The Dr-! (and similar rotary motored planes) had too much of the mass of the equipment in the plane mounted directly over the fulcrum of the axle.. that's a long moment arm which makes overturning sooooooo easy!
My Dr-1 finishes most landings upside down!
There's no mass behind the c.g. to prevent the tail from tipping up.
Takeoffs are also a problem, requiring up elevator to prevent the tipping, but also demanding its release ASAP to prevent a tip-stall takeoff!