Impact of Propulsion Technology Levels on the Sizing and Energy Consumption for Serial Hybrid- Electric General Aviation Aircraft Jonas Ludowicy 1 , René Rings 1 , D. Felix Finger 1 , Carsten Braun², Cees Bil 1 1 School of Engineering RMIT University GPO Box 2476 Melbourne VIC 3001 Australia ²Department of Aerospace Engineering FH Aachen UAS Hohenstaufenallee 6 52064 Aachen Germany Jonas.Ludowicy@alumni.fh-aachen.de Abstract. Serial hybrid-electric propulsion systems combine the advantages of combustion engines and electric motors. Additionally, they offer new design freedom. In the medium term, this technology might be the solution to more eco-friendly aviation. In this paper, the key technology parameters of general aviation aircraft with such powertrains are analyzed concerning their influence on maximum take-off mass and primary energy consumption. Besides, technological thresholds will be identified. It is found that a power-to-weight ratio increase of electric motors does not yield as large improvements as expected and that fully electric powertrains are the best solution for aircraft designed to minimum primary energy usage once a certain battery energy density is exceeded. ABBREVIATIONS cD = Coefficient of drag ICE = Internal combustion engine cL = Coefficient of lift MSL = Mean sea level DEP = Distributed electric propulsion MTOM = Maximum take-off mass DoH = Degree of hybridization ND = Not defined DP = Design point PEC = Primary energy consumption EM = Electric motor PEF = Primary energy factor GA = General aviation P/W = Power-to-weight ratio HP,SH = Degree of hybridization of power a for serial hybrids W/S = Wing loading 1100 Peer Reviewed