Die NASA vergibt 11,5 Millionen US-Dollar, um bei der Entwicklung der Flugzeuge von morgen zu helfen

The challenge with all these “airliner of the future” concepts we see decade after decade is practical, not technological. It’s expensive to service engines mounted above the wing. It’s expensive to redesign airport terminals to accommodate unusual cabin dimensions. It’s impossible to widen runways at many urban airports. 

It’s not that we can’t try, just that there are logistical reasons to stick with what works and they are awfully hard to change.