[phantomworker]

Coanda Effect and its quieter than it would be if you hung the engines below the wing.

If the aerodynamics are that important, why isn't this concept being used on regular aircraft? Even though the engines might not pick up as much FOD (foreign object debris), it is not an efficient design. LOL! There must be politics involved in discussing this with Russia and Alenia. Politics is behind everything, imho.

[Paleo Conservative]

If the aerodynamics are that important, why isn't this concept being used on regular aircraft?

I don't think most planes need to land on short gravel runways. It pays for the short field performance with extra structural weight in the wing and shorter range.