Arnold Pieper wrote:

Eric,

Thanks, I see how explicit they are about it.
DG chose to not get into specifics, because the story is a bit more complex
than that.

Even though they are explicit about it, I'm not sure if the reason is
regulatory or physical. An aeronautics fellow told me flutter doesn't
strictly follow TAS, but is somewhat higher, but testing at high
altitudes is needed to confirm exactly where it is.

The VNE of your glider is 146Kt (IAS), but above 10000' you should start
observing other IAS limits, that translate into 162Kt TAS due to flutter
considerations.

Again, I'm not sure where the 10,000' comes from: possibly below that,
Vne is restricted to IAS for reasons other than flutter, but above that,
flutter becomes the critical factor.

Therefore, simply using 146Kt as a TAS value is not correct, which is what
was being suggested earlier, and is what I had trouble with.

Nowhere in Aeronautic literature is VNE defined as a TAS value, it HAS to be
presented to the pilot as Indicated.

My glider manual does require a placard giving that information.

In high-performance aircraft where flutter is less of a consideration, there
is no such table for high altitude, VNE is always VNE, until MMo becomes a
factor.

It would be interesting to know why there is a difference, but I suspect
it might the regulatory requirements for different categories.

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Eric Greenwell
Washington State
USA