Here's a strange one.
Got my TBS Disco back in the air after a couple of crashes due to a faulty ESC.
But there seems to be some strange vibes that weren't there before.
Noticable in the GoPro footage at hover, but mainly when cranking it up a bit. As you can see in this video. It appears to dip to the left when the vibes kick in, and attitude control is no longer tight. Lift off slighty and it kicks back, and the vibe vanishes instantly, and normal "on rails" flight resumes.
This looks like a harmonic vibration, but from what? I've tightened everything up, the props are balanced, checked and checked again.The motor bells are tight, and there's no noticable bearing issues. It should be a motor - a left one most likely - but nothing is loose that I can find. The picture is of the motors spinning at 100% without props on a solid metal bench - looks ok?
Additionally, I get massive interference on the pilot camera that appears to corrospond to periods when throttle is high and the reasonance is present.
Knock back the pace a bit, and it flies no problem.
Unfortunately, logs were factory fresh, so no IMU or MOTOR stats. But hopefully someone can tell whats up?
Replies
resonance happens in a certain weight distribution/prop frequency/frame type. I guess you found the unlikely winning combination of components. My suggestion would be to add or remove weight at certain places in your frame until the resonance disappear. Maybe change prop pitch too.
The TBS arms are plastic aren't they ? Theu are porbably not so rigid and twist. Try rigidify them to see if it changes the resonance.
also what frame are you using ? plastic ? Aluminum ? CF ?
does the frame flex, especially the arms ?
What's the total weight ?
Can you say what motors model, KV and prop size/pitch you have ?
Ok, some more data.
It gets even stranger. This is the harmonic:
Vibes:
It all looks normal, apart from the bits where I get massive reasonance!
I also seem to be getting massive interference on the video (black lines, not static) which gets worse on full throttle. I'm using a SC2000 cam, on the TBS core (shielded).
Still looking for suggestions...meantime, it's getting dismantled to look for something loose inside. Worrying is the interference on the video.
2013-11-09 11-27 1.log