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altimeter
- Definição1
- An instrument to indicate the height of an aircraft above a predetermined datum, normally sea level. Specifically, an instrument similar to an aneroid barometer that utilizes the change of atmospheric pressure with altitude to indicate the approximate elevation above a given point or plane used as a reference. A simple pressure altimeter is an airtight metal case, the interior of which is kept at atmospheric pressure by a tube connecting it to the static tube of the ASI (airspeed indicator). Inside the instrument case, a partially evacuated aneroid capsule is secured at the center of one of its faces to a base rigidly fixed to casing. A leaf spring prevents the collapse of the capsule. The capsule expands as aircraft gains height. The expansion of the capsule is converted into height through a system of gears. A pressure altimeter suffers from barometric, temperature, instrument, and lag errors. Radio or radar altimeters indicate heights above ground level.
- Fonte1
- KUMAR, Bharat (ed.). An illustrated dictionary of aviation. New York: McGraw-Hill, c2005. 752 p.
- Definição2
- An instrument that indicates flight altitude by sensing pressure changes and displaying altitude in feet or meters.
- Fonte2
- FEDERAL AVIATION ADMINISTRATION. Rotorcraft flying handbook (FAA-H-8083-21). Washington, DC: FAA, 2000. Disponível em: < http://www.faa.gov/library/manuals/aircraft/media/faa-h-8083-21.pdf >. Acesso em: 10 fev. 2012.
- Definição3
- An instrument that determines the altitude of an object with respect to a fixed level.
- Fonte3
- AMERICAN METEOROLOGICAL SOCIETY. Glossary of meteorology. [S.l., última modificação 05 oct. 2015]. Disponível em: < http://glossary.ametsoc.org/wiki/Main_Page >. Acesso em: 18 fev. 2020.
- Nota adicional1
- There are several types of altimeters: 1) the pressure altimeter, which measures barometric pressure and converts it to altitude above sea level when referenced to the existing measured sea level barometric pressure, or to pressure altitude when referenced to a standard pressure; 2) the radio or radar altimeter, which deduces altitude by measuring the time it takes a radio signal to travel from a transmitter to the underlying surface and back to the receiver; and 3) the Global Positioning System (GPS), which determines altitude by measuring time of travel of radio signals between GPS-equipped satellites and the receiver.
- Contexto
- As a result, altimeter indications are subject to errors, the extent of which depends on how much the pressure, temperature, and lapse rates deviate from standard, as well as how recently you have set the altimeter.
- Subárea1
- Flight Instruments
- Related Term
- height finder
- hypsometer
- Português
- altímetro
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