On Sunday, November 10, 2019 at 7:02:57 AM UTC-8, Echo wrote:
Haven't read that, would be an interesting one though. I'd always been under the impression Vne is a flutter protection speed. That's why it's a TAS that doesn't change with weight like Va. Wouldn't be surprised if it was from some old math though.

I always thought Vne was an operational limit to airworthiness, usually derived from the flutter speed. Also that flutter speed was an odd power function of altitude (because it varies somewhat with density but not as fast as IAS, therefore TAS is safe). Also that it is an oscillatory phenomena which depends on the stiffness, mass, and forcing function - so practically does depend on weight (or at least mass), particularly of the wings but secondarily the fuselage. But that function would be way too complicated to put on the placard or even into regulations so no change is assumed.

I also didn't think it was required to air test flutter speed anymore, but could be calculated with mass, stiffness, and CFD codes.