@ErnstHeinkel16 The unusual proportions of the fuselage in conjunction with the small horizontal stabilizer w/oversized elevator I think is part of the problem, as that moves the center of lift forward and causes exagerated changes in pitch, even when balast is added to the forward portions of the craft, fuel in the nose, etc. The low wing loading is responsible for the center of lift to be so large at its position and that's due to the broad chord wings and small horizontal stab. This reminded me of a fictional design from a show I saw once upon a time. Another issue is the lack of landing gear at its present state of development. That frequently changes weight arrangements. Given that you wanted to keep the aesthetics of this bird though I'm not sure what I can and cannot change aside from shifting around fuel/balast, adding a 20 gallon tank into the nose which is another 177 Lb. Even when pulling the center of balance to mid-canopy she was still unstable and I can only guess it's the horizontal stab/elevator. I'm sorry I wasn't more help...

@ErnstHeinkel16 I'm a sucker for twin booms, lemme give it a shot.

I tried that. It went normally for a while then it flipped backwards.

Hey dude. All you need to do use the feature to show you the location of the Center Of Lift and Center Of Mass, then edit the fuselage features at the front to add weight or fuel and shift the Center of Mass, the red orb forward ahead of the blue. You might also need to reverse the rotation of the prop since its on the back yea?