I remember a few years ago seeing pictures in Flight International (and others), of what I think were called prop fan, which looked kind of like broad propellers located at the back of what looked like jet engines. I remember in particular a picture of what I think was a DC9. I believe at the time, the big plus that was claimed were significant cost savings.
What happened to this development path - is it continuing or has it died, and if so, why ?
I have just found a Russian example
http://www.rob.clubkawasaki.com/jas4159.jpg