Runway-Independent Aircraft (tilt-wing, tilt-rotor, VSTOL, airships, wing-in-ground-effect) are steadily becoming more prominent in aviation. Examples of these concepts include Disc-Rotor technologies that marry the best features of a helicopter and an airplane. The Disc-Rotor program aims to develop a new type of aircraft capable of a seamlessly transitioning from hovering like a helicopter to flying like a plane. The design is propelled by rotor blades that extend from a central disc, letting it take off and land like a helicopter. However, those can also retract into the disc, minimizing drag and letting the Disc-Rotor fly like a plane, powered by engines beneath each wing.
Much of the current literature on runway-independent aircraft is devoted to concerns on noise pollution, due to increased jet blast hazards for vertical propulsion. Terminal traffic flows for this category of aircraft must also be closely coordinated with conventional traffic. Currently, vertical-takeoff technology is being analyzed by DARPA for use in unmanned aerial vehicles, which can require up to 4,000 feet of runway to take off under normal circumstances. The commercial sector, including companies such as Lilium, Airbus, and Uber, have put forth designs of their own meant for smaller-scale use, seating 5 people at maximum. Airbus’s design involves eight separate rotors, which can be tilted after takeoff to allow for horizontal flight, and a detachable passenger pod.
- Near misses during novel airport operations
- Failure to yield aircraft rights of way
- Airship loss of control during ground operations in wind
- Jet blast hazards in ground effect