I’m quite used to this so if I had the aircraft I’d fixed it for you than uploaded it on my alternate account wich by the way is CVabondonedprojects@Kungfuevan

Hey I could fix this for you very easily @Kungfuevan

I don;t think it's too light or too maneuverable. I think your vertical stabilizer is too small. When I fly the plane it doesn't like to go straight, it like to weave left to right and back again. I think that's part of why the plane "flips sideways." I also think that because you use your entire tail for a horizontal stabilizer, the plane looses stability when pitching up or down.

I'd suggest trying a larger vertical tail, and add a strip of wing in front of each horizontal section that doesn't move when the rest of the tail pitches. I think those two changes would make the plane more stable and help eliminate the jerking motion.

Thanks @Andrewtheplane

@Kungfuevan It turns so quickly that the whole airplane is to light to handle it and flops like a feather in the wind

Elaborate@Andrewtheplane

@Kungfuevan you made it to manuevrable

https://www.simpleplanes.com/a/4xxkOQ/Fokker-e-111

You probably have elevator stall. Reduce deflection of elevators.

Could you give us a link to the plane?

Your plane is either
(A) Unbalanced, center of mass off center line of aircraft

Or

(B) Some combination of too heavy, main wings too small, center of mass too far forward, elevators too large, center of lift too far back

I have a cool way of solving this if nothing works. Put airbrakes on both sides of your plane which are activated by either VTOL or throttle, then nudge them in your plane so they aren’t seen when used. They balance out the plane most of the time

Hard to determine without looking at the plane:

• Is the drag, CoM and CoL symmetrical, is the CoM clearly ahead of the CoL?

• Are the elevators surfaces very large; I know large elevators can cause instability.

• Is the rudder central and decently sized? Is it large enough to keep the plane stable?