IAS is what you see on the ASI
CAS is IAS corrected for instrument error, errors in manufacture or
calibration
RAS is CAS corrected for Position Error
EAS is RAS corrected for compressibility Error
(only applicable to 200 hp turbo charged Europas)
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Andrew Sarangan
Sent: 13 December 2006 13:26
Subject: Re: Europa-List: Vne Speed
RAS is not a commonly used term, but it means Rectified Airspeed, which
is the same as Calibrated Airspeed (CAS). CAS is the Airspeed corrected
for installation errors.
--- "h&jeuropa" <europa@triton.net> wrote:
> <europa@triton.net>
>
> I have recently become aware that Vne is normally expressed in True
> Airspeed (TAS). According to Derek Piggotts Gliding text, it
> is important to limit indicated airspeed so the true airspeed is kept
> below the Vne placard speed. Otherwise there may be risk of flutter
> and structural failure.
>
> My XS Owners Manual states that Vne is 165 kts (page 2-1, issue
> 1). The same manual states that for a 914 typical performance is
> Cruise speed (100% @ 10,000 ft) 170 kts TAS (page 12-2, issue 1).
> But that is 5 kts greater than Vne!! That page also states Top Speed
> (sea level) 144 kts RAS. What is RAS? Is it a typing error (R is
> adjacent to T on a keyboard)? RAS is also referred to on the 912
> performance page.
>
> What are the performance numbers for the MG? Brochure says 151 kts
> TAS max cruise speed for 914 at 10000 ft. So is 151 KTAS Vne?
>
> It is very easy to exceed 165 KTAS when descending from altitude.
> Should this be avoided?
>
> Jim Butcher
> XS N241BW
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=81100#81100
>
>
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>
Andrew Sarangan
http://www.sarangan.org
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