin fighter managed the risky maneuvers of launching and rehooking onto the bomber several times before the project was canceled. NASA revived the piggyback idea in the 1970s for ferrying Space Shuttles across the country on the back of a Boeing 747.

UFO or flying saucer. The Northrop designers also tested a smaller flying wing, the XP-79B. It was supposed to destroy enemy bombers by slicing through their tails. It flew once, for 15 minutes, in 1945; the pilot reported it was uncontrollable.

Other oddities included Convair’s F2- Y1 Sea Dart (1953), the only jet fighter with water skis, which enabled it to take off and land on water. Unfortunately, it needed almost a mile of water to take off. Hiller’s Pawnee of 1955—officially named the Experimental Ducted Fan Observation Platform—looked like a table lifted by air jets. A soldier could ride on top of it and fly around the battlefield. It never caught on.

Much experimenting went into mak­ing planes that would not need long runways at airfields. In 1954 Convair tested the turbo-prop XFY-1, which was nicknamed “Pogo.” This plane rested on its tail, facing straight up, for takeoff. The tail-sitting design was tried again in the Ryan X-13 Vertijet of 1955. The British went for a more conventional, horizontal position in the Short SC-1
and Hawker P-1127. These experiments in the 1960s led to the production of the Harrier V/STOL (vertical/short takeoff and landing) jet fighter.

Another strange shape was the 1980s Sikorsky X-Wing. This took off like a helicopter, but its X-shaped rotors func­tioned as fixed wings, making the X – Wing capable of faster forward flight.

ll large cities and many smaller ones have an airport, a place where passenger and cargo air­craft can land and take off. Airports are important transportation hubs. Civil air­ports are run as businesses, although they are often owned by governments, especially the larger facilities. There are also military airfields, which function as airports for armies, navies, and air forces.

Types of Airports

In the United States, the Federal Aviation Administration (FAA) classifies airports into two main categories: com­mercial service and general aviation. A commercial service airport handles air­liners on all routes: short commuter
trips, internal regional flights, national flights across the United States, and international flights to and from other countries. Commercial service airports also operate as cargo airports, where air­freight comes in and out.

A commercial service airport per­forms two main functions. First, it must make sure that airplanes land and take off safely. Second, it needs to handle passengers and cargo smoothly and rap­idly. Airports have facilities to process passengers and baggage through ticket­ing, check-in, security, and departure and landing procedures. They also have areas for freight handling and storage.

General aviation airports have either no scheduled passenger flights or small numbers of them. They handle all other kinds of airplanes-business, charter, and privately owned-except military flights. (Military airplanes usually use their own airfields.) A small general avi­ation airport handles light aircraft, such as single-engine private planes, while a larger one can also manage executive jets. General transportation airports, the biggest kind of general aviation airport, can handle a large airliner.

Most large U. S. airports are owned by city, county, or state governments or public corporations. Small airports are often privately owned. While most large airports are miles away from downtown, small airports in city centers can handle

V/STOL (short for vertical/short takeoff and landing) airplanes and helicopters. A landing area built specially for heli­copters is sometimes called a heliport.

ltitude means the height above a certain surface or level. Air temperature and air pressure fall with increasing altitude. In aviation especially, altitude is measured from the ground at sea level.

Why Altitude Is Important

Altitude is important in aviation for sev­eral reasons. Aircraft need to fly at a minimum altitude that enables them to safely clear obstacles on the ground. Every aircraft also has a “flight ceiling,” or maximum altitude at which it may fly. This ceiling is determined by the
aircraft’s capabilities and by whether or not it has a pressurized cabin.

Large airliners, such as the Boeing 747 jumbo jet, cruise at altitudes from about 28,000 feet (8,530 meters) to

41,0 feet (12,500 meters). The big jets fly at standard altitudes called flight levels. The last two zeroes of a flight level are usually left out, so an altitude of 37,000 feet (11,280 meters) is known as Flight Level 370 to a pilot.

An important reason to measure alti­tude is to avoid collision with another aircraft. Aircraft must maintain vertical distance from each other to prevent accidents when they are flying in the same area. For airplanes traveling below

29.0 feet (8,840 meters), the standard vertical separation is 1,000 feet (305 meters). Aircraft above 29,000 feet (8,840 meters) maintain a vertical dis­tance of either 1,000 feet (305 meters) or

2.0 feet (610 meters).

To stay safe from collision, it is essential that all pilots are measuring altitude compared to the same level. Otherwise, two planes flying at the same altitude-but one flying over a hill while the other is over lower ground-would register different altitudes but, in reality, be in danger of colliding. To avoid this, aircraft in flight measure their altitude compared to a reference point called mean sea level (MSL). Charts and maps used by pilots show the heights of mountains and high ground as heights above mean sea level.

