RE: What does flutter sound like?
Sounds like a vibrating drum and the sound varies from plane to plane. Large open frame panels will resonate like a drum head and may have a snare snap to them. Solidly built structure will have a lower-pitch buzzing sound. If your engine is screaming you might miss flutter of a small surface. Furthermore, just because it didn't flutter this time doesn't mean that it won't next time. Thirdly, if it does flutter and survives, don't assume it will withstand it a second time, or a third, or a fourth.
I can pretty much agree with those warning you about your flying. Unless you have a well-tuned, solidly-built ship, doing that 100 mph stuff will eventually tear your plane apart.
Normal sport linkages and servos are too sloppy and one day soon you are going to fold the wing up on that trainer airplane doing full-throttle pull ups. don't mean any offense, but take some advice and slow it down until you get a better airplane.
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