VNE Revisited

In our January issue, we ran an article, "Slow Down, You Move Too Fast," which focused on aerodynamic flutter, how high speeds can cause it and what can be done to minimize it. One aspect of the article drew comments and criticism from readers, some of which were published in the Unicom section in our March issue, involved that articles statements referencing a fixed-wing aircrafts never-exceed speed (VNE) as a true airspeed. Many readers rightly took us to task for those statements, pointing out VNE is an indicated airspeed-at least when published for the airplanes they fly-expressing skepticism and questioning our veracity. This article is an attempt to both respond to those valid criticisms and set straight the record associated with never-exceed speeds and our original statements.

Key Takeaways:

• The article corrects a previous error, clarifying that VNE (never-exceed speed) is typically an indicated airspeed (IAS) for most personal aircraft, though it can be a true airspeed (TAS) for certain specialized aircraft.
• A crucial distinction is made: while VNE is often an IAS, the actual onset of aerodynamic flutter, which VNE is designed to prevent, is fundamentally a function of true airspeed (TAS).
• This means that flying at VNE at higher altitudes can erode the safety margin against flutter, especially for older aircraft, because the increasing difference between IAS and TAS brings the true airspeed closer to the critical flutter speed.

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