# A Conceptual Design Methodology for e-VTOL Aircraft for Urban Air Mobility
###### Abstract  
Recent progress of electric systems has raised attention towards hybrid-electric and full-electric aircraft. Nevertheless, the current low battery energy density limits the application of these propulsive architectures to large transport aircraft. In the context of the general aviation category, full-electric aircraft for the so-called Urban Air Mobility scenario are gaining increasing interest. These air taxis, also called e-VTOL, are conceived to exploit vertical take-off and landing capabilities, to carry people from one point to another, typically within the same city. In this paper, a new conceptual design methodology for urban air vehicles is presented and applied to an innovative convertiplane, called _TiltOne_, based on a box-wing architecture coupled with tilt-wing mechanisms. Several _TiltOne_ configurations have been designed according to the current regulations imposed by European Union Aviation Safety Agency, and sensitivity analyses have been carried out on the varying main design parameters, such as wing loading and propellers' disk loading, as well as main top-level aircraft requirements. The results provide an overview for today's operational capabilities of such aircraft and, in addition, depict possible scenarios for a near-future horizon, based on the assumption of increased performance levels for the electric powertrain components. In such scenario, two different concepts of operations are analysed and discussed: the first is based on a given design range, long enough to cover the urban distances; the second is conceived to exploit the capability of flying multiple shorter missions with a single battery charge. The designed _TiltOne_ configurations derived from these different approaches are presented, highlighting their potential capabilities and possible drawbacks. e-VTOL; air taxi; UAM; conceptual design; tilt-wing; box-wing +
Footnote †: journal: Applied Sciences  
_Article_  
A Conceptual Design Methodology for e-VTOL Aircraft for Urban Air Mobility  
[PERSON], [PERSON]. In the United States, UAM is part of the Advanced Air Mobility (AAM) programmes: Federal Aviation Administration (FAA), NASA and industry are collaborating to define a new aviation market, which exploits electric aircraft for intra-city (in the same city) and inter-city (between cities) transportation of people and goods [17; 19]. In 2016, Uber published a white paper on UAM, describing the benefits, in terms of time saved, emerging from the introduction of air transportation of people in high urban density scenarios and the main hurdles to enable UAM [18]. In [20], NASA reported how air transportation can mitigate the congestion by consistently reducing the travelling time. The air transport envisioned in [18; 20] is based on a ride-hailing service, in which people can book an air taxi using a mobile application. Although such service can be provided using vehicles with a pilot on-board, the long term vision consists of using air taxis capable to fly autonomously within the cities. On this point, it is worth emphasizing that if on the one hand the future capabilities of autonomous systems will allow air taxis to operate without human oversight, on the other hand, operator's accountability will certainly be a legal requirement. As a consequence, the presence of a \"ground pilot\", i.e., a supervisor located in a ground station, will also be needed in the future. To accomplish the mission in the most flexible way, air taxis have to be provided with Vertical Take-Off and Landing (VTOL) capabilities; therefore, they are sometimes referred to as \"e-VTOL\" to recall the electric propulsion. According to [18], the challenges that UAM needs to face for bringing benefits to travellers and the environment are: (_i_) reduced flight time in comparison to road transport alternatives; (_ii_) noise level below 67 dB; (_iii_) no noxious atmospheric emissions in flight; (_iv_) air vehicle must be safe and reliable.