Showing posts with label attitude indicator. Show all posts
Showing posts with label attitude indicator. Show all posts
Wednesday, September 9, 2009
Wednesday, September 10, 2008
Attitude indicator
From Wikipedia, the free encyclopedia
Attitude indicator (with integrated localizer and glideslope indicators) 
Drawing
An attitude indicator (ADI), also known as gyro horizon or artificial horizon, is an instrument used in an aircraft to inform the pilot of the orientation of the aircraft relative to earth. It indicates pitch (fore and aft tilt) and bank (side to side tilt), and is a primary instrument for flight in instrument meteorological conditions. Attitude indicators also have significant application under visual flight rules, though some light aircraft do not have them installed.
Attitude indicators use a gyroscope to establish an inertial platform. The gyroscope is geared to a display that has two dimensions of freedom, simultaneously displaying pitch and bank. The display may be colored to indicate the horizon as the division between the two colored segments (typically blue for sky and brown for ground), and is intended to be intuitive to use. The actual bank angle is calibrated around the circumference of the instrument. The pitch angle is indicated by a series of calibration lines, each representing 5° or 10° of pitch.
Most Russian-built aircraft have a somewhat different design. The background display is colored as in a Western instrument, but moves up and down only to indicate pitch. A symbol representing the aircraft (which is fixed in a Western instrument) rolls left or right to indicate bank angle.
The pitch angle is relative to the ground, which is not as helpful as knowing the angle of attack of the wing, a much more critical measure of performance. The pilot must infer the total performance by using other instruments such as the airspeed indicator, altimeter, vertical speed indicator, and power instruments, e.g. an engine tachometer. "Performance = Attitude + Power".
Some attitude indicators can only tolerate a specific range of bank angles. If the aircraft rolls too steeply — while performing aerobatics, for example — the attitude indicator can "tumble" and become temporarily unusable. For this reason, some attitude indicators are fitted with a "cage" (a device to restore the gyroscope to an erect position). Most modern attitude indicators slowly re-erect back to level after a tumble. Others do not tumble at all.
On the attitude indicator are two white or yellow horizontal lines with a dot between them. The horizontal lines of this symbolic aircraft represent the wings and the dot represents its nose. If the symbolic aircraft dot is above the horizon line (more blue background) the aircraft is nose up. If the symbolic aircraft dot is below the horizon line (more brown background) the aircraft is nose down. When the dot and wings are on the horizon line, the aircraft is in level flight.
Individual mechanical gyros are slowly being replaced by Attitude and Heading Reference Systems (AHRS), which use solid-state or miniature gyroscopes (MEMS gyroscope) to supply aircraft orientation information, supplemented by magnetometers to supply heading information. Historically, heading information was supplied by a separate gyroscopic instrument known as a directional gyro (DG, or heading indicator). AHRS are able to provide three-axis information that can be shared with multiple devices in the aircraft, such as "glass cockpit" primary flight displays (PFDs). AHRS have been proven to be highly reliable and are in wide use in commercial and business aircraft. Recent advances in MEMS manufacturing have brought the price of FAA-certified AHRS down to less than $15,000, making them practical for general aviation aircraft. If an aircraft's ADIs have failed there is a standby ADI located in the center of the instrument panel, where other standby basic instruments such as the airspeed indicator and the attitude indicator are also available. These mostly mechanical standby instruments are available even if the electronic flight instruments fail.
External Links
- [Crossbow Technology ] :Air Data Sensors, Primary Flight Display Systems
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Wednesday, July 16, 2008
Flight instruments
From Wikipedia, the free encyclopedia
Six basic instruments in a light twin-engine airplane arranged in the basic-T. From top left: airspeed indicator, attitude indicator, altimeter, turn coordinator, heading indicator, and vertical speed indicator
Most aircraft are equipped with a standard set of flight instruments which give the pilot information about the aircraft's attitude, airspeed, and altitude.
Most aircraft have these six basic flight instruments:
Altimeter
Gives the aircraft's height (usually in feet or meters) above some reference level (usually sea-level) by measuring the local air pressure. It is adjustable for local barometric pressure (referenced to sea level) which must be set correctly to obtain accurate altitude readings.
Attitude indicator (also known as an artificial horizon)
Shows the aircraft's attitude relative to the horizon. From this the pilot can tell whether the wings are level and if the aircraft nose is pointing above or below the horizon. This is a primary instrument for instrument flight and is also useful in conditions of poor visibility. Pilots are trained to use other instruments in combination should this instrument or its power fail.
The flight instruments of a Slingsby T-67 Firefly two-seat light airplane. The basic T is present on the left side primary pilot station
Airspeed indicator
Shows the aircraft's speed (usually in knots) relative to the surrounding air. It works by measuring the ram-air pressure in the aircraft's pitot tube. The indicated airspeed must be corrected for air density (which varies with altitude, temperature and humidity) in order to obtain the true airspeed, and for wind conditions in order to obtain the speed over the ground.
