..anyone an idea by looking at the mov?
I threw it with about 3/4 throttle
Plane is already fixed and witing for a now try... as soon as it stops raining.
For a start I added some more weight to the nose and build a new elevator.
A maiden is always something extra. I would never start my new plane without both hands on the radio. You dont have one sec to adjust if any trim is wrong. Next time ask someone to fly or to throw the plane for you until you get the trims set up.
If you need a lot of elevator trim then it is better to adjust the stablisor angle. The plane shall behave almost similar in speed from slow to fast.
I have seen the same as in your video with an ARF - just to much throttle and a little to much up trim on the elevator. Less than one sec to do the loop and land on your heels ;-)
I would be very surprised if the CoG should be any further than 25-30% from the leading edge.