An autogiro is a type of aircraft that looks like a helicopter but works in a different way. Autogiros are rotorcraft, or rotary wing craft. Like a helicopter, an autogiro has a rotor (a set of long thin blades) on top. Unlike a helicopter, an autogiro’s rotor is not powered by an engine-it freewheels, or autorotates. An autogiro is moved forward by an engine-driven propeller, like an airplane.

Just before an autogiro takes off, the pilot starts the overhead rotor spinning. The simplest way to do this is for the
pilot to reach up, take hold of one of the rotor blades, and push it around. Some autogiros use their engine to start the rotor spinning, and then the engine is disconnected from the rotor to let it spin freely on its own.

As the autogiro moves forward, the pressure of air pushing up against the bottom of the blades makes the rotor spin faster. As the blades spin, they gen­erate lift. They quickly generate enough lift for the craft to take off. An autogiro can take off in a much shorter distance than a fixed-wing plane.

In the same way as a helicopter, an autogiro is steered by tilting the rotor.

When the whole rotor tilts, its down – wash (or the air blown downward by the rotor) is tilted to the front, back, or one side. This action pushes the autogiro in the opposite direction. A rudder at the back turns the craft’s nose to the left or right.

A rudder works by deflecting air to one side, so it needs a fast flow of air blowing across it to work. When an autogiro flies slowly, the air flows around it too slowly for the rudder to work well. A modern autogiro’s rudder, therefore, is placed behind its rear – mounted propeller. In this position, it gains a fast airflow from the propeller.

An autogiro has the same basic flight controls as a fixed-wing plane, but autogiros are much more maneuverable. A control stick steers the aircraft. Moving the stick to the front, back, or side moves the craft in that direction by tilting the rotor. Pedals operate the rud­der, and a throttle control adjusts the engine speed.

Spanish engineer Juan de la Cierva invented the autogiro in 1923. The first autogiros had short wings with ailerons for steering. In 1932 the wings were dis­carded, and a tilting rotor was used for steering instead. During the 1930s the development of helicopters overtook autogiros. Interest in commercial and military autogiros died away. A few autogiros were towed behind ships and submarines during World War II to act as spotter craft. They were used to look for enemy ships or submarine periscopes breaking the water’s surface.

AUTOGIRO TIME LINE

The Bell X-1 was basically a rocket engine with wings. The engine burned all its fuel in 2.5 minutes, and the X-1 certainly did not have enough fuel to take off under its own power-it would hitch a ride into the air beneath a B-29 Superfortress bomber. The bomber would climb to 25,000 feet (7,620 meters) before releasing the X-1.

The first flights of the X-1, which took place in Florida in early 1946, were unpowered. The X-1 then began to make powered flights from Muroc Army Air Field in California’s Mojave Desert. (The field was later renamed Edwards Air Force Base.) The rocket engine was tested for the first time by pilot Chalmers Goodlin, who made many successful test flights in the X-1. On the powered flights, the pilot ignited the rocket engine for a brief but very fast flight. When the engine cut out, the air­plane glided down, landing without engine power-a maneuver later used by the Space Shuttle.

At the time the fastest aircraft in the world was the British Gloster Meteor,

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CHARLES ELWOOD "CHUCK" YEAGER (BORN 1923)

Charles Elwood Yeager, always known as Chuck, was born in West Virginia. He flew as a fighter pilot in Europe during World War II, destroying thirteen enemy aircraft before being shot down over enemy territory in Europe. He managed to escape capture and make his way to England. After the war, Yeager became a flying instructor and test pilot, and he volunteered to fly the X-1. Between 1954 and 1962, he left test flying for other U. S. Air Force duties before returning to Edwards Air Force Base to head the Aerospace Research Pilot School. Yeager continued to fly fast airplanes. He had a nar­row escape in the 1960s when his NF-104 jet went into a spin and fell from a very high altitude. Yeager managed to eject and, although injured, parachuted down to land in the desert. In 1968 Yeager took command of a fighter wing. He retired in 1975.

which set a world speed record of 615 miles per hour (990 kilometers per hour) in September 1946. In August 1947 the Douglas Skystreak topped that with 650 miles per hour (1,046 kilome­ters per hour). No aircraft had yet flown supersonic in level flight.

black box is a recording machine carried by commercial and military aircraft and aboard the Space Shuttle. Designed to survive a crash, it is used to find out how an acci­dent occurred. Airplane crashes are very rare, but when a fatal accident does happen, it is important to find the cause. Knowing why one aircraft crashed may help to prevent other accidents.

