Last year, the Austrian engineering firm IAT21 set out to construct a flying machine that floated like a hummingbird, traveled as fast as a jet, was as quiet as a hot-air balloon, and was simple enough that a car mechanic could repair it. The company's working prototype, called D-Dalus, is roughly one and a half by one square metre and can lift about 45 kilos. But the size and lift are not what's most impressive. A flying machine with no airfoil, rotor or jet propulsion can travel where most cannot: in very tight spaces and through terrible weather.
The craft's four rotors spin at 2,200 rpm, and six blades attached to carbon-fiber disks create directional thrust. The blades act as mini airfoils, their angle of attack constantly shifting in relation to rotation. For vertical lift, a blade's leading edge rises away from the centre of the disk at the top of its rotation and toward the centre of the disk at the bottom [pictured], creating a pressure differential.
Existing bearings were unable to withstand 1,000 Gs of force between the carbon-fibre disks and their blades and still deliver some degree of maneuverability. Engineers at IAT21 developed their own bearings, shaped like metal barrels, that hold up to the force better than spheres (think: arches) but can still roll enough for the blades to move.
Servo motors communicate with the rotor assemblies to automatically correct the craft's speed, position and balance by adjusting the blades' angle. If the pilot jerks the radio controls too hard in one direction, the craft will keep itself from pitching or yawing by increasing opposing thrust. The system can adjust for turbulence and heavy winds, too.
Radar, GPS and three multispectral cameras (visible, EHF-extremely high frequency- and infrared) act as the D-Dalus's eyes. Visual information is fed into the craft's collision-avoidance algorithm. The system is so sensitive that D-Dalus can fly within inches of power lines, hover above moving platforms (a ship's deck in rough seas, for example), or refuel another D-Dalus in flight.