Re: that Junkers Ju-390 reminds of the Nakajima G10N
The Junkers Ju-390 had a type of gull wing in which outboard of the outer engines the anhedral cranked upwards. The aifoil also had a very thick chord and I don't believe from published speed predictions from the Nakajima G10N that their wings were similar at all. My opinion is that the G10N was more influenced by publicity about the B-29 Hobo Queen which visited England in March-April 1944 with great fanfare of publicity.
The Ju-290 and Ju-390 were limited to a maximum cruise speed of just 232 knots. Test pilot Hans Werner Lerche described flying the Ju-390 and said that tight banking induced dangerous wing flutter. This is a situation where the wing tip on the outside of a turn flies slower through the air than the wing tip on the inside of a turn causing the outer wing to shudder near stalling.
At least one Ju-290 A8 (bomber with nose & tail machine gun) disappeared from Germany in January 1945. The second unfinished Ju-290 A8 airframe became the Letov Le.290 Oriel airliner.