Last year's DARPA challenge proved that the more complex something is, the more ways there are for it to fail. This applies to drones just as it does to robots. With that thinking in mind, the creators of the Monospinner took a different approach to drone design, building a controllable craft that flies with just a single moving part: its propeller. What sets the Monospinner apart from those spinning propeller toys that blast off into the sky when you pull a rip cord is that you can control it once it takes off. It's not quite as manoeuvrable and nimble as an RC helicopter or the quadcopter drones that are currently popular, but there is still some impressive engineering at work here.
Helicopters usually require either a tail rotor, or a pair of rotors moving in opposite directions to prevent them from spinning out of control. The Monospinner doesn't use either and, in fact, it doesn't have any additional control mechanisms at all. Instead, it features an unusual, asymmetrical, off-balanced design that allows the craft to remain aloft and in complete control.
There are some trade-offs to this unusual design, with the most obvious being that it's almost impossible to shoot video from a craft that's constantly spinning. In addition to not being ideal for surveillance or filmmaking, at least in its current research form, the Monospinner requires a lot of external feedback to remain in the air. Outside the confines of a controlled sensor-packed drone arena, this craft might not perform so well, but as a proof-of-concept, the craft proves that every drone doesn't necessarily require four propellers to fly.