On Wed, 09 Mar 2005 21:52:58 GMT, "Mike Rapoport"
wrote:


"T o d d P a t t i s t" wrote in message
.. .
"Mike Rapoport" wrote:

I've never heard of Vne being related to TAS, only IAS. It makes no
sense
to me. Could you provide a reference?

Vne is a fixed mark on the airspeed indicator and,
as such, doesn't move.

Despite the Vne mark on the altimeter, it definitely is not
a fixed IAS (or CAS) number. Nor is it always a fixed TAS
number. It is the number defined by the manufacturer that
is usually found in the flight manual. My sailplane has a
Vne that drops with altitude, and while it's closer to a
fixed TAS than IAS, it's not exactly either.

A fixed TAS makes sense because it is often flutter that
sets the Vne limit, and flutter is a timing related issue
that relates to TAS more closely than IAS.

"It is possible to fly without motors, but not without knowledge and
skill."
Wilbur Wright

So what is the mark on the airspeed indicator supposed to mean then? I have
never seen anything in any of the flight manuals that I have (four)
referring to Vne going down with altitude. I am not disputing that it does
but I am mystified as to why it isn't better explained in flight manuals.
Similiarly, Vmo is given as a single IAS number. In the MU-2 Vmo is 250kts
IAS at any altitude up to about 22,000' where the Mach limit takes over.
This is a large range of TAS. Is it perhaps actually related to Mmo rather
than Vne as gliders don't have airspeed indicators with barber poles? Can
you give some examples wth real numbers and altitudes?

Mike
MU-2


It is confusing. Because the high end of the red arc on the ASI is
described as Vne, it certainly would suggest Vne is an IAS and can
be flown as such. But this is not what many glider POH instructions
state.

I don't have a POH here at work. I'll try to remember to give you an
example from one of the ones I have.