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*[http://en.wikipedia.org/wiki/Equivalent_airspeed '''Equivalent''' airspeed (EAS)] takes into account another correction (above [[#Calibrated airspeed]], this time having to do with air properties rather than sensor errors. | *[http://en.wikipedia.org/wiki/Equivalent_airspeed '''Equivalent''' airspeed (EAS)] takes into account another correction (above [[#Calibrated airspeed]], this time having to do with air properties rather than sensor errors. | ||
At high altitude, the compressibility of air changes, so even CAS becomes more and more unreliable. For the [[SR-71]] Blackbird with a ceiling of 85.000 feet, the CAS becomes very unreliable and the plane has to be flown based on a EAS. For more conventional aircraft, EAS is not used. Thus, EAS is what a perfect dynamic pressure sensor would show when properly calibrated for the air compressibility at the current altitude. The EAS is the calculated result from the ram pressure (measured by the [[#pitot tube]]) and the static pressure (measured by the [[altimeter]]) | At high altitude, the compressibility of air changes, so even CAS becomes more and more unreliable. For the [[SR-71]] Blackbird with a ceiling of 85.000 feet, the CAS becomes very unreliable and the plane has to be flown based on a EAS. For more conventional aircraft, EAS is not used. Thus, EAS is what a perfect dynamic pressure sensor would show when properly calibrated for the air compressibility at the current altitude. The EAS is the calculated result from the ram pressure (measured by the [[#pitot tube]]) and the static pressure (measured by the [[altimeter]]). | ||
=== Mach number === | === Mach number === |
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