Those are really neat John. I especially like that top one. Functionally, I don't know, but the cool factor is really high. I'll bet that EDF one at the bottom is really inefficient. Those are some interesting finds. ...Tiger
The top one is my favorite also but I would have done a few things differently. For example I think the camera dome should have been more forward in front of the two forward propellers. It does appear to be a really quality job though. The tricopter is nice in that they did a great job with the frame. As I posted previously in another thread, those "Y" sixes can suffer some failures well. The ducted fan quad seems to be a proof of concept and I agree with you that it doesn't seem it would efficient. I also imaging that it would be slow responding to stick inputs while the turbines spin up and down. I bet it sure sounds cool though!