Hi,
I thought I would post this here just in case as well. I have a new to me M4 that I've put together and installed a spirit GT on. It develops what can be described as a flight ending wobble randomly. I have attached a video:
https://youtube.com/shorts/P59WYXQuYOI?feature=shareOriginally, I assumed it was mechanical and ended up replacing the blades, the damper, the main shaft, the 3M Vibration resistant tape. I also played with the tightness of the blades. None of this resulted in fixing the wobble, and there was no consistency to when it would occur. Sometimes I get a few minutes of flying, sometimes it happened immediately. Sometimes it would start and solve itself as I tried to land.
Now I've moved onto the Spirit GT and thinking maybe its a cyclic feedback loop. I have my tail gyro at 1.10X and this looks more like a wobble then tail wag. I had my cyclic at 65%, and lowered it to 60%. I have adjusted my headspeed from 2200 RPM (in the video) down to 1800 RPM.
My next move was to try and reduce the cyclic down further to 50%. I am still unsure if this is resonance or a mechanical issue.
I should also note that I was told that based on my video I am running nearly 4000RPM. I do feel like its too fast but when I plug the spirit in and remove the blades and run my IU1 @ 70%, Spirit says I am at 1800RPM. So maybe there is something else afoot as well.