Promoting environmental sustainability in society through the mission of the university 139

Date: Born on November 5, 1917, in Challans, France;

died on February 12, 2000, in Paris, France Definition: Pioneer female test pilot and world speed

re-cord holder.

Significance: Beginning her aviation career as a stunt pi-lot, Auriol went on to fly more than one hundred dif-ferent types of planes as one of France’s most suc-cessful military test pilots of either gender. She held many world speed records throughout the 1950’s and was the second woman to break the sound barrier.

Jacqueline Auriol did not start flying until she was thirty years old, when she did so only out of curiosity. The daughter of a wealthy timber importer and shipbuilder, she studied drawing and painting at the École du Louvre and psychotherapy at the Sorbonne. In 1938, she married Paul Auriol, the son of future French president Vincent Auriol, and together they were active as part of the French Resis-tance during World War II. The couple had two sons, Jean-Paul and Jean-Claude.

Encouraged by her husband, Auriol first qualified as a tourist pilot in 1948 and later studied aerobatics with Raymond Guillaume, considered by many to be one of France’s greatest stunt pilots. As her interest grew, she re-alized she would need a military license if she wanted ac-cess to planes used by the Groupe de Liaisons Aériennes Ministérielles (GLAM), an elite group of military pilots.

Auriol’s life changed dramatically in 1949, when a sea-plane on which she was a passenger crashed into the River Seine, and she was severely injured. She underwent twenty-two operations to rebuild her face and did not permit her two children to see her for nearly two years because of her disfigurement. While in the United States for the final two operations, she earned her helicopter pilot’s license in only four weeks.

Auriol did not allow her injuries to prevent her from be-coming licensed as a military pilot in 1950. She was ac-cepted as a test pilot at the French Flight Test Center in Bretigny, France. In 1951, she reached a speed of 507 miles per hour in one of the first Vampire jets, breaking American aviator Jacqueline Cochran’s speed record. For this, the first speed record attained by a French pilot since World War II, she received the French Légion d’Honneur and the American Harmon Trophy.

Overall, Auriol held the women’s world speed record five times between 1951 and 1964. In 1953, she became the second woman to break the sound barrier and was one of the first pilots of either gender to pilot the Concorde.

Auriol later worked with the French Ministère de la Coopération, locating water and mapping crop species by using remote sensing techniques. For her agricultural work, Auriol received the Ceres Medal of the United Na-tions Food and Agriculture Organization.

P. S. Ramsey Bibliography

Auriol, Jacqueline. I Live To Fly. Translated by Pamela Swinglehurst. New York: Dutton, 1970. Jacqueline Auriol’s autobiography, describing her childhood, mar-riage, wartime activities, and her many aviation experi-ences.

Cadogan, Mary. Women with Wings: Female Flyers in Fact and Fiction. Chicago: Academy Chicago, 1992. Profiles a wide variety of women in aviation, from eighteenth century balloonists to twentieth century astronauts.

Welch, Rosanne. Encyclopedia of Women in Aviation and Space. Santa Barbara, Calif.: ABC-Clio, 1998. A refer-ence work containing a broad overview of the role played by women in the fields of aviation and space.

See also: Aerobatics; Concorde; Military flight; Sound barrier; Test pilots; Women and flight

Autopilot

Also known as: Automatic flight control systems or in-tegrated flight control systems

Definition: A device used to control an aircraft in flight automatically.

Significance: Autopilots are equipped on large com-mercial, military, and many small aircraft. By reduc-ing pilot workload, autopilots greatly increase flight safety.

Jacqueline Auriol Encyclopedia of Flight

Nature and Use

Many aircraft are equipped with autopilots that will fly an aircraft automatically while the pilot accomplishes other tasks. These systems vary greatly in sophistication, from simple wing levelers to completely integrated flight con-trol systems.

The simplest autopilot is a single-axis system. Most single-axis autopilots are designed to control the motion of the aircraft around the aircraft’s longitudinal axis, pass-ing from the front of the aircraft to the rear. When move-ment around the longitudinal axis becomes unstable, then the aircraft will roll, or tip, from side to side. In its simplest form, the single-axis autopilot may be referred to by pilots as a wing leveler. Upon activation, a wing leveler will stabilize the aircraft by leveling the wings. By adding features such as turn, heading, and navigational control, pilots can use a single-axis system throughout most of the flight.

