AOPA members can check this out at
http://www.aopa.org/members/files/flttrain/aeronautical_knowledge/8083-25_ch
ap9.pdf
but the relevant definitions from the Pilot's Handbook of Aeronautical
Knowledge 2003 (FAA-H-8083-25) are quoted below:
True Airspeed (TAS) the speed of the airplane in relation to the air mass
in which it is flying.
Indicated Airspeed (IAS) the speed of the airplane as observed on the
airspeed indicator. It is the airspeed without correction for indicator,
position (or installation), or compressibility errors.
Calibrated Airspeed (CAS) the airspeed indicator reading corrected for
position (or installation), and instrument errors. (CAS is equal to TAS at
sea level in standard atmosphere.) The color-coding for various design
speeds marked on airspeed indicators may be IAS or CAS.
Equivalent Airspeed (EAS) the airspeed indicator reading corrected for
position (or installation), or instrument error, and for adiabatic
compressible flow for the particular altitude. (EAS is equal to CAS at sea
level in standard atmosphere.)
VA the calibrated design maneuvering airspeed. This is the maximum speed
at which the limit load can be imposed (either by gusts or full deflection
of the control surfaces) without causing structural damage.
VNO the maximum calibrated airspeed for normal operation or the maximum
structural cruising speed. This is the speed at which exceeding the limit
load factor may cause permanent deformation of the airplane structure.
VNE the calibrated airspeed which should NEVER be exceeded. If flight is
attempted above this speed, structural damage or structural failure may
result.
VSO, VS1, VX, VY, VLE, VFO, and VFE, are ALL in CAS. The FAA does not
mention RAS in this publication, probably because that term is not common on
this side of the Atlantic.
Best regards,
Rob Housman
A070
Airframe complete
Irvine, CA
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com]On Behalf Of Gerry Cole
Sent: Wednesday, December 13, 2006 1:52 PM
Subject: Re: Europa-List: Vne Speed
Jim,
If my memory is correct speeds are defined as follows:
Indicated Airspeed (IAS) = Instrument reading corrected for instrument
(mechanical) error.
Rectified Airspeed (RAS) is the 1940's British equivalent of the American
Calibrated Airspeed (CAS). They both equal Instrument reading corrected for
instrument error and position (pressure) error( I think there is some
difference between the two at high speeds and altitudes).
If you are lucky, on our kind of aeroplane there won't be too much
difference between IAS and RAS or CAS.
Both RAS and CAS are close to the scientifically pure Equivalent Airspeed
(EAS).
EAS = True Airspeed (TAS) x the square root of the relative air density. On
a Standard day (15 deg C at sealevel falling at a little under 2 deg C per
1000ft up to 36000ft) EAS equals TAS at sealevel, but at 10,000 ft an EAS of
150kts is equivalent to a TAS of 174.5kts.
I could be wrong but I thought design manoeuvring envelopes were defined in
EAS and cockpit placards showed IAS.
Gerry Cole , Classic 121
----- Original Message -----
From: h&jeuropa <mailto:europa@triton.net>
I have recently become aware that Vne is normally expressed in True Airspeed
(TAS). ?
Jim Butcher
XS N241BW
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