In the last ten years, different concepts of electric vertical take-off and landing aircrafts (eVTOLs) have been tested. This article addresses the problem of the choice of the best configuration. VTOLs built since the fifties are presented and their advantages, disadvantages, and problems are discussed. Three representative eVTOLs, one for each main configuration, are compared on five main parameters and three reference missions. The parameters are disk loading, total hover time, cruise speed, practical range, and flight time. The performance of the eVTOLs on the urban, extra-urban, and long-range mission is evaluated computing the time and energy required. The results show that the best configuration depends on the mission. The multirotor is more efficient in hover. The vectored thrust jet is more efficient in cruise and has a higher range. The lift + cruise is a compromise.

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Several researches are being carried out at the Politecnico di Torino with the aim of designing a high altitude very-long endurance/unmanned air vehicle (HAVE/UAV). Being able to fly in the stratosphere (15 -20 km) and with an endurance of about 4 months offers an advantage and possibility that is presently not available with conventional aircraft or satellites. A computer program has been developed to design the platform. The change in solar radiation over a period of a year, the altitude, masses, and efficiencies of the solar and fuel cells, as well as the aerodynamic, structural, flight mechanics, and aeroelastic performances have all been taken into account. Extensive use has been made of high modulus graphite/epoxy when designing the structure in order to minimize the airframe weight, but also to guarantee the required stiffness and aeroelastic performance.A blended wing body (BWB) configuration has been selected for solar HAVE aircraft multi payload and operation (SHAMPO) with eight brushless electric motors, as the result of a preliminary design. The BWB solution has been designed according to the conventional procedures and airworthiness regulations. It seems to be the best compromise between performance, available surfaces for solar cells and volume for multi-payload purposes, compared to conventional design.Several profiles and wing plans have been analysed and optimized to achieve the best efficiency using the Xfoil and Vsaero computational fluid dynamics (CFD) software. A finiteelement method and a classical theoretical analysis was carried out using the Msc/Patran/ Nastran code to predict the static and aeroelastic behaviour of the SHAMPO. Aeroelastic analysis has been performed starting with a classical linear flutter analysis and considering an undeformed equilibrium condition. Classical linear flutter speed show as the airworthiness requirements has been achieved in the case of SHAMPO configuration. A preliminary non-linear aeroelastic model is introduced in the design process in order to deal with specific phenomena correlated with high static structural deflections occurring during standard flight conditions. Important flutter speed reduction (i.e. up to 42 per cent in special cases) are possible including such kind of phenomena.