Novice From United Kingdom, joined Aug 2012, 90 posts, RR: 0 Posted (3 years 1 month 3 weeks 6 days 1 hour ago) and read 3860 times:
If rectified airspeed is indicated airspeed corrected for pressure error and equivalent airspeed is rectified airspeed corrected for compressibility error, what is the differences in these two corrections?
larshjort From Denmark, joined Dec 2007, 1836 posts, RR: 0
Reply 1, posted (3 years 1 month 3 weeks 5 days 21 hours ago) and read 3815 times:
Quoting Novice (Thread starter): rectified airspeed is indicated airspeed corrected for pressure error
RAS=CAS Calibrated Airspeed
As far as I remember calibrated airspeed is corrected for the pressure drop that comes with increasing altitude. EAS then takes that number and corrects it for the compressability that happens when you reach near supersonic speeds.
Mir From United States of America, joined Jan 2004, 22551 posts, RR: 55
Reply 2, posted (3 years 1 month 3 weeks 5 days 21 hours ago) and read 3800 times:
Quoting larshjort (Reply 1): As far as I remember calibrated airspeed is corrected for the pressure drop that comes with increasing altitude.
Calibrated airspeed is indicated airspeed corrected for instrument error. When you correct for pressure dropping with altitude, you end up with true airspeed (correction for non-standard temperature is a part of that as well).
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Pihero From France, joined Jan 2005, 5011 posts, RR: 78
Reply 3, posted (3 years 1 month 3 weeks 5 days 20 hours ago) and read 3785 times:
A simpler way to remember all the relationships between the airpeeds : IAS + ki --> CAS x kc -->EAS x 1/sqrt d --> TAS
- ki is the instrument and position (of the pitot tube) error
- kc is the compreessibility error (to be ignored below 200 kt and 5000 ft )
- d is the air density
EAS is only ueed for aircraft performance, never in everyday piloting.