Abstract
In order to fulfill transportation demands, people have well-explored
ground, waterborne, and high-altitude spaces (HAS) for transportation
purposes, as well as the underground space under cities (namely, subway
systems). However, due to the increased burdens of population and
urbanization in recent decades, huge pressures on public transportation
and freight traffic are introduced to cities, plaguing the governors and
constraining the development of economics. By observing the fact that
near-ground space (NGS) has rarely been utilized, researchers and
practitioners started to re-examine, propose and develop flying cars,
which are not a totally novel idea, aiming at solving the traffic
congestion problem and releasing the strains of cities. Flying cars
completely differ from traditional grounded transportation systems,
where automobiles/trains are suffering track limitations and are also
different from the air flights in HAS for long-distance transfer.
Therefore, while observing the lack of specific literature on flying
cars and flying car transportation systems (FCTS), this paper is
motivated to study the advances, techniques, and challenges of FCTS
imposed by the inherent nature of NGS transportation and to devise
useful proposals for facilitating the construction and commercialization
of FCTS, as well as to facilitate the readers understanding of the
incoming FCTS. We first introduce the increased requirements for
transportation and address the advantages of flying cars. Next, a brief
overview of the developing history of flying cars is presented in view
of both timeline and technique categories. Then, we discuss and compare
the state of the art in the design of flying cars, including take-off
\& landing (TOL) modes, pilot modes, operation modes,
and power types, which are respectively related to the adaptability,
flexibility & comfort, stability & complexity, environmental
friendliness of flying cars. Additionally, since large-scale operations
of flying cars can improve the aforementioned transportation problem, we
also introduce the designs of FCTS, including path and trajectory
planning, supporting facilities and commercial designs. Finally, we
discuss the challenges which might be faced while developing and
commercializing FCTS from three aspects: safety issues, commercial
issues, and ethical issues.