Quadrotors are pretty cool vehicles, able to be tightly controlled from afar to do any number of things. We usually see them when they're performing well, but this video from UPenn shows them failing, often spectacularly.
The UPenn GRASP lab works with quadrotors every day, working to get them to fly in formation, build structures and other such tasks. But this video doesn't show them doing that. No, it shows them trying to do such things and just not getting there. Ouch.
Check 'em out in the video below.