It sounds like a B-17 when it flies over.
That may have been acceptable in 1944, but in 2006, no way.
UDF's are deader than than dead. They looked so good on paper....
Yes, UDF (Un-Ducted Fan) was another acronym for them as well.
However, thanks to better gearbox designs since then (which allow the switch to ten-bladed propfans), this will allow for slower fan speeds with far less noise and less danger in case of blade failure. The Fozzie concept could actually work for an airline like Southwest Airlines flying routes under 900 nautical miles in length, where cruise speed performance is less critical. For example, this plane would be perfect for Southwest's intra-California routes and routes between California and Nevada/Arizona; another place such a plane would be useful is intra-Texas routes.