whirleybird is driven by a big motor in the middle, spinning the blades one way and, as per Newton, rotating the body of the craft the other. A tail rotor counteracts the force, but a more efficient solution is to have the rotors power themselves, which is exactly how the Dragonfly DF1 works. It has tiny, hydrogen-peroxide jets on the blade tips, spinning them up without pushing the body of the helo in the other way -- though a small tail rotor is still needed to turn the craft. It's much like the tech that propelled James Bond toward his waiting DB5 in Thunderball, but unlike that jetpack this copter can fly for up to 50 minutes. It's the product of Swisscopter Americas and, while they've been playing with the DF1 for many moons now (demonstrated in a video below), the company is also working on the DF2 shown above, a rather more civilized version that seats two. The DF1 is certified for flight in the US, looks to be available for sale and, while no price is listed, they are said to be much more friendly to the environment than traditional helicopters. That'll surely add to the premium.