Very exciting project! Love the idea, and can't wait to see some proof of concepts eventually. It obviously has the potential to be revolutionary in the aerospace industry, though time will tell if it's as effective as claimed of course.<p>They compare the TURN concept to satellites in the beginning, mentioning only positives by comparison - of which there are indeed many (cheaper, better comms). One thing I didn't see mentioned was the failure mode between the two. A satellite that ceases to function will stay in orbit, until this orbit decays enough for it to burns in the upper atmosphere. If one of the rotors on this device fails, it will just come crashing down to earth.<p>And also, in typical neo-luddite fashion, I'm fearful for the surveillance applications of this device. Even if staying airborne isn't eventually completely free (eternal flight) with this system, the ability to stay up for 9 hours at a time on a few Li-Ion cells opens up a world of possibilities, not all of which are great. If NOAA can afford to put a number of these out in the Atlantic to get better atmospheric readings, surely cities, states, city-states, and others can afford to put a number of these above their populace.<p>However, progress is inevitable, and the technology can't always be blamed for it's potentially negative applications. I think this is an amazing project - but it will require some self-control to not let this push us further into a surveillance state.