Wibbly Wobbly (video link)

[SoundBarrier]

So I'm looking at aeroplanes doing strange things and this one thinks it's a wet dog shaking it's hair.

What's going on here, and why does it stop? It looks intentional, is it?

http://nz.youtube.com/watch?v=kQI3AW...eature=related

SB

[jb2_86_uk]

Although I have no knowledge about gliders whatsoever, given the way it rises when this phenonoma starts and falls when it finishes, I would be inclined to think it maybe has something to do with flying through a turbulent updraft/thermal.

I stand to be corrected!

JB

[Intruder]

Looks like flutter from overspeed.

[FE Hoppy]

yep thats flutter.

[Denti]

It's a flutter test flight. There are other nice videos out there from other flutter test flights, the most impressive i've seen was a flutter test with the sb-9 (glider plane as well).

Normally nowadays flutter tests are done on the ground, for gilder planes, at least german build ones, usually in the DLR labs in Göttingen (institute of aerolasticity).

[airfoilmod]

Agreed

My crap German tells me the pilot(?) was reading out A/S. He seemed too collected to be experiencing unexpected Flutter. Did you notice the left Aileron? How does it stay attached. That's a beefy airframe.

[Denti]

Yup, he starts with "Jetzt gehts los", basicly "it's starting now" and then he reads out airspeeds starting with 150 down to 130 (i would think km/h as that is the usual scale). Flutter is actively induced by aileron movement.