Another common type of single-axis system is known as the yaw damper. This autopilot maintains control of the aircraft around the vertical axis, running through the air-craft from top to bottom. When movement around the ver-tical axis becomes unstable, the aircraft is considered to be slipping or skidding sideways. This motion is known as yaw. Yaw dampers are designed to prevent slipping and skidding.

A form of autopilot commonly used on medium-sized aircraft is the dual-axis system. A dual-axis autopilot will maintain control of the aircraft around both the lateral and the longitudinal axes. The lateral axis of an aircraft is an imaginary line passing from wingtip to wingtip. Move-ment around the lateral axis causes the front of the airplane to move up or down.

For example, a dual-axis autopilot will be able to keep both the wings and the nose of the aircraft level. Pilots may use the dual-axis system to hold a particular direction, fol-low commands from a navigation system, maintain an alti-tude, and climb or descend at a specified rate.

The three-axis autopilot is a combination of a dual-axis system and a yaw damper. Airliners and large business air-craft are normally equipped with a three-axis autopilot.

Three-axis systems are connected with navigation and flight-management systems. In addition, they may include features such as throttle control and ground steering.

Integration

Many autopilots can connect to, or be integrated with, a navigation system. In a single-axis autopilot, this may merely be a connection to the directional gyro. In a com-plex three-axis system, all of the navigation devices may

be connected to the autopilot. In this case, the autopilot could be considered an integrated flight control system.

Most integrated flight control systems include a special attitude indicator known as a flight director indicator. In addition to the symbolic airplane and horizon reference line found in most attitude indicators, a flight director indicator includes a special set of needles called flight di-rector, or command, bars. The flight director bars will move up, down, right, and left to indicate where the auto-pilot intends to fly. Often, these bars are operated by a special computer running in parallel with the autopilot computer. In case of an autopilot failure, the flight director computer will still be able to manipulate the flight director bars. Pilots can manually fly a precise flight path by keep-ing the bars centered. By allowkeep-ing the flight director com-puter to make the complex calculations involved in flying a precise flight path, pilots are still able to reduce their workload.

How the System Works

In order to control the aircraft, an autopilot must be able to sense attitude. To do this, autopilots rely on gyroscopic in-struments, or accelerometer-based sensors. Often, the atti-tude gyro is used to transmit information regarding pitch and roll attitude to the autopilot computer. A turn and bank indicator or a turn and slip indicator can be used to supply yaw information. The autopilot computer will compare the actual flight attitude of the aircraft with the desired flight attitude and, if necessary, move the appropriate control surface.

The device that operates the control surfaces of the air-craft is called a servo. A servo converts electrical energy into mechanical energy. Servos may be electric, hydraulic, or pneumatic. Electric and hydraulic servos are quite com-mon. Electric servos are widely used on aircraft with me-chanical or fly-by-wire controls, and hydraulic servos are widely used on aircraft with hydraulic controls.

Electric servos contain a small, electric motor. In this type of system, the computer sends a voltage to the servo, causing the motor to rotate. The motor is connected to the aircraft controls, and as the motor turns, the controls are moved.

Hydraulic servos contain a small, electrically con-trolled, hydraulic actuator. In this type of system, the com-puter sends a voltage to the actuator. Valves within the ac-tuator channel hydraulic fluid in and out of small cylinders containing pistons. The pistons are connected to the con-trol surface, and, as they move, the surface moves.

Pneumatic servos contain electrically operated valves.

These valves channel air into bellows that are connected to

Encyclopedia of Flight Autopilot

the aircraft controls. The inflation and deflation of the bel-lows causes the controls to move.

Thomas Inman Bibliography

Brown, Carl A. A History of Aviation. 2d ed. Daytona Beach, Florida: Embry-Riddle Aeronautical Univer-sity, 1980. A well-illustrated book that covers the his-tory of flight from ancient times to the space age.

Eismin, Thomas K. Aircraft Electricity and Electronics.

5th ed. Westerville, Ohio: Glencoe, 1994. A beginner’s text starting with the fundamentals of electricity and ending with electric instruments and autoflight sys-tems.

