Another offshoot of the dual counter-rotating blade concept is a class of machine called a flying platform. This design originated in the mid-1940s with engineer Charles Zimmerman's notion that the instability of overhead rotors could be overcome if the operator stood above the blades, controlling the machine with body movement; he called this his "flying shoes" concept. Aviation pioneer Stanley Hiller made a version of the flying platform that flew in 1955. Today's Hummingbird, made by the Israeli firm Aero-Design & Development, is a typical current example. A little over 7 feet in diameter, the machine resembles a giant tuna can; it contains two sets of counter-rotating propeller blades and is powered by four tiny 22-horsepower engines. The operator stands in a waist-high cage affair on top. The Hummingbird can reportedly fly for about 30 minutes. AD&D says it hopes soon to sell the machine as a kit for about $30,000. At 320 pounds, it's above the FAA's ultralight limits, but build-it-yourself kits are exempted from these rules. The Performance Aviation Manufacturing Group in Williamsburg, Virginia, meanwhile, is already taking orders for a $50,500 kit for a similar flying platform design called an Individual Lifting Vehicle. Company officials say it could be used by ranchers to track cattle (a personal ranching machine, an aero-horse) or by immigration officials to patrol borders.
And so it goes. There's no end to the iterations of this idea. Rafi Yoeli, an Israeli engineer, ex-Boeing, has a 1,200-pound prototype in his Tel Aviv living room of a machine called the CityHawk. A two-seater powered by twin gas engines and a pair of 6-foot-wide internal fans (one in front of the other, on a machine that looks a bit like a giant sandal), it relies on a computer-controlled system of 300 flaps to translate the pilot's commands-or will, if CityHawk ever flies.
Now stop for a second: Imagine personal airspace, filling up with CityHawks, AirScooters, SoloTreks, and Skycars. How likely is that? Not very likely anywhere near the suburbs. Paul Takemoto, an FAA spokesperson, notes that the fine print of Part 103, the regulations governing ultralight craft, requires pilots to fly low enough that they can always see the ground, and much more significantly, forbids flying through congested areas, in controlled airspace, or even over open areas where lots of people might be congregating. Furthermore, if commercial sales of personal flying machines were ever to really take off, the FAA would no doubt leap to provide additional oversight. "We certainly wouldn't hesitate to take another look at these regulations if we ever felt the need to do so," Takemoto says, no doubt with considerable understatement.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.