After an accident, a team of investi­gators search through the wreckage, looking for clues. They also look for the piece of equipment referred to as the

THE FIRST BLACK BOX

The development of the black box flight recorder began in Australia in the 1950s. There had been a series of air crashes with no witnesses and no survivors. It was very difficult to find out what caused them. Dr. David Warren at the Aeronautical Research Laboratories of Australia wondered if a plane could be fitted with a recorder to give investigators infor­mation about a crash. His work resulted in the first flight data recorder in 1958. The first black boxes used magnetic tape to record and store information-today’s flight recorders use computer chips.

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black box. In fact, black boxes are not black-they are bright orange-and there are usually two of them.

The flight data recorder, one of the two black boxes, is the size of a large shoebox. To survive a crash, the box is made to withstand a force of 3,400 times the force of gravity for 6.5 milliseconds. (A millisecond is one-thousandth of a second.) It also withstands fire and being submerged in liquid.

The flight data recorder records hun­dreds of pieces of information about an aircraft. The data includes the aircraft’s speed, height, and direction. The device also records the positions of controls, the positions of the rudder and other control surfaces, and the engine speed.

The other black box is the cockpit voice recorder. It records sounds picked up by microphones in the cockpit. The pilots’ voices are recorded on one micro­phone. Another microphone in the cock­pit roof records the sounds of alarms, clicks of switches, and other background noises. At any moment, the box has retained the last thirty minutes to two hours of sound as a recording that can be retrieved if a plane crashes.

The information from both boxes is stored in computer chips. The chips are inside an extremely tough package called the crash survivable memory unit. The unit’s case is made of stainless steel or titanium. It is lined with fireproof insulation. To test the case’s toughness, the unit is fired out of a cannon and burned in a fire at 2000°F (1093°C) for an hour.

Some versions of the black box contain the flight data recorder and voice recorder in one unit. Whether they are combined

or separate, black boxes are usually installed in the plane’s tail, where they are most likely to survive. They may be thrown out of a plane by the impact of a crash, so they are designed to be easy to find. Apart from their bright color, they are fitted with a locator beacon that switches on automatically if the recorder lands in water. It emits an ultrasound pulse every second for a month. Divers or underwater craft can use the signal to locate the recorder. When a black box is found, the information in its memory can be downloaded and studied.

In the United States, black boxes are taken to the National Transportation Safety Board for expert analysis. Investigators include safety officials and representatives of the aircraft manufac­turer and operating airline. Together, these people try to piece together what happened in the last moments of a flight. Recorded conversations between
pilots can give clues, even if the pilots themselves did not know the cause of their problem. The flight data recorder offers minute detail of what the airplane was doing at any given second.

Cape Canaveral has a long association with aviation and spaceflight. During World War II (1939-1945), the U. S. Navy trained pilots there. After the war, the U. S. Army, U. S. Navy, and U. S. Air Force all used Cape Canaveral as a range for testing missiles.

In 1950 the U. S. Air Force took over the test range and set up the Cape Canaveral Air Force Station. It built a row of launch pads along the coast. The first rocket launch from Cape Canaveral took place at 9:28 a. m. on July 24, 1950. The rocket, named Bumper 8, was a modified World War II V-2 rocket.

The first launch control center was very basic. It was a small wooden shack about 450 feet (137 meters) from one of the launch pads. The launch center was buffered only

О Bumper 8 was the first mis­sile launched at Cape Canaveral. The launch, shown here, took place on July 24, 1950.

by a mound of dirt and sandbags, which would have offered little protection if a rocket had exploded on the pad. Later, a tank was used as a firing room to launch rockets.

There was so little housing at Cape Canaveral in the 1950s that most workers were obliged to live in tents. They had to deal with the local wildlife, which included mos­quitoes, alligators, and rattlesnakes.

Today, NASA has a fleet of satellites for communicating with Earth-orbiting satellites and manned spacecraft. This network of satellites is called the

Tracking and Data Relay Satellite System (TDRSS). When a ground station wants to send a signal to a spacecraft, it sends the signal up to the nearest TDRSS. The signal is then passed on from satel­lite to satellite around the world until it reaches a satellite in contact with the spacecraft. The TDRSS provides communication with many spacecraft, including the Space Shuttle, the International Space Station, and the Hubble Space Telescope.

TDRSS satellites orbit Earth 22,250 miles (35,800 kilometers) above the equator. This is a special orbit called geostationary orbit. A satellite in this orbit goes around the world once every 24 hours. As the Earth also spins once every 24 hours, this means that the satellite always stays above the same spot on Earth. As well as the TDRSS,

there are many other communications satel­lites using this orbit.

The radio signals sent to and from space­craft carry all sorts of information, including the voices of astronauts and mission con­trollers, video images from the Space Shuttle and International Space Station, command signals for controlling the movements of satellites, and science data from weather satellites and space tele­scopes. Engineering data also are sent automatically from rockets and spacecraft during missions so that mission controllers can monitor them. This form of com­munication is called telemetry.