Helfrick, Albert. Principles of Avionics. Leesburg, Va.:

Avionics Communications, 2000. A very complete avi-onics text that includes history.

Jeppesen Sanderson. Instrument Rating Manual. 7th ed.

Englewood, Colo.: Jeppesen Sanderson, 1993. A text-book designed to assist pilots to prepare to add an in-strument rating to their pilot license.

See also: Airplanes; Avionics; Flight control systems; In-strumentation; Pilots and copilots; Roll and pitch

Avionics

Also known as: Aviation electronics

Definition: A combination of the words “aviation” and

“electronics.”

Significance: Many aircraft cannot fly without avion-ics. Avionic equipment includes a variety of systems designed to assist pilots, aviation maintenance tech-nicians, and passengers.

History

From the time avionics were invented in 1903 until ap-proximately 1930, pilots rarely used them, navigating in-stead by known landmarks on the ground. In the 1930’s, however, engineers began installing communications and navigation equipment in airplanes. The first system de-signed for airplane navigation was the direction finder (DF), also known as a homing beacon. In the late 1930’s, the government began installing the first range stations, which allowed pilots to follow a specific course. Before World War II (1939-1945), electronic equipment was large, heavy, and often required an extra person to operate; there-fore, only large aircraft used avionics.

During World War II, both Allied and Axis forces de-veloped radio detection and ranging, or radar. In addition, the Allies developed the identification, friend or foe (IFF) system. The IFF system became the air traffic control (ATC) transponder. Throughout the 1940’s, engineers made many improvements in the size and reliability of avionics.

During the late 1940’s and early 1950’s, the very high fre-quency omnidirectional range beacon was developed, which was a great improvement to the original range sta-tions.

In the 1960’s, radios became lighter and smaller, mostly due to the application of the transistor to avionic equipment. The first avionics to use transistors were hy-brids, or radios containing both vacuum tubes and transis-tors. In the 1970’s, manufacturers introduced the first reli-able solid-state avionics, using semiconductor devices rather than electron tubes. Simultaneously, avionics using digital systems were introduced. These developments al-lowed for even smaller, lighter, and easier to use systems.

Consequently, small personal aircraft of the 1970’s were able to have more complex avionics than could the large airliners of the 1950’s.

The introduction of the microprocessor and database technology in the 1980’s created a revolution in the avion-ics industry. For the first time, pilots could use long-range navigation systems, such as loran-C and Omega, for air-craft navigation. This new technology also allowed for in-creasingly smaller, lighter, and even easier to use avionics.

The 1990’s brought the introduction of satellite naviga-tion, known as the Global Positioning System (GPS). By the end of the decade, the U.S. government decommis-sioned the Omega navigation system, which GPS had made obsolete.

In the early twenty-first century, improvements in mi-croprocessors allowed many more improvements in avi-onics systems. Three-dimensional moving map displays and low-cost electronic flight instrumentation are a few of the improvements to come about in the first decade of the third millennium.

Navigation

Avionics assist the pilot to navigate the aircraft in several ways. Many different navigation systems help pilots find their way across the globe and locate runways.

The automatic direction finder (ADF) indicates the direction of special radio navigation stations and AM broadcast stations. This system receives radio signals in the low- and medium-frequency bands. An indicator in the instrument panel simply points toward the source of the ra-dio signals.

Avionics Encyclopedia of Flight

The very high frequency omnidirectional range beacon system provides the pilot with directional information rel-ative to a course. This system receives radio signals in the very high frequency range from a station on the ground.

The system is made up of a radio receiver connected to a device that converts the radio signal to visual information.

The pilot chooses a bearing to fly, and a special indicator in the panel shows whether the airplane is to the left or right of a course, also known as a radial, that passes through the navigation station.

