See
http://www.!!!!!!!!!!!!!!/discussions...d.main/217201/
My opinion?
Not impossible. Try to combine the good traits of An-225 and Airbus 380F.
200 tons of payload? An-225 has 250. 550 nm is long - An-225 covers just 2200 nm with full 250 t payload. But A380F gets pretty far at full 150 t payload.
Structural limitations? Ai-380 has MTOW of just 569 tons, and OEW like, 275 tons. An-225 has flown at 640 tons all up, and has mere 175 tons OEW. You could almost call Ai-380 overweight.
The cabin altitude requirement with BWB is problematic. You could stick to tube with wings.
Engine count? 4 is certainly doable. 2 probably not. But 3 could be feasible with off-shelf engines like GE90 or Trent 8104...