I know of very few ducted fans that could create a usable amount of thrust with only 4 of them. This is one of them:
The manufacturer claims it will make 56.8 pounds of thrust. The problem is that it would take 30kw of power with 2 of these to make 100 pounds of thrust. For comparison it only takes roughly 13kw of power to make the same thrust with a properly built single prop unit.