Ducted fans are an efficient way to power flying vehicles, but the devices remain largely unproduced because of problems with the control and reliability of their mechanisms. Most flying machines suffer from teething pains like this when they are still in their infancy. Jet turbines are a relatively new technology compared with many other combustion engines, but they see wide use because of their reliability and very high power output, despite not being terribly fuel efficient. Likewise, despite being difficult to control without complex computer controls, helicopters have proven popular due to their unique maneuverability. But, what if this same maneuverability were capable in a much more efficient package? This is what Rafi Yoeli is working on with his unmanned flying ambulance. Besides the efficiency of the ducted fan arrangement, the machine is a very efficient way to remove injured people from remote locations. Still, I don't expect to see anything like this any sooner that I expect to see the Moller flying car.
[Source: Popular Science]