At 00:36 12 December 2003, Arnold Pieper wrote:
Jon,

The only way to reach VNE is by diving, not by fling
staight and level in
cruise.

Hope you dont mean that literally Arnold! I had a go
in a microlight once that had a cruise speed only 10kts
below its VNE!!- very easy to exceed vne in straight
& level. Plus in a glider if the wave/ridge is strong
enough you can get to VNE can't you?

Apart from that I think you explained the whole altitude/
density/ flutter /vne faff quite well.

Some people around here have incredibly complicated
ways of explaining things! With that in mind, for
the next debate can I suggest an explanation of :

Transition level, transition altitude, transition layer
and altimeter settings!? QFE QNH SPS....

AAARHGH NO! on second thoughts spare us!! :-) :-)



And you can dive from 1000ft or from very high altitudes.
All the while the VNE is that radial line painted on
you ASI, which reads
Indicated Airspeed and has to be respected as you see
it (not in your mind
or in some calculator).
The exception for limits related to flutter in Gliders
are done in the form
of a table so that you don't have to do mental math.

VNE is usually set at some % below whatever fenomenon
determined it.
It might be different things for diffent aircraft,
sometimes as simple as a
windshield that will not resist above a certain pressure,
or even the
position of the glider (VNE for inverted flight is
different from upright).
So, if you dive and your ASI pointer goes above that
radial line that marks
VNE,
bad things will happen, regardless of altitude.

The ASI 'underreads' at any altitude above Sea Level
@ ISA conditions.
The aircraft surfaces 'feel' the air the same way the
ASI does, which means
most
aerodynamic reactions respond to the same Indicated
Air Speed, regardless of
altitude.
That's why your Stalling Speed is at the bottom of
the green arc, and it is
the same at 1000ft or at 10000ft.
Same holds true for gear extension/operation speed
limits, flap speed
limits,
storm window speed limits and so forth.

The stuff that is REQUIRED by regulations to be painted
on the ASI, are all
reactions that remain constant with Indicated Airspeed,
that's why they are
painted on it.

The events that will occur at different IAS with different
altitudes are NOT
painted on the ASI exactly because they vary.
They are related to Power (HP, SHP or LBS of Thrust),
which always reduces
with altitude.
Examples are Vx and Vy for power airplanes, Vmc (for
twins) and things like
that.

Not so with VNE witch is painted-on.
The reactions to flutter on gliders will however, require
'new' VNEs at
higher altitudes, if you review all recent postings
on these 'tables of VNE
with altitude' it will become clear.

AP


'Jon Meyer' wrote in message
...
I think you misunderstood what I meant.
The IAS VNE at cruising altitude of 20000ft is 272kts
(assuming as I said before that IAS VNE is at cruising
altitude) . This equates to a TAS of 364kts. Which
means that VNE is 364kts TAS.
(.....................)