ORIGINAL: flutter caused it
Thinn , I also have just purchased an Osmose. I had always wanted one and finally took the plunge. After reading most of the threads, I was excited to get started, that is until I got to yours. Your thread stated that no matter where you located the ''CG'', the plane dives towards the ground while inverted. Are you still having this issue? And is anyone else familiar with this characteristic pertaining to the Osmose 70? If others are sharing this ''diving'' while inverted, I think I may not build the plane. I was hopeing for it to be fairly neutral in all axises. Is this wishful thinking.
I don't think you should worry too much about this... Any pattern plane will dive some inverted (OK, some will surely arrest me here...).
On ARF's there is not too much to to with the incidences, as everything is fairly finished.
I still have not tried mine with the slight incidence change on the main wing, but I do belive this is a minor issue, and is easy to overcome if it is a problem (as in my case). The plane is more than capable as is, but I like my planes to be a bit more "neutral" - dive slightly less inverted.