energies Article Conceptual Design of Operation Strategies for Hybrid Electric Aircraft Julian Hoelzen 1, Yaolong Liu 2,* ID , Boris Bensmann 1,*, Christopher Winnefeld 1, Ali Elham 3, Jens Friedrichs 4 and Richard Hanke-Rauschenbach 1 1 Institute of Electric Power Systems, Leibniz Universität Hannover, Appelstr. 9a, 30167 Hanover, Germany;
[email protected] (J.H.);
[email protected] (C.W.);
[email protected] (R.H.-R.) 2 Aeronautics Research Centre Niedersachsen (NFL), Technische Universität Braunschweig, Hermann-Blenk-Straße 42, 38108 Braunschweig, Germany 3 Institute of Aircraft Design and Lightweight Structures, Technische Universität Braunschweig, Hermann-Blenk-Straße 35, 38108 Braunschweig, Germany;
[email protected] 4 Institute of Jet Propulsion and Turbomachinery, TU Braunschweig, Hermann-Blenk-Straße 37, 38108 Brunswick, Germany;
[email protected] * Correspondence:
[email protected] (Y.L.);
[email protected] (B.B.); Tel.: +49-531-391-66662 (Y.L.); +49-511-762-14404 (B.B.) Received: 15 December 2017; Accepted: 12 January 2018; Published: 16 January 2018 Abstract: Ambitious targets to reduce emissions caused by aviation in the light of an expected ongoing rise of the air transport demand in the future drive the research of propulsion systems with lower CO2 emissions. Regional hybrid electric aircraft (HEA) powered by conventional gas turbines and battery powered electric motors are investigated to test hybrid propulsion operation strategies. Especially the role of the battery within environmentally friendly concepts with significantly reduced carbon footprint is analyzed. Thus, a new simulation approach for HEA is introduced. The main findings underline the importance of choosing the right power-to-energy-ratio of a battery according to the flight mission.