High Speed Shaking

[Viper2000]

Originally Posted by RAF74_Winger

Wouldn't the damping ratio be increased at lower altitudes with denser air, leading to greater risk of instability/flutter higher up?

I don't know that, just asking the question.

W.

That's my understanding.

VNE of quite a lot of gliders decreases at high altitude for flutter avoidance (clearly gliders with a <150 KIAS VNE at sea level aren't bothered about compressibility ).

But I'm pretty certain that this behaviour isn't meant to be flutter, because you do it repeatedly without recourse to the refly button.

Some people fear flutter because they do not understand it; others fear it because they do.

I can't remember who coined that one, but it's certainly true; I've only seen it once IRL, and it ripped the aeroplane affected into bits in 3 cycles and probably 0.5 s. Thankfully it was unmanned, so it was just a case of picking up the bits. But it was a truly awe inspiring sight (and sound - first the aerodynamic buzzing, and then the structural failure, followed by almost total silence as the bits descended at terminal velocity). Unless you've had that sort of experience, you almost can't comprehend just how impressive the forces involved really are. Everybody who saw it had to pick their jaws up off the floor...