Hi Jim,
This is absolutely wrong. All airspeed limitations are IAS, Indicated AirSpeeds.
On the other hand, all performances figures are TAS, True AirSpeed.
Besides the instrument error, what your Pitot is senses and what your anemometer
indicates is exactly what affects the load on the structure of the aircraft.
Suppose you are doing 170kts True AirSpeed at 10000 feet. The density at this
altitude in standard atmosphere is 0.74. Your Indicated Air Speed will be 170
multiplied by the square root of the density, i.e 0.86, so your anemometer
will indicate 146 kts, which is far enough from Vne.
Remi Guerner
F-PGKL
Subject: Europa-List: Vne Speed
From: "h&jeuropa" <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
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