Magnetic compass
Shows the aircraft's heading relative to magnetic north. While reliable in steady level flight it can give confusing indications when turning, climbing, descending, or accelerating due to the inclination of the earth's magnetic field. For this reason, the heading indicator is also used for aircraft operation. For purposes of navigation it may be necessary to correct the direction indicated (which points to a magnetic pole) in order to obtain direction of true north or south (which points to the earth's axis of rotation).
Schempp-Hirth Janus-C glider Instrument panel equipped for "cloud flying". The turn and bank indicator is top center. The heading indicator is replaced by a GPS-driven computer with wind and glide data, driving two electronic variometer displays to the right.
Heading indicator
Also known as the directional gyro, or DG. Sometimes also called the gyrocompass, though usually not in aviation applications. Displays the aircraft's heading with respect to magnetic north. Principle of operation is a spinning gyroscope, and is therefore subject to drift errors (called precession) which must be periodically corrected by calibrating the instrument to the magnetic compass. In many advanced aircraft (including almost all jet aircraft), the heading indicator is replaced by a Horizontal Situation Indicator (HSI) which provides the same heading information, but also assists with navigation.
Turn and bank indicator, turn coordinator or turn indicator
The turn and bank indicator, also called the turn and slip indicator, displays direction of turn and rate of turn. Internally mounted inclinometer displays 'quality' of turn, i.e. whether the turn is correctly coordinated, as opposed to an uncoordinated turn, wherein the aircraft would be in either a slip or a skid. Replaced in the late sixties and early seventies by the newer turn coordinator, the turn and bank is typically only seen in aircraft manufactured prior to that time, or in Gliders manufactured in Europe.
A turn coordinator displays rate and direction of roll while the aircraft is rolling; displays rate and direction of turn while the aircraft is not rolling. Internally mounted inclinometer also displays quality of turn. Replaced the older turn and bank indicator.
Vertical speed indicator
Also sometimes called a variometer. Senses changing air pressure, and displays that information to the pilot as a rate of climb or descent in feet per minute, meters per second or knots.
Arrangement in instrument panel
Most aircraft built since about 1953 have four of the flight instruments located in a standardized pattern called the T arrangement. The attitude indicator is in the top center, airspeed to the left, altitude to the right and heading indicator under the attitude indicator. The other two, turn-coordinator and vertical-speed, are usually found under the airspeed and altitude, but are given more latitude in placement. The magnetic compass will be above the instrument panel, often on the windscreen centerpost. In newer aircraft with glass cockpit instruments the layout of the displays conform to the basic T arrangement.
See also
Glass cockpit
[edit] External links
Instrument Flying Handbook (FAA-H-8083-15A) 2007
The Gyro Horizon Enables Instrument Flying A history of how aircraft instrumentation was developed with an emphasis on the gyro horizon. (c) 2007
v • d • eFlight instruments
Pitot-static instruments: Altimeter · Airspeed indicator · Machmeter · Variometer
Gyroscopic instruments: Attitude indicator · Heading indicator · Horizontal situation indicator · Turn and bank indicator · Turn coordinator · Turn indicator
Navigation: Horizontal situation indicator · Course Deviation Indicator · Inertial navigation system · GPS · SIGI ·
v • d • eSatellite navigation systems
Historical
Transit (USA)
Operational
GLONASS (USSR/Russia) · GPS (USA) · Beidou (China)
Developmental
COMPASS (China) · Galileo (Europe) · IRNSS (India) · QZSS (Japan)
GNSS augmentation systems
EGNOS · GAGAN · GPS·C · LAAS · MSAS · WAAS · StarFire
Related topics
GNSS · GNSS reflectometry · Kalman filter
Other: Magnetic compass · Yaw string · Glass cockpit · EFIS
Retrieved from "http://en.wikipedia.org/wiki/Flight_instruments"
Categories: Aircraft instruments Aviation Display technology Measuring instruments Navigation Navigational equipment
This page was last modified on 1 July 2008, at 00:31.
All text is available under the terms of the GNU Free Documentation License. (See Copyrights for details.) Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a U.S. registered 501(c)(3) tax-deductible nonprofit charity.
Privacy policy
About Wikipedia
Disclaimers
Six basic instruments in a light twin-engine airplane arranged in the basic-T. From top left: airspeed indicator, attitude indicator, altimeter, turn coordinator, heading indicator, and vertical speed indicator
Most aircraft are equipped with a standard set of flight instruments which give the pilot information about the aircraft's attitude, airspeed, and altitude.
Most aircraft have these six basic flight instruments:
Altimeter
Gives the aircraft's height (usually in feet or meters) above some reference level (usually sea-level) by measuring the local air pressure. It is adjustable for local barometric pressure (referenced to sea level) which must be set correctly to obtain accurate altitude readings.
