This ornithopter (Russian form the looks/sounds of it) recently flew in a controlled manner. It looks like it was a rough ride; it’s not clear to me what practical advantage such a system has over pretty much *any* other form of aerial locomotion beyond “because it’s cool.” Which is, of course, reason enough to do pretty much anything.
An earlier flight of a prior iteration did not go so well.
An even earlier flight of an even earlier iteration *did* fly successfully, if slowly and incredibly loudly:
A video of the designers. Turn closed captioning on to read what they have to say:
I suppose if they could improve the system so that it takes off and lands vertically, then switches to fixed-wing forward flight with a conventional propeller, it might turn out to be an efficient-ish drone for some applications.