The desire for greener aircraft pushes both academic and industrial research into developing technologies, manufacturing, and operational strategies providing emissions abatement. At time of writing, there are no certified electric aircraft for passengers’ transport. This is due to the requirements of lightness, reliability, safety, comfort, and operational capability of the fast air transport, which are not completely met by the state-of-the-art technology. Recent studies have shown that new aero-propulsive technologies do not provide significant fuel burn reduction, unless the operational ranges are limited to short regional routes or the electric storage capability is unrealistically high, and that this little advantage comes at increased gross weight and operational costs. Therefore, a significant impact into aviation emissions reduction can only be obtained with a revolutionary design, which integrates disruptive technologies starting from the preliminary design phase. This paper reviews the recent advances in propulsions, aerodynamics, and structures to present the enabling technologies for a low emissions aircraft, with a focus on the commuter category. In fact, it is the opinion of the European Community, which has financed several projects, that advances on the small air transport will be a fundamental step to assess the results and pave the way for large greener airplanes.

Purpose: This work aims to deal with a comprehensive review of design methods for aircraft directional stability and vertical tail sizing. The focus on aircraft directional stability is due to the significant discrepancies that classical semi-empirical methods, as USAF DATCOM and ESDU, provide for some configurations because they are based on NACA wind tunnel (WT) tests about models not representative of an actual transport airplane. Design/methodology/approach: The authors performed viscous numerical simulations to calculate the aerodynamic interference among aircraft parts on hundreds configurations of a generic regional turboprop aircraft, providing useful results that have been collected in a new vertical tail preliminary design method, named VeDSC. Findings: The reviewed methods have been applied on a regional turboprop aircraft. The VeDSC method shows the closest agreement with numerical results. A WT test campaign involving more than 180 configurations has validated the numerical approach. Practical implications: The investigation has covered both the linear and the non-linear range of the aerodynamic coefficients, including the mutual aerodynamic interference between the fuselage and the vertical stabilizer. Also, a preliminary investigation about rudder effectiveness, related to aircraft directional control, is presented. Originality/value: In the final part of the paper, critical issues in vertical tail design are reviewed, highlighting the significance of a good estimation of aircraft directional stability and control derivatives.