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Hybrid-electric propulsion – situation and challenges

The introduction of electrical energy into the scheme of aircraft propulsion and power opens a broad variety of system architectural options that poses additional challenges to overall systems design. In order to find best-suited technical concepts for a given application case, large configurational design spaces need to be evaluated. In order to provide an overview of the situation and challenges associated with hybrid-electric propulsion, researchers at Bauhaus Luftfahrt have developed a “map” that illustrates the present state of knowledge on important hybrid-electric system concepts: The basic challenges and potentials for pure serial hybrids at component level are understood. In turbo-electric setups with thrust produced in parallel by electric and conventional drives, partial assessments are available. For integrated parallel hybrids, initial concepts were developed by Bauhaus Luftfahrt in the EU FP7 projects “E-BREAK” and “ENOVAL”. Most recently in “ENOVAL”, options for mechanically integrated parallel hybrid propulsion were evaluated in a conceptual sizing and performance study for a short-range aircraft application. Here, a most promising power plant layout, electrical systems configuration and feasible degree of power hybridisation were identified. Moreover, essential design and sizing strategies for mechanically integrated hybrid-electric aero propulsion systems were derived. The true efficiency potentials of hybrid-electric aero propulsion, however, are only accessible at the integrated aircraft level. Therefore, the impact of synergistically annexed airframe technologies still requires a much more detailed understanding.

  • Synopsis of important hybrid-electric propulsion options: Present state of knowledge on important hybrid-electric propulsion options: The true efficiency potential is only accessible at integrated aircraft level, which yet requires more detailed understanding.Synopsis of important hybrid-electric propulsion options: Present state of knowledge on important hybrid-electric propulsion options: The true efficiency potential is only accessible at integrated aircraft level, which yet requires more detailed understanding.
  • Integration options for hybrid-electric gas turbines: Basic power plant architectural options for a mechanically integrated parallel hybrid geared turbofanIntegration options for hybrid-electric gas turbines: Basic power plant architectural options for a mechanically integrated parallel hybrid geared turbofan