Attitude indicator (also known as an artificial horizon)
Shows the aircraft's attitude relative to the horizon. From this the pilot can tell whether the wings are level and if the aircraft nose is pointing above or below the horizon. This is a primary instrument for instrument flight and is also useful in conditions of poor visibility. Pilots are trained to use other instruments in combination should this instrument or its power fail.
The flight instruments of a Slingsby T-67 Firefly two-seat light airplane. The basic T is present on the left side primary pilot station
Airspeed indicator
Shows the aircraft's speed (usually in knots) relative to the surrounding air. It works by measuring the ram-air pressure in the aircraft's pitot tube. The indicated airspeed must be corrected for air density (which varies with altitude, temperature and humidity) in order to obtain the true airspeed, and for wind conditions in order to obtain the speed over the ground.
Magnetic compass
Shows the aircraft's heading relative to magnetic north. While reliable in steady level flight it can give confusing indications when turning, climbing, descending, or accelerating due to the inclination of the earth's magnetic field. For this reason, the heading indicator is also used for aircraft operation. For purposes of navigation it may be necessary to correct the direction indicated (which points to a magnetic pole) in order to obtain direction of true north or south (which points to the earth's axis of rotation).
Schempp-Hirth Janus-C glider Instrument panel equipped for "cloud flying". The turn and bank indicator is top center. The heading indicator is replaced by a GPS-driven computer with wind and glide data, driving two electronic variometer displays to the right.
Heading indicator
Also known as the directional gyro, or DG. Sometimes also called the gyrocompass, though usually not in aviation applications. Displays the aircraft's heading with respect to magnetic north. Principle of operation is a spinning gyroscope, and is therefore subject to drift errors (called precession) which must be periodically corrected by calibrating the instrument to the magnetic compass. In many advanced aircraft (including almost all jet aircraft), the heading indicator is replaced by a Horizontal Situation Indicator (HSI) which provides the same heading information, but also assists with navigation.
Turn and bank indicator, turn coordinator or turn indicator
The turn and bank indicator, also called the turn and slip indicator, displays direction of turn and rate of turn. Internally mounted inclinometer displays 'quality' of turn, i.e. whether the turn is correctly coordinated, as opposed to an uncoordinated turn, wherein the aircraft would be in either a slip or a skid. Replaced in the late sixties and early seventies by the newer turn coordinator, the turn and bank is typically only seen in aircraft manufactured prior to that time, or in Gliders manufactured in Europe.
A turn coordinator displays rate and direction of roll while the aircraft is rolling; displays rate and direction of turn while the aircraft is not rolling. Internally mounted inclinometer also displays quality of turn. Replaced the older turn and bank indicator.
Vertical speed indicator
Also sometimes called a variometer. Senses changing air pressure, and displays that information to the pilot as a rate of climb or descent in feet per minute, meters per second or knots.
Arrangement in instrument panel
Most aircraft built since about 1953 have four of the flight instruments located in a standardized pattern called the T arrangement. The attitude indicator is in the top center, airspeed to the left, altitude to the right and heading indicator under the attitude indicator. The other two, turn-coordinator and vertical-speed, are usually found under the airspeed and altitude, but are given more latitude in placement. The magnetic compass will be above the instrument panel, often on the windscreen centerpost. In newer aircraft with glass cockpit instruments the layout of the displays conform to the basic T arrangement.
See also
Glass cockpit
[edit] External links
Instrument Flying Handbook (FAA-H-8083-15A) 2007
The Gyro Horizon Enables Instrument Flying A history of how aircraft instrumentation was developed with an emphasis on the gyro horizon. (c) 2007
v • d • eFlight instruments
Pitot-static instruments: Altimeter · Airspeed indicator · Machmeter · Variometer
Gyroscopic instruments: Attitude indicator · Heading indicator · Horizontal situation indicator · Turn and bank indicator · Turn coordinator · Turn indicator
Navigation: Horizontal situation indicator · Course Deviation Indicator · Inertial navigation system · GPS · SIGI ·
v • d • eSatellite navigation systems
Historical
Transit (USA)
Operational
GLONASS (USSR/Russia) · GPS (USA) · Beidou (China)
Developmental
COMPASS (China) · Galileo (Europe) · IRNSS (India) · QZSS (Japan)
GNSS augmentation systems
EGNOS · GAGAN · GPS·C · LAAS · MSAS · WAAS · StarFire
Related topics
GNSS · GNSS reflectometry · Kalman filter
Other: Magnetic compass · Yaw string · Glass cockpit · EFIS
Retrieved from "http://en.wikipedia.org/wiki/Flight_instruments"
Categories: Aircraft instruments Aviation Display technology Measuring instruments Navigation Navigational equipment
This page was last modified on 1 July 2008, at 00:31.
All text is available under the terms of the GNU Free Documentation License. (See Copyrights for details.) Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a U.S. registered 501(c)(3) tax-deductible nonprofit charity.
Privacy policy
About Wikipedia
Disclaimers
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