Loran-C provides pilots with long-range area naviga-tion. The name “loran-C” is an abbreviation of “long-range navigation,” with the “C” representing the fact that the current system is the third generation of loran. Ori-ginally, loran-C worked as a maritime navigation system;

however, with microprocessor and database technology, it became available to pilots. Loran-C does not require the pilot to use a navigation station as a reference point, as do the very high frequency omnidirectional range beacon and the automatic direction finder. Instead, the pilot sim-ply chooses an origin and destination within the loran-C coverage area, and the loran-C guides the pilot directly from the origin to the destination. The system consists of a low-frequency receiver, computer, database, and an indi-cator. The receiver listens for pulses from a set of transmit-ting stations, and the computer measures the time delay between pulses to determine position.

The Global Positioning System (GPS) provides pilots with a worldwide area navigation system. Although GPS is similar in design to the loran-C, it is much more accu-rate. Twenty-four GPS satellites orbit the earth and pro-vide pilots with three-dimensional navigation signals. Of-ten, the GPS system will work with a moving map display to show exactly where the airplane is. The system consists of an ultrahigh frequency receiver, computer, database, and indicator. The receiver listens for pulses from the sat-ellites, and the computer measures the time delay between pulses to determine position. With wide- and local-area augmentation systems, GPS can be used as the sole means of navigation.

The Instrument Landing System (ILS) gives pilots guidance toward runways and consists of three major com-ponents. The first, the aircraft’s localizer transmitter, is in-tegrated with the VHF omnirange. When the pilot selects a special ILS channel, the VHF omnirange system switches to localizer mode. Now, instead of having several courses to choose from, the pilot has only one, which will lead to the end of the runway. The course directing indicator (CDI) will indicate whether the course is to the pilot’s left or right.

The second ILS component, the glide slope, provides pilots with vertical guidance to the end of the runway. The glide slope consists of a UHF receiver and circuitry that converts navigation signal information to visual informa-tion. When the pilot selects an ILS channel with the VHF omnirange system, the glide slope automatically becomes active and provides information on the CDI to indicate whether the pilot is above or below the proper glide path.

The final ILS component, the marker beacon, then turns on a light in the cockpit as the aircraft passes over certain checkpoints during the approach to the airport. A special receiver in the airplane is tuned to 75 megahertz and will listen for special signals from marker transmitters placed along the localizer course.

Distance measuring equipment (DME) uses radar prin-ciples to measure the distance between the aircraft and special navigation stations on the ground. The DME dis-plays distance, speed, and time to or from the navigation station. The aircraft system consists of a transmitter and a receiver. The UHF transmitter sends pairs of pulses to a ground station, which the ground station then sends back to the aircraft. The DME will measure the time elapsed from when the pulses were sent to when they return and will calculate distance, speed, and time.

Communication

There are many communications systems on board air-craft. In small airplanes and helicopters, the system will consist of a VHF transceiver for the pilot to communicate with air traffic controllers. Similar to a citizen’s band ra-dio, this more powerful system can have up to 2,280 chan-nels. Many aircraft also have an intercom with which to communicate with other crewmembers and passengers.

In addition to the VHF transceiver and intercom, some aircraft may have high-frequency transceivers or satellite transceivers to allow long distance communication on transcontinental flights. Although similar in purpose, the design of these two systems is quite different. The high-frequency (HF) transceiver transmits and receives fre-quencies between 3 and 30 megahertz. Radio frefre-quencies within this range have the ability to stay in the earth’s at-mosphere and travel around the world. The satellite system uses ultrahigh frequencies and an antenna that swivels to remain pointed at a communications satellite in orbit above the earth. The signal travels from the airplane to the satellite and is then relayed to any place on Earth.

Another communications system is the aircraft com-munications and reporting system (ACARS), a private, low-speed, digital communications system used by the air-lines to communicate between the aircraft and the

opera-Encyclopedia of Flight Avionics

tions center. Aircraft may also include passenger address systems that allow the pilots to speak to passengers and a radio telephone system that allows passengers to call friends, relatives, and business associates.

Surveillance

Air traffic controllers use two systems to track the move-ments of aircraft: the primary surveillance radar and the secondary surveillance radar. The primary surveillance ra-dar uses a powerful transmitter and a large rotating an-tenna to send strong bursts of microwave energy into the

Air traffic controllers use two systems to track the move-ments of aircraft: the primary surveillance radar and the secondary surveillance radar. The primary surveillance ra-dar uses a powerful transmitter and a large rotating an-tenna to send strong bursts of microwave energy into the