36:
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for aircraft control, CAS (and EAS) are the primary reference points, since they describe the dynamic pressure acting on aircraft surfaces regardless of density, altitude, wind, and other conditions. EAS is used as a reference by aircraft designers, but EAS cannot be displayed correctly at varying
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and other advanced navigation systems in cockpits, the first application is rapidly decreasing in importance – pilots are able to read groundspeed (and often true airspeed) directly, without calculating calibrated airspeed as an intermediate step. The second application remains critical,
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however – for example, at the same weight, an aircraft will rotate and climb at approximately the same calibrated airspeed at any elevation, even though the true airspeed and groundspeed may differ significantly. These
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altitudes by a simple (single capsule) airspeed indicator. CAS is therefore a standard for calibrating the airspeed indicator such that CAS equals EAS at sea level pressure and approximates EAS at higher altitudes.
198:, CAS is defined as a function of impact pressure alone. Static pressure and temperature appear as fixed coefficients defined by convention as standard sea level values. It so happens that the
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A free windows calculator which converts between various airspeeds (true / equivalent / calibrated) according to the appropriate atmospheric (standard and not standard!) conditions
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Some authors in the field of compressible flows use the term dynamic pressure or compressible dynamic pressure instead of impact pressure.
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79:
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912:(EAS). In practice compressibility error is negligible below about 3,000 m (10,000 ft) and 370 km/h (200 kn).
202:
is a direct function of temperature, so instead of a standard temperature, we can define a standard speed of sound.
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for navigation, CAS is traditionally calculated as one of the steps between indicated airspeed and true airspeed;
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or accurate pressure gauge. If using a water manometer to measure millimeters of water the reference pressure (
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50:
44:
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are usually given as IAS rather than CAS, so that a pilot can read them directly from the airspeed indicator.
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A free android calculator which converts various airspeeds according to atmospheric characteristics
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airspeeds, where a normal shock forms in front of the pitot probe, the
Rayleigh formula applies:
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These formulae can then be used to calibrate an airspeed indicator when impact pressure (
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The supersonic formula must be solved iteratively, by assuming an initial value for
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conditions (15 °C, 1013 hPa, 0% humidity) calibrated airspeed is the same as
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135:(GS). Under any other conditions, CAS may differ from the aircraft's TAS and GS.
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JavaScript
Calibrated Airspeed calculator from True Airspeed and other variables
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At higher altitudes CAS can be corrected for compressibility error to give
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These formulae work in any units provided the appropriate values for
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In some applications, notably
British usage, the expression
1016:(12 MB), p. 15, NASA Reference Publication 1046.
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Airspeed corrected for instrument and position error
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131:(TAS). If there is no wind it is also the same as
194:Since the airspeed indicator capsule responds to
969:, pp 31, 32. Pitman Publishing Limited, London.
165:CAS has two primary applications in aviation:
146:, while indicated airspeed is abbreviated as
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1014:"Measurement of Aircraft Speed and Altitude"
417:is the standard speed of sound at 15 °C
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318:{\displaystyle CAS=a_{0}{\sqrt {5\left}}}
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80:Learn how and when to remove this message
810:= 1,225 km/h (661.45 kn). The
157:is used instead of calibrated airspeed.
43:This article includes a list of general
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922:Acronyms and abbreviations in avionics
637:{\displaystyle CAS=a_{0}\left^{(1/7)}}
7:
875:) may be entered as 10333 mm
49:it lacks sufficient corresponding
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1002:Jet Transport Performance Methods
121:International Standard Atmosphere
386:= standard pressure at sea level
190:Calculation from impact pressure
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1008:: Boeing Commercial Airplanes.
814:for air is assumed to be 1.4.
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209:speeds, CAS is calculated as:
1:
161:Practical applications of CAS
108:corrected for instrument and
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756:are selected. For example,
177:With the widespread use of
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1038:Newbyte airspeed converter
142:is usually abbreviated as
1012:Gracey, William (1980),
812:ratio of specific heats
410:{\displaystyle {a_{0}}}
138:Calibrated airspeed in
64:more precise citations.
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898:{\displaystyle H_{2}O}
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965:Clancy, L. J. (1975)
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868:{\displaystyle P_{0}}
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837:{\displaystyle q_{c}}
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722:{\displaystyle P_{0}}
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692:{\displaystyle a_{0}}
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379:{\displaystyle P_{0}}
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350:{\displaystyle q_{c}}
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1000:Blake, Walt (2009).
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1045:at luizmonteiro.com
932:Equivalent airspeed
910:equivalent airspeed
665:{\displaystyle CAS}
125:equivalent airspeed
98:calibrated airspeed
942:Indicated airspeed
937:Flight instruments
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18:Rectified airspeed
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110:position error
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70:September 2010
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133:ground speed
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62:introducing
953:References
423:supersonic
127:(EAS) and
45:references
846:manometer
672:equal to
592:×
555:−
503:×
303:−
117:sea level
1059:Airspeed
1053:Category
916:See also
207:subsonic
184:V speeds
106:airspeed
94:aviation
1006:Seattle
327:where:
58:improve
973:
119:under
47:, but
140:knots
971:ISBN
729:and
421:For
205:For
148:KIAS
144:KCAS
600:3.5
596:1.2
587:2.5
567:2.5
179:GPS
102:CAS
92:In
1055::
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96:,
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888:2
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861:0
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660:S
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630:)
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253:(
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243:5
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232:a
228:=
225:S
222:A
219:C
100:(
83:)
77:(
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68:(
54:.
20:)
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